©2016byPaulD.Spudis

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Identifiers:LCCN2015033833|ISBN9781588345035|ISBN1588345033Subjects:LCSH:Moon–Exploration.|Outerspace-Exploration.|Spaceflight.|Spaceindustrialization.Classification:LCCQB582.5.S682016|DDC333.9/4-dc23LCrecordavailableathttp://lccn.loc.gov/

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CONTENTS

Cover

TitlePage

Copyright

Preface

1 Luna:Earth’sCompanioninSpace

2 TheMoonConquered—andAbandoned

3 AfterApollo:AReturntotheMoon?

4 AnotherRunattheMoon

5 ImplementingtheVision

6 Why?ThreeReasonstheMoonIsImportant

7 How?ThingsWeShouldHaveBeenDoing

8 IfNotNow,When?IfNotUs,Who?

9 AVisittotheFutureMoon

10 WhereDoWeGoFromHere?

Notes

ALunarLibrary

IllustrationCredits

Index

TPREFACE

wentyyearsago,IwroteTheOnceandFutureMoon(SmithsonianInstitutionPress, 1996).Thatbookdescribed the fieldof lunar science for the interested

nontechnical reader and explained what we had learned about the processes andhistory of the Moon from robotic and human missions. We were acquiring sometantalizing hints that the Moon was useful—that it contained the material andenergy resources necessary for a sustained human presence there. In the decadessincethen,explorationbyroboticspacecrafthasshownusmoreaboutthenatureoftheseresources,confirmingthattheMoonisamorecompellingdestinationthanwehadpreviouslythought.

Regrettably, strategic confusion currently abounds in the American civil spaceprogram. Despite the hype and disprovable propaganda that we are preparing toconducthumanmissionstoMars,suchaneffort isfarawaytechnically,politically,and especially fiscally.A program to extendhuman reach beyond lowEarth orbit(LEO)wasarbitrarily terminated in2010,andnorationalprogramwasofferedbytheadministrationasareplacement.Intothisleadershipvacuum,Congresssteppedforwardwith amakeshift program tobuild aheavy lift launchvehicle (theSpaceLaunchSystem)alongwithahumanspacecraftdesignedformissionsbeyondLEO.Nomission for these two itemshasbeenarticulated.Wewill soonhave somenicehardware,butnoplacetogo.

In part, this policy chaos resulted from a misguided attempt to re-create theApollo program. Apollo, now almost a half-century in the past, was the nationaleffort that sent humans to theMoon. Contrary to the belief ofmany, the Apolloprogramwasnotaboutspaceexploration—itwasaboutbeatingtheSovietUniontotheMoonbylandingamantherefirst.TheentireApolloprogramwasaColdWarbattle, and theUnitedStateswon.Afterward,we stoppedgoing to theMoon.ThewartimesettingofApollodictatedthatitbeconductedalongthelinesofawartimeprogram:withurgency,marshallingthebesttechnologyandindustrialcapacitywecouldmuster,andwithcostasasecondaryconsideration.

Since then, we have repeatedly failed to achieve sustainable space explorationbeyond LEO by trying to shoehorn it into the Apollo template. After landingAmericanastronautsontheMooninahighlyvisibleandsuccessfulmanner,perhapsitwasnatural to assume that this approach shouldbe the configuration for future

spaceendeavors.Butafter continually trying to re-create theApollo experiencebyfocusingonasimilarhumanmissiontoMars,withallpieceslaunchedentirelyfromtheEarth,weare littlecloser to thatgoal todaythanwewerefiftyyearsago.TheApollotemplate,appliedtotheevengreatertechnicalchallengeofaMarsmission,isenormouslydifficultandthus,enormouslyexpensive,requiringtenstohundredsofbillionsofdollarstoconductasinglemission.

AslowerbutaffordableapproachtotheproblemofahumanMarsmissionwouldbetograduallyandincrementally increasetherangeofspaceflight.Todothis,wewould need several technical developments, including reusable vehicles based inspace,stagingnodesatstrategicspacelocations,andtheabilitytoprovisionourselvesfor the trip from non-Earth resources, especiallywith high-mass, low-informationdensity items,suchas life-supportconsumablesandrocketpropellant.Toourgreatgoodfortune,naturehasprovideduswithareadilyavailablesourceforthismateriel—theMoon.

We can use theMoon to create new spaceflight capability.Water ice, themostusefulmaterialinspace,occursinabundanceatthepolesoftheMoon.Wecanaccessandextractthesevaluabledepositsbecausethepolesalsopossessareaswherewecangenerateelectricalpowernearlycontinuously.Thepolar“oases”ofthelunardesertallowus to live on theMoon and learnhow touse off-Earthmaterial and energyresources. This effort will create a new paradigm of spaceflight: to use what isavailable in space instead of launching it all from the deepest gravitywell in theinnersolarsystem,theEarth’ssurface.Suchadevelopmentwillrevolutionizespacetravel.

Of critical importance to achieving this revolution is working out how toaffordablyestablishapresenceon theMoon.Wehave limited timeandmoney tospendonspace. Ibelieve that there isapathto theMoon,onethataccommodatestheneedsoffederal,international,andcommercialinterests,avisionaryschemethatwillopenupthesolarsystemtoeconomicdevelopment.

Modern technical civilization depends on a variety of assets in space. Thesemachines monitor our weather and environment, provide instant globalcommunications,permitprecisionnavigationanywhereintheworld,andsecureournation and the world with strategic surveillance. Satellites are vulnerable, and anational presence in cislunar space—the space between Earth and the Moon—isessential to guarantee our continued and uninterrupted access to these assets. Arobust presence by the United States in cislunar space is necessary to assure thefutureemergenceoffreemarketsandtopromotethegrowthofapluralistic,politicalsystemonthenewfrontier.

ThisbooktellsthestoryofhowweoncewenttotheMoon,whatwefoundasaresult,ourvariouseffortstoreturnthere,andespeciallywhyandhowweshouldgoback.WegototheMoontocreatenewcapabilities.ItisthenextlogicalstepinspacebeyondLEO.

I thank my colleagues who critically read and reviewed all or parts of themanuscript: Sam Lawrence (Arizona State University), John Greuner (NASA–Johnson Space Center), Jack Frassanito (Frassanito and Associates, Inc.), TonyLavoie (NASA–Marshall Space Flight Center), and Ben Bussey (Johns HopkinsUniversityAppliedPhysicsLaboratory, currentlydetailed toNASAHeadquarters).Some figures were provided by Dennis Wingo (Skycorp, Inc.), Mark Robinson(Arizona State University), and Jack Frassanito. As always, my wonderful wife,Anne, is my most insightful critic, merciless editor, and best friend; I especiallythank her for editing multiple versions of this manuscript and for generalinspiration.

H

1Luna:Earth’sCompanioninSpace

umansdreamedoftouchingtheMoonformillennia.Itwasonlywithinlivingmemory thatwe actually left our planet and stepped upon the strange new

worldthatliesonourcelestialdoorstep.Recently,aninternationalflotillaofroboticprobes mapped the properties and determined the processes of this lunar world.Amazingly, it found that the Moon contains the material and energy resourcesneeded to establish a permanent, sustained human presence there.Water ice wasfoundnear thepolesof theMoon—billionsof tonsof ice, trapped in its cold,darkregions.Areasclosetotheseicedepositsarebathedinsunlightformostofthelunaryear.WaterandlightaretworesourcesthatpermitustousetheMoontocreatenewcapabilitiesforspaceflight.Thus,theMoonisanobjectofgreatutilitythatoffersusstrategicandoperationalpossibilitiesthatotherdestinationsinspacedonot.

Because the Moon is close, we can access it easily and continuously, unlikevirtuallyanyotherdeepspacedestination.TheMoon’snearnessmeansthatmuchoftheinitialworkofproducingwaterandpreparingthesurfaceforhabitationcanbedoneremotelywithrobotsunderthecontrolofhumanoperatorsonEarth.Uniqueamong space destinations, the proximity of the Moon allows us to begin itsdevelopmentbeforesendingpeople,makingthelunarsurfacethemostinexpensivespacegoalbeyondlowEarthorbit,wheresignificantprogresscanbeattainedearly.ThelowgravityoftheMoon(one-sixththatofEarth)enablesustouseitsresourcesto provision ourselves with the air, water, and propellant needed for theinterplanetaryjourneysthathumanitywillundertakeinthefuture.

TheMoonisasmall,complexsatellitewithaprotractedandfascinatinghistoryand evolution. The early history of the solar system, a distant age when planetscollided, globes melted, and crusts were formed and bombarded by impacts ofleftoverdebris,arerecordedintherocksandsoiloftheMoon.TheMoonhasacore,amantle,andacrust.Giantimpactcratersandbasinshaveexcavatedthousandsofcubickilometersofrockandthencrushed,melted,andreassembleditintocomplexforms.Internalmeltinggeneratedmagmas,whichwerereleasedontothesurfaceasmassiveoutpouringsof lava, flooding large regionsof the lunar surface.Followingthisperiodofviolentgeologicalevents,nearquiethaspresidedoverthelastbillionyears.ThefossilizedworldoftheMoonintriguesus,challengingourunderstanding

ofhowtheuniverseworks.Allof theseattributesplace theMoon in thehigh-valuecolumnwhen selecting

future strategic directions for humans in space.Wewent therehalf a century agolargelybecauseahumanlunarlandingwasadramaticspacegoalachievablewithina reasonable amount of time.Now, this sameproximity, coupledwith theMoon’sintrinsic interest and resources, again makes it an attractive destination. As weconsiderthis,itisimportanttoknowhowwewentbefore,whatwelearnedandwhytheMoon is the logicalnext strategicgoal for theAmerican spaceprogram. Iwillrelate thehistory of our efforts to return to theMoonand themultiple starts andstopsofthateffort.LikeSisyphusandhisstone,eachtimewethoughtwewereontheroadbackto theMoon,weseeminglyrolledbackto thebeginning.ButunlikeSisyphus,eachfailedattempttorestartlunarspaceflightresultedintheacquisitionofnewdataandinformationthathasshownusthattheMoonisanevenmoreusefuland invitingdestination thanwehadthought. It isawanderingandcomplex(butfascinating) story involving geopolitics, government spending, big science andtechnology,andnationalgreatness.

TheMoonasanObjectofWonder,Mystery,andWorshipAsthelargestobjectinournightsky,theMoonhasalwaysbeenanobjectofinterestand awe. From our first gaze overhead, we have wondered about and studied it,charting its path across the heavens. Because the Moon’s shape and appearancechangedwith regularity, it suggested to earlyhumans that therewas order in theotherwise capricious and potentially dangerous unknownworld around them.TheMoonallowedtheearliestlifeonEarthtomeasurethepassageoftime,predicttheseasons, and plan ahead—survival skills important to all species. Early religiousspeculation involved theworshipofnature.TheMoon’s changingappearanceoverthe course of a month, along with the passing of days and seasons, became thenaturaltimepiecewhoserhythmsandcycleshelpedhumansregulatetheirlives.Thecoincidenceofthedurationofthelunarcycletohumanmensessuggestedafemalepresenceintheheavens.Inthepantheonofdeities,MoongoddessesArtemis,Diana,andSeleneoversawthenaturalworld.

Evenafterancientnatureworshiphadbeenlargelyabandonedinwesternculture,theMoonremainedatimekeeperandanobjectofintrigue.BothJudaicandMuslimreligious calendars are lunar-based, not solar-based. Because the lunar and solarcycles arenot coincident,holidays suchasPassoverandRamadan fall ondifferentdateseveryyear.Asidefromitsearly,practicaluseasa timekeeper, theMoonalso

influenced culture. A full moon permitted considerable outdoor activity duringpreindustrialhistory,spawningtalesandlegendsofwerewolvesand“lunacy”—theidea that a fullmoon (Luna) could induce unnatural and abnormal behavior andactivity.1

Wenowknow thatEarth’sMoonhas been, andwill remain, intimately tied tohuman origins, history, and development. The Moon’s twenty-eight-day orbitaround Earth acts as a stabilizing influence on the obliquity of Earth’s spin axis,causing it to be stable for extended geological periods. Without this stabilization,rapid and chaotic changes in the orientation of its spin axis would make Earthoscillate wildly between climatic extremes, as happened on Mars. The Moon’srotation around Earth causes tides on its oceans and land, resulting in thedevelopment of periodically inundated coastal areas, sometimes below water andsometimes above it. Such terrain fluctuation is believed to have facilitated thedevelopmentof landcreatures,asmarinespeciesbeganto toleratebriefperiodsondryland.Thus,becauseofitsgravitationalinfluence,theMoonwasamajordrivingforceintheevolutionoflifeonEarth.

Anaxagoras(500–428BCE)wasamongthefirstoftheearlyGreeksphilosopherstoexaminetheMoonscientifically.HebelievedthattheMoondidnotshinefromitsown light, but merely reflected the light of the Sun. He also developed the firstcorrectexplanationofsolareclipses.Aristotle(384–322BCE)believedthattheMoonwasasphere,alwaysshowingthesamehemisphere(thenearside)tous.Aristarchusof Samos (310–230 BCE) calculated the distance between Earth and Moon at 60Earthradii,anastonishinglygoodestimate(initsellipticalorbit,theMoonactuallyvariesindistancebetween57to64Earthradii,orbetween363,000to406,000km).2

DuringtheMiddleAges,leadinguptotheRenaissance,orroughlythefifthtothesixteenthcenturies, theMoonwas simplyanotherobject toastronomers,but itdidplayakeyroleinthedevelopmentandevolutionofmodernphysicalscience.Galileo(1564–1642),anItalianphilosopher,physicist,andastronomer,notonlyobservedtheMoon with a primitive telescope but also conducted experiments on the laws ofmotion andwas an early convert to the Copernican system of a heliocentric solarsystem.TherecordedmotionsoftheMoonandplanetsagainstabackgroundoffixedstarsbycarefulobservers,suchastheDanishcourtastronomerTychoBrahe(1546–1601), led German scientist Johannes Kepler (1571–1630) to formulate his threelaws of planetary motion. A key insight is that planets and moons orbit theirprimaries in elliptical paths, not circular ones, as Copernicus (1437–1543) hadsuggested. As the Renaissance gave way to the Age of Enlightenment, EnglishphysicistIsaacNewton(1643–1727)synthesizedtheobservationsofTycho,andthe

lawsofplanetarymotionbyKepler,intoaunifiedtheoryofgravitation.Onceagain,theMoonplayedacriticalrole.AsNewtonobservedanapplefallfromatreeinhisgarden,hewonderediftheforceactingupontheapplewasthesameforcethatkepttheMooninitsorbitaroundEarth.Fromthissimplemusing,hedevelopedthelawsof motion and universal gravitation, a mathematical system that explained thephysicalworldinexquisite,clockworkdetail.

Although the naked eye cannot resolve individual landforms on the Moon,patchesoflightanddarkareasonitsvisibledischavebeendiscussedsinceantiquity,leadingtofancifulRorschach-likeinterpretations,rangingfromthefamous“ManintheMoon”torabbits,dogs,dragons,andawidevarietyofothercreaturesorobjects.ThedarkandlightareasarecausedbytheMoon’stwoprincipalterrains:thedark,smooth maria (Latin for “seas”) and the brighter, rougher terra (“land” orhighlands). The association of the dark terrain with seas has a muddled history.Galileo is often creditedwith it, buthedidn’t actually equate thedark areaswithwater; he only suggested that some “might” be so. Using the newly inventedtelescope, Galileo made drawings and wrote detailed descriptions of the complexlandformsthatmakeupthelunarsurface.3ByobservingtheMoonduringdifferentphasesandsurfaceilluminations,hesawthatitssurfacewasnotsmooth,assomeoftheclassicalphilosophershadsurmised,butroughandjagged,consistingoftoweringmountains and most significantly, circular depressions in a wide variety of sizes.EventhoughtheMoon’snearsidehadbeenthoroughlymappedandremappedbyastronomersovertheprevioustwohundredyears,theuseoftheword“crater”(fromtheGreekwordmeaningcuporbowl)todescribetheseholeswasnotuseduntilthelateeighteenthcentury.

With the advent of increasinglymore powerful telescopes, the landscape of thelunarnearsidebecameknowninmuchgreaterdetail(figure1.1).Astronomersnowmoved past theMoon to themore interesting stars, nebulas, and galaxies beyond.Lunar studieswere left to a few diehards,mostly amateur astronomers and roguegeologists.ThevastbulkofworkontheMooninthenineteenthandearlytwentiethcenturiesdealtwithdescriptionsandstudiesofitssurfacefeaturesandhistory—mostpressingly, the problem of the origin of craters. There were two opposing campsregarding craters. One group held that volcanic explosions and eruptions formedcraters,whiletheothergroupbelievedthatcratersweremadebytheimpactofsmallbodies, suchasasteroidsandcomets.4Thisdebategrew tonear religious intensity,often with more heat than light being shed on the problem. The two proposedmechanismshadverydifferentimplications.ThevolcanichypothesissuggestedthattheMoonwasanactivebody,withinternalheatandongoingvolcanism.Theimpact

ideasuggestedinsteadthattheMoonwascoldanddeadandmightneverhavehadany internal activity. To support their arguments, each side marshaled the bestexamplestheycould;fewanaloguesfromthestudyofEarth’slandformswereofanyhelp.AlthoughEarthhasmanyvolcanoes thathavebeen studied for years, at thebeginningofthetwentiethcentury,norecognizedterrestrial impactfeaturehadasyetbeendescribed.

Figure 1.1. View of the waxing gibbous Moon generated from LRO WAC images. The dark, smooth plains

(maria) are basaltic lava flows, mostly erupted before three billion years ago. The rough, heavily cratered

highlands(terrae)aretheremnantsoftheoriginallunarcrust.Brightspotsarefreshcraters.(Credit1.1)

In 1892, Chief Geologist of the US Geological Survey Grove Karl Gilbert,intriguedbythecratersoftheMoon,spentmanynightsstudyingthelunarsurfacethroughatelescopeatWashington’sNavalObservatory.Gilberthadheardalectureaboutmeteorite fragments that had been collected near a feature known as CoonButteinnorthernArizona.MineralogistAlbertFootedescribedtheseironmeteorites

andnotedtheirproximitytoCoonButte,butdidnotgosofarastoconnectthetwoin origin. Gilbert decided to study Coon Butte as a possible impact crater. Bycarefully measuring the shape of the crater, he calculated the likely size of animpacting ironmeteorite.Hepostulated that the remnants of suchanobjectmustcurrently exist beneath the floor of the crater and used a magnetic dip needle(designed to show variations in Earth’s magnetic field) to search for what hebelieved should be an enormous buried iron body below the surface. But afterintensive mapping failed to reveal the buried meteorite, Gilbert reluctantly (andwrongly) concluded that the Coon Butte crater must be a volcanic steam vent.5Today, Coon Butte is known as Meteor Crater and is considered the world’s firstdocumented meteorite impact site. How did Gilbert get its origin so wrong,especiallysincehehadspecificallytestedtheimpactidea?

Gilbert did not understand that an impact at extremelyhigh velocities (greaterthan10km/second)producessuchenormousenergiesthattheprojectileessentiallyvaporizesasapoint-sourcereleaseofenergy;leftbehindisabigholewithnoburiedironbodybeneaththecraterfloor.Animpacteventisverysimilartothedetonationof a nuclear bomb. In fact, the formation of Meteor Crater fifty thousand yearsearlierbytheimpactofanironmeteoritemusthavelookedverymuchlikeanuclearexplosion, complete with blinding flash and subsequent mushroom cloud.Documentation that this crater formed by impact opened the floodgates to therecognition and cataloging of dozens of impact craters on Earth (a process thatcontinues to this day). Study of these features taught scientists to recognize thephysicalandchemicaleffectsofhighvelocityimpact,knowledgethatwouldbecomecritical in future interpretationsof samples fromtheMoonandfora startlingnewinterpretationofEarth’shistoryaswell.

TheMoonasDestination:TheSpaceRaceThe idea that we might someday travel to the Moon was often the subject ofimaginative fiction, but such a journey could not be seriously contemplated untilKonstantinTsiolkovsky,HermannOberth,andRobertGoddardhaddeveloped thebasicprinciplesof rocketryandspaceflight.6The technologyof rocketsmadegreatstrides under the impetus of war, as Germany developed the world’s firstintercontinentalballisticmissile(ICBM), theA4(or“V-2”asHitlerdubbedit). IntheyearsfollowingWorldWarII,intensiveworktowardthedevelopmentoflargerandbetter ICBMs asweapons ofwar led to the advent ofEarth-orbiting satellites(SovietSputnikin1957andAmericanExplorer1in1958)andusheredintheSpace

Age. War and space were tightly coupled from the beginning, since the first useenvisionedforspacerevolvedarounditspossiblevalueasabattleground.

Given thisbackground, itwas inevitable that theMoonwould emerge as akeyobjectintheexplorationofspace.Indeed,tripstotheMoonbeganshortlyafterthebeginningof theSpaceAgewith the flightofLuna2 in1959.ThisSoviet roboticprobehittheMoonafterathree-dayjourney,makingitthefirstman-madeobjecttoreach another extraterrestrial body. Because of theMoon’s prominence in the skyand its proximity toEarth, it quicklybecame the focus of the first race into spacebetween the United States and the Soviet Union. In May 1961, responding to agrowing sense of geopolitical competition, President John F. Kennedy declared anational goal of a human lunar landing by the end of the decade. It was widelyassumedthattheUSSRhadacceptedAmerica’schallengeandthatthe“RacetotheMoon”wason.Aseriesofactivities inEarthorbitconductedbybothnations soonfollowed, filling that decade with new space accomplishments, which includedextravehicular activities (spacewalks), the rendezvous and docking of two orbitalspacecraft, long-duration flights (up to two weeks), flights to extremely highaltitudesinthehundredsofkilometers,andthemasteryofcomplexorbitalchanges.AllofthesetechniqueswouldbeneededforahumanmissiontotheMoon.

Meanwhile, theUnitedStates launcheda seriesof robotic spacecraft toexamineandscouttheMoon.Thesemissionsprobeditssurface,landedsoftlyonit,examinedthesoil,tookhigh-resolutionimagesofitssurfacefeatures,andpreparedthewayforfuturehumanmissions.TheRanger(impactors),Surveyor(softlanders),andLunarOrbiterseriesgaveusafirst-orderunderstandingoflunarsurfacefeatures,processesandhistory.7Scientistsandengineerslearnedthatthesurfacewasdusty,yetstrongenough to support the weight of a lander and astronauts. Craters covered everysquaremillimeterofitssurface,ranginginsizefrommicroscopictoenormousbasinsspanningthousandsofkilometers.ThelandscapeofthefarsideoftheMoonturnedouttobeverydifferentfromitsnearside,withanear-absenceofthedark,smoothmariathatcovermuchoftheEarth-facinghemisphere.Manyunusuallandformsofnon-impactoriginwerefoundinthemaria,stronglysuggestingitsoriginasvolcaniclava flows. Assuming thatmost craters were formed by impact, their density anddistributionsuggestedthattheMoonwasanancientworld.Itssurfacetoldastoryofhavingbeingexposedtospaceformanymillionstobillionsofyears.

TheresultsoftheApollomissions,alongwith380kg(842pounds)ofrockandsoilsamples returned to Earth, largely confirmed and extended these inferences.8WefoundthattheMoonismadeupofsomeofthesamerock-formingmineralswidelyfoundonEarthandthatitformedalmost4.6billionyearsago,aboutthesametime

asEarth.The samples suggested that the earlyMoonhad beennearly completelymolten, covered by an “ocean” of liquid rock. After this magma solidified at 4.3billionyears,abarrageofasteroidsandcometsbombardedtheMoon’ssurfaceforthenext400millionyears,mixing-up thecrustandcreatinga rough,heavilycrateredsurface.Afinalcataclysmicseriesoflargeimpactsabout3.9billionyearsagoformedtheyoungestbasins,includingthelarge,prominentImbriumbasinonthenearside.The low areas of impact basins slowly filledwith volcanic lava over the next 800millionyears.Formostofthelastcoupleofbillionyears,theMoonhasbeenlargelyinactive,withonlytheoccasionallarge-bodyimpactpunctuatingtheslowandsteady“rain”ofmicrometeoritesthatcontinuetogrindsthesurfaceintoafinepowder.

This brief sketch of the history and evolution of the Moon describes a morecomplexplanetarybodythanhadbeenimaginedbeforetheSpaceAge.TheMoon’sscarred,ancientsurfacerecordsnotonlyitsownhistory,butalsothatofimpactsinthe Earth-Moon system as well. Because the Moon has no atmosphere or globalmagneticfield,thedustgrainsofthelunarsurfacealsorecordtheparticleoutputoftheSunforthelastthreebillionyears.WiththeMoonasa“witnessplate”toeventsinthispartoftheuniverse,thisgeologictimecapsuleremainsvirtuallyuntouched,waitingtoberecoveredandread.AlthoughwefoundthattheMoonisdepletedinvolatileelementscomparedtoEarth,wehaveonlyexploredthelunarsurfacewithpeopleatsixsites,allrelativelyclosetotheequatorandonthenearside.Onecannothelpbutwonderwhatpossiblesurprisesawaitusattheregionsnearthepolesoronthefarside.

Mostpeoplearefamiliarwiththepoliticalandpop-cultureeffectstheSpaceRacehadontheworld,buttheyarenotaswellversedontheprofoundscientificimpactoftheApollomissions.Forthefirsttime,wehadcollectedsamplesfromanotherworld,takenfromsitesofknownlocationandgeologicalcontext.Wetookwhatwelearnedfrom these physical samples and coupled it with the global data gained from theroboticprecursors.Addedtothisknowledgewasinformationattainedfromregionalareasthroughremotesensing.CombiningallofthesedataallowedustoreconstructthestoryoftheMoonwithahighdegreeoffidelity.Themostimportantdiscoveryof the Apollo studies was recognition of the critical importance of the process ofimpact on the history and evolution of the solar system. From an elusive andquestionable idea in the pre–Space Age era, the collision of solid objects becamerecognized as the dominant, fundamental process in planetary formation andevolution.Becausewehadlearnedtorecognizethephysicalandchemicaleffectsofhypervelocity impact through the study of the lunar samples, we soon recognizedthatlargebodyimpactshadoccurredonEarthinthedistantpast.Inparticular,the

extinction of the dinosaurs 65million years agowas recognized tohavehappenedsimultaneously with the impact of an asteroid 10 kilometers in diameter. Thisobservation, suggestingthat impactsmightcausemassextinctionsof life,was soonextendedtootherextinctioneventsevidentinEarth’sfossilrecord.9Somescientistsnow think that mass extinctions caused by impact may be one of the principaldriversofbiologicalevolution.Thus,becausewewenttotheMoonmorethanfortyyearsago,wenowunderstandsomethingveryprofoundaboutthehistoryoflifeonourhomeplanet—anunderstandingthatholdscluesaboutourpastandposessomesoberingimplicationsforourfuture.

TheMoonasanEnablingAssetFor all of its impressive scientific and technical accomplishments, the Apolloprogram left many space advocates wanting. Because it was primarily driven bygeopolitical conflict and designed to demonstrate our technical superiority, onceApollohadachieveditsobjectiveof“landingamanontheMoonandreturninghimsafelytoEarth,”asPresidentKennedy’sproclamationputit,therewasnolongeranyreason to continue returning to the Moon or to go beyond into the solar system.Thus, the program held within itself the seeds of its own demise. The rates ofexpenditure acceptable during the Apollo program were simply not politicallyfeasible for any follow-on space program.10 So the decisionwasmade tomake anattempttolowerthecostofspaceflightviaareusablespaceshuttle.Whilethiseffortdid not succeed in lowering costs, the development of the shuttle led to somesignificantanduniquecapabilities.Moreimportantly,itpointedthewaytowardanalternative architectural template for spaceflight, one in which small pieces,incrementallylaunchedandthenassembledinspaceandoperatedasalargesystemof systems,mightmultiply spaceflight capabilities carried out over a longer,moresustainable period of time. This template of operations reached its acmewith thecompletionoftheInternationalSpaceStation(ISS).

AsformissionstotheMoon,therewasonlysilenceandisolation.Severalattemptstoflyanunmannedorbitalmissiontoobtainadditionalglobalremotesensingdata(which would permit better interpretation of the superb Apollo sample database)were unsuccessful. With the focus of the human program centered on the spaceshuttle and the subsequent building of a space station in low Earth orbit, littleinterest in additional lunar exploration was evident. Then, in the mid-1980s, aconfluenceofeventsoccurredtofocusattentiononceagainontheMoon,aninterestthatcontinuestothepresent.Firstcametherealizationthatafterthebuildingofthe

space station, an orbital transfer vehicle designed to reach high orbits, such asgeosynchronous (~36,000 km or 22,000miles high),was the obvious next step. AvehiclethatcanreachgeosynchronousEarthorbit(GEO)canalsoreachtheMoon.Thus,aseriesofstudiesfocusedonthepossibilityoflunarreturn,withanemphasisonlonger,morepermanentstaysonthesurface.

Figure1.2.OrbitalgeometryoftheEarthandMoon.TheEarth-MoonsystemorbitstheSunwithintheplaneof

theecliptic.TheMoon’sorbitalplaneis inclined5.1°fromtheecliptic,andtheMoon’sspinaxis is tilted6.7°.

ThisresultsinanearlyperpendicularorientationoftheMoon’sspinaxistotheecliptic(calledobliquity)of1.6°.

ThisisincontrasttheEarth’sobliquityof23.4°.

TheideathatwemightwanttoremainontheMoonfor longerperiodsoftimeinevitablyledtotheconceptofobtainingsomesupplies locally,fromthematerialsandenergy foundandavailableon theMoon.This concept, called in situ resourceutilization (ISRU), is an essential skill for humans to master if we are to besignificantly and permanently present in space and on other worlds.11 Thatrealization led to a renewed interest in getting additional lunar data—mostespecially,datafortheuniquelocalenvironmentfoundattheMoon’spolarregions.Because the spin axis of the Moon is nearly perpendicular to the ecliptic plane(figure 1.2), the Sun is always on the horizon at the poles. Some areas are inpermanentdarknessandhence,verycold.Itwasrecognizedthatthese“coldtraps”might contain deposits of ice, along with other volatile substances deposited overgeological time as water-bearing comets and asteroids collided with the Moon’ssurface. Additionally, other areas near the poles might be bathed in permanentsunlight.Thisnear-continuousenergysourceallowsforthegenerationofelectricalpower during the long, two-week lunar night. At the time, we did not know thedetails of these hypothesized properties or even if they actually existed.However,overthepast twentyyears,anumberof lunarroboticmissionshaverevolutionizedourknowledgeoftheMoon,andinparticulartheenvironmentanddepositsofthepoles.

In1994,theDepartmentofDefenseClementinemissionmappedthemineralogyand topography of the entireMoon fromorbit.An improvised experiment on thisflight used the spacecraft transmitter as a radio source to illuminate dark areas

withincratersnearthepoles.Analysisofradioechoesfromthesouthpolesuggestedthepresenceofwater ice in thecraterShackleton.ThisdiscoverywasconfirmedafewyearslaterbytheLunarProspectorspacecraft,whichfoundenhancedamountsofhydrogenatbothpoles.Thesediscoveriesstunnedthelunarsciencecommunity,since earlier results from the study of the Apollo samples had suggested that theMoon was bone-dry and always had been. Now, that concept—and ourunderstanding of theMoon and its history—had to be reevaluated.Over the nextfew years, additional results from sample studies, remote sensing, and theoreticalmodelingculminatedintheunequivocaldetectionofwatervaporandiceduringtheimpact of the LCROSS spacecraft, thus demonstrating beyond any doubt thatsignificant deposits of water ice are present at both lunar poles. Conservativeestimatesoftheamountofwatericerunbetweenseveralhundredmilliontomorethanabillion tonsateachpole.Additionally,wehave foundthat smallareasnearbothpolesareilluminatedbytheSunforextendedperiodsoftime,someformorethan nine-tenths of the year. All of this new lunar data has countries around theworldplanningways toaccess theenergyandresourcebonanzaat thepolesof theMoon,availabletothosewhoarrivefirst.

Materials and energy are available on the Moon, two critical requirements forextendedhumanpresence.Water,initsdecomposedformofhydrogenandoxygen,not only supports human life but is also the most powerful chemical rocketpropellantknown.Near-permanentsolarenergyisavailableproximatetothewater-rich cold traps at the poles. The previously misleading image of the Moon as abarren,uselesswilderness (aspaintedbyApollo results)hasgivenway toa richer,more inviting, useful persona.Theworldnowknows that theMoon is not simplyanother destination in space—but that it is an important enabling asset forspaceflight. Our current understanding of theMoon is vastly different from thoseearly humanswho first gazed up, grateful that they had theMoon tomark theircalendarsandcharttheseasons.WenowunderstandthattheMoonisaworldinitsownright,anobject located inourcosmicbackyardwhoseresourceswecanaccessandusetotravelthroughoutthesolarsystem.

OurFutureonLunaSpaceengineerandvisionaryKrafttEhrickeoncesaid,“IfGodhadintendedmantobe a space faring species, He would have given him a Moon.”12 This tongue-in-cheekstatementisevenmoreapplicabletodaythanwhenEhrickefirstsaiditmorethanthirtyyearsago.

WhyistheMoonadestinationforhumanity?Becauseitcanbeusedtoopenupthefrontierofspacethroughthedevelopmentofitsmaterialandenergyresources.ByharvestingthewatericeandsolarpoweravailableatthepolesoftheMoon,wecreate the ability for long-term human presence on the Moon and in near-Earthspace.Water can fuel a permanent, reusable space transportation system that canaccessnotonlythelunarsurfacebutalsoeveryotherpointbetweenEarthandMoon.Thiszone,calledcislunarspace,iswhere95percentofoursatelliteassetsreside.Theability toreachtheseplaceswithpeopleandmachineswillallowus tobuildspacesystemsofextraordinarypowerandcapability.Moreover,suchasystemcanalsotakeustotheplanetsbeyondEarthanditsMoon.13

WecanusetheMoontolearnhowtoliveandworkeffectivelyandproductivelyonanotherworld.Thisgoalrequiresustolearnhowtobuildprotectiveshelters,safefromthethermalandradiationextremesofdeepspace.Toprovisionourselves,wemust learnhow to extract our supplies from local resources, including life supportconsumables, and learn how to build infrastructure using local resources forconstructionmaterials.Onceestablishedonthelunarsurface,wewillusethesenewcapabilities to explore our nearest neighbor in space as well as to build a“transcontinental railroad” in cislunar space and establish apermanentbeachheadoffEarth.OntheMoon,wewill learnhowtoexploreaplanetusingtheoptimumcombinationofpeopleandrobots,eachdoingthetasksatwhichtheyuniquelyexcel.Finally, we will reveal and decipher the record of planetary and solar systemevolution recorded in the rocks of the Moon. Some mysteries uncovered by theApolloexplorationsrevolutionizedEarthscience.Additionalexplorationwillrevealevenmore startling secrets and continue to revolutionizeourunderstandingof theworldanduniversearoundus.

WhyisitimportantfortheUnitedStatestomaketheMoonahighprioritygoal?Because the United States is not the only nation interested in it. This coin ofinternational interest has two sides. On the positive side, our partners in currentspace endeavors, such as the International Space Station, have expressed greatinterestinhumanmissionstotheMoon.Somehavebeguntheprocessofgatheringdetailed information from precursor robotic missions to enable future humanmissionstotheMoon.Howcanweproclaimworldleadershipinspaceifweignoreaprominentdestination that somanyothernations are anxious tovisit andexploit?Nations such as China have plans to explore and use theMoonwith both roboticmachines andwith people.While their lunar intentions appear benign at present,theyaredevelopingcapabilitiesnowthatcouldposeathreattothesecurityofthisnationandothercountriesinthenearfuture.Thus,thereisastrategicdimensionto

American lunar presence. It is vital to the security and economic health of thecommunityofnationsthatfuturesocietiesinspacedevelopaccordingtopluralistic,democratic principles and that commerce is open to freemarkets,with respect forpropertyrightsandcontractlaw.AlthoughAmericanpresenceincislunarspacedoesnotguaranteesuchanoutcome,ourabsencefromthistheatercouldwellresultinthereverse.

Whatmakes theMoon both important and unique? It is close, interesting, anduseful. The close proximity of theMoon to Earthmeans thatwe can always andeasily access it, unlike the limited and infrequent launch windows to all otherplanetarytargets.Thisnearnessmeans thatmuchof theearlypreparatoryworkattheMooncanbedonebyrobotsonthelunarsurface,asdirectedfromEarth.Thus,thefirsthumanstoreturntotheMooncanarriveatafullyfunctional,turnkeylunaroutpost, assembled in advance by these teleoperated robots. Interest in the Moonderives from its role as a small planet of complex and interesting process andevolution. The Moon’s environment permits unique and specialized scientific andengineeringexperimentstobeconducted—studiesnotpossibleanywhereelseinthesolar system. We will find the answers to questions surrounding our moon’scomplexity and gain a fuller understanding of our home planet’s early evolution.TheutilityoftheMoonliesinitsmaterialandenergyresources,theaccesstowhichwill allow us to acquire the knowhow and means for humanity to plant its firstfootholdonanotherworld.

H

2TheMoonConquered—andAbandoned

ow is it that America went to the Moon, going from nearly zero spacecapabilityto the lunarsurface in less thanadecade,andthenrapidly left it?

Why have we not been back since? Within that tale are important lessons, someneverfullyabsorbedbyeitherhistoriansorournationalleadership.Millenniabeforeweachievedit,humansdreamedaboutgoingtotheMoon.Theactualcircumstancesof our journey had not been imagined by science fiction authors and as a result,virtually all science fiction dealing with lunar travel made the first landing thebeginning(nottheend)ofhumanity’smovementintospace.Now,itremainstobeseenwhetherourfirststepsontheMoonreallywasanending,ormerelythepreludetoadelayedgoldenageofspaceflight.

JourneystotheMooninFictionandFactThe idea that some day we would be able to journey to the Moon is very old,conceivablygoingbackasfarastheearlycavedwellers.Thefirstliterarydescriptionof trips to theMoon, Sun, and otherheavenly destinationswas likely thework ofLucian of Samosota (125–180CE). JohannesKepler, the discoverer of the laws ofplanetarymotion,wroteSomnium(“Dream,”publishedposthumouslybyhissonin1634).Inhisnovel,KeplerdescribesatriptotheMoonandtheviewofEarthandthe solar system from its surface. English clergyman John Wilkins wrote severalbooksabouttripstotheMoon,themostfamousbeingTheDiscoveryofaWorldintheMoone(1638).Init,heoutlinedtheideathatsomedaypeoplemightinhabittheMoon.IncludedinWilkins’sworkwereexoticandinfeasibletechniquesonhowtogetthere,suchastransportbyangelsorwiththehelpofharnessedfowl.

DuringtheIndustrialAge,authorsofclassicsciencefictiontookmorereasonable(ifstillfanciful)approachestotheproblemoflunarflight.InJulesVerne’sFromtheEarthtotheMoon(1865),voyagerswereshotfromahugecannon(theColumbiad)inordertoreachescapevelocityandlandontheMoon.Verneskippedoverhowtheaccelerationfromacannonshotwouldcreateenormousg-forcesthatwouldkillhiscrew;healsomisunderstood thenatureofweightlessnessbyhavinghispassengers

experienceitonlywhenhismoonshipcrossedthegravitationalspheresofinfluencebetweenEarthandMoon.KonstantinTsiolkovsky,theinventorofastronauticsandthefirst toderivetherocketequation,was inspiredbyJulesVerneandpennedhisownnovel,On theMoon (1893).Thecharacter inTsiolkovsky’s storywakesupontheMoonandexperiencestheunusualeffectsofbeingonanalienworld.Curiously,considering his contributions to rocket science, Tsiolkovsky does not record thedetailsofthetripfromEarth.TheapproachofH.G.Wellswasevenmorefantastic:A special substance calledCavorite (named for its inventor, a character inWells’s1901novelFirstMenintheMoon)cutsofftheforceofgravity,allowinghissphereto effortlessly travel to the Moon. Once there, the voyagers find large insectlikecreaturesthatlivebelowthelunarsurface.

TheMoonwasliftedoutoftherealmoffictionandfantasyandputbackintothedomainofsciencewiththeadventofmodernrocketry(anoutgrowthoftheSecondWorldWar).Startingwithafeweccentrics,theMoononceagainbecameatopicforscientific inquiry. Ralph Baldwin, an astronomy student at the University ofChicago,afternoticingthespectacularseriesoftelescopicphotographsondisplayinthe lobby of the Adler Planetarium, began cogitating about the origin of craters,basins,andtheevolutionofthelunarsurface.Hewrotedownthoughtsforacoupleof articles before being pressed into war service, where he helped develop theproximity fuse. After the war, Baldwin collected his lunar ideas into a book,TheFaceof theMoon (1949).1Thispre–SpaceAge synthesiswasa fairlycompleteandaccurate account of theMoon’s processes and history—how the craters and basinswere formed by impact, that the dark smooth maria were volcanic lava flows(Baldwincorrectlyidentifiedthemasbasalt),andthattheMoon’ssurfacewasveryoldcomparedtothatofEarth’s.Baldwin’sstudyoftheMooncontinuedthroughouthis life, and he lived to see virtually all of his surmises validated through theexplorationoftheMoonbytheApollomissions.

Shortlyafterthisworkappeared,thenotedsciencefictionauthorArthurC.ClarkepublishedTheExplorationofSpacein1951.2Clarkeoutlinedanexpansivevisionofthefuture,includingrocketsintoEarthorbit,tripstotheMoon,andvoyagestotheplanets. Interestingly, hemade some careful and prescient observations about theissuesoflandingandsustainingapermanenthumanpresenceontheMoon.Clarkeconsidered the Moon an essential way station on the road to the planets. Herehumanswouldlearnthetechniquesofexploringandlivingonanalienworld.Clarkespecifically recognized that using the mineral resources of the Moon to supporthumanpresence and createnew capabilitieswas essential.Hepointed out that, atleast intheearlyphasesofoperation,centralizingoperationsatasinglesiteonthe

Moon would permit concentration of resources to maximize capabilities quickly.Thus, Clarke advocated building a base, not multiple sortie missions to manydifferentlocations.Aftertheestablishmentofapresenceatabase,wewouldbeabletoexploretheentireMoonatourleisure.

AccountsholdthatNobelPrize–winningchemistHaroldUreybecameengrossedby The Face of the Moon when, by chance, he picked up the book at a party.Baldwin’s description of the lunar landscape and the impact origin of its cratersconvincedUrey that the primitive, ancientMoonheld secrets to the origin of thesolar system. He went on to lead an effort that applied the basic principles ofchemistryandphysicstotheoriginandevolutionoftheMoonandplanets.3Anotherastronomer,GerardKuiper,heldthe“heretical”viewthattheMoonandtheplanetswere worthy objects for observation and scientific study. For further study andmapping, he collected the best telescopic images of the Moon at the Lunar andPlanetary Laboratory that he established in 1960 at the University of Arizona inTucson. Geologist Eugene Shoemaker, who was mapping uranium deposits innorthernArizonafor theUSGeologicalSurvey inthe1950s,decidedtoreexaminethegeologyofCoonButte, the featuredismissedbyG.K.Gilbert asnotbeing animpact structure sixtyyears earlier.Using thegeologyof the crater tounravel themechanicsofhypervelocityimpact,includingthediscoveryofformsofsilicacreatedonly under extremely high pressures, Shoemaker decided that Coon Buttewas animpactcrater.IthasbeenknownasMeteorCratereversince.4

ButGeneShoemakerdidmore than justdocument the impactoriginofMeteorCrater.In1960,hemadethefirstgeologicalmapofthelunarsurface,showingthebasic sequence of events that had occurred there. In brief, this technique involvesusingoverlapandsuperpositionrelations toclassify laterallycontinuousrockunits,includingsheetsofcraterejectaandlavaflows.Thesepropertiescanbedetermineddirectly from visual observations and photographs. Shoemakermapped the regionnear the crater Copernicus on the near side, working out the basic framework oflunar stratigraphy—that is, the sequence of layered rocks.5 He then used thisinformationtoestimatethetimecorrelationbetweeneventsontheMoonandthoseon Earth, concluding that the Moon preserved an ancient surficial record, whichholdspartoftheearlygeologicalstorymissingfromtheerodedanddynamicsurfaceofEarth.

Thesescientistsandtheirresearch,eachintheirownway,madethestudyoftheMoonanditsprocessesscientificallyrespectable.AfterthelaunchofthefirstEarth-orbiting satellite Sputnik 1 in October 1957, it was reasonable to imagine thatspacecraft might be sent to the Moon. Soon, observations of the Moon’s surface

through telescopes, the mapping of terrestrial impact craters, and compositionalstudies of rocks from terrestrial impact craters and meteorites (rocks from space)became part of cutting-edge lunar science. A gradual but perceptible momentumbegan to formulate a conceptualmodel that would allow us to explore theMooneffectively and give us an understanding of its history. Some dreamed that theymight live to see people travel to the Moon in their lifetimes (and Shoemakerplanned on being one of them). Shoemaker’s dreamwould come true in part, butundercircumstancesthatnooneforesaw.

TheApolloProgramInaseriesofarticlespublishedinCollier’sinthe1950s,rocketscientistWernhervonBraunoutlinedaplantosendpeopletotheMoonandtoMars.6Accompaniedwithcolorful illustrationsbyspaceartists suchasChesleyBonestell,vonBraun’sarticlescaught the imagination of the public, including a very imaginative Walt Disney,whowentontofeaturevonBraun’sideasinaseriesofprogramsaspartofhisnewtelevision seriesDisneyland (1954). Viewerswere treated to a four-program seriesoutliningthebasicvonBraunarchitecture:rockettoEarthorbit,spacestation,Moontug,andhumanMarsspacecraft.Thissteppingstoneapproachmadebothlogicalandprogrammatic sense. Each piece enabled and supported the next step into space.Although some technical details in vonBraun’s planwere out of date before theywererealized—forexample,vonBraunhadelectricalpower in spacegeneratedbysolar thermal power alternately vaporizing and condensing mercury to driveturbines, a technologymade obsoletewith the advent of solar photovoltaic cells—major parts of his scheme enabled the establishment of a robust and permanentspacefaringsystem.

However, internationaleventssoonintervenedonvonBraun’sorderlyapproach.The advent of the Apollo program altered what was to have been a logical,incremental,andthoughtfulspaceplanintoaraceoncecompetitionwiththeSovietUnionbecameouroverridingconcern.TheslowapproachhadtobeacceleratedoncePresident Kennedy committed the nation to a decadal deadline. Under ordinarytechnical development, each piece would be designed, built, flown, and modifiedaccording to its performance. But with scheduling pressure designed to beat theSoviets to theMoon,amuch fasterapproachwas required.This causedvonBraunand others at the newly created National Aeronautics and Space Administration(NASA) to reexamine the problem of sending people to theMoon.Didwe reallyneedaspacestationfirst?Orwasitpossibletobuildalaunchvehiclebigenoughto

sendanentireexpeditiontotheMooninonefellswoop?Althoughthespaceagencyhadalreadybegunplanningforthedevelopmentofa

new super heavy lift rocket and had done some preliminary studies of mannedmissionstotheMoon,theannouncementofalunarlandinggoalbyPresidentJohnF. Kennedy inMay 1961 shockedmany at NASA. It was one thing to daydreamaboutsendingpeopleintodeepspaceandtotheMoon,butquiteanothertoactuallybegiventhetasktodoso—andthenbringthembacksafelytoEarth,astipulationofKennedy’s declaration. When the commitment to go to the Moon was made, thetotalmannedspaceflightexperienceoftheUnitedStatesconsistedofAlanShepard’sfifteen-minute-longsuborbitalhop.Alunarvoyagewouldrequirethemasteryofavarietyofcomplexspacefaringskills,includingprecisionnavigationandmaneuversnecessarytochangeorbitinflight.

Thedesignor“architecture”foramannedlunarmissionwasdebatedextensivelybeforethe“modedecision.”Initialplanscalledforeitheradirectascenttothelunarsurfaceorarendezvousof twolaunchedspacecraft inEarthorbit.Bothapproachescalled for the development of a “super” heavy lift launch vehicle, Nova, a rocketcapable of launching up to 180metric tons to lowEarth orbit.7 JohnHoubolt, anengineeratLangley,advocatedinsteadforsomethingcalledlunarorbitrendezvous.8Thiscalledforasmallvehiclethatwouldlandonthelunarsurface,thenreturntorendezvouswiththeApollospacecraftthathadremainedinorbitaroundtheMoon.Althoughthismissionprofilewasthoughttobeveryrisky(arendezvoushadneverbeenaccomplishedinspace,letaloneoneinvolvingtwoseparatespacecraftorbitingtheMoon), itdidenable thevoyage tobe launched“allup”ona singleheavy liftrocket.ThisdesignbecametheSaturnV,arocketcapableof launching127metrictonstolowEarthorbit.

With the principal design features of Apollo outlined, the American spaceprogramnextundertookaseriesofmannedandunmannedmissionsinpreparationforalunarlanding.Whilehumanmissionspracticedspecifictechniques(includingrendezvous and docking), roboticmissions gathered information about theMoon’ssurface conditions and environment and sought to identify a smooth, safe landingsite.InpreparationfortheMoon,weflewsixsingle-manMercurymissions,tentwo-man Gemini missions, and four three-man Apollo rehearsal flights. There werethirteen successful roboticprecursormissions to theMoon: threehard-landers, fivesoft-landers, and five orbiters. All this occurred within the eight years betweenKennedy’s speech and the landing of Apollo 11, a span of time that included theassassinationofPresidentKennedyonNovember22,1963,andatwenty-two-monthstand-down after the tragic fire on Apollo 1 of January 27, 1967, which killed

astronautsVirgil“Gus”Grissom,EdWhite,andRogerChaffee.TheApollospacecraftwasextensivelyredesignedandmodifiedaftertheApollo1

fire. Following a highly successful checkout of the newly refurbished Command-ServiceModulesinEarthorbitonApollo7,aneleven-daymissioninOctober1968,theplannedjourneyofApollo8toorbittheMoonseemedtobeabold,evenrecklessmove.Afterall,aspacecraftsenttotheMoonwithoutanyrescuecapabilityusingalunarmodule (LM)couldhaveended in tragedy,aswasdemonstrateda fewyearslaterduringtheApollo13mission.Wenowknowthattherewasareason,onethatwaswithheldfromthepublicatthetime,forsendingApollo8onalunarjourney.TheCIAhadintelligencethattheSovietswereplanningamannedflightaroundtheMoonbytheendof1968.TheyhadjustcompletedacircumlunarmissionwiththeirunmannedZond8,whichdemonstratedthatthepiecesforsuchaflightwereready.Itwasbelieved,probablycorrectly,thatiftheSovietswereabletopullthisoff,theywould then claim to have won the Moon race, making an actual lunar landingirrelevant.9Thispossibilitylenturgencytoflyingamannedlunarmissionassoonaspossible, even one that simply orbited, rather than landed on, the Moon. So, justbeforeChristmas in1968,Apollo8orbited theMooncarryingFrankBorman, JimLovell,andBillAnders.Althoughitwasnotevidentatthetime,theflightofApollo8effectivelywontheMoonracefortheUnitedStates.

Thenext twomissions qualified theApollo lunarmodule inEarth orbit and inlunarorbit.Then,onJuly20,1969,Apollo11landedtwomenontheMoon.Therewere a fewheart-stoppingmomentswhen the ship’s computer sent theApollo 11LMEagletowardalarge,block-strewnlunarcrater,butastronautsNeilArmstrongandBuzzAldrinsuccessfullyoverrodetheautomaticsystemandlandedsafely.Initialconcernsaboutpossibledangeroussurfaceconditionsweresoondispelledasthecrewconducted a successful 2.5-hour exploration of their immediate landing site. Theycollected rockand soil samples, laid out experiments, andverified that the surfacewasbothstrongenoughtosupporttheconsiderablemassoftheLMaswellasotherequipment. The world watched as they demonstrated what it was like to movearound on the Moon in one-sixth the gravity of Earth. Armstrong made anunreported traverse to a blocky crater that he had flown over during his landingapproachandobservedthebedrockinthecraterfloor.Twenty-twohourslater,thetwo-man crew blasted off the Moon’s surface to rendezvous with Mike Collins,orbitingtheMoonintheCommandModuleColumbia.Withthecrew’ssafereturntoEarthafewdayslater,Kennedy’sdaringchallengetoAmericaeightyearsearlierwasfulfilled.

Next came the question of what to do with the remaining Saturn rockets and

Apollohardware, the surplus equipment thathadbeenprocured in the event thatmore than a single attempt would be needed to successfully land on the Moon.Initially,Apolloengineersplannedformorelunarmissionsandultimatelyahumanmission toMars.However, it soonbecameapparent that thenationalwillwasnotinclinedtowardadditionalhumanexplorationbeyondtheMoon—oreventoit.Anambitiousprogramtopushtheboundariesofhumanreachintospacewasshelved.10Apollocontinuedforafewmoreflights,butlunarbasesandMarsmissionswerenotinthecards.OurfocusshiftedtocompletingtheApolloprogram,thentodevelopingareusable transport-to-orbitvehicle forpeopleandcargo—theflightprogramthatdesigned,built,andoperatedthespaceshuttle.

Despite the political decision to abandon the capabilities of the Apollo-Saturnsystem, NASA was able to wrangle permission to fly out part of the remainingoriginal plan for Apollo lunar exploration. Several interesting landing sites wereselected for thesemissions,most ofwhich had advanced capabilities and tools forexploration.Evenwithsomenotablemissionproblems,flightandsurfaceoperationssteadilyimproved.Despitebeingstrucktwicebylightningduringliftoff,Apollo12successfully landed on the Moon in November 1969. This mission validated thetechnique of pinpoint landingby setting theLM Intrepid downwithin ahundredmetersofSurveyor3,apreviouslylandedroboticprobe.Thistechniqueallowedustosafely land at future sites of high scientific (but dangerous operational) interest.Afterthedisasterandnear-lossoftheApollo13mission,followingtheexplosionofanoxygentankinitsServiceModule,whichcancelleditslandingontheMoon,theApollo14 crew traveled to thehighlandsofFraMauro in early1971.Here itwasexpectedthattheywouldfindmaterialthrownoutfromthelargest,youngestimpactbasin, the Imbrium Basin. From this site, the astronauts returned complex,multigenerational fragmental rocks called breccias, parts of which dated to theearliesteraoflunarhistory.

On the final threeApollomissions (15, 16, and 17), the astronauts spent longertimes on the surface and possessed greater capability for exploration.11 The firstthreelunarlandingshadnosurfacetransport,sothecrewshadtostaywithinafewhundredmetersof theirLMandcouldnot remainoutside the spacecraft formorethan four to five hours at a time. The next three landings used more capablespacecraftandeachmissioncarriedasurfacerover—asmallelectriccartstrappedtothe outside of the LM. Once they were on the surface, the cart was taken off,unfolded,andthendrivenby thecrewto locales severalkilometersawayfromthelandingpoints.Inaddition,aredesignedspacesuitallowedmoonwalksofuptoeighthoursduration.Consequently,anextraordinaryamountofhigh-qualityexploration

wasconductedontheselattermissions.Eachsubsequentmissionimproveduponthetotaldistancetraveled,theamountofsamplescollected,theexperimentsperformedandthedatagathered.Thesewerethe“J-missions,”andbecauseofthem,theApolloprogramwrotegreatchaptersinthehistoryofhumanexploration.

Figure2.1.ObliqueviewoftheHadley-Apennineregion,landingsiteoftheApollo15missionin1971.Thesite

isattopleft;thesinuouschannelnearthetopisHadleyRille,achannelcarvedbyflowinglava.(Credit2.1)

Apollo15,thefourthmannedlunarlanding,wassenttotherimoftheImbriumbasin, at the base of an enormous mountain range called the Montes Apenninus(Figure2.1).ThemissionoccurredbetweenJuly26andAugust7,1971.AstronautsDaveScottandJimIrwin spent threedaysexploring themountainsand themareplainthatsurroundedthem.ThelandingsitewasalsonearRimaHadley,awinding,sinuous canyonbelieved tohavebeen carvedby flowing lava.With theApollo 15

astronauts well trained in the sciences, especially field geology, this missiondemonstratedanewandgrowingsophisticationinlunarexploration.Theastronautsfoundandreturnedafragmentoftheoriginallunarcrust,the“GenesisRock,”andan unusual emerald green glass, created by volcanic fire fountains eruptingmorethan three billion years ago.They also used a power drill to recover a core of theupperthree-metersoftheregolithatthelandingsite.

Figure2.2.Apollo16CommanderJohnYoungexploresthegeologyoftheDescartesHighlandslandingsite.The

samplesanddatareturnedfromtheApollomissionsaretheprincipal sourcesofdetailed informationon lunar

historyandprocesses.(Credit2.2)

Continuinginthismodeofsurfaceexploration,theApollo16missionvisitedthecentral lunar highlands inApril 1972.Veteran astronaut JohnYoung (Figure 2.2)and rookie Charlie Duke explored two large impact craters situated in themountainous Descartes highlands region, northwest of Mare Nectaris. Againstexpectations of finding volcanic ash flows, the crew discovered instead that the

highlands are made up of ancient rock debris, shattered and broken by eons ofcataclysmic, large-scale impacts.Although theastronautsdidnot find theexpectedvolcanic rocks, the results of this mission led us to a better understanding of theimportanceof impact inthecreationofthelunarhighlands.ThebrecciasfoundattheDescartes sitemay have come from one of the largemultiring impact basins,suchasthemagnificentOrientalebasinontheMoon’swesternedge.

IlluminatingtheFloridalandscapewithabrieffalsedawn,thelastApollomissionto theMoon,Apollo17,was thefirstnight launchof theprogram.Thismission isrenowned for the first flight of aprofessional scientist to theMoon,LMpilot andgeologistJackSchmitt.HeandGeneCernanspentthreedaysexploringtheMoon’svalleyofTaurus-LittrowontheeasternedgeofMareSerenitatis,inalowregionofsmooth mare lavas situated between two enormous basin massifs. They foundancientcrustalrocks,oldmarelavas,andmostspectacularly,orangesoil(fineorangeandblackglassparticles,piecesof lunarasheruptedfromalavafirefountainover3.5billionyearsago).Themagnificentsceneryofthelandingsiteandtheabundantscientific return from theApollo17missionwas a fitting conclusion to theApolloprogram.The380kilogramsof lunarrockandsoil in thesamplevaultsatNASA’sJohnsonSpaceCenterinHoustonarealastingscientificlegacyandtestamenttotheachievementoftheApolloprogram.

Post-ApolloLegaciesThenitwasover.WhenthelastcrewdepartedtheMoononDecember14,1972,noone knew when, or if, humans would return. Forty years on, Apollo 17 MissionCommanderGeneCernanremarkedthatheneverwouldhaveimaginedwewouldstill be looking forward toman’s return to theMoon.Willwe go back before thefifty-year milestone, or was it all just a big, one-time stunt? Did Apollo give ussomething of lasting value?What is the legacy of theApollo program?AndwhatdoesithavetotellusaboutourfutureinspaceandaboutAmericaasaspacefaringnation?

The scientific legacy of the Apollo program is remarkable. The lunar sampleshavebeenstudiedmoreintenselythanalmostanyothercollectionofmaterialinthehistoryofscience,withsomerockstakenapartatombyatom.Thesesmallpiecesofanother world have a scientific value not present in meteorites because we knowexactly where they come from on the Moon, and that information allows us tointerpret their history in a broader, regional-to-global context. By reading thehistorical recordfound in the lunar samples,wehavereconstructed thestoryofan

ancientworld,onewhereentireglobesof liquidrockcrystallized to formthecrustandmantleoftheMoon.Thisepisodewasfollowedbyanintensebombardment—giant impactsthatformedthelargeoverlappingcratersandbasinsofthehighlandsurface. Remelting of the deep interior createdmagmas that forced their way upthroughthemantleandcrust,eruptingontothesurfaceasextrusive lavaflows.Insome cases, the amount of volatiles dissolved in the liquid rockwere so great thatspraysofmoltenrockshotintospace,thenquicklycooledintothefineglassspheresthatmakeupthedarkashdepositsoftheMoon.

TheimpactbombardmentoftheMoonwasveryintenseearlyinitshistory,buttapered off drastically around 3.9 billion years ago and continues at a very lowintensity to this day. Most of the debris hitting the Moon now consists ofmicrometeorites that constantly “rain” down upon the surface. This long-termprocesshasgroundthe lunar surface intoa finepowder.Whenthese tinyparticleshitpreviouslymadesoil,someofthesoilgrainsarefusedintoameltedmixtureofglass and mineral fragments called agglutinates. Because the Moon is exposeddirectlytospaceandpossessesnoglobalmagneticfield,itssurfaceisimplantedwithsolar wind gases—particles emitted by the Sun and galactic cosmic rays, mostlyprotons,orhydrogenions, that induceradiationdamageintheMoon’sdustgrains.Thus,althoughthegeologicalevolutionof theMooncontinues to thisday, surfaceerosionhappensatanextremelyslowpace,aboutacentimetereverytwentymillionyears.

From study of the lunar samples, we now understand the telltale signs ofhypervelocityimpact,whichincludebothchemicalandphysicaleffects.Chemically,we can detect the small addition (on the order of a couple percent) ofmeteoriticdebris in the lunar soil in the form of excess amounts of siderophile (iron-loving)elementssuchasnickelandiridium.Physically,inadditiontotheshock-meltedglassagglutinates(mentionedabove),wealsoseeshockdamagetothemineralgrainsoflunar rocks. The common mineral plagioclase is often turned into glass calledmaskelynite by impact shock, a transition that occurs without melting. Otherfeatures, diagnostic of the passage of a shock wave, include cracks, mosaicism(shattered grains that arrange themselves into geometric patterns), and lines ofplanar deformation. All of these chemical and physical features are found in andaroundterrestrialimpactcraters.TheiroccurrenceinlunarsamplesverifiesthatthecratersoftheMoonareofimpactorigin.

An interesting and important consequenceof this science onlybecameapparentseveral years after the end of the Apollo lunar missions. Working with marinesedimentary rocks in Italy,geologistWalterAlvarezwanted toknowtheir ratesof

deposition. His father, physicist Luis Alvarez, suggested that he measure theconcentration of the element iridium in the rocks. Iridium is a rare element inEarth’scrust,butitismoreabundantinmeteorites.HisthoughtwasthatmeteoriticdebrisconstantlyrainsontoEarthataknownrateandthatitcouldserveasaclockformeasuringtheratesofcarbonatesedimentationontheseafloor.

When the iridiumwasmeasured, surprisingly large amountswere found in theclaylayerthatmarkstheendoftheCretaceousEra.ThisCretaceous-Tertiary(KT)boundary is demarked by a thin clay layer all over theworld and is the youngesthorizon belowwhich dinosaur fossils are found. This discovery advanced the ideathatamassivemeteoriteimpactsixty-fivemillionyearsagowasresponsiblefortheextinctionofthedinosaursandseveralotherfossilfamilies.12Later,smallgrainsofshock-deformedquartzwerefoundwithintheKTclaylayer,supportingtheideaofalargebody impactoccurringat that time.Subsequently, itwas found that in somecases,similarboundarylayersthatmarkedmassextinctionsinthegeologicalrecordalsocontainedevidenceforlargebodyimpacts.

This connection was made by recognizing the critical defining evidence forhypervelocityimpact,aprocesslearnedfromthecollectionandstudyoftheApollolunar samples. Itwas often claimed in the immediate post-Apollo period that theMoonefforthadallbeenfornaught,scientifically.Itwasthoughtthatwegotsomerocks and some ages for a few ancient events in the history of theMoon—but sowhat?That “sowhat” is now recognized as a revolutionary paradigm shift in ourunderstanding of the significance of impact in Earth history. We now view theprocess of the evolution of life on Earth from a new and unexpected perspective.Because we journeyed to the Moon, a new concept of how life may evolve wasdiscovered.

Mostofwhatwenowknowaboutthetimelinefortheoriginandevolutionofoursolar system is tied to facts obtained from our study of the Moon. Results fromApolloscientificworkcarryoverintoallofplanetaryscience.Theconceptofalateheavybombardment(thatis,theapparentincreaseinthecrateringratebetween4.0and 3.8 billion years ago) and estimates of the timescales upon which events onMars,Mercury,andotherobjectshaveoccurredareallreliantonthedatesprovidedby the Apollo lunar samples. Additionally, when requesting lunar samples,investigatorshadtoshowtheycouldmaketheiranalysesonthesmallestamountofmaterialpossible.Thisstringentrequirementforcedscientiststodeveloptechniquescapableofanalyzingextremelysmallamountsofmaterial.Thisworksucceededtosuch an extent that fully valid analyses are now done onmere specks of dust. Inaddition, because some sampleswerevery complex, such as the impact breccias of

thehighlands,newtechniquesweredevelopedthatcanrevealtheinteriorstructureof such aggregate rocks using X-ray tomography, a method similar to magneticresonanceimaging(MRI)oftheinteriorofthehumanbody.

The political legacy of the Apollo program was no less significant than itsscientific one. Despite subsequent claims to the contrary, it is now clear that theSoviets had accepted Kennedy’s challenge of sending a human to the Moon andreturning him safelywithin the decade.13 The race to prove the superiority of anideology had been joined. Each country needed to harness greater technology andscience inorder towin.Thisbreathlesscompetition inspacewasconductedwithaseriousness that we can scarcely credit these days, with each new “first” beingheralded as the key to space success, and, by inference, global domination. TheSovietsorbitedthefirstsatellite,thefirstman,thefirstwoman,andwerefirsttohittheMoonwithaman-madeobject.Theyorbitedthefirstmultiple-mancrew,andin1965,oneoftheircosmonauts,AlekseiLeonov,madethefirst“walkinspace”whenhe floated outsidehis spacecraft.America stumbled at first but rapidly caught up,matchingmostSovietachievements.Soonwebeganmakingourownspacefirsts—thefirstrendezvousanddockinginorbit,thefirstlong-durationspacewalks,andthefirst successful flight of the giant Saturn V booster. But everyone knew the truehigh-stakesmeasureofsuccesswastobethefirsttoreachtheMoonwithpeople.

WhileAmericanswereenjoyingthetrillofvictorywiththeepicflightofApollo11,theSovietswerehavingsomedifficulties.TheSovietMoonrocket,thegiganticN-1,avehiclecomparableinsizetotheAmericanSaturnV,failedallfourtimesitwaslaunched.14Thesedisasters,keptsecretfortwenty-fiveyears,sealedthefateoftheSovietMoonprogram.Withoutanoperationalheavyliftboostertodelivertheirspacecraft, no Soviet lunar mission was possible. American democracy and free-marketcapitalismhadoutmatchedtheUSSRandwontheMoon.

In programs of vast technical scope, particularly those requiring the practicalapplication of high technology such as high-speed computing to very complexproblems,Americanshadshowntheworldbothdoggeddeterminationandtechnicalprowess for accomplishing whatever they set as their goal. The Soviets viewedAmericaashavingachievedthroughacombinationofgreatwealth,technicalskill,andresolutedeterminationanextremelydifficult technologicalgoal,onethat theythemselveshadvigorouslyattemptedbuthadfailedtoachieve.America’svictoryofgetting to theMoon first andexploring its surface carriedover, later figuring inamoreseriousconflictbetweentheUnitedStatesandtheSovietUnion.

In 1983, President Ronald W. Reagan called upon the scientific and technicalcommunityoftheUnitedStatesandthefreeworldtodevelopasystemtodefendthe

country against ballisticmissiles, one thatwouldmakeAmerica and othernationsfree from the fear of nuclear annihilation. This program, the Strategic DefenseInitiative (SDI), was specifically conceived to counter the prevailing strategicdoctrineofmutuallyassureddestruction(MAD),wherebyanationwouldneverstartanuclearwarbecause itwould fear its owndestructionby retaliatory strikes.Theprice of peace in a MAD scenario was to live in a permanent state of fear. Thepromise of SDIwas to eliminate that fear byhaving a systemdesigned to defendcountriesfromnuclearmissileattack.

TheStrategicDefenseInitiativewasroundlycriticizedandbelittledbymanyinthe West who considered it “destabilizing.” Numerous scientists, including thosewho had previously done weapons work, criticized it as “unachievable.” Armscontrol specialists decried “Star Wars,” as they called it, as provocative and anescalation of the nuclear arms race. Reagan did not retreat and insisted that SDIproceed. The number one foreign policy objective of the SovietUnion in the lastyearsofitsexistencewastheeliminationofSDI.ThefamousReykjavikSummitof1986 collapsed on this very point when Reagan would not agree to cripplingrestrictionsonSDIdeploymentinexchangeformassivecutsinballisticmissilesbyGorbachevandtheSoviets.15

IfthebulkofacademicanddiplomaticopinionwassoaversetoSDIandtheveryideaofmissiledefensewasso“unworkable,”whythendidtheSovietUnionfightsolongandfiercelyagainstit?Clearly, itwasbecausetheleadersoftheSovietUnionwere convinced that SDIwouldwork—that theUnited States always achieved itsstatedgoals.BecauseAmericahadattemptedandsuccessfullyachievedthedifficultanddemandingtechnicalgoalofreachingtheMoon,itmadeanysimilargoalthatwesetouttodoseemequallyachievable.Moreover,thiswasagoalthattheSovietsthemselveshadattemptedandfailed toachieve.Withthespecterof theAmericanApollovictoryfreshintheirminds,theSovietshadnochoicebuttospendwhateverresourceswerenecessary to competewithReagan’sSDIprogram. In theend, theywentbankrupt,andtheircommunisteconomycollapsed—averyrealandpracticalconsequenceofAmerica’ssuccessfulApolloprogram.16

BegunasastrategicColdWargambitunderPresidentKennedy,Apolloandtherace to theMoondemonstrated to theworld the superiority ofAmerica’s free anddemocraticwayoflifeoverthatofourcommunistadversaries,anachievementstillnot fully appreciated today. America had achieved technical credibility from theamazing success of the Apollo program. When President Reagan announced SDItwentyyears later, theSovietswereagainst it,notbecause itwasdestabilizingandprovocative,butbecausetheybelievedwewouldsucceed.Thatsuccesswouldrender

their vastmilitarymachine, assembled at great cost to their people and economy,obsoleteinaninstant.Amongotherfactors,thishastenedtheendoftheColdWarinAmerica’s favor. Thus, the original geopolitical goals of the Apollo programwereonceagainrealized,andinamannerundreamedoffiftyyearsearlier.

The story becomes less definitive and not completely positive when evaluatingApollo’s legacy to the idea of human spaceflight. During the era of the Apolloprogram,Americalearnedhowtojourneyinspacewithpeopleandmachines.Theaccumulation of such knowledge was not the result of any systematic attempt toacquire it for its own sake, butwas developed and acquired because of need. Thetight schedule dictated by a decadal deadline, coupled with the clear geopoliticalneedtodemonstrateAmericantechnicalsuperiority,madereachingcertaintechnicalmilestonesessential.Welearnedhowtodoorbitalrendezvousbecauseweneededtomaster that skill—and quickly. This lesson has been lost on many current spacepolicymakers:theacquisitionoftruespaceflightcapabilityresultsfromtheattempttofulfillamission,notfromvaguedirectivesto“developtechnology”sothatwecaneventually“gosomewhere.”

TheApolloprogramarchitecture—thelegacyoflaunchingamission“allup”inoneortwolaunchesthatdeliverallthepiecesneededforasinglemission,discardingtheexpendablehardwarealongtheway—persistsinthemindsofmostspacepolicymakersandplannerstothisday.WhilethisapproachworkedforthefulfillmentofApollo’s limited primary objective (“Man-Moon-Decade”), it is not conducive todevelopingalong-term,permanentspacefaringcapability.ThephysicsofspaceflightdictatethatyouusemostofyourrocketpropellanttosimplyachievelowEarthorbit,withlittle,tono,fuellefttogobeyondit.Apollodefiedthe“tyrannyoftherocketequation”17throughbruteforce,bylaunchingafullyfueledSaturnIV-Bstagethatcouldthrowsomefifty-fivetonsalongatranslunarpath.Togofarther,ortogowithmorecapability,requireseitheramuchlargerlaunchvehicle,multiplelaunchesofaheavy lift vehicle, or the development of propellant depots in space. Thesedepressing mathematics rapidly tally up to an infeasible launch rate, along withcomplexorbitaloperationsneededtoassemblean interplanetarycraft.Yet,exactlysuchacumbersome,impractical,andexpensiveapproachispartofthecurrentNASADesignReferenceMissionforahumanmissiontoMars.18

Forthirtyyears,followingtheendofApollo,theenormouslogisticalrequirementsfor sending human missions beyond low Earth orbit (LEO) made most mannedspaceactivitythereunthinkable.Initsplace,otherideasbegantoemerge—conceptsdesigned to take advantage of what space had to offer in terms of creating newcapability from what we could find out there. Additionally, a more incremental

approach was sought, whereby the pieces would be reusable, smaller, and lessexpensive.Inpart,thedevelopmentofthespaceshuttlewaspursuedfortheseveryreasons.Althoughtheshuttlewasnotcompletelysuccessfulinobtainingthispartofits various mission goals, the idea of an incremental program, developed usingsmaller,reusablepieces,remainsattractivefromavarietyofperspectives.

The cost of the Apollo program still generates a lot of discussion.19 The entireprogram cost an estimated $25 billion in 1965 dollars (about $200 billion in 2014dollars). However, that number includes the construction from scratch of anenormousmaterial infrastructure, suchas theNASAfieldcentersand the facilitiesused to test and stage the lunarmissions.Muchwasmade at the time about the“misplacedpriorities”of the spaceprogram,as if the cancellationofApollowouldcureaplethoraofsocialills.LookedatfromtheperspectiveofendingtheColdWarstrugglewiththeSovietUnion,theracetotheMoonwasverycost-effective.

However,therewasanotheraspecttoApollo,onethatconstrainsourmeaningfulprogressinspacetothisday.OneofApollo’sbanefullegacieswastheentrenchmentofthenotionofexplorationasapublicspectacleorcontest,designedtodistractandexcitethepublic.AlthoughanattemptwasmadetojustifytheracetotheMoonintermsoftechnicalspinoffbenefits,sucheffortswerealwayssubjecttothecriticismthattechnicalinnovationwouldhaveoccurredanyway,withoutaspaceprogram—an irrefutable proposition because the counterfactual cannot be demonstrated.Instead,supportersofambitiousspaceeffortshavespentthelastfiftyyearstryingtoconvince policymakers that the country needs challenging and “exciting” goals toengageandinspirethepublic.Thispanemetcircensesmindsetremainsafixtureofmodern society and is an especiallywell developed standardusedby themedia toevaluate(andusually,denigrate)proposednewspaceinitiatives.

Thisentrenchedwayofthinkingisineffectualandcounterproductive.Bymakingthehumanspaceprogramintoanoverblown“realityshow,”weareforeverdoomedtoperformsingularandunconnectedstuntsofnolastingvalue.Rationalesforspaceexplorationthatrequirepublic“excitement”toooftenrelyonbeingthe“first”todosomething. This involves promoting distant, unachievable goals such as humanmissionstoMarsinsteadofreachable,near-termgoalsanddestinationsthatwecouldaccomplish on reasonable timescales, such as a lunar outpost. Current concepts ofpublicsupportforspaceexplorationarebasedonafalsereadingofpublicsentiment:Mostpeoplesimplydonotcareaboutspace,soattemptsto“excite”themareboundto fail. There are always vocal proponents for space, individuals and small groupswhohold strong opinions, but too often lack thenecessary technical knowledge tounderstandwhatisfeasible,againstwhattheydesire.

Despite this problem, a case still can be made that an affordable, long-termstrategicgoalforhumanspaceflightnotonlyexistsbutcanbeadoptedandattainedwithout breaking the national bank. After fifty years of human spaceflight, werealize that there are tasks in space beyond the capabilities of roboticmachines—tasksthatrequirehumanpresence.Peoplemustbepresenttointeractphysicallyandintellectually with the space environment in real time to accomplish some goals,such as scientific field exploration and the repair and maintenance of complexmachines.Weneedtodevelopasystemthatultimatelypermitsustogoanywhereweneed,withhumansandmachines,toaccomplishwhatevergoalsmaybedesired.A largeambition, tobesure,butwealreadyhavesigns that thecreationof suchaspacesystemispossible.

How?Theanswerisrightnextdoor.

T

3AfterApollo:AReturntotheMoon?

he two decades following the end of the Apollo program are the wildernessyears of lunar exploration. Despite repeated attempts and endless discussion,

except for flybysby spacecraft on theirway to somewhereelse,between1972and1994,therewerenoAmericanmissionstotheMoon.Still,wecontinuedtostudythesamplesanddatareturnedbytheApollomissions.Therewasoccasionalexcitementwhenaninternationalmissionreturnednewlunardataorinformation,orwhentheoddAmericanspacecraftacquiredsomenewdataas it flewpasttheMoon.Duringtheseyears,wemadesignificantadvancesinourunderstandingofthenatureoftheMoon and with it, gained a better understanding of the requirements for livingthere,allwhichaddedtothefrustrationofadvocatesdesiringareturntotheMoon.

TheentireAmericanspaceprogramsufferedanidentitycrisisintheearly1970s.FollowingthesuccessandhooplaofwinningtheracetotheMoon,Americaseemedto lose interest in space. At least, that’swhatwewere told had happened.1 SocialcommentatorsdecriedtheeffortsoftheAmericanspaceprogram,describingthemasirrelevant and a waste of money. Defenders of the space program spoke abouttechnicalspinoffsandsocietalinspiration.ButthemostinspirationalaspectofApolloturnedouttobethemosteffectiveoneusedagainstit:thestrikingimageofanearlyfullEarthrisingabove the lunarhorizon, first seenduringtheApollo8missionofDecember 1968. Similar images were subsequently captured by each succeedingmission. The view of a blue andwhite Earth suspended in black space above thebarren,lifelessMooninitiatedthemodernenvironmentalmovement,which,inturn,quickly blossomed into a Luddite, anti-technological crusade. People wereencouragedtoeschewtechnology,forswearamoderncivilizedlifestyle,andgobacktotheland.

Duringthistime,humanspaceflightwasfocusedexclusivelyonlowEarthorbit.The development of the space shuttlewas billed as a program thatwould “makespaceflight routine.” Many equated “routine” with “cheap.” While the programachievedtheformer,itdidnotattainthelatter.Withthespaceprogrameffectivelycappedatlessthan1percentofthefederalbudgetperyear,therewasnomoneytodevelophumanmissionsbeyondlowEarthorbit(LEO).Whiletheshuttlehasbeenlabeledapolicyfailure,2intruth,itofferedseveraluniqueandvaluablecapabilities,

including some that arenot availablenow, or even contemplated tobepresent onanyfuturemannedspacecraft.Theshuttle’sdevelopmentwasmarkedbytechnicaldifficultiesandfiscalchallenges,butinhindsight,itishardtoseehowitcouldhavebeendoneanybetterormoreinexpensively.

In addition to developing the shuttle, NASA used surplus hardware from theApolloMoonprogramtomakeSkylab,America’sfirstorbitingspacestation.3Skylabwas a Saturn third stage (S-IVB) with its interior configured into a living andlaboratoryspaceforthreecrewmemberstoinhabitforperiodsofuptoninetydays.The laboratory, launched on a Saturn V on May 14, 1973, quickly encounteredproblems when during ascent its thermal shield was torn away. Skylab alsoexperiencedsignificantproblemswhenone solararraywas tornoffduring launch,and theotherdidnotdeployonarrival inorbit, pinned to the sideof the labandunable togenerateelectricalpower.Asa result,when the crewarriveda fewdayslater,theworkshopwasseverelyunderpoweredandoverheated.Sosevereweretheseproblems that they threatened to cause an early termination of the first SkylabmannedmissionandtheSkylabprogramasawhole.

Skylab 2’s crew, consisting of Pete Conrad, Paul Weitz, and Joe Kerwin, wentstraight towork troubleshooting these problems. They erected a sunshade parasolthatallowedthevehicletoremaincoolundertheglareofsolarillumination.Theyconducted spacewalks to free thepinned solararray.Once itwas fullydeployed, itstarted producing electrical power. The crew spent a record-setting twenty-eightdays in orbit, and thanks to their sustained and heroic efforts, Skylab was saved.Duringtheirlong-durationmission,theyactivatedon-boardexperiments,conducteda variety ofmedical experiments,mapped theEarth, andmade solar observationswiththeuseofaspecialtelescope.

TwoadditionalSkylabcrewsfollowed,spendingperiodsoftwoandthreemonthsrespectively in the orbiting space station. The last crew left the station in aconfigurationthatwouldallowittobevisitedandusedbyafuturecrewoftheyet-to-fly space shuttle. Inorder toattachnew solararraysandadockingmechanism,andtooutfitthelaboratoryforusebyuptosixorsevencrewmembers,plansweredevelopedtoflyacoupleofshuttlemissionstoSkylabin1979–80.However, thesemissionsneverflew.Theshuttlehadrunintodevelopmentproblems,whichdelayeditsfirst launchuntilwellafter1980.Bythelate1970s,enhancedsolaractivityhadheatedandexpandedtheatmosphereoutward, increasingthedragonSkylab.Thisincreased dragmade the orbit of Skylab decay at amuchhigher than anticipatedrate, eventually leading to an uncontrolled reentry of the lab on July 11, 1979.AlthoughNASAattemptedtosteerthevehicletouninhabitedocean,largechunksof

debrisfellontheoutbackinsouthwesternAustralia.Fortunately,noonewasinjuredandtherewaslittlepropertydamage.

Oncebelievedtobethebeginningofalong-termeffort,onethatwouldseeApollospace hardware conducting a wide variety of missions throughout cislunar space,Skylabnow represented the shriveled remnant of our ambitiouspost-Apolloplans.By using the basic building blocks of Saturn and the Apollo command and lunarmodules, this program, dubbed Apollo Applications, had envisioned space stationswithorbitalservicingvehicles,lunarorbitalobservatories,andevensurfaceoutposts.The problem for Apollo Applications was that it needed the Apollo and Saturnproduction lines toremainopenandthatrequiredmoremoneythanCongressandthePresidentwerewillingtomakeavailable.Theshuttlehadbeensoldpoliticallyonthepromiseofmakingspaceaffordable.Sincetherewasnoaffordablewaythatbothcouldbeinproductionatthesametime,somethinghadtogo.Withthedemiseof theApollo-Saturnproduction lines,plans formissions throughoutcislunar spaceended.

Thespaceshuttlewasoriginallydesignedtobecomethefirstpieceofanentirelynew line of reusable, extensible space hardware. The shuttle, as developed, couldonlygotoandfromlowEarthorbitbut itsdesignerscertainlyhadnointentionofstopping there. The official name of the shuttle was the Space TransportationSystem (STS), aname chosen to convey that theEarth toLEOorbiterwas only asingle piece of a larger, more comprehensive system—a system that included apermanent space station and an orbital transfer vehicle, a space-based “tug” thatcouldhaulsatellitesandotherpayloadstohighorbitsaboveLEO.ButthatconceptwasgraduallyforgottenaswebusiedourselveswithspecializedmissionstoLEOandwith the monumental task of building a new space station—NASA’s principaldestination in space for the 1980s—assembled on orbit over time from piecesbroughtupbytheshuttle.4

Theendof theApolloprogramwas followedby thedoleful codaof theApollo-SoyuzTestProject(ASTP),ajointflightofAmericanandSoviethumanspacecraftdesignedtoinaugurateanewageofcooperationinspaceandensurepeaceonEarth.5TheApollocrewconsistedofveteranApolloastronautTomStaffordcommanding,flyingwithVanceBrandandDekeSlayton,whowas finallygettinghis chance inspaceafterbeinggroundedforthirteenyearsbecauseofaheartmurmurdetectedin1962.TheyrendezvousedinspacewithaSovietSoyuzspacecraftcommandedbythefirstmantowalkinspace,AlexeiLeonov,andhiscopilot,ValeriKubasov.Thetwospacecraft docked using a common berthing mechanism provided by the UnitedStates.Afterexchanginghandshakesandsmiles,thecrewdriftedovertheEarthin

anextendeddemonstrationof goodwill, good spirits, and ferventhopes for futurecooperationinspace.CooperationwouldeventuallycometwentyyearslateraftertheIronCurtainwasdismantled,andwithittheSovietUnion.

With the splashdown of theASTP on July 24, 1975, Americawaswithout anymeans to send people into space until the new space shuttle system becameoperational.Theshuttlewasacomplicatedanddelicatevehicle.Ithadtowithstanda violent launch and ascent aswell as a harrowing reentry speed ofMach 25, allwhile retaining a low enoughmass tomake the entire systemwork. Low-weightsilica tiles that were glued onto the outside of the orbiter airframe provided thenecessary thermal insulation to block the searing heat of reentry. These thermalprotectiontilescausedongoingandendlessheadachesovertheentirethirtyyearsofshuttleoperations.The thermal tileswereboth fragile (likely tobreak ifdropped)andtendedtofallofftheairframe(findingtherightbondingagenttogluetheminplacetooksometime).

Severaldroptestswereconductedinwhichashuttlewasreleasedfromitscarrier747aircraftandallowedtoglidetothesurfacebeforethefirstspaceshuttleorbitalmission launched inApril1981.AstronautsJohnYoungandBobCrippenflewthefirstshuttleorbiterColumbiaintospaceandsafelyreturnedittoEarth.6Thatflightverifiedthesystem’sbasicdesignandstartedthenextchapterinthehistoryoftheUS spaceprogram. Shuttle flights continued apace throughout the 1980s, as flightafterflightdeliveredsatellitestotheirorbitsandflewavarietyofEarthobservationandmedicalexperiments.TheshuttledesignallowedittobefittedwithSpacelab,acylinder-like module roughly the size of a school bus that was carried inside theshuttlecargobay.SinceSpacelabflewonlyduringashuttlemission,itsoperationinorbitwaslimitedtoabouttwoweeks,thelimitoftheamountofreactantsthatcouldbecarriedfortheshuttle’sfuelcellsandfuelforattitudecontrol.

Inadditiontothesehighprofilecivilspacemissions,severalearlyshuttleflightswerededicatedtothelaunchofnationalsecuritypayloads.Thiswasaconsequenceof promoting the shuttle to the Congress as the universal replacement for allexpendablelaunchvehicles.Theargumentwasmadethatshuttlecouldhandleanddeliveronorbitanyandallpayloads—scientific,commercial,andnationalsecurity.Estimatesmadeduringvehicledevelopmentsuggestedthatasmanyasfiftyflightsperyearwerepossible.Butaftertheshuttlebecameoperational,thevehiclerequiredmuchmorerefurbishmentbetweenflights(andconsequently,moretimetopreparefor launch) than had been anticipated. At peak rates of activity, the shuttle flewabouteight tonine timesperyear.While this flight ratewasquite respectable forsuchacomplexsystem,itwasnotthelevelofactivityenvisionedanddesiredinthe

earlydaysoftheprogram.Despitetheoperationalsuccessesofthespaceshuttleprogram,agradualsenseof

ennui developed within the space community. The program’s seemingly endlessseries ofmissions to LEO had become its own justification, and it was perceived,perhapsunfairly,asadeadend.Initially,thiswasbecausetherewasnospacestationto support.When theadditionalpiecesof theSTS“system”didnotmaterialize, itmeantwehadnostation,noorbitalmaneuveringvehicleandnolunartug.Thus,theSTShadbecomeasystemwithjustonepiece,anditwasgettinghardertojustifyahumanspaceprogramthatonlyorbitedinendlesscircles.

Thestasis,however,wasmoreillusionarythanreal.Despitetheshuttleprogram’sfocuson lowEarthorbit, advancedprogramplanners inHoustonhad indeedbeenthinking about follow-on steps once the orbiter became operational. In accordancewiththeclassicvonBraunarchitecture,theobviousnextstepwassometypeofspacestation.7BecauseSkylabhadbeen lost andweno longerhad theSaturnV launchvehicle, the shuttle would have to be used to assemble a space station. Using theshuttle as a delivery system meant that construction needed to be done in smallpieces,withfullstationassemblyrequiringdozensoflaunches,spreadoutovermanyyears.

Lookingback fromourvantagepointofhavinganoperational ISS, it is easy toforgetwhatamonumentalengineeringandprogrammaticchallenge thatwas.Wehadneverassembledagiant,distributed-systemsatellite inspace.Theassemblyofcomplexequipmentandfacilitiesinspacewouldrequiretechniquesthathadnotyetbeendevelopedandwereonlyvaguelyunderstood.Theassemblyrobotshadnotyetbeenconceived,letalonebuilt,andamanagerialstructurehadtobeformulatedthatcouldadapttochangingbudgets,moduledeliveryschedules,weatherdelays,andpadavailability.Fromtheirmid-1980svantagepoint,thosetaskedwiththechallengeofassemblingthestationknewthatmanymoreunknownsthancertaintieslayahead.

Having a large space station in low Earth orbit would offer more than just alaboratoryforexperiments:Ifproperlyconstructedandconfigured,itcouldbecomethe transit node for missions beyond low Earth orbit to the Moon and on to theplanets. This idea still held sway in theminds of shuttle architects who took themonikerSpaceTransportationSystemliterally.ThevonBraunarchitecture,laidoutin the famousCollier’s articles of the early1950s,8 envisioned first a space station,thenanorbitaltransfervehicle,aMoontugandlander,andfinallyaninterplanetaryspacecraft.Thisincremental,buildingblockapproachhadbeenabandonedwhenthepoliticalimperativeofbeatingtheSovietstotheMoonhadtakencenterstage,butitwasanapproachtowhichthespaceagencywantedtoreturn.

PresidentRonaldReaganannouncedplansforthenewspacestationprograminhis1984StateoftheUnionspeech.9ItwouldbecalledFreedomandwouldserveavarietyofpurposes, including laboratory researchandobserving theEarthand theuniverse,aswellasservingasatransportationnode.Initslatterrole,Freedomwouldbeequippedwithaservicingbayforsatelliterepairandserveasadeparturepointformissions from lowEarth orbit tohigh orbits typically occupiedby commercialcommunicationsandother satellites.Such transport requireda reusable, refuelablevehicle, one that could move from low orbits to geosynchronous orbit (GEO), acircular, equatorial orbit about 22,000 miles (36,000 km) high. At this altitude,satellites orbit once every twenty-four hours and thus appear stationary or traceelongated, figure-eight loops in the sky. Any ground station on the hemispherebelowthesatelliteinGEOisalwaysinradioview.GEOisextremelyimportantrealestateforglobalcommunications,weathermonitoring,andremotesensing.

ArocketlaunchedfromthesurfaceoftheEarthexpendsvirtuallyallofitsfueltoachievelowEarthorbit.Butintermsoforbitalenergy,thisisonlyabouthalfwaytogeosynchronous orbit.To get satellites toGEO, the rocketwouldhave to carry anupper stage for the final orbital transfer, thus limiting the size, and thereforecapacity, of a satellite inGEO.Additionally, a satellite inhighGEOwouldnotbeaccessiblebytheshuttle,oranyotherhumanspacecrafttodate.Whenahighorbitsatellite malfunctions, typically it is abandoned and deorbited, whereupon anentirelynewsatellitemustbebuiltandlaunched.

Having a spacecraft stationed at the low orbit space station would solve thisdilemma.Itwouldpermitcrewstotravelroutinelytoandfromthehighorbitsthatthesesatellitesoccupytoserviceorreplacethem.Butmoresignificantly,crewscouldbuild satellite systems thatwouldbemuch largerandmore capable thanany thatcouldbelaunchedonasingleexistingorplannedlaunchvehicle.IfthebuildingofFreedomweresuccessful,itwouldteachushowtobuildlarge,distributedsystemsinspace.These techniques could thenbe applied to complex satellites inhighorbits,presumingthattherewouldbeawaytogetcrewsandrepairfacilitiestothathighorbit.

AkeypieceoftheevolvingSTS,theprojectedorbitaltransfervehicle(OTV),wasdesignedtobeberthedatFreedomandavailabletotransportpeopleandequipmenttohigher orbitswhenneeded.TheOTVwas to be fueledby liquidhydrogen andoxygen brought up from Earth, at least initially. The vehicle also carried a heatshield,allowingittousethefrictionofEarth’satmospheretoslowdownthevehicleduringcloseapproachonreturntoLEO,thusrequiringonlyaminimalamountofmaneuveringcapability.Thisstrategymadethevehiclesmallerandmoreefficient.

DevelopmentofanOTVwouldbethenextlinkincreatingagenuinelyspace-basedtransportationsystem—andavehiclethatcouldroutinelyreachGEOcouldalsogototheMoon.10Despiteitsmanypotentialbenefits,anOTVwasneverbuilt.

TheLunarBaseMovement(1983–93)In1983,twoscientistsfromtheJohnsonSpaceCenter,MichaelDukeandWendellMendell, realized that if NASA developed the OTV as part of the shuttle-stationarchitecture, we would possess the means to return to the Moon. Along withphysicist Paul Keaton from Los Alamos National Laboratories, they organized asmallworkshop,whichwasfollowedbyamajorconferenceattheNationalAcademyof Sciences in Washington.11 That conference drew a large and enthusiasticattendance of engineers, scientists, and space visionaries. Over the course of threedays, theydiscussedandpondered the implicationsofa lunar return.The scopeofthemeetingvariedwidely,withsuchtopicsdiscussedasextendedexplorationoftheMoon,habitationandlifesupport,mininganduseoflocalmaterialsforoxygenandconstruction,andorbit-to-surfacetransportationandfuelingdepots.

Thismeeting initiated a large communitymovementdedicated to lunar return.Enthusiasts and advocates studied and improved their knowledge of the lunarsurfaceandmaterialsinpreparationofareturn,notinthetemporary,sortiemodeofApollo,butfor longer,morepermanentstays.Aseriesofmeetings,workshops,andconferencesover thenext fewyears fleshedoutpossible scenarios for lunar return.Muchattentionwaspaidtothepossibleuseof lunarresourcestosupportextendedhuman presence on theMoon and elsewhere in space.12 These schemes tended tofocusprimarilyontheproductionofoxygen;lunarsoilisabout45percentbyweightoxygen,althoughextractingitandconvertingitintoitsfree,gaseousformwasfoundtobeaveryenergyintensiveactivity.Moreover,theenvironmentofthelowlatituderegions of the Moon requires a long-lived source of electrical power in order tosurvivethefourteen-Earth-day-longlunarnight.Thus,studiesofpowergenerationmechanismsneeded at lunar outposts tokeep equipment andpeoplewarmduringthebone-chillinglunarnight,revolvedaroundthedevelopmentofnuclearreactors,whichwouldprovidesteady,constantelectricalpowerandheat.

All these studies concluded that while lunar habitation was possible, it wouldrequireseveralexpensivetechnicaldevelopments.Onceagain,spacedreamsranupagainstthecoldrealitiesoffiscalconstraints.Theresponsetothisrealizationtendedto focus on justifying lunar return in terms of some high-value benefit, such thatbillions of dollars of investment would be worthwhile. Such benefits typically

involved the production of clean electrical energy for the Earth. One idea was tomakesolarcellsinsituonthelunarsurfaceandcreatekilometer-sizedphotovoltaicarrayswhosepoweroutputcouldbetransmittedtoEarthviamicrowaveorlaser.Analternative conceptwas to harvest the lunar regolith for a rare isotope of helium,3He,whichcouldfuela“clean”fusionreaction, i.e.,onethatproducesnoharmfulradioactiveby-products.13Although3HeispresentonEarthasatracecomponentofnatural gas, it is found in extremely minute quantities, inadequate to fuel acommercial electrical generating industry. However, the Sun streams energeticparticles continuously.This is the solarwind,whichbypasses theEarthdue toourglobalmagneticfieldbutisimplantedonlunardustgrains.Althoughstillpresentinrelativelyminuteamountsinthelunarsoil(abouttwentypartsperbillion),studiesindicatethatsuchconcentrationsarelargeenoughsuchthat3HecouldbeharvestedfromtheMoon.Thisideacaughttheimaginationofboththepublicandthelunarreturncommunitywhenitwasfirstproposed.However,severalsignificanttechnicalprerequisites remainbeforewehavepower generation systems that use 3He,mostsignificantly,theneedforareactordesigninwhichtoburntheheliumfuel.

Amajoractivityofthelunarsciencecommunityinthe1980swasanefforttosendaroboticmissiontoorbittheMoon.Thismissionconceptfirstemergedinthemid-1970sunderthenameLunarPolarOrbiter(LPO),aperfectdescriptor.Becausetheplane of an orbit is fixed in inertial space, a satellite in polar orbit will view theentiresurfaceastheplanetormoonslowlyrotatesonitsaxis.Suchaspacecraftcouldbe configured with nadir-pointing instruments to measure a variety of chemical,mineralogical,andphysicalpropertiesoftheMoon.AlloftheApollomissionsflewinnear-equatorialorbits,soonlyabout20percentofthelunarsurfacewasoverflownandmappedwithcompositionalremotesensorsfromtheorbitingCommand-ServiceModules.BothoftheLunarOrbiterIVandVspacecraftwereplacedinpolarorbitsandcompletedaglobalsurveyoftheMoon,documentingtheirvalue.

Figure3.1.Lightingmapsof thenorth(left)andsouth(right)polesof theMoon.Onthesecomposite images,

bright areas are in sunlight for extended periods while black areas are in permanent darkness. This relation

(causedbythe1.6°obliquityoftheMoon)makescoldtrapsthathaveaccumulatedsignificantamountsofwater

iceovergeological time.The sunlit areaspermit electricalpower tobegeneratednearly continuously. (Credit

3.1)

OnecriticalpieceofinformationabouttheMoonwasmuchdebatedintheyearsfollowingApollo.No evidence forwater—past or present, on the surface or insidetheMoon—wasfoundinthelunarsamples,afindingthatledtothedogmathattheMoonwasbone-dryandthat ithadalwaysbeenso.As such, thismadethe taskofliving on theMoonmuchmore formidable and challenging.However, before theadvent of the Space Age, we knew that the poles of the Moon had some uniqueproperties.BecausethespinaxisoftheMoonisnearlyperpendicular(88.4°)totheplaneoftheecliptic(theplaneinwhichtheEarth-MoonsystemorbitstheSun),theSunalwaysappearsonor close to thehorizonat the lunarpoles. Ifyouwereonapeak, you could be bathed in constant sunlight. Conversely, if youwere in a hole(crater)atthepoles,youmightneverseetheSun(seefigure3.1).Thesedarkareaswouldbeextremelycold,sincetheonlyheattheyreceivecomesfromtheextremelylowquantitiesofheatflowingfromtheinterioroftheMoonitself.

Several studies suggested that these properties could have some dramaticconsequences. We had evidence that the Moon has been bombarded by water-bearing objects—namely, comets and meteorites—over its history. Most of thiswaterwouldbe lost to spaceordissociated in thehightemperaturevacuumof the

lunarsurface.However,ifwatersomehowfounditswayintoadark“coldtrap”nearthepoles,itwouldremainthereforever,andnoknownnaturalprocesscouldextractit.MuchspeculationwasexpendedonhowmuchicemightbeinthepolarregionsoftheMoon,butwecouldnotknowif itwas thereuntilwewent looking for it.14Apolarorbiting,remotesensingsatellite(e.g.,LPO)wasneededtodetectwhatmightbeinthosedarkareas.

Despiteitsappealonscientificgrounds,anditsobviousimportanceasaprecursorforeventualhumanreturntotheMoon,theLPOmissionwasrepeatedlypassedoverforothermissions throughout the twentyyears followingApollo. InJanuary1986,the space shuttle Challenger exploded shortly after liftoff, killing all seven of itscrew, includingChristaMcAuliffe,whowas not an astronaut but instead the firstteacher in space. The shock of this tragedywas a public relations disaster for theagency,followedbyawrenchingperiodofintrospectionandsoul-searchingaboutitsvisionandpurpose,alongwiththeaccompanyingtechnicalreviewscalleduptofixtheproblemandrestart the shuttleprogram.Inaddition toagencychaosafter theChallengeraccident,theFreedomprojectwasalsointurmoil,havingundergonetwocompleteredesignsbeforetheshuttleaccident,followedbyanotherredesignayearlater.Becauseofthemajordisruptionofthelossofashuttle,seriousconcernswereraisedabouttheviabilityofthespacestationprogram.

Tworeportswereissuedduringthemannedspaceflighthiatusofthelate1980s.The Rogers Commission, named after its chairman, former Secretary of StateWilliam Rogers, was chartered to identify the cause or causes of the Challengeraccidentandtorecommendpoliciesandprocedurestofixtheproblem.15Theothercommission had a broader task: TheNational Commission on Space (NCOS), alsocalled the Paine commission after its chairman, former NASA AdministratorThomasPaine,wasaskedtodeviseasetoflong-rangegoalsforspaceandtoidentifysomeofthestrategiesneededtoattainthem.16TheNCOSworkwasnearcompletionwhentheChallengeraccidentoccurred,andbecauseof thisunfortunate timing, itsreportwas largely ignoredwhen released.However, thePaineCommission reportwas very thorough and complete. It identified a systematic, incremental, andaffordableexpansionofhumanityintospace,forall thereasonswehaveidentifiedovertheyears—theNCOSvisionprominentlyfeaturedspaceresourceutilizationinaddition to exploration and science. It anticipated almost all of the currentarguments for space goals and destinations, and suggested that because all aredesirable in the objective sense and have their own constituencies, each can andshould be pursued via a program that incrementally develops a wide range ofcapabilities.

TheagencyrespondedtothePainereportwithaseriesofstudiesandworkshopsthroughoutthehiatusperiodinhumanspaceflight,culminatingwithareportissuedinAugust 1987 by an internal study group led by astronaut SallyRide.TheRideReportidentifiedfourmissionconcentrationareas:Earthsystemsciencefromspace,unmannedspacescienceexploration,alunaroutpost,andahumanMarsmission.17Thereportdidnotadvocateorchooseanyof thefourbut insteadfocusedonwhatbenefitsandspacefaringlegacieseachonewouldgiveus.ItsuggestedthataheavyliftlaunchvehiclewouldenablemanyoftheseactivitiesandthatanewHLV,usingshuttle-derivedhardware,couldbedevelopedquicklyandinexpensively.

RiseandFalloftheSpaceExplorationInitiative(1989–93)Problems with the shuttle solid rocket booster joints (identified by the RogersCommission)werecorrectedand thevehicle returned to flight inSeptember1988.Armedwitharenewedcapabilitytogethumanstoandfromorbitandwithreportsfrom three blue-ribbon study groups, President George H. W. Bush made thedecision to announce a new major direction for America’s space program. Muchspeculationhasbeenexpendedon theoriginsof the subsequentSpaceExplorationInitiative (SEI).18 My interpretation is simple: at the end of the 1980s and thebeginningofthe1990s,astheColdWarwaswindingdowninourfavor,concernhaddeveloped about the erosion of our national technical capabilities—the enormousdefense industrial infrastructure that won the struggle against the Soviet Union.President Bush and his advisors were well aware of this issue and the need tomaintainalevelofadvancedtechnicalinfrastructureintheabsenceoftheColdWarpoliticalimperative.Thespaceprogramhadservedthatpurposebeforeandthus,anexpandedspaceprogram—madeaffordablebytheeasingofdefenserequirements—could maintain a keen technological edge at a fraction of the level of Cold Wardefense expenditures. Curiously, the members of the Bush administrationresponsible for space policy never made this point publicly, but I know fromdiscussionswithsomeofthemthatmanyintheWhiteHousewerewellawareofitsdimensionsandimplications.

InaspecialspeechdeliveredonthestepsoftheNationalAirandSpaceMuseuminWashingtonDC,PresidentBushannounced thenewinitiativeon the twentiethanniversaryof theApollo11Moon landing.19TheSEIwaswhat spaceenthusiastshadbeenwantingsincetheApolloprogram:apresidentialdeclarationonambitiousspace goals. It called for the completion of space stationFreedom, a return to theMoon(“thistimetostay”),andahumanmissiontoMars.Thepresidentdidnotset

forth deadlines for each milestone, except that space station Freedom should becompletedwithinthenextdecadeandthatmissions to theotherdestinationsweretasksforthenewmillennium.ThepresidentaskedhisownWhiteHouseNationalSpaceCouncil to examineanddefine the technologies andarchitecturesneeded toimplementhisnewspaceinitiative.Naturally,theSpaceCouncilturnedtoNASAforassistanceinthisnewtask.

Teams fromNASAHeadquarters and the field centers were quickly assembledand charged with defining the steps, and the missions and pieces of the newprogram.Theywere tasked to report to theWhiteHousewithinninetydays.The“90-DayStudy”soonbecameinfamousasthedeathcertificateoftheSEI,althoughinhindsight,itisnotnearlyasnefariousaswidelyreportedandbelieved,andinfact,containsmuchgoodengineeringsenseandmanyclever ideas.20 Inshort, themainproblemwas thatNASAwas barely being funded at an adequate level to run thespaceshuttleprogramandtobuildFreedom.Naturally, itwouldrequireadditionalfundingifadditionalmajortaskswereaddedtoitsagenda.Suchlogicwasforgottenorignoredinanorgyofself-righteousindignationoverthe“pedestrianandbloatedapproach” of the 90-Day Study. Five alternative “reference approaches” wereoutlined,witheachbuildingoutwardfromtheshuttle/stationinincrementalstepswhile varying the rate of development and the amount of activity according toselectablelevelsofeffort.

Thebiggestproblemwith the90-DayStudywasnot the report itself, butwhathappened behind the scenes. The report deliberately did not include budgetinformation. Estimated costs were prepared so that policymakers could evaluatedifferences among the approaches. As onemight expect, once these cost numberswereleakedtothepress, thechatteringclasses insidetheBeltwaywereaghast: thenewSEIwasexpectedtocostupwardof$500billion!Whatwasalways leftoutofthese stories was that this cost number was the aggregate budget of the agencyspreadover the courseof thirtyyears, ametricagainstwhich few federalagencieswould standupwellunder scrutiny.Andgiven thenational securitydimensionofthenewSEI,suchsumswereamerefractionofthenationaldefensebudgetoverthesame period. Nonetheless, this number was widely circulated. It quickly became“canonical”andwasusedtodiscreditanddisparagethewholeideaoftheSEI.

The White House and Space Council knew that political forces outside theircontrolweretorpedoingtheirnew,majorinitiative.21Tofightthiseffect,theSpaceCouncil convened a special committee to examine the 90-DayStudy, aswell as toreview detailed alternatives prepared by industry and other federal entities. Themost famous of the latter was the proposal from Lawrence Livermore National

Laboratorytouseinflatablevehicleslaunchedonexistingexpendablerockets.22Thisproposal claimed that both a lunar return and a manned Mars mission could beconductedforlessthanone-tenththeleakedcostofthe90-DayStudy.Regardlessofthedoubtfulveracityofthatcostestimate,orthetechnicalfeasibilityoftheconcept,it drew major attention from the White House. That attention propelled thecanvassingofawidersegmentofthecommunitywithhopesitwouldgeneratenewandinnovativeideaswithwhichtoimplementtheSEIforafractionofthefundingthat NASA claimed was needed. The National Research Council, whose specialreport on the study concluded that a variety of other technical options should beinvestigated,onesthatNASAhadnotconsidered,providedadditionalsupportforamajorreevaluationofthe90-DayStudy.

In this vein, the Space Council decided to create an outreach effort thatwouldgather up the best technical ideas on how to implement the SEI from all sectors.Theseeducatedandinnovativesuggestionsandplansweretobecollected,evaluated,andhigh-gradedbya specialpanel called theSynthesisGroupanddistilled intoaplan for a magical—meaning cheap—beanstalk into space. This panel includedmembers from academia, government, and industry andwas chaired by astronautTomStafford.IwasamemberofthisgroupfromAugust1990toJune1991.TomStaffordsaidthisactivitywas“likedrinkingfromafirehose,”andIfoundthattobeanaptdescription.ThetenmonthsspentservingonSynthesiswasacrashcourseinastronautics, a course that included the benefits and pitfalls of technologydevelopmentand its role inarchitecturaldesign.Asonemightexpect, themassiveinput from the space community did not contain any “magic beans” or “silverbullets”thatwouldtakeustotheMoonandtheplanetsfaster,better,orcheaper.23And in that sense, the SynthesisGroup did not succeed.But in another sense, theSynthesisGroupadvancedourunderstandingabouttheMoonanditscrucialroleforhumanexpansionintothesolarsystem.

Twoeventsoccurredinthespringandsummerof1990thatseverelydamagedthecause of SEI. The first event involved theHubble SpaceTelescope. Although thetelescopehadbeensuccessfullylaunched,itwassoondiscoveredthatitsmainopticalelementhadbeengroundtothewrongspecification.ThismistakecausedHubble’shighlyanticipatednewimagesoftheuniversetobeoutoffocus.24Theothereventwasthetemporarygroundingoftheshuttlefleetbecauseofanunresolvedhydrogenleak. These problems, along with the release of the 90-Day Study, combined topresent the image of a space agency that was both technically incompetent andpolitically out of touch. Thus, despite giving the space agency an additional $2billionoverallintheFY1991budget,CongresszeroedouttheSEI,aclearsignalthat

NASAwasinseriouspoliticaltrouble.Thedeepantipathybetweenthespaceagencyand the White House was finally resolved with the sacking of Richard Truly asadministrator and the subsequent hiring of Daniel Goldin as his replacement.Despite attempts to initiate SEI again in the following twoyears,Congresswouldnot approve or fund it, and the initiativewas terminated following the reelectiondefeatofPresidentBushandtheadventoftheClintonadministration.25

TheClementineMissionandItsLegacy(1994)ThelunarsciencecommunitycontinuedtolobbyNASAtosendaroboticorbitertotheMoon,buttonoavail.TheirgoalwastomaptheMoon’sshape,composition,andotherphysicalproperties.Suchamissionwouldnotonlydocumenttheprocessesandhistory of the Moon but would also serve as an operational template for theexplorationofotherairlessplanetaryobjects.Acollectionofglobal remote sensingdatacouldprovidescientistswithinvaluablegroundtruthwhenusedinconjunctionwith the previously returned Apollo surface samples. The Lunar Polar Orbitermission,proposedseveraltimes,neverreceivedanewstart.Itslastincarnationwasthe JetPropulsionLaboratory’sLunarObserver, patterned after the ill-fatedMarsObservermission.ThecostreviewofLunarObservercameinataround$1billionin1990dollars.Ofcourse,itwaspassedoveryetagain.

Stewart “Stu” Nozette of Lawrence Livermore National Laboratory, anotherSynthesisGroupmember,wasinvolvedintheBrilliantPebbles(BP)programoftheDefense Department’s Strategic Defense Initiative.26 The idea behind BP was todefend the nation against ballistic missiles by launching swarms of small,inexpensive satellites, each capable of observing, calculating and plotting anintercept course to incoming missiles (the “brilliant”) and then rendering theminoperative by collision (the “pebble”). These small, three-axis stabilized vehiclescarriedimagingsensors(bothactiveandpassive)aswellasin-flightcomputersandpropulsion systems. In short, they were small but fully capable, self-containedspacecraft.

Nozette’sideawastoflyaBPtoadistanttargetinspace.Becauseofhisinterestinspaceresources,hedevisedamissionthatwouldflybyanasteroidandpossiblyorbitthe Moon. Stu and I discussed these possibilities, and it seemed that a fairlysignificant mission might be built around these small spacecraft. My colleagueEugene Shoemaker of the US Geological Survey was brought in early on theplanningofthismission.Genewasalegendinplanetarysciencecircles.AmemberoftheNationalAcademyofSciences,hehaddonetheoriginalgeologicalmappingof

the Moon before the Apollo program and was actively researching asteroids. Hisinterestand involvementwiththemissionbroughtbothprestigeandcredibility totheidea.

AnagreementbetweenNASAand theStrategicDefense InitiativeOrganization(SDIO) specified that NASA would provide the science team and thecommunications tracking support for the flight, and that SDIOwouldprovide thesensors,spacecraft,andlaunch.ThesensorshadbeendevelopedatLivermoreaspartoftheBPprogram,whiletheNavalResearchLaboratory(NRL)woulddesignandbuild the spacecraft, later namedClementine. Launchwas on a surplus Air ForceTitan II rocket, the same vehicle NASA used to launch the two-man Geminimissionsinthe1960s.BecausetheTitanIIpadattheCapehadbeendismantled,themission would be launched from Vandenberg Air Force Base near Lompoc,California.

The mission would put Clementine in a polar orbit around the Moon for twomonths,providingglobalcoverage.Thespacecraftwouldmapthecolorofthelunarsurface inelevenwavelengths intheultraviolet,visible,andnear-infraredportionsof the spectrum andmeasure theMoon’s shape from laser ranging. Other remotemeasurements would be acquired as opportunity presented. After this phase,Clementinewastoleavelunarorbitandflybythenear-EarthasteroidGeographos.ProgramManagerPedroRustan,anAirForcecolonel,wasaskilled,toughengineerwho kept us to deadlines. Stu became his deputy, coordinating many differentactivities,rangingfromscienceobjectivestospacecraftfabricationandtesting.TheScience Team, twelve lunar scientists with varied expertise, was selected fromindividual proposals submitted to NASA. Gene Shoemaker was named the teamleader,andIwashisdeputy.Together,weplannedmissionoperationswiththeNRLandLivermoreteams.TheScienceTeamcarefullyselectedthefilterbandpassesfortheimagingsystemsthatwouldallowtheidentificationoflunarrocktypesfromthecolorimages.

TheClementinemissionwasremarkableforitsshortdevelopmentcycleandcost.Twenty-two months elapsed from project start to launch, while a typical NASAplanetary mission took from three to four years. In FY 1992 dollars, NRL spentabout$60millionforthespacecraftandthemissioncontrolcenter.Livermorespentabout$40milliononsupportservicesandontheproductionofthemissionsensors.TheTitanIIlaunchvehicleandservices,suppliedbytheAirForce,werevaluedatabout$20million,withanadditional$10millionor so foravionicsupgrades.TheNASAScienceTeamcostacoupleofmilliondollars,andtheDeepSpaceNetworksupport was a few million more. By totaling those numbers, I estimate that the

missioncostabout$140million,or$540million in today’sdollars; forcomparison,thethen-recentlylostNASAJPLMarsObservermissioncostabitover$800million,ormorethan$2billionin2014dollars.

Those costnumbers causedconsiderable controversy,with some in the scientificcommunitywhiningthatthemassive“StarWars”(SDI)programabsorbedandhidmuchofClementine’scost.Infact,thewholepointoftheBrilliantPebblesprogramwastoadaptcheap,ruggedtacticalsensorstodeepspaceuseandthustakeadvantageofthecostsavingsprovidedbymassproduction(asopposedtothecustombuildsofmost space systems). Moreover, there was nothing to stop NASA from using thissame technology, other than a not-invented-here mindset and the still-prevalenttendencyinthespacesciencecommunitytogold-platescientificpayloads.

TheClementinemissiondemonstrated thevalueof the so-calledFaster–Better–Cheaper (FBC) paradigm.27The concept is not that cheapmissions are inherently“better”butthatbycarefullyrestrictingmissionobjectivestoonlythemostessentialinformation, it is possible to fly smaller capablemissions that can return 80 to 90percent of themost critical data; resources are often squandered in an attempt toachievethatlast10percentofperformance.MaybeFBCshouldberenamedFaster–Cheaper–GoodEnough.The broad success ofNASA’sDiscovery programover thelast twenty years, inwhichmission objectives are carefully defined and limited tocontroloverallcost,istestamentenoughtothegeneralvalidityoftheFBCconcept.Inadditiontoitsscientificreturn,theClementinemissionflight-testedandqualifiedtwenty-twonewspacecrafttechnologies,includingsolid-statedatarecorders,nickel-hydrogenbatteries,lightweightcomponents,andlow-mass,low-shock,nonexplosiverelease devices. All of these technologies have been employed on dozens ofsubsequent spacemissions,makingmanyof these spacecraft lighter,more reliable,andlonger-lived.

On themorningof January25, 1994, less than twoyears afterproject start, themembers of Clementine’s science team stood together on a cold,windyCaliforniabeachjustacoupleofmilesfromSLC-4W.WewatchedastheClementineTitanIIroseabovethe launchpadonacloudoforangesmokeandflame,arching intotheclear, blue Pacific sky. We followed the vehicle’s progress all the way throughstagingbeforelosingsightofit.IleftVandenbergexcitedaboutthemissionahead,butmymoodquicklychangedwhenScienceOperationsManagerTrevorSorensensentnewsthatwewereindangeroflosingthespacecraft(erroneouscommandshadbeen sent to Clementine, and the spacecraft was out of control). Fortunately, werecovered.

Once our spacecraft had safely inserted itself into orbit around the Moon and

began mapping its surface, we were eager to get our first images. Our perch forreceiving thismissiondatawasa convertedNationalGuardarmory inAlexandria,Virginia.Dubbed theBatcave, the armory served asmission control center for thedurationofthemission.Designedtosavefuel,Clementinehadtakenamonth-long,leisurely looping trip to theMoon, arriving there on February 19.When the firstimagefinallyflashedonthescreen,Iimmediatelyrecognizedthecraterbutduetoall theexcitement, initiallydrewablankon itsname.Quicklyconsulting thewallmap,IsawthatwewerelookingatNansen,acraterlocatednearthenorthpole.Avery strong sense of physically being present at the Moon came over me—I wasflyingacrossalandscapeasfamiliartomeasanyonethatIknewontheEarth.

Mission operations became a regular series of work cycles arranged around theroutine of collecting and downlinking data, verifying that the datawas good, andmakingsomeinitialscientificobservations,althoughacoupleofincidentsfrommytimeintheBatcavestandout.

AsClementine’sorbitwasabouttopassoverTycho,thelargestrayedcrateronthenear side of the Moon, I alerted everyone in the Batcave’s control room thatsomething incredible was about to appear. Audible gasps greeted the spectacularimages of the floor and central peak of Tycho that came into view. On anotheroccasion,Dave Smith, a science teammember fromNASA–Goddard Space FlightCenter,askedhowmuchpolarflatteningmightbeexpectedfortheMoon.Ireplied“almostnone,”mainlybecauseoftheslowrotationrateoftheMoon(onceevery708hours) combined with the rigid, nonplastic state of the lunar globe. Then, as theorbitalgroundtracksslowlymarchedwestwardacrossthefarsideoftheMoon,wesaw an astonishing falling off of topography toward the south pole. This largenegative relief was the rim and floor of the South Pole–Aitken (SPA) basin, animpactcratermorethan2,600kilometersacrossandmorethan12kilometersdeep.Geologistshadlongknownthatthisbasinwaspresent,butuntilClementinemappeditstopography,noonehadfullyappreciateditshugesizeandstateofpreservation.

Bynow,ClementinehadalreadyshownusthenatureofthepolarregionsoftheMoon, including peaks of near permanent sun-illumination and crater interiors inpermanent darkness. From his first look at the poles, Gene Shoemaker had aninkling that something interesting was going on. Gene tried to convinceme thatwatericemightbepresentthere,anideaaboutwhichIhadalwaysbeenskeptical.Atthattime,notraceofhydrationhadeverbeenfoundinlunarminerals,andtheprevailing wisdom was that the Moon had always been bone-dry. With Genearguing for us to keep an openmind andDeputy ProgramManager Stu Nozettedevisingabistaticradiofrequency(RF)experimenttousethespacecrafttransmitter

to “peek” into the dark areas of the poles, we moved ahead on planning ourobservations. This turned out to be the setup for a history-making eventmidwaythroughtheorbitalmappingcampaign.

AlthoughClementinedidnotcarrysensorsforthedetectionofwater,Stubelievedwecould improviseanexperimentusingthespacecraft’sradiotransmitter to“lookinto” the dark (and thus very cold) areas near the poles, places where water icemight exist. Radio echoes from the Moon could be detected on the giant radioantennadishatGoldstoneinCalifornia’sMojaveDesert.WithcarefulplanningandcommandingofthespacecraftbyRadioEngineerChrisLichtenberg,wesuccessfullytook bistatic radio frequency (RF) data of both poles during those phasing orbits,whenClementineshiftedtheperilune(lowpoint)ofitspolarorbitfrom30°southto30°northlatitude.

Tomy astonishment, a single pass over the dark areas of the south pole of theMoon showed evidence for enhanced circular polarization ratio (CPR), a possibleindicatorofthepresenceofice.Acontrolorbitoveranearbysunlitareashowednosuchevidence.However,CPR isnotauniquedeterminant for ice, as rocky, roughsurfaces and ice deposits both show high CPR. It took a couple of years for us toreduceandfullyunderstandthedata,but thebistaticexperimentwas successful—and a huge scientific bonus. In part, our ice interpretation was supported by thethen-recentdiscoveryofwatericeatthepolesofMercury(aplanetverysimilartothe Moon with a comparable polar environment).28 Our published results in aDecember 1996 issue of Science magazine set off a media frenzy, followed by adecadeofscientificargumentandcounterargumentabouttheinterpretationofradardataforthelunarpoles—anargumentthatcontinuestoalesserdegreetothisday,despite subsequent confirmation of lunar polarwater from several other detectiontechniques.29

TheBatcaveplayedhost toseveraldistinguishedvisitorsduringthetwomonthsthatClementineorbitedtheMoon,mostnotablyastronautsJohnYoung,afamiliarface tomembers of theSynthesisGroupandalways a friendof lunar science, andWubbo Ockels, a Dutch physicist with the European Space Agency. Ockels,encouragedbyClementine’s success, campaigned togenerateenthusiasmfor small,cheaplunarmissionsatESTEC,theEuropeanspacecenterintheNetherlandswhereheworked.USRepresentativesBobZimmerand JimMoranwere impressedwithour operation and pledged their support in Congress for future space efforts likeClementine. Finally, then-new Administrator of NASA Dan Goldin visited,distributing lapel pins and offering encouragement to theworker bees. Not all atNASAwereenamoredwiththemissionthough,withsomeresentingtheattentionit

had drawn, particularlywith regard to the inevitable comparisonswith their ownongoingandbudgetoverrunningroboticmissions.

WithClementine,wehadsuccessfullyreturnedtotheMoon,mappeditglobally,and made several significant discoveries. A Science Team press conference wasscheduledatNASAHeadquarterstoreportonthenewscientificfindings,butNASAintervenedatthelastminuteandcancelledourbriefing.Severalmutuallyexclusiveexcusesweregivenforthiscancellation,butitwascleartomembersofthescienceteamthat some in theagencywanted tokeepa lidon the scientific successof themission,whichwasembarrassing toNASAbecauseClementinewasmuchcheaperthansimilaragencyefforts,yetjustasscientificallyproductive,ifnotmoreso.Butintime, news of the discovery of “themost valuable piece of real estate in the solarsystem”was revealed.With urging from the planetary science community,NASAagreedtofundaresearchprogramtotakeadvantageoftheabundantnewlunardataacquiredbyClementine.

TwocamerasonClementinewithelevenfilterscoveredthespectralrangeof415to 1900 nm, where absorption bands of the major lunar rock-forming minerals(plagioclase,pyroxeneandolivine)arefound.Varyingproportionsofthesemineralsmakeupthesuiteoflunarrocks.Globalcolormapsmadefromthesespectralimagesshow the distribution of rock types on theMoon. The uppermost lunar crust is amixed zone, whose composition varies widely with location. Below this zone is alayerofnearlypureanorthosite,arocktypemadeupsolelyofplagioclasefeldspar—the original lunar crust, formed during the global “magma ocean”melting event.Craters and large basins act as natural “drill holes” in the crust, exposing deeperlevelsoftheMoon.Thedeepestpartsoftheinterior(andpossiblytheuppermantle)are exposed at the surface within the floor of the enormous (2,600 km diameter)SouthPole–AitkenbasinonthefarsideoftheMoon.

Before Clementine, good topographicmaps existed only for the near-equatorialareasundergroundtracksoftheorbitalApollospacecraft.FromClementine’s laserrangingdata,weobtainedourfirstglobaltopographicmapoftheMoon.ItrevealedthevastextentandsuperbpreservationstateoftheSPAbasinandconfirmedmanylarge-scalefeatures,mappedorinferred,fromonlyafewcluesprovidedbyisolatedlandforms. Correlated with gravity information derived from radio tracking, weproducedamapofcrustalthickness,therebyshowingthatthelunarcrustthinsoutunderthefloorsofthelargestimpactbasins.

As a result of this mapping, scientists could place the results of studies of theApollo samples into a regional, and ultimately, a global context. Clementinecollected special data products, including broadband thermal, high resolution and

star tracker images for a variety of special studies. In 1996, after our paper waspublished inScience, apress conferencewasheldat thePentagon toannounce theresultsofthebistaticexperiment:thediscoveryoficeatthesouthpoleoftheMoon.Inadditiontodiscoveringnewknowledgeoflunarprocessesandhistory,thismissionledastrongwaveofrenewedinterest intheprocessesandhistoryoftheMoon,aninterestthatspurredacommitmenttoreturntherewithbothmachinesandpeople.By peeking into the Moon’s dark polar areas, we now stood on the edge of arevolutioninlunarscience.

ThisrenewedinterestintheMoonledtotheselectionofLunarProspector(LP)asthefirstofNASA’snew,low-costDiscoveryseriesofplanetaryprobes.Thismissionfound enhanced concentrations of hydrogen at both poles, again suggesting thatwatericewasprobablypresentthere.Buttressedbythisnewinformation,theMoononceagainbecameanattractivedestination for roboticandhumanmissions.Withdirect evidence for significant amounts of hydrogen (regardless of form) on thesurface, there now was a known resource that would support long-term humanpresence. Lunar Prospector’s hydrogen discovery was complemented by theidentificationinClementineimagesofseveralareasnearthepolethatremainsunlitfor substantial fractions of the year—not quite the “peaks of eternal light”anticipatedbytheastronomersBeerandMädlerin1837,butsomethingveryclosetoit.30 The availability of material and energy resources, the two most pressingnecessitiesforpermanenthumanpresenceontheMoon,wasconfirmedinonepass.These two missions certified the possibility of using lunar resources to provisionourselvesinspace,thuspermanentlyestablishingtheMoonasanenablingassetforcontinuedhumanspaceflight.AremainingtaskwastoverifyandextendtheradarresultsfromClementineandtomaptheicedepositsofthepoles.

Missions flown over the last twenty years show how significantly Clementine’sprogrammatic template has influenced spaceflight. The Europeans flew theSMART-1 spacecraft to theMoon in 2002, largely as a technology demonstrationmissionwithgoalsverysimilartothoseofClementine.NASAdirectedtheAppliedPhysics Laboratory (APL) to fly the Near-Earth Asteroid Rendezvous (NEAR)spacecrafttotheasteroidErosin1995asaDiscoverymission,toattaintheasteroidexplorationopportunitymissedwhencontrolof theClementinespacecraftwas lostafter leaving theMoon; themissionwas renamedNEAR-Shoemaker afterGene’stragicdeathinanautomobileaccidentinAustralia in1997.India’sChandrayaan-1hada size andpayload scope similar toClementine.The selectionof theLCROSSimpactorasalow-cost,fast-tracked,limitedobjectivesmissionfurtherextendeduseoftheClementineparadigm.

The Faster-Better-Cheaper mission model, once panned by some in thespaceflightcommunity,isnowrecognizedasavalidmodeofoperations,absenttheemotional baggage of that name.31 A limited-objectivesmission that flies ismoredesirablethanagold-platedonethatsitsforeveronthedrawingboard.Whilesomemissionsdorequiresignificantlevelsoffiscalandtechnicalresourcestoattaintheirobjectives, an important lesson of Clementine is that for most scientific andexplorationgoals,“better” is theenemyof“goodenough.”Spacemissions requiresmart, leanmanagement; they shouldnotbe charge codes for feeding thebeast oforganizational overhead. Clementine was lean and fast; perhaps we would havemade fewermistakeshad thepacebeenabit slower,butdespite its shortcomings,themission gaveus a large, high-quality dataset, one still used extensively to thisday. In recognition of its substantial accomplishments, the Naval ResearchLaboratory transferred the Clementine engineering model to the Smithsonian in2002,whereitwasputondisplayintheNationalAirandSpaceMuseum,suspendedabovethedisplayoftheApolloLunarModule.

ItisprobablynottoomuchofanexaggerationtosaythatClementinechangedthedirectionoftheAmericanspaceprogram.AfterthefailureofSEIin1990–92,NASAwas leftwithno long-termstrategicdirection.For the first time in itshistory (butalas, not the last), the agency had no follow-on program to the shuttle/station,despiteattemptsbyDanGoldinandotherstosecureapprovalforahumanmissionto Mars, an insurmountable challenge both technically and financially. Thisprogrammatic stasiscontinueduntil2003,whenthetragic lossof thespaceshuttleColumbia led to a top-down review of US space goals. Because Clementine haddocumentedthestrategicvalueoftheMoon,thelunarsurfaceonceagainbecameanattractive destination for future robotic andhumanmissions.The resultingVisionfor Space Exploration (VSE) in 2004 made the Moon the centerpiece of a newAmericaneffortbeyondlowEarthorbit.ThoughMarswasdeclaredasaneventual(not ultimate) space objective, specific activities to be done on the Moon weredetailed in theVSE,particularlywith regard to theuseof itsmaterial andenergyresourcestobuildasustainableprogram.Regrettably,asIwilldetail,variousfactorscombinedtosubverttheVision,therebyendinganystrategicdirectionforAmerica’scivilspaceprogram.

Clementinewas awatershed, a hinge point that forever changed the nature ofspacepolicydebates.Wenow recognize a fundamentallydifferentway forward inspace—oneofextensibility,sustainability,andpermanence.Onceanoutlandishideafoundinsciencefiction,wenowknowthatlunarresourcescanbeusedtocreatenewcapabilities in space, a welcome genie that cannot be put back in the bottle.

Americansneedtoaskwhytheirnationalspaceprogramwasdivertedfromsuchasustainable path. We cannot afford to remain behind while others plan and flymissionstounderstandandexploittheMoon’sresources.Ourpathforwardintotheuniverseisclear.Inordertoremainaworldleaderinspace,andaparticipantinandbeneficiaryofanewcislunareconomy,theUnitedStatesmustagaindirectitssightsandenergiestowardtheMoon.

W

4AnotherRunattheMoon

ith the completion of the successful Department of Defense Clementinemission, the Moon was again viewed as a destination of value. Both

LawrenceLivermoreandtheNavalResearchLaboratorypreparedforaClementineIIasteroidflybymission,theunmetobjectiveofthefirstmissionduetoatechnicalfailurewithClementine’s thrusters after itdeparted theMoon.Someon the studyteamproposedamissionprofilethatwouldmirrortheplanofthefirstClementine,anasteroid flyby followedby insertion into lunarorbit.Theobjectivewouldbe tomap theMoonat greater resolutionwith additional instruments and followuponthediscoveriesmadebythefirstClementine.Thisrenewedlunarattentionwasnotwithout detractors, who questioned what Clementine had found. Congressappropriated funds for themission in 1997, but plans to fly itwere scuttledwhenPresidentBillClintonusedhisnewlyacquired line-itemveto tozeroout funds forClementine II. The Supreme Court subsequently declared the line-item vetounconstitutional,buttoolatetosavetheClementineIImission.

Around this time, NASA called for proposals to the Discovery program, a newseriesofsmallplanetarymissions,cost-cappedat$150million.1Thismissionserieswas NASA’s attempt to emulate the Faster–Cheaper–Better paradigm thatClementineencapsulated.ThenewNASAadministratorDanGoldinwasrenownedfor his advocacy of the FBC mode of business. The Discovery program receiveddozens of mission proposals. A single planetary scientist, called the principalinvestigator (PI), ledeachproposal. In1995,NASApickedLunarProspector (LP),ledbyAlanBinder, as the firstDiscoverymission, deeming it the least expensive,leastriskymissionproposalithadreceived,requiringonlyasmalloperationsteam.ItsselectionalsoavoidedhavingtheClementineteamagainsetfootonwhatNASAthought to be its turf, since a second NRL Clementinemultiple asteroid flyby ofcomparablecostwasalsoproposed.

The particle and geochemical sensors of LP perfectly complemented themultispectral images and laser altimetry data obtained byClementine. Combined,these two missions gave us our first global look at lunar mineral and chemicalcompositions, surface topography and gravity, and regional geology and producedthedatasetsofthenever-flownLunarPolarOrbiter,themissionscientistshadlong

desired.Forexample,wefoundthathighconcentrationsofradioactiveelementsinthe lunar crust are localized in the Procellarum topographic depression of thewestern near side, an unusual global asymmetry that is still unexplained. Moreimportantly, LP’s neutron spectrometer found high concentrations of hydrogen atbothpoles inroughlyequalquantities.Theneutronexperimentonlymeasures theconcentration of elemental hydrogen, not its physical state—that is, whether it ispresent intheformofwater iceorexcesssolarwindgas inthecoolpolarregolith.From this information, aswell the results on lunar polar lighting and the bistaticradar from Clementine, the evidence continued to mount that something veryinterestingwaspresentatbothpolesoftheMoon.2

The Moon’s spin axis is inclined 1.5° from the normal to the ecliptic plane, anearly perpendicular orientation; thismeans that the Sun always hovers near thehorizon at the poles of theMoon. The apparent angular width of the Sun at theEarth-Moondistanceisabout0.5°ofarc,sosometimestheSuncouldbeabovethehorizonandat other times, below it.Butbecause theMoon’s surface is roughandirregular,withlargecratersandbasins,thereareareasnearthepolesthatintheorycouldseeeitherpermanentsunlightorpermanentdarkness.Clementinespentonlyseventy-one days in lunar orbit during the southernwinter solstice, so it providedilluminationdataforonlypartofthelunaryear.Nonetheless,analysisshowedthatsmallareasnearthecraterShackleton,locatednearthesouthpoleoftheMoon,weresunlitmorethan70percentofthesouthernwinterday.Threeareasnearthenorthpole were illuminated 100 percent of the day (northern summer). Data for theoppositeseasonswerenotobtained.

An intense scientificdebateover theexistenceof ice at the lunarpoles spannedmost of the decade around the turn of themillennium.The lunar ice controversystemmedfromtheambiguityofradarCPRasanindicatorofbothsurfacephysicalproperties and composition. Because the datawere nondeterminative, they provedfertile ground for intense argument.Apaper presented at the 1995Lunar ScienceConferenceinHoustondescribedtheresultsofhighresolutionimagingofthelunarsouthpolebythelargedishantennaatArecibo,PuertoRico.Theseimageswereableto peek into the totally sunless areas near the pole. Interestingly, small regions ofhigh diffuse backscatter were seen.3 This high diffuse backscatter, called circularpolarizationratio,orCPR,isconsistentwithasurfacecomposedofwaterice,ahighconcentration of angular blocks, or both. Based on our result from the bistaticexperiment, the Clementine team preferred the water ice interpretation, whileothers in theradarplanetarysciencecommunityarguedforanoriginfromsurfaceroughness.

ThenewLPneutrondataclearlyshowedanexcessofhydrogenatthepoles,butthesurfaceresolutionofitshydrogenconcentrationmapswasverylowandwecouldnot be certain whether the signal was caused by a large area of relatively lowconcentration—that is, solar wind gases implanted in the regolith—or by small,isolatedzonesofveryhighconcentrationsuchasiceinpermanentlydarkareas.Thiscontroversyragedonaswetriedtodesign,build,andflya small imagingradar totheMoontofollowupontheClementineandLPdiscoveries.Despiteproposalsforsmall NASA robotic missions, European Space Agency interest, and even someproposed commercial missions, no flight opportunities were to arise until late in2003.

Thegreatestremainingunknownswereaboutthepoles,thoseareaswherewehadfound permanent darkness, possible permanent sunlight, and enhancement ofhydrogen concentration, possibly indicating the presence of water ice in the darkregions. All of these new insights showed that the Moon was more complex andinterestingthanwehadthought.Akeydiscoverywasthezonesofextendedsunlight.Findingareasonthesurfacethatreceiveilluminationforalmostallofthelunardayremovedoneof thebiggesthurdles tohumanhabitationof theMoon: theneed toprovideapower source for electricityandheatduring the fourteen-daynighttime.Nuclear power is best suited to the task, but the high costs of such power, bothtechnicalandsocietal,madelunarreturnunaffordable.

Incontrast,thediscoveryofareaswherepowercouldbegeneratedconstantlybysolararraysnowmadeextendedstaysontheMoonbypeoplefeasible.Inaddition,illuminated terrain—evenby sunlight at grazing incidence—makes the extremelycoldlunarnighttolerable.Areasofconstantsunlightneardepositsofwatericecreate“oases”nearthepolesoftheMoonwherehumanhabitationispossibleandperhapsevenprofitable.

TherewasaninterestingcodatotheLunarProspectormission.Afterloweringitsorbit to about 20 kilometers, as close as it is possible to orbit the Moon withoutrunning into someof itshighermountaintops,andcollecting somehigh-resolutiondatafromthiscloseorbit,thespacecraftwasdeliberatelycrashedintoacraternearthesouthpoleonJuly31,1999.TheobjectiveofthiseffortwastokickupmaterialfromtheimpacttotrytodetectthepolarwaterintheejectacloudwithtelescopesonEarth.Unfortunately,noejectawereobserved,sothedebateoverlunarpolarwatercontinued.(ThesameexperimentwasrepeatedtenyearslaterduringtheLCROSSmission, with more productive results.) The LP spacecraft did carry an unusualcargo,however: someofGeneShoemaker’s ashes.4Theurn and theLP spacecraftnowrest in the floorofa craternear the southpole, subsequentlygiven thename

Shoemaker, a fitting tribute to Gene and his contributions to the study andexplorationoftheMoon.

WebelievedthatwehadfoundwateratthepolesoftheMoon.Nowweneededacommitmenttogobacktoverifythenewfindings.

MarsManiaRobotic missions to Mars have dominated the last twenty years of planetaryexploration,anemphasisstemminginpartfromtheplanetarysciencecommunity’sefforts to fly a series of roboticmissions thatwill eventually lead to the return ofsamples from Mars to Earth, an ambitious and very expensive proposition. WithNASA’sroboticspaceflightprogramstillunderintensescrutinyafterthefailuresoftheinitialHubbleSpaceTelescopemissionandJPL’s1993MarsObserverspacecraft,AdministratorDanGoldin,aboosterofbothhumanMarsmissionsand the searchfor life,wasunable toconvince theClintonadministrationorCongress toponyupenoughmoneytofundanambitiousMarssamplereturneffort.5Undeterred,Goldinapplied the FBC paradigm to Mars missions and moved forward with the MarsPathfinder mission, a small rover called Sojourner that landed on Mars using aparachute and airbags deployed for final impact. Sojourner took some images andmadearudimentarychemicalanalysisof thesoil.Pathfinder,althoughtechnicallysuccessful, did not fundamentally advance our knowledge and understanding ofMarsanditssurfaceprocessesandhistory,thusmissingoutonthe“better”—oreventhe“goodenough”—partofFBC.

Anevent thatwouldconcentrateeveryone’sattentiononMarsduring the1990sturned out not to be from any spacemission but from a laboratory right here onEarth.Wehadknownforsometimethatararegroupofmeteorites,theShergottite-Nahklaite-Chassignitegroup(SNC),hadunusualchemicalpropertiesandrelativelyyoung ages of crystallization. Analysis of these rocks found trapped argon withinthemidentical incompositiontoanalysisof themartianatmospheremadein1976bytheVikingspacecraft.Scientistsconcludedthatthesemeteoritesarepiecesofthemartiancrust, thrownintospacebyanimpactonMarsthateventuallymadetheirway to Earth. The composition of these meteorites seemed to fit what we hadinferred from Viking and remote sensing about the composition of Mars. Thesemeteoriteshadagesmuchyoungerthanmostmeteorites,nearlyallofwhichformed4.6 billion years ago, and lunar samples three to four billion years old, againcongruent with our understanding of the extended geological evolution of themartiansurface;craterdensitydatasuggestedthatagesofgeologicalunitsonMars

spannedanestimatedrangefromfourbilliontolessthanonebillionyearsold.Onerather unusual martian meteorite, ALH 84001, was found in Antarctica anddetermined to be relatively old: 4.5 billion years. Using a scanning electronmicroscope, tiny lifelike shapes were found inside the martian meteorite, formsresemblingcertaintypesofterrestrialbacteria,thoughmuchsmalleranduniqueindetail.Theauthorsof theALH84001 study suggested that theseobjectsmightbefossilsofbacteriafromanearlyepochofMarshistory.Inotherwords,theyassertedthat traces of former extraterrestrial life had been discovered, a sensational claimthatgrabbedandheldheadlines.6

A flood of media coverage followed, eventually leading to press conferences atNASAHeadquarters and finally, aPresidentialRoseGarden statement.With thatexplosion of publicity, Dan Goldin moved to leverage some high-level politicalbacking for a permanent, sustained Mars exploration program.7 Although humanmissionstoMarsremainedbeyondthereachoftechnology,aseriesofroboticprobesleadinguptothatelusivesamplereturnmissionwouldkeeptheMarsscientistsandNASA’sJetPropulsionLaboratorybusy.“TheQuestforLife”scientificgravytrainwasborn.

BySaganizingthenation’scivilspaceprogram—thatis,byenshriningtheQuestforLifeasNASA’sprincipal rationale for spaceexploration—DanGoldin took themartianaspectofthisnewrationaleandencapsulateditintotheslogan,“FollowtheWater.”The idea behind thismessagingwas that life aswe know it requires thepresence of liquid water.8 This dictum was followed by conducting a series ofmissionstoareasonMarswhereitwassuspectedthatflowingwaterhadoccurredinthe past. A cynical observermight notice that aside from the potential finding ofextantorfossilmartianlife,nocriteriaforaprogrammaticexitfromthisexploratorypathweredefined.Inessence, thenewseriesofMarsmissions tookona lifeof itsown, becoming a permanent scientific and engineering entitlement program—aconstant, uninterruptible cadence, elevated beyond the realm of peer-reviewselection pressure or second thoughts from planetary scientists, a situation viewedwithdismaybythelunarcommunity.

Despite the positive indications acquired from theClementine andLPmissionsand subsequent studies of the presence of water ice and near-permanent sunlightnear the poles of the Moon, NASA had no interest in conducting any follow-upinvestigations.Although thesediscoverieswouldpermit longduration stayson theMoonandpossibleresourcesforadditionalspaceflightoptions,thelunarcommunitycouldnotgetthefundingtoevenstudynewmissionsthatwouldhavecostasmallfractionoftheJPLMarsprogrambudget.Clearly,apolicydecisionhadbeenmade

at some level that no large-scale human exploration program beyond LEO waspossible: NASA’s robotic exploration budget was to be sequestered over the nextcoupleofdecadesforvariousMarsmissions.Thispolicywasneverformallywrittendown,butastheysay,moneytalks.PredominantineverysubmittedNASAbudgetforroboticscienceduringtheClintonyearswere“green”spacecraftforMissionstoPlanetEarthandMarsorbitersandrovers.TheformerwerethepetprojectofVicePresidentAlGore,whilethelatterwastheimplementationofthewishlistsofDanGoldin,CarlSagan,theJetPropulsionLaboratory,andlikemindedmembersoftheSagan-foundedPlanetarySociety.

However, the Mars exploration program started running into some serioustechnical problems. After the renowned Pathfinder mission in 1997, the firstsuccessful mission to Mars since Viking two decades before, the next two Marsmissionsfailed.TheMarsClimateOrbiter,a1999missiondesignedtocharacterizeatmosphericphenomenaandlookforpossiblecluestotherecordandmechanismsofclimatechangeontheplanet,misseditsorbitalinsertionandwaslost.Post-missionanalysistracedthisfailuretotheuseofEnglishunitsofmeasurementinacommandstream that required metric units. Appropriate derision of JPL and agencycompetence followed this jaw-dropping revelation. Next, the Mars Polar Landerstopped transmitting shortly before its entry into the martian atmosphere; theinferenceisthatithadcrashedonthemartiansurface.Serioussoul-searchingattheagency followed these failures,butonlyabout themeans,notabout theends.Onegreat concern was with Goldin’s alleged devotion to FBC (although it is hard toascribebothof these lostmissions to thisparadigm, since their combined costwasover$300millioninFY1999dollars)andnotwiththeideaofacontinuingseriesofMarsmissionsdesignedtofollowthewater.Followingthesefailures,therevampingof the program now assured that the means of future missions to the red planetwouldeachcostanappropriatelystaggeringamountofmoney,allinpursuitoftheelusiveends:waterandthereforepossiblypastlife.

TheHumanSpaceProgramHuman spaceflightefforts following thedemiseofPresidentGeorgeH.W.Bush’sSpace Exploration Initiative (SEI) in 1992 included the continuation of the spaceshuttle program, with its wide variety of satellite deliveries and life scienceexperiments,aswellasservicingmissionstotheHubbleSpaceTelescope.Thegoalofbuildingapermanentlyoccupiedhumanspace stationhadnotbeenabandoned,but ithadbeenreimagined.SpacestationFreedom, initiallyproposedbyPresident

RonaldReaganin1984,wentthroughseveraldesigniterations,changesthatdelayedthestartofitsconstructionandincreasedthecostoftheprogram.Despiteprogramreview after the Challenger accident and the grounding of the shuttle fleet byhydrogen leaks, NASA pressed on with station design and redesign. The fits andstartsoftheprogramledtoexasperationinCongress,whereitsurviveda1993voteintheHouseofRepresentativesbyamarginofone.Thehumanspaceflightprogramhadreachedacrisisofbothconfidenceandcapability.

DespitethedeclineandterminationoftheSEI,debatecontinuedoverthefuturedirectionofhumanspaceflight,asoutlinedbythePaine,Ride,andAugustine1990reports.Atthistime,oneofthebiggestconcernsofscienceandtechnologypolicywasthe problem of nonproliferation. The Soviet Union had dissolved, and therewereconcernsintheWestthatRussianscientistsmightselltheirservicesandcapabilitiestoroguenationstomaketheinfamous“weaponsofmassdestruction”andcausethespread of nuclear capabilities. It was thought by some that a joint space projectinvolvingboththeUnitedStatesandRussiaincollaborationwouldkeeptheRussianmilitary industrial complex safely occupied and under the scrutiny of itsWesternpartnernations.TheSovietshadbuiltafairlylargeandcapablespacestationinthe1980s called Mir. Soviet cosmonauts conducted routine, extended stays on Mir,arriving and returning on their Soyuz spacecraft. Announced in 1993, the logical,initialstartingpointforthisnewEast-Westspiritofcooperation,calledShuttle-Mir,hadrotatingcrewstakingthespaceshuttletoMir,wherecrewswouldlivetogether,showingthatwecouldworktogetherpeacefullyinspace.9

Between 1995 and 1998, there were eleven shuttle missions to Mir, whereAmericanastronautsspentclosetoathousanddaysinorbitaboardtheRussianspacestation. Joint operational and flight techniques were developed between the twocountries. Despite some shaky moments (including a fire onboard the stationrequiring quick and decisive action by the crew), both parties considered thiscooperative flight experience successful, leading to the final redesign of the U.S.spacestationasanewInternationalSpaceStation(ISS).10Thisnewdesignwouldbebased on some key components provided byRussia.TheZarya (FunctionalCargoBlock),launchedin1998,andtheZvezdahabitatandlaboratory,launchedin2000,wouldbecomethenucleusofthenewmodularspacestation.Overthecourseofthenextdecade, twenty-sevenshuttle flightsand sixRussianProtonandSoyuz flightswould be needed to assemble the ISS in orbit. Starting in 2001, the ISS has beencontinuouslyoccupiedbycrew,includingduringtheperiodofthethirtymonthsthattheshuttlewasgroundedaftertheColumbiaaccidentof2003.Withthedeliveryandattachment of the AlphaMagnetic Spectrometer, assembly of the ISS was finally

completedinMay2011.In theearlyyearsof thenewmillennium,asassemblyof theISS finallybegan,

someintheagencyconsideredthepossiblenextstepsforhumansinspace.DespitethefailureoftheSEIandtheongoingdifficultiesoftheroboticMarsprogram,theobsessionwithhumanMarsmissionswasfirmlyentrenchedwithinNASA.Mostoftheagency’sadvancedplanningpeoplespent their timedevisingnewarchitecturesdesignedtoachievethatelusivegoal.Acoregroupofengineers intheExplorationProgramOfficeattheJohnsonSpaceCentercontinuedtoevaluatetherequirementsanddifficultiesofahumanMarsmission,aswellasalternativeconcepts involvingreturntotheMoon.Thepost-SEIanalysisoftheHoustonengineershaddeterminedthat with the launch of a few large expendable rockets and a couple of shuttleflights, we could return humans to the Moon.11 Their analysis showed that themassive infrastructure creation outlined in the 90-Day Study was not strictlynecessary, at least for the initial steps of human lunar return, especially if lunarresources (oxygen) were incorporated into the architecture. Such amission wouldhave limited stay time and capability, but at least it established a foothold on thelunar surface and could become a point from which the possibilities of extendedpresencecouldbeinvestigated.

Studies of these architectures and plans continued, including investigations ofmissions to destinations other than the Moon. An early study mission favorite ofNASAwas theLagrangian-point(L-point)mission,ahumanmissiontooneof thegravitationalbalancepointsintheEarth-Moonsystem,apointatwhichEarthandMoonappeartobestationaryinthesky.TheproblemwithL-pointmissionsisthatthere isnothing there, except forwhatweput there. In the future,L-points couldbecomecriticallyimportantasstagingareasformissionstotheplanets,ortocollectexportedmaterialsuchaswater launchedfromEarthorfromtheMoon.Althoughthere was some interest in human missions to near-Earth asteroids, they werethoughttobeofmuchlessimportance,somethingtobereconsideredinthefuture.Atthetime,littlewasknownaboutmostoftheseobjects,andasteroidshadmostofthedisadvantages of aMarsmission (months of travel time, poor abort capability,andsoon)withfewofthebenefits—forinstance,mostoftheseobjectsaresimple,relativelyhomogeneousrocks,offeringlittleinthewayofexploratoryvariety.

As study of human Mars mission architectures continued, two things becameincreasingly clear. First, several technical developments, some of significantmagnitude,wereneededbeforehumanmissionstotheplanetwerefeasible.Someoftheseinvolved“knownunknowns,”thingsweknowthatweneedbutdon’tyethave,like nuclear rocket propulsion or a solution to the dreaded entry, descent, and

landing (EDL) problem,12 while others consisted of the “unknown unknowns,”problemsofmissiondesignorrequirementsthatwedon’tevenknowabout,letalonehaveanyideahowtosolve.Giventhestateofourknowledge,thesestudiesshowedthat a humanMarsmission is not possible in the near future.Moreover, even atfavorable opportunities, a Mars mission requires between one and two millionpounds to low Earth orbit, most of which is propellant. It was estimated that toassemble inorbitaMars spacecraftable to conducta singlehumanmissionwouldrequirebetweeneightandtenlaunchesofaSaturnV-classheavyliftlaunchvehicle.TheentiremannedApollomissionseriesof1968–72launchedtenSaturnVrockets.ThismeansthatasinglehumanMarsmissionwouldcostseveraltensofbillionsofdollars,evenifsuchaheavyliftvehicleexisted.Other,moreinnovativeapproacheswouldhavetobeconsidered.

Akeysteptowardunderstandinghowtoconductahumaninterplanetarymissioncamein1990whenRobertZubrin,anengineerfromMartin-Marietta,publishedhisMarsDirect architecture.13Although thisplanbypassed theMoon, its significanceforlunarexplorationderivesfromitsrelianceoninsituresourceutilization(ISRU).By manufacturing propellant on Mars for Earth-return—processing the carbondioxide(CO2)inthemartianatmosphereintomethane(CH4)forpropellantforthereturn trip—significantmass savings are realized, thusgreatly reducing the initialmassrequiredinLEO.Inaddition,theMarsDirectarchitectureseparatedcargoandcrew.Anuclearpowerplantandtheprocessingequipmentneededtomakemethanepropellantfromtheatmospherewouldbedeliveredtothemartiansurfacetwoyearsbefore the crew arrived. This approach introduced a safety factor, in that, if theatmosphere processing was less efficacious than believed, the crew would not betrapped on the surface ofMarswithout the fuel to get home because theywouldlaunchfromEarthonlyafterthereturntripfuelhadalreadybeenmanufacturedandstoredonMars.Despitethesebenefits,engineersfrombothNASAandtheaerospaceindustrywereslowtoaccepteventheminimalriskintroducedbytheISRUschemeproposed by Mars Direct. This ingrained resistance to ISRU carried over toarchitecturesforlunarreturnaswell.

Despite the innovative nature of some ideas in Mars Direct, a human Marsmissionwasstilltoohighafiscalandprogrammaticclifftoscale.Thus,formostofthe1990s,despitethepresenceoftheallegedfossilformsinALH84001andGoldin’slobbying,theMarsprogramremainedaseriesofscientificroboticprobes“followingthewater”whileconsumingmoreandmoreoftheplanetaryexplorationbudget.

TheLossofShuttleColumbiaandItsAftermathIntheyearsafterLunarProspector,butbeforetheVisionforSpaceExploration(ca.1998–2004), several attempts were made to restart lunar exploration, at least intermsofaseriesofroboticflightstoaddresssomeofthenewandexcitingfindingsandunknownsaboutthepoles.Thevociferousdebateoverthepresenceandextentof polar ice continued and it was clear that more and higher quality data wereneeded to resolve the issue of water ice. Earth-based radio telescopes were barelyabletoseeintopartsofthepermanentlyshadowedpolarareasoftheMoon.Boththeeighty-meter Deep Space Network Goldstone and the huge, three-hundred-meterAreciboradiodishmappedthesouthpoleoftheMoon,lookingforevidenceforthepresenceofice.Thedatawereinconclusive,sincediffusebackscatterobtainedsolelyfromzerophase (monostatic) radar, inwhich the sameantenna sendsandreceivesthepulses,cannotuniquelydistinguishbetweenrockandice.Thebistatictechnique,wherethereceivingantennaisdifferentandseparatedbyaknowndistancefromthetransmitter,canuniquelydeterminethis,providingevidencethatcausednumerousscientiststosupporttheinterpretationthaticehadbeendetected.14Asabelieverinthepolar icehypothesis, I canattest toourdesire toobtainnew,highqualitydatafroman orbiting radar experiment.The problemwas finding a ride to theMoon.Japanhaslongharboredlunardreamsandhadpreparedamostambitiousorbitingmission,SELENE(laterrenamedKaguya),aspacecraftthesizeofaschoolbuswithapayloadofalmostevery remote sensing instrumentknown tous.15ButSELENEkeptgettingdelayed,thenwasgroundedbyalaunchvehiclefailureandaJapaneseeconomyinrecession.Europekeptstudyinglunarmissions, includingbothorbitersandasouthpolarlander,buteachtimesuchaflightwasproposed,itwasdeferred.After downsizing their lunar mission into a small, technology demonstration,Europe’sSMART-1orbiterfinallylaunchedinlate2003,takingoverayeartospiralouttotheMoonusingsolarelectricpropulsion.TheSMART-1missionhadlimitedinstrumentationbutitcontributedtoourknowledgeofthepolesbyimprovingourmappingcoverageandextendingobservationofpolarlightingoveralongerseason.

AprojectsponsoredbytheDefenseAdvancedResearchProjectsAgency(DARPA)in2003lookedatthepossibleimpactofusinglunarmaterialresourcestocreatenewcapabilities in space. This effort was mostly a paper study, although its authorshopedtoparlaythatreportintoaseriesofsmallroboticmissionsdesignedtofollowuponthepolardiscoveries.IwasworkingattheJohnsHopkinsUniversityAppliedPhysicsLaboratory(APL),auniversity-basedresearchorganizationsimilartoNASAJPL, when they studied that effort. We outlined concepts for a fleet of smallsatellites,each less than100kilograms, thatcouldbeoperated in tandemtocreate

high-resolution data on lunar polar environments and materials. Such a missionseries would yield definitive answers for some polar questions, allowing us tounderstandifdevelopinglunarwaterwasfeasibleandwhatleverageinspacefaringcapabilities it would yield. Although this topic is potentially the kind oftransforming,“farout”ideaDARPAclaimstoseek,thestudywasnotapprovedtothenextlevelofdevelopment,dashingthehopesoflunarenthusiastsyetagain.

Despite its deferment, several positive results came from this effort. Weunderstoodhowtoconfigureasmallmissionthatcouldgethighqualitydataforthepoles.Aparametricstudybyagroupat theColoradoSchoolofMines ledbyMikeDuke, former lunarsamplecuratorandoneof themastermindsof the1980s lunarbase movement, led us to understand the break points for lunar mining.16 Forexample, what concentration levels of water make the effort of lunar miningeconomicallyworthwhile?Itturnsoutthatwaterconcentrationsofatleast1weightpercent are needed to balance the estimated costs of extraction, including thetransportation system. Fortunately, we already knew that the existence of suchquantitieswas likely: LP hydrogen data indicated an average concentration of 1.5weightpercentfortheentirepolarregion,suggestingthepossibilityofevenlargeramountsofwaterintheshadowedareas.

OnFebruary1,2003,thespaceshuttleColumbiabrokeapartduringreentry.17Allsevencrewmemberswerekilled.Untilthecauseoftheaccidentcouldbedeterminedandafixapplied,theshuttlewouldremaingrounded.AswiththelossofChallenger,the previous shuttle disaster in 1986, this accident once again focused thenation’sattentiononthemeaningandpurposeofournationalhumanspaceflightprogram.Butthistime,itdidmorethanthat.SeanO’Keefe,thenewNASAadministratorwhohadsucceededDanGoldinin2001,hadareputationasa“green-eyeshade”guy.Hehad been recruited to solve the agency’s considerable budgetary and accountingproblems with the International Space Station project, which he did during histenureofoffice.Profoundlyshakenbytheshuttleaccident,O’Keefedecidedthatifhumansweregoingtocontinuetorisktheirlivesbygoingintospace,theremustbesome great andmeaningful purpose of national import to the trip.18 O’Keefewasdeterminedtofindit.

As most attention was directed to the Columbia accident investigation, asimultaneous and largely unnoticed parallel effort was undertaken to review thepurposeandobjectivesofhumanspaceflight.19Itwasrecognizedthatfuturebudgetsforthecivilspaceprogramwerelikelytobetightlyconstrained,soanypossibleplansmustbeconstructedforanausterefiscalenvironment.Giventheselimitations,wasthereawaytorevitalizethehumanspaceflightprogram,orhadwereachedtheend

ofthetrail?Among those considering the next steps during this interruption in the human

spaceflightprogramwasKlausHeiss,aneconomistwhohadconductedsomeoftheearly feasibility studies of the shuttle. He became convinced that a return to theMoonwiththeaimoflearninghowtoestablishpermanencethroughtheuseoflocalresourcescouldbeachievedundercurrentbudgets,layingthegroundworkforlater,moreambitiousspaceefforts.AfriendoftheBushfamily,Klauswentdirectlytoseethepresidentwithhisidea,whopasseditontoNASAfordetailedtechnicalstudy.AtHeadquarters, Associate Administrator for Human Spaceflight Bill Readdy andmembershisteamundertookafeasibilitystudyofHeiss’splanfortheestablishmentofabaseontheMoon.20ThegroupcontinuedtoworkontheproblemofareturntotheMoonforthenextyearandahalf,comingupwithanapproachthatwasbothaffordableandtechnicallyrobust.21This“GoldTeam”undertookanexaminationofthe problem of trans-LEO human spaceflight, independent of previous advancedstudywork.

Overtheremainderof2003,amajorcabinet-levelstudyofthehumanspaceflightprogramwascompleted.TheWhiteHouseOfficeofScienceandTechnologyPolicy(OSTP),Office ofManagement andBudget (OMB), theNationalSecurityCouncil(NSC) and NASA all participated in this top-level review. Presidential ScienceAdvisorJohnMarburgertookanunusualandimpressivelyindependentpath.Ratherthan rehashing the plans of previous “visionary” efforts and reports, he posed afundamental question about human spaceflight: Why? What is our long-rangepurposeinspace?

Manyhavewrestledwiththe“Why?”questionovertheyears.Typically,thissortofponderingbeginsandends inone’sownsubdisciplinewithinthespacebusiness.Formostofthescientificcommunity,theanswerhasbeentostudytheuniverse.Foraerospace industrialists, it is to get long-term government contracts to build thebiggest, most expensive machines ever imagined. For agency bureaucrats, it is tostart,expand,andmanagea largecontinuingprogram.Marburgerreexaminedtheissueandposedaquestion:Whynotbringspaceintooureconomicsphere?Foryearswehaveheardabout“limitsofgrowth”andvariousenvironmentalcrises,ironicallyenough,muchofthistalkspurredbythepicturesofEarthtakenfromtheMoonbytheApolloastronauts.But spacecontainsvirtuallyunlimitedquantitiesofmaterialandenergy,andthus,intheory,unlimitedwealth.Whynotfocusondevelopingthetechnologyneededtoharvestthatwealthforthebenefitofhumanity?

WhilethepublicfocusedontheColumbiaaccidentinvestigation,twocompetingstreams of thought emerged.22 One, favored by OSTP and OMB, focused on the

practical andeconomicaspects of the spaceprogram.Couldwe reorientand retooltheprogramtobecomeacreator,ratherthanaconsumer,ofwealth?Todothat,wewouldneedtolearnthetechniquesofplanetaryresourceutilization,habitation,andextendedoperations.DuringApollo,wehadvisitedtheMoonbrieflyforthepurposeof scientific study and exploration. To extract useful products from the materialsfound in space, we would need an extended presence and different types ofequipmentandoperations.Giventhenewfindingsaboutthenatureandpotentialofthe lunar poles, theMoon quickly emerged as the initial destination for the civilspaceprogrambeyondLEO.

Thesecondstreamofthoughtaboutfuturedirectionswasaveryfamiliaronetolongtimespaceobservers:ahumanmissiontoMars,theprojectthatmanyhadlongdreamed about. Once again, NASA hoped to emerge from the ashes ofColumbia,Phoenix-like, to takehumankind to theplanets. It is fair to say thatnotall at theagencywereonboardwiththisdirection—Readdy’sworkonthelunarbasestudies,forexample,showedconsiderablesupportforareturntotheMoon—butitisequallyfair to say that many were Mars-oriented, especially those involved in advancedplanningdecisions.Alookthroughallthedocumentstheagencyproducesdetailingfuturemissionsshowsthattheylargelyrevolvearoundthefuture,imaginedneedsofahumans-to-Marsprogram.Zubrin’sinfluencehadinfiltratedtheagencyenoughtoincorporatesomeofthefeaturesofhisMarsDirectarchitecture,includingideaslikesplittingcargoandcrewmissionsegmentsandISRUpropellantproduction.Butnomatterwhichwayitwascut,ahumanmissiontoMarswasstilltoobigastretch,amuchlargereffortprogrammatically,technically,andfiscallythanreturningtotheMoon.Thebattlelineswerebeingdrawn.

These behind-the-scenes events were largely unknown tome as 2003 wore on.ThenachancemeetingoccurredataNovembergatheringoflunarbaseadvocatesinHawaii.Atthatgathering,Idescribedresultsforthelightingconditionsatthelunarpoles and the evidence forwater in thedark areas.Also in attendancewas IndianscientistNarendraBhandari,whodescribedhiscountry’splanstoflyitsfirstmissiontotheMoon,theorbiterChandrayaan-1.Thissmallsatellitewasaboutthesamesizeand capability as Clementine, and I felt an immediate affinity for their effort.Duringabreak in themeeting, IapproachedBhandariandaskedhim if theyhadconsidered flying imaging radaraspartof thepayload tomap thedarkareasnearthe poles. He replied that they had considered one, but imaging radars were tooheavy and power-hungry and as such would not fit on a small spacecraft. I toldBhandari about our efforts tominiaturize a radar instrument for this purpose;webelievedthatwecouldmakeanimagingradarthatwouldbelessthan10kilograms

inmass andwould use only 100watts of power, an order ofmagnitude less thantypicalradarinstruments.HepromisedtoreportourdiscussiontotheIndianspaceagencyandgetbacktome.

As the yearwaned, excited rumors circulated throughout the space communitythatabigannouncementonspacepolicywasimminent.TheinitialrumorheldthatPresidentGeorgeW.BushwouldunveilanewmajorspaceinitiativeinDecember,onthehundredthanniversaryof theWrightBrothers’ first flightatKittyHawk.23But that anniversary and celebration came andwent without any announcement,causing some to believe that the policy plan was in trouble, when in fact it wasmerely in its final stages of review and briefing to Congressional and Executivepersonnel and staff. At a White House meeting in mid-December 2003, a finalreviewofthenewinitiativewasheld.Theideawastoannouncethepolicygoalandthen implement it, giving NASA a one-time budget augmentation of about $1billionspreadoverthecomingfiveyearswiththeagency’sbudgetrisingonlywithinflationinsubsequentyears.Becausetheshuttlewasanexpensive,labor-intensivevehicle, its operating costs constituted a large fraction of the total NASA budget.Results coming out of the Columbia Accident Investigation Board urged that theshuttleberetired.Thenewinitiativeslatedtheshuttleforretirement,tobereplacedbyanew,lessexpensivehumanspacevehicle,theCrewExplorationVehicleorCEV,with both form and specifications to be determined. This replacement spacecraftwould consume less of the annual agency budget, creating a “wedge” of moneysaved fromthe shuttleprogramthat couldbe spentonmissionsbeyond lowEarthorbit. Thus, from the very beginning of the new initiative, the agencywas beingchallengedtoapproachtheeffortinanewandinnovativeway.Thiswasnottobeatypicalnewprogram,withautomatic“plus-ups” to swell thebudget, somuchasanewstrategicdirection.Withinbroadboundaries, theagencywasgiven latitude topursueitsnewdestinationgoalsinthemannerthatitperceivedbest.Butgowhere?

During the final reviewmeeting, President Bushwas presentedwith summaryargumentsforprogramsthatfocusedonlunarreturnandhumanMarsmissions.Herecognizedthattherealobjectivewastocreateanewandbiggerpie,nottosimplydecide how to cut and subdivide the remaining pieces of an existing, dwindling,smallone.Withitsproximityandknownresources,theMoonofferedthepossibilityofearlyaccomplishment,butmoreimportant,itofferedawaytomakeaneventualMars mission easier and more affordable. Thus, the president decided that theobjectiveswere tobebothMoonandMars.24 In this sense,hewas reinstating thegoals of the abandoned Space Exploration Initiative that his father had proposedfifteen years previously. But this return to the Moon was different. In his major

policy speech on the new Vision for Space Exploration (VSE), President BushoutlinedtheactivitiestobedoneontheMoon:togotherewiththegoalsofstayingfor increasingperiodsof time to learnhowtomakeusefulproducts fromwhatwefoundthere.Inotherwords,thislunarreturnwasfocusedonsustainedpresenceandthecreationofnewspaceflightcapabilities.

Sustainability and the creation of new capabilities fromwhatwe find in space:these startlingly radical aspects of the new program were largely dismissed orignoredbymanyobservers,whothenwentontocharacterizethereturntotheMoonas merely the prelude to a human Mars mission. This false interpretation of thepurposebehindthenewpolicywaswidespreadwithintheagency,aswellasinthespace community as a whole. The confusion led to immediate and significantproblems formany early strategic decisions on implementing the VSE. ButwhenPresidentBushannouncedthenewVisiononJanuary14,2004,inaspecialspeechatNASA Headquarters,25 space advocates were encouraged. Finally, a coherentdirection had been imposed on what was widely perceived as a foundering,directionlessprogram.Despitetheexpectedcarpingfromsomeinthespacesciencesector,mostagreedthatthenewstrategicredirectionofthecivilspaceprogramwasworthy. The president announced that he was forming a commission chaired byformerSecretaryoftheAirForcePeteAldridgetoexaminewaystoimplementthenew Vision. This commission was to report back to him in six months. To mysurprise,abouttwoweeksaftertheannouncement,IreceivedacallfromtheWhiteHouseaskingmetoserveonthiscommission,anassignmentthatIwasmorethanhappytoaccept.

NASA now had a new direction and the possibility of a fresh start after theColumbia disaster. For lunar scientists and advocates, the new VSE was anintoxicatingpromisetorevisitourobjectofdesire,andtodevelopnewtechnologiesthatwouldenablelong-termhumanpresenceoff-planet.FortheMarscommunity,therewassubduedrejoicingandasomewhatirritatedacceptanceofbeingrelegatedtoa“long-term”objective.Butasthingsprogressed,wesoondiscoveredthatdespitethe clear strategic direction theVSEprovided, following itwasnot going to be soeasy.

O

5ImplementingtheVision

nJanuary14,2004,PresidentGeorgeW.Bushunveiled theVision forSpaceExploration(VSE)duringavisittoNASAHeadquarters.Theproductofalmost

a fullyear’s reviewby theWhiteHouseandNASA, it outlineda strategicpath toreestablishasenseofpurposeanddirectionforthenation’scivilspaceprogram.1TheVSE consisted of four major elements: return the Shuttle to flight to completeconstruction of the International Space Station; develop and build a new humanspacecraft,theCrewExplorationVehicle(CEV),andeventuallyretiretheshuttle;setourspaceprogramonacoursetotheMoonwiththeobjectof“livingandworkingthereforincreasingperiodsoftime”;andeventually,undertakeahumanmissiontoMars.No deadlineswere declared for thesemilestones, although lunar returnwasgiven the scheduling guideline of “as early as 2015 but no later than 2020.”Budgetary direction to support the new Visionwas articulated: a single, one-timebudgetaugmentationofabout$1billionspreadoverfiveyears,withtheremainderof thefundingneededfor the implementationof theVSE,about$11billion, freedupfromexistingfundingthroughtheretirementoftheshuttle,sinceservicingandpreparingitforflightwasalabor-intensiveactivitythatconsumedalargefractionoftheagency’soperationalhumanspaceflightbudget.

The announcement of the new VSE caught many off guard, and although itsreception was mixed in some quarters, the overall reaction to it from most spaceprogramobserversappearedtobepositive.Aspartoftherollout, itwasannouncedthat a commission headed by former Secretary of the Air Force, Edward “Pete”Aldridge,wouldmeet to studyhow to implement thenew spacevisionand reportthevariousoptionstotheWhiteHousewithin180days.

The Aldridge Commissionmet for the first time in early February 2004 in anoffice complex inArlington,Virginia. Iwas a staff scientist at the JohnsHopkinsUniversityAppliedPhysicsLaboratoryatthattime.Theothercommissionerswereplanetary scientists Laurie Leshin and Maria Zuber, astronomer Neil DeGrasseTyson, former Congressman Bob Walker, General Les Lyles, former DeputySecretary of Transportation Michael Jackson, and Hewlett-Packard CEO CarlyFiorina. Most of us had served on various space advisory committees before andknew what was expected of us. At our first meeting, we went around the table,

assessingexactlywhereweallstoodinregardtoourtaskandtheVision.Whileallwere supportiveandexcitedabout thenewVSE,everyoneexpresseda concern fortheneed todevelopand toarticulatea strong rationale fora continuing, sustainedprogram.Perhapswithabit toomuchoptimism,we thought thatwecouldweavesuch a rationale into the report, both as an underpinning logic to ourrecommendations (whatever they were to be) but also for use by both theadministrationandNASAtohelp“sell”theVSEtocongressionalappropriators.

Our work was prefaced with a series of presentations given by the variousadministrativecodesofNASA(SpaceScience,HumanSpaceflight,andsoon).Thesesummaries were designed to inform our group on what the various parts of theagencysawastheirmissionchallengesandwhattheyplannedtodoinresponse.EdWeiler, then associate administrator for space science, gave one of the earliestpresentations.Abulletpointononeofhisslidesread,“activitiesontheMoonwillbeminimizedandrestrictedonly to those that supporthumanMarsmissions.”Itwassurprisingtoseethisstatement;afterall,PresidentBush’sspeechhadbeenspecificand concrete about activities for the Moon (something unusual in a presidentialspeech),indicatingthatlearningtoliveandworkontheMoonforincreasingperiodswasamajorobjectiveoftheVSE.ItbecameclearthatWeiler’sunderstanding,alongwith several others at the agency (especially in the Space Science section) wassomething entirely different from the straightforward language of the Vision.Hetook the position that the VSE was almost entirely about human Mars missions.WhenIpointedoutthisdiscrepancytoWeiler,myconcernwasdismissedwithoutameaningfulresponse,onlyacommenttotheeffectthat“thisishowweunderstandthe Vision.” Almost immediately, the lunar parts of the VSEwere deemphasized,withagradualyetperceptibleshifttowardsusingtheMoonasameretestinggroundfortheMarsmission.2

Iwasable to trace thisevolution ina seriesofbothofficialand internalagencydocuments, ending with the Weiler interpretation of “minimal activity on theMoon.”Theoriginsofthisintellectualdisconnectgobacktothelate1990sandearly2000s,withsomethingcalledtheNASADecadalPlanningTeam—DPT,latercalledNEXT, forNASAExplorationTeam.3CharteredunderAdministratorDanGoldin,thisgroupwas taskedwithmappingapath forhumanmissionsbeyond lowEarthorbit,ultimately leadingtoaMarsmission.AlthoughGoldinwas fixatedonMars,theDPTfocusedprimarilyonnearertermobjectivesincislunarspace,includingthelibration points—that is, points in space that remain fixed in relation to Earth,Moon, and Sun—and the lunar surface. Additionally, both asteroid missions andmissionstothemoonsofMarswereconsidered.Therationalebehindthestepping-

stoneapproachwastoofferflexibilitytosomefutureadministrationthatmightbeinterested in a long-term, deep space goal forhuman spaceflight.The agency stillmaintained their fixation with Mars, and the idea was prevalent throughout theDPT that any activity on the lunar surface detracted from and delayed theMarsmission.4 In consequence, mission planning before the VSE did consider lunarmissionsbutonlyinacursorymanner.

Although we knew by 2000 that the poles of the Moon probably harbored icedeposits,waterproductionfrompolardepositswasnotincludedaspartofanylunarsurfacearchitecture.Moreover,thekeyfindingfromClementinethatareasofquasi-permanent sunlight could be found near the poles (enabling sustained permanentpresence on theMoon)was acknowledgedbutnot integrated into a useful surfaceoperationsplan. In fairness,duringthoseyearsof theDPT-NEXT, theagencyhadno authorization to proceed beyond the ISS and shuttle, so their studies, whileinterestingandusefulintermsofwhatcapabilitiescouldbedeveloped,couldnotbeimplementedorevenintegratedintoanylong-rangestrategicplan.

The thrust of agency efforts in this era was the emphasis on the quest forextraterrestriallife,5boththeactualsearchforlifeelsewhereanduseof“thequest”as a driving political and programmatic rationale for exploration beyondLEO. Inpart, this was a natural outgrowth of the parallel and continuing robotic Marsprogram.However,thatintellectualmilieumeantthatwhenhumanmissionswereto be considered, lunar surface activities (which were thought then to be largelyirrelevanttostudiesoflife’sorigins,anincorrectbutwidelyheldbelief)tendedtobedeemphasized. I believe that this fixationwith finding life onMars held and stillholdstheagencyhostage,unabletoconsideractivitiesontheMoontobeanythingother than a technology demonstration in preparation for a humanMarsmission.Thus,whentheVSEwasannounced,althoughconsiderableverbiagewasdevotedtodetailing the activities to be undertaken on theMoon, the agency heard only onewordasitsdestination:Mars.Inconsequence,thepreviousfocusonthe“searchforlife”carriedovertobecometheunderpinningsciencerationaleforthenewVSE.

TheVision,asoriginallyarticulated,wasspecificandquitedifferent.TheMoonintheVSEwastoserveasalaboratory,aworkshop,andalogisticsdepot.Theideawastolearnhowtousethematerialandenergyresourcesofspace(includinglunarpolarice) to create new spaceflight capability.6 Many misunderstood or dismissed thislatter concept. TheMoon’s role in the VSEwasmischaracterized as “landing theMarsspacecraftontheMoonfortestingandrefueling.”Infact, thesignificanceofthe Moon in the Vision was to use it to develop technologies useful for futuremissions, as well as to develop lunar resources to fuel the missions to distant

destinations.ThisconceptwasthevisionintheVSE.The Aldridge Commission held public meetings in Dayton, Atlanta, San

Francisco,NewYork, andWashington,D.C., to gather information and testimonyfromlocalexpertsand togive thepublicachance toweigh inwith theirconcernsand hopes for the direction of human spaceflight. Subgroups of the commissionundertook fact-finding trips to the various NASA field centers with the aim ofunderstanding whether all of the centers were needed to execute the VSE, orwhether a differentmanagementmodelmight be employed tomakeNASAmoreefficient.To evaluate the possible roles of the commercial sector in implementingtheVSE,wegatheredaconsiderableamountofinformationfromthespaceindustry.All thewhile, I attempted to revector the effort back toward its original intent oflearning how to use space resources.7 Finally, we examined the configuration ofmanagementwithinNASAanddeliberatedonhowtomaketheagencybothmoreefficientandmoreaccountableinthecompletionofitsassignedtasks.

The Aldridge Commission report was issued in July 2004.8 Even though itsrecommendations were reasonable and moderate, only a few were seriouslyconsidered and even fewer were eventually implemented. Our idea for NASA toprocuredeliveryof goods andpeople to lowEarthorbit eventually resulted in theCommercial Cargo and Crew program. Engineering management buzzwords like“spiral development”were eagerly embraced by the agency, but such enthusiasmdidnotmove theball forward toanygreatdegree.Some ideaswereconspicuouslyignored,suchasresurrectingtheNationalSpaceCounciltoactasanoversightbodyfor NASA and the idea to turn field centers into federally funded research anddevelopmentcenters(FFRDC),amodeofoperationinwhichauniversitymanagesan agency field center—NASA’s Jet Propulsion Laboratory, managed by Caltech,operatesthisway.Thisstructurepermitseasierpersonnelrecruitmentandturnover,anditallowscenterstoseeknewbusinessfromtheprivatesector—featuresdesignedto keep field centers technically strong and their management more nimble andresponsivetorapidlychangingfiscalandprogrammaticconditions.

That the commission’s report was largely tabled is probably not too surprising.However,IwassurprisedatwhatIperceivedtobetheextremeinertiaoftheagencyingetting theVSE started.Theobvious first step in any lunar returnwas to fly arobotic mission to follow up on the Clementine and Lunar Prospector polardiscoveries. Mapping the Moon globally at high precision and resolution wouldcreateadatabaseofstrategicknowledgetohelpplanandexecutefuturemissions.Anagency call went out to the scientific community (called an “Announcement ofOpportunity,”orAO)toproposeinstrumentstoflytotheMoononamissioncalled

theLunarReconnaissanceOrbiter (LRO).Among themany specifications of new,required strategic datawas one to “identify putative deposits of appreciable near-surfacewater ice in polar cold traps at ~100m spatial resolution.”9 At the JohnsHopkinsUniversityAppliedPhysicsLaboratory,Iwaspartofateamthatproposedan imaging radar for the LRO mission to address this requirement.10 We alsoproposedflyingasmaller,lesscapableradarinstrumentthatcouldfitontheIndianSpaceResearchOrganization’sforthcomingChandrayaan-1missiontotheMoonasaguest payload.Radarwould beuseful tomap the shadowed, cratered regionsnearthepoles,dataneededtostudytheRFreflectionpropertiesoftheinteriorsofthesecraterstodetermineificemightbepresentthere.

To our surprise, the radar instrument (Mini-SAR) was selected for India’sChandrayaan,alongwithaspectral imager(MoonMineralogyMapperorM3)asasecond American guest payload—but not for America’s LROmission. In fact, theselectedpayloadforLROcontainednoradarinstrumentatall.Instead,toinferthedistributionofwater,aRussianneutrondetectorwaschosen,adesign thatexpertstolduswasprobablyinadequatetoproducehydrogenmapsofthepolesatthehighresolution required by the AO. These decisions,made in early 2005, caused greatconcern among those of usworking toward lunar permanence and resourceuse; itappearedtobeaselectiondesignedmoretocheckoffaboxonachartratherthanone geared toward the gathering useful strategic knowledge. Our rejection wasappealed to the Administrator of NASA and after some wrangling, the Mini-RFradar was approved for flight on LRO. This administrative fracas led to someresentment toward the radar experiment by some of the LRO project people atNASA–GoddardSpaceFlightCenter.OurMini-RFexperimentwasaccommodatedontheLROmissionasa“techdemo,”andalthoughtheprojecthadbeendirectedbyseniormanagementtoaccommodateMini-RF,our teamhadto fightforobservingtimeandspacecraftresourcesduringthenominalmission.

FlyingtheradarontheIndianmissionwasmoregratifying.11Chandrayaan-1wasIndia’s firstmissiontodeepspaceandtheIndianswerequiteexcitedandproudoftheir maiden efforts in trans-LEO spaceflight. The Chandrayaan spacecraft wasrelatively small,about the sizeofClementine,yetverycapable. It carriednotonlyprecision imaging cameras but also flew instruments to map the mineralogy andchemistryofthesurface.ThetwoAmericanexperimentsflownonChandrayaan,ourMini-SARradarinstrument(builtbyRaytheonandAPL)andtheMoonMineralogyMapper(builtbytheNASAJetPropulsionLaboratory)hadtogetapprovalfromtheStateDepartmentbeforewecouldflythemtotheMoon.Iwastoldatthebeginningof this effort that because of sensitivities to export control issues, it was highly

unlikelythatwecouldgetpermissiontoflytheMini-SARonIndia’smission.Butitturned out that our application to participate on Chandrayaan coincided with apresidential-level initiative to improve US-India relations. As a result, the StateDepartment was very supportive of our effort. A last-minute intervention by theWhiteHouse led to theapprovalof theexport license.Mini-SARbecame the firstAmericanscientificexperimenttoproposeandbeselectedtoflyonanIndianspacemission.

I made almost a dozen trips to India over four years. Each one-way journeyrequiredroughlytwenty-sixhours intransitandlastedonlyafewdays; thenearlytwelve-hour time difference between India and America played havoc with myinternalclock.TheupsidewasthattheIndianswereapleasuretoworkwith.TheywereenthusiasticaboutgoingtotheMoonandtheirmissionreceivedalotoflocalpublicity.WheneverItoldanyonewhyIhadcometoIndia,theuniversalresponsewas excitement andan eagerness to learnmore about themission.After selection,the actual work of flying an experiment in space largely involves attendance atinnumerablemeetings,where thearcanedetailsofeach systemandeverypartaredescribedanddebated.Duringdesign,assembly,and test, scientistshave little realworktodo;wedetermineanddefinetheparametersoftheinstrumentanddeviseaplantocollectthedata,butordinarily,ourworkhappensduringandaftertheflight,whenthedatastreamsdownandmustbereduced,formatted,andinterpreted.Manyofusviewpreflightworkaspayingduesforthefunworktofollow.Andasmanycanattest,allofthisplanningandeffortcanjustaseasilygoupinflamesifthelaunchdoeslikewise.

TheLROversionoftheinstrumentwasabitmorechallenging.TheLROradarwastooperateintworadiofrequenciesattwodifferentgroundresolutions,buttheMini-SARandMini-RFinstrumentswerebasicallythesame.Intermsofoperationtime,ChandrayaanwasscheduledtolaunchaboutayearbeforeLRO.Itwashopedthat we would obtain full data for both poles from Chandrayaan, which in turnwouldhelpusplan to takehigh-resolutiondataof interestingareaswith theLROMini-RFbuild.Duringanextendedmissionandwithalittleluck,wemightevenbeable to collect enough data to make a radar reflectance map of the entire Moon,detailingslopedistributionsandlocatingjaggedrockfieldsonaglobalbasis.

TheFateoftheVSEatNASA:What’stheMission?Althoughmuchofmytimewasspentworkingonthetworadarinstruments,Iwasalso on a number of advisory and analysis groups at NASA dealing with the

implementation of the lunar phase of the VSE. Once the Aldridge Commissionsubmitteditsreport,thenewExplorationSystemsMissionDivision(ESMD)beganitsprocesstodefinethespacecraft,dubbedProjectConstellation,12andthemissionsthatwould constitute our nation’s new space program.Despite the clear, strategicdirectionNASAhadbeengivenregardingtheVision,inthoseearlyplanningstages,therewasgrowingcauseforconcernaboutthefateoftheVSE.

TheheadofESMDatNASA,AdmiralCraigSteidle,whocametotheVSEfromanother large engineering project, the Defense Department’s Joint Strike Fighterprogram, had no spaceflight experience. The then-current vogue in largeengineering projects was a technique called spiral development.13 The spiral plancalledforfoursequentialstages:developrequirements,analyzerisks,buildandtest,andevaluateresults.Theproductbecomesthenew“block”toberefinedinthenextspiral.Anothername for thisprocess is“builda little, test a little.”The idea is topursue the most promising designs by not committing to a final version untilsignificant experience and test data are acquired. NASA’s devotion to this newmanagementvoodoowasreminiscentofmanypreviouslyembracedbusinessschoolfads, such as Total Quality Management (TQM). One notable employer of spiraldevelopment, amazingly enough, was the F-35 Joint Strike Fighter program, theprojectwhenceSteidlecameandonerenownedforbeingyearsbehindscheduleandbillionsofdollarsovercost.

Thus,fromthefirststep,withthedevelopmentofrequirementsandaseeminglyendless exercise called technology “road mapping,” the VSE at NASA started offslowly—and then tapered off. Many different experts in science and engineeringwere brought together at great time and expense to opine on what the newspaceflightsystemshadtoaccomplish,inwhatorder,andtowhatdegreeoffidelity.Thisinvolvedbuildingcomplicatedspreadsheetswhosecontentswerepopulatedbytechnologies, instruments, andknowledgeneeds.Theproblemwith this activity isthat too often, problem definition becomes a substitute for actual programmaticprogress,sincecriticaldecisionscanalwaysbedeferredwhileawaitingbetterdefinedormoreperfectlyunderstoodrequirements.

Lestitseemthatnoprogresswasbeingmade,therewasoneactivityinthepost-VSEannouncement era thatwarrants specialmention.AssociateAdministrator forSpaceflightBillReaddyhadpulledtogetheraninformalstudyteam(takenfromhissection of engineers and experts) to examine a possible path to implementing theVSE.While theagencyhadan internal“red team/blue team”studyeffort,whichcame up with the lunar “touch-and-go” concept, Readdy put together what wascalledthe“GoldTeam,”whosemandatewastoexamineunorthodoxapproachesto

implement the Vision. The Gold Team looked at the issue of developing a newhumantrans-LEOcapability,whileatthesametimereturningtheshuttletoflightandcompletingtheconstructionoftheISS.

TheGoldTeamfoundthattheoriginalchargetotheagency—toreturntoflight,finishbuildingtheISS,anddevelopanewhumanspacevehicle,allwiththeaimofreturningtotheMoonby2015—wasachievableifcertainarchitecturalchoicesweremadeearly.Themostsignificantfeatureoftheirapproachwastoretaintheshuttlelaunch infrastructure to support the first twomilestonesand thenuse thatasset tobuildtheshuttleside-mountheavyliftlauncher,aderivedvehiclethatusedshuttleengines, external tank, solid rocket boosters, and all of the existing Capeinfrastructure. The advantage of shuttle side-mount was that by using existingpieces,itwouldrequireminimalnewdevelopment.Aswillbecomeclear,thereasonthatProjectConstellationwascancelledisrootedinescalating,higherthanexpectedearlydevelopmentcoststhatcontinuallypusheditsprojectedfirstflightfartherandfarther out into the future. IfNASAhad chosen to go down the path of theGoldTeam,wewouldhavecompletedtheISSandretiredtheshuttleonschedule,andthenewshuttleside-mountwouldhavebeenreadytoflyhumansby2015.

The advantage of the Gold Team approach was that by adopting shuttle side-mount,mostofthedevelopmentcostsfornewdeep-spacesystemscouldbefocusedwhere they weremost needed: on the new CEV and a robust program of roboticprecursormissionstotheMoon.TheCEVatthisstagewasundefined;itcouldhavetaken the shape of an Apollo-type capsule, as it ultimately did under theConstellation program as the Orion spacecraft, or it could have been the moreflexible“bentbiconic”design,14anaerodynamicallyshapedbodysimilartothatofthe Blue Origin commercial spacecraft. This latter design could have served as apathfinderdevelopmentforaMarsentryvehicle,astheyhavesimilaraerodynamicshapesandwouldbeabletolandonitstailunderthrust,permittingsoft,drylandingat the launch site, like the shuttle. Separate crew modules derived from ISShardwarewouldserveascislunartransfervehicles.

TheoriginalVSEcalledforasignificantandrobustprogramofroboticmissions,but the Gold Team took this further by using such missions to emplaceinfrastructure on the Moon. A large robotic lander was planned, designed to usesolar-electricpropulsion(SEP)andlargesolararraystospiraloutslowlyfromLEOtotheMoonandthenuseaLOX-hydrogenrockettolanduptoseveralmetrictonson the lunar surface. After landing this payload, amobile lander platformwouldseparateandthelargesolararraysthatpoweredtheSEPwouldbecomepartoftheelectricalpower-generatinginfrastructureoftheoutpost.Throughthisapproach,we

wouldbegintoestablishapermanentlunarsurfaceoutpost,afacilityeventuallytobe used by humans. By predeploying habitats and subsystems on theMoon usingunmanned spacecraft, we couldmake the human-rated systems smaller (reducingdevelopment costs), yet adequate (taking advantage of preemplaced assets). Theinnovative use of robotic missions by the Gold Team was a significant departurefromordinaryagencypractice,wherebyroboticmissionsareusedprimarilyfortheacquisition of scientific and engineering data, which are then used to design thehumanvehicles. Instead, theGoldTeamadvocatedusingroboticassets in tandem,andinparallel,withthehumanspacecraftandmissions.

AlthoughtheGoldTeamarchitecturalapproachhadmuchtocommendit,bothintechnicalandinfiscalterms,Readdywasnottheagencypointmandesignatedtomake these choices.Steidleand theOfficeofExplorationwereawareof thisworkbutdidnot take it seriously, insisting insteadonpursuing their roadmappingandspiral development approach—which, in this case, consisted mostly of deferringdecisions indefinitely. The only effort proceeding to actual flight was LRO—planned as the first in a series of robotic exploration precursor missions sent byspacefaringnationsaroundtheworldtotheMoon.

ANewAdministratorandtheESASEarly in 2005, Sean O’Keefe announced his decision to leave NASA to becomechancellorofLouisianaStateUniversity.MichaelD.Griffinwastappedasthenewadministrator,comingtoNASAwithanimpressivebackgroundofengineeringandmanagementexperiencebackedupbysevenuniversitydegrees.15IknewMikefromtheSynthesisGroupdays,whenhewas one of our seniormembers, and from theClementine project, where he was deputy director for technology in the StrategicDefenseInitiativeOrganization.GriffinalsoservedastheassociateadministratorforexplorationatNASAduringtheSEIdays,althoughaswehaveseen,thatprogramwasabandoned.Avisionary,Mikewasand isa strongadvocate foravigorousandexpansivehuman spaceprogram.Around the timeof theVSErollout,GriffinhadledastudysponsoredbythePlanetarySociety,outlininganarchitectureforhumanmissions beyond LEO, primarily driven by the requirements for human Marsmissions.16Thisplanwasnotableforitsuseofacrewlaunchvehiclederivedfromasingleshuttlesolidrocketbooster,aninnovationthatgeneratedmuchcommentandsubsequentcontroversy.

Griffin decided that NASA had wasted the last eighteen months with roadmappingexercisesandspiraldevelopmentandsummarilydismissedSteidle.Inhis

place,GriffinbroughtinScott“Doc”Horowitz,aformerastronautandtheengineerwhohadcomeupwith the idea for the“stick,” theSRB-based launchvehicle.Tomove the ball down the field, one of the first things Griffin did after assumingagencyleadershipwastoconveneanadhocstudygrouptodesignanarchitectureformissions beyond LEO. This effort, dubbed the Exploration Systems ArchitectureStudy (ESAS),17 was conducted from midsummer to the fall of 2005. The leadengineer was Doug Stanley of Georgia Tech who led a team of mostly NASAengineers fromHeadquarters and the field centers. Iwas amemberof this group,but my involvement was focused only on lunar surface activities and theidentification of possible landing sites. I was not involved in any major decisionsaboutthespacecraftandlaunchvehiclesofthearchitecture.

TheESAS teambeganwitha set of assumptions about the requirements of thenew transportation system and how it would be used. The study embraced therecommendationoftheColumbiaAccidentInvestigationBoard(CAIB)18toseparatecrew and cargo, thought to be a safety issue, although no one could really give alogical rationale for it. There was a sense that launching a rocket with the crewpositioned on the side of the vehicle, like the shuttle, was inherently unsafe,althoughthisspecificideaisnotpartoftheCAIBreport.Itisdifficulttojustifythisedict on technical grounds, since 134 shuttle flights safely launchedpeople in thisconfigurationand in theoneaccident thatoccurredduring launch,Challenger, thecrewandtheircabinsurvivedtheexplosionandwouldhavelivedhadthecabinbeenequipped with parachutes; they were instead killed on impact with the sea. Thisgroundrulewas importantbecause itmeant thatadoptionofa shuttle side-mountdesign as a launch vehicle would likely require three vehicles per lunar missionrather than two, a consequence later used to justify the elimination of the side-mount option. The new architecture was mandated to serve ISS crew and cargorequirements, in addition to lunar surfacemissions, even though the then-currentplan called for endingAmericanparticipation in the ISSaround the time that thenewsystemsweretocomeonline.Certainlythiswasnotthefirsttimeinthehistoryof the space program that an architecture was devised under the constraints ofarbitraryand illogicalgroundrules,but seriousconsequenceswere toemergefromtheseboundaryconditions.

TheESASworkcameupwithaninterestingsolutiontothearchitecturalproblemof launch, something they called the “1.5 launch vehicle” solution. In brief, thestudyadvocatedthedevelopmentoftwodifferentlaunchvehicles:asmaller(20ton)crewlaunchvehicleidenticaltothePlanetarySociety’sSRB“stick”rocket(AresI),and a larger (130 ton) shuttle-derived, inline vehicle (Ares V) to carry cargo and

heavy payloads (launching two differently sized vehicles led to the nickname). Asinglemissionwouldusebothvehicles; thelunarlanderandEarthdeparturestagewould be launched on the large Ares V as “cargo,” while the crew would belaunchedseparatelyonthesmallerAresI.ThetwospacecraftwouldrendezvousinEarth orbit, dock, and then depart for the Moon. The rest of the mission profilefollowed the same pattern as the Apollo missions: lunar orbit insertion, landing,ascent,rendezvous,andreturntoEarthintheOrionCEV.BoththeOrionCEVandtheAltair lunar landerwere larger,more capableversions of theApolloCSMandLunar Module. Because of Constellation’s similarity of appearance and missionprofile to the Apollo missions, Mike Griffin once referred to this architecture as“Apolloonsteroids,”anunfortunatecharacterizationthatreverberatestothisday.

TheESASreportwasreleasedinOctober2005tolessthanuniversalacclaim,withmany noting the similarity of the new plan to the old Apollo template. In fact,althoughthenewplanwouldcreateconsiderablecapability,theflyingofindividual,one-offmissionswherebymost pieces are discarded after a single use, reverted usback toanearliereraof the spaceprogram.As inApollo,only thecrewcommandmodule(Orion)wouldreturntoEarth.Theindividualmissionswouldcarryalargercrew of four and stay on the lunar surface longer, up to two weeks. The largecapacityof theAltair lunar landermeant that significantcargocouldbeplacedonthe Moon, permitting an outpost to be established with a minimal number oflaunches.

An importantpoint tounderstandabout theESASarchitecture is that itsheavylift launchvehicle (AresV, starting out at 130metric tons, but expandable to 160metrictons)isscaledforhumanMarsmissionsstagedentirelyfromEarth;itsutilityforthelunarmissionsisgenuinebutonlyincidental.AmissiontotheMoonrequiresroughly100–120metrictonsinLEO(dependingonhowthemissionisconfigured,itsequipmentanddestination).Thiscouldbeaccomplishedwithtwomedium-classheavy lift launches (70metric ton; shuttle side-mount) or the launch of a single,largevehicle (SaturnV-class).TheAresV ismuch larger thanwhat isneeded forroutinemissions to theMoon.But if the requirement is todeliverpiecesofa500-metric-ton Mars spacecraft to LEO, then transporting it with as few launches aspossible greatly reduces overall risk. Clearly, the ESAS was looking ahead to thefuturewhere itwas thought thatNASAwould get only one chance to develop anentirelynewspacetransportationsysteminthenewcenturyanditsobjectivewastoplanttheAmericanflagonMars.Theseedoftheproblemhadbeenplantedandthefuture of spaceflight envisioned through the lens of the Apollo program—withdisposable spacecraft and everything launched from Earth—became unaffordable

andthusunsustainable.Itstillis.Moreimportant,itdiscardedtheoriginalpointoftheVSE:tolearnhowtousethematerialandenergyresourcesoftheMoontocreatenewspaceflightcapability.

Lest anyone think that this latter point was unclear or had been inadequatelypresented—after all, the VSE had been unveiled in a relatively brief presidentialspeech two years previously—in March 2006, Presidential Science Advisor JohnMarburgergaveoneofthefinestspeechesIeverheardonthemeaningoftheVSEand on a rationale for spaceflight in general.19 Speaking at the annual GoddardSpace Symposium, Marburger carefully laid out the physical difficulties ofspaceflightandarticulatedwhytheMoonhasacriticalroletoplayincreatingnewcapabilitiesinspace.Heposedakeyquestion:“Whatisthepurposeofourcivilspaceprogram?” Marburger then stated that “questions about the vision boil down towhetherwewant to incorporate the solar system in our economic sphere, ornot.”And he provided an answer: “For a space program to serve national scientific,economicandsecurityinterests,wemustlearntousewhatwefindinspacetocreatenew capabilities, starting with the material and energy resources of the Moon.”Marburgeralsopointedoutthatsuchamissionhadmuchgreaterlong-termsocietalvalue thanspaceactivities“confined toa singlenearbydestinationor toa fleetingdashtoplantaflag.”BecausetheMoonisclose,reachable,anduseful,itwaschosenasthecenterpieceoftheVSE.Marswasadestinationreservedforthefuture,afterwehadmasteredthenewskillsandtechnologyneededforspacefaring.

Apparently, few in theagencyheardor readMarburger’s speechbecauseNASAeithermisunderstoodtheircharterintheVSEordeliberatelytorqueditawayfromthe intended direction. An Exploration StrategyWorkshop, held in April 2006 inWashington,gatheredaninternationalcadreofabout150spaceexpertsforafour-daymeetingtoidentifywhyweweregoingtotheMoonandhowtobestaccomplishthosegoals.TheboundaryconditionswerethefeaturesandlimitationsoftheESASarchitecture; otherwise, the agenda was completely open. I was stunned by thepremise of thismeeting. The VSE speech of January 2004 was the clearest,mostunambiguousstrategicdirectiongiventothespaceagencybyapresidentsinceJohnF.Kennedy’sApollodeclaration.20Yet twoyears later,NASAdecidedtoconveneagrouptocomeupwitharationaleforlunarreturnandtoenvisionasetofactivitiesoncewegot there.Theagendaforandmindsetof thismeetingconvincedmethattheVSEwasinserioustrouble.

Theworkshopattendeesdeliberatedoverthecourseofthreedays,drawingupsixmajor “themes” for lunar return: human civilization, scientific knowledge,exploration preparation, global partnerships, economic expansion, and public

engagement. Flowing from those six broad-based themes was a “grid” of specificrequirementsandactivities,186entriesidentifyingwhatwouldbecometheinputtothe succeedingLunarArchitectureTeam (LAT).Although theESAS specified thehardwareandmissionprofiles,exactlyhowtheywouldbeused,whicheventsandinwhat order they would take place on the Moon, were yet to be specified. Withworkshopresultshaving“toldus”whyweweregoingtotheMoon,wecouldbegintofocusonthe“how.”

Among the topics tobegrappledwithwere the siteson theMoon tobevisited,whether to set up an outpost or conduct multiple sortie visits, and whichinvestigations to conduct and in what order. The LAT consisted of scientists andengineerswhowouldmeet several timesperyearbutwouldmostlyperform theirworkattheirhomeinstitutions.TonyLavoie,anengineerfromNASA-MarshallinHuntsville, chaired the first LAT.Tony and I had previouslyworked together onplanning the later-canceled second lunar robotic mission, a lander and roverdesignedtomapandcharacterizetheicedepositsinthepermanentlydarkareasnearthepoles.WeknewsomethingaboutthelunarpolarenvironmentfromClementineandLP,andthesoon-to-flyLROwouldadddetailedknowledgethatwouldallowustopicktheoptimumlandingsitesforsurfaceactivities.

ThefirstLATcameupwithsolid,defensibleconclusions,especiallyinregardtomission mode and priority activities.21 The most important decision made was tofocus lunar returnon the establishment of anoutpostnear oneof thepoles of theMoon;whichpolewastobedecidedafterLROandsomesurfaceroverdatahadbeencollected.Theprincipalreasonforanoutpostisthatyoucanconcentrateassetsatasinglelocalityandrapidlybuildupcapability.Thealternateapproachistoconductsortiemissions,whichpermitvisitingmanydifferentsiteswithwidegeographicandgeologicdiversitybutpreclude theconcentrationofassets, since the siteswouldbeabandoned after each mission. The sortie strategy was the Apollo template writlarge; the outpost approach would mean permanence, or at least long-termhabitation, and the opportunity to build a production-level resource processingfacility.UnlikemanywithinNASA,Lavoieclearlyunderstoodtherealmeaningofthe VSE: to return to the Moon and learn the skills needed for extended spacepresence and capability. Under his leadership, for the first time since itsannouncement, the VSE began to move toward a mission more inline with itsoriginalintent.

Despite its many good deeds, the LAT activity was still entrained within theNASA system and hence, was required to address the 186-entry “spreadsheet ofdeath,”aswecalledthetableofactivitiesandeventstobeaccommodatedwhileon

theMoon.Thepracticaleffectof thiswas todiffuse theLATeffortaway fromitsprimarymission direction—a resource-processing outpost—into a nebulous,NASAlunarexplorationmission.Mostinsidiously,thelunar“touch-and-go”onthewaytoMars, the “real” objective, slowly crept back into the architecture.This happenedlargely during the second round of architectural planning (imaginatively named“LAT-2”) inwhich sortiemissions became the new baseline. In part, thiswas anagency reaction to an outcry during the public rollout of the LAT-1 plans inDecember 2006.22 The usual suspects—the Planetary Society, media, variousindividuals—were greatly concerned that a significant amount of time and effortwastobeexpendedontheMoon,thusdelayingtheirApollo-type“sprint”toMars.Acommonphraseduringthis timewastheexpressionofdesire toget toMars“inmy lifetime,” a requirement not derived from any programmatic principle I candiscover.Inshort,the“sprinttoMars”cabalwithinandoutsideoftheagencyhadstruckback.

ThereportoftheLAT-1teamattheendof2006wasthehigh-watermarkoftheVSE.Althoughmanyintheagencystill refusedto“understand”preciselywhyweweregoingtotheMoon,asolid,logicalplanofactionhadbeendeveloped.BoththeChandrayaan-1 and LROmission developments were proceedingwell, as was ourworkonbuildingtheMini-RFimagingradarstomapthepoles.BecauseLROhadgrown inmassandhadoutgrown its originalDelta II launchvehicle, anewAtlasboosterwithextrapayloadcapacitywasprocured.Consequently,ESMDlookedforapossiblesecondarypayloadtosendtotheMoonwiththeLROspacecraft.Aconceptwasproposedby theNASA–AmesResearchCenter to crash theexpendedCentaurupperstageoftheAtlaslaunchvehicleintooneofthepolesoftheMoonandobservetheejectaplumeofthatimpactwithasmallspacecraftfollowingbehind,unliketheprevious Lunar Prospector effort in 1999, which attempted to observe the ejectaplumeonlywithEarth-basedtelescopes.IficeispresentontheMoon,itwashopedthatwewouldobserve it in thisplume.Thisadd-onmissionwascalled theLunarCraterObservationandSensingSatellite(LCROSS).23Itwassomethingofagamble,sinceitmightmissanyputativeicedepositsorfailtoseethosethatarepresent,butwasthoughttobeworthtrying.Asitturnedout,thismissionwouldbethefirst—andtodate,theonly—groundtruthforthelunarpolesthatwewouldget.

TheDeclineandFalloftheVSEAs the momentum to demote the Moon’s role in the Vision grew, ProjectConstellationstartedtorunintotechnicalissuesandmassgrowth,andconsequently,

budgetaryproblems.OneissuewasthesizingofthenewOrionspacecraft.Inordertoaccommodate its larger crew with amenities such as a kitchen and a toilet, thedecisionwasmadeduringtheESAStoadopta5-meterdiameterforthevehicle(theApollocommandmodulewas3.9metersindiameter).Thislargerspacecraftmighthavemadetravelaroundcislunarspacemoreenjoyable,butsuchcomfortcameataseriouscost.TheincreaseinsizeandmassmeantthatOrionoutgrewitsAresI(“thestick”)launchvehicle.DespiteanattempttosolvethisproblembyaddinganothersolidrocketmotorsegmenttotheAresI,nowwithafive-segmentfirststage,itwasfoundthattoachieveorbit,thevehiclewouldneedtofiretheservicemoduleengine,much as the shuttle orbiter used its orbital maneuvering engines to finalize itsattainmentofLEO.Thisissuewasaccompaniedbyconcernsoverahigh-frequencyvibration called thrust oscillation during the burn of the Ares I first stage solid-propellant motor; it was feared that this thrust oscillation could temporarilyincapacitate the crew during critical abort phases of the ascent. Although theseproblemsallhadsolutions,theproblemwasthattheydidnothaveany“no-cost,no-mass”solutions.

The basic problem with Orion was that it was oversized for its role as simpletransporttoandfromLEOtosupporttheISS(partoftheESASgroundrules)andevenasacislunarvehicle.Worse,itwasundersizedinitsroleasaMarsspacecraft,beingusefulforonlytwophasesofthemission:crewdeparturefromtheEarthandaerothermalentryuponreturn.Fortrue, long-durationflights,Constellationwouldneed to carry a separate habitation module. But such a requirement negated therationaleforprovidingOrionwithakitchenandtoilet,whichdroveitslargersizetobeginwith.Thus,wewere (andstillare)developinganewhumanspacecraft thatwassimultaneouslytoobigforitsearlyusesandtoosmallforitsintendedlaterone.

As technical issuesgrew, theagency’s annualbudget requestsbegan to increase.When budgetary increases failed to materialize, the scope of agency activitiesdecreased.Anearlycasualtyofthisnewausteritywasthelunarroboticprogram.Thesecond roboticmission to theMoonwas to have been a surface lander and rover,designedtofollowuponthewaterdiscoveriesfromorbitandmeasurethetypeandquantity of water present in the surface, critical information needed to use theresource. Other robotic missions were designed to emplace infrastructure such ascommunications relays so that landings at the poles and on the far side could beundertaken,and to test resourceextraction techniques suchaswaterproductiononthe surface. Because of budgetary pressures caused byConstellation’s developmentproblems,all thesemissionsweredeferred to“later,”whichbecame“never.”Thisdeferraloftheroboticprogramwasablatantneglectofthespecificdirectionwithin

theVSE that a “series of roboticmissions to theMoon be undertaken” as part oflunarreturn.

Few observers in Washington ever thought that the VSE would be fullyimplemented with the minimal new investment that NASA had been promisedduringtheBushrollout.Butitseemedtomanythattheagencywasnottryingveryhard tomaximize the leverage provided by the use of legacy hardware.TheAresvehicles,althoughbaseduponanadaptationofshuttlehardware,requiredsomanymodifications that it became a completely new development. And given theproblemswithaccommodatinganoversizedOrion,mostdidn’tevenwant to thinkabout developing its necessary companion, the behemoth Altair lunar lander,supersizedbecauseofitsdualroleasaself-containedhumanlander/habitatandanautomated cargo lander. There were increasing complaints about Constellation,initially from the space community peanut gallery. Over time, criticisms startedshowingupincongressionalhearings.Itdidn’thelpmattersthatsomeseniorNASApersonnelwereincapableofexplainingexactlywhyweweregoingtotheMooninthefirstplace, includingsomewhohadbeenassignedthis taskaspartof their jobdescription.24

Figure 5.1.Mini-RF radarmosaic of thenorthpole of theMoon. Small craterswithbright interiorsnear the

northpole(arrow)areprobablyfilledwithwaterice.Morethanabilliontonsofwatericearelikelyavailableat

eachpole.(Credit5.1)

Meanwhile,progresscontinuedonthetworoboticlunarmissionsthathadalreadybeenapproved.Inthefallof2008,IonceagainmadethelongjourneytoIndia,onlythistimetotheSHARcomplexnorthofChennai,ontheeasterncoastwhereIndialaunches its rockets. SHAR is located on a flat, marshy coastal plain, similar insettingandambiancetoourownCapeCanaveral.OnOctober22,2008,afterafewdaysofconstantmonsoonrain,wefinallylaunchedChandrayaantotheMoon.Asit

arced eastward over the IndianOcean, Iwas able to catch a quick glimpse of thedepartingrocketthroughamiraculousbreakinthecloudcover.25Followingafour-day journey, Chandrayaan inserted into orbit around the Moon and begantransmittingdatabacktoEarth.IwasattheMissionControlCenterinBangaloreforour initial data collect in early November, as a single strip showing some lunarcraters near the north pole was downloaded. With our instrument working, webeganourfirstmappingcycleinearlyFebruary2009andoverthecourseofthenextmonth,acquirednearlycompletemapsofbothpoles.Itwouldtakeseveralmonthsofanalysisbeforewecouldunderstandwhatall thedatameant—thatwater icedoesexistinquantityinsomeofthecratersnearthepoles(figure5.1).26

The election of Barack Obama as president in November 2008 led to newuncertaintyaboutthefateofProjectConstellationandtheVSE.Duringtheelectioncampaign, Obama made ambiguous statements of support for the space program,firstsuggestingthatmoneyexpendedonspacemightbebetterspenton“education,”butrapidlychangedhistuneduringanappearanceintheelectoralvote-rich,criticalstateofFlorida,wherehepledgedsupportforProjectConstellation.Spacesupporterswerecautiouslyoptimisticuponhisassumptionofoffice.MikeGriffinhopedtostayon as NASA administrator but that was not in the cards and his resignation wasaccepted. While searching for a permanent replacement, Acting NASAAdministratorChrisScolesetestifiedtoCongressthathedidnotknowwhat“returntotheMoon”meantinthecontextofhisagency’sactivities.27Atthetime,IthoughtthatthisstatementbytheheadoftheagencyassignedthejobofimplementingtheVSE was the absolute nadir of the American space experience but unfortunately,evenlowerpointsweretofollow.Eventually,formerastronautandMarinegeneralCharlesBoldenwasnamedasthenewheadoftheagency,withspaceadvocateand“AstroMom”LoriGarverassignedasdeputyadministrator.Completingthiscastofcharacters was Presidential Science Advisor John Holdren, neo-Malthusianenvironmentalistandcriticofhumanspaceflight.28

The first space policy decision of the new administration was to appoint acommitteetoreviewthespaceprogramandmakerecommendationsonwhethertocontinuecurrenteffortsortoreorientitsgoalsand/orthemeanstoimplementthem.This committee, named for its chairman Norman Augustine, formerly CEO ofLockheed-Martin, should not be confused with the earlier, 1990 AugustineCommittee.29 This new Augustine committee conducted “independent” costanalyses,performedbytheAerospaceCorporation,ofcurrentNASAprograms,withaneyetowardpossiblealternatives.Thecommitteeworkedthroughoutthesummerof 2009, holding meetings and listening to testimony from agency engineers on

progresswithvariousdevelopmentsunderwayaspartofProjectConstellation.Thelackoffulfillmentofrequestedlevelsoffundingwasaconstantrefrain.Duringtheirmeetings, the Augustine Committee also heard testimony from other parts of theagency,includingengineersworkingonAresalternativesandthevalueofusinginsituresourcestomakeconsumablesandpropellantontheMoon.Youwilllooklongandhardinthecommitteereporttofindmentionofthisevidence,whichledmanyof us to suspect that the committee was well on its way to a predeterminedconclusion.

The 2009 Augustine committee report,30 given the grandiose title Seeking aHumanSpaceflightProgramWorthyofaGreatNation,outlinedthreepossiblepathsforward.OnepathemphasizedahumanMarsmission,deemedtechnicallyabridgetoofar.AnotherpathdescribedareturntotheMoon,deemedtoooldhat.ThethirdalternativeoutlinedwhatwascalledtheFlexiblePath,deemedjustright.Incontrasttothefirsttwooptions,FlexiblePathadvocatedjourneysbeyondLEOtoavarietyofdestinationsbeyondtheMoonbutshortofthesurfaceofMars.SuchtargetsincludedanL-point,anearEarthasteroid,oroneofthemoonsofMars.Youmightrecallthatthis was the same “path of progress” advocated by NASA’s Decadal PlanningTeam.31 The perceived advantage of Flexible Path was that all of its possibledestinationsare lowgravityobjects, so thatdeep space systemscouldbedevelopedincrementally without the need to simultaneously develop an “expensive” landerspacecraft. The committee had detailed cost estimates for the various optionsperformedbytheAerospaceCorporationtobuttressitsconclusionthatnoviableandaffordablepathforwardwaspossibleunderthebudgetguidelinesgiventothembytheWhiteHouse.

The reaction to the work of the committee was mixed. It was widely andincorrectly interpreted as a slapdownof theConstellation architecture. In fact, thereportnotedthatthechosenConstellationarchitecturewouldcreatethecapabilitiesclaimed for it. However, costing estimates suggested to the committee that anadditional $3 billion per year was needed to meet the chosen schedule goals ofConstellation.AttentionmainlyfocusedontheAugustinecommittee’sFlexiblePatharchitecture, one that promised technology development in the near term andmissionstounspecifieddestinationssometimeinthefuture.Somethoughtthiswasagreatapproach,whileotherspointedoutthatnebulousgoalsandindefinitetimelinesare,ingeneral,notagoodrecipeforaspaceprogram“worthyofagreatnation.”

As always with committee reports, the devil was in the details. Cost estimatesprovidedtothecommitteebytheAerospaceCorporationincludedexcessivelylargemargins and totals came inmuchhigher thanother analysts estimated.Moreover,

the committee had been presented with evidence showing that modifications toConstellationandotheralternatives,suchasshuttleside-mountforheavylift,werepossibleandaffordablewithoutafundingaugmentation.Leverageprovidedbyandcapabilities created through the use of the resources of the Moon to enable bothlunarandmartianmissionsweredocumentedandpresentedtothecommittee.Yet,noneofthesealternativeoptionsweregivenseriousconsideration.

NASA Administrator Charles Bolden was on record making public commentssuggestinghewasnotenamoredoftheVSEgoals,particularlytheoneinvolvingtheMoon.Hewas critical of lunar returnand indicated thatwhilehewas strongly infavorofahumanmissiontoMars,hebelievedthatitwasfarawayincostandtime.Butnomatterwhatnewdirectionhumanspaceflighttook,Boldenstatedthathewasagainst any future change to that direction.32 President Obama’s science andtechnologyadvisor,JohnP.Holdren,indicatedhisdesiretomakeNASAprincipallyresponsibleforglobalmonitoringoftheEarth,withanemphasisonthetrackingofclimatechangefromspace.Itwasclearthatacorrelationofforceswasassemblingtosignificantly change the direction and outlook ofNASA and theUS human spaceprogram.

PresidentObama’sApril2010speechatKennedySpaceCenterinFloridaoutlinedhisadministration’snewspacepolicy.33At firstglance, it appeared toembrace theFlexiblePathoftheAugustinecommittee.Obamacalledforspendingontechnologydevelopment, to be followed byhumanmissions to a nearEarth asteroid.He alsocalledforincreasedeffortstodevelopcommercialcapabilitiestolaunchpayloadstolowEarthorbit.AplannedreturntotheMoonwasdismissedwiththetritephrase,“we’vebeenthere—Buzzhasbeenthere,”areferencetoBuzzAldrin,whohadflownonAirForceOnetoFloridawiththepresident,apparentlygivinghimthebenefitofhisvastspaceexpertiseduringtheflight.

The announcement of this new path effectively ended the VSE. Moresignificantly, it was also the end of any strategic direction whatsoever for theAmerican civil space program; that direction had been replacedwith rhetoric andflexibility. The promise of spaceflight in the future became the standin for realspaceflight in the present. Instead of a mission for people beyond LEO, we weregiven vague promises of “a spectacular series of space firsts.” Inconceivably, arelativelysmall,preexistingprogramdesignedtohelpdevelopcommercialresupplyofcargotoandfromISSwasheraldedasthecenterpieceofAmerica’sspaceprogram—the “new” direction. Gone was the concept of creating a lasting, sustainablespacefaringinfrastructure.Backwasthetemplateofone-off,stuntmissionstoplantaflag and leave footprints on some new, exotic, faraway target—it didn’t matter

which one—sometime in the distant future, the all too familiar “exciting spaceprogram.”

Whatmanyforgotorchosetooverlookwasthatwithlargebipartisanmajorities,the VSE had been endorsed by the Congress in two separate NASA authorizationbills, once in 2005 and again in 2008.34 Understandably, Congress did not reactfavorably to Obama’s new direction for the civil space program. In the new 2010authorization bill, Congress laid out some surprisingly detailed specifications for anew heavy lift launch vehicle. It directed NASA to transform the planned AresrocketsofConstellationintoanewheavylift launchvehicletobecalledtheSpaceLaunch System,35 or SLS, dubbed the Senate Launch System by its critics.Whileenthusiasts for the new direction decried the Congressional actions as pork, thesimplefactwasthatmanyontheHill,sensingthatacriticalnationalcapabilitywasbeingirretrievablylost,wereconcernedwiththeunabated,scheduledretirementofthe shuttle. Orion was retained as the program to develop a new government-designed-and-runhumanspacevehicle.

Interestingly, the resulting 2010NASA authorization bill kept all the potentialdestinationsoftheoldVSE,includingthesurfaceoftheMoon,somethingelsethatmanyhave ignored.Despite the fact that this billwas a partial repudiation ofhisproposedspacepolicy,PresidentObamasigneditintolaw.NASAarchitectureteamsexaminedpossiblehumanmissionsbeyondLEO, including toanL-pointandnearEarth asteroids, but an achievable mission that would materially advance ourspacefaringcapabilitycouldnotbeidentified.Todisguisetheembarrassmentofnotfinding an asteroid that a human crew could reach, the agency embraced thepreposterous ideaof capturinga smallasteroidand returning it toanorbitaroundthe Moon: the Asteroid Return Mission, or ARM.36 At that point, the space rockwould be accessible to a human crewusing theOrion spacecraft, launched on thenewSLSvehicle.This conceptwas roundlycriticized,andmost space stakeholdersreviledandrejectedit,exceptforthosewhohadadvancedtheideainthefirstplace.Congress has yet to embrace theARMand is split on possible future destinations,although it is still consideringapossibleMars flyby,aPhobos landing,anL-pointmission,oreven(gasp!)lunarreturn.Everythingisupintheair—andwearegoingnowhere.

RegroupingSo we arrive at the present: a space program without strategic direction and anuncertain future. We have seen the confusion and chaos that resulted from two

different presidential attempts to set a long-term direction for the space program.Theseeffortsweretorpedoedbyavarietyofeffectsandevents.Primarily, itwasalackofunderstandingoftheobjectivesof lunarreturnordisagreementwiththem.We had experience with humans on the Moon during the Apollo program, andmany, including some inside the space program, could not imagine anything thatpeoplecoulddotherethatwasdifferentthanwhattheApolloastronautsdid—hoparound, collect some rocks, ride in an electric golf cart, and fall down a lot. Thecharacterization of Project Constellation as “Apollo on steroids” did nothing toconvinceandeducatepeoplethattherewerenewandexcitingpossibilitiesinvolvedin lunar return. Those who were offended by the idea that we were simply“repeating the Apollo experience” on the Moon did not notice that in theiralternative program, they were endeavoring to perform that very experience onMars,withasimilarflags-and-footprintsextravaganza.

Figure5.2.FundingforNASAduringthefirstfiveyearsoftheVisionforSpaceExploration.Thelightcoloris

theagencyfundingwithouttheVSE,themiddlecolorispromisedfunding(anadditional$1billion,spreadover

five years with allowance for inflation) and the dark color is actual funding. In contrast to prevailingmyth,

NASAreceivedalloftheVSEfundingthatitwaspromised.

In the years since the demise of Constellation, a common complaint is thatPresidentBushandtheCongressdidnotadequately fundtheVSE.This isuntrue.On the rollout of theVSE, the amount of funding thatNASAwas to receivewasspecified:anadditional$1billion,spreadoutoverthenextfiveyears(2005–2009),afterwhich theagencybudgetwas to riseonlywith inflation.NASAreceived thisfunding,althoughnotinequalamountsoverthatperiodoftime(Figure5.2).37TheadditionalfundingneededtodevelopthenewCEVandlaunchvehicleswastocomefromthe“wedge”producedasaresultofmoneyfreedupbytheshuttleretirement

andtherampdownoftheISSprogram.Additionally,CongressformallyendorsedthegoalsoftheVSEintwodifferentauthorizationbills;thosetwobillspassedwithlargemajoritiesbyaCongressundertherespectivecontrolofbothRepublicans(2005)andDemocrats (2008). Thus, the VSE was a presidential proposal, adopted on abipartisan basis as national policy byCongress and funded at the levels promised.NASAwas taskedwith comingupwith aplan to return to theMoonunder thoseboundary conditions, not to devise an unaffordable architecture and then whineaboutnothavingenoughmoneytodoit.

As we have seen, new data for the poles of the Moon show that the criticalresources of energy and materials are available there in usable form. Thisappreciationrequires thatwerethinkourpurposes inspaceandontheMoon.TheVSEwasanattempttotestanewparadigmofspaceoperations—insteadofbringingeverythingweneedwithusfromEarth,wewouldlearnhowtoaccessandusewhatwe find in space toprovisionourselvesand to createnewcapabilities there.Asweendeavor to break the logistical chains of Earth and become a true spacefaringspecies,thiseffortholdsthepotentialtogiveusunlimitedcapabilitiesinspace.

Whatisthebestpathforward?WastheoriginalplantousetheresourcesoftheMoontocreatenewspaceflightcapabilitytherightidea?Whatcanwedotoadvanceour“reach”beyondLEOintothesolarsystem?Whyissuchathingevendesirable?ThesearequestionsIhopetoanswerinthenextfewchaptersasIexaminethefacts,the potential, the hype, and the possibilities for the future of the American civilspaceprogram.

T

6Why?ThreeReasonstheMoonIsImportant

hroughout all of the various attempts to give our national space program along-term,strategicdirection,theMoonhaswaxedandwanedinsignificance.

DespitemanyattemptsoverthelastthirtyyearstoignoreitorfocusexclusivelyonroboticspacescienceorhumanmissionstoMarsortheasteroids,thelogicoflunarreturnhasnotbeenrefuted.Undeniably, theMoonwill figureprominently inanyplansforhumanspaceflightbeyondlowEarthorbit,ifnotbytheUnitedStates,thenbysomeothernationwiththeforesightandthewilltotakethelead.

Previous attempts to define the “mission” on theMoon—the quest for variousrationalesfor lunarpresence—hasproducedmultiplethemes,goals,andobjectives,themostinfamousbeingthesixthemesand186objectivesadumbratedatthe2006NASAExplorationWorkshop.1Itreallyisn’tthatcomplicated.Iwillattempttocutthrough this programmatic fog in order to examine the fundamental reasonswhytheMoonisnotmerelyimportantbutalsocriticalforthedevelopmentofpermanentspaceflightcapability.Whateverlong-termspacegoalweadopt,theMoonwillplayakeyroleinenablingustoachievethoseobjectives.ThevalueoftheMoonliesinthree principal attributes: It’s close, it’s interesting, and it’s useful. Iwill examineeachattributeinturn,evaluatingitssignificancetothedevelopmentandexplorationofspace.

It’sClose:TheValueoftheMoon’sProximityUnlikemostotherspacedestinations,theMoonisEarth’scompanioninspace.TheEarth-Moon system orbits the Sun as a single planet. Thus, the Moon is alwaysaccessiblefromtheEarth.Thisisinmarkedcontrasttootherdeepspacetargetssuchas planets and asteroids, all of which have independent solar orbits and thus, areoptimallyaccessibleonlyduringcertainshort,periodscalled“launchwindows.”Inthe case of Mars, good launch windows, those requiring the minimal amount ofenergyfor transfer,expressedas“delta-v”orchange invelocity,occurabouteverytwenty-six months. Other targets, such as near Earth asteroids, may have morefrequentwindowsseparatedbymonthsbut lastingonlya fewhours toa fewdays;somehaveevenfewerlaunchwindows.

TheMoonisalwaysavailable.Fiftyyearsago,theApollolauncheswerescheduledwithin very tight launchwindows because the LunarModule had to land on theMoonintheearlymorninghours,whencastshadowsmakethesurfacereliefstandoutclearly.Inthecaseofafuturelunaroutpost,oneofthefirstitemstoemplaceonthe surface will be a beacon, a radio device that allows future landers to landcompletely“blind”at any timeof the lunardayornight.Departures andarrivalswillbeconductedforconvenience,withtimingimposednotbycelestialmechanicsbut by the operational schedules of the flight systems manager. A series of radiobeaconswouldenablethedevelopmentofacompletelyautomatedflightsystem,onethatcouldtransportgoodsandpeoplebetweenEarthandalunaroutpost.

TheMoonisaccessibleviamanydifferentorbitalapproaches(figure6.1).Directpaths, requiring the maximum amount of velocity change (delta-v), are possiblefrom Earth, resulting in transfer times on the order of three days; minimalmodificationpermitslowertotalenergyrequirementsandaddsanotherdayorsototransit time. Staged approaches can be conducted using the L-points or low lunarorbit as a staging location. The advantage of such an approach is that assets andpieces of a complex system can be assembled at a staging node, with the surfacemissionconductedfromthatpoint.TheApollosystemusedlowlunarorbit(100kmcircular) as a staging area. Staging from one of the L-points—usually L-1, about60,000kilometersabovethecenterofthenearsideoftheMoon—hasmanybenefits,including itsutility as amarshaling area for lunar exportswhenwaterproductionmeetsthatlevelandforconstantline-of-sightcommunicationswithbothEarthandMoon.Finally,itispossibletosendlargepayloadsofcargovia“slowboat”transferroutes using efficient, low-thrust, high-energy techniques, such as solar electricpropulsion. These transfers spiral out to lunar distances over periods of weeks tomonths.Butwhile theypass throughtheVanAllenradiationbeltsmultipletimes,theyimposenohazardsbecausetheycarryonlycargoandnotpeople.

Figure6.1.Zonesofcislunarspace.LowEarthorbit(LEO)isthelocationoftheInternationalSpaceStationand

thelimitofmosthumanmissions.Geosynchronousorbit(GEO)isthelocationofcommunicationsandweather

satellites.TheEarth-MoonL-1andL-2pointsarepossiblestaginglocalesfortripstoandfromtheMoon.Low

lunarorbitandthesurfacearewithinthegravitywelloftheMoon.(Credit6.1)

Ifproblemsariseduringlunarjourneys,thereturntoEarthtakesonlyafewdays.Onplanetarymissions,areturntoEarthmaytakemanyweekstomonths,ifpossibleatall.Anabort capability is critical for theplanningofhumanmissions.Thiswasdemonstratedmost dramatically during the flight ofApollo 13 inApril 1970.2AnexplosionofanoxygentankintheServiceModulecrippledthespacecraft’selectricalsystem,makingtheCommandModuleinoperative.BecausetheLunarModulewasstillattachedtothevehicle(theywereontheirwaytotheMoon),thecrewwasableto use it as a “lifeboat” to survive for the three days it took to swing around theMoonandreturntoEarth.Theabilitytoabortaflightinprogress,forsafetyorotheroperationalreasons,distinguishestheMoonfromotherplanetarydestinations.Thisbenefit isanenormousadvantageduring theearly stagesof spacedevelopment,asthereliabilityofnewsystemshasyettobedemonstrated.Catastrophiclossofcrewcan bring a nascent program to a halt, and in some cases, result in its early

termination.Ease of communication with the Earth is another advantage of the Moon’s

proximity.The leverageprovidedby this short time-delay ranges fromthemerelyconvenienttotheoperationallyessential.FortypicalhumanoperationsontheMoonoratlunardistances,round-tripradiotimeisabitunderthreeseconds,anoticeablebuteasilyhandleddelay,aslisteningtoanyoftheApolloaudiofileswillattest.Thecritical value of the short time-delay of lunar distance comes with roboticteleoperation.Aswillbediscussedinmoredetaillater,astrategyforacquiringearlyoperational capability on the Moon will come from the emplacement and use ofroboticassets.Theserobotswillprepareandconstructtheinfrastructureofthelunaroutpost,aswellasbeginworkonresourceharvesting,waterextraction,storage,andprocessing,work that canbeoperated,orat least supervised, remotely fromEarth.Because of the tens-of-minutes time delay for radio propagation, the remoteoperationofmachinesonMarsmakesitdifficulttoaccomplisheventhesimplestoftasks.Incontrast,theproximityoftheMoonpermitsustooperateassetsonthelunarsurfaceinnearrealtime.

The many advantages of the Moon’s closeness make it a logical and usefuldestination in any trans-LEO human spaceflight architecture. The creation ofcapabilityinspacewillbeaccomplishedmoreeasilyandsafelybyfirstlearninghowtooperateinspaceatlunardistances.WithexperienceandcompetenceacquiredontheMoon,wewillbemoreconfidentand skilledwhenwemoveoutward tomoredistantdestinations.ByusingtheMoontolearntheseskillsandtechniques,welearnhowtocrawlbeforeweattempttowalk.

It’sInteresting:TheScientificValueoftheMoonTheMoonoffers scientificvalue that isuniquewithin the familyofobjects in thesolar system.3 It is a recorder of history and process, an ancient world containingmaterials unprocessed since their formationmore than four billion years ago.TheMoon records its own history and the history of the universe around it. Itsenvironment permits unique experiments in the physical and biological sciences.Additionally, it isanatural laboratory forunderstanding theprocesses thatcreatedoursolarsystemandthatcurrentlydrivethegeologicalevolutionoftheplanets.

TheMoonhasundergoneacomplexandprotractedgeologicalhistorythatwecanstudytounderstandearlyplanetaryevolution.FromApollodata,wefoundthattheMoon is a differentiated object, with a metallic core, mantle, and crust. Itssegregation into this tripartite conditionwas the result of globalmelting early in

solar system history. If a body as small as the Moon could undergo globaldifferentiation, it is likely thatall the terrestrialplanetsdid likewise.Thestudyofearlylunargeologichistoryisaguidetotheinterpretationofthehistoryofalltherockyplanets,andtheMoonrecordseventsofanepochforwhichevidencehasbeenerasedfromtheeroded,dynamicsurfaceoftheEarth.Afterthisdifferentiation,theMoon underwent a protracted impact bombardment, hit by objects from themicroscopic to the asteroidal; these collisions formed craters that span similar sizeranges. While we understand the impact process in broad outline, details of thephysicalandcompositionalprocessesremainobscure,especiallyquestionsabouthowthey scalewith size. TheMoon’s abundant craters (figure 6.2), on display for ourstudyandenlightenment,offerinnumerableexamplesofthisprocess.

Figure6.2.Examplesoffreshlunarcraters.RümkerE(38.6°N,302.9°E;7kmdiameter)isasimplecrater,witha

bowl shape and small, flat floor. Large blocks are visible near its rim crest. The complex crater Aristarchus

(23.7°N,312.5°E;40kmdiameter)showswallterraces(fromslumpingaftercraterexcavation),anextensiveflat

floor(impactmeltsheet)andacentralpeak(broughtupfromthedeepcrust).(Credit6.2)

Billionsofyearsago,internalmeltingofthemantleoftheMoonproducedcopiousiron-rich magmas that rose upward to the surface and erupted as vast sheets ofbasalticlava.Theselavasmakeupthelunarmaria,thedarksmoothlowlandsoftheMoon.Theyareconcentratedonthenearside(forreasonsthatstilleludeus)andaremadeupofhundredsof individualflowswithdifferingcompositions,volumesandages. By understanding the sequence of lavas over time, their source regions, andchangesincomposition,wecanreconstructthethermalandcompositionalevolutionofthelunardeepinterior.Again,becausevolcanismisubiquitousontheterrestrialplanets,knowledgeofthelunarexperiencehelpsustobetterunderstandthisprocessacrossthesolarsystem.

The principal geological process on theMoon for the last three billion years isbombardment by a constant micrometeorite “rain” of tiny particles. The flux ofdebrisactsasagiant“sandblaster,”grindingsurfacerocksintoafinepowder.Thislayer of disaggregated rocky debris, the regolith, is exposed to space and thus,implantedwithparticlesfromsourcesexternaltotheMoon.BecausetheMoonhasnoatmosphereorglobalmagnetic field,plasmasand streamsofenergeticparticlesfromtheSun,andtheuniversearoundus,impingedirectlyonitssurface,becomingembeddedontotheselunardustgrains.Thus,theMooncontainsaunique,detailedrecordoftheoutputoftheSunandgalaxythroughgeologicaltime.

Thesolarwindisthemostcommonsourceofparticles,astreamconsistingmostlyof protons that collide with and stick to the lunar dust grains. As this process isconstant, particles from the Sun emitted at varying times in history may berecovered from the ancient regolith andused to reconstruct the output of the Sunand galaxy as itwas in the distant geological past. A special case occurswhen anancient regolith is buried by a lava flow. In this instance, the covered regolithbecomesaclosed-system,shutofffromfurtherparticleimplantation.Thesolarwindgases, preserved in such a closed-system, record a “snapshot” of the ancient Sun,dated by the ages of the bounding rock units above and below the ancientpaleoregolith.

AccessibleregolithsontheMooncoveratimerangeofatleastthelastfourbillionyears. The Sun is the principal driver of Earth’s climate, and by recovering solaroutput over time, a record unavailable anywhere onEarth,we can understand itscyclesandsingulareventsforthedurationofthehistoryofthesolarsystem.Someinitialresults,fromourstudyoftheApollosamples,suggestthattheancientSunhadadifferentcompositionofitsnitrogenisotopesthanitdoesnow,apuzzlingresultnotpredictedbyexistingtheoriesofstellarevolution.WhatothernewandunexpectedsecretsoftheSunandstarslieembeddedontheMoon,awaitingdiscovery?

Becauseof the antiquityof theMoon, and itsproximity to theEarth, the lunarsurfaceretainsarecordoftheimpactbombardmenthistoryofbothbodies.Weknowthat the collision of large bodies has had drastic effects on the geological andbiologicalevolutionof theEarthandoccuratquasi-regular intervals.4Becauseourverysurvivaldependsonourunderstandingthenatureandhistoryofthesecollisionsasabasisforthepredictionoffutureevents,theimpactrecordonthelunarsurfaceiscritical to our understanding of this hazard. By dating a large population ofindividual craters on a surface of known age, we can establish whether theperiodicity of the impact flux is real. Such periodic impactsmay have driven theprocessof evolutiononEarth.These studies coulduncover fundamental,unknownaspectsofthehistoryoflifeonEarthandinthesolarsystem.

Withnoionosphere,andafarsidethatistheonlyknownareainthesolarsystempermanentlyblockingtheradionoiseandstaticofEarth,aradiotelescopeonthefarside of the Moon can examine low frequency wavelengths that are impossible todetect fromEarth’s surfaceor inLEO.The seismicallyquiet lunar surfacepermitsthe construction of extremely sensitive and delicate instruments, such asinterferometers at optical wavelengths. An array of such telescopes could achieveresolutions at the micro-arc second level, allowing the direct observation ofphenomena such as star spots and thehemispheres of terrestrial planets innearbysystems.Suchcapabilitieswouldrevolutionizeourunderstandingoftheevolutionarypathsofstellarandplanetarysystems.

Finally,theenvironmentoftheMoonisitselfascientificassetofgreatvalue.Thehard vacuum and extreme thermal regime permit unique material scienceexperiments. The low gravity of the Moon allows us to quantify the effects offractional gravity on physical and biological phenomena.TheMoon is an isolatedand sterilizing environment, permitting experimentationwithhazardousmaterialsand processes. Facilities on the lunar surface allow us to conduct dangerous orhazardousexperimentsthatwouldbeunwisetopursueontheEarth.Theseuniquepropertiesmake theMoonanunparalleledasset for scientificexperimentationandlaboratorywork.

It’sUseful:TheUtilityoftheMoonWhiletheprevioustwoattributesoftheMoonareextremelyimportant,itsgreatestvalueisitscapacitytocreatenewspacefaringcapabilitythroughtheexploitationofitsmaterialandenergyresources.Theideaofusingthematerialsofotherworldstoprovisionourselves,andtosupplyandsupport spaceflight, isaveryoldone,but to

date, it has not been attempted. Yet, development of this single activity couldcompletelychangetheparadigmofspaceflight.Currently,anythingthatweneedinspacemustbetransportedtoEarthorbitatenormouscost,usuallyontheorderofatleast$1,000–10,000perkilogram.Thishighcostapplies toeverything: It costs thesame amount ofmoney to launch a kilogram of high-technology electronics as itdoes a kilogram of water. If we could provide low-information density materials(likewater,air,androcketpropellant)fromlocalsourcesalreadypresentinspace,wecould accomplish much more for less money. In a nutshell, this is the drivingmotivationfortheuseofoff-planetresources,or,inthetermusedinthebusiness,insitu resource utilization (ISRU).5 This is a skill that we must master in order tobecomeatrulyspacefaringspecies.

Althoughthephysicsandchemistryofextractingandusingtheresourcesof theMoon are simple and straightforward, there has been great resistance toincorporating ISRU into any spaceflight architecture. There aremany reasons forthisattitude,rangingfromunfamiliaritywiththeprocessesinvolvedtoanaturalandatleastpartlyunderstandableconservatisminengineeringdesign.ForinitialISRUefforts,wewouldonlyundertakethesimplestprocesses,suchasbulldozingregolithto make blast berms around landing pads and to cover habitats for radiationshielding,alongwithheatingpolarregolithtoextractwaterice.Theseareminimal,low-riskactivities thatprovideusefulproductsandpiecesofoutpost infrastructure.The techniques needed to begin ISRU are no more complex than everydayeighteenth-centuryindustrialprocesses.

TheresourcesoftheMoonaresimpleandrequireminimalprocessing.First,bulkregolith(soil)hasmanyusesasthermalandradiationshieldingandforconstruction.Although loose soil can be used as is, regolith can also be fused by microwavesintering or passive solar thermal heating (such as a concentrating mirror) intoceramics or aggregate for building material. Roads and landing pads can bemanufacturedbysinteringtheregolithinplaceusingamicrowave-heatingelementmountedonarover.6Microwavesfuselooseregolithintobrickandceramicbecauseofthefine-scale,vapor-depositedfreeironthatcoatsthesurfacesofdustgrains.ThiscoatingpermitsRFenergytobeefficientlycoupledandtransferredintoheat,sothatthegrainboundaries fuse together tomakeglass.Amicrowavewithapower levelcomparabletoakitchenovencanfusetheuppersurfaceintoapavedroadorlandingpad several centimeters deep.Fused regolith structures canbemade as large or aslongasneeded.Structuresandpiecescanbeproducedwith3-Dprintertechnologyusingfineregolithasfeedstock.

TheMoon’spolespossesscriticalresourcesneededforlong-termhumanpresence

ontheMoonandinspace.TheyhavetwokeyattributesthattherestoftheMoondoes not possess: water ice (and other volatile substances) and areas of near-permanent sunlight. We have verified the presence of water ice using severaltechniques of remote sensing, including hydrogen detection, near-infrared andultraviolet reflectance, laser albedo, radar, and a physical impactor. In addition towater—themostcosmicallyabundantvolatilesubstanceinthesolarsystem—othervolatile species are present in the polar ice, including methane (CH4), carbonmonoxide(CO),ammonia(NH3),hydrogensulfide(H2S),andsomesimpleorganicmolecules. All of these volatile substances can be chemically processed to helpsupportahumanpresenceontheMoon.

Questionsremainoverhowmuchwaterandothervolatilesarepresentintotal,ontheirdistributionlaterallyandvertically,andoverwhatphysicalformthedifferentchemicalicestake.ThesevolatilesprobablycomefromsourcesexternaltotheMoon—the impact of water-bearing objects, such as cometary nuclei and volatile-richmeteorites.Assuch,theyaredepositedinextremelysmallamounts,inavacuumandoveraverylongperiod.Thelikelynatureofsuchadepositwouldbeaveryporousmixture of dust grains and amorphous (noncrystalline) ice. In astrophysics, such acompositional fabric is called a fairy-castle structure and is a common state ofmaterialsinspace.

Thedarkareaswhere ice is stableareextremelycold,always less than—169°C(104K),butinsomecasesascoldas—248°C(25K)andwidespreadatbothpoles.Thesedarkareasaretypicallyfoundincraterinteriorsbutinsomecasesasextendedregionsofshadow.The“coldtraps”areallequallylikelytocontainice,butcurrentevidencesuggests,forreasonswedonotfullyunderstand,thattheiceisdistributedheterogeneously (see figure 5.1). In addition, because lunar soil is an excellentthermalinsulator,itispossiblethatextensivedepositsoficemightbepresentintheshallowsubsurface,inareasthatreceivepartialsolarillumination.

We need to survey the potential mining areas to determine their content andgrade. This is best accomplished by using a small robotic rover that traverses thepolarareasandmeasuresicecontentandcompositionovermanylocations.Thedarkareasareclosetothelitregions,asthegrazingsunlightatthepoles,bothilluminatesand shades. Although there are no areas of “permanent” sunlight, certain regionsnearbothpoleshavebeenfoundtobe insunlightformorethan90percentof thelunar year.7 Solar arraysmounted on a highmast could be in sunlight for longerperiods;thispossibilityisasubjectforcurrentresearch.Anoutpostlocatedintheseareas would be able to generate electrical power on a nearly constant basis, withperiodsofdarknessbridgedbypowerstorage,suchastheuseofarechargeablefuel

cell.Another advantage of these “quasi-permanent” sunlit areas is that they are

thermally benign. At the equator of the Moon, the surface is heated during thedaytime,whichis fourteenEarthdays long,reachingtemperaturesofupto100°C.Duringthecoldestpartofthenighttime,alsofourteenEarthdayslong,thesurfacemayassumetemperaturesaslowas—150°C,a250°swingfromthehottestpartoftheday.Thehightemperaturesoflunarnoonputstressonsystemsdesignedtokeepmachinery cool, while the cold night temperatures require moving parts to beheated. Within the sunlit areas near the poles, illumination is always at grazingincidence—that is, the Sun circles around near the horizon—and maintains thesurface temperature at a near-constant—50°C. In such an environment,minimalpower is required tomaintain thermal equilibrium for complexmachinery.Alongwith thepervasivepresence ofhighly abrasivedust that canweardownparts andmakemachineryinoperative,theextremethermalenvironmentisoneofourbiggesttechnical challenges in developing the resources of the lunar poles. Mitigatingstrategiesforeachofthesedifficultiesarecurrentlythesubjectofintensiveresearch.

Inadditiontotheconstantsolarpoweravailableatthepoles,theMooncontainssubstancesthat, inthefuture,maybeusedtogenerateenergyforuseonthelunarsurface and in space. Several regions of the western near side contain elevatedamounts of the radioactive element thorium, which can be used to fuel nuclearreactorstogenerateelectricalpower.Viaseveralnuclearreactions,thoriumbreederreactors can produce their own fuel, making it possible for us to construct spacereactorsontheMoon.Theuseofnuclearpowerwouldallowustosurvivethelonglunar night and permit habitation of equatorial and mid-latitude regions of theMoon.Theavailabilityofabundantpoweralsoenableslarge-scaleindustrializationoftheMoon.

In themore distant future, some have proposed that the rare isotope helium-3,implanted in the lunar regolith by the solarwind, could be harvested to generateelectricalpowerinarelatively“clean”nuclearreaction,onethatdoesnotgenerateexcessneutronsand“dirty”reactionproducts.8Thefusionofdeuterium(hydrogen-2) with helium-3 produces fewer neutrons and positively charged He ions,permittingtheefficientconversiontoelectricalpoweroverthestandarddeuterium-tritium (2H-3H) fusion. In fact, a variant of this process, whereby helium-3 fuseswithitself(3He-3He),producesnoharmfulby-productsatall.Potentially,helium-3fusion could solve the world’s energy problems if a suitably large source of theisotopecouldbefound—itispresentonEarthasacomponentofnaturalgas,butinextremelysmallamounts.

Ithasbeenproposedthatweminethelunarregolithforhelium-3andimporttheproduct back to Earth for commercial electrical power generation. The difficultywiththisideaistwofold.First,wedonotyethavereactorsthatcanburnhelium-3nuclearfusionfuel.Ittakesagreatdealofenergytostartthisreactionandthentocontainandcontrolit;nofusionreactiontodatehasachieved“breakeven,”thepointatwhichthefusionreactionliberatesmoreenergythanittakestostartit.Researchon this problem has been going on for decades; it is unlikely that we will seecommercial applications of fusion power generation for many years. Second,althoughthereishelium-3inthelunarregolith,itispresentinconcentrationsoflessthanabouttwentypartsperbillion.Thislowconcentrationisforsampledsitesinthelunar equatorialmaria; we do not yet know the concentration of helium-3 in thepolarvolatiles.Extractinghelium-3fromthemareregolithwillrequiretheminingand processing of hundreds of millions of tons of regolith, a scale of resourceprocessingthatmayeventuallyoccur,butcertainlynot in theearlystagesof lunarhabitation.Theminingofhelium-3,oftenalludedtoastheultimate“paydirt”ontheMoon,isnotlikelynear-term(~20years)butmayturnouttobesignificantinthemultidecadaltimescalesoffuturelunardevelopment.

Wateristhemostusefulmaterialinspace.Initsnativeform,wecandrinkitanduse it to reconstitute food, cool equipment, and jacket habitats for radiationprotection, as well as for hygiene and sanitation needs. An electrical current candisassociate water into its component hydrogen and oxygen. These gases can bestoredandused;oxygencanbeusedforbreathing,andbothgasescanberecombinedin a fuel cell to generate electricity.Used thisway,water is amedium of energystorage.Finally, thehydrogenandoxygencanbecooledintocryogenic liquidsandused as rocket fuel, themost powerful chemical propellant known. Because of itsutilitarianvalue,wateristrulythe“currency”ofspaceflight.

Thereallunar“ElDorado”consistsofthewatericeandthepermanentsunlightnearthepoles.Itisalocationknowntocontainresourcesofmaterialandenergythatwecanaccessanduse. It isaplacewherewecan learn the skillsand technologiesneededtobecomepermanentresidentsofspace.

WhyNotMars?Virtually the entire space community, from those inside the agency to othersworkingonspacecraft,missionsordataanalysis,presumethatMarsisthe“ultimategoal”forhumanspaceflight.9In1965,theimaginativepullthatdecadesofsciencefictionandspeculationaboutMarsasanEarthlikeplanethaddealtusweredashed

when we found by direct investigation that the real Mars is a distant, cold, drydesert,withvirtuallynoatmosphere.Subsequentmissionsovertheyearshaveshownthat itmay have beenwarmer andwetter in the past,which led to the idea thatmicrobiallifemighthaveoriginatedthere.ThissingleideaislargelyresponsibleforthesubsequentfixationonMarsasthe“nextdestination”forhumansinspace.Theobsessionwith “searching for life elsewhere” has hijacked our thinking about thefuture of people in space. It is virtually impossible to advance an idea or conceptinvolvingpeopleatsomespacedestinationotherthanMars,withoutprovingthatit“feedsforward”toour“ultimatedestination.”

WedonotknowhowtosendpeopletoMarsatthistime.Thedifficultieswithahuman mission to Mars fall into several categories: technical, programmatic, andfiscal.Themanned spaceprogramhasconducted long-duration spaceflight,builtaheavy-liftlaunchvehicle,andconductedlandingsontheMoon.Butforavarietyofreasons,gettinghumanstoMarsismuchmoredifficult.MarsismuchfartherawayfromEarth,varyingbetween140to1,000times(55to400millionkm)thedistanceofEarthtotheMoon(400,000km).Noknowntrajectorycanshortenthemonthsoftransit; most robotic missions take nine months. Although issues of crewdeconditioning caused by microgravity appear to be mostly resolved from flightexperience on the ISS, months of exposure to hard cosmic radiation and theoccasionalpossiblesolarparticleevent,requiressometypeofshielding.Peopleneedtobreathe,eat,anddrink,sothoseconsumablesmustbecarriedwiththem.MarsisbiggerthantheMoon(itsgravityisabout3/8thatoftheEarth,comparedtothe1/6goftheMoon);thus,itrequiresmoreenergytodescendandlandonthesurfaceofMars.Thisappliestothereturntripaswell.ThelargergravitywellofMarsmeansthatbigger landersandmorefuelareneeded.Althoughthere isanatmosphereonMars, it ismore than one hundred times thinner than Earth’s, so we cannot relysolely on aerothermal entry to slow down the spacecraft; a significant propulsivemaneuverisrequired.Thisissue,theEDL(entry,descent,landing)problem,10isoneforwhichwehavenosolutionatpresent.

Thecompositionofthemartianatmosphereisvirtuallypurecarbondioxide(CO2)and thus, not breathable; the thinness of the atmosphere requires people to wearpressuresuits.ThesurfaceisnotcompletelyshieldedfromcosmicraysandsolarUVradiation;MarsdoesnothaveamagnetosphereliketheEarth,whichmeansthatitisahardradiationenvironment,limitingthepermissibletimeforsurfaceexploration.ThesoilonMarsisveryfine,probablyconsistingofclayminerals,andowingtothepresence of perchlorates and other highly oxidizing substances, it appears to behighly reactive chemically. If inhaled—and some dust inevitably will be brought

intothecrewcabin—dustcouldresultincausticchemicalreactionsinthebronchiaofthecrew’slungs.Inaddition,nooneknowshowwellhumanswillcopewiththereduced gravity of the martian surface after spending multiple months inmicrogravity.

ThebiggestproblemwithahumanMarsmissioncomesrightatthebeginning.Inordertocarrythefuel,consumables,equipment,andvehiclesthatthecrewwillneedforthistrip,itwillrequirethelaunchofbetween500and1,000metrictonsintolowEarthorbit.11Gettingthismassintoorbitwillrequireeighttotwelvelaunchesofaheavyliftrocket,eachcarryingabout130metrictonstospace.Thevastbulkofthismassisthefuelrequiredforthetrip,mostofwhichisburnedatthebeginningofthevoyagetoinsertthevehicleintoitsplanetarytrajectory.Butthat’snottheendoftheissue.Thefuelwillprobablybecryogenichydrogenandoxygen; ifweusestorablepropellant,multiplythemassneededbyfactorsoftwotothree.Afteritisdeliveredto orbit to await the eventualmission toMars, the super cold cryogenic fuel willquicklyboilofffromsolarheating.Itwouldbearaceagainsttheclocktogetenoughfuel in one place in orbit at the right time. For now,we have no solution to theproblemof fuel boiling off in the landers, both for descent and ascent, during thecruisephaseofamannedmissiontoMars.

Other problems arise in terms of the scheduling of themultipleHLV launchesand coordinating their payload manifests. Only two HLV launch pads (LaunchComplex 39) exist at Cape Canaveral. One is currently unavailable, leased to aprivatecompany.Thus,wewouldneedtolaunchallofthesevehiclesfromasinglepad.TogetthepiecesoftheMarsmissioninoneplaceandreadytogo,wemustdealwith an enormous scheduling and manifest problem, as well as the logistics ofmultiple HLV deliveries. After that, the next hurdle would be assembling andfuelingtheMarsvehicleinspace.

ThecostofaMarsmissionconductedinthismannerisestimatedatseveraltensof billions of dollars per trip. Is such a cost politically viable? Regardless of thepropagandaspunbyahopefulNewSpacecommunity,therearenomagicbulletstolowerthisenormouscost.WestillneedthesamemassinLEO,andthe“lowering”oflaunchcosts,whichinanyeventisonlyontheorderoffactorsoftwoorthreeatbest,mightturna$500billionmissionintoa$450billionmission.Forcontext,wecurrentlyspendabout$18billionperyearonourcivilspaceprogram,ofwhichabout$8billionisdesignatedforhumanspaceflight.

Facedwiththeserealities, itshouldbeevidentthatMarsisveryfarfromEarth,technicallyandfiscally.ButthehardwireddreamsoflivingonMarshaveleftspaceadvocates of all persuasions chasing their tails, locked in a 50-year exercise by the

promisesofpoliticiansoradministratorswhotellus,“Yes,wewillbeembarkingonanewprogramtosendhumanstoMars.”Whatfollows,asnightfollowsday,isthatpeople get spun up and start conducting feasibility studies; new vehicles aredesigned,andlovelycolorartworkshowingpeoplerappellingdownthewallsofoneof the canyons of Valles Marineris is produced. And then, yet again, the dismalmathematicsofaMarsmissionbecomesevident.But,wearetold,nottoworry:Themissionisatleastacoupleofdecadesintothefuture.Somehow,themoneyandthepolitical support for more money still will magically appear at the right time.Certainly,ifwecanassembleaMarsadvocacygroup,onethatshowswehavecloutandthatstrikesfearintheheartsofourelectedofficials,wewillgetmoremoney.Todate, thesemethods and declarations have accomplished nothing. But, our leaderstellus,thiswillchangeassoonaswefindawaytogetthepublicexcitedaboutspace—that“excitement”causesmoneytoflowintothespaceprogram.After50years,isitnottimetoadmitthatthisapproachisn’tworking?

An article of faith among the true believers is that interest in the Moon andplanning for lunar bases has kept them from achieving their lifelong dream ofstrolling across the red plains ofMars.The reality is exactly the reverse: It is thefixation with sending people to Mars that has kept us from doing any humanmissions beyond LEO. Looking over the history of post-Apollo planning, fromNixon’sSpaceTaskGroup in1969to theVisionforSpaceExploration in2004,allefforts togetpeople into trans-LEOspacehaverunagroundontherealitiesof theenormoustechnicalandcostdifficultiesofhumanMarsmissions.12DuringtheVSE,NASAwasmore concernedwithdevisinga lunar“exit strategy” than itwaswithgetting people back to theMoon in the first place.13The dirty little secret is thatmost politicians love human Mars missions not because they have any desire orinterest indoing them but because it is an excellent and provenway to keep thespacecommunitypacifiedbyselectingagoalthatissofarintothefuturethatnoonewill be held accountable for its continuing non-achievement. What a remarkableaccomplishment for America’s efforts in space: oncewe had a real space programthat some thoughtwas faked, and nowwe have a fake space program thatmanybelieveisreal.

The onlywaywewill ever get people toMars is through the construction of atransportation system that enables the routine movement of cargo and peoplethroughoutspace.AnApollo-stylecrashprogramtosendhumanstoMarsishighlyunlikelytoevermaterialize.Weneedtoacquireandlearncertainspacefaringskillsand technologies, including reusable space-based vehicles, staging nodes in deepspace,insituresourceutilization,andthemanufactureofpropellantfromwater.If

we possessed these capabilities, a humanmission toMars, while still challenging,would become more feasible. We can learn those skills and acquire thosetechnologiesontheMoon.

WhynotMars?Becauseit’stoofar,toodifficult,andtooexpensive.

WhyNotAsteroids?At first glance, it might seem that asteroids, specifically the near-Earth objects(NEO), answer the requirements for future humandestinations.NEOs are beyondlow Earth orbit, they require long transit times and so simulate the duration offutureMarsmissions,andwehavenevervisitedonewithpeople.However,detailedconsiderationindicatesthatNEOsarenotthebestchoiceasournextdestinationinspace.

MostasteroidsresidenotneartheEarthbutintheasteroidbelt,azonebetweenthe orbits of Mars and Jupiter. The very strong gravity field of Jupiter willsometimesperturbtheorbitsoftheserockybodiesandhurlthemintotheinnersolarsystem,where theyusuallyhit theSunoroneof the innerplanets.Between thosetwoevents, theyorbit theSun,sometimescomingclose to theEarth.NEOscanbeanyofavarietyofdifferenttypesofasteroids,butareusuallysmall,ontheorderoftens of meters to a few kilometers in size. As such, they do not have significantgravityfieldsoftheirown,somissionstothemdonot“land”onanalienworld,butratherrendezvousandstation-keepwiththemindeepspace.

Themoniker“nearEarth”isarelativedescriptor.TheseobjectsorbittheSunjustastheEarthdoes,anddependinguponthetimeofyear,varyindistancetotheEarthfromafewmillionkilometerstohundredsofmillionsofkilometers.GettingtooneNEOhasnothing to dowithgetting to another, so visitingmultipleNEOsduringonetripisbothdifficultandunlikely.BecausethedistancetoaNEOvarieswidely,wecannotjustgotoonewheneverwechoose:Launchwindowsopenatcertaintimesof the year, and because the NEO is in its own orbit, these windows occurinfrequentlyandareofveryshortduration,usuallyafewdays.Moreover,duetothedistances between Earth and the NEO, radio communications will not beinstantaneous,withvaryingtimelagsoftensofsecondstoseveralminutesbetweentransmissionandreception.

AlthoughthereareseveralthousandNEOs,fewofthemarepotentialdestinationsforhumanmissions.Thisisaconsequenceoftwofactors.Becausespaceisverybig,evenseveralthousandrocksspreadoutoverseveralbillioncubickilometersofemptyspace results in a very low density of objects. Second, many of these objects are

unreachable,requiringtoomuchvelocitychangefromanEarthdeparturestage;thiscanbetheresultofeithertoohighofanorbitalinclination(outoftheplaneoftheEarth’s orbit) or an orbit that is too eccentric (to varying degrees, all orbits areelliptical). These factors result in reducing the field of possible destinations fromthousandstoadozenorso,atbest.

Therearefewasteroidtargetsandittakesmonthstoreachone.Longtransittimeissoldasabenefitbyadvocatesofasteroidmissions:BecauseatriptoMarswilltakemonths,aNEOmissionwillallowustotestoutthesystemsforMarsmissions.Butsuchsystemsdonotyetexist.OnahumanmissiontoaNEO,thecrewisbeyondhelpfromEarth, except for radioed instructions and sympathy.AhumanNEOmissionwill have to be self-sufficient to a degree not present on existing spacecraft. Crewexposure to the radiation environment of interplanetary space is anotherconsequenceoflongflighttimes.Thishazardcomesintwovarieties:solarflaresandgalacticcosmicrays.Solarflaresaremassiveeruptionsofhigh-energyparticlesfromtheSun,occurringatirregular,unpredictableintervals.Wemustcarrysometypeofhigh-massshieldingtoprotectthecrewfromthisdeadlyradiation,andthis“stormshelter”mustbecarriedwhereverwego.BecauseApollomissionswereonlyafewdays long, the crew simply accepted the risk of possible death from a solar flare.Cosmic rays are much less intense, but constant. The normal ones are relativelyharmless,buthigh-energyversions(heavynucleiexpelledfromancientsupernovae)cancauseserioustissuedamage.Althoughthecrewcanbepartlyshieldedfromthishazard,theyarenevertotallyprotectedfromit.

Whenthecrewfinallyarrivesattheirdestination,moredifficultiesawait.ManyNEOsspinveryrapidly,withrotationperiodsontheorderofa fewhoursatmost.Thismeans that the object is approachable onlynear its polar area.Because theserocksareirregularlyshaped,rotationisnotthesmooth,regularspinofaplanet,butismore likethatofawobblingtoytop.Ifmaterial isdisturbedonthesurface, therapid spin of the asteroid will launch this debris into space, creating a possiblecollision hazard to the human vehicle and crew. The lack of gravity means that“walking”onthesurfaceoftheasteroidisnotpossible;crewwill“float”abovethesurface of the object, and just as occurs in Earth orbit, each touch of the asteroidsurface (action) will result in a propulsive maneuver away from the surface(reaction).

Wewouldneedtoworkquicklyattheasteroidbecausewewouldnothavemuchtimethere;loitertimesneartheasteroidformostopportunitiesareafewdays.Whyso short?Because the crewwants to comehome.TheNEOandEarth continue toorbittheSun,andweneedtomakesurethattheEarthisintherightplacewhenwe

arrivebackatitsorbitalposition.Ineffect,wewillspendmonthstravelingthereinavehiclewiththehabitablevolumeofalargewalk-incloset,haveashorttimeatthedestination,andthenspendmonthsonthetriphome.

Ingeneralterms,wealreadyknowwhatasteroidsaremadeof,howtheyareputtogether, and what processes operate upon their surfaces. Most NEOs will beordinary chondrites.Weknow this because ordinary chondritesmakeup about 85percentofallobservedmeteoritefalls.Thisclassofmeteoriteisremarkablenotforitsdiversity,butforitsuniformity.Chondritesareusedasachemicalstandardintheanalysis of planetary rocks and soils tomeasure the amounts of differentiation orchemicalchangeduringgeologicalprocessing.Onechondriteisprettymuchlikealltheothers.

Questions that could be addressed by human visitors to asteroids concern theirinternal makeup and structure. Some appear to be rubble piles, while others arenearly solid. Why such different fates in different asteroids? By using activeseismometry (acoustic sounding), a human crew could lay out instruments andsensors to decipher the density profile of an asteroid. Understanding the internalstructure of an asteroid is important for learning the internal strength of suchobjects;thisisanimportantfactorindevisingstrategiestodivertaNEOawayfromacollisioncoursewithEarth.

Anallegedbenefitof travel toanasteroid is that theyhaveresourcepotential. Iagree,putting theaccenton theword“potential.”Ourbestguide to thenatureofthese resources comes from the study of meteorites—NEOs that have alreadycollidedwiththeEarth.Theresourcepotentialofasteroidsliesnotinthechondrites,butintheminorityofasteroidsthathavemoreexoticcompositions.Metalasteroidsmakeupabout7percentof thepopulationandare composedofnearlypure iron-nickelmetal,withsomeinclusionsofrocklikematerialasaminorcomponent.Othersiderophile (iron-loving) elements, including platinum and gold, make up traceportions of these bodies. Ametal asteroid is an extremely high-grade ore deposit,potentially worth billions of dollars, if we were able to get these metals back toEarth.

However,fromthespaceflightperspective,waterhasthemostvalue.Arelativelyrareasteroidtypecontainscarbonandorganiccompounds,aswellasclaysandotherhydrated minerals. These bodies contain significant amounts of water (up to 20weight percent). Finding a water-rich NEO would create a logistics depot ofimmensepotentialvalue.

A key advantage of asteroids as a resource is a drawback as an operationalenvironment:Theyhaveextremelylowsurfacegravity.Gettingintoandoutofthe

Moon’sgravitywellrequiresachangeinvelocityofabout2,380meterspersecondeachway;todothesameforatypicalasteroidrequiresonlyafewmeterspersecond.Thismeans that a payload launched froman asteroid rather than theMoon savesalmost5kilometerspersecondindelta-v,asubstantialamountofenergy.Fromtheperspective of energy accessibility, the asteroids beat the Moon as a source ofmaterials.

Yetthereremainsthechallengeofworkinginverylowgravity,aswellasotherdifficultiesthatexistinminingandusingasteroidal,asopposedtolunar,resources.First is thenatureofthefeedstockor“ore.”WateratthepolesoftheMoonisnotonlypresentinenormousquantity,tensofbillionsoftons,butisalsoinaformthatcanbe easilyused: ice. Ice canbe converted into a liquid for furtherprocessingatminimalenergycost;iftheicyregolithfromthepolesisheatedtoabove0°C,theicewillmeltandwatercanbecollectedandstored.Thewaterincarbonaceousasteroidsis chemically bound in mineral structures. Significant amounts of energy arerequiredtobreakthesechemicalbondstofreethewater,atleasttwoorthreeordersofmagnitudemoreenergythantomeltice,dependingonthespecificmineralphasebeingprocessed.Soextractingwaterfromanasteroid(presentinquantitiesofafewpercenttomaybeacoupleoftensofpercent)requiressignificantenergy;watericeatthepolesoftheMoonispresentingreaterabundance(upto100percentincertainpolarcraters)andisalreadyinaformthatiseasytoprocessanduse.

The processing of natural materials to extract water has many steps, from theacquisitionofthefeedstock,tomovingthematerialthroughtheprocessingstream,to the collection and storage of the derived product. At each stage, we typicallyseparateonecomponentfromanother;gravityservesthispurposeinmostindustrialprocessing.Achallengetoasteroidresourceprocessingistodevisetechniquesthatdonotrequiregravity,includingrelatedphenomena,suchasthermalconvection,ortocreateanartificialgravity field to ensure that thingsmove in the rightdirections.Eitherapproachsignificantlycomplicatestheresourceextractionprocess.

ThegreatdistancefromtheEarthandpooraccessibilityofasteroidscomparedtotheMoonworksagainst resourceextractionandprocessing.Humanvisits toNEOswillbeofshortduration,andbecauseradiotimelagstoasteroidsareontheorderofminutes,directremotecontrolofprocessingwillnotbepossible.Roboticsystemsforasteroidminingmust be designed to have a large degree of autonomy. Thismaybecomepossiblebutpresentlywedonothaveenoughinformationonthenatureofasteroidal feedstock todesign,orevenenvision, theuseof suchroboticequipment.Moreover, even if we did fully understand the nature of the deposit,mining andprocessing are highly interactive activities on Earth and will be so in space. The

slightestanomalyormiscalculationcancausetheentireprocessingstreamtobreakdown, and in remote operations, it will be difficult to diagnose and correct theproblemandrestartit.

The accessibility issue also cuts against asteroidal resources.We cannot go to agiven asteroid atwill; launchwindows open for very short periods and are closedmostofthetime.Thisaffectsnotonlyouraccesstotheasteroidbutalsoshortenstheperiodswhenwemaydepart from theobject to returnourproducts tonear-Earthspace.Incontrast,wecangotoandfromtheMoonatanytime,and itsproximitymeans that nearly instantaneous remote control and response are possible. Thedifficultiesofremotecontrolforasteroidactivitieshaveledsometosuggestthatwedeviseawayto“tow”thebodyintoEarthorbit,whereitmaybedisaggregatedandprocessed at our leisure. I shudder to think about being assigned to write theenvironmentalimpact(ifyou’llpardontheexpression)statementforthatactivity.

Sowhere does that leave us in relation to space resource access and utilization?Asteroidresourceutilizationhaspotential,butgiventoday’stechnologylevels,ithasuncertainprospectsforsuccess.Asteroidsarehardtogetto,haveshortvisittimesforround-trips,difficultworkenvironments,anduncertainproductyields.Asteroidsdohave lowgravitygoingfor them,which isbothablessingandacurse.Incontrast,theMoonhas thematerialswewant and in the form thatweneed.TheMoon isclose and easily accessible at any time and is amenable to remote operationscontrolledfromEarth,innear-realtime.WeshouldgototheMoonfirsttolearnthetechniques,difficulties,andtechnologytoconductplanetaryresourceutilizationbymanufacturingpropellantfromlunarwater.Nearlyeverystepofthisactivity,fromprospecting and processing to harvesting, will teach us how to mine and processmaterials from future destinations, on both minor and planetary-sized bodies.LearninghowtoaccessandprocessresourcesontheMoonisaskillthattransferstoanyfuturespacedestination.

TheMoon:OurNextDestinationinSpaceThe Moon is the first extraterrestrial object after leaving Earth orbit and it is ahighlydesirableplacetovisitandutilize.Whywouldwenotwanttoexploreanduseit?Yet,aswehaveseen,twopresidentialattemptstoreturntotheMooninthepasttwenty-fiveyearshavebothendedinfailure,stifledbybureaucraticprocessandthecontinuingsirencallofMars.OthernationsclearlyseethevalueoftheMoon.Whycan’twe?

Inpart,America is thevictimof itsownearlysuccessontheMoon.TheApollo

missions and the associated robotic missions that preceded them, were greattechnicalandemotionaltriumphs.Theyproducedsightsandexperiencesthathaveyettobesurpassed,evenbythetechnicallymorechallenging(butalsomoreprosaic)flightsofthespaceshuttleandtheconstructionoftheISS.Itwetourappetitesformore.BecauseofApollo,thereisasensethatwe’vebeenthere,andoverlyanxiousexplorersdon’tseeareasontoreturn.ThisignoranceandquickdismissalaboutwhattheMoonhas to offer is exploited by space advocateswhohave other agendas: toquestforlife,tostepontonewworlds,tobuildcoloniesandtransformotherplanets.Noneofthosemotivationsbythemselveshavehadanybettersuccessingeneratingmore—or even adequate—funding for the civil space program. In particular, theconstant and recurring obsession with human missions to Mars has kept us frompursuing the more valuable and emphatically achievable near-term goal: apermanentreturntotheMoon.

Simply put, most people are indifferent to space. This has been true since thebeginningofspaceflight,evenduringtheApolloprogram.14Theyareneitheroverlyenthusiasticnorhostiletoit;theyareatbest,mildlyinterestedinspace,occasionallybecoming enthusiastic and patriotic in times of significant accomplishment. Foryears,spaceadvocateshavehadtheobsessivecertaintythatiftheycanimparttothepublic the same zeal that they feel for Mars or space colonies, or whatever theircause,thattheywillbeshoweredwithmoremoney,forever.Thathasn’thappenedanditwon’t.Atbest,therewillbeamodestlevelofongoingfederalfunding—moreorlesswhatNASAhasreceivedsincetheendoftheApolloprogram.

We must craft a program that will endure for decades, a program that makessteady, constant progress and returns tangible benefits with the levels of fundinglikelytobemadeavailable.Ourchallengeistoworkwithwhatwehave.Yet,howcanwe craft a program that aims for big goals, like space settlement or planetarymissions, under existing constrained budgets? I have spent the last few yearsexploringthatquestion,andIbelievethereisaclearpathforward.

A

7How?ThingsWeShouldHaveBeenDoing

lthough several attempts to revitalize lunar exploration met with partialsuccess,currently,theMoonisnotastrategicdestinationfortheUnitedStates.

A generalmisunderstanding of the value of theMoon keeps stalling our plans toreturn.TheApolloprogramwasa successful architecture forgettingpeople to theMoonandthatseminalexperiencestillcolorsmanyviewpointsonhowtoapproachalunarreturn.TheApolloprogramwastheproductofhistoricalcircumstancesbornduringaspecifictimeandplace.Whilethatexperienceholdsmanylessonsforus,wemustresistusingitasaguidebooktogetbacktotheMoon.

QuestionsonhowtoextendhumanreachbeyondLEOhavepreoccupiedthespacecommunityforyears,withwidelyvaryingopinionsontheappropriatestepstotake,theorderinwhichtotakethem,andhowtoimplementthespecifictechnicalneedsofeachphaseofhumantravelindeepspace.Althoughmanyofthesechoicesareamatterofpersonalpreference,thereisacommonsetofrequirementsthatanytrans-LEO architecture must satisfy. In what follows, I will outline some of the basicchallenges of human spaceflight, the specific issues confronting travelers beyondLEO,andhowtheseissuescanbeaddressed.1

SomeSpaceflightBasicsRocketenginesworkthroughcombustion.Thechemicalenergystoredinpropellantisreleasedandexpelledthroughanozzleathighvelocity.Wehavemanychoices—the type of fuel and oxidizer, the engine configuration, fuel flow rates and thegeometry of the combustion chamber, aswell as themixing ratios and the nozzlediameter to vary the amounts of power a given rocket engine can generate.Regardless of how we might vary these parameters, we remain fundamentallylimitedinwhatwecanputintospacefromthesurfaceoftheEarth.

The principal limiting factors in spaceflight are the force of gravity and theamountofenergyavailableforreleaseinthechemicalbondsofthepropellant.Wecandonothingabouteitherofthesetwofactors;theyaredictatedbynature.Atbest,we can be clever in our engineering by employing strategies like staging, and byvaryingthetypesofmaterialsusedtomakestructures.Butvaryingtheseparameters

work only at the margins, not at the fundamentals. Those fundamentals aredescribedby somethingcalled the rocketequation, first formulated in1903by theRussian“FatherofAstronautics,”KonstantinEduardovichTsiolkovsky.Therocketequationessentiallysaysthatforchemicalfuels,arocketmustconsistofabout80–99percentpropellantbymass.Thisdepressingarithmeticinformsusthatthepayload—theusefulmassthatwewanttogetintospace—canbeonlyasmallfractionofthemassofthevehicle.2

Thissimplefactoflife,onethatastronautDonPettitaptlyterms“thetyrannyofthe rocket equation,” means that going into space is possible, but difficult andexpensive.3Typicalcommercial launchvehicles (CLV)areable toput2–30metrictons of payload into low Earth orbit, at a cost of between $30 million and $500millionperlaunch.Thesecostsmustincludethenecessaryinfrastructurecosts,suchasgroundsupport, tracking,andinsurance.All theair,water, food,andequipmentthecrewneedsduringthemissionmustbebroughtupbylaunch.Thismanifestisinaddition to the mass of the launch vehicle, including its structure, tankage, andavionics.

Toachieveorbit,apayloadmustbelaunchedalongacarefullychosentrajectorywitha rocketburnofprecisemagnitudeandduration. Itmustbe liftedabove theatmospheresothataerodynamicdragdoesnotslowthepayloaddowntoroughly100kilometersabovetheEarth,apointcalledtheKarmanline, theboundarybetweenairandspace.4Itmustbeacceleratedtoavelocityofabout7.8kilometerspersecond;at this speed, thedistancetraveledbythevehicleperunit timeisgreater thanthemagnitude of the curvature of the Earth. When this condition is achieved, thelaunchedobjectwillconstantlycircletheEarth—itisinorbit.AtthealtitudesoflowEarthorbit(~200–300km),tracesofatmosphereoccur,meaningthatanorbitwilleventually deteriorate over time. Because of atmospheric drag, a satellite in LEOeventually will reenter the atmosphere. To alleviate this problem, satellites carrysmallamountsoffuelthatareburnedinsmallrockets,thrustersfiredincontrolledbursts,tomaintainitsorbit.

TogobeyondLEOtohighgeosynchronousorbit(36,000kilometersaboveEarth),anL-point, or to theMoonorplanets (see figure6.1), additionalvelocity (positivedelta-v)mustbeimpartedtothespacecraftbyarocketburninthecurrentdirectionof travel. An engine burn requires propellant, but existing launch vehicles reachLEOwithemptyfueltanks.Theonlywayaroundthisproblemistoincludethefuelneeded for trans-LEO travel as part of the payload, which further reduces theremaining fraction available for useful payload, or refuel the upper stage from astored supply already in LEO. The first method requires the development of

somethingcalledaheavy-lift launchvehicle (HLV).Sucha rocket’s specific size isnotrigorouslydefined,buttypically,anHLVisabletoput50to100metrictonsormore intoLEO.An example of anHLV is the SaturnV of theApollo era,whichcouldlaunch116metrictonsintospace.TheSaturnVwasthebiggestlaunchvehiclethe United States ever built and was sized specifically for the requirements of ahumanmissiontotheMoon,whichincludedtheSaturnIV-Bupperstage,theLunarand Command-Service Modules, and the liquid hydrogen-oxygen fuel needed tosendtheentirestructuretotheMoon.

ThealternativetechniquefortravelbeyondLEOistostorepropellantatadepotin space, then refuel thedeparture stage from that source.5The ideaofpropellantdepots in low Earth orbit has drawn a lot of attention, especially from manyarmchairengineerswhohaveneveractuallyflownamissionbeyondLEO.Althoughthissoundslikeagoodidea—indeed,itisaspacefaringskillthatwemusteventuallymaster—thehiddenassumptionofthedepotconceptisthatwepossessthecapabilityto launch the propellant “cheaply” from Earth, usually via some magicallyinexpensive“commercial”source,andstoreitinorbit.Thisisasimplifiedaccountofthe depot concept; many other complex variables must be considered such aspropellantboil-off, transfer techniques,managementof thearrivalsanddeparturesof the tankers, and manifesting the facilities and timings of each launch ofpropellant cargo. Propellant depots are something that we eventually will takeadvantage of, particularlywhenwe are ready to export propellant from the lunarsurface.Forthemoment,theuseofdepotsisinvokedprimarilyasasubstituteforaheavy lift launch vehicle. In the future, once we begin to produce and exportpropellant from the Moon, depots will be essential for supplying the vehicles ofcislunarandplanetaryspaceflight.

A benefit Earth provides is that we can decelerate returning spacecraft usingatmospheric friction dissipated as heat for braking, thus eliminating the need forpropellant to slow down a returning spacecraft, thus making practical spaceflightpossible. All returning human missions to date have used this technique, calledaerothermalentry.Avariantofthisconceptisaerobraking,inwhichavehicledoesnot actually land, but uses the atmosphere to slow down enough to enter orbitaroundaplanet.Althoughnotusedyetonhumanmissions,thisapproachhasbeenusedonsomeroboticspacecraft sent toorbitVenusandMars.6Aspartofasystemthatcanbereusedandexpanded,aerobrakingisanotherskillthatmustbemasteredinordertodevelopapermanentspacetransportationsystem.

TherocketequationdictatesthatwhiletraveltoLEOisdifficult,travelbeyonditbecomesincreasinglymoreso.Althoughtheactualnumbersvarydependingonthe

propulsion system and its fuel, putting a single kilogram in lunar orbit requiresaboutfivekilogramsinLEO,while landingasinglekilogramonthelunarsurfacerequiresaboutsevenkilogramsinLEO,mostofwhichispropellant.Asystemthatenables routine access to cislunar space—the volume of space between Earth andMoon,includingthelunarsurface—couldbeestablishedbysettingupstagingareaswheretheintermediatetravelsegmentstothevaryinglevelsofcislunarspacemightbelaunched.ExamplesofsuchstagingareasincludeLEO—theISSisonepossibility;GEO, a useful location to access communications and weather satellites; theLagrangian(libration)points,ofwhichL-1andL-2areoftenmentioned;andlunarorbit,withavarietyofpossibilities.Attheselocations,differentspacecraftandpiecesmaybeassembled to travel to thenext location; theywouldalsobe locales for theestablishment of propellant depots. A network of transportation nodeswill enableconstantandroutineflightthroughoutcislunarspace.

The tyranny of the rocket equation makes spaceflight difficult, and thereforeexpensive.It ispossibletosavesomemoneybyusingcleverengineeringandsomespecializedtricks,buttypically,suchapproachesonlynibblearoundthemarginsanddonot take big bites out of the core cost.This reality—the limiting arithmetic ofspaceflight—cannot be addressed with finality as long as we haul everything weneedupfromthebottomofthedeepestgravitywellintheinnersolarsystem.Wewill break loose from our tether oncewe learn how to create new capabilities byprovisioningourselvesfromwhatwefindinspace.

LaunchVehicleOptionsAfter thirtyyearsof service, the space shuttlewas retired in2011.Manyobserversregardedtheshuttleasunsafeandinefficient,butalthoughfourteenpeoplediedintwovehiclefailures,341peoplesafelymadethetriptoandfromLEO,sometakingmultiplevoyages.Moreover,thefailureoftwoflights,ChallengerandColumbia,outofatotalof135flights,givesthespaceshuttlea98.5percentsuccessrate,oneofthebestinthehistoryofspaceflight.Nooneconsidersthelossofhumanlife,eventhosewhochoose tochallenge the limits,asanythingbut tragic,buteach lossofvehicleandcrewledtosafersubsequentflights.Attheendoftheprogram,theshuttlewasoperatingaboutassafelyasanyEarth-to-LEOtransportationsystemcould.

Anenduringproblemwiththeshuttlesystemwastheamountoftimeandeffortneededtorefurbishitaftereachflight.Oftheshuttlestack,onlytheexternaltankwas discarded; all other pieceswere recovered and reused. The solid rocketmotorsegmentsweresimplyrefilledwithpropellant.However,theorbiterrequiredmany

man-hoursofworktoprepareforlaunch,especiallythesilicatilesusedtoprotectthevehicle during the searing heat of reentry. Copious labor-intensive work on thethermal protection system vacuumed up money (during its years of operation,shuttleoperationstookupthemajorfractionofthehumanspaceflightbudget).Forthisreason,somecriticsconsidertheshuttleapolicyfailure,inthatitdidnotmakespaceflighttoandfromLEO“cheap,”eventhoughthatwasneveroneofitsdesigngoals.7However,abetterwaytolookattheshuttleisthatitsgoalasavehiclewastomakespaceflight“routine”—anditdid.Moreover,thesizeanddesignoftheshuttlegaveitsomeuniquecapabilities,somenotavailableonanyplannedfutureAmericanspacecraft.

Nowthatthespaceshuttleisahistoricalrelic,weareessentiallyinthebeginningdays of a new human spaceflight system. Currently under development are theremnants of Project Constellation: the Orion spacecraft and the Space LaunchSystem (SLS).8 Orion can be configured to carry up to six passengers, four forcislunarflights,andhasthecapabilitytoresideinspaceforaboutthreeweeks.Thisduration is adequate for almost all cislunarmissions, but formissions beyond theMoonto,say,Marsoranasteroid,Orionwillneedadditionalmodulesforhabitation,planetarylanding,andotherfunctions.Inessence,Orionisonlyasinglepieceofatrans-LEOspacecraftsystem.Moreover,thedesignoftheOrioncommandmoduleisnotconducivetosatelliteservicing,landingonaplanetaryobjectorextensiveEVA;since it has no airlock, the entire spacecraft must be depressurized beforecrewmemberscanegress.

The new rocket under development is a heavy lift vehicle (HLV), the SpaceLaunchSystem(SLS).TheSLSisbuiltwithpiecesderivedfromtheretiredshuttlesystem, including its engines (modified shuttle main engines, burning LOX-hydrogenfuel),itssolidrocketmotors,anditscentralcoretankage.Initsbasicform,the SLS can put about 70 metric tons into LEO; there are plans to increase thatcapacity, first to about 100 tons and ultimately to 130 tons. Depending upon thearchitecture, this core70 tonpayloadcapacity is adequate formost lunarmissions.ThelargestvariantoftheSLSisscaledforhumanMarsmissionsstagedcompletelyfromEarth.Insuchacase,eighttotwelveseparatelaunchesareneededtoassemblethe500+tonMarsspacecraftinEarthorbit.

The principal advantage of an HLV is that the number of launches needed toconduct a mission is minimized. Each launch has a finite probability for failure,which is multiplied by the total number of launches. An architecture that uses asmaller LV has greater total risk, even though the impact of the loss of a singlevehicleis lessened.Moreover,becausegroundinfrastructuretendstobelimitedfor

most launch vehicle systems, the management of resources such as personnel,timing,andprocessingstreamsbecomesasignificantfactorinconductingtrans-LEOmissions,dependingonhowfar themission is togoandhowdifficult itmightbe,lunarmissionsbeingeasiestandMarsmissionsbeing themostdemanding.Cost isalsoaconsideration;HLVstendtohavegreatereconomiesofscaleintermsofdollarsper kilogram delivered, but they carry higher initial development and operatingcosts.

A return to the Moon can be accomplished using smaller launch vehicles andpropellant depots. Several different architectures,with varying degrees of realism,havebeendevelopedtoaccomplishsuchamission.Inallcases,technicaldifficultiesneed to be solved before a viable transportation system is developed. The biggestunknowns are associated with the building and operation of propellant depots;delivery, storage,andtransferofpropellantare technical issues thathaveyet tobedemonstrated.Theseareparticularlyacutewithcryogenicpropellants(liquidoxygenand hydrogen) that have extremely low boiling points; some propellant willgraduallybelostthroughsublimationregardlessofhowthermallywellinsulatedthestoragetanksareatthedepot.Onewaytomitigatethislossistostorethepropellantas water and crack it into its elemental form just prior to use. Such a strategyrequires building a substantial infrastructure at the depot, including large solararraystogeneratehighlevelsofelectricalpowertocrackthewaterandprocessingfacilities to capture and freeze the dissociated gases. This approach makes depotsmuchmorecomplicatedfacilitiesthansimplestoragetanksinorbit.Itispossibletoprovision depotswith storable propellants, that is, noncryogens that aremuch lesssusceptible to boil-off loss. But storables such as hydrazine and nitrogen tetroxidehavemuchlessspecificimpulse(totalenergy)whenused,andthedepotswouldnotbe configured to accept and use lunar-produced propellant in the future. Thetechnicalcomplexitiesassociatedwithcryogenicoxygen-hydrogendepotsmaketheirdevelopmentaprotractedeffortbutaftertheirestablishment,onethatprovidesthemostextensibility,flexibility,andutilityforspacefaringinthelongrun.

Retainingcryogenicpropellantwithminimalboil-offisanimportantissue,butinaddition,transferofsupercoldliquidsinmicrogravityisaprocedurethathasyettobeattempted.Variouscomplicationsofdepotconfigurationareneededtoenablethetransfer of liquids in orbit, including the use of ullage by inert gases such aspressurizedheliumorbyspinningthedepottogeneratesmallaccelerations,causingliquids to move in a predictable direction. All of these systems need to be space-certified, meaning that moving parts must be designed for operation in extremethermal and vacuum environments, which is costly. Presumably, much of the

necessaryoperationalworkcanbeautomated,butaswehavenotyetdemonstratedthetechnologiesneededforaspace-basedcryogenicdepot,wecannotevenbegintodesigntheneededroboticsystems.Humaninterventionandadjustmentofthedepotmachinery probably will be necessary. Most likely, the earliest space-basedpropellantdepotswillbehuman-tendedbytechnicalnecessity,notbyprogrammaticrequirement.

A variety of expendable launch vehicles are now or soonwill be available thatcould implement a propellant depot-based architecture.The largestELVavailablecommerciallyistheDeltaIV-Heavy,9whichcanlift26metrictonstoLEO.UseofsuchanLVcouldconductalunarsurfacemissionwiththreelaunches.SmallerELVssuch as the Atlas 551 (21 tons) or Falcon 9 (11 tons) would require many morelaunches to stage such a mission. The proposed Falcon Heavy launch vehicle bySpaceX would consist of three strapped-together Falcon 9 vehicles with cross-fedengines.10 It remains to be seen whether this proposed rocket, with twenty-sevenenginesburningsimultaneouslyonliftoff,willworkandwhetheritwillbefiscallyviableasacommerciallaunchsystem.IftheFalconHeavydeliversasadvertised,itcouldplaceabout50metrictonsintoLEO,enoughtoconductalunarmissionwithtwolaunches.

Therearemanyways to skin the cat of trans-LEOhuman spaceflight.NASA iscurrentlybuildingaheavyliftvehiclethatwillenablehumanmissionstothelunarsurface in itsbasic, coreconfiguration (70 tons), so theestablishmentofpropellantdepotsinLEOisnotanimmediatenecessity.However,becauseoneoftheprincipalgoals of a return to the Moon is to learn how to use its resources, establishing acryogenicpropellantdepotisanessentialpieceofacompletesystemdesignedtouselunarpropellanttofuelspacetransportation.Wewillhavetoaddressandsolvethesevarioustechnicalproblemssoonerorlater,sowemightaswellbuildandlearnhowtooperatesuchasystemnow.

ALunarReturnArchitecture:LeadingwithRobotsSeveral attempts to establish human presence on theMoonwere abandoned aftertheyfounderedonfiscalandpoliticalshoals.Whiletherearemanyreasonsforthishistory,oneoftheprincipalonesisthecontinuedandrepeatedattemptoverthelastthirty years to re-create the Apollo experience. Apollo, one of NASA’s finestaccomplishments, took America from essentially zero spaceflight capability to thesurface of the Moon in eight years. Unfortunately, this success led the agency toconcludethatmakingleapsintechnologyandcapabilitythroughtheappropriation

andexpenditureofmassiveamountsof federalmoneywas theonlyviablepath tospace success. Such an eventuality is extremely unlikely to reoccur. For theforeseeable future, the civil space program will probably be restricted to fundinglevels of less than one percent of the federal budget, and perhapsmuch less thanthat.

Giventheserestraints,isatrans-LEOhumanspaceflightprogramevenpossible?Ibelieveitis,butwemustdesignanapproachthatspendsmoneycarefully,investsinlastinginfrastructure,andusestheresourcesofspacetocreatenewcapability.Overthelastdecade,newdataobtainedfortheMoonhaveshownthatthereisabundantwatericeatthelunarpoles.Moreover,thisiceisproximatetolocationsthatreceivenear-constantsolarillumination.Thesetwofactsallowustoenvisionbothalocationandanactivityincislunarspacewhereanoff-planetfootholdforhumanitycouldbeestablished.Thedevelopmentofanarchitecturethatworksundertheseconstraintsandachieves theobjectivesdescribedabovewasa joint effortbymyself andTonyLavoie,anengineerfromNASA–MarshallSpaceFlightCenterwithwhomIworkedcloselyontheLunarArchitectureTeamin2006.11Itshouldbeemphasizedthatthisplan is flexible; many aspects of it can be changed to accommodate evolvingcircumstances,resources,andprevailingsocietalandpoliticalconditions.Itisofferedas an example ofwhat is possible and not as a detailedmaster plan thatmust befollowedtotheletter.

The mission statement of lunar return is “to learn how to live and workproductively on another world.” We do this by using the material and energyresourcesof the lunar surface tocreatea sustainedpresence there.Specifically,ourgoalistoharvesttheabundantwatericepresentatthelunarpoleswiththeobjectiveofmakingconsumablesforhumanresidenceonthelunarsurfaceandpropellantforaccesstoandfromtheMoonandforeventualexporttosupportactivitiesincislunarspace.Initially,thearchitecturefocusesonwaterproductionbecausepropellant—inthiscase,hydrogenandoxygen—isbyfarthemajorfractionofvehiclemassandthemost significant factor for the cost of human missions. The availability of lunarconsumables and propellant allow us to routinely access all the levels of cislunarspace,whereoureconomic,nationalsecurity,andscientificsatelliteassetsreside.

Theobjectiveoflunarreturndefinesourarchitecture:westayinoneplacetobuildupcapabilitiesandinfrastructureinordertostaylongerandcreatemore.Thus,webuildanoutpost;wedonotconductsortiemissionstoavarietyoflandingssitesallover theMoon.Wego to thepoles for three reasons: (1)near-permanent sunlightnear the poles permits almost constant generation of electrical power fromphotovoltaics, obviating the need for a nuclear reactor to survive the fourteen-day

lunarnight; (2) thesequasi-permanent lit zonesare thermallybenigncompared toequatorialregions(Apollosites),beingilluminatedatgrazingsolarincidenceangles,andthusgreatlyreducethepassivethermalloadingfromthehotlunarsurface;(3)thepermanentlydarkareasnear thepolescontainsignificantquantitiesofvolatilesubstances,includinghundredsofmillionsoftonsofwaterice.

The return to theMoon isaccomplishedgraduallyand in stages,makinguseofexistingassetsbothonEarthandinspace.Earlymissionssendroboticmachinesthatare controlled by operators on theEarth.The short radio time-delay permits nearinstantaneousresponsetoteleoperations,avirtueprovidedbytheMoon’sproximityto Earth. An important attribute of this architecture is flexibility. We buildinfrastructure incrementally with small pieces on the Moon, operated as a singlelarge, distributed system. The individual robotic machines have high-definition,stereo real-time imaging, anthropomorphic manipulation capabilities, and possessfingerlikeend-effectors.The intent is togive the robotic teleoperators the senseofbeing physically present and working on the Moon. These surface facilities areemplacedandoperatedasopportunityandcapabilitypermit.Becausetherearemanysmallpiecesandsegmentsinvolvedinadistributedsystem,anincrementalapproachenables a broader participation in lunar return by international and commercialpartnersthanwaspossibleunderpreviousarchitectures.

The advantage of using smaller units for robotic machines is that they can beeithergroupedtogetherandlaunchedononelargeHLVorlaunchedseparatelyonmultiple,smallerELVs.SuchflexibilityallowsustocreateafootholdontheMoonirrespectiveofbudgetaryfluctuations.Commonalityoccursat thecomponent level,withcommoncryogenicengines,valves,avionicsboxes, landingsubsystems, filters,andconnectorstoallowmaximumuseandreuseoftheassetsthatarelandedonthesurface.Thegoal is to createa remotelyoperated, roboticwatermining stationontheMoon.Peoplearriveattheoutpostlateintheplantocannibalizecommonparts,fixproblems,conductperiodicmaintenance,upgradesoftgoods,seals,valvepacking,inspect equipment for wear, and perform certain logistical and developmentalfunctionsthathumansdobest.

PhaseI:ResourceProspecting.Wefirstlaunchaseriesofsmallroboticspacecraftto: (1) emplace critical communications and navigational assets; (2) prospect thepolar regions to identify suitable sites for resourcemining and processing; and (3)demonstrate the steps necessary to find, extract, process and store water and itsderivative products. The poles of the Moon have intermittent visibility with theEarth,whichcreatesproblemsforoperationsthatdependonconstant,data-intensivecommunications between Earth and the Moon. Moreover, knowledge of precise

locationsontheMoonisdifficulttodetermineandtransittoandfromspecificpointsrequireshigh-qualitymaps andnavigational aids.To resolve both theseneeds,weestablish a small constellation of satellites that serves as a communications relaysystem, providing near-constant contact between Earth and the various spacecraftaround and on theMoon, aswell as a lunarGPS systemwhich provides detailedpositionalinformation,bothonthelunarsurfaceandincislunarspace.Thissystemcanbeimplementedwithaconstellationofsmall(~250kg)satellitesinpolarorbits(apolune~2,000km)aroundtheMoon.Suchasystemmustbeabletoprovidehighbandwidth (several tens to hundreds ofMbps) for communications and positionalaccuracy (within 100 m) necessary to support transit and navigation around thelunarpoles.

Tworoverswillbesenttoeachlunarpoletoexplorethelightanddarkareasandto characterize the physical and chemical nature of the ice deposits. We mustunderstandhowpolar ice varies in concentrationhorizontally and vertically, learnabout thegeotechnicalpropertiesofpolar soils,andpinpoint locationandaccess tominingprospects.Theroverswillbeginthelong-termtaskofprospectingforlunaricedepositssothatwemayselecttheoutpostsitenearhigh-concentrationdepositsofwater.Inadditiontopolarice,wemustalsounderstandthelocationsandvariabilityof sunlit areas, as well as the dust, surface electrical-charging and plasmaenvironment.

The rovers weigh about five hundred kilograms and carry instrumentation tomeasure the physical and chemical nature of the polar ice. In addition, they willexcavate(viascoop,mole,and/ordrill)andstoresmallamountsofice/soilfeedstockfortransporttoresourcedemonstrationexperimentsmountedonthefixedlanderinthe permanent sunlight. Because the rover must journey into and out of thepermanentdarkness repeatedly, it cannot rely solelyon solararrays togenerate itselectricalpower.Powerhastobeprovidedbyacontinuouslyoperatingsystem,suchas a radioisotope thermal generator (RTG).12 Possible nonnuclear alternativesincluderechargeablebatteriesoraregenerativefuelcell(RFC).

During thisphase, apropellantdepotwillbeplaced ina400kmEarthorbit tofuel future spacecraft going to the Moon. Initially, the depot will be supplied bywaterdelivered fromEarth,but later from theMoonvia space tugs.At thedepot,waterwillbeconvertedintogaseoushydrogenandoxygenandthenwillbeliquefiedand stored.This depotwill fuel a robotic heavy landerwith roughly eightmetrictons of propellant and must be flexible enough to control its attitude in manyconfigurationsduringboth theabsenceandpresenceofdockedvehicles.Using thedepottofuelalargelanderincreasesourpotentiallandedmassontheMoonbymore

thanafactoroftwo.Thedepotwillbesuppliedinitiallywithwaterbycommerciallaunch vendors, which can begin immediately after orbit emplacement andcheckout. If no commercial providers emerge, separateNASAmissions can supplythedepotwithwater.

Phase II: Resource Mining, Processing, and Production. The next phase movesfrom resource prospecting and exploration to water production. The initialprocessing approach will be to excavate ice-laden soil, heat it to vaporize the ice,collect thevapor, and store it for lateruse. It is possible that other,more efficientminingschemes, suchassometypeof in-placeextraction,mayemergethatdonotrequiresoilexcavation.Fornow,themostconservativeapproach,onethatweknowwillwork,istouseheattodrivethewaterfromthesoil.Theprocessofsoilheatinghas the advantage of being able to use either electrical power or passive solarthermalenergytogenerateheatfortheprocessingofthefeedstock.

Figure 7.1.Artist’s rendering of robotic lander approaching surface. Previous lander has deployed solar arrays

that rotate on vertical axis, to track Sun near pole. These robotic systems can begin the work of resource

processingatthelunarpoles.(Credit7.1)

Duringthisphase,weincrementallyaddexcavators,dumphaulers,soilprocessors,andstoragetankstoobtain,haul,andstorethewater.13Landerscarryinglargesolararrays generate electricity at the permanently illuminated (> 80%) sites; roboticequipment can periodically connect to these power stations to recharge theirbatteries (figure 7.1). Our immediate goals are to learn how to remotely operatethesemachinesandbegintoproduceandstorewaterforeventualusewhenpeoplearrive.Processedwater iseasilystoredinthepermanentlyshadowedareas.Duringthisphasewealsolandelectrolysisunitstobegincrackingwaterintoitscomponentgases, making the cryogens, and storing the liquid propellant. Because we aredevelopinganoperationalcadenceaswego,itmighttakeseveralmonthstogetintoa smooth rhythm that maximizes the rates of propellant production. Largeunknowns that must be resolved include transit time between the mining andpropellant production site, thermal profiles, power profiles, and the lifetime ofmachineparts.Wemakeconstant,steadyprogress,learninghowtocrawlbeforewe

trytowalk.Equipment used in this phase includes excavation rovers, processors, and power

units, each on the order of 1,200–1,500 kilograms. Power stations are rolled solararraysthatwhendeployed,aregimbaledaboutaverticalaxistotrackthecourseoftheSunoveralunarday.Eacharraygeneratesabout25kW.Multiplepowerstationscan be arranged and operated together to provide the power needs of the roboticequipmentand,ultimately, theoutpost.During thisphase,webegin to investigatethe making of roads and cleared work areas by microwave sintering of regolith.Many areas near the outpost site, particularly around the power stations, will getheavy repeat traffic and keeping scattered dust to a minimum is necessary forthermalcontrolandtomaximizetheequipmentlifetime.

Figure 7.2.Artist’s rendering of robotic bulldozers digging ice-laden regolith as feedstock forwater extraction

processing.TheproximityofEarthallowsus to teleoperate roboticmachineson theMoonandbegin resource

processingpriortohumanarrival.(Credit7.2)

Phase III: Outpost Infrastructure Emplacement and Assembly. The next phasewillbringpiecesoftheoutpostandprepareitssite,emplacecriticalinfrastructureforpower generation and thermal control, and begin to construct the lunar surfacetransportationhub,whichwill receiveandservice the reusable roboticandhumanlandersthatmakeupourcislunartransportationsystem.Additionalroboticassetsareadded,includingupgradingthesurfaceminingandprocessingequipment,replacingdamaged items, andexpanding the capacityofprocessing (figure7.2).Ourgoal inthisphaseofdevelopmentistoincreasetheoutputofwaterinordertosupportthearrivalofhumancrewsontheMoon.

Propellantisneededonthelunarsurfacetorefueltheroboticandhumanlandersthat travel to and from theMoon.Returning cargo landers can carry theexportedproduct aswater or as propellant.Both optionsmaybenecessary, since propellantwill be needed in the vicinity of the Moon to refuel transfer stages, but waterdeliveredtolowEarthorbitcanbecrackedandfrozentherejustasefficientlyasonthelunarsurface.Includedinthepowerbudgetistheenergyrequiredforpropellantliquefaction,whichremovesalargeamountofheatfromthefluid.Minimizingthe

boil-off of the volatile cryogens is a recognized technical challenge and will beaddressedviaselectedtechnologydevelopmentearlyinthiscampaign.

Thefirstheavycargomissionwillbringthelogisticalpiecesandpowercapabilitynecessarytosupporthumanhabitationfortheinitialstayonthelunarsurface.Partof this cargo includes additional power generation capability to power the humanhabitat arriving later. The initial cargo complement would probably not includeenoughbatterypower toweather an eclipse, but it is expected that this capabilitywould arrive by the third cargo mission. Part of this complement would besupplementary equipment needed to attach to the habitat or otherwise make itusable, such as leveling equipment, high priority spares, filters, thermal shields,various pieces of support equipment, lifting equipment, mobile pallets, EVA suitcomponents, and logistics supplies, including amethod to transfer the crew to thehabitatintheformofatunnel/airlocksothatthemassofthehumanlandercanbeminimized. Included is a small, pressurized human rover (4.5 tons) to interfacebetween the lander and the habitat to allow shirtsleeve ingress, as well as localmobilitytoaccessdeployedequipment.

ThesecondheavycargomissionbringsthehumanhabitattotheMoon.Whileitisenvisionedthatthehabitableareasattheoutpostultimatelywillbesignificantlylarger than a single 12-ton module, initial needs are to have sufficient habitablevolumetosupporttwotofourcrewmembersforamonth.Includedineitherthisorthepreviousmissionpayloadareradiatorsandheatrejectionequipment,aswellasafullyoperationalenvironmentalcontrolandlifesupportsystem.

PhaseIV:HumanLunarReturn.Duringthisphase,wepreparethesite,emplacetheelements,andconnectallthepiecestocreateaready-to-useoutpost.Thosepiecesincludepowerandthermalcontrolsystems,habitats,workshops,landingpads,roads,and other facilities. Remotely operated robotic machines assemble this entirecomplexbeforepeoplearrive.Theoutpostis“human-tended”andsupportsacrewoffour for biannual visits of several weeks duration.During these periods, the crewrepairs, services and operates the previously emplaced robotic assets. In addition,someofthecrewwillconductlocalgeologicalexplorationandotherscience-relatedtasks.Bythetimethefirstcrewarrives,theoutpostwillbeproducingabout150tonsofwaterperyear,enoughtocompletelysupplythelunartransportationsystemwithpropellant.

The lander for these human missions is a smaller, LM-class vehicle (~30 ton)ratherthanalandersimilartotheConstellationAltairvehicle(~50ton).Itsprimarymission is to transport crew to and from the lunar surface and does not containsignificant life-support capability, since the crewwill live in previously emplaced

surfacehabitatswhiletheyareontheMoon.Thislunartaxibecomesapermanentpartof thecislunar transportationsystem.It is reusableandrefuelablewith lunar-producedpropellantandcanbestoredeitheronthelunarsurfaceoratthecislunartransport node. Because of its similarity in size and functionality to the roboticlanders, common components are used so that the parts count for lunar surfacemaintenance can beminimized. Specifically, both landers use a common reusablecryogenicenginedevelopedinpart(ortotally)forusebytheroboticheavylander,with both vehicles using a multiple engine complement for reliability andredundancy,aswellascost.EngineswillbedesignedtobeservicedorchangedoutontheMoon,thusmaximizingthelifetimeofthevehiclesinwhichtheyreside.

WithrefuelingattheLEOdepot,acargovariantofthehumanlanderlaunchedonaHLVcandeliver12tonsofpayloadtothelunarsurface.OnceontheMoon,itwillbecannibalizedandusedforparts.Thelanderhasadrymassof8,300kgandislaunched from the LEO station using a Cislunar Transfer Stage (CTS), whichrequires about 60,000 kg of cryogenic propellant to take the lander to the Moon.Initially,theCTSwillbeusedanddiscarded,butoncelunarpropellantproductionisupandrunning,wecanreusethiselementbyrendezvousinginlowlunarorbitwiththe cislunardepot.This architecturedoesnot presume full successwith extractinglunarresources,exceptforrefuelingforhumanEarthreturn.Astheconceptmaturesand our understanding of the logistics, cost, and sustainability of this approachsolidifies, the lunar refueling process can expand significantly, as much as thedemandwillallow,toincludetheincorporationofthecargolanders.

PhaseVandbeyond:HumanHabitationoftheMoon.Oncetheoutposthasbeenestablished, initial human occupancy will consist of periodic visits designed toexplorethelocalsiteandtomaintainandassuretheproperoperationoftheminingand production equipment. These visits will be interspersed with the landing ofadditionalroboticassetstocontinuallyincreasethelevelofproduction,withtheaimof exporting surplus water to cislunar space. Initially, the crew will validate andensure thepropellant andwater production chain, includingperiodicmaintenanceand optimization of the operations concepts and timelines.With subsequent cargodeliveries, the crew will evaluate production techniques, procedures, technologies,andtoolsthatallowexpansiontothenextstepinutilization(figure7.3).

Figure 7.3. Example of resource processing at a lunar outpost during early phases of operation. A vacuum

induction furnace takes metal obtained from the regolith, melts it and pours the liquid into molds to make

metallicmembersforconstruction.Acraneatrightisunloadingapayloadfromaroboticlander.Electricalpower

isprovidedbysolararraylandersinthedistanceattopleft.(Credit7.3)

Although the concept of lunar resource utilization has been studied for years,many unknowns need to be addressed, starting with basic technologies andtechnologyapplications in the lunarenvironment.Techniques, tools,andextensivephysicalandmetallurgicalanalysisofthepropertiesofthefinalproductsneedtobeexaminedtoobtainthebestproductsforasyetundefinedapplications.Researchinthis technology is vitally important to extending human reach in space, althoughhabitat upkeep and propellant supply chain management has higher priority. Abroad ISRU material investigation lends itself well to both internationalparticipationandcommercialdevelopment.Becausenosinglestrategyortechnologyor method works for every application, research can be divided into discreteinvestigations.Towardthatend,ononeofthecargomissions,amaterialsprocessinglaboratory is delivered. Next in priority for crew time is data on biologicalinteractionandplantgrowthinlunargravity.Theseinvestigationswillexaminethevitality,reaction,andlong-termlogisticalneedsfordevelopinglocalfoodproduction

tosustainhumanhabitationoftheMoon.At this stage, we may begin to recoup our investment in the outpost. Several

possible models for the privatization of water processing may be viable. Weanticipatethatthefederalgovernmentwillbeanearlyandrepeatcustomerforlunarwater,notonly for futureNASAmissionsbeyond theEarth-Moon systembutalsofor the cislunar missions of other agencies, such as the Department of Defense.Additionally, international customers will likely emerge. Whether the productionfacilities become commercialized before or after these markets emerge cannot beeasilyforeseenatthisstageandinfact,isunimportant.Thecriticalpointisthatwewillbe inaposition to industrialize theMoonandcislunar space,a cornerstone inmaking space part of our economic sphere. We can openly share the technologydevelopmentsaswellasanyundesirableoutcomesandpitfallsfromourexperience,sothatotherscanleveragewhatwehavelearned.Thiswillenablethecommercialsectortotakeovermanylunaractivitiesandservices.

The transition to commercial activity may occur early or late in outpostdevelopment.PartofNASA’sultimatepurposeistoexpandandenhancethenation’scommercialandindustrialbaseandthisactivityistobeencouragedwherepossible.However, in contrast toNASA’s obsessionwithdevising an“exit strategy” for theMoon,weshouldinsteadplantoparticipateinlunardevelopmentforatleastaslongas deemed necessary for fully commercial (that is, not government subsidized)providers to emerge. Because the capabilities we are developing have criticalnational strategic importance, the involvement of the federal government isimportant to ensure continuing access to lunar resources and the capabilities theyprovide.

EstablishingapermanentfootholdontheMoonopensthespacefrontiertomanydifferent uses. By creating a reusable, extensible cislunar spacefaring system, webuilda“transcontinentalrailroad”inspace,connectingtwoworlds,EarthandMoon,aswellasenablingaccess toall thepoints inbetween.WewillhaveasystemthatcanaccesstheentireMoon,butmoreimportantly,wecanalsoroutinelyaccessallofourassetswithincislunarspace:communications,GPS,weather,remotesensing,andstrategic monitoring satellites. These satellites can be serviced, maintained, andreplacedastheyage.

Ihaveconcentratedonwaterproductionatalunaroutpostbecausesuchactivityprovides the highest leverage through themaking of rocket propellant. However,there are other possibilities to explore, including a paradigm-shifting culture toeventually design all structural elements of space hardware using lunar resources.These activities will spur new commercial space interest, innovation, and

investment.This further reduces themass needed fromEarth’s logistics train andhelpsextendhumanreachdeeperintospace,alongatrajectorythatisincremental,methodical, and sustainable within projected budget expectations. Instead of thecurrent design-build-launch-discard paradigm of space operations, we can buildextensible, distributed space systemswith capabilitiesmuchgreater than currentlypossible.Both the space shuttle and the ISS experience demonstrated the value ofhuman construction and servicing of orbital systems.Whatwe have lacked is theability to access thevarious systems that orbit theEarthat altitudesmuchgreaterthanLEO—MEO,GEO,andotherlocationsincislunarspace.

A transportation system that can access cislunar space can also take us to theplanets. The assembly and fueling of interplanetarymissions is possible using theresourcesoftheMoon.WaterproducedatthelunarpolescanfuelhumanmissionsbeyondtheEarth-Moonsystem,aswellasprovideradiationshieldingforthecrew,therebygreatlyreducingtheamountofmasslaunchedfromtheEarth’ssurface.Togivesomeideaoftheleveragethisprovides,ithasbeenestimatedthatachemicallypropelledMarsmissionrequiresatleastroughlyonemillionpounds(about500tons)in Earth orbit. Of thismass,more than 80 percent is propellant. Launching suchpropellantfromEarthrequireseighttotwelveHLVlaunchesatacostofalmost$2billion each. Such an approach does not establish a true exploration capability. AMars mission staged from the facilities of a cislunar transport system can usepropellantfromtheMoontoreducethemasslaunchedfromtheEarthbyafactoroffive.

Themodular,incrementalnatureofthisarchitecturefacilitatesinternationalandcommercialparticipationbyallowingtheircontributionstobeeasilyandseamlesslyintegratedintothelunardevelopmentscenario.Becausetheoutpostisbuiltaroundtheadditionofcapabilitiesthroughtheuseofsmall,roboticallyteleoperatedassets,other parties can bring their own pieces to the table as time, availability andcapability permit. International partners will be able to contemplate their ownhumanmissions to theMoonwithout the need to develop a heavy-lift vehicle bypurchasinglunarfuelforareturntrip.Flexibilityandtheuseofincrementalpiecesmake international participation and commercialization in this architecture easierthanundertheProjectConstellationarchitecture.

These are only the initial steps of a lunar return based on resource utilization.Water is both the easiest andmost useful substance thatwe can extract from theMoonandusetoestablishacislunarspacefaringtransportationinfrastructure.Onceestablished,many different possibilities for the lunar outpostmay emerge. Itmayevolve into a commercial facility that manufactures water, propellant, and other

commodities for sale in cislunar space. It could remain a government laboratory,exploring the trade space of resource utilization by experimenting with newprocessesandproducts.Alternatively, itmightbecomea scientific research station,supporting detailed surface investigations to understand the planetary and solarhistory recorded on the Moon. We may decide to internationalize the outpost,creating a common use facility for science, exploration, research, and commercialactivity by many countries. By emphasizing resource extraction early, we createopportunities for flexible growth and for the evolution of a wide variety ofspaceflightactivities.

Schedules,Budgets,Politics,and“Sustainability”:IsAnyofThisPossible?It is anarticleof faith in the space community that theUScivil spaceprogram iswoefullyunder-fundedandshouldreceivemuchmoremoney;someadvocateforatleastdoublingthecurrentNASAbudget.Isitreallytruethatthespaceprogramdoesnotreceiveenoughmoney?Certainly, thespaceprogramisnowfundedatamuchlowerfractionofthefederalbudget(about0.3percent)thanwasappropriatedattheheightoftheApolloprogram(about4percent).14Butatthattime(1961–68),NASAhad virtually no infrastructure, including laboratories, offices, test stands, launchcomplexes, and supporting facilities, and littleoff-the-shelf technology todrawon.MuchoftheApollospendingwenttotheseendsandcreatedasupportingnetworkandorganizationalbasethattheagencyhasusedanddrawnuponforallofitsmanyprogramseversince.

As we have seen, previous efforts to return to the Moon were cut short bybudgetaryshortfalls.InWashington,theestimatesforthecostofnewprogramshavea long history of running significantly lower than what things actually andeventually cost. Nonetheless, one problem with talking about money is that thecumulativecostsforamultiyearormultidecadalprogramseemhorrendouslyhigh.15As implemented by the 90-Day Study to support President George H. W. Bush’s1989SpaceExplorationInitiative(SEI), theestimatedcostwas$600billion;at thetime, the agency’s yearly budget was a bit more than $10 billion. But that $600billionnumberwas the total cost of a thirty-year programand included all of theancillary costs of facilities and overhead.Even though few federal programs couldwithstandsuchaccountingscrutiny,criticsusedthe$600billionnumberasacudgeltobeattheSEItodeath.Onemightstopandconsiderthaninthetwenty-fiveyearssinceSEIwasunveiled, theagencyhasspentabout$498billion(FY2014)dollars,

almost the same gasp-inducing number as that of the 90-Day Study. One mightpauseandreflectonwhatthatsumhasboughtusintermsofspacefaringcapabilityoverthelasttwoandahalfdecades.

Rushinginwherebudgetaryangelsfeartotread,Inowpresent,intable7.1,ourestimateforthecostoflunarreturnviathescenariodescribedinthischapter.16TonyLavoieandIassumedfederalbudgetausterityfortheindefinitefutureandusedthebudgetguidelinesfortheagencyassumedbythe2009Augustinecommitteeasacostcap; ineffect,amaximumof$7billion(FY2011)constantdollarsperyear is tobespent on“exploration systems.”17TheAugustine committee concluded thatNASAcould not return to theMoonunder these fiscal constraints and suggested that anadditional$3billionperyearwouldbeneededtofulfill theVSEgoals.Wesimplydidnotbelievethatconclusionandthatdisagreementwasinpartthemotivationforwriting our paper.We found that by carefully defining ourmission objectives upfrontandusingremotelycontrolledroboticsystemsontheMoonintheearlystagesof theprogram,wecouldcreateapermanent resource-processingoutpostatoneofthepolesunderfairlytightfiscalrestrictions.Ourplancostsanaggregatetotalof$88billion (FY 2011) constant dollars over the course of about sixteen years. Thatamountincludesthecostofthedevelopmentoftheroboticinfrastructure,propellantdepots, reusable lunar lander, theCEV, and amediumHLV (70 ton class). It alsoincludesallofthecommercialELVlaunchcostsatthethen-quotedrates.Attheendofthisnominalprogram,wehaveanoperating,human-tendedpolaroutpostontheMoonthatproduces150tonsofwaterperyear.

Table7.1.CostDataforRoboticLunarArchitecture

AllcostsareinmillionsofUSFY2011dollars.Costforeachmissionand/ormissionelementshownin“Total”

columnatfarright;yearlycostsshownacrossbottomrow;totalprogramcostatbottomfarright.Humanmission

costsshowninbolditalic.

CostsincludetwoversionsofOrioncrewexplorationvehicle(CEV),medium-classheavyliftvehicle(HLV,70metric

ton),technologydevelopmentfunds,andoperationscostsshownatbottom.

Acritical aspect related to cost isprogramperformance.Anyhuman spaceflightprogrammustshowcontinualprogressinordertomaintainitsleveloffunding.Thebest way to accomplish this is to attain significant and recognizable intermediatemilestonesonacontinuingandregularbasis.Amanagerhasmuchmorecredibilitywhenhecanreportprogramaccomplishmentsasheasksforthenextincrementsoffunding. Part of the problemwith Project Constellationwas that its intermediatemilestoneswere too few and far between. In the five years that program ran, theonlysignificantmilestonewasalaunchtestin2009oftheAres-X,basicallyafour-segmentshuttlesolid-rocketboosterwithadummyupperstage.Whentheprogramwas cancelled in 2010, flight tests ofOrion into orbitwerenot scheduled tobeginuntil2015.Lunarreturnwasoveradecadeaway;theAugustineCommitteeclaimed

that itwouldnot occuruntil after2030, a completelyundocumentedassertionbutoneembracedbytheopponentsoftheVSE,whowereeagertoterminatethewholeeffort.TheConstellationprogram’sownlackofnear-termmilestones,accomplishedonaregularcadence,allowedthisassertiontogounchallenged.

By crafting an incremental program using smaller spacecraft, flight rates aredramatically increased and consequently, many intermediate milestones areachieved early and often. Yet, no capability is lost because the small pieces areoperatedtogetherasasingle,large“systemofsystems.”Inaddition,aprogramthatis divided into small pieces ismore robust in that it can survivebudgetary stormswithmoreresilience.Lessprogressismadeduringleantimes,butsomeprogressisstill made. It is also easier to take advantage of technical breakthroughs andincorporatethemintotheprogrambecausesystemandvehicledesignsarenotfrozenin place decades ahead of time. As mentioned, an incremental program alsofacilitatestheintegrationofcommercialandinternationalpartners,withmore“on-ramps” and a lower bar to program entry. Moreover, the possible failure or poorperformance of an individual partner has less impact on program progress andviability.

Itisdifficulttosustainlarge-scaletechnologicalprojectsoverperiodsofmorethanafewyears.InthehistoryofAmerica,onlyafewsuchprogramshavesucceededandalmostallweresomehowrelatedtonationalsecurityconcerns.Asweshallsee, theprogram to develop a permanent cislunar transportation system is no exception.Although I have described this program as a return to theMoon, it is also a steptowardthecreationofapermanentspacefaringcapability.Bybuildingthissystem,we access on a routine basis, not only the lunar surface, but also all of the otherpointswithin cislunar space, where our national scientific, economic, and securityassets reside. Other nations are well aware of the security dimensions of thiscapability, and some, such as China, are actively pursuing the means to possessfreedomofaccesstothistheaterofoperations.Aprogramtocreatetruespacefaringcapability has many critical national benefits that transcend politics. A nationalbipartisanconsensushasdefendedthisnationonland,atseaandintheairformorethantwohundredyears.Canweaffordtodolessonthenewoceanofspace?

A

8IfNotNow,When?IfNotUs,Who?

widespread misconception about the nature and meaning of the Apolloprogram has greatly contributed to our inability to establish a long-term

strategic direction for our civil spaceprogram.Essentially,Apollowas aColdWarbattlebetweentheUnitedStatesandtheSovietUnion.Oncethatpresidentialgoalhadbeenachievedandvictorydeclared,wemovedon,sinceyoudon’tkeepfightinga battle that you’ve already won. The norm for America’s relationship with theMoon has been on-again, off-again ever since. We raced to the Moon with wildabandonand then leftwithequal, ifnotgreater,haste.Afterachievingoneof thegreatestnationaltechnologicalchallengessincetheatomicbomb,AmericadepartedtheMoonwithdispatch.ThedamagecausedbymisreadingthetruesignificanceofApolloispalpable.

Apollo’s success dramatically and unquestionably demonstrated that humanspaceflight into the solar systemispossible,aknowledgepermanentlyengraved inthemindsandontheheartsofsomanyinthespacecommunity.ThosewhomadeApollopossibleview that era as a lost“goldenage”of space exploration,with theensuing years reduced to the prosaic andmundane tasks of satellite servicing andeducational, zero-gravity demonstrations. Ironically, the success of Apollo hascontributed to our multidecadal inability to move forward; it has become thecrippling, carved-in-stone standard that continues to influence current thinkingabout our civil space program. Witness the approach of our recent lunar returnefforts: Each one followed thewell-trod pathwhereinwe devised and planned anApollo-likeprogram,then,takingourcuefrompreviousefforts,promptlyretreatedwhenstacksofcashmagicallyfailedtoappearonschedule.

It ispossible thatwhat’smissing inourdebateoverareturnto theMoon is thebenefit of a clear-eyed historical perspective, one unique to America. There is noperfectanalogytothespaceprogram,butseveralpasteventsinournation’shistorysuggest that somegeneral inferencesmaybedrawn.Byexaminingsomehistoricalresonancesofspaceflightandattemptingtodrawconclusionsaboutitsproperplaceand significance, perhaps we can discern a more productive, less disruptive pathtowardspacecapability.

LunarReturninHistoricalPerspectiveThe United States has undertaken many large-scale, collective projects over thecourseofits240-yearhistory,butnonemoremythologizedthantheefforttoputamanontheMoonaheadoftheSovietUnioninthe1960s.TheApolloprogramhasall of the appeal of great drama:A charismatic,martyredpresident issues a grandand seemingly near-impossible challenge to the nation, one eagerly grasped andaccomplishedbyacan-docountry,provingonceandforallthatthegoodguyswinintheend.Itisremarkablehowthiscaricatureissowidelyaccepted.Infact,PresidentKennedywasareluctantspacefarerwhoundertooktherace to theMoononlyasawaytodistractpublicattentionfromtheless-than-stellarbeginningofhisfirstterm.Kennedyhadardentlyaskedadvisorstocomeupwithsomeothertechnicalcontest,something with a practical benefit that could win over friends and allies indevelopingnations.Thedesalinationofseawaterwashispersonalfavorite.1

Butspacewasmakingheadlinesinthelate1950sandearly1960s.AtthetimeofKennedy’sdeclarationinMay1961,itwaswidelyperceivedthatwewerebehindtheSoviets, not only in space but also in nuclear capability. This was a case whereperceptionsweremoreimportantthanreality.ItdidnotmatterthattheSovietswerewoefullybehindintheproductionofmissilesthatcouldactuallydeliverawarhead.They had already humiliated the new president twice, once by thwarting hissponsoredinvasionofCuba,attheBayofPigs,andthenagainwiththeflightofYuriGagarin,thefirstmantoorbittheEarth.AmericawasbehindintheColdWarandbehind in space. Something needed to be done. What followed held momentousconsequencesforbothColdWarrivals,andbyextension,allnations.

Apollowasaspecialproduct,oneofitsowntimeandspace;itdoesnotfitintoanycurrentrecognizablecategoryofcircumstancessurroundingthecreationofa large-scalefederalengineeringproject.ButthatdoesnotmeanthatareturntotheMoontodayisnotfeasible.Traditionally,suchprojectsareundertakenforeconomicand/orsecurity concerns. Bothmotivations are applicable to the problem of lunar return,andassuch,answerbothofthesecompellingnationalneeds.

Atthetimeofthe1849Californiagoldrush,therewereonlytwowaystogettothe goldfields.Onewas a long and tedious sea voyage from theEastCoast to SanFrancisco,withthechoiceoftakingthelongroutearoundthetipofSouthAmericaortraversingthemalarialswampsofPanamaforashiptransfermidwaythroughthevoyage.Theotherwasahazardous,months-longcrawlacrossthecontinentthroughthe wilderness of the American interior. The need for a railroad to connect thenation together was a pressing concern. Several visionaries advocated for theconstructionofatranscontinentalrailroadtoconnectCaliforniawiththerailsystems

of the east. After a long study and critical review of several routes, a path wasselectedand its constructionwasapprovedby theCongressand signed into lawbyPresident Abraham Lincoln. The Pacific Railroad Act of 1862 provided financialincentivesandlandgrantsbythefederalgovernmentforeachsegmentofrailbuiltalong the approved route. TheUnion Pacific and Central Pacific railroads startedbuilding inward from their termini (Omaha and Sacramento, respectively) andconverged atPromontoryPoint,Utah, in 1869.The teams symbolized the linkingtogether of the nation by the transcontinental railroad with the hammering of afinalgoldenspike.Nowbothcoastswereaccessible,andthecontinentalinteriorwasopentomigration,development,andsettlement.

Somebelieve that such an approach is a possiblemodel for thedevelopment ofspace.Inplaceofagovernment-runspaceprogram,governmentprovidesaseriesofincentivesandgrantswherebyprivatecompaniesareinducedtocreatethenecessaryspacefaring infrastructure that will see an economic expansion similar to thatbroughtabout150yearsearlierbythebuildingofthetranscontinentalrailroad.Thisanalogy isnotperfectlyalignedwithhistorical realities; in the1860s, anextensiverail transportation infrastructure already existed, largely capitalized by the privatesector.Comparableassetsforspaceflightconsistofcommerciallaunchsuppliers,buttheyarebothlessextensiveandhavenarrowerandsmallermarkets inthefieldofspacethandidtherailroadsofthenineteenthcenturyinthefieldofpassengerandcargotransport.Becausespaceflight ismoredifficultandmoredangerous thanrailtravel, the overall volume of traffic—and thus revenue—is much lower, whichdepresses capital investment. New Space advocates sometimes cite the US PostOffice’s airmail service of the 1920s as a good businessmodel. Although the PostOfficecontractedwithprivateaircompanies tocarrythemail, in thiscase,a largemarket (the US Mail) already existed—what was being purchased was fasterdelivery.Thatcommodityisnotnearlyasdesirableinthefieldofspaceflight,wheretimelinessislesscriticalthanassureddeliveryandreliability.

Onehistoricalparalleldoescomparecloselytoanambitiousspacegoalintermsofresourcesneeded:thedevelopmentoftheatomicbomb.2Thelargesttechnological-scientificefforteverundertaken,theManhattanProjectengagedsomeofthefinestscientific and engineering minds in the country. Billions of dollars were spentdevelopingadeliverablebomb,whose feasibilitywasuncertainwhenworkbegan.The driving imperative was national survival, always a guarantee for continuedfunding.TheconcernwasthatGermanywasactivelyworkingonatomicweapons,asuppositionlaterfoundtobeincorrect.Inanyevent,theManhattanProjectwasthelargest,mostdifficulttechnicalprojecteverattempted.Itssuccessledtotheideathat

government-fundedresearchinscienceandtechnologycouldservenationalaims,alessonsubsequentlyappliedtothewagingoftheColdWar,ofwhichApollowasonepart.The50-yearstruggleagainsttheSovietUnionledtothecreationofascience-technology industrial sector upon which we drew heavily during the Apolloprogram.Thesystematicdismantlingofthatsectorinthe1990safterthefalloftheSovietUnionmeans that techno-industrial base is gone,making progress in spacemoredifficulttoachievetoday.

Various large-scale construction projects, completed over the years, offer usefullessons inundertaking futurenational engineering efforts.TheUnited States tookoverFrencheffortstobuildthePanamaCanalin1904,completingitadecadelaterin1914.Bothengineeringexpertiseandcapitalinvestmentwerejudiciouslyappliedtotheproblemsposedbythecanal,whichrevolutionizedseafaringandworldtrade.Notedatthetimewasthesignificantnationalsecurityaspectofcanalbuilding;thePanama Canal enabled the United States Navy to easilymove ships between theAtlanticandPacificoceans,creatingaresponsiveforcemultiplierthatturnedouttobe critical during two world wars. The Interstate Highway System, proposed byPresidentDwightD.EisenhowerandinspiredbytheGermanAutobahn,createdanewautomobile-basednational transportation infrastructure. Its ostensiblepurposewas to provide a network of roads to serve the needs of national defense, but inaddition,itscreationhasbeenresponsibleforexpandingnationaleconomicactivityby trillions of dollars.Thus, large-scale government programs enabled us tomovefartherafield,togeneratewealthandprosperity,andtosecureournationaldefense.

Inpastefforts,thefederalgovernmenthasledwheretheprivatesectorhasbeenunable or unwilling. Because spaceflight is inherently a difficult undertaking, onerequiring billions of dollars in capital investment, private spaceflight, to date, hasfocusedprimarilyontheexistingsatellitelaunchmarket.Butunlikeearlyaviation,thereisnopreexisting“airpost”servicemarketdrivingthedevelopmentofanewprivatetransportationsector.Muchhopeiscurrentlyinvestedintheenvisionedbutunfulfilledpotential of space tourismasanemergingmarket.Despite cashawardsand other incentives, substantial private human spaceflight remains, for themostpart, cost-and market-prohibitive. Potential possibilities for space commerce havebeen identified in the communications, energy and construction sectors. What ismissingistheabilitytomovecargoandpeopleroutinelythroughoutcislunarspace.

The rationale for space development articulated in 2006 by formerPresidentialScience Advisor John Marburger calls for space to become part of our economicsphere.3Inpart,wehavealreadystartedtoreachthatgoal,asevidencedbyexistingcommercialmarkets for satellite communications and remote sensingdata.Due to

degradation,spaceassetsthatresideinorbitsaboveLEOneedperiodicreplacement,along with an occasional upgrade in technical capability. If we could reach thesehigh geosynchronous orbits, satellites could be serviced and maintained.Additionally,wecouldassemblelargedistributedsystemsinGEOusingpeopleandrobotsworkingtogether.Thisapproachwasdocumentedtobeofgreatvalueduringthe 30-year history of the space shuttle program, when astronauts serviced andmaintained satellites like theHubble Space Telescope and built the InternationalSpaceStationfromsmallmodulesfabricatedandlaunchedseparately.

Apermanentpresenceincislunarspaceservesmanynationaleconomicgoals.Buthowisthisbestachieved?Whataretherolesofgovernmentandtheprivatesectorinthedevelopmentofspace?Mostimportant,howcanwedeviseacivilspaceprogramthatservesthemostneeds,inthemostefficientmanner?

TheGeopoliticalValueoftheMoonandCislunarSpaceModernpowerprojectionispossibleonlythroughthedeploymentanduseofspace-based assets. Air, land, and sea forces all depend on satellites for communications,navigation,andintelligence.Withoutthem,ourabilitytomakeourwayaboutintheworldwouldbeseverelycompromised.Satellitesarephysicallyveryvulnerable.Oneneednotcollidewithonetodisableit—snappinganantennaorcuttingacabletoitssolararraycanturnabillion-dollarsatelliteintoaworthlesspieceoforbitingspacedebris. It is essential to protect our national satellite assets, both to safeguard ourinvestmentand,more importantly, toassure that theywill functionatamoment’snotice.

SomeintheNewSpacecommunitytakealibertarianviewofspacedevelopment.They suppose that government—in the form of NASA, the agency givenresponsibility for civil spaceflight—is an impediment that creates more problemsthan solutions. However, a clearly defined constitutional role of the federalgovernment is to provide for the common defense; this includes maintaining theterritorial integrity of theUnited States and the protection of legal and economicinterestsofAmericancitizensabroad.AsmoreAmericancommercialentitiesventureinto thezonesbeyond lowEarthorbit, theiractivitiesand interestsbecomepartofthedefenseobligationsoftheUSgovernment.Thus,itisnotmerelyappropriatebutessentialthatthefederalgovernmentmaintainsavisibleprofileandroleincislunarspace.

GovernmentactivitiesinspaceshouldconsistofthoseactionsdesignedtoprotectAmerican interests. This protection requires the projection of national power as

neededandappropriate,aswellastheestablishmentofalegalenvironmentwherebyindividual and corporate rights andobligations are observed anddefended. Suchaportfolio of activities requires the physical presence of government. If thegovernment isnotpresent in sucha theater,howcan it enforce its regulatoryandlegal decisions? One possibility is through asset seizure on Earth, but such atechniquewill only stifle, not encourage, space development. Just as theUSNavydefendsfreedomoftheseasandthecommerceofallnations,anAmericanpresencein cislunar spacewill likewise defend and assure freedomof access and commercethere.

TheAmericancivilspaceprogramwasoriginallyestablishedtoconductresearchinto the techniques and possible beneficial uses of spaceflight. That mandate isdeclared in the Space Act of 1958, subsequently amended many times.4 The actoutlines the role of the federal government in space and consists of nine basicobjectives, including the attainment of scientific knowledge, the development ofspace technology and flight systems, and international leadership and cooperation.The Space Act effectively authorizes NASA to conduct virtually all imaginableactivitiesinspace,includingthecreationofnewspaceflightcapabilities.

Toachieveaparadigmshiftinspaceflight,wemustunderstandhowwecanuselunarandspaceresources tocreatenewcapabilitiesandhowdifficult suchactivitymight be. Despite decades of academic study, no one has demonstrated resourceextraction on the Moon. There is nothing in the physics and chemistry of thematerialsoftheMoonthatsuggestsitisnotpossible;wesimplydonotknowwhatpracticalproblemsmightarise.Thisiswhyresourceutilizationisanappropriategoalforthefederalspaceprogram.Asahigh-riskengineeringresearchanddevelopmentproject,itisdifficultfortheprivatesectortoraisethenecessarycapitaltounderstandthemagnitude of the problem from the perspective of an end-to-end system.Theoriginal VSEwas conceived to letNASA answer these questions and to begin theprocess of creating a permanent cislunar transportation infrastructure. As anengineeringresearchanddevelopmentprojectwithuncertainprospects for success,suchaneffortisentirelyappropriateforthefederalgovernmenttoundertake.Theresultsof thisprojectcould lead to thecreationofnewmarketsandwealth,as theprivatesectorwillthenpossessthestrategicknowledgenecessarytotakeadvantageoftheeconomicopportunitiesprovidedbycislunarspacedevelopment.

ChinaandAmerica:ANewSpaceRace?Just as America is standing down from space leadership, China is stepping up its

program to send people to the Moon. This circumstance has reawakened a long-standing debate about the geopolitical aspects of space travel and with it, somequestions.AreweinaracebacktotheMoon?Shouldwebe?Andifthereisa“spacerace”today,whatdowemeanbytheterm?Isitaraceofmilitarydimensions,orissuchthinkinganartifactoftheColdWar?Whataretheimplicationsofanewspacerace?

ManywhoworkinthespacebusinesspurporttobeunimpressedbytheideathatChinaisgoingtotheMoon,evenpubliclyinvitingthemtowastemoneyonsuchastunt.“Nobigdeal”seemstobetheattitude—afterall,Americadidthatmorethan40yearsago.NASAAdministratorCharlesBoldenprofesses tobeunmovedby thepossiblefuturepresenceofaChineseflagontheMoon,havingnotedthattherearealreadysixAmericanflagsthere.Itshouldbefurthernotedthat40yearsofexposureto solar ultraviolet radiation has probably bleached and faded the red,white, andblueintoadullwhite.5

Although it is not currently fashionable in this country to think about nationalinterests and the competition of nations in space, others do not labor under theserestrictions. Our current human spaceflight effort, the International Space Station(ISS), has shown us both the benefits and drawbacks of cooperative projects.Currently,wedonothavetheabilitytosendcrewstoandfromtheISS.Butthat’snotaproblem;theRussianshavegraciouslyagreedtotransportus,at$60millionapop.

Whywouldnations compete in space, anyway? If such competition occurs, howmightitaffectus?Whatshouldwehaveinspace:KumbayaorStarshipTroopers?Oristheanswersomewhereinbetween?

The“Moonrace”ofthe1960swasaColdWarexerciseofsoftpowerprojection,meaning that it involved no real military confrontation, but rather was acompetition by nonlethal means to determine which country had superiortechnology,andbyextension,thesuperiorpoliticalandeconomicsystem.Inshort,itwaslargelyaninternationalpropagandastruggle.Simultaneously,thetwocountriesalso engaged in a hard power struggle in space to develop ever-better systems toobserveandmonitorthemilitaryassetsoftheother.Therewaslittlepublicdebateassociated with this struggle, indeed, much of it was kept secret. As the decadepassed,militaryspacesystemsbecameincreasinglymorecapableandextensive.Overtime, they largely replaced human intelligence assets monitoring our adversaries’strategiccapabilitiesandintentions.

TheUnitedStatesverypubliclywontheracetotheMoon,givingrisetoaflurryof pronouncements about everyone’s peaceful intentions for outer space,while the

largerstrugglecontinuedtoplayoutbehindthescenes.NASA’sreplacementeffortfor theconcludedApolloprogram, the space shuttleproject,promised to lower thecostsofspacetravelbyprovidingareusablevehiclethatwouldlaunchlikearocketand land like an airplane. Because of the need to fit under a tightly constrainedbudgetaryenvelope,andforavarietyofothertechnicalreasons,theshuttledidnotliveupto itspromiseasa low-cost“truck”forspaceflight.However, theprogramresulted ina fleetof fiveoperational spacecraft that successfully flew133missionsoverthecourseofits30-yearhistory.

AlthoughsomeinAmericanspacecircleshavecalleditapolicyfailure,theshuttlehadsomeinterestingcharacteristicsthatcausedittobeconsideredamilitarythreatby theUSSR. An early shuttlemission had its crew retrieve an orbiting satellite,SolarMax,forrepair.LatermissionsgrappledbalkysatellitesandreturnedthemtoEarth for refurbishment, repair, and re-launch. This capability culminatedwith aseriesofshuttlemissionstotheHubbleSpaceTelescope(HST)thatconductedon-orbit servicing tasks, ranging from correcting the flawed optics of the originaltelescope (the first service mission) to the routine upgrading of sensors, thereplacementofsolararraysandmaincomputers,andthereboostingofthetelescopetoahigherorbit.ThesignificanceofthesemissionswasthattheHSTisbasicallyastrategic reconnaissance satellite: It looks up at the heavens rather than down atnuclearmissilesitesfromorbit.TheHubblerepairmissionsdocumentedthevalueofaccessingorbitalassetswithpeopleandservicingequipment.

Anotherrelativelyunnoticedseriesofshuttlemissionsdemonstratedthevalueofadvancedsensors.Asa large, stableplatforminorbit (itsorbitingmasswasalmost100metric tons), the shuttlewasable to flyveryheavy,high-powerpayloads thatsmaller robotic satellites could not. The Shuttle Imaging Radar (SIR) was asynthetic-aperture instrument that could obtain images of Earth from space bysending out radar pulses as an illuminating beam. It was able to image throughcloudcover,dayornight,allovertheEarth.Inastunningrealization,wefoundthatitcouldalsoimagesubsurfacefeaturesfromspace—inparticular,theSIR-Amissionmapped ancient riverbeds buried beneath the sands of the eastern Sahara.6 Thestrategic implications of this discoverywere immense; asmost land-based nuclearmissiles are buried in silos, the use of sensors like imaging radarmeans that theycannotremainhidden.

These new capabilities, provided by the space shuttle, had significant policyimplications for the Soviets. To them, it seemed that the shuttlewas a great leapforward in military space technology, not the “policy failure” bemoaned byAmerican analysts. With its capabilities for on-orbit satellite servicing and as a

platformforadvancedsensors,theshuttlebecameathreatthathadtobecountered.The USSR responded with Buran, its version of a space shuttle, which lookedsuperficiallysimilartotheAmericanversion.TheChallengeraccidentshowedthatthe shuttle was a highly vulnerable system inmany respects; even as the SovietsdevelopedBuran,theAmericanmilitaryhadalreadydecidedtowithdrawfromtheshuttleprogram.

Duringthe1990s,wesawarevolutionintacticalspace—theuseof,andrelianceon,spaceassetsonthemodernbattlefield.Theglobalpositioningsystem(GPS)hasmadethetransitiontotheconsumermarket,but itwasoriginallydesignedforourtroopstoinstantlyknowtheirexactlocations.Aglobalnetworkofcommunicationssatellites carries both voice and data, and interfaces to the partly space-basedInternet, another innovation originally built formilitary technical research. Now,the entire world is connected and plugged in, and spacebridges are importantcomponents of that connection. Fifty years into the Space Age, we are all vitallydependent, both economically andmilitarily, onour satellite-based assets; space is,by default, in control ofEarth’s economic sphere.Whoever controls cislunar spacecontrolswhathappensonEarth.

Mostpeopledonotknowaboutthemultitudeofsatellitesinvariousorbitsaroundthe Earth that affect their daily lives. We rely on satellites to provide us withinstantaneousglobal communications that affect almost everythingwedo.WeuseGPS to find out bothwherewe are andwherewe are going.Weather stations inorbitmonitortheglobe,alertingustocomingstormssothattheirdestructiveeffectscan be minimized. Remote space sensors map the land and sea, permitting us tounderstand the distribution of various properties and how they changewith time.Other satellites look outward to the Sun, which controls the Earth’s climate, and“space weather,” which influences radio propagation. The satellites orbiting theEarth provide uswith phenomenal amounts of information. Fortunately, they arenotyetself-aware—butthepeoplewhooperatethemare.

All satellites are vulnerable. Components constantly break down and must bereplaced. New technology makes existing facilities obsolete, requiring high-costreplacements.Asatellitemustfitwithinandontopofthelargestlaunchvehiclewehave.Spacecraftthushavepracticalsizelimits,whichinturnlimitstheircapabilitiesandlifetimes.Onceasatellitestopsworking,itisabandonedandareplacementmustbedesigned,launched,andputintoitsproperorbit,allatgreatcost.

Although satellite aging is normal and expected, catastrophic loss, eitheraccidental or deliberate, is always a concern. Encounters between objects in spacetendtobeatveryhighvelocities.Theever-increasingamountsofdebrisandjunkin

orbit, such as pieces of old rockets and satellites, canhit functioning satellites anddestroy them.7NorthAmericanAerospaceDefense Command (NORAD) carefullytracks the bigger pieces of space junk. Some spacecraft, such as the InternationalSpaceStation,canbemaneuveredoutofthepathofbigchunksofoncomingdebris,but smaller pieces, say, the size of a bolt or screw, cannot be tracked and avoided.Such debris could cripple a satellite if it collides with some critical part of thevehicle.

Antisatellitewarfare(ASAT)isanotherpossiblecauseoffailure.Ithaslongbeenrecognized that satellites are extremely vulnerable to attack, andboth theUS andthe USSR experimented with ASAT warfare during the Cold War. ASAT takesadvantageofthefragilityofthesespacecrafttorendertheminoperative.Thiscanbedonewith remote effectors, such as lasers to “blind” optical sensors.The simplestASATweaponisakineticimpactor.Byinterceptingasatellitewithaprojectileatahigh relativevelocity, the satellite is rapidlyandeasilydisintegratedand renderedworthless.

Despitetheirvulnerability,thedestructionofspaceassetshasseldomhappenedbyaccidentandneverasanovertactofwar.Theyareleftalonebecausetheyarenoteasy to get to. Some orbiting spacecraft occupy low Earth orbit (LEO) and areaccessible to interceptors, but many valuable strategic assets reside in the muchhigherorbitsofmiddleEarthorbit(MEO)between3,000and35,000kilometers,andingeosynchronousEarthorbit(GEO)at35,786kilometers.Suchorbitsaredifficulttoreach,requiringlongtransittimesandcomplexorbitalmaneuvers,whichquicklyrevealthemselvesandtheirpurposetoground-basedtracking.

After a booster failure in 1998, a communications satellitewas left in a uselesstransfer orbit. Engineers at Hughes, the makers of the satellite, devised a cleverschemetosendthesatellitetoGEOusingagravityassistfromtheMoon.Thisfirst“commercial” use of a flight to the Moon saved the expensive satellite for itsplanned use.8 One aspect of this rescue is seldom mentioned but it attracted theattention of military space watchers everywhere. This mission dramaticallyillustrated the importanceofwhat is called“situational awareness” in space.Mosttrips to GEO travel from LEO upward; this satellite came down from the Moon,approachingGEOfromanunobserved(andat leastpartlyunobservable)direction,onenotordinarilymonitoredbyground-basedtrackingsystems.

Withfewexceptions,wearenotabletoaccesssatellitestorepairorupgradethem.Satellites must be self-contained. Once they stop working, they are replaced.Sometimes favorable conditions allowus to be clever and rescue an asset thathadbeen written off, but the system is not designed for such operation. The current

spaceflight paradigm is a use and throwaway culture. Our history with the spaceshuttleprogramdemonstratesthatthistemplateneednotbethewayofconductingbusiness in the future. What is missing is the ability to get people and servicingmachinesouttothevarioussatellitesinalltheirmyriadlocations.ReachingLEOiseasy,butMEOandGEOcannotbeaccessedwithexistingspacesystems.Yet fromtheexperienceof theshuttleandtheISS,weknowthat if thesesatellitescouldbevisited,arevolutioninthewayspaceflightisapproachedmightbepossible.

Asystemwiththeabilitytoroutinelygotoandfromthelunarsurfaceisalsoableto access any other point in cislunar space (see figure 6.1).Ournext goal in spaceshouldbetocreatethecapabilitytoinhabittheMoonandliveoffitslocalresourceswiththegoalsofself-sufficiencyandsustainability, includinglearningtheskillsofpropellantproductionandtherefuelingofcislunartransportvehicles.Eventually,wecanexportlunarpropellanttofuelingdepotsthroughoutcislunarspace.Inshort,bygoingtotheMoon,wecreateanewandqualitativelydifferentcapabilityforspaceaccess, a “transcontinental railroad” in space. Such a system would completelytransformtheparadigmofspaceflight.Wecandevelopserviceablesatellites,unlikecurrentonesdesignedtobeabandonedoncetheyfail.Thisnewcapabilitywillallowus to create extensible, upgradeable systems. The ability to transport people andmachinesthroughoutcislunarspacepermitstheconstructionofdistributedinsteadofself-containedsystems.Suchspaceassetsaremoreflexible,morecapable,andmorereadilydefendedthanconventionalones.

With knowledge of these possibilities, questions arise as to how closewe are todeveloping such a systemand if such a paradigm shift for spaceflight is desirable.Arewestillinaspacerace,oristhatanobsoleteconcept?Answerstothesequestionsare not at all obvious. We must understand and consider them fully, as thisinformationisknownoravailabletoall spacefaringnationstoadoptandadaptfortheirownuse.

Thepreviousspaceraceto landamanontheMoonwasademonstrationtotheUSSRand to theworld of our technological superiority.The July1969 landingofApollo11,byanyreckoning,gaveustechnicalcredibilityfortheColdWarendgame.ItwasahugewinforUnitedStatesandaseriousblowtocommunism.Fifteenyearsafter themoon landing,PresidentReagan advocated thedevelopment of amissiledefense shield, the so-called StrategicDefense Initiative (SDI).Althoughmany intheWestdisparaged thisas technicallyunattainable, theSoviets took theprogramveryseriously.BecausetheUnitedStateshadalreadysucceededincompletingaverydifficulttechnicaltask,themannedlunarlanding,somethingthattheSovietUnioncouldnot accomplish, theydidnot questionour technical skill or our resolve.The

SovietsknewthatadeploymentofaUSmissileshieldwouldinstantlyrendertheirentirenuclearstrategiccapabilityuseless.

NotonlydidtheApolloprogramachieveitsliteralobjectiveoflandingamanontheMoon(propaganda,softpower),butitalsoachieveditsmoreabstractobjectiveofintimidating our Soviet adversary (technical surprise, hard power).9 Apollo thusplayed a significant role in ending theColdWar, one far in excess ofwhatmanyscholarsbelieve.Similarly,ourtwofollow-onprogramsofshuttle/station,althoughfraughtwithtechnicalissuesanddeficienciesastoolsofexploration,weresignificantinourunderstandingandpursuitofhumanspaceflight,providinguswithawaytogetpeopleandmachinestosatelliteassetsforconstruction,servicing,extension,andrepair.Welearnedhowtoassembleverylargesystemsinspacefromsmallerpieces.Fromourexperienceconstructing theISS,masteryof these skills suggests that theconstructionofnew,largedistributedsystemsforcommunications,surveillance,andother tasks ispossible.Thesenewspace systemswouldbemuchmorecapableandenablingthanexistingones.

Warfare in space is not as it is depicted in science-fiction movies, with flyingsaucersblastinglasersatspeedingspaceships.Therealthreatfromspacewarfareisthedenialofassets:Communicationssatellitesaresilenced,reconnaissancesatellitesare blinded, and GPS constellations are made inoperative.10 Possessing thiscapability completely disrupts command and control and compels reliance onterrestriallybasedsystems,makingforceprojectionandcoordinationmoredifficult,cumbersome,andslower.

BytestingASATweaponsinspace,Chinahasindicatedthatitfullyunderstandsthe military benefits of hard space power.11 It also has a well-developed lunarprogram.Currently,China’sambitionofflagsandfootprintsontheMoonrepresentssoftpowerprojection.SinceonlytheUnitedStateshasdonethisinthepast,Chinawould celebrate a successful manned lunar mission as a great propaganda coup.Sendingtaikonauts,astheChinesecalltheirastronauts,beyondlowEarthorbitisastatementoftechnicalparitywiththeUnitedStates.Historicallyknownfortakingthe long view, often spanning decades, unlike the short-term view that Americafavors, China understands and appreciates the strategic importance and value ofcislunarspace.12Thus,althoughinitialChineseplans forhumanlunarmissionsdonotfeatureresourceutilization(ISRU),theyknowfromthetechnicalliteraturethatthisactivityisbothpossibleandenabling.

TheChinesearealsoawareofthevalueoftheMoonasa“backdoor”toapproachother levels of cislunar space, as demonstrated by the rescue of the Hughescommunications satellite. The lunar mission Chang’E 2 is an instructive case in

point. Ostensibly a global mapper, the Chang’E 2 spacecraft was launched to theMoon inOctober 2010. It successfully inserted into lunar orbit and spent thenexteightmonthsmappingthesurfaceindetail.Then,themissiontookastrangeturn;after leaving lunarorbit in June2011, theChang’E2 spacecraft slowly traveled totheSun-EarthL-2point(fixedinspacerelativetotheEarth)whereitproceededtoloiterforthenexteightmonths.DepartingtheL-2pointinApril2012,theChang’E2 spacecraft then intercepted and flew past and within about three kilometers ofToutatis, a near-Earth asteroid orbiting the Sun. The spacecraft successfully sentimagesandotherdataofitsencounterbacktoEarth.

This mission profile is significant in terms of space defense. The Chinesedemonstrated their ability to dispatch and maneuver a craft throughout cislunarspace, including the tasks of rendezvous and interception, and to command andoperate this vehicle throughout the multiyear duration of the mission. Loiter,interception, and action on command are three pillars of antisatellite warfare.Moreover, a spacecraft onan interceptionpath fromabove—rather thanbelow,aswould be the case for antisatellite missions launched from Earth—is much moredifficult to detect and track. In short, with the Chang’E 2 mission, Chinademonstrated that it possesses the ability to base ASATweapons in deep cislunarspaceandintercepttrans-LEOspaceassetsatwill,assetsthathaveverylittleinthewayofdefensivecapabilities.

If space resource extraction and commerce is possible, a significant questionemerges: What societal paradigm shall prevail in this new economy? Many NewSpaceadvocatesassumethatfreemarketsandcapitalismaretheobviousorganizingprinciples of space commerce, but othersmaynot agree. For example, toChina, agovernment-corporatistoligarchy,thebenefitsofapluralisticfree-marketsystemarenot obvious. Western capitalism is successful because of the enforcement of andrespectforcontract law.Implementationofcapitalisminthedevelopingworldhasmetwithmixedresults,andtrulyfreemarketsdonotexistinChina.Whatwilltheorganizingprincipleofsocietyinthenewcommerceofspaceresourcesbe:theruleoflaworauthoritarianoligarchy?AnAmericanwininthisnewraceforspacedoesnotguaranteethatfreemarketswillprevail,butanAmericanlosscouldensurethatfreemarketswouldnotemergeanddriveexpansionon thisnewfrontier.The struggleforsoftpowerprojectioninspaceisongoing.

Onceitwasdecideduponin1961,PresidentJohnF.Kennedylaidoutthereasonswhy America had to go the Moon.13 Among the many ideas he articulated, onestands out: “Whatevermen shallundertake, freemenmust fully share.”This is aclassicexpressionofAmericanexceptionalism,theideathatweexplorenewfrontiers

not to establish an empire, but to ensure that our political and economic systemprevails,asystemthathascreatedthemostfreedomandplacedthemostnewwealthinthehandsofthegreatestnumberofpeopleinthehistoryoftheworld.Thisisastatementofbothsoftandhardpowerprojection;byleadingtheworldintospace,weguarantee that space does not become the private domain of powers who viewhumanityascogsintheirideologicalmachine,butratherasindividualstobevaluedandprotected,andgiventheopportunityandlatitudetoinnovateandprosper.

TheMoon is the first destination beyondLEO because it has thematerial andenergy resourcesneeded to create a true spacefaring system.Recentdata from theMoon show that it is even richer in resource potential than we had previouslythought;bothabundantwaterandnear-permanentsunlightareavailableatselectedareas near the poles. We go to the Moon to learn how to extract and use thoseresources to create a space transportation system that can routinely access all ofcislunarspace,withbothmachinesandpeople.Suchasystemisthelogicalnextstepinboth space securityandspacecommerce.Thisgoal forNASAmakes theagencyrelevanttoimportantnationalinterests.AreturntotheMoonforresourceutilizationcontributestonationalsecurityandeconomicinterests,aswellasscientificones.

Weareinanewspacerace,anditisastrugglethathasbothhardandsoftpowerdimensions.Thisraceisrealandmorevitaltoourcountry’sfuturethantheoriginalone, if not as widely recognized and appreciated. The hard power aspect is toconfronttheabilityofothernationstodenyusaccesstoourvitalsatelliteassets incislunarspace.Thesoftpoweraspectisaquestion:Howshallsocietybeorganizedinspace? Both concerns are equally important and both can be addressed by lunarreturn. Will space remain an ever-shrinking sanctuary for science and publicrelationsstunts,orwill itbeatruefrontier,openedwidetoscientistsandpilots,aswell as miners, technicians, entrepreneurs, and settlers? Decisions made now willdecidethefateofspacefaringandaffectournationaleconomicandsecuritystatusforgenerations.

TheRoleofPublicOpinioninSpaceflightAfamiliarrefrainabout thecivil spaceprogramis thatwemustsomehowgetandkeep theAmerican people “excited” about space.NASA has spent a great deal ofenergypursuing thiselusivegoal. Itsoutreacheffortsaredesigned to convince thetaxpayers that spendingmoney on space is a good investment.Themost commonapproach is an appealmade to impress upon theAmerican people how themanybenefits from spin-off technologies, goods, and capabilities inspired or created by

spaceresearchanddevelopmenthaveaffectedtheirlivesinpositiveways.TheAldridgeCommissionreceivedapresentationfromNASAPublicAffairsthat

contained50yearsofpollingdataon thequestion,“Doyou support theAmericanspaceprogram?”Thepollnumberson thisquestionhavebouncedaround throughthe years, ranging from close to 60 percent to as low as around 40 percent.Surprisingly,nomatterwhattheagencywasdoing,howitwasfaring,whatdisastersitenduredorthetriumphsithadachieved,thetypicalbreakdownwasroughly50–50,plusorminus10percentagepoints.Thisresult,nearlyconstantoverthecourseofthe 50-year history of the space program, is as rock-solid as almost any pollingnumberinexistenceoverasimilartimespan.14

Yet,NASAwringsitshandsoverthisresult:“Howcanweexcitethepeople?Ifwecould just comeupwith the correct public relationsplan, thepublic andCongresswill shower us with money and support!” I believe that these numbers have adifferent significance. If your poll results are always around 50–50, then, in afundamentalsense,peopleareindifferentaboutwhatyouaredoing.Apparently,thepublic really doesn’t fixate on what NASA does. True enough, many do have afascinationwith spaceflight; attendance at theNationalAir and SpaceMuseum isconsistentlythehighestofallthemuseumsontheNationalMallinWashington.Butaswithanymuseumvisit,theircuriosityiseasilysatiated,andfewdwellonnationalstrategicandeconomicgoalsandobjectivesinspaceonadailybasis.

While NASA sees its 50–50 polling approval as a problem, I see it as anopportunity. In broad and vague terms, people support our space program. It is asource of national pride, andAmericans don’twant to seeNASA on the choppingblock.Theylikethe ideaofgoingtonewplacesandmakingnewdiscoveries; theyjust don’t center their thinking on the sausagemakingof spacepolicy.What theywantfromtheirgovernmentisaspaceprogramthatdoesinterestingthingsandnottoomanydumbones,withprogramsthatinspirethecountryandmakeussmarter,hopeful,andproud.

Giventhisrelativelybenignpublicmoodandafundinglevelalmostliterally“inthe noise” comparedwith other federal programs—at less than 0.3 percent of thefederalbudget,muchsmallerthanmostbelieveittobe—NASA’sstrategicdirectionshouldfocusontheincrementalbuildupofourcapabilitytogofarther,staylonger,anddevelopandincreasehuman“reach”beyondlowEarthorbit,first,intocislunarand then into interplanetary space. Our Moon is situated where it can play animportantroleinthisbuildup,sinceitisthefirstplacebeyondlowEarthorbitwiththeresourcesneededtodevelopandexpandourspacefaringcapability.Initially,thismeans oxygen and hydrogen—vital, consumable resources necessary to support a

human presence, and as rocket propellant for refueling spacecraft. Provisioning inspacebeginshere.

Perhaps the public doesn’t care about the Moon or even the space program ingeneral. But even if this is true, it is irrelevant. Few concern themselveswith therequirements and properties of infrastructure development such as railroads orhighways, yet no one denies their value, nor does it stop their productive use ofthem. As a modern, technical society, we depend upon space and the assets andresourcesfoundthere,forawidevarietyofpurposes.Inordertotakeadvantageofthese opportunities, we need freedom of movement on the ocean of space—theability to go where we need, whenever we want to. The development of lunarresourcesholdsgreatpromisebygivingustheflexibilitytopursueasetoflong-termgoalsinspace—goalsthatwillultimatelyallowustogoanywhere,foranyamountoftime,todoalmostanyjobwecanimagine,aswellasdoingthosethingsthatwecannotyetimagine.

Moonrush:IssuesinPrivateSectorLunarActivitiesA number of American companies, at differing levels of involvement and withgreatly differing degrees of technical credibility, claim to be attempting lunarspaceflight.Astimulus to thisactivity is theGoogleLunarX-Prize (GLEX),a$20million contest to safely land a payload on the Moon and conduct a number ofspecified milestone activities.15 Although this seems like a stunt, the rationalebehindGLEXisserious.Prizesareemployedbyothertechnicalfieldsofendeavortostimulate development and innovation. Winning a prize has multiple benefits: Itawardsmoney,confersprestigebysucceedingovercompetitors,createsacclaim,andgenerates business opportunities. Competing is also a good way to compresstimescalesoftechnicalinnovationanddevelopment:towintheprize,achieve“x”by“y”time.

Although space entrepreneurs and experts often tout the value of prizes instimulatingnewtechnicalaccomplishment,theirefficacyinthefieldofspacetodatehas been less than impressive. The Annsari X-Prize for the first commercialsuborbital flightwaswon in 2004, but as of 2015, no other commercial suborbitalflight has taken place.16 Space businessmanRobert Bigelow establishedAmerica’sSpacePrize,a$50millionawardfor thefirstcommercialproviderof thetransportandreturnoffivehumanpassengerstoLEO.TheprizewasannouncedonDecember17, 2003, the hundredth anniversary of the first Wright Brothers flight, and itexpired in January 2010 without a single attempt to claim it. The GLEX was

announced in2007andhadadeadlineof2012,adeadline thathasbeenextendedtwice,firstto2014andthentotheendofMarch2015.Athirdextensiontotheendof 2017 was recently announced. I do not inventory these dismal statistics todisparage prize offers. Imerely point out that theyhave a poor record of creatingnewcapabilities.

Mostdiscussions about lunar resources focus almost exclusively on the technicalissuesassociatedwithextraction,transportation,anduse.Littlehasbeenofferedonthe legal issues involved in lunar or extraterrestrial mining—staking a claim, inother words, just as a miner does on Earth. This vacuum exists for a verystraightforwardreason:Nooneknows the legal statusof commercial spaceminingandplanetarysurfaceactivity.

Severalinternationaltreaties,themostpertinentofwhichisthe1967U.N.OuterSpace Treaty, set the current legal regime for space activities.17 Signed by 129countries, including all of the major spacefaring nations, the treaty bans nuclearweapons in space and prohibits any nation from establishing territorial claims onextraterrestrial bodies. This formulation left open the question of privatedevelopmentandownership,althoughthetreatystates,“Outerspace,includingtheMoonandother celestialbodies, shallbe free forexplorationandusebyallStateswithout discrimination of any kind, on a basis of equality and in accordancewithinternationallaw,andthereshallbefreeaccesstoallareasofcelestialbodies.”Notewellthelanguage:“freeforexplorationandusebyallStates.”ThatwordingwouldappeartoguaranteetherightsofanationtominetheMoon,extractaproduct,andthen—what?

Certainlyonewouldsupposethatthislanguageensuresthatagovernmentfacilitycouldmanufacturerocketpropellanttouseinitsownvehicles.Butdoesitpermitaprivatecompanybasedinthatnationtomakethesameproductandthenofferitforsaleontheopenmarket?CertainlytheFederalAviationAdministration(FAA)canissuerestrictionsonAmericancompaniesinregardtoimpingingupontheactivitiesofanotherAmericancompany—say, for example,MoonExpress landingavehiclenearaninstallationofBigelowAerospaceinflatablehabitatsontheMoon.Butwhoelse is obliged to observe those restrictions? International companies that launchfromtheirownsoildonotrequireFAAcommerciallicenses.Unlesssomereciprocalagreement is reached between all of thesenations, their private companies donothavetorespecttheaccessand“controlzone”rightsofothernations’companies.

Thesituationbecomesevenmurkierwhenconsideringthepossibleinteractionsofa private American company on the Moon and the national representatives of aforeignpower.SupposeanothercountrysuchasChinadecidedforwhateverreason

to land a government-funded, military-controlled spacecraft on a patch of lunarterritory that the FAA had previously set aside for the exclusive use of BigelowAerospace. Legally, the FAA license has nothing to do with China, which is notbound to observe any restrictions. When international relations are peaceful andproductive,conflictsareunlikelytoarise.Butpoliticalsituationschange,sometimesatthedropofahat,andcertainlyontimescalesshorterthanindustrialdevelopmentcycles.

Prime locations on the Moon, as on any other extraterrestrial object, are notlimitless,andaccesstoanduseofthemostdesirableandvaluablesitesforresourceprospectingandharvestingmaybecome contentious. In termsofwaterproductionfor rocket fuel and life support consumables, ideal sites are in zones of enhanceddurationsunlight(“quasi-permanentlylitareas”)neartheMoon’spoles,proximateto permanently shadowed regions and thus deposits of water ice. At such locales,electricalpowercanbecontinuouslygeneratedinordertoextractthenearbywaterice.Theremaybeonlyafewdozenzoneswhereinitialiceharvestingfacilitiesmaybeoperatedwithreasonableefficiency,onwhichmoreprospectingdatawillgiveusabetterpicture.Ifthisturnsouttobethecase,thenwhogetstherightstoproducetheproduct?Whatconstitutesstakingaclaim?Firstcome,firstserve?Ordoesmightmakeright?

Thisissueleadsustoconsiderthepresenceandroleofthefederalgovernmentinspace.Icontendthatastrongfederalpresenceinspaceisnecessarytoensurethatourrights are established and that our values are protected and promoted. In thehypothetical contextmentioned of Bigelow and Chinamentioned before, a singleAmerican company facing a determined nation-state is not likely to prevail in amannerfavorabletotheinterestsoffreemarketcapitalism.LegalrecourseonEarthwouldbelimited—morelikelynonexistent.ItisalsounlikelythattheUnitedStateswouldgotowarovertheinfringementofsomecorporateplotoflandontheMoon,at least during the early stages of commercial space. However, when the federalgovernment establishes a presence, it serves notice to the world that we havenationalintereststhere.Theirpresencemakesanyinfringementonthepropertyandaccess rights of American corporations less likely to occur in the first place—andmore easily resolved if such a situation arose, creating a much more favorableclimateforprivateinvestmentinspaceactivities.

Thereisnoreasontoassumethatallnationswillvoluntarilycooperateinspace,iffor no other reason than nations do not behave this way on Earth. Sometimesnational rights of way and access to resources must be guaranteed by a physicalpresence,backedupwiththreatofforce.ThisisthewayoflifeatseahereonEarth

andthereasonwehaveablue-waternavy—notonlytodefendourcountrybutalsotoprojectpowerandprotectournationalinterestsabroad.Historically,thenavyhasconducted exploration and goodwill tours in peacetime and power projection intimes of tension and war. A space navy could do likewise as humanity movesoutwardintothesolarsystem.

Ultimately,wewillneedtofaceuptoournationalandcollectiveresponsibilitiesto protect American commerce and interestswherever they reside.Given the costriskofopeningup space to commerce, companiesneedassurance thatgovernmentcan,andwill,helpprotecttheirinvestment.Intheverynearfuture,ourtheaterofoperations will include cislunar space. The idea that the private sector alone candevelopnearEarthspaceisnotrealistic,norevenadvisable.Itremainsadangerous,unpredictable world, and clear-thinking leaders need to plan for futureconfrontations,ifonly,sothattheycanbeavoided.Anydisplayofweaknesswillbeexploited—andnottoourbenefit.

I

9AVisittotheFutureMoon

believethecentral,near-termgoalfortheAmericancivilspaceprogramneedstobe a permanent return to the Moon. Once we do this, we create a new and

versatile spacefaring infrastructure, one capableof extendinghuman reachbeyondlow Earth orbit (LEO) into the solar system. If we eventually head in such adirection,whatmightweexpecttoseeinthefuture?Whatbenefitswillaccruefromthisdirectionandhowmight theydevelopover time?HereIenvisiona future forhumanityontheMoonandaseriesofstepsandeventsthataremostlikelytooccur,alongwith their appropriate implications.On theMoon,wewill begin touse andsettlespaceforavarietyofbeneficialpurposes.

EarlyActivitiesIn one sense, our lunar return has already begun through the series of roboticspacecraft that have mapped, measured, and surveyed the Moon over the pastdecade.Most of thesemissionswere orbiters, loadedwith a variety of sensors andinstruments designed to measure physical properties in almost every part of theelectromagnetic spectrum. These data, converted into maps showing shape, size,composition,andphysical state,havegivenusaclearerpictureof themakeupandevolutionofournearestneighbor.TheMoonisprobablythebest-mappedobjectinthesolarsystem,whilepartsofEarth’soceanflooraremorepoorlyknownthanthelunar far side. These survey maps allow us to evaluate the Moon as a planetaryobject.TheregionalinventoryofitsresourcesdeterminedfromorbitshowthattheMoon possesses what we need to create a new spacefaring capability. The LunarReconnaissance Orbiter (LRO) continues to give us the knowledge that fuelsresearchandproducesnewdiscoveries.

Impactors and landers have also added critical detailed information for small,selectedareasontheMoon.Oneofthemostimportantpiecesofinformationcamefrom the LCROSS impactor. In this mission, the upper stage of the LRO launchvehiclewascrashed intooneof thecold,darkregionsof the lunarsouthpole.Thecollisionwas observed by a small satellite that had followed the impacting upperstageandbytheLROspacecraft,alreadyinlunarorbit.Theejectedmaterialfrom

thisimpactconclusivelydemonstratedthatwatericeispresentwithinthiscoldtrap.Theamountisestimatedatabout7weightpercentatthislocation.Theejectaplumealso threw up other volatile species, including ammonia (NH4), methane (CH3),carbonmonoxide(CO),andsomesimpleorganicmolecules.1ThesedatasuggestthatthevolatilesoftheMoon’spolarregionsarelikelyofcometaryderivation.Withthisinformation, we can state with a strong degree of confidence that the materialsneeded for permanent human habitation on the Moon are present in the Moon’spolarregions.

WehavelocatedandquantifiedtheareasneartheMoon’spolesthatreceivethemost sunlight over the course of a year (figure 3.1). These lit regions are close todeposits of water ice and other volatiles. Maps produced by LRO and its orbitalcompanions will be crucial in locating likely sites for resource processing on theMoon.InadditiontothedirectsamplingoflunaricebyLCROSS,severaldifferentremotemeasurements support the presence of significant amounts of polarwater.The M3 spectral mapper on India’s Chandrayaan-1 spacecraft found evidence forhydroxylmolecules(OH)athighlatitudes(figure9.1),whichmigratepolewardtopossibly serve as a source for polarwater.2 A small impactor fromChandrayaan-1(theMoon Impact Probe) found a tenuouswater vapor cloud over the south pole(probablywatermoleculesenroutetotheirultimatesiteofdepositioninapolarcoldtrap).Mini-RFradarimagesshowhighdiffusebackscatterinsomepolarcraters(seefigure 5.1).Ultraviolet spectra and laser reflections indicate the existence ofwaterfrostonthesurfaceofthefloorsofsomepolarcraters.Neutronmeasurementsoverthe poles indicate extensive amounts of hydrogen. These data support ourunderstanding about the presence of significant amounts of ice at both poles, asmuchas10billiontonsateachpole.

Figure9.1.Schematicshowingthefivemodesofoccurrenceoflunarwater.Waterisfoundwithinmeltsformed

deepinsidetheMoonandsampledbyvolcanicglassesandminerals.Exosphericwateroccursasraremolecules

thatbounce around theMoon in the space just above the surface.Adsorbedwater is foundas amonolayer of

molecules on dust grains; these molecules increase in abundance with increasing latitude (decreasing mean

surfacetemperature).Surfacewaterfrostofmoresubstantialquantityisseenwithinthedark,coldareasnearthe

poles.Largeramountsofwatericemayoccurnearthepoleatshallowdepths(afewmetersorless)insubstantial

amounts(millionsoftons).(Credit9.1)

Despitetheabundantnewdata,inordertoachieveapermanentlunarpresence,wemustunderstandandmapthevariationsinpolarwatercontentonmeter-scales,laterally and vertically. The physical properties of the icemust be determined toplan forexcavationandwaterextraction.Wemust findareasof thehighestwaterconcentration that are closest to the areas of “quasi-permanent” sunlight, so as tomake future water processing most efficient. These properties and others can beobtained from additional robotic surface exploration. The ideal way to get thehighestqualitydataistolandanuclear-poweredsurfacerover,similartothecurrentMarsScienceLaboratory,andconductanextendedtraverseacrossthepolarregiontofindandmapoutthebestareas.3Identicallyequippedroversshouldbesenttoeachpole;althoughwesuspectthatbothnorthandsouthpolespossesssignificantvolatiledeposits, thescoutingofbothareasbytworoverswouldhelpusbecertainthatwelocatetheoutpostnearthehighestgradedeposits.

Shortofthisfairlysophisticatedlevelofexploration,aseriesofsmallermissionscould gather preliminary information on polar volatiles. One example of aninexpensivemissionistoflyapalletofaboutadozensmallimpactors(hardlanders)thatwouldbeindividuallydeployedandlandedtogathersurfacecompositionalandphysical data from multiple points. Although less desirable than the detailed,continuousinformationthataproperlyequippedroverwouldprovide,thisapproachmaybeagoodstrategytocollectwidespread,detaileddatainashortperiodoftimeforasmallamountofmoney.

Whenenoughprospectingdatahavebeenobtained,thenextmostpressingneedis to demonstrate the process of resource extraction and storage on the Moon.Although water extraction is probably the simplest processing of extraterrestrialmaterialsimaginable,inordertobetakenseriouslybysomeinthespaceengineeringcommunity, an actual end-to-end system demonstration is needed. Such a demomissioncouldbequitesmall;afixedlanderinthesunlight,fedwithfeedstockfromtheshadowedarea,couldheatthesoil,collectthewatervapor,liquefyit,andstoreit.Oncethisdemonstrationhasbeenaccomplished,theproductionoflargeamountsofwaterbecomesmerelyamatterofscale.

Some lingeringmysteries about the lunar surface environment also need to beaddressed. It has been postulated that the passage of the day/night line (theterminator)acrossthesurfaceinducesanelectricalcharge,oneofpossiblydangerousmagnitude.This effect couldbemeasured and that possible risk retired throughaseriesofmeasurementsfromafixedlanderoverthecourseofalunarday.Observingthepostulatedlevitationoffine-scaledustbyelectricalfieldsshouldalsobestudiedonthesurface,althoughevidenceobtainedrecentlyfromtheorbitalLADEEmissionsuggeststhatthisphenomenon,ifitoccursatall,isminorandoflocalextent.4

ConsolidatingOurLunarPresenceAspreviouslydescribed,Ibelievethatthemostefficientandleastexpensivewaytoreturn to theMoonwill require performingmuch of the preliminary, earlyworkwith robotic assets, followed later by people.5 In the early stages of lunar return,roboticmachines operated fromEarth can begin the harvesting and processing oflunarwater.WeshouldinitiallyplantobuildupenoughcapabilitytofuelareturntripbacktoEarthbeforehumansarrive.Suchacapabilityrequirestheproductionofabout100tonsofwaterperyear.Thisisn’tasgreataquantityasonemightimagine:100tonsofwaterisroughlytheamountcontainedinatanktheshapeofacube15feet (4.5 m) on a side, or roughly the volume of water in a single backyard

swimming pool. Because water is the most enabling resource with the widestpossiblerangeofuse,itisthefirstpriorityforutilization.

Significant mining activity on the Moon will require power and lots of it.Fortunately,thereisenoughsurfaceareainthepolarquasi-permanentsunlitzones(seefigure3.1)toestablishnetworksofmultiplesolararraypowerstations.Asinglestationcouldconsistofatall(~10–20m),narrow(~2–3mwide)arrayofsolarcellsthatcanbearticulatedarounditsverticalaxis(seefigure7.1)totracktheSunasitslowlymovesaroundthehorizonoverthecourseofalunarday.Suchanindividualstation would be low mass (~1 ton). As a modular system, these pieces could beconnected together to provide whatever level of power is needed. Initial roboticminingcapabilitywouldrequireroughly150kilowatts,powerthatcouldbeprovidedbyeighttotenindividualpowerstations.Asoutpostcapabilityandsizegrowsovertime, additional power stations delivered fromEarth can satisfy generating needs.Thispotentialforgrowthinasurfacepowersystemispossibleuptoabouttheten-megawattlevel,afterwhichwewouldprobablyneedtoconsiderthedeploymentofanuclear reactor. A thoriummolten salt reactor could be sized to provide virtuallyunlimited power (hundreds of megawatts) for a wide variety of uses and whileinitially supplied entirely from Earth, could ultimately be operated from locallyminedsourcesofthoriumontheMoon.

In civil engineering, one of the most important material resources on Earth is“construction aggregate”—the sand, gravel, and cement building materials thatmakeuptheinfrastructureofmodernindustriallife.Aggregateiseasilyoneofthemost importantandvaluableeconomic resourcesof allmined terrestrialmaterials,more so than gold, diamonds, or platinum. We depend on aggregate for manydifferenttypesofobjects;theyarethefundamentalbuildingmaterialsofroadsandstructures.Theuseofaggregateinbuildinggoesbacktoancientcivilizations,suchastheconcreteusedforconstructioninancientEgypt.TheRomansdevisedarecipeforaconcretesodurablethatthemoldedarches,walls,andself-supportingdomeofthePantheon,builtmorethantwothousandyearsago, still standtoday.Aggregates interrestrial use typically depend on a lime-based cement that bonds the particulatematerialtogether.Bothlime(CaO)andabundantwaterareneededtomakeconcreteonEarth.

By necessity, a permanent presence on theMoonwill require an infrastructurethat uses as much local material as possible. Aggregate materials probably willbecometheprimarybuildingblocksofindustrialsocietyoffplanet,justasithasonthe Earth. The composition and conditions of local materials will require someadjustments as to how we use lunar aggregate. A quick assessment reveals some

interestingparallels,aswellasdifferences,withterrestrialuse.OnEarth, gravel pits are carefully located to take advantage of the sorting and

layeringproducedbynaturalfluvialactivity.Weharvestgravelsfromalluvialplainsandold riverbeds,where runningwaterhas concentrated rocks, sand, and silt intodepositsthatcanbeeasilyexcavated,loaded,andtransportedtositesofconstruction.The highly variable currents, as well as the velocities of flow of our terrestrialstreamsandrivers, sort theaggregatebysize.Thisnaturalsortingcreates layersofgravel-tocobble-sizedstonesforthefastestflowingwaters.Finer-grainedmaterialislikewiseconcentratedwherewaterspeedsarelow,andsandandsiltsettlesoutfromthesuspendedsediment(the“bedload”).

UnliketheaggregateprocessingbywateronEarth,lunarsurfacerockhasalreadybeendisaggregatedintoachaoticuppersurfacelayer(regolith)byimpact.Regolithisground-upbedrock; impactingobjectsofall sizesconstantlypummelthesurface,breaking, fracturing,andgrindinguptheMoon’sbedrock,aprocessof impact thathasgreatlyslowedfromthemuchhigherlevelexperiencedearlierinlunarhistory.The regolith is a readily available buildingmaterial for construction on the lunarsurface.ItisanaggregateinthesamesenseasonEarth,butwithsomesignificantdifferences.Wecouldmake limeandwater fromtheMoon’s surfacematerialsbutthatwould require toomuch timeandenergy.Thus,we shouldadapt andmodifyterrestrial practice to take advantage of theuniquenature of lunarmaterials.Thefractalgrainsizeintheregolithmeansthatwecanobtainanyspecificsizefractionwewantthroughsimplemechanicalsorting(rakingandsieving).Insteadofwater-set, lime-based cement,we can use the glass in the regolith to cement particulatematerialtogether,thatis,sintertheaggregateintobricksandblocks,aswellasroadsand landing pads, using thermal energy (figure 9.2). Both passive solar thermalpower (concentratedby focusingmirrors) or electricallygeneratedmicrowaves canprovidetheenergytomeltgrainedgesintoahard,durableceramic.

Figure9.2.Roboticrovercarryingmicrowavesinteringequipmenttofuselocalregolithintoceramicpavement

foruseasalandingpadforspacecraft.Powerformeltingthesoilisprovidedbysolararrayatcenter.(Credit9.2)

Theuse of aggregate on theMoonwill likely be gradual and incremental.Ourinitial presence on the Moon will be supported almost entirely by materials andsuppliesbroughtfromEarth.Aswegainexperienceinusinglunarresources,wecanincorporate localmaterials into the structures. Simple, unmodified bulk soil is anearlyusefulproduct.Itcanbeusedinbuildingbermstoprotectanoutpostfromtherocket blast of arriving or departing spacecraft, and to cover surface assets forthermal and radiation protection. The next phase will be to pave roads andlaunch/landingpads to limit theamountof randomly throwndust and toprovidegood traction for a multitude of wheeled vehicles supporting the outpost. Thefabricationofbricksfromregolithwillallowustoconstructlargebuildings,initiallyconsisting of open, unpressurized workspaces and garages, but ultimately habitatsandlaboratories.Thenewtechnologyofthree-dimensional(3D)printingwillallownearly autonomous machines to construct the lunar outpost through the use ofregolithaggregateassembledintostructuresby3-Dprintersworkinginconjunctionwith Earth-controlled construction robots.6 Making glass by melting regolith canproduce building materials of extreme strength and durability; anhydrous glassmadefromlunarsoilisstrongerthanalloysteel,withafractionofitsmass.

MetalsareabundantintheMoonandcanbeextractedfromthelocalmaterials.The basic process is one of simple chemical reduction, accomplished through avariety of low-tech processes, all of which were known to eighteenth-centuryindustry.Carbothermalreductionofilmenite,anironandtitaniumoxide,hasbeendemonstratedinthelaboratorytoproduceoxygen;italsoproducesnativemetalasaby-product.Theuseof fluorinegasasareducingagenthasalsobeenwell studied.Metal production techniques require large amounts of electrical power, as it takessignificantenergytobreakthetightmetal-oxygenbonds incommonrock-formingmineralstructures.Forthisreason,itislikelythatmetalproductionwillcomelateinlunar industrialization; initial surface structures and base infrastructure pieces arelikelytobemadefromlower-energyproducts,likecompositesandaggregate.

AlthoughmostproductsmadeontheMoonwillbeusedlocally,eventuallywecanexport lunar products into space.The gravitywell of theMoon is a drawback forlargemassdelivery—its escapevelocity is about2.38kilometersper second,muchsmaller than that of Earth (11.2 km/s), but still substantial. In order to use largequantities of lunar materials for space construction, we need to develop aninexpensivemeanstogetmaterialoffitssurface.Fortunately,theMoon’ssmallsizeandlackofatmospheremakethispossiblebybuildingasystemthatliterallythrowsmaterialofftheMoonintospace.A“massdriver”canlaunchobjectsoffthelunarsurfacebyacceleratingthemalongarailtrackusingelectromagneticcoilsthathurlencapsulatedmaterialintospaceatspecificvelocitiesanddirections.7Wecancollectsuch thrownmaterial at a convenient location, such as one of the librationpoints.From there, it is a relatively simplematter to send thematerial towherever it isneededincislunarspace.Amassdriverisnotascience-fictionconcept;suchsystemsareusedtolaunchplanesfromtheflightdecksofaircraftcarriers.8

SurfaceActivitiesandExplorationAnearlygoalforlunarreturnistobecomeself-sufficientintheshortestamountoftimepossible.Thisdoesnotmean thata significantamountof surfaceexplorationand science is not also attainable. By virtue of being on the Moon for extendedperiods, we will have many opportunities to study lunar processes and history inunprecedented detail. Our scientific tasks include understanding the nature anddetails of the regolith and its interaction with the space environment (a topicaddressable any place on the Moon). Such study has both practical relevance, tobetter conduct resource processing and to improve product yield, and academicinterest,sincedetailsofregolithdynamicsremainelusive.Anexampleofasimple,

easy-to-completeexperimentistodigatrenchintheregolithseveralmetersdeep.9Intheexposedwallofthistrenchwouldbeseveralbillionyearsofsolarandimpacthistoryavailableforourinspection,sampling,anddetailedstudy.

TheMoonhasexperiencedtheprocessesofimpact,differentiation,volcanism,andtectonism. These processes occur on all rocky planets in the solar system. Theantiquityofthelunarsurfaceensuresthatnear-completeexamplesoftheseprocessesare on display for our enlightenment. By using theMoon as awindow into earlyplanetary history, we improve our understanding not only of its history andevolutionbutalsothehistoryandevolutionofalltheplanets.Asoneexample,theEarth and Moon have occupied the same volume of space for the last 4.5 billionyears,aspacewheretheimpactfluxaffectsbothobjects.AsaresultofEarth’shighlydynamic surface environment, these ancient events have not been preserved.However, the lunar surfacepreserves the impact recordof theEarth-Moon systemdatingbacktoatleast3.8billionyearsago.Thestudyofamultitudeoflunarcraterscan tell us about changes in the impact rates over time, a topic relevant to theextinctionandevolutionoflifeinthegeologicpast.

A common article of faith in many academic and space circles is that roboticspaceflight is the preferred method of scientific exploration. Many famous spacescientists, includingJamesVanAllenandCarlSagan,arguedfor thesuperiorityofunmannedmissions overhumanones. Indeed,manyphenomena in space, such asplasmas and magnetic fields, cannot be sensed directly by humans, and in somecases, such as detecting the tenuous lunar “atmosphere,” the presence of peopleinterferes with the property being measured. I agree that while some scientificactivitiescannotorshouldnotbedonebypeople,inotherareas,ahumanpresenceisnotjustbeneficial—itiscritical.

TheMoonisanaturallaboratory,aplacewhereimportantscientificquestionscanbe answered. The conceptual visualization of the four-dimensional—three spatialdimensions plus time—makeup of planetary crusts is achieved through fieldwork.Fieldworkisnotmerelyamatterofpickinguprocksortakingpictures.The“field”istheworldinitsnaturalstate,wherethephenomenawestudyareondisplayandwherewe observe facts and clues that permit us to reconstruct past processes andhistories.

A good example of the difference in capabilities betweenhumans and robots isillustratedbytheexperiencewiththeMarsExplorationRovers(2003–present).Overthe course of their first five years on Mars, these machines traversed manykilometersofterrain,examinedandanalyzedrockandsoilsamples,andmappedthelocalsurface.Theseroboticrovers,givingusanunprecedentedviewofthemartian

surface and its geology, have returned many gigabytes of data. They are trulymarvelsofmodernengineering.Yet,afterallthisextended,roboticexploration,weareunabletodrawasimplegeologicalcrosssectionthrougheitherofthetwoMERlandingsites.Wedonotknowtheoriginofthebeddedsediments,strikinglyshownin the surface panoramas; we do not know whether they are of water-lainsedimentary,impact,origneousorigins.Wedonotknowthemineralcompositionofrocks forwhichwehave chemical analyses.Without this information, theplanet’sprocessesandoriginscannotbedetermined.

EvenaftermorethanadecadeofMarssurfaceexploration,westilldonotknowthings about the field site that, given an afternoon’s reconnaissance, a humangeologistcouldhavededuced.Incontrast,wehaveanincrediblydetailedconceptualmodel,albeitincomplete,ofthegeologyandstructureofeachofthehumanvisitedApollolandingsites.ThelongeststayontheMoonforthesemissionswasthreedays,mostofwhichwasspentinsidetheLunarModule.

A robotic rover canbedesigned to collect samples, but it cannot bedesigned tocollectthecorrect,relevantsamples.Fieldworkinvolvestheposingandansweringofconceptualquestionsinrealtime,whereemergingmodelsandideascanbetestedinthefield.Itisacomplexanditerativeprocess;geologistscanspendyearsatcertainfield sites on the Earth, asking and answering different and ever more detailedscientific questions. Our objective in the geological exploration of the Moon isknowledge and understanding. A rock is just a rock—a piece of data. It is notknowledge.Robotscollectdata,notknowledge.

Becausepeoplecontrolplanetaryexplorationrobotsremotely,ithasbeenarguedthathumanintelligencealreadyguidestherobotexplorer.HavingdonebothtypesoffieldexplorationonEarth,Icontendthatremote,teleoperatedroboticexplorationis no substitute for being there. All robotic systems have critical limitations—important sensoryaspects, suchas resolution,depthof field, andperipheral vision.Robots have even greater limitations in physicalmanipulation. Picking a sample,removing some secondary overcoating, and examining a fresh surface is animportantaspectofworkinthefield.Thephysicallimitationsofteleoperatedrobotsare acceptable in repetitive, largelymechanicalwork, such as road construction ormining,but increative, intellectualexploration theyarewoefully inadequate.Themakers of the MER rovers recognized this need by including an abrasion tool tocreate fresh surfaces; regrettably, it becameworndownandunusable after a shortperiodofoperation.

Ultimately,weneedbothpeopleandmachines,eachwiththeirownappropriateskillbasesand limits, toexplore theMoonandotherplanets.Machinescangather

early reconnaissance data, make preliminary measurements, and do repetitive orexhaustive manual work. Only people can think. And thinking, and then takingactionandworkingwiththoseinformedresultsinrealtime,iswhatfieldworkisallabout.

OntheMoon,wewilllearnmoreabouttheuniverse,andbydoingso,wewillalsolearnhow to study the universe.Recognizing that people and robots bring uniqueandonlypartlyoverlappingcapabilitiestothetaskofexploration,wemayfindthata combined, specialized approach that builds upon the strengths of both, and thatmutuallysupportstheweaknessesineach,isthemostefficientandbeneficialwaytoexplore.10Itiseasytoconductthoughtexperimentsinhowtelepresentrobotscouldreplacepeopleonplanetarysurfaces,butwehavenorealexperienceinusingthem.By experimentingwith these techniques on theMoon,we can learn the optimumapproach for specific exploration tasks. Simple reconnaissance may be conductedwithminimalhumaninteraction,butdetailedfieldstudymightrequirecontinuous,real-time human presence. Knowledge of the problems appropriate for eachtechnique is something that can be acquired and understood on the Moon. Suchunderstandingisvitaltofutureexplorationandforcomprehendingotherplanetaryobjects.

BuildingaTransportationInfrastructureIncontrasttothe“build,launch,use,throwaway,thenrepeat”paradigmofthepast,we seek to create a permanent spacefaring infrastructure that incorporatesreusability for as many assets as possible. Although much of the current focus inspacedevelopmentisonreusablelaunchvehicles,reusabilityisactuallymucheasiertoachieveforvehiclesthatarepermanentlybasedinspace.Thesespacecraftdonothavetoundergothethermalandmechanicalstressesoflaunchandreentry.Cislunartransportationconsistsofmultiplesteps,includingthemarshalingofassetsatcertainpoints, such as rendezvous and preparation in LEO and L-points (see figure 9.3)followed by transport to the next marshaling area (involving a rocket burn toincreaseordecreaseorbitalenergy).Sincetheseactivitiesputlittlestressonvehiclesystems,thereisnotechnicalreasonnottodesignasmuchreusabilityintothemaspossible.

Figure9.3.DeepspacestagingnodelocatedatEarth-MoonL-1,about60,000kilometersabovethecenterofthe

lunar near side. A staging node can serve as the jumping-off point formissions to theMoon and planets; it

contains ahabitat for temporary layovers and apropellant depot for the refueling of spacecraft.FutureOrion

spacecraftshowndockedtothetransportnode.(Credit9.3)

Inthelunararchitecturedescribedpreviously,Icallforthebuildingofa30-ton-classreusablelunarlander(seefigure7.1).Thepurposeofthisvehicleistotransportpeopletoandfromlunarorbit.Byeliminatingtheneedforextendedlifesupport,wecan make this vehicle smaller than the proposed Altair lander called for by theConstellation architecture. Here, the issue of reusability largely revolves aroundengineperformanceandmaintenance.AthrottleableversionofthevenerableRL-10cryogenic engine, used today in the Centaur upper stage, can perform multiplerestartsandisagoodengineonwhichtobasethecreationofareusablelander.Atsomepoint,wewillhave to changeout engineson the reusablevehicles,but theycan be made part of a modular system serviceable by suited astronauts andteleoperatedmachines on the lunar surface. A reusable landerwould spend abouthalfofitstimeontheMoonandtheotherhalfinspace,attheappropriatestagingnode, either in low lunar orbit or at one of theL-points. Itwould be designed toreachitsspacenodewithhalfofitsfuelremaining.Thispermitsthelandertomakethe next descent and landing and then refuel on theMoonwith propellantmadefromlunarwater.

Passive, space-based assets require much less work to maintain. Staging nodes,wherevehiclescanmeetandinteracttotransfercrew,collectcargo,refuel,andthelike, will become part of the transportation system. These nodes are actuallyminiature space stations, complete with their own power, thermal, and attitudecontrolsystems.TheyaremuchlesscomplexthantheISS,inthattheyaredesignedonlyforasinglespecializeduseandareunoccupiedmostofthetime.However,somemaintenance will be needed to keep the nodes functioning correctly. This mayincluderefuelingtheattitudethrustersandmaintainingtheelectricalandthermalcontrolsystems.Transportnodescanbebasedinseverallocalities,includingLEO,anL-point,andinlowlunarorbit.Thenodesmayormaynotbeassociatedwithafueldepot.

AnorbitingfueldepotisanewtechnologythatcanincreasethesizeofpayloadsplacedontheMoonandthroughoutcislunarspace.However,wehavemuchtolearnabouttheirconstructionandoperation.Thebiggestdifficultyislearninghowtodealwiththe“boil-off”ofextremely lowtemperaturecryogenic liquids.Liquidoxygenboils at —183°C, and liquid hydrogen boils at —253°C. Although we can shieldstorage tanks from direct exposure to solar illumination with screens, passivethermal radiation from the depot itself will heat these liquids enough to causeevaporation.Thisproblemmustbesolvedtocreateapermanentspacetransportationsystem. Althoughwe do not know how tomitigate this issue at themoment, thesolutionwill probably involve capturing the boil-off gases and recondensing themintoliquid.

Onewaytominimizelossfromboil-offistokeepthepropellantinamorestableform until it is actually needed. We can transport propellant throughout cislunarspaceintheformofwater,asubstancethatiseasilystoredandtransferred,andthencrackedintothecryogensjustbeforeaspacecraftisscheduledtoarrive.Thiswouldrequirethatthefueldepotsofthefuturealsocontainapropellantprocessingsystem.Such a system would include large solar panels, cryogenic plants, and storagefacilities.Withthiscapability,thefueldepotbecomesamorecomplexspacestation,but it also decentralizes operations throughout the entirety of cislunar space.Notethatwewill still need these cryogenic processing facilities on the lunar surface inordertorefuelarrivingspacecraft,alongwiththeirobviousimportancetothecrewswholivethere.

AcompletecislunartransportationsystemconsistsofanEarthtoLEOtransport,multiplestagingnodes,fueldepots,transitspacecraft,landers,andthelunaroutpost.SuchasystempermitsroutineaccesstotheMoonandtoallotherlocationswithinandthroughoutcislunarspace.Forthefirsttime,wewillbeabletomovepeopleand

cargo where they are needed, anywhere in cislunar space. Currently,communicationssatellitesatGEOareinaccessibleforvisitsbypeople.Withthenewsystemdescribedhere,wecantraveltoGEOtorepair,maintain,orevenbuildnewdistributed satellite systems of unprecedented power and capability. Acommunications satellite the size of the ISS could provide uninterruptedcommunications coverage over a hemisphere, rendering the entire terrestrial cellphone network obsolete in an instant. It could provide enough bandwidth toaccommodate thousands of channels of high-definition video, Internet traffic, andpersonalmessaging.Three such complexeswould link the entireworldwith thesecapabilities; it would generate new wealth and provide endless possibilities forinnovation and technology development. In addition, we will be better able toprotect sensitive surveillance equipment and other strategic assets. Such capabilitywillmake theworld safer, in thatwewouldnotberenderedblind in theeventofaggressionandwecouldbetterrespondtocrises,bothnaturalandman-made, thatmaydeveloponEarth.Theupgradingandenhancementofscientificsensorswouldalso be possible, including such difficult tasks as the servicing of the soon-to-be-launchedJamesWebbSpaceTelescope,tobelocatedattheSun-EarthL-2pointandinaccessibletoservicingspacecraftwithexistingsystems.

Ibeganthisacademicjourneybyexplaininghowwecanuselunarmaterialandenergyresourcestocreateanewspacefaringcapability—thecreationofapermanenttransportation infrastructure in space. Such a capability can satisfy all of ourrequirements tomaintainandenhance service satellites, and toopenup theMoon(and indeed, theentire solar system) forexplorationanddevelopment.The restofthejourney—theonethatyoumayenvision—isnowpossible.

ExportsfromtheMoonUntilnow,IhavemainlyfocusedonthedevelopmentoflunarresourcestoobtainafootholdontheMoon,but is thereanythingontheMoonthathaseconomicvalueelsewhere, other than at a lunar outpost? What lunar exports might becomeprofitableinthefutureandhowmightsuchmarkets,betheyprivateorgovernment,bedeveloped?Istherea“killerapp”inlunarresources,aproductorservicethatcancreatenewwealthandactuallygiveusareturnonourinvestmentinspaceflightandinfrastructure? Many people and nations are keenly aware of the possibilities torealizeaprofit,andareconsideringwaystoexploitanadvantage.

The most obvious lunar product of economic value is water. As previouslydescribed,waterisanextremelyusefulsubstanceinspace:Itcansupporthumanlife,

it serves as a medium for energy storage, and it can be used to make rocketpropellant. Thus, for spacefaring nations and companies, by having the ability topurchase useable water already in space, it negates the requirement for them tobring water along from Earth. This option makes their space missions moreproductive,moreroutine,andmoreprofitable.Aspace-basedmarketforwaterwillprobably emerge first. Special importance will be given to the availability ofpropellantattheorbitalfueldepots.Agoodpolicywouldbetohusbandanysurpluswateratfueldepot-transportnodesforsaleorbarterwithotherspacefaringnations.Such fuel sales could be used to support the flights of other countries on theircislunarmissions.Itwillalsofinduseasfuelforattitudecontrol-orbitalmaintenancethrusters.Atthemoment,suchthrustersusestorablepropellant,butifaspace-basedsourceforcryogensbecameavailable,thesatellitebuildersoftheworldwouldsoonmodifytheirsystemstoenableitsuse.

TheideaofgeneratingelectricalpowerinspacefortransmissionbacktoEarthtobesoldcommerciallyhasbeenastapleoflunardevelopmentschemesforsometime.TheSolarPowerSatellite(SPS)concepthasalwaysfacedamajorstumblingblock;thehigh cost of launch fromEarthof themassive solar arraysmake it financiallyinfeasible.11Apermanentpresenceon theMoonchanges thatpicture.Solararrayscanbemanufacturedfromlunarsurfacematerialsandlaunchedintocislunarspaceat lower cost, due to the lower gravity of the Moon.12 In fact, it is likely that iffinancially viable SPS systems ever become available, they will be made possibleonlythroughtheuseoflunarresources.

AnextremevariantofthisideaproposestomakethesolararraysinplaceontheMoon.A small rover rollsalong theground, fabricatingamorphous solar cells thatareconnectedandwiredtogetherastheroverslowlymovesacrossthelunarsurface,manufacturing a solar array that can be tens to hundreds of square kilometers inextent. In the equatorial zones of the Moon, gigantic solar panels farms, withenormousgigawatt-levelpoweroutput,cantransmittospaceordirectlytoEarthvialasersormicrowaves.Receiversineitherlocationcancollectthispowerandofferitat commercially competitive rates. To receive constant solar illumination, thissystemwould require the construction of two solar array farms on the equator onoppositesidesoftheMoon.Seeminglysomethingfromsciencefiction,ifundertakenat the appropriate scale, such energy production on the Moon (which has beenanalyzedeconomically)isworkable.13

Thepossibilityofextractinghelium-3fromthelunarsoiltopowerfusionreactorson Earth for commercial power generation may be possible within the next fewdecades,onceadeterminationismadewhethersuchaplanis technicallyviableor

not.14 If so, helium-3 mining could be a competitor to large-scale solar powergeneration on the Moon. It would require a significant amount of surfaceinfrastructuretoproducecommerciallyusefulquantitiesofthefuel.Onewildcardinthehelium-3storyisthatwedonotknowhowmuchofitmightbecontainedinthepolar cold trap volatiles. If these volatile substances are of cometary origin—andanalysisoftheLCROSSdatasuggeststhattheyare—helium-3mightbepresentatroughly solar abundance.15Thus, it could be easier and less costly to extract largeamountsofhelium-3 frompolar ice, than fromequatorialmare regolith.This is amissing piece of information that will be answered once we are able to send aproperlyinstrumentedroverintothepolardarkareasontheMoon.

Otherlunarproductsmayeventuallybecomeeconomicallyattractive.Wearenotimaginative enough to envision them all. The earliest product to have monetaryvaluefromexportcomesfromthefirstproductthatwemakeontheMoon—water,inallofitsforms.Tomovethroughspacerequirestheexpenditureofenergyintheformofrocketfirings.Thus,thefreedomofspaceisenergychange.Energychangeisa rocket firing. Rocket firings require propellant. To make propellant, we needwater.AndwaterisavailableinlargequantityfromthepolarcoldtrapsoftheMoon.Thus, water is the currency of spaceflight. By establishing a resource processingfacilityontheMoon,wepositionourselvestoparticipateintheworldmarketsofthefuture.

LearningtoLiveandWorkonAnotherWorldSeveralskillsmustbemasteredandmanydifferenttechnologiesmustbedevelopedifhumanityistobecomeamultiplanetaryspecies.Onerecommendationofthe2009AugustineCommitteewastotablethenotionofselectingdestinationsinspacesuchas the Moon or Mars and instead work on developing the technology to goanywhere.16Then,whenwehavethetechnologynecessary,werampupandgototheplanets.Thisapproach,calledthe“FlexiblePath,”wasquicklyembracedbytheadministrationthatcharteredthecommittee.AdoptionoftheFlexiblePathwasanattempttodistractnationalattentionfromthefactthatourcivilspaceprogramwasgoingnowhere.

Thelargestandmostcomprehensiveexpansionofspacetechnologyinhistorywastheproductof theApolloprogram, theantithesisofa“no-destination”effort.Thetruthis,wegetmoretechnologydevelopmentasaresultoftheneedtosolvespecificproblems,problems that arisewhenwe try todo somethingorgo to someplace inspace. Confronted with specific issues and needs, technical solutions must be

developed or we go nowhere, learn little, solve nothing, and become vulnerable.Historically,apressingneedforanswersdrives innovationmuchmorequicklyandefficiently,thandoestinkeringaroundinahobbyshop.

WegototheMoontolearnhowtousewhatithastooffer.Oneofthoseofferingsis its virtue as a world on which to live and work. Humans have almost noexperiencewith this. TheApollomissions fifty years ago allowed a few people toexperience the Moon for a few tens of hours each. From that experience came adreamthathasneverfaded:thatagreatadventureandfutureawaitsthefirstpeoplewho attempt tomake life in space an extended experience.TheMoon is our firststep. The struggles humans will face learning to survive in a hostile, foreignenvironmentaredifficultiesweneedtofaceandsolvebeforeweventurefurtherintothesolarsystem.LearninghowtoliveandworkontheMooninvolvesbothhumansand machines, together, coping with an environment of low gravity, vacuum,thermal extremes, and hard radiation. We can design equipment to use and toprotectusforshortdurations,butweneedtounderstandhowwelltheseinstrumentsandmachinesworkontimescalesofmonthsandyears.UsingtheMoonasanaturallaboratorywillteachushowtoarrive,survive,andthriveonotherworlds.

Besidessurvival,wealsoneedtolearnhowtoexploreandstudyalienworlds.Wehaveavagueideathatsuchanexplorationtemplatesomehowinvolvesbothhumansand robots, but how do they interact and work together and apart to yield themaximumbenefit?As spacedestinationsandobjectivesbecomemorecomplexanddangerous,itmakesgoodsensetousetheMoontolearnhowtoproperlyconducttheseriousbusinessofexploration.Humansyearntoexplore.Bydoingso,theyacquirestrategic knowledge that increases our odds for survival. Making new discoveriesbroadenstheimaginationandallowsustoenvisionsolutionstoproblemsthatmightotherwisenothave occurred tous.Practical experience on theMoonwill serveuswellaswebeginhumanity’smovementintotheuniverse.

M

10WhereDoWeGoFromHere?

anyofusworkinginorwithNASArecognizedthatthe2004VisionforSpaceExploration (VSE) was a conceptual breakthrough. The goal of using off-

planetresourcestoenablenewcapabilitiesinspaceflightwasthefulcrumweneededtochangeourapproachanddirectiontospaceflight.Makingthischangewouldopenthedoortoawidevarietyofpreviouslyunobtainablemissionconceptsandideas.

In this book, I have shared my perspective on why and how the VSE wasconceived,executed,andeventuallyterminated—acautionarytale,ifyouwill,butIhopeaninstructiveone.LessonsdrawnfromthishistorycankeepusfromrepeatingsimilarmistakesandhelpuscreateabetterAmericanspaceprogram,onethatmoveshumanityintothesolarsystembycreatingnewopportunitiesandexpanding,ratherthanconsuming,wealth.

BecauseNASA’sresponsetotheVSEwastofocusonthefirsthumanmissiontoMars, they devised an Apollo-style architecture, reverting to the only successfuloperationaltemplateforplanetaryexplorationwithwhichtheagencywasfamiliar.Thisdecisioneffectivelyderailed the incrementalandsustainableapproachfor theextensionofhumanreachintospace,intendedbytheVSE.AnApollo-stylemissionto Mars remains a bridge too far fiscally, technically, and politically. TheinterpretationofahumanMarsmissionas thecentralgoal for theagency ignoredthe consideredwork of the VSE architects and those of us who hadworkedwithNASA in the immediate years following its announcement. Certainly I was notinterestedinparticipatinginanew“MissiontoMars”paperstudythatwasdoomedtofailurefromthebeginning.Manyofushadalreadyexperiencedthisduringtheyearsof theSpaceExplorationInitiative (1989–92),anearlierattempt to re-createtheApollozeitgeist.

TheexcitementthatmanyofusfeltatthebeginningoftheVSEcamefromthebeliefthatthoselessonsaboutwhatdidnotworkhadbeenwelllearnedandthatalong-overdue change in the templateof spaceflightwasuponus.We soonbecamedisabusedofsuchanotion.Althoughmanyinthespacecommunityunderstoodboththepossibilitiesandthepitfallsoftheneweffort,thedominantcultureinboththeagency and industry was wedded (and remains wedded) to the old template. AsNASArevertedto theircomfortzone,boththe impressionandthereality that this

wasabout“repeating”ourpreviousexperiencewiththeMoon—toregainthegloryofApollo—wascementedinmanyminds.ThismindlesscalculusbrandedthelunarsegmentoftheVSEwitha“beenthere,donethat”label, leadingtotheinevitablecharacterizationthattheMoonwasbotholdhatandanunaffordabledistraction.

GiventhatNASAwashandedanewandchallengingmissiontogototheMoonon twoprevious occasions, theSEI in1989and theVSE in2004—andboth timestheydroppedtheballonimplementingit—onemightimaginethatanewentityisneededtoconducthumanspaceflightforthefederalgovernment.Thisconcepthasnot gone unvoiced by the community; no less an authority than Harrison “Jack”Schmitt,Apollo17astronautandthefirst(andfornow,thelast)scientisttoexplorethe Moon, has proposed that NASA be abolished and that a new agency beestablished to implement a long-range, strategic plan for human spaceflight.1Schmittwould reassign someNASAactivities (aeronautics research, astronomy) toother agencies and retain within the new entity only the field centers critical tohumanspaceflight.Thenewspaceagencywouldtakeoverexistinginfrastructureforthese functions and maintain a minimal headquarters presence in Washington topresideoverpolicydecisions.

IsympathizewithSchmitt’sfrustrationattheobtusenessandintransigenceoftheexisting agency, but I think that his reformulation idea, while having much tocommend it, is unlikely to be realized under normal circumstances. Too manyentrenchedinterests,politicalaswellaslocal,wouldbeaffectednegativelybysuchamajor reconstitution. However, some institutional crisis of confidence, a series ofdisasters or evidence of massive incompetence could produce the politicalmomentumforradicalchange.ThishashappenedinNASA’spast—theApollo1firein1967resultedinawholesalehousecleaningofatleasttheuppermanagementoftheApolloprogram,andtheChallengeraccidentin1986likewisecausedmuchsoul-searching.The series ofblunders in theearly1990s involving the faultymirrorofthe Hubble Space Telescope and failure of two Mars missions led to calls for anagencyshakeup.Eachtime,NASAwasabletoshrugoffanysignificantinstitutionalimpacts,butinthemidstofsomefuturedisaster,theirbureaucraticluckmayfinallyrunout.However,thenationalmoodseemsprimedlatelytodemandaccountabilityinourgovernmentinstitutionsandelectedofficials.Suchapolicyenvironmentmayyetresultinamajorreconfigurationofthecivilspaceagency.

Flights to supply the International Space Station (ISS) using non-NASA“commercial” spacecraft areportrayedas anewgoal anddirection for space, eventhough the development of these new vehicles has been and will continue to belargely billed to the American taxpayer, aswill be true of their operational costs.

These days, transporting our astronauts to the ISS, the space station that weprimarily designed, built, and paid for, requires thatwe pay the going rate to flyaboardaRussianSoyuzspacecraftorstayhome.Wefindourselvesintheuntenablesituation ofhaving a dysfunctional spaceprogramwithno strategic direction.Ournation’sdirefinancialsituationisrapidlyapproachingcrisisproportions.Itishighlylikely that futurespacebudgetswillbe flatatbest,butmoreprobably, lower thancurrentlevelsoffunding.

Our current program direction, the promise of a human Mars mission—as yetunachievable, but perhaps doable 25 to 30 years down the road—remains theprincipal roadblock to implementing aworkable programbased on theuse of off-planet resources. It doesn’thave to be. It is highly likely thatwewill achieve ourfirst humanmission toMars only through the use of propellant produced on theMoon.2TheMoonhasmuchmore to offer, both as a testingground for advancedplanetarysurfacesystemsandasanaturallaboratorytolearntheskillsrequiredforanewgenerationofplanetaryexplorers.ArealisticarchitectureforMarsincorporatesandutilizesthevaluableresourcesoftheMoon.

ThosewhobelievethatweshouldproceeddirectlytoMarsandbypasstheMoonmightconsiderthefollowing.MartiangravityistwiceasstrongastheMoon’s.Withaerobraking,delta-vtothesurfaceofMarsisroughly1000m/s,andascenttoorbitfrom the surface is about5000m/s.Thismeans that youmustbringanascent ordescentmodulewithyoutoMars;ifyouweretogotoMarswiththeintenttosettlethere, itwouldperforcebeaone-waytrip.OntheMoon,werequireroughly2000m/sup or down.This canbe accommodatedwith a single-stage vehicle,meaningthatwecanreusethisspacecrafttoenablecontinualtravelbetweenlunarorbitandthesurface.Reusabilityenablesanaffordablesolutiontotheproblemofestablishingan off-planet presence; travel back and forth to the surface coupled with anincrementalbuildupoftheoutpostontheMoonmakesthecreationofapermanentpresence therepossible inamanner that isnotpossibleonMars,wherediscarded,once-usedpiecesresultinanexpensive,unsustainabletransportationarchitecture.

Thecurrentspaceflighttemplateestablished60yearsagoistocustom-designandbuild spacecraft, then launch them on expendable vehicles: design, build, fly, use,and discard. Born of necessity, this operational model ensures that spacecraft arecomplex, expensive, and serve a limited lifetime. It demands that we launcheverythingweneedfromEarth—fromthebottomofthedeepestgravitywellintheinnersolarsystem—requiringsignificantenergy(read“cost”)toreachanintendeddestination.Untilwechangeournationalapproachtotheproblemofspaceflight,wewill remain mass-and power-limited, and therefore capability-limited in space.

These necessary, expensive, and difficult goals are achievable under constrainedbudgetsbytakingsmall,affordable incrementalsteps thatbuildoneachotherandworktogethertocreateagreatercapabilityovertime.

NearlyallofourmodernspaceassetsresideinthezonebetweenEarthandMoon(cislunar space) and the difficulty of reaching low Earth orbit (LEO) limits ouractivitiesthere.Thesecislunarsatellitesconstitutethebackboneofmoderntechnicalcivilization and conduct critical societal functions such as communications,positioning,remotesensing,weathermonitoring,andnationalstrategicsurveillance.Thesizeandcapabilityofsuchassetsarelimitedbythesizeofthelargestrocketthatcan launch a given payload and by their preordained operational lifetime. OurexperienceworkingwiththespaceshuttleandISSprogramshasdemonstratedthatpeopleandmachinesworkingtogether,overtime,canassembleandmaintainspacesystemsthatcanbemadeaslargeandoperatedforaslongasdesired.Theproblemismovingpeopleandrobotstothesevariouspointsincislunarspace.

To become a spacefaring species, we must develop and possess freedom ofmovement and action, throughout cislunar space. Robotic missions show that theMoon’spolescontainsignificantamountsofwaterice,themostuseableresourceforhumans in space.Asa consumable,H2O(waterandoxygen) supports life.Usedasshielding,watercanprotectpeoplefromcosmicradiation.Waterisalsoamediumofenergystorage;itcanbedissociatedintoitscomponenthydrogenandoxygenusingelectricitygeneratedbysunlightandduringlocalnightoreclipse,thesegasescanbecombined back into water to generate electricity. Finally, liquid hydrogen andoxygenare themostpowerful chemical rocketpropellantknown,whichopens thepossibilityfortheMoontobecomeourfirst“offshore”coalingstationintheseaofcislunarspace.

BecausetheMoonisclose,thetimedelayforaround-tripradiosignalislessthanthree seconds. This gift of proximity makes it possible for machines, under thecontrol of operators on Earth, to begin the initial work of establishing ademonstrationresourceprocessingfacilityontheMoon.TransittimestotheMoonareasshortasthreedays,andlaunchopportunitiesarealwaysavailable.Somepeaksand crater rims near the ice-rich lunar poles experience nearly constant sunlight,permitting the near-constant generation of electrical powerwith solar arrays.Theindividual pieces of equipment necessary to begin the harvesting of lunar ice aresmallandcanbelaunchedonsmallandmedium-liftrockets.Wecanbegintoinstallandoperatea lunarpolar resourceextraction facilitynow,withoutwaiting for theadventofnew,heavyliftlaunchsystems.Ascaled,incrementalapproachtobuildinga facility on the Moon can fit under nearly any budgetary envelope and offers

numerous,intermediatemilestonestodocumentaccomplishmentandtomapsteadyprogress.Finally,theuseofmultiple,smallstepstodeveloptheMoonfacilitatestheparticipationofbothinternationalandcommercialpartnersincreatingapermanentspacetransportationsystem.

MakingtheMoonandcislunarspaceournextstrategicgoalinspacesolvesmanyproblems.Itcreatesanear-term(decadal,notmultidecadal)objectiveagainstwhichprogresscanbedemonstratedandmeasured,invitingmyriadideasandparticipation.Itcanbebuiltinincrementalsteps,tailoredtobeaffordableunderawidevarietyofrestrictivebudgetregimes.Itcreatesalastinginfrastructurethatallowspeopleandmachines access to all of the locations in cislunar space—the locationof scientific,economic,andstrategicassets.Wewillfinallyhavelaidthegroundworknecessarytonavigate past self-imposed roadblocks, thereby opening the solar system toexploration through the creation of a space transportation network that allowsroutinedeparturefrom,andreturnto,lowEarthorbit.

Becausewearedependent on space assets—the technology that controls, assists,andenhancessomuchofourdailylives—thecurrentaimlessdirectionofourcivilspace programnot only endangers the agency’s future but also jeopardizes criticalnationalinterests.Creatingroutineaccesstocislunarspacewillallowustograduatefromthe“flagsandfootprints”modelofhumanspacetraveltothecreation,use,andcontrolofatrue,long-termspacefaringcapability.Wecandothisinamannerthatisscalableandthusaffordable.Itistherightdirectionforourcivilspaceprograminthenewmillennium.

Developing cislunar space and the Moon is a challenging but achievable goal.Although we are uncertain where this journey ultimately will take us, historyrecords that humanity always gains knowledge and prosperswhenwe expand ourhorizons.UsingtheMoon’sresourcestoexplorespaceandtoliveandprospertherewillincreaseourchancesforlong-termsurvivalandimproveourqualityoflife.Thisgreatchallengeholdsthepromiseofbreakthroughtechnologiesandnewdiscoveriesthatwillensurebetterfuturesforusall.

NOTES

1.Luna:Earth’sCompanioninSpace

1SeeB.Brunner,Moon:ABriefHistory(NewHaven:YaleUniversityPress,2010),forareadablecompilation

oftheculturalinfluencesoftheMoononhumanity.

2D.J.Boorstin,TheDiscoverers(NewYork:Vintage,1985).

3E.A.Whitaker,MappingandNamingtheMoon:AHistoryofLunarCartographyandNomenclature

(Cambridge:CambridgeUniversityPress,1999).

4SeeW.G.Hoyt,CoonMountainControversies:MeteorCraterandtheDevelopmentofImpactTheory(Tucson:

UniversityofArizonaPress,1987),foralivelyrecountingofthiscontroversy.

5G.K.Gilbert,“TheOriginofHypotheses,IllustratedbytheDiscussionofaTopographicProblem,”Science

3,no.53(1896):1–15;http://www.sciencemag.org/content/3/53/1.extract.

6W.Ley,Rockets,MissilesandMeninSpace(NewYork:Viking,1966).

7D.E.Wilhelms,ToaRockyMoon:AGeologist’sHistoryofLunarExploration(Tucson:UniversityofArizona

Press,1993).

8Ibid.

9J.L.Powell,NightComestotheCretaceous:DinosaurExtinctionandtheTransformationofModernGeology

(NewYork:W.H.Freeman,1998).

10J.M.Logsdon,AfterApollo?RichardNixonandtheAmericanSpaceProgram(NewYork:Palgrave

Macmillan,2015).

11H.L.Shipman,HumansinSpace:21stCenturyFrontiers(Plenum,NewYork,1989).Thisprescientbook

presentedaclear-eyedanalysisoftheconditionsunderwhichspacesettlementmightbeachieved(page308,

Table9):

12K.Ehricke,“LunarIndustrializationandSettlement:BirthofaPolyglobalCivilization,”LunarBasesand

SpaceActivitiesofthe21stCentury(Houston,TX:LunarandPlanetaryInstitutePress,1985),827–855;

http://tinyurl.com/ob74goo.

13http://www.cislunarnext.org.

2.TheMoonConquered—andAbandoned

1R.B.Baldwin,TheFaceoftheMoon(Chicago:UniversityofChicagoPress,1949).

2A.C.Clarke,TheExplorationofSpace(NewYork:HarperandBros.,1951).

3H.C.Urey,ThePlanets,TheirOriginandDevelopment(NewHaven:YaleUniversityPress,1952).

4W.G.Hoyt,CoonMountainControversies:MeteorCraterandtheDevelopmentofImpactTheory(Tucson:

UniversityofArizonaPress,1987)

5E.M.Shoemaker,LunarPhotogeologicChartLPC58(1960),

http://www.lpi.usra.edu/resources/mapcatalog/LunarPhotogeologicChart.

6W.vonBraunetal.,AcrosstheSpaceFrontier(NewYork:Viking,1952).

7W.Ley,Rockets,MissilesandMeninSpace(NewYork:Viking,1966).

8C.MurrayandC.B.Cox,Apollo:TheRacetotheMoon(NewYork:Simon&Schuster,1989).

9R.Zimmerman,Genesis:TheStoryofApollo8(NewYork:FourWallsEightWindows,1998).

10SpaceTaskGroup,“ThePost-ApolloSpaceProgram:DirectionsfortheFuture”(1969),

http://www.hq.nasa.gov/office/pao/History/taskgrp.html.

11SeeA.Chaikin,AManontheMoon(NewYork:VikingPress,1994),foranexcellentdescriptionofthe

explorationsandadventuresofthelastthreeApolloexplorations.

12J.L.Powell,NightComestotheCretaceous:DinosaurExtinctionandtheTransformationofModernGeology

(NewYork:W.H.Freeman,1998).

13SeeN.L.Johnson,TheSovietReachfortheMoon(NewYork:CosmosBooks,1995),andA.A.Siddiqi

ChallengetoApollo:TheSovietUnionandtheSpaceRace1945–1974(Washington,DC:NASA,2000),fordetails

ontheSovietlunareffort.

14Ibid.

15K.Adelman,ReaganatReykjavik:Forty-EightHoursThatEndedtheColdWar(NewYork:Broadside

Books,2014).

16http://www.spudislunarresources.com/Opinion_Editorial/Apollo_30_op-ed.htm.

17SeeD.Pettit,“TheTyrannyoftheRocketEquation”(2011),

http://www.nasa.gov/mission_pages/station/expeditions/expedition30/tryanny.html.

18B.G.Drake,ed.,HumanExplorationofMarsDesignReferenceMission5.0,NASASP-2009–566(2009),

http://www.nasa.gov/pdf/373665main_NASA-SP-2009–566.pdf.

19http://en.wikipedia.org/wiki/Apollo_program#Program_cost.

3.AfterApollo:AReturntotheMoon?

1SeeM.D.Tribbe,NoRequiemfortheSpaceAge:TheApolloMoonLandingsandAmericanCulture(New

York:OxfordUniversityPress,2014),foradiscussionofthesocialcriticismoftheApolloprogram.

2J.M.Logsdon,“TheSpaceShuttle:APolicyFailure,”Science232(1986):1099–1105;

http://www.sciencemag.org/content/232/4754/1099.

3L.F.Belew,Skylab:OurFirstSpaceStation,NASASP-400(1977),http://history.nasa.gov/SP-

400/contents.htm.

4D.R.Jenkins,SpaceShuttle:TheHistoryoftheNationalSpaceTransportationSystem(Stillwater,MN:

VoyageurPress,2002).

5E.C.EzellandL.N.Ezell,ThePartnership:AHistoryoftheApollo-SoyuzTestProject,NASASP-4209

(1978),http://www.hq.nasa.gov/office/pao/History/SP-4209/toc.htm.

6T.R.Heppenheimer,TheSpaceShuttleDecision,1972–1981(Washington,DC:SmithsonianInstitutionPress,

2002).

7W.vonBraunetal.,AcrosstheSpaceFrontier(NewYork:Viking,1952).

8Ibid.

9H.E.McCurdy,TheSpaceStationDecision:IncrementalPoliticsandTechnologicalChoice(Baltimore:Johns

HopkinsUniversityPress,1990).

10http://www.astronautix.com/craft/otv.htm.

11W.W.Mendell,ed.,LunarBasesandSpaceActivitiesofthe21stCentury(Houston,TX:LunarandPlanetary

InstitutePress,1985).

12P.D.Spudis,“LunarResources:UnlockingtheSpaceFrontier,”AdAstra23,no.2(Summer2011),

http://www.nss.org/adastra/volume23/lunarresources.html.

13H.H.Schmitt,ReturntotheMoon:Exploration,Enterprise,andEnergyintheHumanSettlementofSpace

(NewYork:Praxis-Copernicus,2006).

14SeeJ.R.Arnold,“IceintheLunarPolarRegions,”JournalofGeophysicalResearch84(1979):5659–5668.

15http://history.nasa.gov/rogersrep/genindex.htm

16NationalCommissiononSpace(PaineReport),PioneeringtheSpaceFrontier(NewYork:BantamBooks,

1986).

17S.K.Rideetal.(RideReport),LeadershipandAmerica’sFutureinSpace(Washington,DC:NASA,1987).

18T.Hogan,MarsWars:TheRiseandFalloftheSpaceExplorationInitiative,NASASpecialPublicationSP-

2007–4410(2007),http://history.nasa.gov/sp4410.pdf.

19Ibid.

20NASA(90-DayStudy),Reportofthe90-DayStudyonHumanExplorationoftheMoonandMars

(Washington,DC:NASA,1989),http://history.nasa.gov/90_day_study.pdf

21Hogan,MarsWars.

22SeeD.Day,“AimingforMars,GroundedonEarth,”TheSpaceReview(2004),

http://www.thespacereview.com/article/106/2.

23SynthesisGroup(StaffordReport),AmericaattheThreshold:TheSpaceExplorationInitiative(Washington

DC:USGovernmentPrintingOffice,1991),http://www.lpi.usra.edu/lunar/strategies/Threshold.pdf.

24E.J.Chaisson,TheHubbleWars(NewYork:HarperCollins,1994).

25Hogan,MarsWars.

26D.R.Baucom,“TheRiseandFallofBrilliantPebbles,”JournalofSocialandPoliticalEconomicStudies29,

no.2(2004):143–190.

27H.E.McCurdy,Faster,Better,Cheaper:Low-costInnovationintheU.S.SpaceProgram(Baltimore:Johns

HopkinsUniversityPress,2001).

28B.J.Butler,D.O.Muhleman,andM.A.Slade,“Mercury:FullDiskRadarImagesandtheDetectionand

StabilityofIceattheNorthPole,”JournalofGeophysicalResearch98,E8(1993):15003–15023.

29S.Nozette,C.Lichtenberg,P.D.Spudis,R.Bonner,W.Ort,E.Malaret,M.Robinson,andE.M.Shoemaker,

“TheClementineBistaticRadarExperiment,”Science274(1996):1495–1498.

30D.B.J.Bussey,P.D.Spudis,andM.S.Robinson,“IlluminationConditionsattheLunarSouthPole,”

GeophysicalResearchLetters26,no.9(1999):1187;D.B.J.Bussey,K.E.Fristad,P.M.Schenk,M.S.Robinson,

andP.D.Spudis,“ConstantIlluminationattheLunarNorthPole,”Nature434(2005):842;

http://en.wikipedia.org/wiki/Peak_of_eternal_light.

31McCurdy,Faster,Better,Cheaper,describesClementine’seffectonsubsequentNASAprograms.

4.AnotherRunattheMoon

1AshorthistoryofthisprogramisavailableattheNASADiscoveryProgramwebsite:

http://discovery.nasa.gov/lib/pdf/HistoricalDiscoveryProgramInformation.pdf.

2P.D.Spudis,“IceontheMoon,”TheSpaceReview(2006),http://www.thespacereview.com/article/740/1.

3N.J.S.StacyandD.B.Campbell,“ASearchforIceattheLunarPoles,”LunarandPlanetaryScienceXXVI

(1995):1672;http://www.lpi.usra.edu/meetings/lpsc1995/pdf/1672.pdf

4GeneShoemakerwaskilledinanautomobileaccidentinAustraliain1997.

5W.H.Lambright,WhyMars:NASAandthePoliticsofSpaceExploration(Baltimore:JohnsHopkins

UniversityPress,2014).

6K.Sawyer,TheRockFromMars:ADetectiveStoryonTwoPlanets(NewYork:RandomHouse,2006).

7Ibid.

8http://www.astrobio.net/topic/solarsystem/mars/deciphering-mars-follow-the-water.

9SeeB.Burrough,Dragonfly:NASAandtheCrisisAboardMir(NewYork:HarperCollins,1998).

10D.M.HarlandandJ.E.Catchpole,CreatingtheInternationalSpaceStation(Berlin:Springer-Praxis,2002).

11FirstLunarOutpost(FLO),NASA-JSC(1992);http://www.nss.org/settlement/moon/FLO.html.

12J.K.Strickland(2011);http://www.nss.org/settlement/mars/AccessToMars.pdf.

13Fleshedoutinafullymature,correctedforminR.ZubrinandR.Wagner,TheCaseforMars:ThePlanto

SettletheRedPlanetandWhyWeMust(NewYork:FreePress,1996).

14SeeChapter3,note29.

15A.MatsuokaandC.Russell,eds.,TheKaguyaMissiontotheMoon(Berlin:Springer,2011).

16SeeB.R.Blair,“QuantitativeApproachestoLunarEconomicAnalysis”(2009),forsomeoftheconclusions

ofthiswork:http://tinyurl.com/pr6ktmd.

17ThissadstoryiswelltoldinM.CabbageandW.Harwood,CommCheck:TheFinalFlightofShuttle

Columbia(NewYork:FreePress,2008).

18DetailsofthislongpolicymakingprocessaredescribedinF.SietzenandK.L.Cowing,NewMoonRising:

TheMakingofAmerica’sNewSpaceVisionandtheRemakingofNASA(Burlington,ON:ApogeeBooks,2004).

19Ibid.

20SeethesedocumentsattheKlausHeissfiles,http://www.spudislunarresources.com/klaus.htm.

21GoldTeamstudyproductsareunpublished;summariespresentedinthisbookaretakenfromfilesinmy

collection.

22ColumbiaAccidentInvestigationBoard(CAIB),ReportoftheColumbiaAccidentInvestigationBoard

(Washington,DC:NASA,2003);http://www.nasa.gov/columbia/home/CAIB_Vol1.html.

23“BushMayAnnounceReturntoMoonatKittyHawk,”SpaceDaily,October29,2003;

http://www.spacedaily.com/news/beyondleo-03a.html.

24SietzenandCowing,NewMoonRising.

25G.W.Bush,“ARenewedSpiritofDiscovery”(2004),WhiteHouse;

http://www.spaceref.com/news/viewpr.html?pid=13404.

5.ImplementingtheVision

1G.W.Bush,“ARenewedSpiritofDiscovery”(2004),WhiteHouse;www.spaceref.com/news/viewpr.html?

pid=13404.

2Itracethisevolution,includingexcerptsfromtheinternalHeadquartersRedteam/BlueTeamactivityina

presentation,“TheVisionandtheMission,”athttp://tinyurl.com/aqer2t.

3http://history.nasa.gov/DPT/DPT.htm.

4SomeinvolvedwiththeDPTcontendthatitwasacapability-driven(ratherthanadestinationdriven)

strategicplanningeffort.SeeH.Thronson,“NASA’sDecadalPlanningTeam(DPT)andtheNASAExploration

Team(NEXT)”(2014),http://history.nasa.gov/DPT/thronson.pdf.TheMarsandQuestforLifefixationsofthe

agencywereneverfarbeneaththesurface.SeeespeciallythispresentationattheNationalAcademyof

Engineeringwebsite:http://www.naefrontiers.org/File.aspx?id=22013.Itreflectsagencythinkingonthistopic.

5http://tinyurl.com/nagq2tn

6http://tinyurl.com/aqer2t.

7Commentsatlastpublicmeeting,AldridgeCommission,June2004:http://tinyurl.com/krlzdpz.

8President’sCommissionontheImplementationofSpaceExplorationPolicy(AldridgeReport),Journeyto

Inspire,InnovateandDiscover(Washington,DC:USGovernmentPrintingOffice,2004).

9Objectives/RequirementsDefinitionTeam(ORDT)for2008LunarReconnaissanceOrbiter,

http://tinyurl.com/k6ffpdx.

10Mini-RFimagingradarinstruments:http://tinyurl.com/n8fnlvl.

11IwroteafewarticlesrecountingmyexperiencesduringtheChandrayaan-1missionforAir&Space

magazine:http://tinyurl.com/koqzdkl,http://tinyurl.com/lhul4b6,http://tinyurl.com/lcdge3v.

12http://tinyurl.com/oh8ktrh.

13http://tinyurl.com/nk78bk8.

14http://www.space.com/15406-blue-origin-private-spacecraft-infographic.html.

15http://www.nasa.gov/about/highlights/griffin_bio.html.

16http://tinyurl.com/pnvgjyr.

17http://www.nasa.gov/exploration/news/ESAS_report.html.

18ColumbiaAccidentInvestigationBoard(CAIB),ReportoftheColumbiaAccidentInvestigationBoard

(Washington,DC:NASA,2003);http://www.nasa.gov/columbia/home/CAIB_Vol1.html.

19J.Marburger,KeynoteAddress,44thGoddardMemorialSymposium(2006),

http://www.spaceref.com/news/viewsr.html?pid=19999.

20http://www.spaceref.com/news/viewpr.html?pid=13404.

21C.Bergin,“DiggingDeeperintoNASA’sMoonPlans,”NASASpaceflight,December4,2006,

http://www.nasaspaceflight.com/2006/12/digging-deeper-into-nasas-moon-plans.Seealso

http://www.nasa.gov/pdf/163896main_LAT_GES_1204.pdf.

22D.Beattie,“JustHowFullofOpportunityIstheMoon?”TheSpaceReview(2007),

http://www.thespacereview.com/article/804/1.

23http://lcross.arc.nasa.gov/index.htm.

24D.Shiga,“NASAMayAbandonPlansforMoonBase,”NewScientist(2009),http://tinyurl.com/oz54p2x.

25http://tinyurl.com/koqzdkl.

26P.D.Spudisetal.,“InitialResultsfortheNorthPoleoftheMoonfromMini-SAR,Chandrayaan-1,”

GeophysicalResearchLetters37(2010),http://tinyurl.com/pl5hjh6.

27P.D.Spudis,“ReturntotheMoon:OutpostorSorties?”Air&Space(2009),http://tinyurl.com/mkhtflz.

28http://tinyurl.com/lyg4du.

29N.R.Augustineetal.(AugustineReport),AdvisoryCommitteeontheFutureoftheU.S.SpaceProgram

(Washington,DC:NASA,1990),http://history.nasa.gov/augustine/racfup1.htm.

30ReviewofHumanSpaceflightPlansCommittee(AugustineCommittee),SeekingaHumanSpaceflight

ProgramWorthyofaGreatNation(Washington,DC:NASA,2010),

http://www.nss.org/resources/library/spacepolicy/HSF_Cmte_FinalReport.pdf.

31http://history.nasa.gov/DPT/DPT.htm.

32InMay2013,Boldenwasquotedassaying,“Weneedtotryandgetallofusontothesamesheetofmusic

intermsoftheroadmap.[Ifwe]havesomeoneinthenextadministrationwhocouldtakeusbacktoahuman

lunarmission,it’sallover,wewillgobacktosquareone.”http://www.nasaspaceflight.com/2013/05/return-

moon-send-nasa-square-one-bolden.

33Obamaspacepolicyspeech,NASAKennedySpaceCenter,April15,2010;

http://www.nasa.gov/news/media/trans/obama_ksc_trans.html.

34http://www.airspacemag.com/daily-planet/the-authorized-version-156372809.

35http://www.nasa.gov/exploration/systems/sls.

36http://www.spudislunarresources.com/blog/lets-haul-asteroids.

37http://en.wikipedia.org/wiki/Budget_of_NAS.AProjectedbudgetamountsforNASAwithouttheVSE

andprojectedaugmentedbudgetwithVSE(Figure5.2)arefromapresentationbyAdministratorSeanO’Keefe,

availableathttp://tinyurl.com/ns5t3j3.

6.Why?ThreeReasonstheMoonIsImportant

1Asummaryofthesixthemesdevelopedatthisworkshopcanbeseenonaposter:

http://www.nss.org/settlement/moon/NASAwhymoon.pdf.

2SeeJ.LovellandJ.Kluger,LostMoon:ThePerilousJourneyofApollo13(Boston:HoughtonMifflin,1994).

3SeeNationalResearchCouncil,TheScientificContextforExplorationoftheMoon(Washington,DC:

NationalAcademiesPress,2007),http://www.nap.edu/openbook.php?record_id=11954.

4SeeJ.L.Powell,NightComestotheCretaceous:DinosaurExtinctionandtheTransformationofModern

Geology(NewYork:W.H.Freeman,1998).

5P.D.Spudis,“LunarResources:UnlockingtheSpaceFrontier,”AdAstra23,wno.2(Summer2011),

http://www.nss.org/adastra/volume23/lunarresources.html.

6L.A.TaylorandT.T.Meek,“MicrowaveSinteringofLunarSoil:Properties,TheoryandPractice,”Journal

ofAerospaceEngineering18(2005):188–196;

http://www.isruinfo.com/docs/microwave_sintering_of_lunar_soil.pdf.

7D.B.J.Bussey,P.D.Spudis,andM.S.Robinson,“IlluminationConditionsattheLunarSouthPole,”

GeophysicalResearchLetters26,no.9(1999):1187;D.B.J.Bussey,K.E.Fristad,P.M.Schenk,M.S.Robinson,

andP.D.Spudis,“ConstantIlluminationattheLunarNorthPole,”Nature434(2005):842.

8DiscussedindetailinH.H.Schmitt,ReturntotheMoon:Exploration,Enterprise,andEnergyintheHuman

SettlementofSpace(NewYork:Praxis-Copernicus,2006).

9Forexample,seehttp://www.planetary.org/blogs/bill-nye/20130710-the-goal-is-mars.html.

10http://www.nss.org/settlement/mars/AccessToMars.pdf.

11SeethecurrentNASAMarsDesignReferenceMission5.0,http://www.nasa.gov/pdf/373665main_NASA-

SP-2009–566.pdf.

12SpaceTaskGroup,“ThePost-ApolloSpaceProgram:DirectionsfortheFuture”(1969),WhiteHouse,

http://www.hq.nasa.gov/office/pao/History/taskgrp.html;http://www.spaceref.com/news/viewpr.html?

pid=13404.

13See,forexample,W.W.Mendell,“MeditationsontheNewSpaceVision:TheMoonasaSteppingStoneto

Mars,”ActaAstronautica57(2005):676–683;http://www.ncbi.nlm.nih.gov/pubmed/16010766.

14R.Launius,“ExplodingtheMythofPopularSupportforProjectApollo”(2010),

http://tinyurl.com/k9k9jt4.

7.How?ThingsWeShouldHaveBeenDoing

7.How?ThingsWeShouldHaveBeenDoing

1AgoodintroductiontogeneralastronauticsforthenontechnicalreadercanbefoundinG.Swinerd,How

SpacecraftFly(NewYork:Copernicus-Springer,2008).

2Foragood,nontechnicalexplanation,seeD.Pettit,“TheTyrannyoftheRocketEquation”(2001),

www.nasa.gov/mission_pages/station/expeditions/expedition30/tyranny.html.

3Ibid.

4http://www.fai.org/icare-records/100km-altitude-boundary-for-astronautics.

5SeeB.F.Kutteretal.,“APracticalAffordablePropellantDepotinSpaceBasedonULA’sFlight

Experience,”Space2008,AIAA2008–7644(2008),http://tinyurl.com/l2ndspu.

6http://tinyurl.com/qhw5nsu.

7J.M.Logsdon,“TheSpaceShuttle:APolicyFailure,”Science232(1986):1099–1105;

http://www.sciencemag.org/content/232/4754/1099.

8http://www.nasa.gov/exploration/systems/orion/index.html;

http://www.nasa.gov/exploration/systems/sls/index.html.

9http://www.ulalaunch.com/products_deltaiv.aspx.

10http://www.spacex.com/falcon-heavy.

11P.D.SpudisandA.R.Lavoie,“UsingtheResourcesoftheMoontoCreateaPermanentCislunarSpace

FaringSystem,”Space2011,AIAA,2011–7185(2011);

http://www.spudislunarresources.com/Bibliography/p/102.pdf.

12http://solarsystem.nasa.gov/rps/rtg.cfm.

13SpudisandLavoie,“UsingtheResourcesoftheMoon.”

14http://en.wikipedia.org/wiki/Budget_of_NASA.

15SeeD.A.Day,“WhispersintheEchoChamber,”TheSpaceReview(2004),

http://www.thespacereview.com/article/119/1.

16SpudisandLavoie,“UsingtheResourcesoftheMoon.”

17ReviewofHumanSpaceflightPlansCommittee(AugustineCommittee),SeekingaHumanSpaceflight

ProgramWorthyofaGreatNation(Washington,DC:USGovernmentPrintingOffice,2010),

http://www.nss.org/resources/library/spacepolicy/HSF_Cmte_FinalReport.pdf.

8.IfNotNow,When?IfNotUs,Who?

1SeeJ.M.Logsdon,JohnF.KennedyandtheRacetotheMoon(NewYork:PalgraveMacmillan,2010);on

desalination,seehttp://www.desalination.com/museum/office-saline-water-desal-rd-funding-usa.

2SeeR.Rhodes,TheMakingoftheAtomicBomb(NewYork:Simon&Schuster,1986).

3J.Marburger,KeynoteAddress,44thGoddardMemorialSymposium(2006),

http://www.spaceref.com/news/viewsr.html?pid=19999.

4http://history.nasa.gov/spaceact.html.

5P.D.Spudis,“FadedFlagsontheMoon,”Air&Space(July19,2011),http://tinyurl.com/oro7ome.Bolden’s

quotecomesfromtheDenverPostofFebruary12,2010.

6ScienceinOrbit:TheShuttleandSpacelabExperience1981–1986,NASANP-119,Chapter7;

http://history.nasa.gov/NP-119/ch7.htm.

7http://orbitaldebris.jsc.nasa.gov/index.html.

8R.Ridenoure,“BeyondGEO,Commercially:15YearsandCounting,”TheSpaceReview(2013),

http://www.thespacereview.com/article/2295/1.

9http://www.spudislunarresources.com/Opinion_Editorial/Apollo_30_op-ed.htm.

10http://www.dod.mil/pubs/space20010111.pdf.

11http://freebeacon.com/national-security/china-launches-three-asat-satellites.

12http://www.spudislunarresources.com/blog/china-in-space.

13PresidentJ.F.KennedytoJointSessionofCongress,May25,1961:“Wegointospacebecausewhatever

mankindmustundertake,freemenmustfullyshare.”

http://www.nasa.gov/vision/space/features/jfk_speech_text.html.

14Seetheliteraturecitedathttp://www.hq.nasa.gov/office/hqlibrary/pathfindersopinion.htm.

15http://lunar.xprize.org.

16http://ansari.xprize.org.

17http://www.unoosa.org/oosa/SpaceLaw/outerspt.html.

9.AVisittotheFutureMoon

1http://tinyurl.com/knvua7l.

2http://www.nasa.gov/topics/moonmars/features/moon20090924.html.

3mars.nasa.gov/msl/mission/rover.

4http://www.nasa.gov/mission_pages/ladee/main.

5P.D.SpudisandA.R.Lavoie,“UsingtheResourcesoftheMoontoCreateaPermanentCislunarSpace

FaringSystem,”Space2011,AIAA,2011–7185(2011),

http://www.spudislunarresources.com/Bibliography/p/102.pdf.

6http://www.space.com/18694-moon-dirt-3d-printing-lunar-base.html.

7http://www.nss.org/settlement/ColoniesInSpace/colonies_chap06.html.

8http://tinyurl.com/8zf4m5.

9http://www3.nd.edu/~cneal/Lunar-L/Moon-as-a-tape-recorder.pdf

10P.D.SpudisandG.J.Taylor,“TheRolesofHumansandRobotsasFieldGeologistsontheMoon,”in2nd

ConferenceonLunarBasesandSpaceActivitiesof21stCentury,ed.W.Mendell,NASAConferencePublications

3166(1992),1:307–313.http://tinyurl.com/q44zh36.

11http://www.nss.org/settlement/ssp.

12http://www.spaceagepub.com/pdfs/Ignatiev.pdf.

13D.R.Criswell,“SolarPowerviatheMoon,”TheIndustrialPhysicist,April/May2002,

http://tinyurl.com/pmnelod.

14H.H.Schmitt,ReturntotheMoon:Exploration,Enterprise,andEnergyintheHumanSettlementofSpace

(NewYork:Praxis-Copernicus,2006).

15http://lcross.arc.nasa.gov/observation.htm.

16Idiscussthe“FlexiblePath”ideahere:http://tinyurl.com/ok8wsvv.

10.WhereDoWeGoFromHere?

1H.H.Schmitt,“SpacePolicyandtheConstitution”(2011),Americasuncommonsense.com,

http://tinyurl.com/luohafp.

2“ISRUandtheCriticalPathtoMars”(2013),SpudisLunarResourcesBlog,http://tinyurl.com/pw53hm2.

TALUNARLIBRARY

heliteratureoftheMoonisenormous,andthefollowinglistmakesnoclaimtocompleteness.ThesearebooksorsourcesthatIhavefoundtobeimportantin

onewayoranother.SeveralbooksdealwithspacetopicsotherthantheMoon;theyare includedbecause theyare relevant tounderstanding the issues raisedhere.Allbooks have their own bibliographies thatwill allow you to explore their topics ingreaterdepth.

TwoEssentialBooksBothofthesebookscanbedownloadedatnocostontheInternet:

Heiken,G.H.,D.T.Vaniman,andB.M.French,eds.1991.TheLunarSourcebook:AUser’sGuidetotheMoon.

Cambridge:CambridgeUniversityPress.http://www.lpi.usra.edu/publications/books/lunar_sourcebook.

ThedefinitivereferencebookontheMoon,writtenbymorethanthirtyactiveandformerlunarscientists.

ParticularlythoroughonlunarrocksandsoilsandnicelycomplementsWilhelms’sbook(below).Writtenfor

thelayreader,butdoesnotflinchontechnicalconcepts.

Wilhelms,D.E.1987.TheGeologicHistoryoftheMoon.USGeologicalSurveyProfessionalPaper1348.

Washington,DC:USGovernmentPrintingOffice.http://ser.sese.asu.edu/GHM.

ThehistoricalgeologyoftheMoon,writtenbyoneofthepremierlunargeologistsandhistoriansoflunar

science.Thebookiswellwrittenandillustrated.AcogentsummaryofourunderstandingoftheMoonfrom

thestratigraphicperspective.

HistoryLessonChaikin,A.1994.AManontheMoon.NewYork:VikingPress.

DealswithApollofromtheastronauts’perspective.Verywelldoneandinteresting;coversbothscienceand

operations.BasisfortheHBOTVseriesFromtheEarthtotheMoon.

Collins,M.1974.CarryingTheFire:AnAstronaut’sJourneys.NewYork:Farrar,Straus&Giroux.

Thebestbookbyanyastronaut,evenifhedoesdislikegeology!Fascinating,funny,andprofound.Readthis

booktogetarealfeelforwhatgoingtotheMoonwaslike.

Compton,W.D.1989.WhereNoManHasGoneBefore:AHistoryofApolloLunarExplorationMissions.NASA

SpecialPublication4214.Washington,DC:USGovernmentPrintingOffice.http://www.lpi.usra.edu/lunar/

documents/NTRS/collection3/NASA_SP_4214.pdf.

The“official”NASAhistoryofApollolunarexploration.Takesthestancethatlunarflightwasprimarilya

difficultengineeringtask,madeevenmoredifficultbycontinuouslycomplainingscientists(aviewwithwhich

Icansympathize).ComplementsthescientificviewpointbyWilhelms’sToaRockyMoon.

Harland,D.M.2008.ExploringtheMoon:TheApolloExpeditions.Berlin:Springer-Praxis.

Superb,wellillustrated,andcomprehensivehistoryoftheApollomissions,theirgoals,andtheeventsofthe

program.

Heiken,G.,andE.Jones.2007.OntheMoon:TheApolloJournals.Berlin:Springer-Praxis.

http://www.hq.nasa.gov/office/pao/History/alsj/frame.html.

BookversionofthefamousApolloLunarSurfaceJournal,thecompleteonlinetranscriptsoftheApollo

explorationsoftheMoon.Booksummarizestheprincipalexplorationanddiscoveriesofeachmission.

Hoyt,W.G.1987.CoonMountainControversies:MeteorCraterandtheDevelopmentofImpactTheory.Tucson:

UniversityofArizonaPress.

AnexhaustivehistoryofthestudyofMeteorCrater,Arizona,includingmuchonthedebateaboutthecraters

oftheMoon.Highlyrecommended.

Johnson,N.L.1995.TheSovietReachfortheMoon.NewYork:CosmosBooks.http://www.lpi.usra.edu/

publications/books/sovietReach/index.pdf.

BriefhistoryoftheSovietlunarprogram,withemphasisonthebuildingandfateoftheN-1superbooster.

Murray,C.,andC.B.Cox.1989.Apollo:TheRacetotheMoon.NewYork:Simon&Schuster.

MyfavoritebookaboutApollo.Wonderfullytoldengineeringsideofthestory,includinganail-bitingaccount

ofthenear-disasterwealmosthadduringthefirstlandingontheMoon.Capturestheexcitementoftheearly

dayslikenootherbook.

Sawyer,K.2006.TheRockfromMars:ADetectiveStoryonTwoPlanets.NewYork:RandomHouse.

ThesagaofALH84001,thefamousmeteoritefromMarsinwhichevidencesupposedlywasfoundforancient

fossils.Interestingonthepoliticalfalloutfromthediscovery,whichwasconsiderable.

Siddiqi,A.A.2000.ChallengetoApollo:TheSovietUnionandtheSpaceRace1945–1974.NASASP-2000–4408.

Washington,DC:NASA.http://history.nasa.gov/SP-4408pt1.pdfandhttp://history.nasa.gov/SP-4408pt2.pdf.

MassiveandcomprehensivehistoryoftheSovietspaceprogram.Thedefinitivework.

MassiveandcomprehensivehistoryoftheSovietspaceprogram.Thedefinitivework.

Wilhelms,D.E.1993.ToaRockyMoon:AGeologist’sHistoryofLunarExploration.Tucson:Universityof

ArizonaPress.http://www.lpi.usra.edu/publications/books/rockyMoon.

Theclearest,mostcompleteaccountofthehistoryoflunarscienceinthespaceage.Weakontheearlyphases

(whicharewellcoveredinthebooksbyHoytandbySheehanandDobbins),butunsurpassedforlunarscience

startingwithBaldwinandincludinggeologicalmapping,astronauttraining,andsiteselectionfortheApollo

missions.

Wolfe,T.1979.TheRightStuff.NewYork:Farrar,Straus&Giroux.

Thegreatestbookaboutthespaceprogram,eventhoughspaceisactuallyamarginalpartofWolfe’sstory.The

quintessenceofAmericainspiritandsubstance,allthemorestartlinginitscontrasttothepresentspace

programandNASA.

SpacePolicyandProgramHistoryCatchpole,J.E.2008.TheInternationalSpaceStation:BuildingfortheFuture.Berlin:Springer-Praxis.Harland,

D.M.,andJ.E.Catchpole.2002.CreatingtheInternationalSpaceStation.Berlin:Springer-Praxis.

Comprehensivehistoryofthespacestationprogramandoperationsthroughitsconstructionandinitial

operations.

Heppenheimer,T.R.2002.TheSpaceShuttleDecision1965–1972.Washington,DC:SmithsonianInstitution

Press.

———.TheSpaceShuttleDecision,1972–1981.Washington,DC:SmithsonianInstitutionPress.

The“official”NASAhistoryofthedesignandconstructionofthespaceshuttle,endingwithitsfirstflightin

1981.Somewhoworkedintheprogramhavetoldmethattheearlyhistoryissomewhatdistorted.

Hogan,T.2007.MarsWars:TheRiseandFalloftheSpaceExplorationInitiative.NASASpecialPublicationSP-

2007–4410.Washington,DC:NASA.http://history.nasa.gov/sp4410.pdf

Brief,superficialhistoryofthedeclarationandfateofPresidentGeorgeH.W.Bush’sHuman(Space)

ExplorationInitiative.CompletelymissestheMoon-Marscontroversy,whicharguablyhelpedcausethe

demiseofSEI.

Jenkins,D.R.2002.SpaceShuttle:TheHistoryoftheNationalSpaceTransportationSystem.Stillwater,MN:

VoyageurPress.

Comprehensiveandwell-writtenbookontheorigins,building,andflightsofthespaceshuttle.Nicely

Comprehensiveandwell-writtenbookontheorigins,building,andflightsofthespaceshuttle.Nicely

illustrated.

Kitmacher,G.H.2010.ReferenceGuidetotheInternationalSpaceStation:AssemblyCompleteEdition.NASANP-

2010–09–682-HQ.Washington,DC:NASA.http://www.nasa.gov/pdf/508318main_ISS_ref_guide_nov2010.

pdf.

BeautifullyillustratedbookshowinghowtheISSwasassembledandisoperated.Thedefinitivework;Idid

notfullyunderstandthestationuntilIreadthisbook.

Logsdon,J.M.2010.JohnF.KennedyandtheRacetotheMoon.NewYork:PalgraveMacmillan.

———.2015.AfterApollo?RichardNixonandtheAmericanSpaceProgram.NewYork:PalgraveMacmillan.

Twopiecesbythedeanofspacepolicyhistory.LogsdonwrotethedefinitiveworkontheJFKMoondecision

andaimstodothesameforNixonandthespaceshuttle,withsomewhatlesssuccess.

McCurdy,H.E.1990.TheSpaceStationDecision:IncrementalPoliticsandTechnologicalChoice.Baltimore:Johns

HopkinsUniversityPress.

GoodhistoryofthepolicychoicesmadeduringthedesignofFreedom,althoughendingbeforeitsexistential

crisisandsubsequentrebirthastheInternationalSpaceStationinthe1990s.

McDougall,W.A.1985.TheHeavensandtheEarth:APoliticalHistoryoftheSpaceAge.NewYork:BasicBooks.

Exhaustivestudyofthepoliticsofthespaceprogramandgovernmenttechnologyresearchingeneral.

EmphasisontheearlySputnikdays.

Schmitt,H.H.2006.ReturntotheMoon:Exploration,Enterprise,andEnergyintheHumanSettlementofSpace.

NewYork:Praxis-Copernicus.

Mostlydealswiththeprogrammaticaspectsoflunarreturn,focusingontheminingofhelium-3.JackSchmitt

istheonlyprofessionalscientisttohavewalkedontheMoon.

Shipman,H.L.1989.HumansinSpace:21stCenturyFrontiers.NewYork:Plenum.

Insightful,propheticbookthatcorrectlyidentifiedtheneedtodevelopandusetheresourcesofspacetocreate

newcapabilities.

Sietzen,F.,andK.L.Cowing.2004.NewMoonRising:TheMakingofAmerica’sNewSpaceVisionandthe

RemakingofNASA.Burlington,ON:ApogeeBooks.

ThesoleworkontheoriginsoftheVisionforSpaceExplorationpolicy.Theauthorshadaccesstoseveral

insidesources,makingthisaninvaluableresource,althoughitpossessesthedrawbacksofbeingan“instant

insidesources,makingthisaninvaluableresource,althoughitpossessesthedrawbacksofbeingan“instant

history”effort.

Tribbe,M.D.2014.NoRequiemfortheSpaceAge:TheApolloMoonLandingsandAmericanCulture.NewYork:

OxfordUniversityPress.

Annoyingbookaboutthe“whinersofApollo,”those“experts”whocontinuallycomplainedaboutand

denigratedtheefforttogototheMoonthroughoutthe1960s.Amust-read,buttakeDramaminebefore

plungingin.

Zubrin,R.,andR.Wagner.1996.TheCaseforMars:ThePlantoSettletheRedPlanetandWhyWeMust.New

York:FreePress.

Thedefinitiveexpositionofthe“MarsDirect”architecturebyitsoriginator.

MajorCommitteeReportsonSpacePolicyThesearepresentedinchronologicalorder,withoutcomment.AllmaybeaccessedandreadfreeontheInternet.

Theycontainthegood,thebad,andtheuglyofspacepolicy.

SpaceTaskGroup.1969.ThePost-ApolloSpaceProgram:DirectionsfortheFuture.Washington,DC:NASA.

http://www.hq.nasa.gov/office/pao/History/taskgrp.html.

NationalCommissiononSpace(PaineReport).1986.PioneeringtheSpaceFrontier.NewYork:BantamBooks.

http://history.nasa.gov/painerep/begin.html.

Ride,S.K.,etal.(RideReport).1987.LeadershipandAmerica’sFutureinSpace.Washington,DC:NASA.

http://history.nasa.gov/riderep/main.PDF.

NASA(90-DayStudy).1989.Reportofthe90-DayStudyonHumanExplorationoftheMoonandMars.

Washington,DC:NASA.http://history.nasa.gov/90_day_study.pdf

Augustine,N.R.,etal.(AugustineReport).1990.AdvisoryCommitteeontheFutureoftheU.S.SpaceProgram.

Washington,DC:NASA.http://history.nasa.gov/augustine/racfup1.htm.

SynthesisGroup(StaffordReport).1991.AmericaattheThreshold:TheSpaceExplorationInitiative.Washington,

DC:NASA.http://www.lpi.usra.edu/lunar/strategies/Threshold.pdf

CommissiontoAssessUnitedStatesNationalSecuritySpaceManagementandOrganization(Rumsfeld

Commission).2001.ReportoftheCommissiontoAssessUnitedStatesNationalSecuritySpaceManagementand

Organization.Washington,DC:USDepartmentofDefense.http://www.dod.mil/pubs/space20010111.pdf.

ColumbiaAccidentInvestigationBoard(CAIB).2003.ReportoftheColumbiaAccidentInvestigationBoard.

Washington,DC:NASA.http://www.nasa.gov/columbia/home/CAIB_Vol1.html.

President’sCommissionontheImplementationofSpaceExplorationPolicy(AldridgeReport).2004.Journeyto

Inspire,InnovateandDiscover.Washington,DC:USGovernmentPrintingOffice.http://www.nss.org/

resources/library/spacepolicy/2004-AldridgeCommissionReport.pdf.

NationalResearchCouncil.2007.TheScientificContextforExplorationoftheMoon.Washington,DC:National

AcademiesPress.http://www.nap.edu/openbook.php?record_id=11954.

ReviewofHumanSpaceflightPlansCommittee(AugustineCommittee).2010.SeekingaHumanSpaceflight

ProgramWorthyofaGreatNation.Washington,DC:USGovernmentPrintingOffice.http://www.nss.org/

resources/library/spacepolicy/HSF_Cmte_FinalReport.pdf.

NationalResearchCouncil.2014.PathwaystoExploration:RationalesandApproachesforaU.S.Programof

HumanExploration.Washington,DC:NationalAcademiesPress.http://www.nap.edu/openbook.php?

record_id=18801.

LunarClassicsBaldwin,R.B.1949.TheFaceoftheMoon.Chicago:UniversityofChicagoPress.

ThestudybyBaldwinthatgotitallsoright,soearly.ThisbookinspiredHaroldUrey’sinterestintheMoon

andgreatlyinfluencedmanyearlylunarscientists.

Hartmann,W.K.,R.J.Phillips,andG.J.Taylor,eds.1986.OriginoftheMoon.Houston,TX:Lunarand

PlanetaryInstitutePress.http://www.lpi.usra.edu/publications/books/origin-of-the-moon.

ProceedingsofthegreatKonaMoonoriginconferenceandhence,thedefinitivestatementofthegiantimpact

modelfortheoriginoftheMoon.ReviewpapersbyWood,Drake,andHoodareparticularlyworthy;alsosee

thehistoryofthestudyoflunaroriginbyBrush.

Mendell,W.W.,ed.1985.LunarBasesandSpaceActivitiesofthe21stCentury.Houston,TX:Lunarand

PlanetaryInstitutePress.http://www.lpi.usra.edu/publications/books/lunar_bases.

———.1992.SecondConferenceonLunarBasesandSpaceActivitiesofthe21stCentury.Washington,DC:NASA.

http://www.nss.org/settlement/moon/library/lunar2.htm.

Theproceedingsoftwoconferencesin1984and1988.Greatfun.Acollectionofwildfantasiesaboutthe

adventofanotherApolloprogram,cometosaveusallfromthepurgatoryofspacemediocrity.

Mutch,T.A.1970.TheGeologyoftheMoon:AStratigraphicView.Princeton:PrincetonUniversityPress.

Wonderfullywrittenandillustratedaccountofthestratigraphy(layeredrocks)oftheMoon.Althoughitis

fivedecadesold,manyofthebasicconcepts(e.g.,mappingrelativeages)itdescribesremaincurrent.

Schultz,P.H.1976.MoonMorphology:InterpretationsbasedonLunarOrbiterPhotography.Austin:Universityof

TexasPress.

MassivecompilationofLunarOrbiterimagesofjustabouteveryimaginablelunarfeature,classifiedbytype

oflandform.Imagesarewellreproducedonqualitypaper.

Readable,ReliablePopularAccountsofLunarScienceandExplorationCortwright,E.M.,ed.1975.ApolloExpeditionstotheMoon.NASASpecialPublication350.Washington,DC:US

GovernmentPrintingOffice.http://history.nasa.gov/SP-350/toc.html.

AcollectionofessaysonallaspectsoftheApolloprogram,fromboosterrocketstolunarscience,writtenby

participants.Illustratedwithmanycolorphotographs.

Crotts,A.2014.TheNewMoon:Water,ExplorationandFutureHabitation.NewYork:CambridgeUniversity

Press.

Massivereviewofrecentlunarexplorationresults,withconsiderable(perhapstoomuch)attentionpaidto

LunarTransientPhenomena.

Lewis,J.,M.S.Matthews,andM.L.Guerrieri,eds.1993.ResourcesofNearEarthSpace.Tucson:Universityof

ArizonaPress.http://www.uapress.arizona.edu/onlinebks/ResourcesNearEarthSpace/contents.php.

Compilationofreviewpaperscoveringthematerialresourcesofspace,focusingontheMoonandnear-Earth

objects.Writtenbeforethediscoveryoflunarpolarice.

Light,M.1999.FullMoon.NewYork:Knopf.http://www.michaellight.net/fm-intro.

Magnificentcoffee-tablebookofApollophotographs.

Masursky,H.,G.W.Colton,andF.El-Baz,eds.1978.ApolloovertheMoon:AViewFromOrbit.NASASpecial

Publication362.Washington,DC:USGovernmentPrintingOffice.http://history.nasa.gov/SP-362/contents.

htm.

CollectionofthebestphotographstakenfromlunarorbitduringtheApollomissions,eachonepresentedwith

ageologicallyorientedcaptionbyarelevantexpert.

Powell,J.L.1998.NightComestotheCretaceous:DinosaurExtinctionandtheTransformationofModern

Geology.NewYork:W.H.Freeman.

Accessibleaccountofthedevelopmentandpathoftherevolutioningeologycausedbytherecognitionthata

giantimpact65millionyearsagocausedtheextinctionofmanyspecies,includingmostfamously,the

dinosaurs.

Wingo,D.2004.Moonrush:ImprovingLifeonEarthwiththeMoon’sResources.Burlington,ON:ApogeeBooks.

Discussestheconceptoffindinglargeamountsofplatinum-groupmetalsontheMoontoserveahydrogen-

basedenergyeconomyonEarth.IhavesometechnicalissueswiththisideabutagreethattheMooncanserve

theterrestrialeconomy.

Wood,C.A.2003.TheModernMoon:APersonalView.Cambridge,MA:SkyPublishing.

NicelyillustratedtourofthenearsideoftheMoonfortheamateurastronomer,punctuatedbysomebrief

geologicalnarrativesandanecdotalstoriesofvariouslunarscientists.

LunarAtlasesandMapsBowker,D.E.,andJ.K.Hughes.1971.LunarOrbiterPhotographicAtlasoftheMoon.NASASpecialPublication

206.Washington,DC:USGovernmentPrintingOffice.http://www.lpi.usra.edu/resources/lunar_orbiter.

ThedefinitivecollectionofLunarOrbiterpictures,showingalmosttheentirelunarsurface,bothnearandfar

sides.Itsvalueissomewhathamperedbyrelativelypoorreproductionofsomeofthephotographs.Now

availableinanonlineedition.

Bussey,B.,andP.D.Spudis.2012.TheClementineAtlasoftheMoon.Revisededition.Cambridge:Cambridge

UniversityPress.

ThebestandmostcomprehensiveatlasoftheMoon(ifIdosaysomyself),showingthesurfaceand

nomenclatureoftheentirelunarsurfaceataconsistentscaleanddegreeofdetail.Includesabriefhistoryand

descriptionofthefindingsoftheClementinemission,whichrevolutionizedourunderstandingoftheMoon.

Hare,T.M.,R.K.Hayward,J.S.Blue,andB.A.Archinal.2015.ImageMosaicandTopographicMapofthe

Moon.USGeologicalSurveyScientificInvestigationsMap3316.Washington,DC:USGeologicalSurvey.

http://dx.doi.org/10.3133/sim3316.

Thecurrent“official”versionoftheUSGSmapsbasedonimagesandtopographicdatareturnedbytheLunar

ReconnaissanceOrbitermission.Topographicmap(sheet2)isvirtuallyworthlessbecauseofpoorselectionsfor

colorrendering.

NationalGeographicSociety.1976.TheEarth’sMoon.Secondedition.Washington,DC:NationalGeographic

Society.

ThebestmapoftheMoon,showingbothnearandfarsides(withmajorfeaturenames)onasinglesheetata

scaleof1:10,000,000.MarginsarefilledwithfascinatingfactsanddrawingsabouttheMoonandanindexof

namedformations.

Rükl,A.1990.HamlynAtlasoftheMoon.London:Hamlyn.

ExcellentatlasofthenearsideoftheMoon,particularlyusefulforamateurastronomersandobservers.Each

mapintheatlasgivesabriefentryonthepeopleforwhomcraterswerenamed.

Stooke,P.J.2007.TheInternationalAtlasofLunarExploration.Cambridge:CambridgeUniversityPress.

Compilationofmapsshowingtheresultsofalllunarmissionstodate,atavarietyofscales.Essentialforthe

truelunarfanatic.

Whitaker,E.A.1999.MappingandNamingtheMoon:AHistoryofLunarCartographyandNomenclature.

Cambridge:CambridgeUniversityPress.

ThehistoryofthemappingoftheMoonbyoneofthegreatscholarsofthatfield.Definitiveandauthoritative.

MoonLoreandCulturalHistoryBrunner,B.2010.Moon:ABriefHistory.NewHaven:YaleUniversityPress.

Acollectionofmiscellany,myths,lore,andlegendsdealingwiththeMoon.Entertainingandfastpaced.

Montgomery,S.L.1999.TheMoonandtheWesternImagination.Tucson:UniversityofArizonaPress.

FascinatingstoryoftheroleoftheMooninthehistoryofcultureandscience.Wellwrittenandinteresting.

Sheehan,W.P.,andT.A.Dobbins.2001.EpicMoon:AHistoryofLunarExplorationintheAgeoftheTelescope.

Richmond,VA:Willman-Bell.

ThestoryoftheastronomerswhodevotedthemselvestolearningasmuchabouttheMoonaspossibleinthe

yearsbeforewecouldactuallygothere.

OnlineResourcesTheadventoftheInternethasmadeamultitudeofhistoricalandscientificdocumentsavailableforreference

andenlightenment.HereareafewWebsitesthatcontainusefulinformationthatexpandsuponandaddstothe

ideaspresentedinthisbook.

SpudisLunarResources:http://www.spudislunarresources.com

Mypersonalsite,containingpapers,documents,graphics,andaudiovisualmaterialssupportingtheideas

discussedinthisbook.Aspecialsectionlabeledonthehomepage(“Links”)consistspartlyofunpublished

documentsthatmakeupcriticalpartsofthehistoryoftheVisionforSpaceExploration.Ialsowriteblogposts

thatdiscusscurrentissuesinspacescienceandpolicy.

DevelopCislunarSpaceNext:http://www.cislunarnext.org

AWebsitethatIcreateddevotedtothedevelopmentofcislunarspace,includingtheutilizationoflunar

resourcestocreatenewspacefaringcapabilities.

TheLunarandPlanetaryInstitute:http://www.lpi.usra.edu

Maintainsanunparalleledresourceofhistoricaldocumentsandlunardata.ThesectionontheMooncontains

lunaratlases,imagelibraries,maps,documents,andothermaterialsrelatedtotheexplorationoftheMoon,

pastandfuture.

TheApolloLunarSurfaceJournal:http://www.hq.nasa.gov/alsj

Transcriptsofmissionsoperations,oneofthepremierdocumentstheApollovoyagesoflunarexploration,

images,videos,audios,andhundredsofothergoodies.Tosimplycallitgloriousistodamnitwithfaintpraise

—exploringitmeritsmanyhoursofyourtime.

ApolloImageGallery:http://www.apolloarchive.com/apollo_gallery.html

ThesiteIalwaysgotowhenIneedaspecificdigitalpicturefromoneoftheApollomissions.Organizedby

mission,thiscollectionisawonderfulasset.

HistoryofSpacePolicy:http://www.hq.nasa.gov/office/pao/History/spdocs.html

Acollectionofvariouspolicypapers,documents,andreportsthatdetailnationalpolicyoncivilspaceover

time.

LunarReconnaissanceOrbiterCameraQuickmap:http://target.lroc.asu.edu/q3

Web-basedGISsystemthatallowsyoutoviewanyspotontheMoonfromagreatdistanceorclose-up.

Overlaysincludenomenclature,otherdatasets(e.g.,Mini-RFradar,topography),andevencurrentlighting

conditions.AdreamsiteforfansoftheMoon.

FilmandVideoDocumentariesandHistoryDocumentaryfilmscanbeanenjoyablewaytoabsorbandunderstandtechnicalinformationaboutthehistoryof

thespaceprogramandlunarexploration.ThefollowingaresomeoftheonesthatIenjoyed.

ForAllMankind.1989.NationalGeographicVideo,79min.

AdocumentarymadeupoffootagefromalloftheApollomissions,artisticallycombinedintoasingle

continuousnarrativeonhowweexploredtheMoon.

IntheShadowoftheMoon.2007.DiscoveryFilms,100min.

TheoversizedroleoftheApollomissionsonthelivesofthosewhoflewthem.Includesmanyinterviewswith

theastronauts.

MoonMachines.2008.DiscoveryChannel,6episodes,60min.each.

SeriesonthemajorpiecesoftheApollosystem—thelaunchvehicle,thespacecraft,andguidancecomputers.

Thehistoryofanengineeringmarvel.

TotheMoon.1999.Nova,WGBH-Boston,120min.

ThestoryoftheMoonraceofthe1960s.Includesinterviewswithalltheprincipals:engineers,managers,

astronauts,andscientists.

WhenWeLeftEarth:TheNASAMissions.2008.DiscoveryChannel,6episodes,60min.each.

SeriesthatcompilesthousandsofhoursofNASAfilmandvideointoanarrativeofhumankind’sfirststepsinto

thecosmos.

LunarFeatureFilmClassicsLetusfinallypayhomagetothepowerofimagination.Thesemoviesareatthetopofmylist.

DestinationMoon.1950.SinisterCinemaVideo,91min.

BasedonaRobertHeinleinshortstory,thisfilm,producedbyGeorgePal,triedto“educate”thepublicback

BasedonaRobertHeinleinshortstory,thisfilm,producedbyGeorgePal,triedto“educate”thepublicback

atthedawnofthespaceageaboutthingstocome.Amilestonescience-fictionfilmthatincludeswonderful

spaceartbythegreatChesleyBonestell.ListentothedescriptionoftheMoonbythespaceshipcrewand

compareittotheuncannilysimilarwordsofNeilArmstrongandBuzzAldrin,onlytwentyyears(butan

emotionallifetime)later.

2001:ASpaceOdyssey.1968.MGMVideo,139min.

Theultimatespacemovie—philosophical,intellectual,emotional,profound.Thefilm,amasterpieceby

StanleyKubrick,takesgreatprideingettingeverytechnicaldetailright,evendowntothesubtletiesof

weightlessnessandartificialgravity.SohowcometheMoonchangesitsphaseforward,backward,andin

eight-dayleapsduringthevoyagebetweenthespacestationandClaviusBase(alousyplaceforalunar

outpost,bytheway)?DuringthesceneatTycho,havingtheEarthappearsolowonthehorizonisalsowrong

(Tychoisat43°Slatitude,sotheEarthwouldappearhalfwaybetweenthehorizonanddirectlyoverhead).

Still,there’snothinglikeitforthe“feel”ofspaceflight.

Apollo13.1995.UniversalPictures,130min.

Thisfilm,directedbyRonHoward,capturesthespiritandsubstanceofApollospaceflight.Thespacescenes

arerealistic(manywerefilmedinreal“microgravity”oftheNASAKC-135aircraft)andgripping.Asusual

withfilmsabouttheMoon(exceptforDestinationMoon),manylibertiesaretakenwithlunargeography;for

example,whileflyingoverTsiolkovsky,onthefarside,crewsaysthatthey“canlookuptowardsMare

Imbrium,”whichisontheopposite,nearsidehemisphere.

FromtheEarthtotheMoon.1998.HBOFilms,12episodes,60min.each

ExcellentTVminiseriestellingthesagaoftheApolloprogram,fromitsbirthtoitsend.Afewclunker

episodes(forexample,theApollo13episodefocusesonthemediaandisprettyworthless—watchthefilm

Apollo13instead).

ILLUSTRATIONCREDITSUnlesslistedbelow,tablesandfigureswerecreatedbytheauthor.

Figure1.1LROCameraTeam,ArizonaStateUniversityFigure2.1LROCameraTeam,ArizonaState

University(ImageLROCNACM1123519889)Figure2.2NASA(ImageAS16–109–17804)

Figure3.1LROCameraTeam,ArizonaStateUniversity/NASAFigure5.1LROMini-RFTeam,Johns

HopkinsUniversityAppliedPhysicsLaboratory/NASAFigure6.1JackFrassanitoandAssociates

Figure6.2LROCameraTeam,ArizonaStateUniversity(ImagesLROCNACM1101573334and

LROCNACM1096850878)Figure7.1MarkMaxwell,courtesySkycorp,Inc.

Figure7.2MarkMaxwell,courtesySkycorp,Inc.

Figure7.3MarkMaxwell,courtesySkycorp,Inc.

Figure9.1LunarandPlanetaryInstituteFigure9.2MarkMaxwell,courtesySkycorp,Inc.

Figure9.3JackFrassanitoandAssociates

INDEX

3-Dprinting,6.1,9.1

90-DayStudy,3.1,4.1,7.1

absorptionband

AerospaceCorporation

agglutinates

aggregate(constructionmaterial),6.1,9.1

Aldridge,Edward(Pete),4.1,5.1

AldridgeCommission,4.1,5.1,5.2,5.3,8.1

Aldrin,EdwinEugene“Buzz,”2.1,5.1

ALH84001(meteorite),4.1,4.2

Altairspacecraft,5.1,5.2,7.1,9.1

Alvarez,Luis

Alvarez,Walter

America’sSpacePrize

ammonia,6.1,9.1

anorthosite,2.1,3.1

Anaxagoras

AnsariX-Prize

Antarctica

antisatellitewarfare(ASAT),8.1,8.2

ApolloApplicationsProgram

Apolloprogram,1.1,2.1,2.2,2.3,2.4,2.5,3.1,3.2,3.3,3.4,5.1,5.2,6.1,7.1,8.1,8.2,8.3,8.4,9.1,10.1;Apollo

programcost,2.6;Apollo1fire,2.7,10.2;Apollo8,2.8,3.5;Apollo11mission,2.9,2.10,3.6,8.5;Apollo12

mission,2.11;Apollo13mission,2.12,2.13,6.2;Apollo14mission,2.14;Apollo15mission,2.15;Apollo16

mission,2.16;Apollo17mission,2.17,10.3;extended(“J-missions”),2.18;modedecision,2.19;public

supportfor,2.20,3.7,8.6;samples,1.2,1.3,2.21,2.22,2.23,3.8,3.9,3.10,3.11,4.1,6.3,9.2;uniquenessof,

2.24

Apollo-SoyuzTestProject(ASTP)

AppliedPhysicsLaboratory(APL),3.1,4.1,5.1,5.2,5.3

architectures,2.1,2.2,3.1,3.2,4.1,4.2,5.1,5.2,5.3,5.4,5.5,6.1,6.2,7.1,7.2,7.3,7.4,7.5,9.1,10.1,10.2

Areciboradiotelescope,4.1,4.2

AristarchusofSamos

Aristarchus(crater)

Aristotle

AsteroidReturnMission(ARM)

atomicbomb,8.1,8.2

Augustine,Norman

AugustineCommittee,4.1,5.1,7.1,9.1

Baldwin,Ralph,2.1

basalt,1.1,2.1,6.1

basins,1.1,1.2,2.1,2.2,2.3,3.1,3.2,4.1;filling,1.3;impactmelt,1.4

bedrock,2.1,9.1

bentbiconic

Bhandari,Narendra

BigelowAerospace

Bolden,Charles,5.1,8.1

bombardment,1.1,2.1,2.2,6.1,6.2;early,1.2,2.3,6.3,9.1;periodic,6.4;

Bonestell,Chesley

breccia,2.1,2.2,2.3;fragmental,2.4

Brahe,Tycho

Brand,Vance

bricks

BrilliantPebblesprogram,3.1,3.2

Buran(Sovietshuttle)

Bush,PresidentGeorgeH.W.(“41”),3.1,3.2,4.1,7.1

Bush,PresidentGeorgeW.(“43”),4.1,5.1,5.2,5.3

carbondioxide,4.1,6.1

carbonmonoxide,6.1,9.1

carbothermalreduction

ceramics,6.1,9.1

Cernan,Eugene

Challengeraccident,3.1,4.1,4.2,5.1,7.1,8.1,10.1

Chandrayaan-1mission,3.1,4.1,5.1,5.2,5.3,9.1

Chang’E-2mission

China,1.1,7.1,8.1,8.2;andantisatellitewarfare,8.3;andtheMoon,1.2,8.4,8.5,8.6;cislunarcapabilities,7.2,8.7,

8.8;spaceprogram,1.3,7.3,8.9

chondrites

circularpolarizationratio(CPR),3.1,4.1

cislunarspace,1.1,3.1,3.2,3.3,5.1,5.2,5.3,6.1,7.1,7.2,7.3,7.4,7.5,7.6,7.7,8.1,8.2,8.3,8.4,9.1,9.2,10.1;

defined,1.2;transferstage(CTS),7.8;valueof,1.3,6.2,7.9,7.10,8.5,8.6,9.3

Clarke,ArthurC.

clay,2.1,6.1,6.2

Clementinemission,1.1,3.1,4.1,4.2,5.1,5.2,5.3,5.4

Clinton,PresidentWilliam,3.1,4.1,4.2,4.3

coldtraps,1.1,1.2,3.1,5.1,6.1,9.1

ColdWar,2.1,3.1,8.1,8.2,8.3,8.4,8.5,8.6

Collier’s,2.1,3.1

ColoradoSchoolofMines

Columbiaaccident,3.1,4.1,4.2,7.1

ColumbiaAccidentInvestigationBoard(CAIB),4.1,4.2,5.1

comets,1.1,1.2,1.3,3.1,6.1,9.1,9.2

Command-ServiceModule(CSM),2.1,5.1,6.1

CommercialCargoandCrewprogram

Conrad,Pete

Constellation,Project,5.1,5.2,5.3,5.4,5.5,7.1,7.2,7.3,7.4,9.1

CoonButte(seeMeteorCrater)

CopernicusCrater

Copernicus,Nicholas

core,lunar,1.1,6.1

cosmicrays,2.1,6.1,6.2

craters,1.1,1.2,1.3,1.4,2.1,2.2,2.3,2.4,3.1,3.2,3.3,4.1,4.2,5.1,5.2,5.3,6.1,6.2,6.3,9.1,9.2,10.1

Cretaceous-Tertiary(KT)boundary,1.1,2.1

CrewExplorationVehicle(CEV),4.1,5.1,5.2,5.3,5.4,7.1

Crippen,Bob

cryogenic,6.1,6.2,7.1,7.2,7.3,9.1

DefenseAdvancedProjectsAgency(DARPA)

delta-v,6.1,6.2,7.1,10.1

DescartesMountains

DesignReferenceMission(Mars)

differentiation,6.1,6.2,9.1

Discoveryprogram,3.1,4.1

Disney,Walt,2.1

Disneyland(TVseries)

deuterium

Duke,Charlie

Duke,Michael,3.1,4.1

dust,1.1,2.1,2.2,3.1,6.1,6.2,6.3,7.1,7.2,9.1,9.2

Eagle(Apollo11LunarModule)

eclipse,7.1,10.1

Ehricke,Krafft

elements,volatile,1.1,1.2,2.1,6.1,6.2,7.1,7.2,9.1,9.2,9.3

energy,1.1,1.2,1.3,3.1,3.2,3.3,4.1,5.1,5.2,5.3,6.1,6.2,6.3,6.4,7.1,8.1,9.1,9.2,10.1;powerbeaming,3.4,9.3;

production,1.4,3.5,5.4,5.5,5.6,6.5,6.6,6.7,7.2,9.4,10.2;solaratpoles,1.5,5.7,5.8,6.8,7.3,7.4,9.5,9.6,

10.3

entry-descent-landing(EDL)problem,4.1,6.1

environment,lunar,1.1,1.2,2.1,3.1,3.2,4.1,5.1,6.1,6.2,6.3,7.1,7.2,7.3,9.1,9.2,9.3;polar12,3.3,4.2,5.2,6.4,

7.4,7.5

erosion

eruptions,solar

eruptions,volcanic,1.1,1.2,2.1,2.2,9.1

Europe,lunarmissionsof,3.1,3.2,4.1,4.2

exploration,1.1,1.2,1.3,2.1,2.2,2.3,3.1,3.2,4.1,4.2,4.3,5.1,5.2,5.3,7.1,7.2,7.3,8.1,8.2,8.3,9.1,9.2,9.3,10.1,

10.2;duringApollo15,2.4,2.5,2.6,8.4;field,2.7,2.8,9.4;human,2.9,3.3,3.4,4.4,4.5,5.4,5.5,7.4,8.5,

8.6,9.5,9.6;reconnaissance,9.7;robotic,5.6,7.5,9.8,9.9

ExplorationSystemsArchitectureStudy(ESAS),5.1,5.2

Explorer1mission

extinctions,1.1,2.1,9.1

extravehicularactivity(EVA),1.1,7.1,7.2

farsideofMoon,1.1,3.1,3.2,5.1,6.1,9.1;astronomyfrom,6.2

Faster-Better-Cheaper(FBC)paradigm,3.1,3.2,4.1,4.2,4.3

FederalAviationAdministration(FAA)

federallyfundedresearchanddevelopmentcenter(FFRDC)

feedstock,6.1,6.2,7.1,7.2,9.1

Fiorina,Carly

FlexiblePath,5.1,9.1

Foote,Albert

FraMauro

fuel,rocket(seepropellant)

fusionpower,3.1,6.1,9.1

Gagarin,Yuri,8.1

Galileo

Garver,Lori

Geminiprogram,2.1,3.1

Genesisrock

geologicalactivity,1.1,1.2,2.1,6.1,9.1

geology,2.1,2.2,4.1,9.1

geosynchronousorbit(seeorbit)

Gilbert,GroveKarl,1.1,2.1

glass,2.1,6.1,9.1,9.2;black-and-orange,2.2;green,2.3;pyroclastic,2.4,9.3

globalpositioningsystem(GPS),7.1,8.1,8.2

Goddard,Robert

GoddardSpaceSymposium

Goldin,Daniel,3.1,3.2,3.3,4.1,4.2,4.3,4.4,5.1

goldrushof1849(California)

Goldstoneradiotelescope,3.1,4.1

GoldTeam,4.1,5.1

GoogleLunarX-Prize

Gore,VicePresidentAlbert

Griffin,Michael,5.1,5.2

HadleyRille

helium-3(3He),3.1,6.1,9.1

heavyliftvehicle,3.1,6.1,7.1,7.2,7.3,7.4,7.5,7.6

Heiss,Klaus

highlands,1.1,2.1,2.2,2.3(seealsoterrae)

HLV(seeheavyliftvehicle)

Holdren,John,5.1,5.2

Horowitz,Scott(“Doc”)

Houbolt,John

HubbleSpaceTelescope,3.1,4.1,4.2,8.1,8.2,10.1

hydrogen,1.1,2.1,3.1,3.2,4.1,4.2,5.1,5.2,6.1,6.2,6.3,7.1,7.2,7.3,7.4,8.1,9.1,9.2,10.1

hydrogensulfide

Imbriumbasin,1.1,2.1

impacts(natural),1.1,1.2,1.3,1.4,2.1,2.2,2.3,3.1,3.2,4.1,4.2,5.1,5.2,6.1,6.2,6.3,9.1,9.2

India,3.1,4.1,4.2,5.1,5.2;Chandrayaan-1mission,3.2,4.3,5.3,5.4,5.5,9.1

insituresourceutilization(ISRU),1.1,3.1,4.1,5.1,6.1,6.2

IntercontinentalBallisticMissile(ICBM)

InternationalSpaceStation(ISS),1.1,1.2,4.1,4.2,5.1,6.1,8.1,8.2,8.3,10.1

InterstateHighwaySystem

Irwin,James

Jackson,Michael,5.1

JamesWebbSpaceTelescope(JWST)mission

JointStrikeFighterprogram

Kaguya(seeSELENEmission)

Karmanline

Keaton,Paul

Kennedy,PresidentJohnF.,1.1,1.2,2.1,2.2,2.3,5.1,8.1,8.2

Kepler,Johannes,1.1,2.1

Kerwin,Joe

KittyHawk,NorthCarolina

Kubasov,Valeri

Kuiper,Gerard

landing:lunar,1.1,1.2,1.3,2.1,2.2,2.3,3.1,5.1,5.2,5.3,6.1,6.2,7.1,7.2,7.3,8.1,8.2,9.1,9.2,9.3;martian,4.1,

5.4,6.3,9.4;sites,2.4,2.5,5.5,5.6,7.4,9.5

launch:costs,6.1,7.1;windows,1.1,6.2,6.3,6.4

lava,1.1,1.2,1.3,2.1,2.2,2.3,2.4,6.1

L-points(Libration,Lagrangian),4.1,6.1,9.1

Lavoie,Anthony(Tony),5.1,7.1,7.2

LawrenceLivermoreNationalLaboratory,3.1,3.2,4.1

Leonov,Alexsei,2.1,3.1

Leshin,Laurie

Lincoln,PresidentAbraham

life,extraterrestrial,4.1,4.2,5.1,6.1,6.2,6.3

LucianofSamosota

Luna2mission

lunarbase(outpost),1.1,2.1,3.1,4.1,4.2,6.1

LunarArchitectureTeam(LAT),5.1,7.1

LunarAtmosphereandDustEnvironmentExplorer(LADEE)

LunarBaseSymposium

lunarexploration,1.1,2.1,3.1,4.1,5.1,7.1

LunarModule(LM),2.1,3.1,3.2,5.1,6.1,6.2,9.1

lunarorbitrendezvous

LunarOrbiterprogram,1.1,3.1

LunarPolarOrbiter(LPO)mission,3.1,3.2,4.1

LunarCraterObservationandSensingSatellite(LCROSS),1.1,3.1,4.1,5.1,9.1,9.2

LunarProspector(LP)mission,1.1,3.1,4.1,4.2,4.3,5.1,5.2

LunarReconnaissanceOrbiter(LRO)mission,1.1,2.1,3.1,5.1,5.2,5.3,5.4,6.1,9.1

lunarreturn,1.1,3.1,3.2,4.1,4.2,4.3,4.4,5.1,5.2,5.3,5.4,5.5,5.6,6.1,7.1,7.2,7.3,7.4,8.1,8.2,9.1,9.2,9.3;

analogytoAmericanWest,8.3;firststeps7.5;reasonsfor,6.2,6.3

LunarRovingVehicle(LRV)(seerover)

Lyles,Les

magneticfields,1.1,2.1,3.1,6.1

magnetosphere

ManhattanProject

maps,2.1,3.1,3.2,4.1,4.2,5.1,5.2,9.1;chemical,3.3,5.3;geological,2.2;gravity,3.4;mineral,3.5,5.4;radar,3.6,

4.3,5.5,5.6,5.7;topographic,3.7

Marburger,John,4.1,5.1,8.1

MareNectaris

maria,1.1,1.2,2.1,6.1,6.2;agesof,1.3,1.4,6.3;scarcityonfarside,1.5

Mars,1.1,2.1,2.2,2.3,2.4,3.1,3.2,3.3,3.4,4.1,4.2,4.3,5.1,5.2,5.3,5.4,5.5,5.6,5.7,5.8,6.1,6.2,6.3,7.1,7.2,9.1,

9.2,10.1;DesignReferenceMission(DRM),2.5;Direct,4.4,4.5;distancefromearth,6.4;humanmissions

to,2.6,2.7,2.8,3.5,3.6,4.6,4.7,4.8,5.9,5.10,5.11,5.12,5.13,5.14,5.15,5.16,6.5,6.6;lifeon,4.9,4.10,

5.17,6.7;meteoriteson,4.11;requirementsforcolonization,4.12,4.13,5.18,5.19,5.20,6.8,6.9,6.10,7.3,

7.4,10.2;roboticmissionsto,3.7,3.8,4.14,4.15,5.21,6.11,9.3,9.4,10.3;Shergottite-Nahklite-Chassignite

(SNC),4.16

MarsClimateOrbitermission

MarsExplorationRover(MER)mission

MarsObservermission,3.1,3.2,4.1

MarsPathfindermission,4.1,4.2

MarsPolarLandermission

MarsScienceLaboratory(MSL)

massdriver

massifs

McAuliffe,Christa

Mendell,Wendell

Mercury,2.1,3.1;polesof,3.2

Mercuryprogram

MeteorCrater,Arizona,1.1,2.1

methane,4.1,6.1,9.1

microgravity,6.1,7.1,8.1

middleEarthorbit(MEO),7.1,8.1

minerals,1.1,2.1,3.1,3.2,3.3,6.1,6.2,9.1,9.2;ilmenite,9.3;maskelynite,2.2;olivine,3.4;plagioclase,2.3,3.5;

pyroxene,3.6;quartz,2.4

Mini-RF(Mini-SAR)experiment,5.1,5.2,5.3,9.1

Mir(Sovietspacestation)

month

Moon:accessibilityof,1.1,6.1,6.2;asaspacestation,1.2;atmosphereof,1.3,6.3,9.1;compositionof,3.1,3.2,4.1,

6.4,6.5,9.2,9.3,9.4;core,1.4,6.6;crustof,1.5,1.6,1.7,2.1,2.2,3.3,4.2,6.7,6.8;distancefromEarth,1.8,

6.9;environment,1.9,1.10,2.3,3.4,3.5,4.3,5.1,6.10,6.11,6.12,7.1,7.2,9.5,9.6,9.7;exitstrategy,6.13,

7.3;GPSsystemand,7.4,7.5,8.1,8.2;librationpointsof,5.2,7.6,9.8;magmaoceanon,1.11,3.6;mantle

of,1.12,2.4,3.7,6.14;mythologyof,1.13;permanentshadow,1.14,3.8,3.9,4.4,6.15,7.7;permanent

sunlight,1.15,1.16,1.17,3.10,3.11,4.5,4.6,5.3,6.16,6.17,7.8,7.9,8.3,8.4,9.9,10.1;phasesof,1.18;poles

of,1.19,1.20,1.21,1.22,3.12,3.13,3.14,4.7,4.8,4.9,4.10,5.4,5.5,5.6,5.7,5.8,6.18,6.19,6.20,7.10,7.11,

7.12,7.13,8.5,8.6,9.10,9.11,10.2;proximity,1.23,1.24,1.25,1.26,4.11,5.9,6.21,6.22,6.23,7.14,7.15,

10.3;regolith2.5,3.15,4.12,6.24,6.25,6.26,6.27,6.28,7.16,7.17,9.12,9.13;returnto,1.27,1.28,1.29,2.6,

3.16,3.17,3.18,4.13,4.14,4.15,4.16,5.10,5.11,5.12,5.13,5.14,5.15,5.16,6.29,7.18,7.19,8.7,8.8,9.14,

9.15,10.4,10.5;roadson,6.30,7.20,7.21,9.16;seismicity,6.31;stratigraphyof,2.7;witnessplate

(recorder),1.30,1.31,1.32,2.8,2.9,6.32,6.33,7.22,9.17

MoonExpressInc.

MoonImpactProbe(MIP)

MoonMineralogyMapper(M3)experiment,5.1,9.1

Moran,Jim

NansenCrater

NationalAeronauticsandSpaceAdministration(NASA):abolitionof,10.1;AmesResearchCenter,5.1;Apollo

program,2.1,2.2,2.3,3.1;budgetof,3.2,4.1,4.2,4.3,5.2,5.3,5.4,5.5,6.1,7.1,10.2,10.3;Decadal

PlanningTeam,5.6,5.7;ExplorationStrategyWorkshop,5.8,6.2;Explorationteam(NEXT),5.9;

GoddardSpaceFlightCenter,3.3,5.10;JetPropulsionLaboratory,3.4,4.4,5.11,5.12;JohnsonSpace

Center,2.4,3.5,4.5;KennedySpaceCenter,5.13;MarshallSpaceFlightCenter,5.14,7.2;PublicAffairs,

8.1

NationalAirandSpaceMuseum,3.1,3.2,8.1

NationalCommissiononSpace,3.1,4.1

NationalSecurityCouncil(NSC)

NavalResearchLaboratory,3.1,3.2,4.1

near-Earthasteroids(humanmissionsto),4.1,5.1,6.1,6.2

Near-EarthAsteroidRendezvous(NEAR)mission

nearsideofMoon,1.1,1.2,2.1,3.1,4.1,6.1,6.2,6.3,9.1

NEO(seenear-Earthasteroids)

NewSpace,6.1,8.1,8.2

Newton,SirIsaac

Nixon,PresidentRichard

NorthAmericanAerospaceDefenseCommand(NORAD)

Nozette,Stewart,3.1,3.2

nuclearreactors,3.1,4.1,4.2,6.1,7.1,9.1

Obama,PresidentBarack,5.1,5.2

Oberth,Hermann

obliquity,1.1,1.2,3.1

Ockels,Wubbo

OfficeofManagementandBudget(OMB)

OfficeofScienceandTechnologyPolicy(OSTP)

O’Keefe,Sean,4.1,5.1,nts.1

orbits,1.1,1.2,1.3,1.4,1.5,2.1,2.2,3.1,3.2,3.3,3.4,3.5,4.1,5.1,5.2,6.1,6.2,6.3,6.4,6.5,7.1,7.2,7.3,7.4,7.5,8.1,

8.2,9.1,9.2,9.3,10.1;distantretrograde(ARM)5.3;elliptical,1.6,6.6;geosynchronous1.7,3.6,6.7,7.6,

8.3,8.4;lowEarth(LEO)3.7,6.8,6.9,6.10,7.7,7.8,8.5,10.2;lowlunar(LLO)6.11,6.12,7.9,9.4;middle-

Earthorbit(MEO),7.10,8.6;phasing,3.8;polar,3.9,3.10,3.11,3.12,4.2,7.11;propellantdepots,7.12,

7.13,7.14,7.15,7.16,9.5;servicing,8.7

OrbitalTransferVehicle(OTV),1.1,3.1,3.2

oredeposit

Orionspacecraft,5.1,5.2,5.3,5.4,7.1,7.2,9.1

OuterSpaceTreaty(UnitedNations)

oxygenproduction,1.1,3.1,4.1,6.1,7.1,7.2,8.1,9.1,9.2,10.1

Paine,Thomas,3.1,4.1

paleoregolith

PanamaCanal

Pantheon(Rome)

peak,3.1,3.2,3.3,6.1,10.1;central,3.4,6.2;ofeternallight,3.5,3.6,3.7,10.2

plagioclase,2.1,3.1

plains,1.1,6.1,9.1

PlanetarySociety4.1,5.1,5.2

poles(seeMoon,polesof)

powerstations,3.1,4.1,4.2,5.1,6.1,7.1,7.2,7.3,7.4,8.1,9.1,9.2,9.3,9.4,10.1

propellant,1.1,1.2,2.1,4.1,4.2,5.1,6.1,6.2,6.3,6.4,6.5,7.1,7.2,7.3,7.4,8.1,8.2,8.3,9.1,10.1;boil-off,6.6,7.5,

7.6,7.7,9.2;depots,2.2,3.1,7.8,7.9,7.10,8.4,9.3,9.4

prospecting,6.1,7.1,8.1,9.1

publicopinion,2.1,3.1,3.2,5.1,5.2,5.3,6.1,6.2,8.1,8.2

pyroxene

quartz

QuestforLife,4.1,5.1,6.1

radioastronomy,4.1,6.1

radioactivity,3.1,4.1,6.1

radioisotopethermalgenerator(RTG)

Rangerprogram

Reagan,PresidentRonald,2.1,3.1,4.1,8.1

Readdy,William,4.1,5.1,5.2

regenerativefuelcell(RFC)

rendezvous,1.1,2.1,2.2,3.1,5.1,6.1,7.1,8.1,9.1

Ride,Sally

Ridereport,3.1,4.1

roboticteleoperations(seeteleoperation)

rocks,1.1,1.2,2.1,2.2,2.3,3.1,4.1,4.2,5.1,6.1,6.2,9.1,9.2

rocket,1.1,1.2,2.1,2.2,2.3,2.4,3.1,3.2,3.3,3.4,4.1,5.1,5.2,5.3,6.1,7.1,7.2,7.3,8.1,9.1,9.2,10.1;Ares,5.4,5.5,

7.4;Atlaslauncher,7.5;combustion,7.6;equation,2.5,2.6,3.5,7.7,7.8;Falcon9launcher,7.9;Falcon

Heavylauncher,7.10;N-1,2.7;Nova,2.8;nuclear,4.2;SaturnV,2.9,2.10,4.3;Shuttleside-mount,5.6;

solidrocketmotors,3.6,5.7,5.8,5.9,7.11;SpaceLaunchSystem(SLS),6.2,7.12;TitanII,3.7

Rogers,William

rovers,2.1,4.1,4.2,5.1,5.2,6.1,7.1,9.1,9.2,9.3,9.4

RümkerKcrater

Rustan,Pedro

Sagan,Carl,4.1,9.1

samples,1.1,1.2,2.1,2.2,3.1,3.2,3.3,3.4,4.1,6.1,9.1

Schmitt,HarrisonH.(Jack),2.1,10.1

Scolese,Chris

Scott,David

seismicactivity

SELENEmission

ShackletonCrater,1.1,4.1

SHAR(Indialaunchsite)

Shepard,Alan

shockmelting

Shoemaker,Eugene,2.1,3.1,3.2,3.3,4.1

sinuousrilles

Skylab(spacestation),3.1,3.2

Slayton,Deke

SMART-1mission,3.1,4.1

soil,1.1,1.2,2.1,2.2,3.1,4.1,6.1,6.2,7.1,9.1,9.2,9.3,9.4;asshielding,6.3;composition,3.2,9.5;melting,6.4,9.6

Sojournerrover

solar:eclipse,1.1;electricpropulsion,4.1,5.1,6.1;flares,6.2;nitrogenisotopes,6.3;power,1.2,3.1,5.2,7.1,7.2,

7.3,8.1,9.1,9.2,10.1;thermalheating,2.1,6.4,7.4,9.3,9.4;wind,2.2,4.2,6.5,6.6,6.7,6.8,9.5,9.6

SolarMaxsatellite

SolarPowerSatellite(SPS)

Sorensen,Trevor

southpole(seeMoon,polesof)

SouthPole–AitkenBasin,3.1,3.2

space:difficultyofreaching,9.1,10.1;inspirationfrom,2.1,8.1;internationalcooperationon,1.1,1.2,7.1,7.2,7.3,

8.2,10.2

SpaceAct(1958)

SpaceCouncil(WhiteHouse),3.1,5.1

SpaceExplorationInitiative(SEI),3.1,3.2,4.1,4.2,5.1,7.1,10.1

spacerace,1.1,1.2,2.1,2.2,2.3,2.4,3.1,8.1,8.2,8.3,8.4

SpaceShuttleProgram,1.1,2.1,2.2,3.1,3.2,3.3,3.4,4.1,4.2,4.3,6.1,7.1,7.2,7.3,8.1,8.2,8.3,8.4,10.1;costsof,

1.2,4.4,7.4,8.5;imagingradar(SIR),8.6

SpaceStationFreedom,3.1,3.2,3.3,4.1

SpaceTaskGroup(NixonWhiteHouse)

SpaceTransportationSystem(STS),3.1,3.2

spectra,3.1,4.1,5.1,9.1

Sputnikmission,1.1,2.1

Stafford,Tom,3.1,3.2

Stanley,Doug

Steidle,Craig,5.1,5.2

StrategicDefenseInitiative(SDI),2.1,3.1,8.1

sunlightatsouthpole(seeMoon,polesof)

superposition

Surveyor3mission

Surveyorprogram,1.1,2.1

sustainability,1.1,3.1,4.1,5.1,7.1,7.2,8.1,10.1

SynthesisGroup,3.1,3.2,5.1

Taurus-Littrow

tectonism

teleoperation,1.1,6.1,7.1

terrae(highlands),1.1,2.1,2.2,2.3

thorium,6.1,9.1

tides

titanium

TotalQualitymanagement(TQM)

Toutatis(asteroid)

transcontinentalrailroad,1.1,7.1,8.1,8.2

tritium

Tsiolkovsky,Konstantin,1.1,2.1,7.1

TychoCrater

tyrannyoftherocketequation,2.1,7.1,7.2

Tyson,NeildeGrasse

Urey,Harold,2.1

vacuuminductionfurnace

VallesMarineris

vanAllenradiationbelts

Verne,Jules

Vikingmission,4.1,4.2

VisionforSpaceExploration(VSE),3.1,4.1,4.2,5.1,5.2,5.3,5.4,5.5,6.1,7.1,8.1,10.1;costof,5.6

volcanism,1.1,6.1,9.1

vonBraun,Wernher,2.1,3.1

Walker,Bob,5.1

waterontheMoon,1.1,1.2,1.3,3.1,3.2,3.3,4.1,4.2,4.3,4.4,5.1,5.2,5.3,5.4,6.1,6.2,6.3,6.4,7.1,8.1,8.2,9.1,9.2,

9.3,10.1;valueforspaceflight,5.5,6.5,6.6,9.4,9.5,10.2

Weiler,Edward

Weitz,Paul

Wells,H.G.

Wilkins,John

X-raytomography

Young,John,2.1,3.1,3.2

zero-g(seemicrogravity)

Zimmer,Bob

Zond8mission

Zuber,Maria

Zubrin,Robert,4.1,4.2