ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

Embed Size (px)

Citation preview

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    1/43

    ApolloLunarSurfaceExperimentsPackageCASE FiLECOPY

    ^ ac

    /6I ' V I I , t d r7' ! ZN

    I '1

    ei - ^63s-ALSEP PressBackgrounder

    Bendix AerospaceSystems Division

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    2/43

    The cover painting shows an astronaut .tarrying the Apollo LunarSurface Experiments Package (ALSEP) in its "barbell" configuration.The design allows an astronaut to carry ALSEP easily while maintaininghis view of the lunar surface.The frontispiece photograph illustrates a completed deployment of ALSEPas it will be carried on Apollo 12. Ribbon-like conductors link theexperiments to the Central Station. ALSEP is deployed beyond 300feetfrom the lunar module to assure its safety from the rocket blast of theastronauts" departure.

    From Daniel H. SchurzDirector of Public RelationsThe Bendix CorporationAerospace Systems DivisionAnn Arbor, Michigan 48107November 1969

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    3/43

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    4/43

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    5/43

    F O R E W O R D

    .

    ALSEP was to have been flownon Apollo 11.ecause of time anddistance constraints, astronautsArmstrong and Aldrin were given theEarly Apollo Scientific ExperimentsPackage (EASEP), which could be de-ployed 70 feet from the Lunar Mod-ule in about 10 minutes.

    To make EASEP, Bendix strippedthe proposed Apollo 13 ALSEP (iden-tical to the ALSEP for Apollo 12)and mounted the Passive SeismicExperiment to the top of the Cen-tral Station.laser ranging re-flector was installed on the palletcarrying the isotope power supply.Thermal control and antenna point-ing designs were traded off in fa-vor of ease of deployment.

    EASEP was successfully de-ployed on the Moon on July 20,1969.

    Minutes after its deployment,Earth commands turned on the Pas-sive Seismic Experiment Package(PSEP) and leveled the seismometer,which began sending reports as theastronauts walked on the lunarsurface. The seismometer recordedthe impact of articles discardedby the astronauts as they preparedto return to the orbiting commandmodule.or the remainder of thefirst lunar day, it recorded anumber of events which appeared toscientists to represent seismicactivity and/or rock slides downthe sides of nearby craters.

    ALSEP will confirm whether ornot actual seismic events or mete-oroid impacts were recorded by

    PSEP. Movement of PSEP componentsmay have been great enough to simu-late seismic activity; similarly,scientists are unwilling to con-clude whether or not there is tec-tonic activity based on the rela-tively short period during whichPSEP was reporting.

    Telemetry indicated that thethermal surfaces of PSEP were de-graded loo by the blast effect ofthe Lunar Module, but PSEP con-tinued to perform for the firstlunar day, reporting average elec-tronics temperatures up to 1900F.

    When it was shut down by Earthcommand on August 2 for the firstlunar night, PSEP had achieved 100%mission success.

    PSEP survived the lunar nightand turned on for the beginning ofthe second lunar day on August 19.On 25 August, during the secondlunar day, PSEP began to refusecommands and the instrument shutdown by itself with the darknessof the second lunar night.

    The third lunar day began onSeptember 16, and signals were re-ceived from PSEP indicating thethermal plate temperature was -520Fin the early lunar dawn. The shad-owed (west facing) solar panel re-ported -242 0 F.he PSE remainedin standby status and the systemcontinued to reject commands.

    EASEP is the subject of a sep-arate Press Backgrounder publishedby Bendix.

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    6/43

    C O N T E N T S

    `itle PageIntroduction 1Lunar Exploration 1Explorationbjectives 1ALSEPystem Selected 2ALSEPnstrumentbjectives 4

    ALSEP System Operation 7ALSEP Supporting Subsystems 7

    Electricalowerubsystem 8Passiveeismicxperiment 10Activeeismicxperiment 13Lunar Surfaceagnetometer Experiment 15Solar Wind Experiment 16Lunaronosphere Detector 17Lunar Atmosphere Detector 18Heatlow Experimentubsystem 19Charged-Particleunar EnvironmentExperimentubsystem 21

    Dustetector 22'ataubsystem 22

    Electricalowerubsystem 23Structural/Thermalubsystem 25ALSEPeployment 26Removeackages 26

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    7/43

    CONTENTS (CONT. )

    TitleageTransfer Fuel7Deploy RTG7Deploy Central Station7Deploy Experiments0

    Abbreviations

    3

    w

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    8/43

    I LLU STR A TI O N S

    Figure Title Page1 . ALSEP Stowed Configuration 32 . ALSEPeployedonfiguration 33 . ALSEPatalow 84 . Locationf ALSEP WithinheM 95 . ALSEPystemunctionallockiagram 116. Passiveeismicxperiment 127 . Activeeismicxperiment 148 . Lunar Surface Magnetometer Experiment 169 . Solar Wind Experiment 17

    10 . Lunaronosphereetector 1811. Heatlow Experiment 2012. Apollounarurfacerill 2013. Charged-Particleunar Environmentxperiment 2114. Dustetector 2215. Data Subsystem Simplifiedlockiagram 2316 . Centraltation 2417 . Electricalowerubsystem Generator Assembly 2418. Fuelaskssembly 2419. AstronautnsertinguelapsulentoTG 2520 . ALSEPeployment Timeline 28-2921. Astronautnarbellarry Mode 3022. ALSEPeployment 31

    i v

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    9/43

    TABLES

    TableitleageALSEP System Objectives2 .LSEP Deployment Configurations

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    10/43

    I N T R O DU C T I O NProject Apollo, under the

    direction of the National Aero-nautics and Space Administration,is the program designed to accom-plish the national objective ofa manned lunar landing in 1969.Project Apollo provides a varietyof approaches to lunar exploration:the astronauts will collect sam-ples of the lunar surface forreturn to Earth; they will emplacea series of scientific experimentinstruments on the lunar surface--the Early Apollo Scientific Experi-ments Package (EASEP) and theApollo Lunar Surface ExperimentsPackage (ALSEP).inally, theastronauts will traverse the Moon'ssurface, observing terrain, takingphotographs, collecting lunarsamples, and performing othermeasurements.The ALSEP System is designedto return lunar scientific datato the Earth for as long as oneyear after the astronauts' depar-ture. The data to be acquiredwill, it is anticipated, providethe scientific community withunprecedented knowledge of thelunar environment--especiallyin the areas of geology, geophysicsgeochemistry, particles and fields.

    This Backgrounder is publishedto familiarize the reader withthe principal scientific objectivesof ALSEP, the equipment, its oper-ation and its deployment on thelunar surface by the Apollo astro-nauts .L U N A R E X P L O R A T IO N

    The broad goals of lunar ex-ploration are to (1) obtain in-formationromheoono determine its environment, composi-tion a,id gross body properties,(2) utilize the unique character-istics of the Moon to establishobservatories and laboratoriesfor long-term scientific investi-gations, and (3) determine iflunar resources could be usedfor extended lunar operations,future interplanetary exploration,and terrestrial purposes.heknowledge gained from these goalswill allow not only an understandingof the Moon, but will also provideinsight into the history and evo-lutionary sequence of events inthe formation of our solar system.The Moon's proximity to Earth,its environment which providesunobstructed observation of oursolar system, and the geologicalprocess of its evolution makeit the logical first step formanned exploration of the solarsystem.EXPLORATION OBJECTIVESThe Space Science Board of theNational Academy of Sciences met atWoods Hole, Massachusetts in the summer of 1965 to study the goals oflunar exploration.t this meeting15 major questions associatedwith exploration of the Moon wereestablished.hese questionsprovide a detailed elucidationof the scientific interests:1. What is the internalstructure of the Moon?2. What is the geometricshape of the Moon?3. What is the present in-ternal energy regime ofthe Moon?

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    11/43

    4 .hat is the composition5. What magnetic fields areof the lunar surface?etained in rocks on the lu-

    nar surface?S.hat principal processesare responsible for the

    present structure of thelunar surface?

    6. What is the present patternand distribution of tec-tonic activity on theMoon?

    7 . What are the dominant pro-cesses of erosion, trans-port and deposition ofmaterial on the lunar sur-face?

    8. What volatile substancesare present on or near thelunar surface?

    9. Are there organic and/orproto-organic molecules onthe Moon?

    10 . What is the age of the Moonand the age of strati-graphic units on the lunarsurface?

    11. What is the history of dy-namical interaction betweenthe Earth and the Moon?

    12 . What is the thermal, thetectonic, and possiblevolcanic history of theMoon?

    13. What has been the rate ofsolid objects striking theMoon and how has that fluxvaried with time?

    14 . What is the history ofcosmic and solar radiationflux acting on the Moon?

    A number of scientific disci-plines contribute to the operationaltechniques necessary for lunar ex-ploration. Aside from the obviouscontributions of the geosciences(geodesy, geology, geochemistryand geophysics), other contributingdisciplines include biology, parti-cles and fields, lunar atmospheresand astronomy.ollowing the Na-tional Academy of Sciences meet-ing, the National Aeronautics andSpace Administration conducteda Lunar Exploration and ScienceConference at Falmouth, Massachu-setts to consider the specificapproaches to be taken in eachof the disciplinary areas perti-nent to lunar exploration.

    A LS E P S Y S T E M S E L E C T E DOf the lunar exploration sys-

    tem concepts investigated, themost noteworthy is the Apollo Lu-nar Surface Experiments Package(ALSEP) which was developed underthe direction of the National Aero-nautics and Space Administration(NASA), Manned Spacecraft Center.NASA selected the Bendix AerospaceSystems Division as the prime con-tractor for the design, integra-tion, test and systems managementof this scientific explorationpackage.

    The ALSEP system (Figures 1and 2) is a set of scientific in-struments which will remain onthe lunar surface after the astro-nauts' departure, and will provideimportant data on the structure,composition and characteristicsof the Moon as well as providing

    2

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    12/43

    SUBPACKAGE 1 SUBPACKAGE 2Figure 1 ALSEP Stowed Configuration

    Figure 2 ALSEP Deployed Configuration(Apollo 13)

    3

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    13/43

    advanced scientific study in areasof the solar wind, lunar atmosphereand magnetic fields.

    ALSEP INSTRUMENT OBJECTIVES

    Lunar studies will lead toa better understanding of the geol-ogy and geophysics of the Earthand will have a major impact onthe evaluation of contemporarytheories of lunar and Earth evo-lution. Measurements of physicalproperties of the lunar surfaceand interior are not ends in them-selves; they are important alsoin that they reveal the structure,composition, and state of theMoon's interior and will help toexplain its surface features.

    In a broader sense, studiesof the Moon gain significance whenviewed in the context of an evol-ving program of planetary explor-ation directed toward informationrelated to the origin and develop-ment of the solar system.

    One of the most interestingquestions to be explored with theALSEP instruments will be whetheror not the Moon evolved in thesame pattern as is now believedfor the Earth.n the Earth, rockformations include granite andbasalt - both with an almost be-wildering variety of mineral com-binations.he lunar geophysicalinformation we have thus far doesnot permit scientists to determinewhether similar lunar differenti-ation exists.LSEP instrumentsand extensive exploration of thelunar surface will provide infor-mation which may permit scientificanswers to this important question The extent of layer exposurethat exists on the Moon is alsoof scientific interest.n theEarth, this exposure results fromerosion or man's excavation.x-posure may occur on the Moon inregions of faulting and may pro-vide scientists an opportunity tostudy the layering of the rock asit occurs in depth.t is onlywith this exposure and the use ofthe ALSEP instruments (particu-larly the seismic instruments)that scientists will be able todetermine lunar subsurface charac-teristics.The ALSEP seismic instrumentswill allow a definitive study ofthe structure and tectonic activi-ty of the Moon. Two expectedsources of lunar seismic energy,moonquakes and meteroid impacts,were not definitely detected byEASEP.hus there is still noclear evidence to prove whether thmoon is seismically active or in-active.Supposing that there are moon-quakes; as the number of recordedseismic events increases, the com-pressional and shear velocity struture of the Moon may be revealedwith a precision dependent uponthe number, type, and distributionof quakes.cientists may thenbe able to answer such basic ques-tions as: (1) Is the internal structure of the Moon radially symmet-rical as the Earth, and, if so,is it differentiated?2) Doesthe Moon have a core and a crust?and (3) Is the Moon's core fluidor solid?If the Moon turns out to beseismically inactive, we will haveto rely upon meteoroid impactsand pyrotechnics to provide seis-mic energy. The ALSEP active seismi

    4

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    14/43

    instrumentillrovidealu-able lunar data resulting fromartifically produced sources ofseismic energy.ecordings ofmeteoroid impacts by an ALSEP pas-sive seismometer will provide aclear measure of meteoroid fluxdensity in the lunar environment.Recorded meteoroid impacts shouldrange from the continuous rainof small particles very near theseismic instrument to the occasion-al meteoroid of such great sizethat its impact may be measurableat any point on the lunar surface.

    Is the Moon's core a remnantof a molten body formed duringthe same period as the Earth? Ifthe core does exist, and is stillhot, it may be sustained by insu-lating layers of mantle or supple-mented by heat from radioactivedecay. The ALSEP heat flow experi-ment will determine the net flowof heat outward from the Moon'sinterior, and it may reveal theexistence of a hot core.recisemeasurements of the flow of theinterplanetary magnetic fieldthrough the Moon by an ALSEP mag-netometer instrument will tellif the Moon attracts or repelsthis interplanetary field.hedata obtained from this experimentwill aid scientists in interpre-ting the internal composition ofthe Moon.

    Determining the amount, com-position, and variation of thelunar atmosphere will greatly con-tribute to lunar geophysical in-formation.t is possible thatthe lunar atmosphere is dominatedby volcanism or other outgassingprocesses.he atmospheric meas-urements by ALSEP instruments are, therefore, directly relevant toa study of the structure of theMoon.The occasional violent outbursof protons from the Sun (relatedto the solar flares) can be stud-ied from the Moon in ways not pos-sible from the Earth.n the Eartthe solar wind cannot be studiedbecause the Earth's magnetic fieldrepels it. On the Moon, where themagnetic field gradient is signif-icantly less, scientific measure-ment of solar wind particles withALSEP instruments will be possible.Also, particles sent out by theSun set up currents through theMoon which can be monitored bythe ALSEP solar wind spectrometer.The characteristics of these cur-rents will aid in determining theconductivity of the Moon.ataon the Moon's conductivity andits magnetic properties will giveadditional insight to the compo-sition of the Moon.Finally, the role of the un-expected must not be underrated.A series of scientific experimentinstruments successfully deployedand operating on the lunar surfacemay reveal heretofore unexpectedand perhaps inexplicable informa-tion.ndeed, the course of extra-terrestrial exploration and ourunderstanding of the forces inthe universe may change dramatic-ally as the ALSEP experiments re-port their data.The ALSEP objectives listedin Table 1 are accomplished byeight experiment subsystems selec-ted by the National Aeronauticsand Space Administration to beincluded as part of the ALSEP Sys-tem.eight and volume restric-tions and the achievement of optimum

    5

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    15/43

    T A B L E 1A L S E P S Y S T E M O B J E C T I VE S

    Measurem entxperiment/Meth,%d UsedG EOPHYS ICS

    Passive Se ism ic E xperiment / long-and shor t -per iod se ism om eters wh ich detect by d is-placing an inertial m ass relative to a f ixedtransducer

    eassive Seism ic E xperim ent/t idal interpre-tation of long-period seismic m easurem entAct ive S eismic E xperim ent /ar t if ic ia l seism icenergy sources (grenade launcher assemblyand thum per device) and detection equipment(geophones)Heat Flow E xperim ent/ two heat flow probeassem blies. Probes (tem perature sensorsand heating elem ents) placed in 10-ft holesHeat Flow E xpe ri ment

    1. Natura l Se ismology(m etero id im pactsand tectonic disturbances)

    2 . Proper ties o f l unar inte rior (existencof core, m antle, etc)

    3 . Properties at shallow depths (elasticpropert ies of lunar near-surfacem aterials)

    4. Chem ical sor t ing of mant le m ater ia l( rate of heat f low outw ard from theMoon's interior)

    5 . Insulating properties of lunarsurface (conductive he at f lowthrough lunar surface)

    6. Lunar dust (dust accretion effects onust D etector/rate of dust accretion and itsthermal equilibrium of instruments)f fects on three solar cel ls oriented inecliptic plane of Sun. Solar cell outputs andt he ir temperatures, as m oni tored by th ermis tors,provide data for evaluating dust effect oninstrum entsPARTICLES AND FIELDS

    1 .nteraction of solar wind and M oon Solar W ind Exper iment / m onitor ing of par t icles(tem poral,pectral , and directional using exposed collection cups (sensors) havingcharacteristics) electrical ly ch arged grids

    8 .agnetic f ield and i ts tem poral Magnetom eter E xperim ent / t r i-axis f lux-gatevariat ions at th e lunar surface m agnetometer ins t rum ent .hree booms, eachw i th f lux-gate sensors, separated to form arectangular coordinate system and gimb alled toallow alignm ent in parallel or orthogonalconfigurations.aral lel orientation m easureslocal field gradient.lipper device provides for180-degree sensor rotation

    9 .om position of lunar atm osphere Ch arged-Part ic le Lunar Env i ronment(electron/proton energies) E xperimen t/detection and monitoring of particle

    energy levels using two sensor assem blies(analyzers)

    1 0 .unar ionosphere posi t ive ion Lunar Ionosphere D etectoridetection of positivedetect ion, (f lux, energy, and ions in lunar ionosphere and th erm alized solarveloci ty of posi t ive ions).lso w ind using a curved plate analyzer as detectorloss rate of contam inants lef t by device.eloci ty selector analyzer used toastronauts and the LM determ ine particle velocities and energies

    1 1 .unar atm ospheric pressure Lunar Atm osphere D etector / m easuresthe presence of particles for an interpretationof the densi ty of the lunar atm osphere

    6

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    16/43

    efficiency in over-all systemoperation requires a division ofthe experiment subsystems intoseparate flight systems, each con-taining four experiments distrib-uted as shown in Table 2.

    T A B LE 2A LS E P D E P L O Y M E N T C O N F I G U R A T IO N S

    APOLLO 12Experiment Sub- A N D APOLLO APOLLOs y s t e m s 1 5 1 3 1 4P a s s i v e S e i s m i c X X XActive Seismic XM a g n e t o m e t e r XSolar Wind XLunarlono- X Xs p h e r e D e t e c to rH e a t F l o w XCharged- Particle X XLunar EnvironmentLunar Atmos- Xp h e r e D e t e c to r

    ALSEP SYSTEM OPERATIONALSEP is currently scheduled

    to be included on the secondthrough fifth Apollo manned lu-nar landings.he ALSEP systemobjectives listed in Table 1 willbe achieved through the use ofeight scientific experiment instru-ments and their supporting subsys-tems.he Apollo astronauts willplace the experiment instrumentsand related subsystems on the lu-nar surface.hile in operationon the Moon, the ALSEP system willbe self-sufficient and use a Ra-dioisotope Thermoelectric Genera-tor (RTG) for electrical power.It will collect, format, and trans-mit scientific data to Earth fora period of approximately one yearafter the astronauts leave thelunar surface.ommunicationswill be maintained through the Manned Space Flight Network (MSFN).ALSEP commands will originate with-in the Mission Control Center (MCC)Houston, Texas, and will be for-warded to the remote sites of theMSFN.t these same sites, telem-etry data received from ALSEP willbe forwarded to the MCC.The ALSEP telemetry system(Figure 3) consists of two dis-tinct links.he Earth-to-Moonlink (the up-link) provides forremote control of ALSEP commandfunctions such as experiment modeselection, transmitter selection,change of subsystem data ratesand subsystem operation flexibil-ities (turn-on, turn-off, etc.).The Moon-to-Earth link (the down-link) provides for the transmis-sion of scientific and engineeringdata from the ALSEP subsystemsto Earth receiving stations.ourdifferent data transmission fre-quencies will be used to permitsimultaneous operation of fourseparate ALSEP systems.ALSEP will be deployed by theApollo astronauts in a prescribedarrangement.ach instrument willbe connected to the Central Sta-tion by flat, ribbon-like conduc-tor cabling.he Central Stationconsists of the transmitters andreceivers, the Data Subsystem,electronics for the seismic instru-ments, and a switch panel for sys-tem activation by the astronaut.A L S E P S U P P O R T I N G S U B S YS T E M SThe ALSEP system consists oftwo subpackages and a fuel caskassembly (Figure 4).ne sub-package contains three of theexperiment subsystems, the DataSubsystem, and a portion of the

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    17/43

    COMMANDSP O W E RO W E RSU BSYST E M I E N G D ATA

    COMMANDE L E M E T R YLINKIN KDATASU BSYST E M

    O T H E RIC O M M A N D S & T IM I NGLSEPSP O W E R T T_D A LUNARA T MOS PH ER ED E T E C T O RACTIVES E I S M I CH E A TF L O WPASS IVEUNAROLAR W INDUNARHARGEDSURFACEO N O S P H E R ES E I S M I CAGNETOMETERPECTROMETERE T E C T O RARTICLEE XPE R I M E N T SU BSYST E M S

    F igu re 3 ALSE P D a ta F lowElectrical Power Subsystem. Theother subpackage contains the astro-naut hand tools used for geologi-cal sampling, one of the experi-ment subsystems and the remainderof the Electrical Power Subsystem.The fuel cask assembly is the trans-portation container for the radio-active fuel capsule.

    The two ALSEP subpackages willbe mounted within the ScientificEquipment (SEQ) bay of the LunarModule (LM) for transit to theMoon.he SEQ bay is located inthe LM descent stage and is divi-ded into compartments which acceptthe two ALSEP subpackages. Thetwo ALSEP subpackages occupy avolume of approximately 1S cubic feet and, together with the fuelcask assembly and lunar hand tools,weigh approximately 280 pounds.Quick-disconnect fasteners areprovided for locking the ALSEPsubpackages in place in the SEQbay during Earth-to-Moon transitand for easy removal by the astro-naut during the lunar surface de-ployment of ALSEP.E L E C T R I C AL P O W E R S U B S Y S T E MThe fuel cask assembly is partof the Electrical Power Subsystem.It is mounted externally to theLM on the left side of the SEQbay, adjacent to ALSEP subpackage1 .hen fueled with the ra-dioactive fuel capsule, the fuel

    8

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    18/43

    FWD RLM

    \ENTERLINEFUEL CASK lLOCATION F W D eOMPART- COMPART-MENT NO. I MENT NO. Zo^AFTLM SCIENTIFIC

    EQUIPMENT BAY

    Figure 4 Location of ALSEP Within the LM

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    19/43

    cask assembly weighs approximately22 pounds.he location of thefuel cask assembly allows for in-flight radiative heat transferfrom the fuel capsule to space.A guard and shield plus specialtools provide astronaut thermalprotection during deployment.

    The Electrical Power Subsys-tem provides DC power to the dataand experiment subsystems.tcontains a SNAP 27 RadioisotopeThermoelectric Generator (RTG), apower conditioning unit (PCU) andinterconnecting cabling.he twocomponents provide all DC voltagefor ALSEP operation.elected DCelectrical outputs of the PCU aresupplied to the power distribu-tion and signal conditioning com-ponents in the Data Subsystemwhich distribute (via command dataprocessed by the command decodercircuits) DC power to: (1) heatercircuits of the data, experiment,and electrical power subsystems'thermal control elements, (2) ex-periment subsystem electronicpackages, and (3) the Data Sub-system electronics package.D A T A S U B S Y S T E M

    The Data Subsystem is the"nerve center" of the ALSEP sys-tem.t accepts the experimentsubsystem scientific and engi-neering data and encodes the datafor phase modulated RF signaltransmission to Earth.he DataSubsystem also receives commanddata from the Earth and decodesand distributes the commands tothe ALSEP subsystems.he DataSubsystem is capable of the simul-taneous reception of commands andthe transmission of data.s abackup measure to help ensure oneyear operation, redundant trans-mitters and data processor compo- nents are included in such a waythat, by MSFN command, the outputof either data processor may beconnected to either transmitter.The experiment subsystems re-ceive decoded command data fromthe command decoder, perform theirrespective lunar environmental de-tection and measuring activities,and provide scientific and engi-neering data to the data processorfor encoding and ultimate trans-mission to the MSFN.The functional operation ofthe ALSEP system is illustrated inFigure S.P AS S I V E S E I S M I C E X P E R I M E N TThe Passive Seismic Experiment(Figure 6) is designed to deter-mine the natural seismicity of theMoon.eismic energy is expectedto be produced on the Moon by tec-tonic disturbances and meteoroidimpacts.nowledge of moonquakesis essential for definition of thestrain regime of the Moon.t isalso important to know the loca-tion of quake epicenters, thuspermitting correlation of seismicevents with surface features. Inthis way, insight into the originof visible features on the Moonmay be achieved. Analysis of theform and characteristics of seis-mic waves themselves will providedata on the physical properties ofthe lunar interior.ubsurfacematerials will differ in compres-sibility, rigidity, and tempera-ture.hese differences willcause variation in seismic wavevelocities and character, fromwhich the material characteristicsmay be inferred.inally, thisexperiment will permit study of

    10

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    20/43

    UQWQ

    OW

    I

    3

    x

    U

    cn

    3

    Ia

    c4on

    a.

    rooW3

    no+roQU)xxwwIUQ

    y

    z

    u

    zro

    ro

    r

    rqQ

    BoqQ

    a-

    a

    .^,

    0o

    3 ^

    xma

    E

    E

    p

    aWW

    I

    rro

    rE

    E

    Q

    VQ

    QQv

    o

    0

    ro

    UUb

    o^

    aG

    oC

    C ^G -cb

    I

    WCWWqWwroE

    E

    E0

    oro

    O

    1

    p

    VqxUqE

    I

    zw

    ]

    G.

    Q

    coWqU

    ,LO

    x

    xGpqaQWIw

    ^

    UO

    Q

    Q"

    rc

    ro

    m"

    xWQ

    ^

    yQNbQro

    roro

    r

    ro

    ab cWQ3qzOz0

    r.

    v

    qqro

    N

    ro

    ^

    q

    aQU

    I OrorobvQvv[-uooaooQarxGmcE

    r

    QVyEVCww

    wCOL[VlQ_nnUnuT

    CawUH3

    mrWIrx1ww

    W

    WIwIIUIIoIqxIWiIIoI"Ii3`qv-LIZZNIIQjQIXIWII1WaUcEW

    LawLQLwJoWw

    xxHI

    3333t

    aaI

    En0YmmOULLE^yNwNQLOa)mL

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    21/43

    Figure 6 Passive Seismic Experiment

    the free oscillations and tidaldeformation of the Moon to providedata on the gross physical prop-erties of the Moon.

    The Passive Seismic Experimentfunctions by monitoring the dis-placement of inertial masses fromtheir zero positions relative tosensitive transducers.t containsfour sensors mounted in a singlepackage.hree of these sensorscomprise a 10- to 15-second, three-axis, orthogonal seismometer whichmonitors long-period, low-frequencyseismic energy.herefore, thisinstrument measures approximateazimuth and distance to seismicepicenters as well as monitoringlunar tidal deformations.short-period (one-half- to one-second) sensor is used to monitorthe high-frequency signal spectrum.It also serves as a backup forthe long-period instrument. The Passive Seismic Experimentis a portable 20-pound packagewhich has a shape similar to adrum rounded on one end.t isapproximately 11 inches in di-ameter and 15 inches high.heinstrument will require approxi-mately 7.5 w of power for normaloperation with a small additionalamount of power required for theheaters during the lunar night.The astronaut will place theinstrument on a small levelingstool ten feet from the CentralStation, coarse level the instru-ment manually and deploy its ther-mal shroud.he shroud (or radi-ation shield) minimizes tempera-ture fluctuations within the in-strument.The principal investigatorfor the Passive Seismic Experi-ment is Dr. Gary Latham of LamontGeological Observatory.r. Georg

    12

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    22/43

    Sutton of the University of Hawaii,Dr. Frank Press of MassachusettsInstitute of Technology, and Dr.Maurice Ewing of Columbia Uni-versity are the co-investigatorsfor the experiment.ACTIVE SEISMIC EXPERIMENT

    Artificially produced seismicevents (explosions) are a certainway of exploring the structure ofthe moon, and will complementwhatever findings are made by thePassive Seismic Experiments.

    An active seismic surveywill provide information for de-termining the structure, thick-ness, physical properties, andelasticity of surface and shallow-depth materials of the Moon.heActive Seismic Experiment (Fig-ure 7) uses explosive devicesdetonated at various distancesto measure the elastic propertiesof lunar subsurface material toa depth of approximately 500 feet.Seismic energy will be transmittedthrough lunar subsurface materialand detected by a geophone array.

    The Active Seismic Experimentcontains the seismic energy sourcesand the detection system.woenergy sources will be employed:a mortar box assembly, from whichfour explosive grenades will belaunched to detonate at variousdistances up to 5000 feet fromthe geophone detectors, and a"thumper" assembly containing21 explosive Apollo Standard In-itiator (ASI) cartridges whichwill be activated by the astro-naut at specified locations alongthe geophone line.he detectionsystem is a linear array of threegeophones together with ampli-fier systems and electronics. The thumper assembly is usedfor investigation of materialcharacteristics within a 75-footdepth of the lunar surface.tis about three feet long, andwill be folded for transportation.The upper section contains elec-tronics for the firing mechanism,the cartridge barrel, and contactpoints.he lower section isa hollow cylinder containing aplate which couples the energysource to the lunar surface andimparts seismic waves to surfacematerials for detection by thegeophones.The mortar box contains fourexplosive grenades to be activatedby Earth command near the endof the oneyear operation on thelunar surface.bout 15 incheslong, it contains electronicsand grenade launching rockets andis designed to minimize the ef-fects of recoil.ince it isnecessary to know the distancefrom the geophone array at whichthe grenade is detonated as wellas the time of detonation, thedesign provides for measurementof grenade launch angle, grenadelaunch velocity, and time of flightRefraction velocity surveysby the active seismic instrumentwill be used to study the subsur-face relations between the mariaand the highlands, possible inter-nal layering within the maria,and the existence and nature ofisostatic lunar topographic fea-tures.n a smaller scale, dataon the thickness, strength andthe variation of physical proper-ties with depth in a possiblesurface fragmental layer is perti-nent to a full interpretationof the fine structure of the lunarsurface.t is also possible that

    13

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    23/43

    A

    s

    TH UM PER

    MO R TAR PAC KAGE

    Figure 7 Active Seismic Experiment

    14

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    24/43

    surface bearing strength and thedegree of hardened subsurface mate-rials may be inferred from activeseismic refraction data.con-trolled active seismic surveywill also be of particular impor-tance in the search for water onthe Moon.ocal concentrationsof ice may be present on the lu-nar surface - beneath the depthof penetration of the diurnal heatwave.seismic velocity surveycould be used to detect the pres-ence or absence of buried ice lay-ers on the Moon.

    The principal investigatorfor The Active Seismic Experimentis Dr. Robert Kovach of StanfordUniversity. The design approachfor the thumper assembly is thatof Dr. Joel Watkins of the Mas-sachusetts Institute of Technology.

    L U N AR S U R F A C E M AG N E T O M E T E R E X P E R I M E NT

    The Lunar Surface Magnetometer(Figure 8) will measure the mag-nitude and direction of the sur-face magnetic field of the Moonand changes in the field directionup to a frequency of about onecycle per second. The placementof this ALSEP instrument on theMoon is such that the equatorialmagnetic field will be determined.Magnetic fields connected withinterplanetary space should showperiodic variations; fields as-sociated with the Moon will bestationary during the lunar ro-tation.

    As the solar wind sweeps theinterplanetary magnetic fieldagainst the Moon, some of thisfield should diffuse into the in-terior in a manner roughly anal-ogous to heat flow.y studying the surface manifestations of thisinterior field during lunar dayand night, it may be possible toinfer the electrical conductivityand magnetic permeability of thelunar interior. These quantitiesmust depend upon the compositionof the Moon and its internal tem-perature, and therefore are relatedto the origin and thermal historyof that body.f the Moon hasa small core of iron-like material,magnetic field lines diffusingin from the solar wind should "hangup" on the core and impede thediffusion. It is possible, then,to imagine a lunar magnetic fieldstreaming out through the Moonon its dark side, raising the pos-sibility of utilizing the magne-tometer for determining deep struc-ture in the Moon. Other approachesto the problem of the interiorcomposition are found by examiningthe propagation of electromagneticdisturbances which originate inthe solar wind and are carriedthrough the Moon. The responseof the Moon should be that of anegative-gain conductor.An additional purpose of thisexperiment is to monitor the pas-sage of the Moon through the mag-netic tail of the Earth. It willalso obtain specific informationon the interaction of the solarwind with the lunar surface andwhether the process results inthe generation of plasma wavesand produces some compression ofthe interplanetary field duringthe impacting of the solar plasma.Lastly, the site-surveying prop-erty of the magnetometer instru-ment allows detection of plasmacurrents and the presence of sub-surface magnetic material suchas meteorites.

    15

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    25/43

    Figure 8 Lunar Surface Magnetometer Experiment

    The scientific measurementsare performed using a three-axis,flux-gate magnetometer which con-sists of three sensors mountedat mutual right-angles on the endsof three-foot booms.he boomsare joined to an electronics pack-age which is placed on the lunarsurface.ensor rotations with-in the housing on the end of eachboom are automatically programmedand driven by small electronicmotors to provide both the scien-tific measurements and site-surveygradient measurements. The rangeof the magnetometer is adjustablewith the maximum value being 400gamma.The equatorial magneticfield of the Earth is approximately35,000 gamma.) Digital filteringtechniques are employed to reducethe noise in the output signal.The Magnetometer Experiment hasa total Earth weight of about 20pounds and will use about 10 watts

    of electrical power.he instru-ment is to be deployed by the as-tronaut about SO feet from theCentral Station.

    The principal investigatorfor this experiment is Dr. CharlesP. Sonett of the Space SciencesDivision, NASA-Ames Research Cen-ter, Moffett Field, California.The co-investigator is Mr. JerryModisette of the Space SciencesDivision, NASA-Manned SpacecraftCenter, Houston, Texas.SOLAR WIND EXPERIMENT

    The Solar Wind Experiment (Figure 9) will measure medium energyranges of the solar wind particlesThe solar wind is a flow of elec-trons, protons, and other chargedparticles from the Sun. The na-ture of the interaction of thesolar wind with the Moon is an

    16

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    26/43

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    27/43

    J00099 Wt

    Figure 10 Lunar Ionosphere Detector

    velocity, and energy per unit chargeof positive ions in the vicinityof the lunar surface.

    The LID uses two curved plateanalyzers to detect and count ions.The low-energy analyzer has a velo-city filter of crossed electricand magnetic fields.he velocityfilter passes ions with discretevelocities and the curved plateanalyzer passes ions with discreteenergy, permitting determinationof mass as well as number density.The second curved plate analyzer,without a velocity filter, detectshigher energy particles, as inthe solar wind.he LID is em-placed on a wire mesh ground screenon the lunar surface and a' voltageis applied between the electronicsand ground plane to monitor anyelectrical field effects.

    The LID will count the num-ber of low-energy ions in selected

    velocity and energy intervals overa velocity range of 4 x 10 4 cm/secup to 9.35 x 10 6 cm/sec and anenergy range of 0.2 to 48.6 ev.The distribution of ion massesup to 120 AMU can be determinedfrom these data.n addition,the electric potential betweenthe LID and the local lunar sur-fac: will be controlled by apply-ing a known voltage between theinstrument and a ground plane be-neath it.f local electric fieldsexist, they will be offset at oneof the ground plane voltage steps.By accumulating ion count dataat different ground potentials,an estimate of local electric fieldand their effects on ion charac-teristics can be made.

    In addition to low-energy ions,the LID will also measure thenumber of particles of higher en-ergies, primarily solar wind pro-tons.separate detector countsthe number of particles in selec-ted energy intervals between 10and 3500 ev. The mass of theseparticles cannot be determined be-cause the detector does not have avelocity selector.

    The principal investigatorfor the LID is Dr. John Freemanof Rice University.LUNAR ATMOSPHERE DETECTOR

    The Lunar Atmosphere Detector(LAD) will provide data per-taining to the density of the lu-nar ambient atmosphere. Of par-ticular interest will be any vari-ations of the particle densityassociated with lunar phase orsolar activity.his instrumentwill also study the effects offoreign material left by the LMand the astronauts, and rate ofloss of contaminants.

    18

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    28/43

    The instrument used for thesemeasurements is a cold cathodegauge which is mounted with theLID on Apollo 12,14 and 15 but isa separate unit on Apollo 13.hegauge produces an electrical cur-rent which is proportional to themeasured atmosphere density. Thiscurrent is amplified and read outas the instrument's scientificdata. The LAD is deployed fromits own subassembly on Apollo 13.

    When the astronaut deploysthe LID package, he removes theLAD and emplaces it three to fivefeet away from the LID.n elec-trical cable connects the coldcathode gauge instrument to theLID .The LAD package has an Earthweight of 12.5 pounds and requires6.5 watts of operating power, in-cluding power for temperature con-trol during the lunar night.

    The principal investigatorfor the LAD is Dr. FrancisJohnson of Southwest Center forAdvanced Studies.r. Dallas Evansof the Manned Spacecraft Center/NASA is the co-investigator-H E A T F LO W E X P E R I M E N T

    The Heat Flow Experiment (HFE)measures the lunar temperatureprofile at depths up to 10 feetand the value of the Moon's ther-mal conductivity over the samedepth. From these measurements,information may be deduced regard-ing the net outward flux of heatfrom the Moon's interior and theradioactive content of the Moon'sinterior compared to that of the

    Earth's mantle.t will also pro-vide data from which it is possi-ble to reconstruct the temperatureprofile of the subsurface layersof the Moon and to determinewhether the melting point may beapproached toward its interior.

    Earth heat flow measurementsand measurements of the radioac-tive content of mantle-type rocksindicate that between 10 -14 and5 x 10 -14 watts are now being pro-duced by radioactive decay in eachgram of mantle material. If meas-urements indicate that a similarrate of heat production existson the Moon, there would be strongevidence for concluding a compo-sitional similarity between theMoon and the Earth.

    The FIFE, shown in Figure 11,consists of two sensor probes anda common electronics package. Twoone-inch diameter, 10-foot holeswill be drilled into the lunarsurface by the Apollo astronaut.This will be accomplished by aspecially designed heat flow drill.A two-section probe approximately45 inches long will be loweredinto each of the two holes.heprobes contain sensors to measureabsolute temperature and temper-ature difference. Thermal conduc-tivity is investigated by meas-uring absolute and differentialtemperatures while actuating smallelectric heaters in the probes.

    The Apollo Lunar Surface Drill(ALSD), Figure 12, allows the as-tronaut to implant heat flow tem-perature probes below the lunarsurface and to collect subsurfacecore material.

    The ALSD is designed as a sys-tem which can be removed as a single

    1 9

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    29/43

    I IlD

    Figure 11 Heat Flow Experiment

    package from the ALSEP pallet andhe holes are cased to preventcarried to the drilling site.here cave-in and to facilitate inser-it will be used to drill two holes.ion of the probes of the HeatFlow Experiment. The subsurfacecore material from the second holewill be retained in the drillstring and returned to Earth ina sample return container.

    The drill is a hand held, bat-tery powered rotary percussionunit which is designed to operatewith minimum torque reaction. Whenbeing used, the drill will main-tain low temperatures at the drillbit so no coolant such as air orwater will be needed.

    Figure 12 Apollo Lunar Surface Drill

    The principal investigatorfor the HFE is Dr. Marcus G.Langseth of Columbia University.Assisting as co-principal investi-gators are Dr. Sidney Clarke of

    2 0

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    30/43

    9

    - s

    Yale University and R.M. EugeneSimmons of Massachusetts Instituteof Technology.

    CHARGED-PARTICLE LUNAR ENVIRONMENT EXPERIMENT

    The Charged-Particle LunarEnvironment Experiment (CPLEE),Figure 13, will study the energydistribution and time variationsof proton and electron fluxes in18 energy intervals over the rangeof about 50 to 150,000 electronvolts.

    Figure 13 Charged-Particle Lunar Environment Experiment

    The lunar surface may be bom-barded by electrons and protonsof the solar wind.his wind iscaused by the expansion of theouter gaseous envelope of the Suninto interplanetary space.ecausethe solar wind is supersonic andthe Moon is a large body, it ispossible that, at times, theremay be a standing shock front of the solar wind between the Moonand the Sun.he detailed physi-cal processes occurring at sucha shock front are largely not un-derstood, and they are of consider-able interest in fundamental plas-ma research.f there is sucha shock front near the moon, theCPLEE will detect the disorderedor thermalized fluxes of electronsand protons on the downstream sideof the shock front.At times of the full Moon, whenthe Moon is in the "magnetic tail"of the Earth, the CPLEE will de-tect the accelerated electronsand protons that cause auroraswhen they plunge into the terres-trial atmosphere.hese accele-ration procresses are not under-stood, and their simultaneous ob-servation near Earth and the Moonis essential for detailed study.The CPLEE will also measurethe lower-energy solar cosmic raysoccasionally produced in solareruptions or flares. The Moonis an excellent platform for suchstudies, since both its atmosphereand magnetic field are relativelynegligible.The CPLEE consists of two de-tector packages (analyzers); oneoriented vertically and the other60 0 from the vertical.ach de-tector package has six particledetectors.ive of these detec-tors provide information aboutthe particle's energy distribution,while the sixth detector provideshigh sensitivity at low particlefluxes.he particles are deflec-ted by an electrical field insidethe instrument into one of thesix detectors, depending on the

    21

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    31/43

    energy and polarity of the par-ticles.he instrument also in-cludes electronics for recordingthe particle counts and providingdata to the Data Subsystem.

    The CPLEE weighs approximatelyfour and one-half pounds (Earthweight) and requires 4.78 wattsof operating power, including powerto maintain temperature controlduring lunar night.

    The principal investigator forthe CPLEE is Dr. Brian J. O'Brienof Rice University.D UST DETECTOR

    The Dust Detector (Figure 14)will measure the accumulation andeffect of lunar dust accretionover the ALSEP Central Station.It is a 1.75-x 1.75-x 2.63-inchsensor unit, weighs approximately

    Figure 14 Dust Detector

    0.1S pound and contains threephotocells and thermistors. Thepackage is mounted on top of theCentral Station sunshield withthe photocells facing the eclipticpath of the Sun.ach cell isprotected by a blue filter to cutoff ultraviolet wavelengths below0.4 micron and a cover slide forprotection against radiation dam-age. Attached to the rear of eachphotocell is a thermistor to moni-tor the individual cell's temper-ature. The temperature of eachphotocell, compared to the antici-pated value for exposure at a givensolar angle, is a measure of dustaccretion and insulating values.The electronics for the Dust De-tector weigh approximately 0.10pound, and are mounted withinthe thermally-controlled CentralStation electronics assembly.D ATA SUBSYSTEM

    ALSEP communications are througan helical antenna attached tothe Central Station. This typeof antenna obtains high gain overa moderately narrow beam width.When deployed on the lunar surface,the antenna will be aimed at theEarth using a sun compass and ad-justment knobs. The Data Sub$ys-tem is located in the base of theCentral Station (Figures 15 and1 6 ) .

    The diplexer and switch com-ponent of the Data Subsystem pro-vides interference protection be-tween the transmitter and receivercomponents at the ALSEP antenna.It also permits alternate connec-tion of either of two transmittersto the antenna. Command data (up-link) are received by the helicalantenna and go to the command re-ceiver which demodulates the input

    22

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    32/43

    D O W N L IN K(SCIENTIFIC & ENGINEERINGUPLINK (COMMAND S)ATA)

    ANTENNA

    COMMANDRECEIVERS W I TC H IRANSMITTER( A A ND B)P OW E R

    DISTRIBUTIONUNIT

    CMD OECODERROCE SORCOMMAND S TOLECTRICALCIENTIFIC ANDEXPERIMENT ANDO W E RNGINEERING DATASUPPORT SUBSYSTEMSO ALLROM EXPERIMENTSUBSYSTEMSND SUPPORT SUBSYSTEMS

    Figure 15 Data Subsystem Simplified Block Diagramcarrier signal and provides a mod-ulated subcarrier output to thecommand decoder. The command de-coder processes the output, con-verts the command information in-to digital format and decodes thedigital information into discreteALSEP subsystem commands.on-versely, data from ALSEP subsystemsare routed to the data processor.In addition to scientific datafrom the experiments there areengineering (housekeeping) datainputs from the experiments andsupporting subsystems.lthoughmost ALSEP data are in digitalform, there are some analog datacollected.he analog data are converted into eightbit digitalwords and combined with other dig-ital data into a prescribed telem-etry format. The formatted dataare phase-modulated and routedto the transmitter, which ampli-fies, multiplies the subcarriersignals and, ultimately, sendsa 1.0-watt, S-band signal outputto the helical antenna.E L E C T R I C AL P O W E R S U B S Y S T E MThe Electrical Power Subsystemprovides all the electrical powerfor ALSEP system operation on thelunar surface for a period of at

    23

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    33/43

    Figure 17 Electrical Power Subsystem Generator Assembly

    l

    Figure 18 Fuel Cask Assembly

    1

    Figure 16 Central Stationleast one year. The major compo-nents include the generator as-sembly (Figure 17), the fuel cap-sule assembly, and the power con-ditioning unit (PCU) which is lo-cated in the Central Station. Thesupporting components include thegraphite LM fuel cask (Figure 18),the fuel cask mounting assembly,and the fuel transfer tool.

    The fuel capsule assembly (orfuel "source") uses the nuclearfuel Plutonium-238 and produces1500 watts of thermal energy.henthe fuel capsule assembly is com-bined with the generator assemblyto form the SNAP-27 RadioisotopeThermoelectric Generator (RTG),at least 63 watts are convertedby thermocouples from thermal en-ergy to electrical energy and sup-plied (at + 16 VDC nominal) tothe PCU.

    2 4

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    34/43

    r

    Thermocouples, which are nor-mally used individually to sensetemperature by converting heatto electricity, are grouped insuch numbers that a useful amountof electrical power is generated.The PCU accepts the primary + 16VDC source voltage from the RTGand performs conversion and regu-lation functions to produce sixoutput voltages:12 VDC, -6 VDC,-5 VDC, +12 VDC, +15 VDC and+29 VDC.he six output voltagesare supplied to the PCU of theData Subsystem where all switchingand distribution functions areperformed.

    Engineering data on PCU "house-keeping" functions, and six keytemperatures of the RTG, are pro-vided to the Data Subsystem fortransmission in the ALSEP telem-etry to the MSFN Earth receivingstations.

    The graphite LM fuel cask isdesigned to carry the fuel cap-sule assembly during Earth-to-Moon transit.t provides forintact re-entry of the fuel cap-sule in the event of mission abort.

    As one of the initial ALSEPdeployment tasks, the astronauttransfers the fuel capsule fromthe cask to the generator (Fig-ure 19).he fuel cask mountingassembly is tilted for access tothe cask and the fuel transfertool is used to effect a trans-fer.hermal equilibrium (i.e.,full power) of the RTG is reachedin approximately 1.5 hours.S T R U C T U R E / TH E R M A L S U B S Y S T E M

    The Structure/Thermal Sub-system consists of the support

    Figure 19 Astronaut Inserting Fuel Capsule into RTGstructure and thermal control com-ponents of ALSEP subsystem equip-ment.he function of this Sub-system is to provide structuralconfinement of the ALSEP subpack-ages within the predetermined spaceallocation and weight restrictionsof the LM, and to ensure structuraland thermal protection of ALSEPequipment in the lunar environment( - 30 0 Fto +2500F).

    Since each experiment has itsown structure and, in general,it own thermal control, the pri-mary components of the ALSEPStructure/Thermal Subsystem sup-port the Data Subsystem and theElectrical Power Subsystem.d-ditional components serve to se-cure the experiments to supporting

    25

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    35/43

    structure (and thus to the LM)during the severe loads of launchand landing.

    Subpackage 1, as stowedfor flight to the Moon, carriesthree experiments and the antennaon a honeycomb pallet which isused as a sunshield during lunaroperations.he sunshield is fas-tened to the primary structure,a shallow box having a forged-aluminum outer frame, which housesthe Data Subsystem.

    Subpackage 2 has an alum-inum pallet as the main structuralmember. The unfueled RTG (gener-ator assembly) is permanently at-tached to the pallet.emporarilyattached, in the stowed config-uration, is a subpallet carryingthe antenna aiming mechanism, theLunar Ionosphere Detector Experi-ment, and ALSEP astronaut tools.Also attached, with quick releasefasteners, are the Apollo LunarHand Tools (ALHT) in their car-rier - ready for astronaut useduring lunar geological explora-tions.

    Thermal control for the RTGis assured by removing all otherequipment from the pallet (duringALSEP deployment) and locatingthe RTG at least 10 feet from otherALSEP equipment.

    After removal of the sunshield-mounted experiments, the sunshieldis raised approximately two feetabove its stowed position to pre-pare subpackage 1 for opera-tion under lunar thermal condi-tions.pring-loaded tubular ex-tenders facilitate raising thesunshield.hermal curtains andreflectors automatically unfoldas the sunshield is raised. The fully deployed configura-tion of subpackage 1, calledthe Central Station (see Figure16), has its electronics packagesmounted on the underside of a ther-mal radiator plate and surrounded(bottom and four sides) by an in-sulating thermal blanket. Theblanket prevents heat losses fromthe electronics compartment atnight or gains during lunar daythrough any side except the radi-ator plate.he plate serves asthe main heat path, allowing radi-ative losses from the plate tospace.he radiator plate (andattached electronics packages) arefurther isolated from the lunarsurface day/night thermal cyclesby the reflectors mounted betweenthe plate and the sunshield.i-nally, the sunshield and curtainsprevent direct solar energy fromstriking the thermal radiator plateand adding to the lunar-day heatloads.A L S E P D E P L O Y M E N TThe conditions of the lunarenvironment during ALSEP deploy-ment by the Apollo astronauts (tem-perature extremes, vacuum, a one-sixth gravitational pull, and ex-treme light intensity) are moder-ated by the Extravehicular Mobil-ity Unit (EMU) consisting of apressure suit, thermal overgarment,a helmet with multiple visors,and a Portable Life Support Sys-tem.evelopment of the EMU isindependent of ALSEP but EMU char-acteristics influenced the designof ALSEP handling features.R E M O V E P AC K AG E SALSEP is inoperative duringits trip to the Moon.fter land-ing, it is deployed and activated

    26

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    36/43

    by a series of astronaut taskstogether with a series of Earthcommands to the Data Subsystemfrom the Manned Space Flight Net-work. The sequence of deploy-ment events is outlined in Fig-ure 20.eployment begins whenALSEP subpackages 1 and 2 are sep-arately removed from the SEQ bayand lowered to the lunar surface.The astronaut opens the SEQ baydoor on the Lunar Module, removesthe package restraints, and graspsa deployment lanyard which is at-tached to a boom and one subpackage.Pulling the lanyard extends theboom and allows the package tobe withdrawn from the SEQ bay andlowered to the Moon in a contin-uous motion. The other subpackageis similarly unloaded.

    TRANSFER FUEL

    The radioisotope fuel capsuleis next transferred from the fuelcask (mounted on the LM exterior)to the generator mounted on sub-package 2.his includes rotatingthe fuel cask to a horizontal po-sition, removing its dome and with-drawing the fuel capsule with thefuel transfer tool (FTT).singthe FTT as a handle, the astronautinserts the capsule into the gen-erator (refer to Figure 19), lock-ing it in place with a twistingmotion which also frees the FTT.

    The Apollo astronauts nextcarry ALSEP from 300 to 1000 feetto the final deployment site. Theprimary transport mode uses theantenna mast attached to the twosubpackages to form a "barbell"(Figure 21).simple, slip-fit,trigger-actuated lock secures themast to the subpackages.he al- ternate "suitcase" carry mode makesuse of individual handles on thesubpackages.During the traverse the astro-nauts will determine the most de-sirable, site, beyond 300 feet frothe LM, to locate ALSEP.heywill be looking for a smooth area,large enough to accommodate theplanned 100foot separation be-tween the magnetometer and theLID; a level site, free from rub-ble. The specified distance assuresthat there are no destructive LMascent blast effects on ALSEP andalso reflects the need to keepthe astronaut at all times withina safe distance for return to the in case of failure in his oxygensupply.DEPLOY RTGAt the end of the traverse,the astronaut deploys the RTG byremoving all other equipment fromsubpackage 2 and placing it in itsupright position. The RTG-to-Central Station interconnectingcable is connected to a receptaclelocated on subpackage 1.DEPLOY CENTRAL STATIONSubpackage 1, which containsthe Central Station, is deployedby placing it in an upright posi-tion 10 feet from subpackage 2,removing the experiments from thesunshield, raising the sunshield,and installing the antenna.Experiments are removed fromthe sunshield by using a UniversalHandling Tool (UHT) to releasethe tie-down fasteners and to liftthe experiments to other locations.

    2 7

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    37/43

    MIN : SEC COMMANDER ACTIVITY LM PILOT ACTIVITY00:00

    REMO VE PKG N1 MONITOR FOR SAFETY(54 SEC)

    00:54 REPORT:KG N1 OUT00:55 R E L O C A T E P K G M 1(15 SEC)

    MONITOR FOR SAFETY REM OVE PKG # 2(53 SEC)

    02:02 R E P O R T :KG #2 OU T02:03 MONITOR FOR SAFETY RELO CATE PKG N2

    (11 SE C)REMOVE ALHT

    (42 SE C)TENTATIVE

    C L O S E S E Q B A Y D O O R(01 MIN)

    REMO VE & DEPLOY ALSEPT O O L S

    OBTAIN & STOW GEO L OG ICAL01 MIN 30 SEC)T O O L S(42 SE C)04:26E P O R T : REA D Y FOR FUELT RAN S F E R

    04:27ONTINUE STOW INGGEO LOGICAL TOOLS

    RO TATE PKG f2 UPRIGHT &REMO VE SUBPALLET

    (40 SE C)MONITOR F OR S AFETY &OTATE FUEL CASKSUPPLY TOOLS43 SEC)ENTATIVEEMOVE CASK DOME( 26 SEC)TRANSFER F UEL CAPSULE(01 MIN 08 SE C)07:24EPORT: R T G F U E L E D

    07:25SSE MBLE BARBELLRETRIEVE SUBPALLETONF IGURAT ION

    (16 SEC)27 SEC)0752EPORT: START OF TRAVERS E07:53ARRY S UBPALLET & ALHT

    LEAD TRAVERSEARRY BARBEL LPICK ROUTERES T AS NECESSARYEST AS NECESSARY( 5 M IN 52 SE C)5 M I N 5 2 S E C )1 3 : 4 5E P O R T : TRAVERSE COMPLETErF igu re 20 ALSE P D ep loym en t T im e li ne28

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    38/43

    MIN : SE COMMANDER ACTIVITYM PILOT ACTIVITY1 3 : 4 6

    TEMPOR ARILY EMPLACEEPLOY MAST/PKG M1SUBPALLET & ALHT22 SEC)

    (14 SE C)IT E N T V

    DEPLOY PKG M2(01 MIN 10 S E C )ONITOR FOR SAFETYCONNECT RTG TO CE NT STA(02 SEC)1 5 : 1 2R T G PL U G I N1 5 : 1 3

    DISCONNECT & S T O W MASTEMO VE L ID /LAD &(0 1 MIN)ONNECT CABLE

    (41 SE C)ACTIVATE RTG SW

    ( 2 SEC)1 6 : 1 31 6 : 1 4

    RO TATE PKG # 1(14 SEC)

    REL EASE SWS( 32 SEC)

    RELEA S E PS E(32 SEC)

    R E M O V E L S M(54 SEC)

    RELEA S E S UNS H I ELD(03 MIN)

    DEPLOY SUNSHIELD( 53 SEC)

    ASSEMBLE ANTENNA(02 MIN 06 SE C)

    CONF IRM: AZ /EL S ET T ING(02 MIN 07 S E C )

    ACTUATE SW -1REQ UES T : XMTR ON

    I F A LS EP D OE S NOT RES POACTUATE S W -2 AND S W - 3

    R E P O R T : SW POSIT IONS

    D E P L O Y P S E S T O O L(18 SEC)

    D E P L O Y S W S(01MIN 22 SEC)

    REPO RT: AL IGNMENT COMPLETED E PL O Y PS E

    (01MIN 05 SE C)

    RE POR T: AL IGNMENT VALUESDEPLOY LSM

    (02 MIN 34 SE C)REPO RT: AL IGNMENT VALUESDEPLO Y L ID

    (03 MIN 42 SE C) I

    OBTAIN ME TRICPHOT OGRA PHS O FDEPLOYED ALSEPD

    RET URN TO LME T U R N TO L MFigure 20 (Continued)29

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    39/43

    Figure 21 Barbell Carry Mode

    After the experiments are re-moved, additional tie-down fasten-ers holding the sunshield are re-leased using the UHT.pring-loaded tubular extenders raisethe sunshield and the thermal cur-tains unfold automatically alongwith the reflectors.

    Antenna installation involvesattaching the assembled mast tothe Central Station, mounting theaiming mechanism on the mast, andinstalling the antenna on the aim-ing mechanism. Antenna alignmentis accomplished in four steps:

    1 .eveling the base of theantenna aiming mechanismusing thumb screws and anintegral bubble level 2 . Aligning the antenna aim-ing mechanism with respectto a shadow; i.e., estab-lishing an East-West ref-erence.his alignmentuses an adjusting knob,shadow post, and paintpattern3. Entering coarse and fineelevation settings in theaiming mechanism using anadjustment knob with twoscales4 . Entering coarse and fineazimuth settings in thesame manner.Values for these settings are ob-tained from pointing tables whichdepend on lunar latitude and longi-tude and may be relayed to theastronaut from the Earth.heastronauts report completion ofalignment and request Earth com-mands for ALSEP activation.DEPLOY EXPERIMENTSFigure 22 shows ALSEP as itwill be deployed for Apollo 12.The Passive Seismic Experimentis emplaced ten feet East (orWest) of the Central Station, dir-ectly opposite the RTG.he astro-naut places the sensor assemblyon a small stool, deploys the ther-mal shroud, levels the sensor onthe stool (within 5), reportsthe shadow alignment, and returnsto the Central Station.The Solar Wind Experiment isplaced 14 feet South of the Cen-tral Station.he astronaut30

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    40/43

    - 3 0 0-F T M IN IM U M B AS E D O NLM ASCE NT BLAST W ITH

    100 % S AFETY FACTORP AS S IV E S E I S M I C2a R T G0 FT =10 FT0 F T//p13 FTAGNETOMETER1 SOLAR WIND

    55 FTPECTROMETER EWLUNARI ONOS PHER ED E T E C T O RLUNAR ATMOSPHE RE D ETECTORF igu re 22 ALSE P D ep lo ym en textends its legs, sets the instru-he astronaut will then reportment on the lunar surface, andhe alignment and return to thealigns it relative to a shadowentral Station.pattern.The Lunar Surface Magnetometeris placed 55 feet from the CentralStation in a direction away fromthe LM.ts interconnecting cableis deployed during the 55-foottraverse.pon arrival at themagnetometer location, the astro-naut unfolds the legs, places theinstrument on the surface in ap-proximately the proper East-Westalignment, unfolds the booms whichcarry the sensors, and makes finalleveling and alignment adjustments. The astronaut next carriesthe Lunar Ionosphere Detector 55feet, simultaneously deployingthe interconnecting cable, to aposition at least 80 feet fromthe Magnetometer.efore emplac-ing the LID, the astronaut re-moves a wire mesh "ground plane"and places it on the lunar surface.Next, the astronaut removes theLunar Atmosphere Detector from theLID and places it off the edgeof the ground plane in a directionaway from the Central Station andthe LM.inally, he lowers the

    31

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    41/43

    instrument to the surface, in thecenter of the screen, and levelsand aligns it.bubble leveland shadows are used for establish-ing alignment.

    The second and third flightsof ALSEP contain different experi-ments as shown in Table 2.

    If the Active Seismic Experi-ment is included, the mortar boxassembly is deployed first.tis placed 10 feet from the CentralStation, pointing away from theanticipated geophone line.hethumper/geophone assembly is thencarried along the preselected lineThe geophone cable has three geo-phone detectors wired to it insuch a way that the astronaut caninsert the geophones in the lunarsurface at distances of 10 feet,160 feet, and 310 feet from theCentral Station.hen the astro-naut returns along the geophonecable he fires the cartridge-actu-ated thumper at 15-foot intervals(21 cartridges).

    Deployment of the Heat FlowExperiment requires the drillingof holes for the heat flow probes.Using the Apollo Lunar Surface

    Drill, two holes are drilled ap-proximately one-inch diameter and 1feet deep.he 45-inch-long probesare placed in the bottoms of thedrilled holes by means of a spe-cial tool.he probes are con-nected by cables to an electron-ics package which is, in turn,cable-connected to the CentralStation.he astronaut placesthe electronics package on thesurface with a prescribed align-ment which satisfies thermal (sun-shield) requirements.

    The Charged-Particle LunarEnvironment Experiment is emplacedten feet from the Central Station.The astronaut will set it on thelunar surface, level the instru-ment to within 5 degrees of ver-tical, and align it to within 2 degrees with respect to shadowlines on the instrument.

    With the ALSEP deployed andactivated, the astronauts may returto the LM or continue other lunarsurface mission tasks such as geo-logical surveys.

    3 2

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    42/43

    ABBREVIATIONSAbbreviation Definition

    A/D AnalogoigitalA EC Atomic Energy CommissionALGE ApollounareologicalquipmentALHT Apollounarand ToolsALSD ApollounarurfacerillALSEP Apollounar Surface ExperimentsackageAMU Atomic MassnitA S E ActiveeismicxperimentA S I ApollotandardnitiatorCCGE Cold CathodeaugexperimentCCIG ColdathodeonaugeCPLEE Charged-Particleunar EnvironmentxperimentEMU Extravehicular Mobility UnitEng. EngineeringHF E Heatlow ExperimentLM Lunar ModuleLS M Lunar Surface MagnetometerMCC MissionontrolenterMod ModulatedMSFN Manned Spacelight NetworkNASA Nationaleronauticsnd Space AdministrationPCU PoweronditioningnitPWR PowerR.F. RadiorequencyRTG Radioisotopehermoelectricenerator

    33

  • 8/6/2019 ALSEP Press Backgrounder. Apollo Lunar Surface Experiments Package

    43/43