Small Submarine Basing of MX

Chapter 5

SMALL SUBMARINE BASING OF MX

Chapter 5.— SMALL SUBMARINE BASING OF MX

Submarine Basing of Strategic

Nontechnical Considerations

Technical Choices Leading to

Page

Missiles .. .167

. . . . . . . . . . 167

Small Submarines . . . ............169

Description and Operation of the SmallSubmarine System. . . . . . . . . . . . . .170

Introductory Remarks. . . . . . . ........170Overview . . . . . . . . . ...............171Communications System and

Operational Procedures . ..........173Submarine Navigation and Mapping

Needed for High Missile Accuracy .. .174Missile Guidance Technologies . . . . . . .175

Vulnerability. . . . . . . . . . . . . . . . . . . . . . . .176Tactical and Strategic Applications of

Antisubmarine Technologies . . . . .. 177Theory of Open Ocean Barrage . . . . . . .178Open Ocean Barrage With No

Information About SubmarineLocations . . . . . . . . . . . . . . . .. ....179

Open Ocean Barrage After Detectionof Snorkeling Submarines . . . . . . . . . 180

Searches With Technologies ThatObserve Nonsnorkeling Submarines. .182

Increased Range Acoustic Technologies. 184

Page

Increased Radar Search Using Satellites. 186Countermeasures to Radar Satellites .. .189War of Attrition . . . . . . . . . . . . . . . . . .189Van Dorn Effect . . . . . . . . . . .. ...190Theory of Trailing. . . . . . . . . . ........191Establishment of Trail at Port Egress. . .193Establishment of Trail Using Large Area

Open Ocean Search . . . . . . . . . .196Diesel-Electric Propulsion Technology. .197Nuclear Electric Propulsion . . . . . . . .198Concluding Remarks on the

Vulnerability of Submarines . . . . .199

Factors Affecting the Accuracy of Land-and Sea-Based Missiles . . . . . . . 199

Accuracy of Small Submarine Based MX .. 202

Accuracy of Star-Tracker-Aided InertiallyGuided MX . . . . . . . . . . . . . . . . . . . . .205

Degradation in Accuracy After aSubmarine Navigation Fix. . . . . . .. ..206

Inertial Guidance Aided by Radio Update .207

Time on Target Control. . . . . . . . . . . . . . . .208

Responsiveness of the Submarine Force. . .209

Endurance of Force. . . . . . . . . . .210

Cost and Schedule . . . . . . . . . . . . . . . . .

System Size. . . . . . . . . . . . . . . . . . . . . . .

Final Sizing Consideration . . . . . . . . . . .

Location and Description of Bases. . . . .

TABLES

Tab/e No.21. SubmarineObservables . . . . . . . . . .22. Acoustic Sensors forSubmarine

23

24

25

26

27

28

29

Detection . . . . . . . . . . . . . . . . . . . . .Nonacoustic Sensors for SubmarineDetection . . . . . . . . . . . . . . . . . . . . .Operational Factors Affecting RadarSearch of Submarine DeploymentAreas. . . . . . . . . . . . . . . . . . . . . . . . .Miss Sensitivities tolnitial Errors forICBMTrajectories. . . . . . . . . . . . . . .Comparisonof Hard Target KillCapabilities of Sea-Based MX WithDesign Requirements of the Land-Based MX . . . . . . . ., . . . . . . . . . . . .Small Submarine 10-Year Lifecyclecost. . . . . . . . . . . . . . . . . . . . . . . . . .Number of Submarines Required To

Page

. . 210

. . 212

. . 213

. . 213

Page. . 177

. . 177

. . 177

. . 182

. . 201

. . 203

. . 211

Keep 100 MX Missiles Continuously onStation v. Submarine In-Port Time .. ..213Estimated Characteristics of the SmallSubmarine Refit Site and the TridentRefit Site. . . . . . . . . . . . . . . . . . . . . .. .214

FIGURES

Figure No. Page67, Nuclear and Nonnuclear Powered

6869

70

71

Submarines of Different Size . .......171Encapsulated MX Missile . ..........172MX-Carrying Diesel-Electric SmallSubmarine. . . . . . . . . . . . . . . . . . . . . .. 173Sequence of Events During theLaunch of an Encapsulated MX Missile. 173Number of Weapons Required to

Figure No. Page

72.

73.

74.

75.76.77.7879

80

8182

83.

84.

85<

86,

87

88

Destroy Submarines That Have BeenSighted Prior to a Preemptive Attack .. 179Potential Deployment Area Given1,000- and 1,500-nmi Operating Ranges 180Large Area Search With TechnologyThat Can Only Detect SnorkelingSubmarines. . . . . . . . . . . . . . . . . . . . . .181Sources of Reverberation That Limitthe Capability of High-Powered ActiveSonars. . . . . . . . . . . . . . . . . . . . . .. ...183Potential Whale Sonar Targets . ......185Fishing Vessel Monitoring, ., . .......187Ground Track of Radar Search Satellite 188Van Dorn Ef fect . . . . . . . . . . . . . . . . . .191Active Acoustic Search for aSubmarine That Has DispensedDecoys Which Simulate a RefIectedSonar Signal From a Submarine Hull. .. 194Passive Acoustic Search forSubmarine That Has DispensedDecoys Which Simulate the Soundof a Submarine . . . . . . . . . . . . . . . . . , .195German Type 2000 Submarine . ......197Factors Affecting the Accuracy of aBallistic Missile. . . . . . . . . . . . . . . . . . . 200Down Range and Cross Range Errorsof a Ballistic Reentry Vehicle at aTarget . . . . . . . . . . . . . . . . . . . . .. ....202Accuracy of Inertially Guided Sea-Based Missile at Different RangesFrom Targets. . . . . . . . . . . . . . . . .. ...202Accurary of Star-Tracker-EnhancedSea-Based Missile as a Function ofRange From Target . . . . . . . . . . . . . . . .206Ocean Areas That Provide AdequateLine-of-Sight View of Ground Beaconson Continental U. S., Aleutian Islands,Alaska, and Hawaii . . . . . . . . . . . . . . . .208Ocean Areas That Provide AdequateLine-of-Sight View of Ground Beaconson Continental U. S., Aleutian Islands,Alaska, Hawaii, and Selected South SeaIslands. . . . . . . . . . . . . . . . . . . . . . . . . . 209Small Submarine Program Schedule. .. 211

Chapter 5

SMALL SUBMARINE BASING OF MX

SUBMARINE BASING OF STRATEGIC MISSILES

Strategic missiles are based on submarinesbecause submarines can be hidden in vast ex-panses of ocean, thereby gaining a high degreeof survivability. Currently, the United Statestakes advantage of the survivability of subma-rnes to deploy the Polaris, Poseidon, a n dTrident I missiles. Unlike attack submarines,whose primary mission is to protect convoys orattack enemy shipping, these balIistic missilecarrying submarines seek to avoid surfaceships and remain undetected, available forstrikes against enemy targets on command.The object of basing MX on submarines wouldbe to take advantage of the same survivabilitythat has been demonstrated by experiencegained with the Polaris and Poseidon systems.One major question addressed in this chapteris whether this survivability can be expected tocontinue into the 1990’s

MX has been conceived as a land-basedintercontinental ballistic missile (I CBM). Theland-based ICBM has historically had greateraccuracy, flexibility of targeting and rapidityof response than that of sea-based missiles. Asa land-based ICBM, the MX missile is expected

to set still a new standard in each of these at-tributes relative to previously deployed land-based missiles. The second technical questionthat is to be addressed in this chapter is the ex-tent to which this new standard of attributescould be preserved if the MX were insteadbased on submarines.

Deploying the MX at sea rather than on landwouId also raise questions about how impor-tant it is to mix and balance the different at-tributes of nuclear forces to best deter war.The different points of view are summarizedhere, but these issues cannot be resolved bytechnical anaIysis.

This chapter begins by noting some of theprinciple rationales and drawbacks of sub-marine basing of MX. Some of these issues,while clearly relevant, are just as clearly nottechnical issues per se. The following sectionsattempt to more closely define and analyzetechnical and operational issues that bear onthe problem of submarine deployment of alarge, flexible, counterforce ICBM like MX.The conclusions of these technical analysesare summarized in the last section.

NONTECHNICAL CONSIDERATIONS

Much of the interest that has been shown insubmarine basing of MX is motivated by theperception that the survivability of a futuresubmarine force is Iikely to be insensitive tothe nature and size of the Soviet ICBM force.As long as the Soviets are not able to developan ability to localize and track submarines, theonly conceivable way they could preemptivelyattack the submarine force with ICBMS wouldbe to randomly barrage suspected submarineoperating areas. If the Soviet ICBM force wereto grow in its ability to deliver large amountsof megaton nage, submarine operating areascould merely be expanded in size to countersuch a threat. I n addition, the Soviets could

gain no additional ability to threaten the sur-vivabiIity of submarines through improve-ments of accuracy technology or through frac-tionating the warheads on existing or newICBMS. Thus, provided that submarines main-tain their ability to hide in vast expanses ofocean, there would be little or no way tothreaten their survivabi l i ty with ei ther asubstantial expansion, or wi th technicalimprovements, of Soviet ICBM forces. A deci-sion to deploy the MX missile at sea in sub-marines would therefore negate the effec-tiveness of the Soviet ICBM force as a meansof threatening the MX missile. This decisioncould diminish the political leverage that the

167

168 ● MX Missile Basing

Soviets have bought with their modernizedICBM force by removing their abi l i ty tothreaten a major U.S. strategic weapon system.

A perspective that argues against the basingof MX on submarines holds that moving mis-siles off the land will result in fewer disincen-tives to an adversary who is contemplating theuse of, or the threat of using, nuclear weaponsas a means of extracting political concessionsfrom the United States. This perspective viewsthe basing of strategic missiles on land as in-surance against political blackmail. An adver-sary who attempts to gain political advantageby threatening U.S. strategic systems withnuclear destruction would, in effect, be forcedto threaten targets on American soil. Land-basing would make the price of attempts togain political leverage in this manner veryhigh, thus decreasing the likelihood of suchblackmail.

Some who argue this way also believe thatthe United States wouId lack the resolve to re-spond to Soviet threats unless it was clear thatthe continental United States was threatenedwith nuclear attack, They fear that such lackof resolve could make nuclear war easier foran adversary to contemplate, thereby makingit more Iikely.

Others disagree with these perspectives andargue that there is a beneficial effect of remov-ing potential targets from the continentalUnited States. Since there would be no cleargain in an unsuccessful attack against a surviv-able sea-based system, there would be no in-centive to attack strategic systems. They arguethat a land-based system that presents aserious threat to Soviet military systems couldinvite attack if a crisis deteriorated to thepoint where Soviet decisionmakers believedwar was unavoidable. I n such a circumstance,Soviet decisionmakers might attempt to limitdamage to their own systems by striking first.If a submarine-based system were untarget-able, a rational Soviet decisionmaker wouldbe denied such a choice. Thus, submarine bas-ing wouId have the stabilizing effect of forcinga wait-and-see attitude on decision makers dur-ing periods of international crisis.

A potentially serious drawback of basing MXmissiles on submarines is that the system couldshare a common mode of failure with Tridentand Poseidon if an unforeseen antisubmarinewarfare capabiIity emerged in the next 20years. Since the United States, with its substan-tial commitment to undersea warfare, hasbeen unable to identify or project any threat toballistic missile submarines, the significance ofsuch a potential drawback is difficuIt toevaluate.

Another potential drawback is that a subma-rine-based system would require highly skilledand trained personnel that are not currentlyavailable in the Navy. In order to meet addi-tional manpower needs, training centers wouldhave to be established and recruiting effortswould Id have to be expanded. I f the civiIianeconomy was healthy, competition for train-able people could make it difficult to attractthem into the Navy. It could also be difficult toretain personnel once they have developedskills because of the attraction of lucrativeciviIian jobs.

‘Submarine construction presents somewhatdifferent problems from that of surface shipconstruction. Past experience indicates that ifshipyards do not demonstrate a good deal ofcompetence constructing surface ships, theywiII have very great difficulties constructingsubmarines. Since the volume available forequipment and crew in a submarine is verysmall relative to that available on surfaceships, construction must be carefully plannedso that components can be put into crampedlocations in the proper sequence. Quality con-trol is also important since equipment andcomponents may be subjected to extreme con-ditions during the course of submarine opera-tions.

Constructin g a new fIeet of MX-carrying sub-marines wouId be a major undertaking. Threeshipyards not currently engaged in submarineconstruction would probably be needed toconstruct submarines if the full fleet is to bedeployed by 1992 or 1994. Each shipyardwouId have to be provided with a smalI teamof people experienced in submarine construc-

Ch. 5—Small Submarine Basing of MX ● 169

tion to help it make an orderly transition tosubmarine construction. Lack of experience insubmarine construction couId resuIt in pro-gram delays if the shipyards had not beencarefulIy chosen for their efficiency and com-petence or if they did not have adequate guid-ance on submarine construction techniques

Delays could occur in other submarine con-struction programs as well, if the base ofspecial materials required for submarine con-struction were not expanded to meet increaseddemands. It is also possible that if problemsdeveloped within the MX submarine program,talent, effort, and funding might also have tobe diverted from those programs.

Other problems could ar ise with otherelements of the project due to the timing ofthe missile development program If missiledevelopment were delayed a year by designchanges required for sea basing, it would beready for deployment in 1987 The design,development, and construction of a new class

of submarines could in theory be expedited toproduce lead ships by late 1987, but this ap-pears unlikely. If the program proceeded at arate more characteristic of recent strategicweapons programs, the lead ships would notbe deployed until 1990. The missile couldtherefore be ready for deployment severalyears before there are means to deploy themissile. It would be necessary to keep missilescientists, engineers, and managers availablefor the testing and monitoring phase of themissile deployment. These individuals mighthave to be retained at great cost until thedeployment is far enough along to assure thatunforeseen problems had not emerged.

These perspectives, among others, involvejudgments of a nontechnical nature and willnot be addressed further in this chapter. In-stead the focus will be on assessing the tech-nical strengths and weaknesses of a sea-basedMX system that was optimized to perform themissions usually ascribed to ICBMS.

TECHNICAL CHOICES LEADING TO SMALL SUBMARINES

If an MX-carrying submarine force is to bespecificalIy optimized to capture as many at-tributes of the land-based lCBM as possible,there are two attributes of the land-basedI C BM that suggest smaII submarines carrying afew missiIes are preferable to large submarinescarrying many missiles These attributes of theland-based missile are

1. fIexibility of targeting that does not com-promise survivability of unused missiIes inthe force, and

2. diversity in failure modes with the otherlegs of the Triad

Flexibility refers to a weapons system’s abili-ty to select and carry out preplanned attackoptions, or attack options that are subsets ofpreplanned attack options It also includes theabiIity to carry out ad hoc attacks against tar-gets that may be on the National Target DataInventory List or targets that are specified onlyin terms of geographical location

Since a large ballistic missile submarine car-ries military assets capable of delivering enor-mous destruction against an adversary’s tar-gets, it is itself a target of considerable militaryimportance, I f the submarine’s position wereto become known in wartime, there wouId be asubstantial incentive to attempt to destroy it.

If a flexible tar-getting strategy were adoptedfor a submarine force, submarines might beordered to fire a Iimited number of missiles atenemy targets. The firing of these missiIescould potentialIy reveal the position of thesubmarine to enemy surface ships at great dis-tances, to space-based sensors, radar systems,and possibly even sonar systems. The expectedpostlaunch survivability of a missile-carrying

submarine is therefore quite different fromthat of its expected prelaunch survivabilityThe flexible use of this force could thereforeresuIt in attrition that wouId compromise itsabiIity to continue the war or force termina-tion of the war


If flexibility of targetting is specificallydesired in a submarine force, it would be nec-essary to make the survivability of remainingmissiles as independen t o f previouslylaunched missiles as possible. This could bedone if the submarine force was made up of alarge number of submarines each carrying asmall number of missiles. If this were the case,then the wartime loss of submarines thatplaced themselves at risk by launching only afew of their missiles would not result in theloss of a large number of remaining unusedmissiles. The force would therefore be able tocarry out limited nuclear attacks without com-promising its ability to carry out subsequentmassive strike missions.

Another reason that submarine-based strate-gic weapons have been less flexible than land-based ICBMS in the past is that communica-tions with submarines have historically notbeen as good as those achievable with land-based systems. As will be discussed later in thischapter, f lexibi l i ty in targett ing could beachieved with the current submarine force if aconscious decision were made to acquire cer-tain kinds of communications capabilities andto adopt certain operational procedures.

Diversity in failure modes with other legs ofthe Triad is a more di f f icul t at tr ibute to

discuss, since it involves making judgmentsabout threats that have not yet been iden-tified. If the MX missile were deployed onsmall submarines, it seems more probable thatit would share a common failure mode withother submarine-based systems than would aland-based system. The likelihood of such abreakthrough must be considered remote inthe absence of any scientific evidence to sup-port such a possibility. However, if an unfore-seen antisubmarine capability developed inthe future, it is possible there could be quan-titative and/or qualitative differences betweensea-based Trident/Poseidon submarine forcesand submarine-based MX that could make thethreat less effective against such diverse typesof submarines. Small, slow-moving submarineswould in fact have certain signatures that aredifferent from those of larger, faster movingsubmarines. In addition, a fleet of many sub-marllnes poses both a qualitatively and quan-titatively different set of operational problemsto an antisubmarine force than does a fleet ofa few submarines. With this in mind, it couldbe argued that a fleet of MX-carrying sub-marines would increase the diversity of stra-tegic nuclear forces, making it less likely that asingle technology could threaten all three legsof the Triad.

DESCRIPTION AND OPERATION OFTHE SMALL SUBMARINE SYSTEM

Introductory Remarks

If the MX were to be deployed on a fleet ofsubmarines, there wouId be many engineeringand operational tradeoffs that would have tobe made if the fleet was to be an effectiveweapon system. 1 n order to establish conserv-ative bounds for what is Iikely to be achiev-able, OTA has postulated a system of subma-rines, operational procedures, and communi-cations that is specifically optimized to attainICBM-like flexibility and responsiveness whilestill basing MX on submarines. The system con-cept to be described and evaluated is based on

off-the-shelf technologies, and Navy oper-ational experience and practices whereverpossible. However, it should be expected thatif a national decision were made to deploy MXon submarines, many technical features of anew system of MX-carrying submarines wouldlikely be different from those postulated forOTA’S analysis of small submarine basing. Anew class of submarines would have to bedesigned and built. New and different pro-cedures would also be evaluated and devel-oped for the submarine operations. Such a vastenterprise as the design, construction, anddeployment of a new and modern strategic


weapon svstem could result in a system with rines to carry 100 alert MX missiles for deliveryfeatures differentdiscussed here

from the system that will be of highly accurate warheads against Soviettargets. It is believed that these submarines,

Overview

The submarine system to be described uses acombination of communications, navigation,and guidance technologies aimed at maximiz-ing flexibiIity of targeting, rapidity of re-sponse, and missiIe accuracy. Submarine oper-ational procedures are set up to allow sub-marines to carry out launch orders issued bythe National Command Authorities (NCA) rap-idly. There would always be enough subma-

while at sea, would be untargetable and im-pervious to Soviet preemptive actions (thisissue is discussed fully in the next section) Thissubmarine force is therefore optimized tocarry out missions similar to those commonlyascribed to ICBM forces.

The basing system would consist of a forceof 51 moderate-sized (see fig. 67) diesel-electric submarines each of which is armedwith four MX missiles. The submarines couldalso be powered with small, low-enrichment

Figure 67.—Nuclear and Nonnuclear Powered Submarines of Different Size

Nuclear poweredNR-1136’ X 13’

Nuclear poweredTrident42’ X 560’

OTA diesel-electric25’ X 342’

German Type 2000small diesel-electric25’ X 200’

Nuclear-turboelectricSSN-597 (Tullibee)

SOURCE: Office of Technology Assessment


nuclear reactors. During normal operations, 28submarines would be continuously at sea, Inperiods of crisis or international tension, sub-marines in refit (but not those in extended refitor in overhaul) could be surged from port toraise the at-sea numbers to 38 to 40. Thisdeployment would provide an additional 400warheads on station.

The MX missiles would be carried in steelcapsules approximately 80 ft long and 10 ft indiameter (see fig. 68), The capsules would becarried outside the pressure hull on the topside of the submarine’s huII (see fig. 69).

On a launch command (see fig. 70), hy-draulic actuators would open doors on the sub-marine’s fairings and straps within the fairingswould release the capsule. Soft ballast wouldthen be blown from the front end of the cap-sule causing it to rise and rotate toward thevertical. Upon sensing the ocean surface, thetop and bottom caps on the capsule would becut free, the missiles motors would ignite, and

the thrust of the first stage motor would propelthe missile from the capsule.

After missile flyout, a flotation collar and/ordrag surface would deploy from the e m p t y

capsule to slow its descent into the ocean. Thiswou Id lower the risk of a COIIision between theexpended capsuI e and the submarine.

The submarines would deploy from dedi-cated bases in Alaska and on the east and westcoasts of the continental United States, Eachbase would, on the average, have 5 to 6 sub-marines in port at al I times. The submarineswouId be at sea for 60 days and in port for refitand logistic support for 25 days.

The submarines would typically operate asfar as 1,000 nautical miles (nmi) from port.They would be designed to have sufficientspeed and endurance to operate at stiII greaterdistances from port (1 ,500 nmi or more) if suchoperations were deemed desirable. Each sub-marine would have an advanced submarine

Figure 68.—Encapsulated MX Missile

Shock isolation

Steel capsule

Small-diesel

Trident

SOURCE. Off Ice of Technology Assessment


Figure 69.— MX”Carrying Diesel. Electric Small Submarinea (3,300 tons submerged displacement)

Computer

Engine room Galley messing- - - - -

T l a u n c h T

Communicaton

Forward

II I

aSubmarlne design developed by consfdenng the characteristics of the most recent U S,.bwlt diesel submarines, the SS580, the SSG557 GROWLER Class REGULUSmlssl Ie submarine, current technology represented In the Federal Republ IC of Germany submarine designs (H DW Type.209 and Type-2000 designs), and other advancesdemonstrated In Swedwh and Nethedand designs Proven technologies incorporated Into design are maximum quletlng achewable by sound fsolation, a(r coupling ofelectrtc drive motor to screw shaft, faster recharging at lower snorkel noise levels, Increased battery capacity, microprocessor monitoring and management of powersystems, and smaller crew size

SOURCE Off Ice of Technology Assessment

Figure 70.—Sequence of Events During theof an Encapsulated MX Missile

A

Launch

- “t ’

SOURCE Office of Technology Assessment

inertial navigation system (E SCM/SINS), avelocity measuring sonarsystem for interrogatingspenders, and equipmentthe Global PositioningLORANC.

(VMS), an acousticprepositioned tran-for taking fixes onSystem (GPS) and

Missile accuracy would be maintained main-ly with onboard submarine navigational equip-ment. This equipment would occasionally beupdated with the G PS or a covert system ofacoustic transponder fields. If the GPS weredestroyed by enemy action, the occasionalnavigational updates would be done with theacoustic transponder fields.

Communications System andOperational Procedures

The communications system and operatingprocedures would be configured so that thesubmarines in peacetime would constantly bereceiving communications from NCA through


trailing wire antennas and/or buoys that wouldconstantly receive shore to submarine very lowfrequency (VLF) communications. In addition,the submarines could also be in two-way com-munications with NCA using a covert, rapidand reliable high-orbit satellite transponderlink. This link would allow for the submarinesto report back to NCA and make possible highdata rate reception of information for rapidretargetting of the force.

Since shore-based VLF stations would prob-ably be destroyed if there was enemy preemp-tive action, communications with the sub-marines would then be maintained via sur-vivable airborne VLF relays, that could imme-diately replace shore-based VLF stations.These airborne relays would maintain radiosiIence and would be continuously airborneunless they were needed to replace shore-based VLF transmissions. Emergency ActionMessages (EAMs) could be routed from NCA,through either the shore-based VLF stations, orthe airborne VLF relays, to the submarines. (To-day these airborne relays are known asTACAMO aircraft. TACAMO is an acronym forTake Charge And Move Out).

If there was a need for high data rateretargetting, or for two-way communications,designated submarines would be ordered viathe VLF radio link to prepare for high data rateor two-way communications. I n order to dothis, the submarines would erect a mast abovethe ocean surface to permit communicationthrough the high-orbit satellites mentionedearlier.

If there was a need for the submarine to re-port back to NCA, the submarine could beam amessage through the satellite using a 5-inchdish antenna which would be mounted on amast.

The probability of an adversary detecting orintercepting such transmissions would be verylow for the following reasons. The radio fre-quencies used by the satellites would be in theextremely high frequency (E H F) radio band andwould have a wavelength of order several mil-limeters. Because the wavelengths are sosmall, EHF signals would be collimated into an

extremely tight beam by the 5-inch dish an-tenna. Only receivers in the path of the beamcould receive the transmissions from the sub-marine. Since the dish antenna would also beh igh ly d i rec t iona l fo r rece iv ing s a t e l l i t esignals, it would be effectively impossible tojam incoming signals from the satellite.

The satellites could be survivable againstsatellite attacks. The high-orbit satellites couldbe put in five times geosynchronous orbits(almost halfway to the Moon) and would bevery difficuIt to attack, even using large spaceboosters.

Earth-launched interceptors would take 16to 18 hours to reach the satellites, During thisperiod, the satellites could be maneuveredwhile they are out of sight of Soviet ground-tracking stations, forcing the space boosters tomake course changes beyond their propuIsiveendurance. If there was an extended period ofconflict and the United States did not want tokeep repositioning these satellites, the ground-tracking stations could be destroyed and thesatellites could be repositioned for a finalt i me.

Submarine Navigation and MappingNeeded for High Missile Accuracy

In order to have high missile accuracy, themissile guidance system must have accurateinformation on the missile’s initial velocity,position, and orientation immediately prior tolaunch. This information can be obtained fromnavigation systems on the submarine and fromgravity maps of the submarine operating areas.These systems will be briefly described hereand will be discussed again in detail in thesection on missile accuracy.

The submarines would maintain accurate in-formation on their position using an advancedsubmarine inertial navigation system ESGM/SINS. They could also measure their velocityvery accurately using a VMS. This informationwould be fed to the missile guidance systemprior to launch so that errors in missile ac-curacy due to velocity and position uncertain-ties would be minimal.

Ch. 5—Small Submarine Basing of MX 175

ESCM/SINS could be reset by making navi-gational fixes on the GPS. If the satellites weredestroyed by enemy action, the navigationsystem could instead be updated using any of150 covert acoustic transponder fields.

The acoustic transponder fields would belayed by submarines while on normal patrols.Typically, such operations would take severalhours. After laying a transponder field, the sub-marine would determine transponder positionsusing the ESGM/SINS or the GPS. The tran-sponder field couId be turned on using an en-crypted acoustic signal that could be sent fromthe submarine or by a small, powered, under-water drone deployed by the submarine, Smallboats could later use an encrypted acousticsignal to command the transponders to releasetheir anchors and float to the surface forretrieval. In this way, the transponder fieldscould be constantly shifted if the need arose.

Orientational information for the missileguidance system would be obtained with theaid of gravity maps of submarine operatingareas. These maps would be generated usingsatelIites, surface ships, and possibly sub-marines to measure gravity anomalies near thesurface of the ocean and in space.

Missile Guidance Technologies

There are three sets of missile guidancetechnologies that could be used to maintainhigh accuracy from sea. These are:

1. pure inertial guidance,2. star-tracker-aided inertial guidance, and3, radio-aided inertial guidance.

The strengths and weaknesses of these sys-tems will be described in more detail in thesection on missile accuracy.

Pure inertial guidance would essentially besimilar to that of the land-based missile, withsome of the methods of performing missileguidance calculations modified for sea basing.

Star-tracker-aided inertial guidance wouldbe similar to that of the land-based system butwith the aid of a star tracker to help correct forposition, velocity and orientational guidance

errors that accumulate during missile flight.These corrections are done by sighting on astar and comparing the star’s measured posi-tion to that of its expected position. The Tri-dent I missile uses a star tracker and experi-ence with this missile has demonstrated thatthis technology is very reliable and effective asa means of obtaining high accuracy with sea-based missiles.

Radio-aided inertial guidance depends onradio beacons to correct for position, velocity,and orientational guidance errors that occur inmissile flight. These corrections are done bysighting on a system of radio beacons.

The system of radio beacons used by themissile could be either on satellites (the GPS)or on the surface of the Earth (such a systemhas been called a Ground Beacon System(CBS) or an Inverted Global Positioning System(IGPS)

If a submarine-based system used radio-aided inertial guidance as a means of main-taining high accuracy, a GPS guidance fixcould be taken by missiles launched anywherewithin the deployment area. I n the event ofoutage of the GPS, which could occur if thesatellites were attacked, the secondary land-based IGPS could be used to maintain themissiles’ accuracy. However, if the groundradio beacons are used, the missiles mighthave to be launched within 400 to 500 miles ofthe ground beacons in order to get goodenough l ine of s ight contact to maintainmissile accuracy.

The system of ground radio beacons couldbe deployed along the coast of the continentalUnited States and Alaska. There would be alarge number of such beacons and a largernumber of decoys to make it costly for theSoviets to attack the beacons.

If the GPS were destroyed, and a launchorder was issued, some submarines might notbe close enough to the continental UnitedStates to use the radio ground beacons. If timepermitted, NCA could direct the remainingsubmarines to redeploy to areas within thecoverage of the ground beacons or direct themto any of 150 presurveyed acoustic trans-


ponder sites in the open ocean. The subma- the missile does not have a star tracker). Ifrines could obtain extremely accurate mea- there was not enough time to redeploy tosurements of both position and velocity at acoustic transponder fields, missiles could bethese presurveyed sites. Missile accuracies launched with position and velocity informa-achieved from these transponder fields could tion from the ESGM/Sl NS and VMS submarinebe slightly degraded relative to that achievable systems. Under these conditions, missile ac-with the aid of the radio beacons assuming curacy wouId be degraded stiII further.that the missile was only inertialIy guided (i. e.,

VULNERABILITY

The vulnerability of the force of submarinesto Soviet countermeasures depends on the na-ture and capability of the weapons systemsthat would be deployed, the strategy of theirapplication, and the amount of resources thatmight be committed against the submarineforce.

Potential threats to the submarine force fallinto several broad categories:

1. barrage attack using nuclear weapons;2. large area searches, followed by barrage

attack;3. large area searches, followed by attacks

using surf ace ships or aircraft;4. nuclear explosion generated giant waves

(Van Dorn Effect); and5. trailing of the submarine force, followed

by simultaneous attacks on all the sub-marines.

A barrage attack is a pattern bombing at-tack, using nuclear weapons. In its simplestform, it is a random pattern bombing of oceanareas in which the Soviets suspect submarinesare operating.

A variation of the barrage attack is an areasearch followed by a barrage attack. If a nadversary possessed a search technology thatwas only able to locate submarines approx-imately over an extended period of time, thenonly those areas of ocean in which the approx-imate locations of submarines were knownwould be attacked. if the area in which thesubmarines are localized was small enough, itis possible that the barrage could result in thedestruction of the submarine force.

If an adversary possessed still better searchtechnologies, capable of localizing submarineswell enough to send out surface ships or planesto attack the submarines, it would be possibleto sink the entire force of submarines with con-ventional weapons or a very small number ofnuclear weapons.

Still another way that a force of submarinesmight be attacked is to detonate large nuclearweapons in sufficiently deep water to generategigantic waves, If the waves were large enoughand the water shallow enough the waves mighttumble the submarines, causing sufficientdamage to sink them or render them inoper-able. The phenomenon associated with thegeneration of such large waves with nuclearexplosions is called the Van Dorn Effect.

If an adversary’s ability to search large areasrapidly was inadequate for attacking the forceby limited barrage or with surface ships orplanes, he might instead choose to trail all thesubmarines. once a significant fraction of thesubmarines were under trail, they could thenbe attacked at a prearranged time, resulting inthe destruction of the submarines and theirmissiIes,

A barrage attack against the entire operatingarea would require more than 30,000 high-yieldnuclear weapons. If the high-yield warheads onthe missiles were replaced with a larger num-ber of smaller warheads (i.e., if the adversaryfractionated his force) the area of ocean thatcould be barraged would be no greater.

If the adversary instead chose to generategigantic waves by detonating large nuclear

Ch. 5—Small Submarine Basing 01 MX ● 177

weapons in deep ocean waters, the submarineswould not be damaged unless they were in cer-tain shallow water areas on the ContinentalShelf.

All other means of attacking the force ofsubmarines depend on an ability to detect andlocalize, or trail, submarines with varyingdegrees of success. Table 21 lists possibleobservable that in principle accompany thepresence or operation of a submarine, Sensingtechnologies that could potentially detect thepresence of the observable listed in table 21are Iisted in tables 22 and 23. These technol-ogies were examined as possible methods fordetecting and localizing a fleet of slowlypatrolling dispersed ballistic missile subma-rines. All these technologies were found to fallinto one of two broad categories: sensing tech-nologies that do not appear to offer any possi-bi l i ty of detect ing submarines effect ivelyenough to be able to threaten the submarineforce by area search or trailing; and sensingtechnologies that could be spoofed, confused,or rendered useless with inexpensive and easyto implement countermeasures.

Tactical and Strategic Applications ofAnt i submarine Technologies

it should be noted that many sensing tech-nologies of great use in tactical antisubmarineoperations are of Iittle use in the strategic role.

Table 21 .—Submarine Observable

Acoustic radiated soundAcoustic reflected soundHeat (infrared signatures, surface scars from snorkeling

submarines, hydrodynamic transport of reactor heat toocean surface)

Electromagnetic disturbancesOcean surface effects (Bernoulli hump, snorkel or

periscope wake, trailing wire wakes, microwavereflectivity of the ocean surface)

Hydrodynamic wake effects (salinity, temperature,conductivity, density, etc.)

Erosion and corrosion productsChemical EffluentsIrradiated elements in sea waterMagnetic field disturbancesOptical reflectivity (blue-green lasers)LuminescenceBiological disturbances of marine life

Table 22.—Acoustic Sensors forSubmarine Detection

Submarine sonar systemsActive sonarsPassive sonars

Conformal arraysHull-mounted arraysTowed arrays

Fixed array networksPassive (sonobuoys and arrays)

Surface ship sonarsActive

Standard ship sonarsSemiactive

High-power low-frequency transmitters in combinationwith long-towed arrays

PassiveHull-mounted arraysTowed arrays

Plane, ship, or helicopter deployed sonobuoysActiveSemiactive

Sound source plus receiversPassive

Helicopter sonarsDipping sonars


Table 23.—Nonacoustic Sensors forSubmarine Detection

Infrared systemsSnorkeling scarsReactor heat

Optical systemsVisual observations

Snorkles or mastsWakesNear surface effects

Blue-green laserSynthetic aperture and pulse compression radars

Surface roughnessSnorkels or antennasHydrodynamic wakesBernoulli hump

Sniffing devicesSnorkeling effluents

Magnetic anomaly detectorsPassive microwave radiometers

Surface roughnessHydrodynamic wakes

Electromagnetic detectorsTurbulence sensing systemsTrace element detectorsActivation product detectors




For example, an attack submarine that is mov-ing at high speed in order to position itself toattack a battlegroup or convoy may be makingtens or hundreds of times more noise than thatmade by a slow-moving balIistic missile sub-marine. The close proximity of the fast-movinghostile submarine and the large amounts ofnoise associated with highspeed operationsmakes the attack submarine susceptible todetection by the battlegroup. If the attack sub-marine is detected by a passive sonar and it isnot possible for the sonar operator to deter-mine the range of the submarine from the bat-tlegroup, a plane or helicopter equipped with amagnetic anomaly detector could be sent outalong the direction of the sonar contact tolocalize the submarine. The aggressive tacticsrequired of the attack submarine result in thesubmarine increasing its detectability whilesimuItaneously bringing itself within closerange of potent ia l adversar ies. This c ir-cumstance is completely different from that ofthe balIistic missiIe submarine.

Theory of Open Ocean Barrage

A barrage attack is a pattern bombing at-tack, using nuclear weapons, of ocean areas inwhich the Soviets suspect submarines to beoperating. I n the absence of information onthe locations of submarines, they would haveto barrage millions of square miles of sus-pected operating area. It is also possible thatthe Soviets would attempt to gain informationon the approximate whereabouts of submar-ines by using large area search techniques. If,for instance, each submarine in the forcecould be contacted and localized once a day,during the process of a large area search, thenthe approximate locations of the submarineswould be known within a 24-hour saiIing dis-tance of those contact points.

Figure 71 illustrates just such a circum-stance. This diagram illustrates the results of apostulated large area search in the Gulf ofAlaska that results in the observation and lo-calization of four submarines in a period of 2days. Upon observing a submarine, the searchaircraft notes its location and continues on itssearch pattern. The submarine is assumed to

be patrolling at 5 knots and may be moving inany direction from the point of contact. TheresuIt is that the submarine’s location is knownwith less and less certainty as the submarinecontinues its patrol. I n the diagram, the area ofuncertainty associated with the most recentlyobserved submarine is represented by a point.The smallest circle represents the area of un-certainty generated by a submarine observed10 hours earlier. The next larger circle il-lustrates the area of uncertainty of a subma-rine observed the day before and the largestcircIe represents the area of uncertainty asso-ciated with a submarine observed 2 daysbefore.

The ability to perform such large areasearches is based on considerably more thanjust the dedication of military assets, A tech-nology must exist that gives a sufficiently highsearch rate so that the mean time between sub-marine localizations is smalI relative to thetime needed for the submarine to generate anarea of uncertainty sufficiently large to be im-possible to barrage. For example, if a searchtechnology existed that, on the average, wasable to localize every submarine i n the forceevery 24 hours, then each submarine would onthe average be be localized within a circle ofradius 120 miles (see fig. 71 for an illustrationof the size of the l-day area of uncertaintygenerated by a submarine assumed to patrol atan average speed of advance of 5 knots). Thesubmarine would, on the average, be known tobe somewhere within a circle of area 45,000nmi 2. If the kill radius of a nuclear weapon isof order 5 nmi, then 500 to 600 weapons wouldbe required to assure that the submarine wasdestroyed.

Of equal importance to large area searchcapability is a low false alarm rate. If one falsealarm were generated per hundred thousandsquare miles searched, there would be 20 to 30additional targets that would have to be at-tacked that were not submarines (assuming thedeployment area was of order 2 million to 3million mi2). If the average submarine contactrate were stiII every 24 hours but there were, inaddition, 20 to 30 false alarms among the tar-gets, 10,000 to 15,000 nuclear weapons would


Figure 71 .—Number of Weapons Required to Destroy Submarines That Have BeenSighted Prior to a Preemptive Attack

Four submarines seen in two days

Speed - 5 knots

Kill radius per weapon - 3.5 nmiTime since last observation

Just observed -1 RV10 hr, 7,800 nmi2, 196 RVS

1 day, 45,000 nmi2, 1,130 RVS

2 days, 181,000 nmi2, 4,500 RVS


be required to cover the false alarms. Thus, thefalse alarm rate must be very small or it will bedifficult to narrow down the number of targetsto a manageable level.

Finally of significance in the barrage attackis the number of warheads available to theadversary for purposes of barrage. If thenumber of weapons grows to a large enoughnumber, it may be necessary to expand thesubmarine operating areas or create decoys toincrease the number of false targets observedin an area search. For conceptual purposes, anapproximate rule of thumb would be 20,000 to25,000 nuclear weapons are required to bar-rage a million square miles of deep oceanoperating area. I n shallow water, the kill radiusassociated with the underwater detonation ofa nuclear weapon is considerably smaller thanthat in deep water. There is between 70,000and 90,000 mi2 of Continental Shelf area (ex-

cluding the Continental Shelf of the Gulf ofMexico but including the shelf area of the Gulfof Alaska) available for submarine operations;a pattern bombing attack of these areas wouIdrequire between 25,000 and 30,000 nuclearweapons because of the smaller kilI radius.

Open Ocean Barrage With NoInformation About Submarine

Locations

The submarines would operate in an area ofocean sufficiently large so that a significantfraction of them could not be damaged by pat-tern bombing with nuclear weapons. The de-ployment areas near the east and west coastsof the United States and the Gulf of Alaska areshown in figure 72. The outer boundaries in thefigure are 1,000- and 1,500-nmi arcs from Narr-gansett Bay, R. I., Anchorage, Alaska, San


Figure 72.—Potential Deployment Area Given 1,000- and l,500mmi Operating Ranges

‘ - ” - ” “ - ” - ” - ’ -

SOURCE: Office of Technology Assessment.

Diego, Cal if., and the Miller Peninsula, Wash.The exact boundaries of this area could varysignificantly with choice of base siting andoperational procedures. The operational areawouId be of the order of 2 milIion to 31/2 mil-I ion miles.

In testimony given to Congress, Garwin andDrell have suggested that a strategic nuclearweapon detonated at the proper depth in deepwater might destroy a submarine at a distanceof 5 miles. According to this estimate, anunderwater nuclear detonation could destroysubmarines within an area of ocean of about75 mi2.

Garwin and Drell have also stated that thisdamage range could be considerably smaller ifthe submarine were operating at a shallowdepth. If an open ocean barrage were at-tempted, a large number of missile launcheswould be observed on early warning sensors.The submarines could be ordered via the VLFradio I ink to move to shallow depths where theeffects of underwater nuclear explosionswouId be much shorter range. If this move-

operatingrange

ment were to occur, the effectiveness of thebarrage would be substantially reduced rela-tive to the numbers quoted in the paragraphabove.

Assuming the Soviets could deliver as manyICBM warheads against MX-carrying subma-rines as they could against a land-based MXsystem (i. e., 2,300 warheads) and the subma-rine damage range is 5 nmi, submarines oper-ating with i n an area of 200,000 miIes of oceancould be destroyed or rendered inoperable bya nuclear barrage attack. This attack wouldresult in the loss of two to three submarinesand their missiles if the submarine operatingarea was Iimited to only 3 m i I I ion m i 2.

Open Ocean Barrage After Detection ofSnorkeling Submarines

If a sensing technology with a very highsearch rate and a very low false alarm ratewere available, it is conceivable that sub-marines could be contacted often enough thatthe entire operating area would not have to be

Ch. 5—Sma/l Submarine Basing of MX 181

barraged in order to sink the submarines.Assume a search technology capable of de-tecting submarines only when they are snor-keling. This device could be a passive sonardetecting the diesel engine tonals or an air-borne radar detecting a snorkel mast. If 50 sub-marines were uniformly dispersed within 3mill ion mi2 of ocean, one submarine could beexpected in every 60,000 nmi2.

Figure 73 illustrates the concept of a largearea search as it would apply to an aircraftsearching for snorkeling submarines, since thesonar ship would be unlikely to detect a sub-marine operating on batteries. The same dia-gram could apply to a sonar ship. Although thesonar ship would move more slowly than anaircraft, it is possible that its detection rangewouId be greater. The resuIt might be that boththe sonar ship and the aircraft could have thesame search rate. As illustrated, if the searchplatform passes within detection range of asubmarine, the submarine may not be snorkel-ing and wouId therefore not be detected.

Also worthy of note is that the submarinecould have the ability to counterdetect thesearch platform before the search platform isclose enough to detect the submarine. This dis-covery could occur if the search platform is afast-moving surface ship (that makes a lot ofnoise) or a radar plane (that emits a signal thatis detectable at a greater distance than thesignal reflected from the snorkel).

In order to develop a more quantitative pic-ture of the possible outcome of a determinedlarge area search effort, the following assump-tions are made about a large area search ef-fort:

1. a search technique is available that cansearch 14,000 nmi2 per hour, This methodmight be an aircraft that flies at 350 knotsand can observe snorkels at 20 nmi oneither side of its flight track or a longrange sonar system that is towed at 14knots and can detect snorkeling tonals at500 nm i in each direction;

2. submarines snorkel 10 percent of thetime;

Figure 73.—Large Area Search With TechnologyThat Can Only Detect Snorkeling Submarines


3. the probability of detecting a submarinewhen it is in range is 50 percent;

4. the number of false detections is in-f in i tesimal relat ive to the number ofvalid detections, even though extremelylarge regions of ocean are being searchedrapidly; and

5. there are 100 units searching the 3-million-nmi deployment area 24 hours per day365 days per year.

These assumptions lead to a detection rate ofone submarine every hour by the 100 searchingunits in the 3-milIion-nmi2 deployment area.

If the position of each of these submarineswas recorded, then 1 hour after being detecteda submarine couId be anywhere within a 5-mileradius of its original position. At 2 hours thedistance will have grown to 10 miles, at 3 hours15 miIes, and so on.

The Soviet Union could then pattern bombeach area determined by the patrol radius of apreviously sighted submarine. If nuclear weap-ons with kill radius of 5 miles were used, one


weapon would be needed to guarantee the de-struction of the submarine seen 1 hour earlier,four weapons would be needed for the oneseen 2 hours earlier, nine for the one seen 3hours earlier, sixteen for 4 hours, and so on. Todestroy 20 submarines, 2,870 weapons wouldbe needed, 5,525 would be needed to destroy25 submarines and 9,455 weapons would beneeded to destroy 30 submarines.

It should be noted that passive sonars wouldnot be able to localize submarines at suchgreat distances since fluctuations in soundtransmission in the ocean make measuring dis-tances impossible. Cross fixing with multipleunits would almost never occur because offluctuations in the acoustic transmission ofsound in the ocean. It would be a common cir-cumstance that the sound would reach one ofthe sonar units, but not the other.

If the units were aircraft searching withradar, they wouId have to make long transits inorder to remain on station. The aircraft wouldhave to transit from bases to the submarinedeployment areas, search the areas, transitback home, and be refueled and repaired forthe next transit out. In order to maintain oneaircraft on station continuously, three to sixaircraft would be needed. Some typical baseloss factors (i. e., the number of platformsneeded per platform continuously on station)are shown in table 24 for turboprop aircrafttransiting from Soviet bases to operating areas.

Finally, it is absolutely necessary that falsealarm rates be extremely low in spite of thefact that vast areas of ocean must be searchedat a very high rate. As will be illustrated in thediscussion to follow, even low or moderatefalse alarm rates would render the most effec-tive area search useless.

Searches With Technologies ThatObserve Non snorkeling Submarines

It is conceivable that a search could be per-formed using a technology that was able todetect the presence of a submarine whether ornot it is snorkeling. Such technologies might in-volve the use of active acoustic technologiesor magnetic anomaly detectors. The nature ofthese technologies is that they are short range.For purposes of discussion it will be arbitrarilyassumed that the detection range of thesetechnologies would be about 5 miles. Thisassumption should not be taken as a true esti-mate of capabilities since that would dependon the acoustic properties of ocean areas,magnetic storms, sensitivity of sensors, prop-erties of the target submarine, etc.

Since the sensors being discussed in this casedo not require the submarine to be snorkelingto be detected, all submarines within thedetection range of the sensor could be as-sumed to be detected. If it is assumed that anaircraft must travel more slowly for magnetic

Table 24.—Operational Factors Affecting Radar Searchof Submarine Deployment Areasa

Operating area or Soviet naval Distance Time on station Transitingnaval facility or air base (nmi) (hours)b time (hours)c

Norfolk Murmansk 4300 Not possible —Norfolk Cuba 870 6.6 4.1Charleston Murmansk 4600 Not possible —Charleston Cuba 610 7.2 2.9San Diego Petropavlosk 3600 0.2 16.9Seattle Petropavlosk 2800 2.1 13.2Northwest Cuba 1400 5.4 6.6

AtlanticNortheast Anadyr 2300 3.3 10.8

PacificaTlrne on station and Iratlsll assumes BEAR bomber configured for long-range Surveillance.b~lgh altitude transit followed by low altitude searchCTrarlSl! speed Of 425 knots Tran.slt times Include transit 10 search area and transl! back to base.

SOURCE. Off Ice of Technology Assessment

Ch. 5—Small Submarine Basing of MX . 183

detection (say 100 knots) then it would be ableto detect every submarine within a 5-mileradius of it as it moves along, This assumptionmeans the aircraft could search a 1,000 nmiarea each hour it is operating (assuming aprobability of detection of one when a sub-marine is encountered), I n order to achieve thesame detection rate that the aircraft in theearIier exampl e achieved, 7 p la t fo rmsequipped with magnetic anomaly detectorswould have to be substituted for each of theradar aircraft. Thus, it would require 700 air-craft on station continuously, which means afleet of 2,100 to 4,200 aircraft dedicated onlyto search of the deployment area. If weatherdid not interfere with the search and sub-marines did not take advantage of surveiIlancedata supplied through VLF channels to avoidsearch platforms, then 5,525 warheads mightbe needed in addition to these forces in orderto destroy half of the postulated force of 50submarines.

Active acoustic search might be substitutedfor passive. Since the range assumed is 5 miles,and ships might travel at only 20 knots, itwouId require 35 ships to replace every radar

plane in the first example (assuming a prob-ability of detection of one if a submarine iswithin the detection range)

A serious problem associated with activeacoustic search would be the problem of falsetargets. Simply stated, a false target is an un-derwater phenomenon that generates a sonarsignal similar to that of a submarine. The ex-istence of false targets generates an additionalcomplexity in the large area search problemthat can catastrophically degrade the effec-tiveness of the search effort:

1. nonsubmarine targets may be incorrectlyidentified and tracked as possible subma-rine targets, and

2. submarine targets may be incorrectlyidentified as nonsubmarine targets,

Figure 74 illustrates the circumstance of anactive acoustic search, The surface ship has asound transducer that emits sound that scat-ters off objects in the water. Unfortunately forthe searcher, sound not only bounces off thesubmarine, but it also bounces off temperatureboundaries in the water, bubbles, plankton,

Figure 74.—Sources of Reverberation That Limit the Capability ofHigh-Powered Active Sonars


184 MX Missile Basing

schools of fish, the ocean bottom, and theocean surface. 1 n particular, the sound thatreflects back and forth between the surfaceand the bottom of the ocean resuIts in an ex-tended and very intense echo. Since the sur-face area of the ocean floor and ocean surfaceare so great relative to the surface areapresented by a submarine target, the initialsound impuulse of the sonar returns Iike thedeafening echo from the walls of a cavernFrom the point of view of the sonar operator,each sound pulse is reflected by a myriad offalse targets and deafening echoes from the“walls” of the ocean, From this set of confuseddata, sound reflected from the hull of a subma-rine must be identified from sound reflectedfrom other “false targets” that could poten-tial I y be submarines.

Figure 75 is a chart of the number of whaletargets over 30 ft in length per 1,000 nmi thatcould potential Iy be mistaken for sonar targetsin the Western North Atlantic during themonth of September, Of all biological targetsin the ocean, whales are the most difficult todistinguish from submarines on sonar. Thesemarine animals resemble submarines in size,speed, acoustic characteristics, and certainmodes of behavior. When two or more whalesoccur together, as they frequently do, theyrepresent a very significant sonar target, Undernormal conditions whales swim at 4 to 8 knots,welI within the range of submarine patrolspeeds, and may fIee from manor naturaI”predator-s at speeds of more than 20 knots I naddition to returning submarine like sonarechoes, the power-fuItaiI flukes of whales pro-d u ce swimming sounds that resembIe thescrew ( i e , propelIer) noise of a submarine

Smaller fish can also have very large sonarcross sections because they have air-filledswim bladders that intensely reflect sound.When these fish collect into schools, they canpresent very convincing submarine-like sonarsignaIs.

If the submarine is moving, the reflectedsound from the hull will be slightly shifted infrequency relative to sound reflected from sta-tionary objects in the water. The frequencyshifted sound might be separable from other

sounds provided the submarine didn’t slowdown to reduce the the size of the frequencyshift. If the sonar platform speeded up in orderto get a higher search rate, the sound reflectedfrom the “walls” of the ocean would be shiftedin frequency. This would make it very difficultt. separate the frequency shifted “echo” fromreaI signals generated by moving targets.

If a submarine counterdetected an adver-sary performing an active acoustic search, thesubmarine could also turn toward or awayfrom the source in order to reduce the amountof reflected sound from the hull. The soundrefIection wouId be reduced because the inten-sity of sound reflected back toward the soundsource would be roughly proportional to thecross sectional area the submarine presents tothe source. Since the cross sectional areawouId be reduced by about a factor of 10, thesound refIected back to the acoustic searcherwouId also be reduced by a factor of 10 I n ad-d it ion, since the f rent or back of the submarinehas a more highly curved surface than the side,sound wilI be more diffusely reflected from thefront or back of the submarine then it wouldbe if it were reflected from the side. This sameprinciple of reducing detectability by causingrefIections to be diffuse is a I so of use in lower-ing the radar cross sections of aircraft.

Thus, there are many problems of both atechnical and operational nature that seriouslyhamper active acoustic technologies as ameans of searching out submarines.

Increased Range AcousticTechnologies

There are basically two ways that acousticsearch technologies might in principle bemade more efficient for long-range searchesfor submarines. One way would be to increasethe sensitivity of passive acoustics, the otherwouId be to increase the power of activeacoustics.

Unfortunately, the more power that activeacoustics puts into the water, the more soundreverberates through the ocean blinding theabiIity of the acoustic system to the smalIsignals from a submarine. Active acoustics can


F i g u r e — Potential Whale Sonar Targets (Western North Atlantic)

500

---6- No data available

I

II

300

200

,

- -

90° 80° 70°

+

60°

I

50°

SOURCE Oceanographic Off Ice, U S Navy


be very effective against submarines at shortrange, simply because the signal from a nearbysubmarine is so much more intense than back-ground signals. However, as the submarinemoves away from the active sonar, its intensitywill drop at least with the fourth power ofrange. Thus, if the submarine is twice as faraway, the signal from it wilI be 16 times weaker(24 = 16*). The background reflections from theocean surface and bottom will not change.Hence, it becomes more and more difficult todistinguish reflections from the hull of the sub-marine from the unwanted ocean reverbera-tions. Increasing the power of the sonar onlyincreases the unwanted reverberation alongwith the wanted signal, Thus, the nature ofsound propagation in the ocean presents a fun-damental limit to the increased capability ofactive acoustics.

Passive acoustics has similar barriers to in-creased performance. Passive acoustic sonarsmust discriminate the sound of a submarinefrom all the other sounds in the ocean. Thetotal radiated acoustic power of some foreignmodern submarines is measured in milliwatts.In a calm sea, the sound from one of these sub-marines at 100 yd would be equal to that ofocean wave and shipping background. No mat-ter how one improves the quality of detectorsand signal processing, the quietness of modernsubmarines and the noisiness of the ocean setfundamental barriers on the capability of long-range sonars against slowly patroning sub-marines,

* The fourth power law comes about as fol lows Sound em-

mitted from the sonar source and sound refIected from the sub-

marine on the average spread sphericaly at short range The In-

tensity of a sound wave that spreads sphericaIIy frorn a source

point WiII decrease as the square of the distance from that point

The intensity of found that ult imately arr ive back at the search

p l a t f o r m i S f i r s t d iminshed by a factor of d i s tance squared

before reaching the submarine, and then diminished by another

factor of distance squared after it iS reflected by the hull of the

submarine Thus, as the distance between the submarine and the the

search platform Inc reases, the ln tens i ty o f the s igna l that

uItimately arrives back at the search platform diminishes at least

as fast as the fourth power of that distance. If the effects of

sound absorption are also include, the intensity of the signal

r e c e i v e d f r o m t h e s u b m a r i n e w i l l d e c r e a s e d e v e n f a s t e r

fourth power law as the distance between submarine and search

platform increases

Increased Radar SearchUsing Satellites

Since large area search against snorkelingsubmarines is likely to be Iimited by the en-durance of aircraft and range of radars, it isconceivable that other more exotic platformscould be used for large area search. A high-resolution radar (i. e., synthetic aperture radar)has been flown on a satellite (Seasat-A had anL-band (25-cm wavelength) synthetic apertureradar) that has obtained a resolution of 25 mfrom altitudes of order 500 nmi. In principle,significantly higher resolutions are possible.Seasat was able to observe ships on the surfaceof the ocean with sufficient accuracy thatimage processing could resuIt in crude iden-tification of ship characteristics. Seasat was ,under certain conditions, also able to observethe hydrodynamic wakes of ships and the sur-face roughness of the ocean. Remarkable pic-tures of internal ocean waves, that impressthemselves through hydrodynamic coupling onthe roughness of the oceans surface, have beenobserved from Seasat radar reflectivity data. Itis reasonable to expect that higher resolutionradars can and will be built that could becapable of observing snorkeling submarines.

As an example of the surveillance capabilityof a low resolution synthetic aperture radarsystem, two photographs obtained through thecourtesy of M. L, Bryan of the Jet PropulsionLaboratory staff are presented in figure 76Photograph A was taken in the Bering Sea Testas part of the Fisheries Imaging Radar Surveillance Test Program. This photograph wa’taken using an airplane equipped with an Lband synthetic aperture radar. The small spoton the lower left portion of the photograph aresmalI japanese fishing boats operating a purseseiner (a large vertically suspended fishing netand the larger bright spots are mother shipsPhotograph B was taken on Seasat A orbi1291. It is the area off Newport Beach anOrange County in southern California. Thwhite streaks in the photograph are probablships. The bright and dark areas of ocean ardue to the changing roughness of the oceasurface and the angle of the radar return. Tl-multi ridged structures within some of th-


bright regions are surface manifestations ofinternal ocean waves that result in changes ofthe surface roughness and the radar reflec-tivity.

A high-resolution radar system searching avast and constantly shifting ocean surfacecould have a very high false alarm rate due torandom waves reflecting additional intensity,In addition, the capability of the radar wouldalso vary dramatically with the sea state (i. e.,size of waves and roughness of the ocean),since the ocean surface creates an intensebackground of reflected clutter that can bevery difficult to fiIter out.

The false target rate due to random wavemotion might be dramatically reduced by hav-ing the radar “repoint ” at the suspicioustarget. However, such a radar would requireconsiderably greater amounts of signal proc-essing in a technique already limited by signal

processing capabilities. Nevertheless, it is pru-dent to assume that signal processing andradars could be suff ic ient ly improved toobserve snorkeling submarines with a highdegree of confidence.

Figure 77 shows the ground track of a satel-Iilte that is at an altitude of 162 nmi and whoseorbit is inclined at 600 to the equator. Thisorbit is similar to that used by the SovietCosmos 954 radar satellite that entered theupper atmosphere over Canada on January 24,1978 (the actual orbital inclination of Cosmos954 was 65 O). Note from the figure that thesatellite coverage is predictably intermittent.[luring the 1.5-hour satellite period the groundtrack advances 22.50 on the Earth below andthe search pattern shifts to the west (note theorbits labeled one, two and three). After 16cycles the satellite arrives over the same pointon the Earth’s surface but it will only have

Figure 77.— Ground Track of Radar Search Satellite

60° inclination160-170 nmi altitude1.5-1.6 hr period



overfIown the deployment area on six or sevenorbits The satellite would spend about 4 to 5minutes over the deployment area during eachof the six to seven orbits. Thus, one satelIitespends no more than 25 to 35 minutes per dayover the deployment area. If two satelIites arein the same orbit but separated in phase by180 “, they would follow one another by 45minutes (i e , by half of the 90-minute orbitalperiod) .Thus, for six or seven orbits a day, sat-elIites would be over the deployment areaonce every 4S minutes Six to seven orbitstranslates to 9 hours per day (six orbits times1 5-hour orbital period) when satellites couldbe expected overhead every 45 minutes If twoother planes of orbits with two satellites eachare staggered so they wilI not overlap the firstplane of two satellites, then eight satelliteswould be required to cover the deploymentarea 8 minutes every 90 minutes. Covering thearea for 16 minutes every 90 minutes wouId re-quire 12 satellites and 32 minutes out of every90 minutes would require 24 satellites. Itwould thus appear that in order to cover thedeployment area 30 percent of the time, oforder 24 satelIites wouId be required.

If an eight-satellite constellation of radarsatellites was placed in orbit to cover thedeployment area, submarines could not snor-kel for periods of longer than 40 minutesbefore it would be necessary to secure snorkel-ing to hide from a satelIite. If 150 minutes ofsnorkeling were needed every day, eight satel-lites would force the submarines to snorkel forfour periods of 40 minutes each and 16 sat-elIites would drive the submarines to eight ornine periods of 18 minutes each. I f observationby a constellation of eight radar satellites hadto be avoided, the normal 150 minutes contin-uous snorkeling period wouId have to be ex-tended by 12 to 16 minutes due to the three tofour periods (of length 4 minutes each) thesatellites would be overhead. For 16 satellitesthe period could be extended to 180 minutesand for 32 satellites it could be extended tomore than 200 minutes. The submarines wouldtherefore have to be designed so they couldsnorkel for many successive short intervals.Current diesel-electric submarines may not becapable of this type of operation (modern sub-

marines may be able to interrupt snorkeling forperiods as short as the necessary 4-minuteperiods without serious losses in snorkeling ef-ficiency, but data on such procedures are notcurrently available) The power managementsystem of the small submarine might thereforehave to be configured so that the submarinescould snorkel efficiently for short periods oftime interrupted by stilI shorter periods of bat-tery operation. This approach would allowthem to avoid surveillance from a constella-tion of radar satelIites and would only mar-ginally affect the overall length of the snorkel-ing period.

Countermeasures to Radar SatellitesIf radar satelites were considered to be a

serious enough t h r-eat, Garwin and Drell havesuggested that the ocean couId be seeded w i t hradar refIecting objects that would be in-distinguishable from snorkels

If many false snorkel targets were deployedin waters near the continental United States, itcould make it easier for Soviet diesel-electricsubmarines to operate in U. S waters becauseU.S. naval forces could have as much d if fi-cuIty distinguishing faIse snorkels as wouId theradar satelIites. If the snorkels could not bedesigned to be distinguishable to U.S. navalforces, but not to space-based radars, such astrategic countermeasure could disrupt ourown tactical operations.

Another possibility would be jamming theradar satelIites from ground- or sea-based sta-tions. However, jamming could have interna-tional implications. Since the intermittentnature of the satellite orbits makes avoidanceof detection straightforward, neither of thesecountermeasures would likely be preferable tointermittent snorkeling.

War of AttritionAs mentioned in the introductory remarks to

this section, the strategy associated with agiven surveillance capability, coupled withavaiIabIemilitary resources, couId affect theoutcome of a preemptive attack on the forceof submarines. It is therefore possible that thesurveillance capability postulated in the sec-


tion on Open Ocean Barrage After Detection ofSnorkeling Submarines could be used to fight a“war of attrition” rather than attacking in onemassive barrage. A “war of attrition” approachto destroying the submarine force would sim-ply involve immediate attacks on the subma-rines whenever a snorkeling submarine isobserved. The outcome of this type of attackwould be considerably different from themethod discussed earlier of constant sur-veillance followed by a massive barrage at-tack. The time period over which the attackwouId take place wouId be days or weeks,rather than fractions of an hour Nevertheless,in order to assess the seriousness of such athreat, it is useful to get a sense of that timesca I e.

Let us assume that the Soviet Union is ableto keep 100 planes on station over a northwestAt lant ic operat ing area. This deploymentwould require the commitment of a fIeet ofbetween 300 and 600 planes constantly flyingthe 1,400 nmi transits to and from the operat-ing bases in Cuba. Assume for simplicity thatall the submarines are operating in a 3-million-mi operating area in the Northwest Atlantic.Then as estimated in the previous section, onesubmarine should be observed every hour ofoperation.

For purposes of discussion, assume thateach time a submarine is sighted it is attackedand sunk, and continental based U.S. forces donot react to this action at any point during theprocess. It could then be expected that approx-imately half the force of 50 submarines wouldbe destroyed in the first day. Since there nowwouId be half as many submarines distributedthroughout the deployment area, the rate atwhich submarines would be contacted and de-stroyed the next day would drop by two. ThiswouId then result in half the surviving sub-marines (about 12 submarines) being destroyedin the next day of operation. On the third day,the rate of contacts would drop again by twoand only six submarines would be left. Thiskind of circumstance is called a “war of attri-t ion” and was very successful against sub-marines in the North Atlantic during WorldWar I 1.

Another possibility is that a submarine isobserved once every hour but only ha If thetime the attack on the submarine results in itsdestruction. Then one fourth of the subma-rines are destroyed the first day (about 12 sub-marines), another 9 are destroyed during thesecond day’s operations, 7 the third day, 6 thefourth day, 4 the fifth day, etc. Thus, 5 days ofoperations resuIts in the destruction of 38 ofthe 50 submarines as compared to the previousexample where 43 submarines were destroyedin three days (it would take 7 days to destroy43 submarines using the assumptions in thecurrent example).

The “war of attrition” scenario would re-quire that the planes carry sufficient arma-ments to engage and sink submarines with ahigh probability. It would also require thatlarge relatively defenseless surveillance craftcouId continuously transit the 1 ,400-miIe routebetween Cuba and the submarine operatingareas, carrying out attacks on U. S, submarinesin airspace near the coast of the continentalUnited States, unopposed by American air andsea forces Another assumption is that sub-marines could not, and would not, defendthemselves with the aid of decoys or under-water to air missiles,

Van Dorn Effect

The Van Dorn Effect is the creation of ex-tremely high ocean waves over large areas of acontinental shelf by an appropriately placedmulti megaton nuclear detonation. The physi-cal basis for the Van Dorn Effect is as follows(see fig. 78). A wave created by an underwaterexplosion in uniform, deep water wilI divergeraidialIy untiI it moves into shallow water.when the water becomes shallow enough thewave energy is funneled into a smaller volume01

: water and the wave height grows in heightrelative to the height it wouId have had in deepwater. The shape of the Continental Shelf offthe eastern coast of the United States is suffi-ciently steep for an absolute increase in waveheight.

There is considerable uncertainty associatedwith the generation of Van Dorn waves. The


Figure 78.— Van Dorn Effect

Continental shelf

Nuclearexplosion


curvature , s teepness , and bot tom character-istics (i e , sand or rock) of the continentalslope could effect the size and formation ofwaves at different areas of the coast. The de-gree of underwater motion that submarines areIikely to be able to tolerate without losing theirabllity to launch missiles if also uncertain.

If a submarine were in sufficiently shallowwater, the water motion at the bottom of thesegiant waves would make it unlikely that thesubmarine wouId survive in good enough con-dition to be able to launch ballistic missiles Ifthe submarlne were operating off the Con-tinental Shelf, the water wouId always be deepenough that the Van Dorn Effect would not bea threat The Van Dorn Effect is therefore not aproblem for submarines operating off the Con-tinental Shelf

Because the nuclear explosions would haveto be generated in sufficiently deep water togenerate Van Dorn waves in the shallow water,there would be several hours’ warning beforethe arrival of these waves It any submarineswere operating in water too shallow to escapethe effect, and a Van Dorn attack were diag-nosed quickly, several hours would be avail-able for NCA to decide to launch missilesat risk.

Theory of Tra

It is conceivable that a c

Iing

etermined adver-sary couId review the method of continuoussurveillance followed by barrage and deter-mine that the Iikelihood of success is smallThe adversary might be particularly discour-aged after a review of the diversity, effective-ness, and cost of countermeasures relative tothat of his search and destroy effort It mighttherefore be concluded that an effort to con-tinuously trail the submarine force might bemore Iikely to meet with success.

To successfully trail a submarine, it isnecessary to have a device capable of sensingthe submarine with sufficient effectivenessthat some estimate of the position of the sub-marine relative to that of the trailer can bemaintained. It is also necessary that the devicebe difficult to spoof or jam and that it not besusceptible to simple countermeasures.

There are very few observable associatedwith the presence and operation of submarinesthat can be used to detect and track them. Themost effective and reliable of these, likemagnetic anomaly detection, tend to be veryshort range and cannot be operated too close-ly to a platform (like a surface ship or sub-


marine) that has its own magnetic signature.Longer range techniques (like sonar) tend to besubject to the constantly changing acousticproperties of the ocean. Acoustic trailingoperations are further complicated by thepossibility that the submarine could move intosound ducts, channels, and shadow zones, as ameans of suddenly “disappearing” from theview of the trailer. These ubiquitous soundducts, channels, and shadow zones are createdby in homogeneous ocean waters.

A final serious problem confronting thetrailer is the possibility the submarine willdeploy decoys, jammers, and/or spoofers tofurther complicate the problems of the trailer.Nevertheless, it is useful to examine some ofthe possibilities of trailing as a threat to theforce of smalI submarines.

The problem of trailing the submarine forcecan be broken into three major areas ofanaIysis:

1, initiating the trail,2. maintaining the trail, and3. destroying the submarine.

Once the submarine is within a few thousandyards, it is assumed that it can be destroyedwith a probability of one with conventionalmeans. This extraordinarily optimistic assump-tion presumes that the submarine under attacktakes no evasive actions and uses no devices toconfuse homing torpedoes or other devicesand that the weapon used against the sub-marine is 100-percent reliable.

According to these assumptions, the successor failure of the trailing operation would onlydepend on the ability to establish trail, and theability to maintain trail for a long enoughperiod of time that a significant fraction of thesubmarine force is on the average localized,Two extreme cases are useful to examine inorder to understand the significance of anability to establish and to maintain trail asseparate elements of the traiIing problem:

1, The probability of establishing trail is one,but the mean time a trail is held varies,

2. The probability of establishing a trail issmall, but the trail, once established, is

not broken for the remainder of the sub-marine’s at-sea period,

In case 1, for example, if the submarineswere always picked up successfuIly as theyegressed from port, then the average numberof submarines under trail wouId be equal tothe percentage of time each submarine washeld in trail during its patrol. For instance, ifthe submarines had a 60-day at-sea patrol andthe trail could be maintained for a period of 10clays, then one-sixth of the submarines wouldbe, on the average, under trail.

In case 2, the fraction of submarines suc-cessfully trailed is determined by the numberof submarines for which a traiI was success-fully initiated. In this case, if a trail were suc-cessfulIy established on egress from port one-sixth of the time, and maintained for the entireat-sea period, then one-sixth of the fleet wouldbe under trail at all times,

If one combines case one and two, andassumes that one-sixth of the submarines havetrails established on them as they egress fromport, and one-sixth of those submarines aremaintained on trail (because they are trailedon the average for 10 days out of 60), then one-thirty-sixth of the submarines (i. e., less than 3percent) can be expected to be under continu-ous trail. It is clear that both the ability tomaintain traiI and the ability to establish traiIare extremely important if there is to be anypossibility of maintaining contact with a sig-nIficant fraction of the force,

A more complete analysis of the trailingplroblem would include probabilities that trailsare established, broken, and reestablished. Inthe assessment that includes the possibilitythat a lost trail is reestablished, the possibleuse of muItiple sonars and magnetic anomalydetectors, surface ships using active andpassive sonar systems, etc., must also be in-cluded. In such a case, if the target submarineis recontacted by a search unit other than thetrailing unit (perhaps by a helicopter) the prob-ability that the search unit successfulIy handsthe contact back to the trailing unit (whichwouId have to be a ship or submarine i n orderto have endurance similar to the target) must


also be included in the analysis). Simulationsaccounting for such complexity have been per-formed. The models are technically complexand the results of the analysis are consistentwith conclusions drawn from insights gainedby examining cases 1 and 2. Since no new in-sights are gained with the additional com-plexity, and the models are mathematicallycomplex, these models will not be presented ordiscussed here.

Establishment of Trail at Port Egress

In order to establish a trail, it is necessary toknow the whereabouts of the submarine withina sufficiently small area of ocean that the sub-marine can be localized well enough to begintrailing operations. As discussed in other sec-tions, no technology has been identified thatappears to provide the ability to effectivelysearch large areas of ocean. Given this cir-cumstance, the trailer would have to seriouslyconsider attempting to trail at port egress,where submarines are initially localized, ifthere is to be any hope of success.

The trailer would have to use either anacoustic or nonacoustic sensing technology todetect and follow the submarine. This sensingtechnology would have to be both reliable anddifficult to counter. Since trailing operationswould have to be initiated at port egress,where substantial U.S. assets would be avail-able to help assure egress, the sensing tech-nology would also have to be unjammable andres istant to spoof ing f rom electronical lyequipped tugboats, submarines, or surfacecombatants that might aid in the egress.

The trailing of one submarine by anothercould be viewed as somewhat similar to thetrailing of a plane by a homing missile. Thehoming missile would either have to passivelysense some observable of the aircraft Iike heatfrom the engine, or actively illuminate the air-craft as with a radar. If the trailing missile isheat-seeking, the aircraft can disperse flareswhich the missile is unable to distinguish fromthe aircrafts engines. If the missile is radar-seeking, the aircraft can disperse chaff tocreate false radar targets to confuse the radar.

Another measure could simply be to jam theradar (which, depending on the radar, mightnot be so simple). Still another measure wouldbe for the aircraft to dispense a self-powereddecoy that would retransmit the radar signalfrom the trailing missile in a way that wouldmake the plane and the decoy indistinguish-able to the radar. Such a device (called theQuail) was deployed in limited numbers duringthe 1960’s on B-52s as an aid for use in confus-ing Soviet radars.

Such ideas have been applied in naval war-fare as well. During the Battle of the Atlantic,the Germans deployed an acoustic horning tor-pedo cal led the Zaunkoning. The Al l iedcountermeasures was to have convoy escortsstream noise emitting “Foxers” to create falsetargets and jam the acoustic homing torpedo’ssensing system.

If there were an attempt to trail a submarineusing passive sonar, for instance, trail could bebroken through the clever use of a “Foxer’’-likedevice. Such an operation could be done asfollows: A submarine being trailed may deploya small device that makes a sound similar tothe submarine. As the submarine proceeds for-ward, the device could be slowly played outbehind the submarine, making it appear to thetrailer that the submarine is moving more slow-Iy than it actually is. The trailer would thenhave to slow down in order to avoid risking acoll ision, resulting in an increased distancebetween the trailing and the trailed subma-rines. The device could also slowly increasethe intens i ty of the s imulated submar inesound, further convincing the trailer to in-crease his distance between him and his poten-tial adversary. At the appropriate time, the Iinecould then be cut or the trailing device shutoff. The trailer would only know that the sub-marine had disappeared from sonar contact.

A most likely technology of use to a trailerwould be an active or passive sonar. Activesonar at close range can be quite reliable(remember the distance to the fourth powersignal to noise relation). A problem with activesonar is that the trailer is more vulnerable toattack than the trailed, since the sonar isbroadcasting its own position.


Passive sonar is preferable to active sincethe trailer does not make himself quite sovulnerable to preemptive action or counter-maneuvers. However, if the submarine is quietenough, it will be exceedingly difficult to trailby passive means.

Figures 79 and 80 show another means ofmaking it difficult to establish trail against asubmarine using either active or passive sonar.The submarine (or accompanying tugboatsfrom the port) could deploy small torpedo-likedevices (similar, in principle, to the radar con-fusing Quails deployed by B-52s). These de-vices could be equipped with smalI taperecorders which simulate the sound of a sub-marine. EIectrical coiIs cou ld s imu latemagnetic and other signatures and a trans-ponder mounted on the device could simulatethe reflection of sound from the hull of a sub-marine. If the need arose, devices like thesecould not only be carried on submarines to aidin breaking trails, but they could be deployedin large numbers each time a submarine at-tempted egress from port. Devices deployedfrom the port could be preprogrammed tobehave like submarines and could regularly berecovered after each egress operation. Simple,

inexpensive, and recoverable devices could beconstructed using either battery or fuel celltechnology to simulate submarines egressingfrom port. The fuel cell device could be pro-gramed to behave Iike a submarine using an in-expensive microprocessor and would havegreat endurance. The device could be used todeceive trailers for days, if an operationalneed for such a capability arose. At some pre-programmed point it could turn around andcome back to port for recovery.

Sti l l another possible device that couldprove useful against a trailer using active sonarwould be a device similar to the German pil-Ienwerfer. The pillenwerfer was a device usedby German U-boats during World War Il. TheU-boats could eject this device during thecourse of an engagement and create a denseunderwater cloud of bubbles. Since soundwould be intensely reflected by the pil len-werfer bubble screen, active sonars could mis-take the cloud for a submarine or could notobserve the submarine maneuvering behindthe screen to escape.

Attempting to establish trail on a submarineegressing from a home port requires not only

Figure 79.—Active Acoustic Search for a Submarine That Has Dispensed DecoysWhich Simulate a Reflected Sonar Signal From a Submarine Hull



Figure 80.–Passive Acoustic Search for Submarine That Has Dispensed Decoys WhichSimulate the Sound of a Submarine

Noise from distantships, oil drilling,earthquakes, fish,rainstorms. ocean Noise reflected


“spoof proof” sensing devices with sufficientrange and reliability for “a trailing operation,but the technology must be difficult to jam.Jamming, while not as elegant as the methodof decoys, is at least as effective a means of“delousing” submarines as they egress fromport. This could be accomplished with smallsurface ships or preemplaced sound projec-tors . I f the t rai lers are us ing devices l ikemagnetic anomaly detectors, relatively mod-est-sized coil devices capable of distorting thelocal magnetic field could be emplaced in theegress region or towed by small ships. Thesewould, in effect, be magnetic jammers.

Still another tactic available for port egressoperations might be to use the 12-mile limit toforce the adversary to spread himself thin. Thesubmarines could proceed up or down thecoast well within territorial waters before pro-ceeding into the open ocean. Since the sub-marine would be in noisy shallow coastalwaters, it would be undetectable from outsidethe territorial limit. The adversary would vir-

tually have to commit thousands of ships to at-tempt to establish trail on port egress.

Finally, the logistics of establishing a picketin order to pick up egress ing submarinesshould not be neglected. Assets stationed out-side a port in order to try and pick up egressingsubmarines would have had to transit fromhome ports. This would mean that each shipwould have to spend a period of time coveringthe port access looking for egressing sub-marines, a period of time transiting back tohome ports for resupply and repair, and aperiod of time transiting back again to coverthe port. Enough ships and/or submarineswould have to be committed at all times to theport watch so that all the entrances, exits andcoast l ine which submarines could use foregress operations from the port would be con-tinuously covered. There must also be enoughexcess ships or submarines on station so thatall suspicious contacts can be prosecuted untilthey are determined to be false targets.


It should be clear that egress from port hassuch a rich diversity of countermeasures andtechnologies that it can effectively be con-sidered a nonexistent threat to any well-runsubmarine force.

Establishment of Trail Using Large AreaOpen Ocean Search

Since egress from port has such a variety ofoperational countermeasures and technol-ogies that favor the egressing submarine, anadversary may instead choose to combine alarge area search with trailing vessels at sea.

Again, for purposes of i l lust rat ion, i t i sassumed that 300 to 600 long-range aircraftequipped with radars that allow for a 14,000nmi2 per hour search rate transit from Cuba toa 3-million-nmi2 deployment area in the North-west Atlantic. This fleet of aircraft would belarge enough to maintain 100 aircraft on sta-tion, 24 hours per day. Between transit andsearch operations, these aircraft would con-sume more than 1.5 million gal of aviation fuelper day. As postulated earlier, such a searchmight produce a radar contact with 1 of the 50assumed submarines on the average of once anhour. This contact would occur when the sub-marine was snorkeling so the submarine wouldhave detected the radar signal and could bepresumed to recognize it had been sighted.

If the Soviets have, in addition, 1,000 shipsevenly distributed over the 3-mill ion-nmi 2

operating area, one ship will on the average beable to patrol a 3,000-nmi2 area of approx-imately 30-nmi radius. Assuming the ship is, onthe average, capable of arriving at the area ofcontact within 1 1/2 to 2 hours and the sub-marine has moved in a random direction at 10knots after being detected, the ship will haveto search an area of 700 to 1,2oO nmi2 by thetime it arrives in the vicinity of the aircraftradar contact. If the ship has sonar device witha 2- or 3-mile range and can search at 10 knots,it will be able to search about 40 to 60 nmi2

within the first hour of arrival at the locationwhere the submarine was first sighted. If thesubmarine is not found within the first hour ofsearch, it will have traveled another 10 nmi

from the point of sighting and would be some-where within an area of 2000 to 3,000 nmi2.

The probability of the ship picking up thesubmarine would be of order 0.03 to 0.08 andwould vary dramatically with how fast theships arrive at the point of aircraft sighting.Assuming that the probability of the ship es-tablishing trail is 0.08, then on the average, 2 ofthe 50 submarines would be picked up on traileach day of operation.

If the submarine were equipped with 10decoys, it could then attempt to break trail inthe following manner. If trail is established, asingle decoy could be released by the subma-rine, giving the trailer a one in two chance ofchoosing the correct target. If the correct tar-get is chosen, another decoy could be re-leased. Thus, by the time the submarine had re-leased its tenth decoy, the probability that trailis maintained would be about one in a thou-sand (210 = 1,024).

There are many variations on the openocean search followed by trailing. These varia-tions include the use of helicopters operatingfrom the on-station search ships and the use ofmultiple ships converging on sighting loca-tions. The assets that must be committed by anadversary, under optimistic assumptions ofgood weather and capable reliable sensors, isenormous relative to countermeasures. I n theabove case, the 50 submarines equipped with500 decoys are able to remain untrailed by anadversary who has committed a fleet of 300 to600 long-range surveillance aircraft, 1,000 sur-face ships, and sensors that surpass the per-formance capabilities of what is likely to beachievable.

As is indicated throughout the discussion onvuInerability, opportunities for obtaininginformation on the location of snorkeling sub-marines are far greater because of the in-creased noise output associated with snorkel-ing and the fact that a snorkel mast is exposedabove the ocean’s surface. Detailed analysisindicates that long-range passive detection ofmodern snorkeling submarines would not be athreat to the survivability of the force. Analysisindicates that nonacoustic search techniques


that might be able to detect snorkels will alsonot seriously affect the survivability of a fleetof diesel-electric ballistic missile submarinesdeployed within 1,000 to 1,500 nmi from thecontinental United States and Alaska.

Nevertheless, as remote sensing improvesand satellite surveillance becomes more com-plete, it is possible that concern about theneed to snorkel could arise. It is therefore ofinterest to describe some features of moderndiesel-electric propulsion systems and com-pare them to another proven propulsion tech-nology — nuclear propulsion.

Diesel-Electric Propulsion Technology

The diesel-electric propulsion system in theGerman-type 2000 powerplant is an example ofproven capabilities in modern nonnuclear sub-marines (see fig. 81). The submarine is designedto snorkel using four 1,400 RPM high-speeddiesel-driven generators simultaneously. Whenconfigured as an attack boat, it will snorkelless than 90 minutes out of 24 hours (assumingit snorkels with a 6-knot speed of advance andpatrols on batteries at 5 knots). If the sub-marine were configured as a strategic weaponsubmarine instead, additional power would be

Figure 81 .—German Type 2000 Submarine

I

— . Upper deck

2370 Metric Tons Displacement (Surf)


● X M i s s i l e B a s i n g

consumed due to increased hydrodynamicdrag on the missile fairings and added loaddue to the strategic weapon system and themissiles. The snorkeling period with these addi-tional loads would be about 2‘A hours per day(i.e., the submarine would snorkel about 10percent of the time). The submarine carries 960batteries which are energy-managed by a mi-croprocessor. The propulsion motor has a max-imum output of 7,500 kW and is double massisolated from the hull for silencing. The motoris air coupled to the shaft (for silencing) andthe shaft drives a seven-blade skewback pro-peller. When configured as an attack sub-marine, this boat has a top speed close to 25knots (which can be maintained for about 1hour).

When operating on batteries, any moderndiesel-electric submarine will, for all practicalpurposes, be close to acoustically undetect-able by passive means. Thus, the diesel-electrictechnology demonstrated in the Type 2000would easily fall within the assumed capabil-ities of the vulnerability discussion presentedearlier.

Nuclear Electric Propulsion

Small submarines that use nuclear propul-sion might have survivability superior to thosepowered by diesel-electric systems. * However,this would depend on the nature of any unfore-seen future threat that might emerge and istherefore dissicult to analyze.

It is generally acknowledged that nuclear-powered submarines are noisier than diesel-electric submarines. If the acoustic outputs ofnuclear-propelled strategic submarines werelarge enough to result in a threat to their sur-vivability (and they are not), proven technol-

‘It IS hard to say that a coastally deployed, small strategic submarine would be more or less survivable if it were nuclearpowered since its survivability would not depend on an ability tomaintain high speeds for extended periods of time, as might bethe case with attack submarines In addition, since the coastallydeployed submarines would always be relatively near the con-tinental United States, they would not have long transits to andfrom patrol areas In any case, the survivability of either diesel-electric and the nuclear-powered units would be so high that thechoice of propulsion system need not be of serious concern

ogy exists that would permit them to be equal-ly quiet.

Since the coastally deployed strategic sub-marine has modest power requirements rela-tive to those needed by longer range faster andmore versatile submarines, it is possible to usean inexpensive self-regulating TRIG A-type nu-clear reactor as a power source alternative todiesel-electric propulsion. The power systemwould employ fully developed reactor tech-nology used in conjunction with standard hard-ware and electronic components. Because ofthe self-regulating features of this type of reac-tor (and, in fact, any small low enrichmentreactor), the safety and control systems on thereactor would be very simple. The reactorwouId be natural circulation and conversion toelectricity could be accomplished using ther-moelectric modules (about 4 to 6 percent con-version efficiency is within proven technol-ogy). The reactor, with its shielding, wouldweigh about 100 tons. Since the reactor wouldgenerate electricity without the use of movingparts (neither generators or pumps), the sub-marine would be as quiet as an electric-pow-ered submarine and would never have tosnorkel.

The submarine could carry 550 tons of bat-teries as does the Type 2000 submarine since itwould need extra propulsion power on occa-sion. It would therefore have high-speed capa-bility similar to the Type 2000 until the bat-teries were drawn down. Quick rechargingwould be done with the aid of diesel-drivengenerators. Since quick recharging would rare-ly be required under normal operating cir-cumstances, the submarine would carry onlybetween 50 and 100 tons of diesel fuel.

The weight budget of the Type 2000 subma-rine indicates that a small submarine design ofthis type is well within proven technology. TheType 2000 carries close to 300 tons of fuel andthe modified TRIGA reactor weighs about 100tons. Care would have to be taken in the sub-marine design to account for differences inweight distribution dictated by a single largecomponent Iike a reactor.

A specific system design and the fabricationof a prototype would be required before a


reactor unit could be brought into service. Ifreactors were then produced at a rate of atleast six units per year, it would cost less than$20 million (1981 dollars) per unit. This figurewouId add only a marginal cost to the sub-marine.

If a decision were to be made to deploy MXmissiles on small submarines, such a propul-sion system would clearly be a competitor withdiesel-electric propulsion, both in terms of sur-vivability and cost. This deployment wouldhave to be considered by any design grouptasked with the problem of designing an MX-carrying system of small submarines.

Concluding Remarks on theVulnerability of Submarines

Antisubmarine warfare techniques andmethods is an area of high sensitivity due to

concerns about security. For this reason, thenumbers used in this section in conjunctionwith specific search technologies should in noway be construed as indicating the state of theart with regard to the sensing technologies dis-cussed. What this discussion has sought to dois provide the reader with a sense of the rich-ness, diversity, and complexity that accom-panies both submarine technologies and oper-ations. It should also be noted that all tech-nologies that could in principle or in practicebe used as a means to find submarines havenot been discussed. However, the conclusionsthat can be drawn about the survivability ofstrategic submarines from the present discus-sion in fact vastly overstate the vulnerabilityof these systems.

FACTORS AFFECTING THE ACCURACY OFLAND- AND SEA-BASED MISSILES

In this section, some of the factors that playa role in determining the accuracy of land- andsea-based ballistic missiles are presented inorder to establish a context for discussion inthe sections that follow.

A ballistic missile is a device that is ac-celerated to a velocity sufficient to reach atarget or set of targets without further propul-sion. Intercontinental range ballistic missiles(missi les with a range of order 6,000 miles)generally undergo powered flight for a periodof 5 to 10 minutes. Once powered flight iscomplete, the missile’s upper stage and reentryvehicles float toward a target, or a set oftargets, under the influence of gravity in thenear vacuum of space. In the final portion ofthe flight, the reentry vehicles enter the upperatmosphere and are subjected to very strongaerodynamic forces before finally arriving attargets.

During the initial stages of powered flight,guidance errors can be introduced by uncer-tainties in the missile’s velocity, position, and

orientation. The effects of these uncertaintiescan be understood if a comparison is drawnbetween the different stages of the ballisticmissile’s fIight with those of the fIight of a rocklaunched by a catapult. The powered phase ofthe ballistic missile’s flight can be thought ofas similar to the action of catapuIting the rockand the unpowered phase can be thought of asthe motion of a body in a gravitational field. Inthe unpowered phase, the motion of the bodyis entirely determined by the force of gravity.

Since the phase of powered flight is similarto that of the catapulting of a rock, if themissile is almost on course after the engineshave burned out, but the magnitude of its ve-locity is sl ightly in error, it wil l fall short orlong of the target (see fig. 82). If the missilevelocity is correct but the missi le is sl ightlymisaligned from its intended direction, it willalso miss the target. In addition, even if themissile is properly alined and has the correctspeed, if its launch point is moved with respectto the target, the missile will again miss itstarget.


Figure 82.— Factors Affecting the Accuracy of aBallistic Missile


The effects of uncertainties in the gravita-tional field also influence the missi le’s ac-curacy in the early stages of powered flight.When the missi le is initially launched, theforces that determine the motion of the missileare due to the thrust of the rocket’s enginesand the gravitational field of the Earth (aero-

dynamic forces are neglected here for sim-plicity). If the gravitational field is not knownin detail, the missile will end up, after launch,with a slightly different direction and velocitythan originally intended. Since this change oc-curs ear ly in the miss i le’s f l ight, a s l ightmisalignment in direction, or uncertainty invelocity, accumulates into a much largertarget miss as the missi le floats for greatdistances along its trajectory. As will be ex-plained later in this section, these velocity anddirection errors can be introduced due to lackof knowledge of the Earth’s gravitational field,as well as due to imperfections in differentelements of the missile system. If unaccountedfor, these errors can accumulate into signifi-cant miss distances at the target.

After the missile’s engines are turned off, itsmotion is determined by the gravitional fieldof the Earth. If the gravitational field is dif-ferent from that which is expected, the reentryvehicle will not follow the trajectory that hasbeen planned for it. For this reason, the missileguidance system must have data on the natureof variations of the Earth’s gravitational fieldalong the trajectory to the target.

Still later in the missile’s flight, the reentryvehicle enters the upper atmosphere andbegins to decelerate violently (this processusually begins at about 100,000 ft for a war-head flown at intercontinental ranges), In thisstage of flight, wind and rain can have an ef-fect on the reentry, as well as uneven ablation,body wobble, or misalinement. Errors that oc-cur in guidance during this stage of ballisticmissile flight are called “reentry errors. ”

Missi le accuracy is generally defined interms of the circle of equal probability (alsocalled the circle error probable) or CEP. TheCEP is the radius of a circle that is drawnaround the target in which, on the average,half of the reentry vehicles fired at the targetfall. There are two geometric contributions tothe CEP. The first is called the cross range ortrack error. This error is a measure of the missdistance perpendicular to the direction of themissile’s motion at the target. The second geo-metric contribution to the CEP is the downrange or range error, that is the miss distance


along the direction of the missile’s motion atthe target.

Table 25 shows the different contributionsto target miss for a missile which depends onpure inertial guidance at a range of 5,500 nmi.This table gives some indication of the impor-tance of initial errors in position velocity, andalignment in determining the missile’s CE P.Each of these error components contributes tothe down range and cross range errors as thesquare root of the sum of the squares (see fig.83). The CEP is then 0.59 times the sum of thedown range and cross range errors.

The major factors that contribute to the ac-curacy performance of any inertially guidedintercontinental range ball istic missi le (mis-siIes of nominal range of 6,000 nmi) can bebroken into the following categories:

1.

2.

3.

4.

uncertainties in the initial position, veloc-ity, and orientation of the missile at launch,boost phase guidance errors due to inertialsensing errors, and inertial computationalerrors,thrust termination errors at the end of theboost phase,velocity errors imparted to reentry vehiclesduring deployment by bus,

5.6.

7.

gravity anomaly errors,uncertainties in the position of targets (tar-geting errors), andatmospheric reentry errors.

Although the magnitude and importance ofeach of these factors in determining missile ac-curacy will vary (with missile design, missilerange, weather conditions over the target area,and the quality of gravitational data over theflight trajectory of the missile), all but two ofthese factors are in principle the same for bothland- and sea-based missiles.

Factors 1 and 5 account for most of thedifference in accuracy of land- and sea-basedsystems.

Since sea-based missiles are constantly inmotion, the missile must be provided with ac-curate information on its position, velocity,and or ientat ion. Th is necess i ty requi res anavigation system capable of providing infor-mation to the missile before it is launched. Thequality of this navigational data will affect theperformance of the missile.

The quality of gravitational data near thelaunch points of land- and sea-based missilesmay differ. If this is the case, this too will af-fect the accuracy performance of the missile.

Table 25.—Miss Sensitivities to Initial Errors for ICBM Trajectories

Error Component Miss SensitivitiesUnits Down Range Cross Range

Initial Down range m/m 1 0.0Posit ion Cross range m/m 0.1 0.7Error Vertical m/m 5.4 1.3

Initial Down range m/(cm/see) 40 9Velocity Cross range m/(cm/see) 2 10Error Vertical m/(cm/see) 22 6

Initial Level m/arcsec 46 21Alignment Azimuth m/arcsec 6 24

“These values apply to a 5500 nmi minimum energy trajectory CEP = .59 (Down range error + cross range error),

SOURCE. “Guidance System Application of MX Basing Alternatives” by Major G B Green/SAMSO and L N Jenks/TRW

83-477 0 - 81 - 14


Figure 83.—Down Range and Cross Range Errors of a BallisticReentry Vechile at a Target


ACCURACY OF SMALL SUBMARINE BASED MX

The object of having a missile with great ac-curacy is to have the ability to place warheadssufficiently close to very hard military targetsso that there will be a high probability of de-stroying them. The abil ity to do this wil l ingeneral depend on the nature and the qualityof the guidance technology used by a missilesystem and the range of that missile from itstargets.

The MX, as designed, is a purely inertialguided missile. In the following presentationthe accuracy of a sea-based MX that uses pure-ly inertial guidance will be discussed next, andthe accuracy of a sea-based MX that uses iner-tial guidance in conjunction with radio bea-cons will be discussed last.

Figure 84 is a graph of the CEP accuracymultiplier for a sea-based MX with pure inertia Iguidance. A CEP accuracy multiplier of 1.0 onthe graph means that the expected CEP of themissile at that range from target will be equalto the engineering-design requirements for theland-based MX. A CEP multiplier of 1.5 meansthat the CE P at that range will be 1.5 times that

Figure 84.—Accuracy of Inertially Guided Sea-BasedMissile at Different Ranges From Targets

Land-basedMX accuracymultiplier

0 1 2 3 4 5 6

Missile range (thousands of nmi)

SOURCE: U.S. Navy.

of the design requirements of the land-basedMX, and so on. At present, it appears likely thatthe land-based MX will have a smaller CEPthan that set for its design requirements, so aCEP multiplier of 1.0 does not necessarilymean accuracy equal to a land-based MX. Thegraph assumes that the submarine’s position isknown within a few meters and that it woulduse a velocity measuring sonar to measure its


velocity. None of the above assumptions pre-sent any operational problems for the sub-marine fleet (for reasons that will be discussedlater) and so this graph can be considered agood operational representation of achievableaccuracies at different ranges from targets.

In order to i l lustrate the significance ofrange from target effects for the small sub-marine-based MX missile, table 26 Iists a num-ber of cities in the Soviet Union in regions thatalso may have targets of military interest. Thenumber in the upper part of each of the boxesin the table is the range from one of the threesubmarine deployment areas to targets withinthe regions surrounding these cities. In thelower part of each box the expected hard tar-get kill capability of a sea-based MX is com-pared to that of the hard target kill require-ments for the land-based missile. It should bekept in mind that the accuracy requirementsset for the land-based MX result in very largesingle shot kill probabilities against targets ofgreat hardness. In fact, the single shot ki l lprobabilities used to compile table 26 are suf-ficiently large that differences described as“slightly better, ” “comparable,” and “slightlyworse” r-nay not be of military significance (seeClassified Annex for numerical details).

If targets in the region around Novosibirskwere to be attacked, warheads would have to

travel roughly 3,700 nmi to reach their targets.The graph in figure 83 indicates that for thatrange, warheads fired from the Gulf of Alaskacould have an expected accuracy at the targetSIightly better than the design requirements setfor the land-based MX. Missiles fired from theNortheast Pacific deployment area would haveslightly worse accuracy than that of the land-based design requirements and missiles firedfrom the Northwest Atlantic deployment areawould have still worse accuracy than thosefrom the Pacific area.

The significance of a slightly improved ordegraded hard target kill capability becomessti l l less significant for hard targets whichmerit attacks with more than one warhead. If,for instance, a single warhead fired from onesubmarine operational area had a probabilityof 0.95 of destroying a particular hard targetand a second warhead fired from a differentsubmarine operational area had a 0.85 kil lprobably against the same target, a 2-on-l at-tack would still have a greater than 0.99 prob-ability of destroying the target being attacked.This means that cross targeting could be per-formed from different operational areas withconsiderable fIexibility.

This point is applicable even for targets inareas that are extremely far from al I of the sub-marine operating areas. Even though these tar-

Table 26.—Comparison of Hard Target Kill Capabilities of Sea-Based MX”With Design Requirements of the Land-Based MX

Relative hard target kill capability

Range to target from launch area Gulf of Alaska Northwest Atlantic Northeast PacificMoscow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Semipalatinsk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Vladivostok. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Novosibirsk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Minsk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Irkutsk. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Tashkent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Tyuratam. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4,200Comparable

4,000Slightly better





4,600Comparable

4,500Comparable


5,200Slightly worse

5,800Worse4,800

Slightly worse3,600

Slightly better5,200

Slightly worse5,600

Worse4,900

Worse

4,500Comparable

4,700Slightly worse


4,400Comparable

4,600Comparable


5,500Worse5,200Worse

a Numerical values available in the Classfied Annex



gets are at very great distances from all thesubmarine operating areas, and accuracy de-grades with distance from target, such targetswill still be subject to successful attacks fromsea-based missiles in the late 1980’s and early1 990’s.

The most extreme test of the system capa-bility shown on table 26 are targets in theregion surrounding Tashkent, in the extremesouthern region of the Soviet Union (Tashkentis about 200 miles from the Soviet Union’sborder with Afghanistan). Single warheadsfired from the Gulf of Alaska would have totravel about 4,600 nmi to targets in that regionand would have single shot kill probabilitiescomparable to the design requirements set forthe land-based MX. Missi les fired from theother two operating areas would have to tra-verse much greater distances (about 5,600 and5,500 nmi). The probability of destroying hardtargets in this region with a 2-on-1 attack usingmissiles from any combination of submarineoperating areas would differ by only a few per-cent. Thus, even in the extreme case of verydistant hard targets, 2-on-1 targeting wouldresult in an almost indistinguishable differencein capability to destroy very hard targets of im-portance.

If the targets were to be made still harder inan attempt to increase thei r surv ivabi l i tyagainst sea-based warheads with the yield ac-curacy combinations used to construct table26, it might be possible to gain several percentmore survivability against 2-on-1 attacks. Thesmall gains introduced by such a program,would be enormously costly and could bewiped out by additional possible improve-ments in accuracy.

Table 26 assumes that al l miss i les f i redagainst targets work, that is, it is compiledunder the assumption of 100-percent missilereliabil ity. If missi le reliabil ity is not betterthan the single shot kill probabilities, missilereliability wiII be more important a determi-nant of the hard target kill capability than ac-curacy. In the opinion of OTA, single shot killprobabilities from sea-based missiles could beso high by the 1990’s, that missile reliability,

not accuracy, wil l be the dominant factordetermining hard target kill capabilities.

The guidance technology assumed in table26 assumes minimal changes to the MX missileguidance system. The MX computation tech-niques used by the guidance system wouldhave to be optimized for sea basing ratherthan land basing and high frequency gravita-tional data of the quality expected to beavailable in the late 1980’s or early 1990’swould have to be known within a 200-nmiradius of the launch point. In addition, thedata summarized in table 26 assumes that thesubmarine would know its position to severalmeters and would use a velocity measuringsonar to update its velocity. Analysis per-formed by OTA indicates that the use ofvelocity measuring sonars does not introduceeither operational or vulnerability problemsfor the MX-carrying submarines. However, ifthe GPS were destroyed, the satellites wouldnot be avaiIable for position update im-mediately prior to missile launch. If the sub-marine did not take satellite position updateseveral hours prior to launch, knowledge of itsposition would be sufficiently degraded thatthe accuracy curve presented in figure 84could not be achieved against distant targets.This potent ial problem is , however, easi lysolved by proper force management.

If antisatell ite boosters or launches weredetected from American early warning sensors,the submarines could be informed over VLFchannels that an attack on the satelIite naviga-tion system could be in progress. In responseto this, the submarines would immediately pro-ceed to update their navigational systems inthe hours before the intercepts. While perform-ing the satell ite fix the submarines couldsimultaneously issue a “ready” signal to NCAvia the Deep Space Millimeter Wave SatelliteSystem. Since the submarines would be underorders to avoid all shipping at all times, itwould be extremely unlikely that a submarinecould not take a fix within the time periodbefore loss of the satellites.

In the unlikely event that one or two sub-marines were unable to take a fix before hostil-


ities began, they couId immediately proceed to

t h e n e a r e s t a c o u s t i c t r a n s p o n d e r f i e l d . T h i sw o u l d t a k e t h e s u b m a r i n e b e t w e e n 2 t o 3hours. If a launch order were given during thisperiod of time, submarines with sufficientlyaccurate guidance data couId be in a positionto launch without risk to the ship. Any sub-marine that had not reported a “ready” signal

tion. This could be done using VLF channels ifit only required reassignment of a prepackagedoption or it could require the high data ratesatellite I ink if ad hoc targets which are notlisted on the National Target List are to be at-tacked. This force management procedurecould therefore guarantee that the submarineforce could strike targets on short notice with

could immediately have its target package re- very higlassigned to one of the other submarines on sta-

ACCURACY OF STAR-TRACKER-AIDED

accuracy.

NERTIALLY GUIDED MX

Heretofore only the accuracy that is likelyto be attainable using purely inertial measure-ments as a means of guiding the missile is con-sidered. We now consider the additional ac-curacy that could be attainable if the inertialguidance system is updated using some formof external reference. First the use of startrackers is discussed, and then the use of radiobeacons, as means of updating the missile’s in-ertial guidance system in order to obtainhigher accuracy at greater ranges.

It is possible to mount a device on the mis-sile guidance platform that will allow it to takea fix on a star after it leaves the atmosphere.This technique is currently being used on thenew TRIDENT I missile and would be a mores igni f icant modif icat ion to the MX miss i leguidance system than that assumed in con-structing table 26, Such a modification coulddelay the deployment of the missile by a yearand cost several hundred milIion dolIars. How-ever, as wiII be discussed in the section onschedule, the submarines design and construc-tion schedule shouId pace the missile develop-ment. Delays in the research and developmentof the missile wouId therefore not be likely toaffect the date that the first missiles could beput to sea.

The broad band in figure 85 shows a conserv-ative estimate of the band of possible ac-curacies versus range for an MX-Iike missilewhich has been fitted with a star tracker, As infigure 84 the accuracy multiplier is definedwith respect to the engineering design require-

ments of the land-based MX missile. The upperpart of the band is the accuracy versus rangecurve that is very likely to be achieved in thelate 1980’s or early 1990’s. The three verticalarrows define the distances to Tashkent fromthe Gulf of Alaska, Northeast Pacific, andNorthwest Atlantic deployment areas. As canbe seen from the graph, it is very likely that alltargets in the Soviet Union could be attackedin the late 1980’s or early 1990’s from allsubmarine operating areas with accuraciesmarginally better or worse than that of theengineering design requirements of the land-based MX. The lower part of the band repre-sents a conservative estimate of what is possi-ble in the late 1980’s or early 1990’s if the ad-vanced MX inertial measurement unit is usedin conjunction with a star tracker. If this levelof performance is reached, all targets could becovered from all deployment areas with CEPsat least as good as the engineering design re-quirements of the land-based MX,

For purposes of reference to the earlier dis-cussion, the dashed line plotted in figure 85shows the accuracy multiplier versus range foran MX missile guided without the aid of a startracker. The hard target kill probabilities usedto construct table 26 and discussed earlier inthis section are derived from this curve. Sincethe addition of a star tracker to the inertialguidance package helps reduce certain range-dependent guidance errors during the earlystages of flight, the star tracker aided inertiallyguided missile displays a weaker degradation


Figure

Land-baseMX CEPmultiplier

85.—Accuracy of Star-Tracker=Enhanced Sea= Based Missile as aFunction of Range From Target

I

d

2000 4000 6000

Range (nmi)

SOURCE: U.S. Navy

of accuracy with range relative to that of thepurely inertial guided MX.

It should be noted that the star tracker ac-curacy versus range curve shown in figure 85 isderived on the basis of assumptions about theavailability and capability of certain technolo-gies relevant to guidance, quality of naviga-tional data at the time of launch, and knowl-edge of geophysical data around the launchpoint and along the missiles trajectory. Theassumptions are as follows:

position and velocity data at time of launch.Accurate data at time of launch could beobtained with the aid of: acoustic trans-ponders, velocity measuring sonars, and theGlobal Positioning System.2. Introduction of gravity gradiometers onsubmarines and/or quality high frequencygravity data within 200 nmi of the launchpoint. It is expected that these technologiesand data will be available in the period ofthe late 1980’s to early 1990’s.

1. An Improved Submarine Inertia! Naviga-tion System (SINS) and/or accurate initial

DEGRADATION IN ACCURACY AFTER ASUBMARINE NAVIGATION FIX

Because a star tracker enhanced, inertial It is expected that submarine inertial naviga-guided missile is able to obtain navigational in- tion systems will be considerably improvedformation by sighting on stars during its flight, even relative to their currently impressiveits accuracy at range is not as sensitive to navi- capabilities. Improvements in inertial guid-gational uncertainties introduced by the con- ance technologies, gravitationaly mapping andtinuous motion of its launch platform, as is the the use of star trackers on missiles is expectedcase with a purely inertial guided missile. to dramatically lengthen the time needed be-


tween navigational updates of the submarine or even weeks in order to maintain sufficientinertial guidance system. I n the 1990’s, naviga- capability to attack very hard targets from sea.tional updates would not be

INERTIAL

required for days

GUIDANCE AIDED BY RADIO UPDATE

The two sets of accuracy data so far dis-cussed are based on improvements in inertialguidance technologies that are used in missilesand in submarines, and on improved geodeticand gravitational data.

Another set of guidance technologies thatcould be used to obtain high accuracy withsea-based missiles without precise naviga-tional data at launch and extensive gravita-tional mapping is a system based on inertialguidance aided by updates from radio naviga-tion aids.

Radio updates could be taken with the aidof the GPS. They could also be taken with theaid of a system of ground radio beacons CBS(also refered to as an Inverted GPS), that couldbe emplaced on the continental United States.In the event that the GPS is attacked using an-tisatellite weapons, the GBS could providebackup radio navigation aids to the missiles infl ight. Unlike the GPS, the CBS would onlyoperate during a crisis, and could be madecostly to attack by constructing many radiobeacons and decoys.

The sea-launched missile could radio updateits inertial guidance system in three differentways, The missile could take a navigational fixusing GPS to update its inertial guidance sys-tem before it deploys its reentry vehicles fromthe missile’s post boost vehicle (i. e., the mis-sile’s bus). In the event of outage of the CPS,the navigational fix could instead be takenusing the ground beacons. I f the GPS weredestroyed and the ground beacons were usedas a backup system, it would be necessary totake a radio fix through the ionosphere. Thisradio fix might be disrupted if there werenuclear detonations occurring in the iono-sphere. In order to avoid disruptions of thistype, a radio fix could be taken before themissile reaches the bottom of the ionosphere,perhaps at an altitude of about 50 miles.

The first two of these methods should pro-vide MX accuracy at all ranges from Soviettargets. If the GPS were used, missiles could belaunched from anywhere in the submarine de-ployment area. If the ground beacons wereused, system accuracy would be degraded ifthe submarines were not with in 700 to 900 nmiof the continental United States. This degrada-tion would occur due to errors introduced intothe navigational update by poor line of sightgeometry on the ground beacons. Figure 86shows the areas of ocean from which a CE Pmultiplier of one could be achieved if groundbeacons were emplaced on the continentalUnited States, Alaska, Hawaii, and on theAleutian Islands. Figure 87 shows the addi-tional Pacific area from which the same CEPmultiplier could be achieved if the groundbeacons were also emplaced on the islands ofWake, Guam, Kwajalein, Palau, and Tafuna,Samoa.

If the ground beacons were used to updatethe missile guidance system before the missilereached the ionosphere (this update could benecessary if the GPS system had been de-stroyed and the ionosphere was disturbed bythe detonation of nuclear weapons) the sub-marines would have to be within 400 to 500miles of the continental coast if a radio updateis to be possible before the lower ionosphere isreached. Using this method of update, a CE Pmultiplier of 1.0 to 1.5 that of land-based MXmight be achievable. Unfortunately, calcu-lations on this type of update have not beenperformed in detail and a more accurate as-sessment of the capability of this type of up-date is not available.

In summary, a sea-based MX could beguided us ing purely inert ial measurementtechnologies or with inertial measurementtechnologies updated by sighting on stars orradio beacons. The star trackers offer a great


Figure 86.—Ocean Areas That Provide Adequate Line-of-Sight View of Ground Beacons onContinental U. S., Aleutian Islands, Alaska and Hawaii

90.001 I

– 70.00

– 90.00* 10.00 30.00 60.00 90.00 120.00 150.00 180.00 210.00 240.00 270.00 300.00 330.00 360.00

Longitude


advantage in that they are a self contained ele- By deploying a large enough system of groundment of the missile and have been demon- beacons and decoys as a backup to the satel-strated to be highly reliable. Radio beacons on Iite beacons, the risk from Soviet countermeas-satellites, and on land, also can be used for up- ures could be kept small.dating the missile’s inertial guidance system.

TIME ON TARGET CONTROL

If the submarine system is to attack hard Since the smal l submarine would carrytargets with more than one warhead, there is a missi les in external capsules that would beneed to control the time at which warheads ar- Iaunched at different depths under differentrive at targets with a high degree of accuracy. operational conditions, the exact time atThis control is needed so that the detonation which a missile flew out of the capsule couldof the first warhead will not interfere with the possibly effect the arrival of warheads atarrival the second warhead. targets. In practice, this problem could be


Figure 87.—Ocean Areas That Provide Adequate Line”of-Sight View of Ground Beacons onContinental U. S., Aleutian Islands, Alaska, Hawaii, and Selected South Sea Islands

90.00 1

—

m

– 90.00 ~ 1 I I 1 . . I I0.00 30.00 60.00 90.00 120.00 150.00 180.00 210.00 240.00 270.00 300.00 330.00 360.00

L o n g i t u d e


solved by assigning each missi le a time at lofted or depressed relative to the planned tra-which warheads are to arrive at targets. Uncer- jectory). Care would have to be exercised intainties in launch time could then be compen- the design of the fire control and guidancesated for by changing the missile’s trajectory package to assure that this could be done.(i.e., the missile trajectory could be slightly

RESPONSIVENESS OF THE SUBMARINE FORCE

The responsiveness of the submarine force is without warning. The time necessary for thesedetermined by the speed with which an Emer- calculations wou Id be of order a few minutesgency Action Message (E AM) could be trans- and would not be a factor I ikely to delay amitted to the force and the time required for launch.the submarines to launch their missiles. Thecalculation of trajectories to target sets must Therefore, the two time periods that wouldbe performed for both land- and sea-based mis- dominate the ability of the submarine force tosiles if targets are reassigned to a missi le respond rapidly to an EAM would be the time


period needed to receive the EAM and thetime period needed to prepare the submarinefor the launch of missiles. The EAM could bereceived in a pre- attack or transattack periodwithin a few minutes. If the submarines wereordered to execute a preplanned strike, alldata necessary for the strike would be avail-able at the reception of the EAM and the timerequired to initiate the strike would be deter-mined by the time that could be needed tobring the submarines to launch depth. Thistime could be several minutes.

If the ordered attack were not a preplannedoption, there could be two different categoriesof target sets chosen, those that are stored inthe guidance computer and those that are de-signated ad-hoc in terms of their latitude, lon-gitude and height of burst. If the target list re-quired a high data rate link, the VLF link would

ENDURANCE

I n the event of a protracted nuclear ex-change, surviving IC BMs might be required forstrikes weeks or months after an initial ex-change. These forces wouId be executed fromsurviving command and control centers usingwhatever communications c ha n n e Is wereava i I able.

The survival of command and control chan-nels and the availability of communicationschannels during a protracted nuclear exchangeis a common problem for both land- and sea-based forces. However, the endurance of theICBMS themselves would differ with the basingmode.

The small submarine could be constructedto have an at-sea endurance of more than 90days without support f rom tenders . I t i sassumed, based on U.S. Navy operating ex-

COST AND

The small submarine basing concept is envi-sioned as a fleet of 51 diesel-electric sub-marines, each of about 3,300 tons submerged

not be appropriate. In this circumstance, acoded message would be sent over VLF for aparticular submarine, or group of submarines,to come to depth and copy a new target Iistusing the EHF satelIite I ink Alternatively, ifthe submarine force were diesel-electric pow-ered (rather than nuclear powered), the frac-tion of the force that was snorkeling couldreceive the ad-hoc targets as well. After recep-t ion of data, which would take only a minuteor two over the EHF Iink, the submarines couIdimmediately prepare for Iaunch by proceedingto launch depth, provided the strategic weap-on system is configured to directly accept andval idate the data f rom the satel l i te I ink.Launch of the missiles could take place shortIythereafter. The rapidity of response of thesystem couId therefore be of order 10 to 15m i nutes

OF FORCE

perience, that a normal submarine patrolwould last for 60 days. This assumption meansthat for 30 days after an initial attack, no sub-marines would have to return to port. About 5percent of the missiles at sea would be lost dueto missile failures during this time. Sixty daysafter an initial exchange, about half the forcewould still be capable of remaining at sea. Ifthe missiles were not operated in a dormantmode (so that they could be fired on a minute’snotice rather than on an hour’s notice) about10 percent of the missiles could be expected tohave failed at the end of 60 days. Thus, 9weeks after an initial attack, the submarineforce could del iver about 400 warheadsagainst an enemy. By 12 weeks after an ex-change, the number of operational missiles atsea wouId have diminished to zero.

SCHEDULE

displacement. Each submarine would be capa-ble of carrying four externally encapsulatedMX missiles. The submarines would be manned


with a crew of about 45 members and would

o p e r a t e w i t h i n 1 , 0 0 0 t o 1 , 5 0 0 n m i o f t h r e ebases. One of the bases would be located onthe east coast of the continental United States,another would be on the west coast, and thethird would be located on the coast of Alaska.

The acquisition cost of the system of sub-marines, bases, navigational aids, and relatedoperational and support equipment is esti-mated to be about $32 billion (fiscal year 1980dollars). An operating and support cost of $7billion is estimated for a 10-year system life-cycle, The total cost of the system is estimatedto be about $39 billion. The details of this costestimate at the major subsystem level is pre-sented in table 27.

The deployment schedule for a system ofsmall submarines is shown in figure 88. Thisschedule would vary with the degree of com-mitment the nation makes to a new strategicweapon system. If the commitment is suchthat slippage is not allowed due to unforeseentechnical setbacks, funding cuts, environmen-tal law suits, or other actions that could re-quire congressional action, an initial opera-tional capability (IOC) in the middle of 1988could occur. It could even be possible to havea lead ship by the end of 1987, but this wouldrequire a very high degree of national commit-ment. A more realistic estimate based on areview of military programs over the pastdecade would place IOC in 1990. If IOC oc-

Table 27.—Small Submarine 10-Year Lifecycle Cost(billions of fiscal year 1980 constant dollars)

Cost element Number costRDT&E:

Submarine. . . . . . . . . . . . . . . . . . — $0.422Missile . . . . . . . . . . . . . . . . . . . . — 6.056Sws . . . . . . . . . . . . . . . . . . . . . . . – 0.400Capsule . . . . . . . . . . . . . . . . . . . . — 0.257Navigational aids . . . . . . . . . . . . — 0.090— . —

Total RDT&E . . . . . . . . . . . . . . . . . . . . . . . . . $7.225Procurement:

Submarine. . . . . . . . . . . . . . . . . . 51 $ 6.682Basing . . . . . . . . . . . . . . . . . . . . . 3 7.240Missile . . . . . . . . . . . . . . . . . . . . . 470 5.419Sws . . . . . . . . . . . . . . . . . . . . . . . 51 2.397

Capsule . . . . . . . . . . . . . . . . . . . . . . 521 1.725Navigational aids . . . . . . . . . . . . . . 1,500/3,000 1.399

Total procurement . . . . . . . . . . . . . . . . . . . . - $24;862

Total acquisition. . . . . . . . . . . . . . . . . . . . . . . . . . $32.087

Operating and support:IOC to FOC . . . . . . . . . . . . . . . . . . . . . . . . . . . . $ 2.392FOC to year 2000 . . . . . . . . . . . . . . . . . . . . . . . 4.868

Total operating and support . . . . . . . . . . . . . . . . $ = . 1 6 0Total to year 2000 LCC. . . . . . . . . . . . . . . . . . . . . $39.247—

Average acquisition $/submarine, . . . . . . . . . . . $ 0 . 6 2 9Average LCC/submarine to year 2000. . . . . . . . . 0.770Average acquisition $/deployed missile . . . . . . 0.157


curred in 1988, full operational capability(FOC) could be achieved in late 1992. If themore realistic estimate of a 1990 IOC occurs,FOC would occur in early 1994.

It should be noted that the costing of thesubmarine system assumes Navy procurement

Figure 88.—Small Submarine Program Schedule

.; * . -.% .“ ‘ . ., ,

Missile avaikblllty ‘ : ‘ . . ‘e ‘ .“‘. ~ *: .$ *., - , - . ., >. j

B a s e m $ w * J q , . * -,i ’ .’-..

Submarine $ ~,Head ship proc. AInitial operations (IOC) AFull operations (FOC) (Ioc) A

(FOC)



practices for the MX missiles. In order to have100 missiles alert at sea at all times 470 mis-siles are obtained. The land-based Air Forcebaseline procures 330 missiles. The additionalmissiles are obtained since it is assumed thatNavy experience developing sea-based missileswould apply to the MX if it were deployed atsea. These missiles would be used in an exten-sive program of testing and evaluation similarto that of the Trident/Poseidon programs.

It should also be noted that three bases areincluded in the costing. Since the submarinespostulated for this system would have a con-siderable at-sea endurance, it would be possi-ble to deploy them from two bases instead ofthree. However, each of the bases would haveto be larger in order to handle additional sub-marines. These bases would normally servicenine to ten submarines instead of six to seven.

SYSTEM SIZE

The number of submarines acquired waschosen so that 100 MX missiles would be avail-able at sea for retaliation against the SovietUnion regardless of preemptive actions ontheir part. The choice of 100 surviving missileswas arrived at using the following reasoning:

The number of small submarines requiredfor a sea-based MX system is determined bythe perceived need to be able to attack apredetermined number of targets after anyenemy action. The number of targets that theUnited States could attack after a Soviet firststrike would depend on the number of missilesthat survive such an attack.

It is assumed that all at sea-submarineswould effectively survive an ICBM attack. Thisassumption is based on a review of the capabi1-ities of antisubmarine technologies and forces.A barrage attack is not considered a significantthreat for the following reasons:

The Air Force MX/MPS baseline has 200 mis-siles hidden among 4,600 shelters. For purposesof analysis, it is assumed that half of the Iand-based MX force will survive a determinedSoviet attack. This assumption would meanthat no more than 2,300 hard target capablewarheads landed in the MX/MPS fields closeenough to shelters to destroy them. A barrageattack with this number of warheads mightresult in the destruction of one to two sub-marines at sea. This does not represent asignificant attrition of the submarine force.

The number of small submarines required tomaintain 100 missiIes at sea in an “up” status is

determined by the number of missiles per sub-marine Mps, the fraction of missiles in an “up”status Fmu the fraction of the time a sub-marine is at sea during a patrol cycle Fas thefraction of submarines that are in overhaul oron restricted availability For and the fractionof submarines that are expected to survive anat-sea attack Fss. The total number of smallsubmarines N required to maintain 100 missiIesis then given by:

N 100

whereN = the total number of submarines required to deliver

1,000 RVSMps = the average number of missiles per submarineF = the fraction of submarines in overhaul or restricted

avaiIabiIityt = the traction of time submarines are at sea during a,,.

patrol cycleF mu = the fraction of missiles In an “up” status at seaF \\ = the fraction of the at sea submarines surviving

after an attack

Since the missiles would be in capsules ex-ternal to the hull of the submarine, they couldnot be serviced while the submarine is at sea.Hence, the failure of a missile at sea would putit in a down status for the remainder of the at-sea patrol.

The fraction of missiles available at sea dur-ing a patrol period of T days wilI be:

1 s T – (It

I

where 7 Is the mean t I me between failure o fthe missile and the is the Iength of time of the sub-marines is on patrol

Ch. 5—Small Submarine Basing 01 MX ● 213

Since each submarine will spend T days atsea and TIP days in port, the at sea availabilityof the submarine during a normal patrol cycleIs:

F l\T + ,,,

If a submarine spends 12 months in overhaulor in restricted availability during each 5-yearoperating period, then O = 0.8.

Table 28 presents the number of submarinesthat would be required to maintain 100 mis-siles on station for different patrol periods atsea and for different times in port for refit. It is

Table 28.—Number of Submarines Required To Keep100 MX Missiles Continuously on Station v.

Submarine In-Port Time

Patrol period (days). . . . . . . . . . 40 50 60Number of submarines at sea . 26 26 27Total submarine force size:a

12 days in port . . . . . . . . . . . . 42 (40) 41 (38) 40 (38)15 days in port . . . . . . . . . . . . 45 (42) 43 (40) 41 (39)18 days in portb . . . . . . . . . . . 47 (44) 45 (42) 43 (41)21 days in port . . . . . . . . . . . . 50 (47) 47 (44) 45 (45)24 days in portc . . . . . . . . . . . 52 (49) 49 (46) 46 (44)

a Total force numbers assume that 20 percent of att submarines will be inextended refit or overhaul and are therefore unavailable Numbers in parentheses assumes 15 percent of the force in overhaul or extended refit.

b Naval Sea Systems Command estimates minimum time in Port required for

refit IS 18 days.c OTA assumes 25 days in port for refit and handling of missiles


assumed that 100 percent of the submarinessurvive preemptive enemy action and that 20percent of the submarine force is either under-going overhaul or is in restricted availability.The numbers in parentheses assume 15 percentof the submarines are in overhaul or restrictedavailability instead of 20 percent. Thus, if itproved feasible to perform refit operations in18 days (instead of OTA’S assumed 25 days)and to have 15 percent of the submarines inoverhaul and extended refit, it would be possi-ble to maintain 100 missiles on station with afleet of 41 submarines, rather than the 51 sub-marines assumed by OTA. The at-sea factor isthe fraction of the submarine force that isalways at sea. It is defined as:

at-sea factor = F<,, (1 – F,,)

An at-sea factor of 55 percent is assumed inorder to estimate the total number of requiredsubmarines. This factor is also used to estimatethe number and size of base facilities requiredfor servicing submarines between patrols.

In order to provide 100 at-sea missiles (or al-ternatively 1,000 surviving warheads) at alltimes, the at-sea reliability of the missiles mustbe factored into the sizing of the fleet. It is pro-jected, from engineering requirements, that 95percent of the missiles at sea would be in an upstatus for a fleet of submarines with an at-seapatrol of length 60 days.

FINAL SIZING CONSIDERATION

In the final sizing of the system, it wasassumed, in order to establish a conservativecost estimate, that 10 percent of the missilesmight not function on a launch command andit would be necessary to maintain more than100 “up” missiles at-sea. This assumption

added 4 submarines to a procurement whichwould otherwise have been 47. The costs ofprocuring, operating and supporting additionalcrews, missiles, capsuIes, and strategicweapons systems is of the order of $1 billion to$2 billion.

LOCATION AND DESCRIPTION OF BASES

Base selection was limited to the continen- The perceived need for responsiveness, flex-tal United States since the submarine force is ibility, and weapon system effectiveness dic-designed to operate in deep ocean areas adja- tated that the submarines be able to movecent to the continental United States. rapidly to acoustic transponder fields to main-


tain accuracy in the event of outage of theGPS. A very large operating area would spreadthe acoustic transponder fields over a largearea of ocean, resulting in possible executiondelays due to long transits to transponderfields. In addition, time on station could bemaximized without the need of a submarinewith a high transit speed. It should be noted,however, that none of the above considera-tions truly dictate a need for such a limiteddeployment area.

The Gulf of Mexico was rejected as a de-ployment area for the folIowing reasons:diesel-electric submarine technology hasachieved a level of quieting that would notrestrict the submarines to acoustically shallowwater even if a large-scale advanced passivesonar threat emerged. The acoustically shal-low water of the Gulf of Mexico therefore of-fered no clear survivability benefits to offsetthe range/payload/accuracy missile perform-ance penalties associated with that deploy-ment area.

It is assumed that a detailed review of possi-ble base locations would be made if there wasa decision to deploy a fleet of small sub-marines. In order to provide a basis for esti-mating costs, three base locations on the eastand west coasts of the continental UnitedStates and Alaska were assumed. These are:

. Anchorage, Alaska

. Puget Sound Area, Wash.,● Narragansett Bay, R. 1.Each of the sites has problems of its own.

The arctic winters, long winter nights, and ex-treme weather at the Anchorage site wouldpose problems clearing ice, loading and offloading missiles, maintaining and refitting sub-marines, and supporting crews at the base. ThePuget Sound area already has a Trident base(Bangor, Wash.). Construction at the Narraga-nsett Bay site could be delayed due to competi-tion for the land from the Rhode Island Gov-ernment.

Other possible secondary sites could be:● San Diego, Cal if.,● Charleston, S. C.,● Kingsbay, Ga.

These possible sites also offer their ownproblems. San Diego would be unlikely to pro-

vide enough waterfront area without displac-ing existing Navy operations. Charleston andKingsbay could be too far south for the mostefficient deployment of submarines in thenorthern coastal areas of the Atlantic.

Since SSBN fleet support is shifting to Kings-bay, waterfront area may become available inCharleston for submarine support in Charles-ton while MX support might be provided at thenew SW FLANT facility at Kingsbay. Tradeoffstudies would have to be performed in order toevauate the sensibiIity of these options.

In order to develop a conservative estimateof the size, number, and cost of facilities at thesmall submarine base, an analysis of the Tri-dent base facility at Bangor was made. Approx-imately 85 to 90 percent of the Iand requiredfor the base is dictated by explosive weaponssafety requirements and facilities for handlingstrategic weapons. It was assumed that theamount of land required scaled with the num-ber of strategic weapons on the base. Thisnumber includes the missiles on the subma-rines, missiles stored for operational tests, andmissiles stored for demonstration and shake-down operations. These assumptions lead tothe conclusion that 4,450 acres would be re-quired for the base. other assumptions couldlead to a smaller less costly base but theywould only be justified if a more detailed feasi-bility analysis could be performed.

The size of the base arrived at for thecosting analysis is approximately 500 acreslarger than a base sized in an earlier study ofsmall submarine basing performed by the Sys-tem Planning Corp. for the Navy. Table 29compares the estimated small submarine basewith the Trident base at Bangor.

Table 29.–Estimated Characteristics of the SmallSubmarine Refit Site and the Trident Refit Site

Smallsubmarines Trident

Total area (acres) . . . . . . . . . . . . . . . . . 4,450 8,397Waterfront length (feet). . . . . . . . . . . . 11,630 4,248Number of submarines in port . . . . . . 5/6 3Number of explosive handling

wharfs . . . . . . . . . . . . . . . . . . . . . . . . 1 2Number of refit berths. . . . . . . . . . . . . 4/5 3Drydockets/graving docks . . . . . . . . . 1 1SOURCE Off Ice of Technology Assessment.

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Small Submarine Basing of MX