overview of the lincoln laboratory ballistic missile defense program

VOLUME 13, NUMBER 1, 2002 LINCOLN LABORATORY JOURNAL 9

• LEMNIOS AND GROMETSTEINOverview of the Lincoln Laboratory Ballistic Missile Defense Program

W unprecedentedburgeoning of applied technology insupport of the armed forces of the major

nations at war [1–2]. With few exceptions, previouswars had been fought throughout with the weaponsand technology available at the onset of hostilities. InWorld War I, for example, there are few instances ex-cept for the development of military aircraft, in whichsignificant technological development was made byany combatant [3].

In World War II, on the other hand, significanttechnological innovation pervaded most every aspectof combat. An outstanding example is radar. Inaccu-rate, low powered, and unreliable when invented inthe early 1930s, it became sophisticated, high pow-ered, and dependable in the following decade. Associ-ated with radar was the development of aiming andcomputing devices that permitted rapid, accurate,and semiautomatic fire control. Allied superiority inthe field of radar played an important role in deter-mining the outcome of the war.

During the war, two civilian laboratories operated

Overview of the LincolnLaboratory Ballistic MissileDefense ProgramWilliam Z. Lemnios and Alan A. Grometstein

■ The technical challenge that resulted in the creation of Lincoln Laboratorywas to combine dispersed radars and computers into a system to defend thecontinental United States against attack by fleets of strategic bomber aircraft.The problem of air defense emerged from the end of World War II as one of themore serious threats against the security of the United States. Within a decade,the problem of air defense was transformed into one of providing a defenseagainst attack by ballistic missiles, a problem that has engaged the Laboratory’sattention ever since. This issue of the Lincoln Laboratory Journal records thehistory of the Laboratory’s engagement in ballistic missile defense (BMD); thisarticle provides an overview of the Laboratory’s role. Other articles in this issuetreat specific aspects of the Laboratory’s BMD work in more detail.

by MIT evolved as centers of expertise in military ap-plications of radar and its associated technology.From the Radiation Laboratory, or RadLab, and theServomechanisms Laboratory, or ServoLab, cameprototypes of the components and complete radarsystems that would later appear in production quanti-ties in the war effort [2].

By 1945, radar technology had progressed fromcrude bench-model demonstration apparatus to ver-satile systems that operated reliably on land, air, andsea. When the war ended, however, the RadLab wasperceived as having served its purpose and was conse-quently closed [4]. In the same spirit, activities at theServoLab were curtailed. In light of political develop-ments in eastern Europe after the war, closure of theRadLab was seen post facto as a loss of a nationaltechnological asset. Concern mounted that the mo-mentum of pursuing improvements in radars hadbeen lost, just as it became clear that the ability to de-fend the continental United States against attack bystrategic bombers in all likelihood had to depend onradars.


10 LINCOLN LABORATORY JOURNAL VOLUME 13, NUMBER 1, 2002

From the end of World War II in 1945 to the early1950s, the greatest effort by far in strategic defense ofthe United States was concentrated on continental airdefense. U.S. intelligence agencies at that time con-cluded that the USSR possessed long-range bomberaircraft and had, in September 1949, exploded anatomic weapon. Concerns about this threat led to thegenesis of Lincoln Laboratory in 1951; theLaboratory’s mission was initially air defense. It is notthe purpose of this paper to describe in detail the sev-eral studies and subsequent recommendations thateventually led to the formation of Lincoln Labora-tory. That story, as well as details of the Laboratory’searly years, is ably recorded in Reference 1. We brieflysummarize the Laboratory’s efforts in air defense inthe early 1950s, since these formed a prelude to laterLaboratory work in ballistic missile defense (BMD).Readers interested in more details in these efforts aredirected to References 1 and 5; the latter referenceprovides unique insights into this work by an engi-neer directly involved.

Concerns About Air Defense

Early air defense systems, such as the radar defensesmounted in England against bombing attacks by theLuftwaffe, were critically dependent upon calcula-tions and decisions made by humans at several pointsin the system. Trained operators performed interpre-tation of radar data, establishment of tracks on bothbombers and interceptors, and issuance of engage-ment vectors to interceptor pilots. The developmentof digital computers—in particular, their increase inspeed and versatility—made it feasible to conceive ofintegrating computers within a radar-human systemto render a faster and more accurate response.

The concept of integrated air defense emergedfrom a committee organized by the Air Force Scien-tific Advisory Board (AFSAB) in December 1949,which became known as the Air Defense Systems En-gineering Committee (ADSEC). The committee, op-erating under the chairmanship of George E. Valley,Jr., of MIT, shown in Figure 1, concluded that air de-fense of the continental United States against the So-viet strategic-bomber threat could only be accom-plished by integrating data from numerous radarsinto a single powerful computer, and by carrying out

the functions of surveillance, tracking, and intercep-tor direction in real time, with a minimum of manualinterventions. Whether radar, communications, andcomputer technologies could enable such an integra-tion effort was settled by a demonstration in Septem-ber 1950, when a radar at Hanscom Air Force Base inBedford, Massachusetts, tracked an aircraft and trans-mitted the resulting analog signals, converted to digi-tal signals, over telephone lines to the Whirlwind Icomputer at MIT in Cambridge, Massachusetts [6].Three months later, the success of this demonstrationinfluenced Gen. Hoyt S. Vandenberg, Air Force Chiefof Staff, to write James R. Killian, Jr., President ofMIT, proposing the establishment of a laboratorydedicated to air defense.

FIGURE 1. George E. Valley, Jr. (1913–1999), chairman of theAir Defense Systems Engineering Committee. Valley spentWorld War II at the MIT Radiation Laboratory, where he de-veloped the H2X radar bombsight. After the war, he joinedthe physics faculty at MIT, where he studied the integrationof radars and computers in extended defense systems. Hewas associate director of Lincoln Laboratory from 1949 to1957 and Chief Scientist of the Air Force from 1957 to 1958.



MIT immediately convened a group of scientiststo study and evaluate this proposal. The group,named Project Charles (after the river in Boston),studied the proposal from February to August 1951,then issued a report that became the basis of the even-tual air-defense system. The report favored develop-ment of an integrated, automated defense system butrequired that before work begin on the full-scale con-tinental air defense system, a scaled-down version beconstructed, tested, and evaluated. The scaled-downeffort became known as the Cape Cod System.

Because Project Charles had been an ad hoc study,MIT decided to pursue further efforts in air defenseon an ongoing basis, and therefore established ProjectLincoln—eventually Lincoln Laboratory—in July1951 [7]. This decision by MIT was supported bythe Air Force when in February 1952 Secretary of theAir Force Thomas K. Finletter promised substantial

funding to the university for the laboratory. Initially,Lincoln Laboratory was referred to as a federal re-search center, then as a Federal Contract ResearchCenter, and is now officially a Federally Funded Re-search and Development Center (FFRDC) (see thesidebar entitled “Lincoln Laboratory as an FFRDC”).

The new laboratory was unabashedly an offspringof the RadLab. The administrative structure of Lin-coln Laboratory mirrored that of the RadLab—aDirector’s Office overseeing about ten divisions, eachspecialized in one field of technology, with the divi-sions subdivided into groups of five to twenty techni-cal staff. The first director of Lincoln Laboratory wasF. Wheeler Loomis, a former associate director of theRadLab. The personnel categories (staff, associatestaff, assistant staff ) duplicated those of the RadLab,which itself had taken these categories from the aca-demic world of MIT.

L I N C O L N L A B O R A T O R Y A S A N F F R D C

Research andDevelopment Centers (FFRDC)are institutions that work in thepublic interest and receive thebulk of their funding from agen-cies of the federal government.There are currently thirty-sixFFRDCs sponsored by the De-partment of Defense, Depart-ment of Energy, National Aero-nautics and Space Adminis-tration, Department of Healthand Human Services, NationalScience Foundation, NuclearRegulatory Agency, Departmentof Transportation, and Depart-ment of the Treasury.

The first of these institutionswas established in the early 1940sas federal research centers. Subse-

quent centers came to be knowninformally as Federal ContractResearch Centers (FCRC), al-though the name Federally Char-tered Research Centers was alsoused. The use of Department ofDefense FCRCs grew out ofsemiacademic laboratories andresearch groups created by thefederal government for defenseresearch during World War II.They are now called FFRDCs.

By law, FFRDCs are used onlyto meet special research or devel-opment needs that cannot be metas effectively by existing federalgovernment or contractor re-sources. The FFRDCs have aspecial long-term partnership re-lation with their sponsors, em-

phasizing independence andcommitment, and they provide abody of technical expertise thatcannot be sustained within theCivil Service. The FFRDCs arenot-for-profit activities and oper-ate under restrictions that pro-hibit the sale of products andcompetition with for-profitindustry.

The Department of DefenseFFRDCs are viewed as being inthree categories, with differentfunctions: (1) studies and analy-sis centers; (2) laboratories; and(3) system engineering and tech-nical direction centers. LincolnLaboratory falls in the second ofthese categories.



Work on the Cape Cod System began immediatelywith the establishment of Project Lincoln. In January1953, Project Lincoln issued a substantial designdocument that detailed how the Cape Cod Systemwould operate to defend southern New England fromair attack. Signals from three long-range (AN/FPS-3)radars, eleven gap-filler radars, and three height-find-ing radars would be converted from analog to digitalformat and transmitted over telephone lines to theBarta Building (shown in Figure 2) in Cambridge,Massachusetts, which housed the Whirlwind I com-puter (shown in Figure 3). That computer would es-tablish and maintain tracks on aircraft, perform anidentification process, and issue instructions to en-

able interceptor aircraft to intercept the nonfriendlyaircraft. The digitized radar and track informationwould be displayed on interactive consoles monitoredby Air Force personnel, who relayed the directionalcommands to the interceptors. (Later in the develop-ment of the Cape Cod System, such commands wererelayed directly to autopilots in the interceptors.) Theinitial version of the Cape Cod System became opera-tional in September 1953, some two-and-a-half yearsafter its inception, and underwent testing and evalua-tion over the next four years.

Initial tests of the Cape Cod System used onlysimulated data, but later tests employed bombers sup-plied by the U.S. Air Force, with real interceptorsclosing on them. During these tests, flights of B-47smade simulated attacks against points in eastern NewEngland, and the Cape Cod System attempted inter-cepts, utilizing interceptor aircraft scrambled fromfour Air Force bases. The results were promisingenough to confirm the soundness of the air defenseconcept envisioned by Project Charles. The decisionwas made, therefore, to implement the full air defensesystem, which was called the Semi-AutomaticGround Environment (SAGE) Air Defense System. Itwas begun by Lincoln Laboratory and was later engi-neered and developed by the MITRE Corporation.(MITRE is a separate corporate entity that was

FIGURE 2. The Barta Building on Massachusetts Avenue,Cambridge, home of the Whirlwind I computer.

FIGURE 3. The Whirlwind I computer console room in 1950. Seated at left:Stephen Dodd, Jr. Standing: Jay Forrester, left, and Robert Everett, right.Seated at the right: Ramona Ferenz.



formed in July 1958 and staffed with a cadre of per-sonnel from Lincoln Laboratory with experience onthe Cape Cod System.)

Lincoln Laboratory’s work on air defense providedvaluable training for its later work in BMD. TheCape Cod System was the first large-scale militarysystem controlled in real time by a digital computer.The experience gained in such areas as track initiationand maintenance, weapon assignment and interceptprediction, battle management, and data fusion (tolist just a few fields of development), served as a basisfor much of the BMD work undertaken later by theLaboratory.

Concerns about Ballistic Missile Defense

The closing year of World War II in Europe witnessedintroduction of the first generation of cruise missilesand ballistic missiles as weapons of terror and intimi-dation. Germany launched its first cruise missile(V-1) against England in June 1944. Three monthslater, Germany began launching ballistic missiles(Aggregat 4, or V-2). From the first firing until Alliedforces captured the launch sites in Belgium and theNetherlands on the Channel coast in March 1945,some 21,000 V-1s and 4300 V-2s were launched.These relatively short-range missiles (~300 km), car-rying payloads of 850 to 1,000 kg of high explosives,could not be precisely aimed but were used to terror-ize civilian targets in large cities [8]. The BritishHome Defense Command found that protectionagainst the slow V-1 was feasible with the normal de-fenses used against manned aircraft; indeed, many V-1s were shot down by interceptor aircraft and antiair-craft guns. However, no defense was possible againstthe much faster V-2, and only the capture of thelaunch sites in March 1945 stopped the destructionthese missiles caused.

Military planners after the war realized the crucialrole that ballistic missiles could play in future con-flicts, and efforts began in several countries (primarilythe United States and the USSR) to increase the rangeand payload of these weapons and to improve theirtargeting accuracy. With the emergence of nuclear fis-sion bombs in 1945 and of nuclear fusion bombs in1949, the ultimate weapon envisioned was a ballisticmissile capable of traveling intercontinental distances

while carrying a nuclear warhead—the intercontinen-tal ballistic missile (ICBM). By the early 1950s, de-velopment efforts of such a weapon were well under-way, and by the latter half of the decade, ICBMsbegan to enter the U.S. strategic force structure. On26 August 1957, the USSR announced a successfulICBM test, which was followed on 4 October 1957by the launch of Sputnik I, the first man-made satel-lite [9]. In response to these events, the United Statesbegan developing the Nike-Zeus system to defend cit-ies against ICBMs in the 1950s. (The first successfullive intercept occurred in July 1962.) This early BMDsystem was basically an improvement on existing airdefense elements, such as Nike-Ajax and Nike-Her-cules, which were emplaced earlier to guard againststrategic bombers.

Although there are similarities between air defenseand BMD in the use of radars and interceptors con-trolled in real time by large computers, there are alsosignificant differences. A key difference is the speedsof the oncoming threat objects. An ICBM travels at20,000 to 25,000 kph, depending on type and mis-sion; a strategic bomber travels at speeds of 1000 to2500 kph, depending on type and mission. Thehigher speeds of ICBMs compress the battlespace,which is the interval—measured either in range orduration—between the defense’s first and last oppor-tunities to take effective action against an approach-ing threat object. To compensate for the compressedbattlespace, the defense must detect ballistic missilesat longer ranges, which requires more powerful ra-dars, and must automate such critical functions asweapon allocation and fire control.

Another key difference between air defense andBMD is the more prominent role of countermeasuresin BMD. In 1958, Lincoln Laboratory, which hadtransferred responsibility for SAGE to MITRE, wasasked by the Advanced Research Project Agency(ARPA) of the Department of Defense (DoD) to be-gin related research efforts in BMD. Ballistic missilescan and often do embody a variety of tactical devicesintended to confuse the defense and facilitate thewarhead’s penetration of the defense. Among thesedevices are chaff and electronic countermeasures,both of which act to create radar clutter or noise. Inaddition, decoys of various shapes and compositions,



which are intended to mimic the signatures and met-ric characteristics of the warheads, may accompanythe missiles. The process of tracking bodies in thepresence of clutter and then discriminating (that is,identifying and selecting) the warhead from all otherobjects is one of the most difficult and most impor-tant technical problem faced by BMD system design-ers. It was in this area that ARPA asked the Labora-tory to initiate research, an area that we discuss ingreater depth in subsequent sections of this article.

Historical Overview ofU.S. Ballistic Missile Defense

Before proceeding with a description of LincolnLaboratory’s work in BMD, it is instructive to give anhistorical overview of the national effort in BMD.Figure 4 summarizes the U.S. effort in BMD over theyears. Figure 5 is a more detailed two-page timelineshowing Lincoln Laboratory’s contributions to ballis-tic missile defense programs.

The task of developing BMD systems was initiallythe responsibility of the U.S. Army and of ARPA.The Army (with Bell Laboratories as the system con-tractor) was responsible for building and testingBMD system components, and eventually deployingthem in the vicinity of major U.S. population centers.ARPA was responsible for concentrating on majortechnical problems, whose solutions were to be inte-grated into the deployed BMD systems.

In 1957, little technology was available to addressthe problems of BMD. Narrow-bandwidth dish ra-dars operating in the VHF, UHF, and L-band fre-quencies had been built for air defense; however, ameans to intercept the warhead of a fast incomingICBM did not exist. Computers built for air defensehad only begun to address the problem of distin-guishing enemy aircraft from natural clutter andnoise. The Nike-Zeus system employed separate dishradars for surveillance, target tracking, and intercep-tor guidance. It suffered from two major deficiencies:a limited traffic-handling capability and an inabilityto discriminate warheads from decoys and other ob-jects at high altitudes [1]. (For successful defense ofcities, discrimination must be performed at high alti-tudes.)

In the 1960s, a new Army system called Nike-X

was developed specifically for BMD. Nike-X, as wellas its later versions, Sentinel and Safeguard, were de-signed primarily for city defense. These systems werealso envisioned at various times to be used for areadefense and hard-site silo defense. Nike-X used twoelectronically scanned phased-array radars for its op-erations, and two types of interceptors: a long-rangeinterceptor able to destroy warheads at long distances,and a high-acceleration short-range interceptor thatallowed the system to wait until the atmosphere hadeffectively filtered out all objects except the warhead.Both interceptors were tipped with nuclear warheadsthat could destroy all objects within their lethal ra-dius. The Nike-X phased-array radars, which couldredirect their beams in microseconds instead of sec-onds, significantly increased traffic handling.

The offense missile systems were initially simple indesign, few in number, and lacking any sophisticatedpenetration aids (penaids) to create false interceptpoints. Thus discrimination could be performed withsome success by using only narrowband radar crosssections and little in the way of computer resources.But as the number of Soviet ICBMs grew and the so-phistication of putative countermeasures increased,no U.S. technology solution appeared capable of de-fending cities against a massive attack by ICBMs.There was also considerable concern about the collat-eral effects of multiple nuclear weapons detonatingduring an engagement. Consequently, a doctrine ofcounterstrike, or mutual assured destruction (MAD),was adopted in lieu of city defense. By 1970, theUnited States began to deploy ICBMs within buriedsilos for protection. At about the same time, contractswere awarded for construction of Safeguard anti-bal-listic missile sites in Montana and North Dakota. In1972, the United States signed the Anti-Ballistic Mis-sile (ABM) defense treaty with the Soviet Union,which allowed only one site for each country, and allSafeguard construction activities were suspended inMontana. The treaty limited the scope of any ABMdeployment, so that not all cities in the United Statescould be defended. In October 1975, shortly afterSafeguard achieved an initial operating capability, theU.S. Congress decided to deactivate the system.

Attention then turned to defending U.S. ICBMsagainst a preemptive Soviet missile strike. Defending



FIGURE 4. Timeline of the U.S. national effort in ballistic missile defense (BMD). During an approximately forty-five-year pe-riod, the U.S. objectives in ballistic missile defense have undergone several changes. The objectives were influenced by the na-ture of the threat and by the state of the required technology. The above figure lists the BMD missions and the systems pro-posed to meet the missions. For a more detailed timeline showing Lincoln Laboratory’s contributions to ballistic missiledefense programs, see Figure 5.

silos rather than cities became the goal, and a new sys-tem called Site Defense was designed. (Although nocomponents of this system were ever deployed, a pro-totype Site Defense radar was built on KwajaleinAtoll in the Marshall Islands in the late 1970s.) De-fending hardened silos allows intercepts deep withinthe atmosphere, thus providing more time to detectan incoming threat and to discriminate the warheads.Upon reentry into the atmosphere, launch hardware,debris, and light exoatmospheric decoys slow downand fall away from the faster-traveling warhead andcan be discriminated from it. Heavy endoatmo-spheric decoys that do not slow down until deeperinto atmospheric reentry can be discriminated later.Further, as atmospheric scientists had long known bystudying the radar trails of meteors, the plasma bowshock and ionized wake of reentering bodies could bedetected by radars and used to characterize them.Such characterization requires wideband (severalhundred MHz) phased-array radars that could resolvesmall sections of the ionized wakes. Development ofthese radars began at the Laboratory in the late 1960s.

On 23 March 1983, President Reagan announcedthe beginning of the Strategic Defense Initiative(SDI). The President asked “Would it not be better tosave lives than to avenge them?” suggesting that inter-national stability could be achieved better through

BMD than MAD. To accomplish this formidabletask, he directed the beginning of a long-term re-search and development effort. Large amounts offunding were provided to reinvigorate the missile de-fense effort and a new organization, the Strategic De-fense Initiative Organization (SDIO), was formed tomanage and direct the programs. Renewed attentionwas given to discrimination, with emphasis on space-based sensors and directed-energy weapons. Nowmissiles were to be discriminated during boost phase,while separating from their booster, and during theirentire midcourse flight as well as in reentry. Theselong timelines allow radars to image objects and tomeasure their motion with great precision. For re-solved targets, space-based infrared (IR) telescopescould measure thermal properties. At about the sametime, the United States adopted a doctrine not to usenuclear-tipped interceptors. This doctrine signifi-cantly reduced an interceptor’s lethal radius, and re-quired precision guidance of the non-nuclear inter-ceptors.

50s 60s 70s 80s 90s 00s

Major BMDMission

ProposedU.S. BMDSystems

LightAreaDefense

City Defense Defense of MM/MX

HeavyAreaDefense

LightAreaDefense

TheaterDefense

NationalDefense

Nike Zeus Safeguard SDI

Phase 1Site DefenseNike-X

GPALSSentinel Sentry

TMD/NMD BMDS

FIGURE 5. (overleaf) Events and achievements of LincolnLaboratory’s program in BMD. The chart is a time-orderedlisting of major Laboratory contributions to BMD. Alsoshown are major events that influenced the focus of U.S.BMD.



System Studies

1955 1960 1965 1970

1955 1960 1965 1970

1975

1975

Microwave and Laser Radars

Visible and Infrared Sensors

Laboratory Experiments and Field Tests

Data Analysis and Modeling

National BMD Program Events

Reentry Physics Program

Millstone Hill Radar Operational (UHF)

Project PRESS

Penetration Aids Program

Millstone Hill Radar Modified

Kiernan Reentry Measurements Site (KREMS) Dedicated

(Kwajalein)

Army BMD Program

Kwajalein Missile Range (KMR)

Phased Array Studies

Arbuckle Neck S-Band Tracker Operational

(Wallops Island)

TRADEX Radar Operational (Kwajalein)

AMRAD Radar Operational (WSMR)

Radar Test Bed Array (LL)

Waveguide Ferrite Phase Shifter

Frequency-Stable CO2 Laser

Firepond Laser Radar Operational

ALCOR Radar Operational (Kwajalein)

ALTAIR Radar Operational (Kwajalein)

TRADEX Radar Modified-L, S-Band

500J Electron-Beam Excited CO2 Laser

Schmidt Cameras (Wallops Island)

Tracking Spectrometer (Wallops Island)

PRESS Ground Optics (Kwajalein)

PRESS Airborne Optics

Air Force KC-135, Navy A-3D

(Kwajalein)

Long Wavelength IR Detectors

InSb Photodiodes

Army Optical Station-SOLITAIRE, GBM

(Kwajalein)

Trailblazer Tests (Wallops Island)

Reentry Simulation Range (LL)

REDD System (Kwajalein)

SIMPAR Modification for ALTAIR

Have Jeep Tests (Kwajalein)

First Thermal Blooming Experiments

Project Lunar See (Measurements

on the Moon)

Reentry Phenomenology

Precursor Plasma Modeled

Clean-Air Wake Chemistry Modeled

Structure and Statistics of Turbulent Wake

Measurements

Bulk Filtering

Near-Wake Phenomenology

Measured

SKYLAB Radar Images

First Successful U.S. ICBM Flight

First Successful USSR ICBM Flight

Sputnik (USSR)

Explorer I (US)

Formation of MITRE Corporation

First Successful Live Intercept by Nike Zeus

Nike-X System

Adoption of Mutually-Assured Destruction

(MAD) Doctrine

Sentinel System

Strategic Arms Limitation Treaty

(SALT)

Safeguard System Deployed at

Grand Forks, ND

Intercept-X Studies

Radar Study (High Frequency,

Wide Band)

Sentinel Studies

Single Silo Hardpoint Defense

Laser Atmospheric Propagation Interactions

Space Object Surveillance Study

Lincoln LaboratoryBallistic Missile Defense (BMD)

and BMD-Related Programs



1975 1980 1985 1990 1995 2000 2002

1975 1980 1985 1990 1995 2000 2002

Haystack Long Range Imaging Radar (LRIR)

Operational

Optical Aircraft Measurements

Program (OAMP)

Optical Discrimination Technology (ODT)

Program

Navy BMD Program

Termination of ODT Program

Haystack Auxiliary Radar (HAX) Operational

Standard Missile Program

Project Hercules

National Missile Defense

Kinetic Boost Phase Intercept Program

Design Studies for Cobra Judy

LRPA Installed (Firepond)

LITE Laser Radar Operational (Kwajalein)

SAW Processor at ALCOR

MMW Radar Operational (Kwajalein)

ALTAIR 24/7 SPACETRACK

Operational

GaAs Ka-band Transmit/Receive

Module

Tunable Solid-State Laser Developed

Lightweight Steering Mirror Fabricated

Ultraviolet and Visible Angle-Angle-Range

Laser Radar Developed

Optical Beam-Steering System Developed

Thermal Blooming Correction of MIRCL

Laser (SABLE)

Wideband Laser Radar (Firepond)

Semiconductor, Diode-pumped, Q-Switched Nd:YAG Transmitter

(Firepond)

MMW Beam-Waveguide System

32 � 32 Geiger Mode Avalanche Photodiode

Angle-Angle-Range Laser Radar

Cobra Gemini Operational

Kwajalein Modernization and Remoting (KMAR)

KMAR Radars Operational

Cobra Judy II Support

THAAD Radar Conversion to TPS-X

Compact LADAR Range

Avalanche Photodiodes

Cobra Eye Sensor Operational

(Shemya AFB, AK)

Schottky-Barrier PtSl Detectors

Cobra eye Sensor in “Hot Storage”

Micro-lens Focal Plane Array

Sea Lite Beam Director (SLBD) (WSMR)

Fly-Along Sensor Package (FASP) Flown on

TCMP-2A

Termination of Cobra Eye

Seeker Experimental System (LL)

Space-Based Visible Sensor (MSX)

Captive Carry (IR Seeker)

Discrimination Performance

(k-factors)

Atmospheric Compensation

Experiments-CLASP, TRAPAF, OCULAR (FL)

Have Sled Tests (Alaska)

Sky Noise Measurements NASA Lear Jet

(CA, AK, Panama)

Atmospheric Transmission

Measurements NASA Lear Jet

Atmospheric Compensation

Experiments-ACE, SWAT (HI)

Lexington Discrimination System (LDS)

Kwajalein Discrimination System (KDS)

Real-Time 2-D Radar Imaging

Atmospheric Compensation Experiments-

LACE, SABLE, Firepond (CA, MA)

Firefly Tests (Wallops Island)

Firebird Tests (Wallops Island)

TCMP-1 Tests (Kwajalein)

Simulation of ABL Propagation Effects

(Firepond)


Red Crow Test (Hawaii)


Ballistic Missile Defense System

Testbed

3-Band IR Discrimination

Technique

Phase-Derived Range Applied to Target

Dynamics

Space-Based IR Calibration

Coherent Polarization Techniques

Bandwidth Interpolation

Multi-Aspect Imaging

THAAD Analysis Workstation

Measurements-Based Target Modeling

Cobra Dane Radar Operational

Safeguard System Deactivated

Site Defense

“Strategic Defense” Speech by Pres.Reagan

Defensive Technologies Study

Formation of SDIO

Cobra Judy Radar Operational

Homing Overlay Experiment (HOE) ICBM

Hit-to-Kill

Global Protection Against Limited Strikes

(GPALS)

Persian Gulf War

Theater Missile Defense (TMD)

Dissolution of USSR

START I Treaty

SDIO to BMDO

National Missile Defense (NMD)

First Successful NMD Intercepts

First Successful TMD Intercepts

BMDO Reorganized to MDA

Integrated BMD System (BMDS)

Navy Theater Wide System Terminated

Non-nuclear Interceptor

MDS-3 Study

Strategic Defense Concept Study

LWIR Exoatmospheric Discrimination

Optical Discrimination Study

Pilot Architecture Study

Interactive Discrimination

Radar Discrimination Study

MATTR Study

Mid-Course Sensor Study

Theater Defense Netting Study

Navy TMD

National Missile Defense (NMD)

Navy Radar Roadmap

IR Seeker Band Selection Study

Discrimination Technology Roadmap

Pan Pacific Range Roadmap

Sensor Fusion Study

Sea-Based Terminal Study



By 1992, the USSR had collapsed, USSR and U.S.strategic missile arsenals were reduced under StrategicArms Reduction Treaties (START 1 and START 2),and theater missile proliferations were underway. TheScud missile, a derivative of the World War II Ger-man V-2s, which had been further developed by theSoviets, had become the only ballistic missile used ex-tensively after World War II. Scud was used duringthe Middle East War of 1973, later in large numbersduring the War of the Cities between Iran and Iraq,and extensively during the Persian Gulf War in 1991.As a result, the BMD effort in the United States wasredirected to deal with more limited threats againstthe territory of our nation and our allies and againstdeployed troops involved in theater engagements.The SDIO was renamed the BMD Organization(BMDO). The discrimination problem, although notfully solved, became more tractable. The ICBMthreat was more limited in numbers, and technologyhad surged ahead during the SDI years. Short-rangemissiles used in theater engagements generally do notcarry light decoys. But challenges in theater defenseremain. Short timelines and the need to defend si-multaneously against air-breathing threats (cruisemissiles) makes theater missile defense difficult evenagainst short-range missiles.

In January 2002, the BMDO was redesignated theMissile Defense Agency (MDA) and given the task ofdeveloping a single integrated Ballistic Missile De-fense System (BMDS).

Current BMD technology provides powerful high-frequency wideband phased-array radars, infrared(IR) seekers, light non-nuclear hit-to-kill intercep-tors, and fast computers. A tool kit of discriminationalgorithms, under development since the 1960s, nowexists. The challenge for discrimination is to designan architecture of discrimination algorithms that issufficiently flexible and resilient to deal with evolvingthreats and countermeasures. With the advent of hit-to-kill interceptors, end-game discrimination is alsoneeded. Discrimination information from a ground-based radar and from space-based IR sensors must behanded over to the interceptor seeker in a form it caninterpret and fuse with its own discrimination data.The interceptor seeker must aim at a specific hit pointon the missile in order to destroy it, and the ground-

based radar and space-based IR sensors must assessthe effectiveness of the intercept. Because there arestill no absolute methods for ensuring good discrimi-nation against all threats, the collection and analysisof performance data during combat to identify dis-crimination modifications quickly is also needed.

Early Laboratory Work in BallisticMissile Defense (1958–1972)

The ARPA program in BMD technology was cen-tered in Project Defender and was focused on one ofthe most challenging problems in BMD, namely, dis-criminating warheads from decoys and deploymenthardware. ARPA turned to Lincoln Laboratory andbegan sponsoring work in discrimination in July1958, an effort that has continued to the present, al-though under different sponsors [9]. The BMD pro-gram at the Laboratory grew to include developmentof radar and IR sensors capable of making flight-testmeasurements, which led to the formulation of dis-crimination algorithms, the planning and executionof flight tests, the development of sensor technologiesappropriate for BMD systems, and the design, analy-sis, and performance evaluation of candidate BMDsystems. The following section summarizes key re-search areas in BMD during this period.

Phenomenology and Discrimination

The ability to discriminate a warhead from accompa-nying decoys or deployment hardware depends onhow closely the signatures of these objects match thatof the warhead and how well the observing sensorscan detect the dissimilarities. In the early period,when the sensors had relatively crude performance(e.g., poor resolution), discrimination was difficult. Itwas especially difficult at high altitudes, where atmo-spheric interactions with the incoming objects arenonexistent. At lower altitudes, where atmosphericinteractions exist, discrimination becomes less diffi-cult for two reasons. First, many objects (especiallythe deployment hardware and the more poorly de-signed decoys) are slowed by the atmosphere with re-spect to the warhead and thus are naturally filteredout. Second, objects reentering the atmosphere createa plasma bow shock and a wake of ionized gas that isdetectable by a radar. The magnitude of these returns



is related to the energy of the incoming object andhence to its mass, thus providing a basis for discrimi-nation.

Several field-test programs were initiated to makephenomenology measurements relating to the effectsdescribed above, and then to develop discriminationtechniques and algorithms. The programs and sensorsused for these measurements are described below.

Measurements at Arbuckle Neck,Wallops Island, Virginia

The initial set of field measurements (from March1959 to July 1962) was made in a joint program withthe National Aeronautics and Space Administration(NASA), during which launches from Wallops Island,Virginia, of the NASA Trailblazer I vehicle were ob-served. Fourteen launches occurred during this forty-month period. By using a total of six stages, three ofwhich fired during descent, the Trailblazer I was ableto boost 2-lb payloads to ICBM velocities. Later(1962 to 1965), the Trailblazer II had a payload capa-bility of 35 lb. Three radars were built by LincolnLaboratory and installed at Arbuckle Neck for thesetests. The first radar, an S-band tracker with a 60-ftdish, successfully tracked the first Trailblazer launchin December 1959. The second radar, also with a 60-ft dish, had duplex UHF and X-band systems thatwere slaved to the S-band tracker to form the first in-tegrated multiwavelength data-gathering systems formissile observations. The third radar of the trio wasthe Space Range Radar, or SPANDAR (built forNASA), another S-band system with a superiormount designed expressly for tracking satellite androcket vehicles at long ranges. Observations of thesmall Trailblazer payloads by the three radars led toincreased understanding of the wake properties of re-entering vehicles; however, the understanding waslimited because of the poor resolution of the radarsand the small size of the payloads.

Reentry Simulation Range

To supplement the phenomenology measurements atWallops Island, the Laboratory constructed a ReentrySimulation Range (RSR) in 1960. The range in-cluded a powder gun that fired half-inch projectileswith a speed of 9.2 kft/sec, and a light-gas gun that

fired 0.186-in projectiles with a speed of 20 kft/sec[9]. Optical and microwave sensors and schlierencameras were used to make measurements. The RSR,which operated until 1970, provided insight on thereentry effects associated with an object entering theatmosphere at high speed.

White Sands Missile Range

Other tests were conducted at the White Sands Mis-sile Range (WSMR) in New Mexico. The tests usedthe ARPA Measurements Radar (AMRAD), an L-band 60-ft dish radar built for Lincoln by Raytheon,to observe the reentry (at WSMR) of Athena missileslaunched from Green River, Utah, and acceleratedduring their late flight. AMRAD used burst wave-forms to achieve the high Doppler ambiguitiesneeded for measuring velocities of ionized gases in thewake.

Project PRESS

The largest program supported by ARPA to investi-gate discrimination was Project Pacific Range Electro-magnetic Signature Studies (PRESS), which began inmid-1958, with Lincoln Laboratory as its technicaldirector. Central to PRESS was the construction ofseveral large instrumentation radars to make measure-ments during field tests for developing and validatingdiscrimination algorithms. Under ARPA sponsor-ship, three such radars were constructed (describedbelow). Also constructed under PRESS were airbornepassive optical sensors carried in a KC-135, and nu-merous ground-based optical sensors interconnectedthrough and controlled by an IBM 7094 computer.

TRADEX. The Target Resolution and Discrimina-tion Experiment (TRADEX) radar was a derivative ofthe UHF surveillance and tracking radar that RCAhad built for the Ballistic Missile Early Warning Sys-tem, but with an added L-band tracker and data-gathering capability. When in February 1959 theArmy decided to locate its Nike-Zeus anti-ballisticmissile system at Kwajalein (where it could operateagainst targets launched from Johnson Island in thePacific Ocean or from Vandenberg Air Force Base inCalifornia), it became evident that TRADEX shouldbe located at the same atoll. A site on the island ofRoi-Namur at the northern end of Kwajalein Atoll



was selected, and construction of TRADEX began in1961. (The site is now called the Kiernan ReentryMeasurements Site [KREMS] in honor of Lt. Col.Joseph Kiernan, U.S. Army, who played an importantrole in the site selection process and who was laterkilled in action in Vietnam.) On 26 June 1962,TRADEX successfully tracked the first Atlas ICBMlaunched to Kwajalein, which led to its acceptance byARPA and subsequent transfer to Lincoln Laboratoryon 1 December 1962. Since then, TRADEX hasgathered valuable data on the discrimination of mis-sile warheads.

ALTAIR. In the early 1960s, the United States dis-covered that the Soviet Union was developing verylarge VHF and UHF phased-array radars (dubbedDoghouse and Henhouse) for ballistic missile detec-tion and defense. Understanding how U.S. missileswould fare against these radars required testing themagainst radars of similar frequency and capability.Hence the second PRESS radar was initiated: theARPA Long Range Tracking and InstrumentationRadar (ALTAIR). Sylvania Corporation won the con-tract to build ALTAIR, which was specified to be ahigh-sensitivity VHF tracker, incorporating a UHFtransmitter/receiver to provide data with superiorsensitivity and range resolution than that availablefrom TRADEX. ALTAIR’s antenna is unusual for itssize and agility: it is a 150-ft dish capable of accelera-tions of 2∞/sec2 and angular rates of 10∞/sec. The ro-tating components of the antenna weigh 800 klb.Since becoming operational in May 1970, ALTAIRhas supplied much valuable data that has contributedgreatly to the development of discrimination tech-niques.

ALCOR. In this same period, Lincoln Laboratoryengineers began to examine the use of widebandwaveforms for discrimination of warheads from de-coys on the basis of their physical dimensions [10].While it is possible in a test range to employ low-power short pulses to measure the length of a statictarget, it is not possible to pack enough energy in ashort pulse to make similar measurements at ranges ofseveral hundred kilometers, as would be required by aBMD radar. Nor was it known how the plasmasheath that forms around a body in reentry would af-fect such measurements. The Laboratory used pulse-

compression techniques to modulate the frequency oflong radar pulses over a wide frequency band andthen upon reception to compress the return signal, ef-fectively integrating the received energy into a veryshort pulse [10]. In response to a Laboratory proposaldated 17 June 1965, ARPA authorized the Labora-tory to build the ARPA/Lincoln C-band ObservablesRadar (ALCOR) at Kwajalein. Lincoln Laboratorywas the prime contractor, and utilized subcontractorssuch as Hughes, Honeywell, Westinghouse, andRCA. ALCOR became operational in January 1970.

Passive Optical Sensors. The major passive opticalsensors for PRESS were those carried aboard the AirForce KC-135 aircraft. The initial instrument (calledSkyscraper) was an IR tracker/spectrometer devel-oped by the Geophysics Research Directorate of theAir Force Cambridge Research Laboratory. This in-strument was soon augmented with seven others.Data gathering on missile flights to Kwajalein com-menced in 1964. During the course of the next fewyears several of these instruments were replaced. TheSkyscraper was replaced by a new tracker/spectrom-eter called the Airborne InfraRed Telescope (AIRT).Operations continued until 1972 when the use of theKC-135 was ended.

For a brief period (1964 to 1966) some passive op-tical instruments were also carried aboard a NavyA3D aircraft. There were also ground-based instru-ments, including ballistic cameras, a spectrograph,and a Recording Optical Tracking Instrument(ROTI) located at various islands of the KwajaleinAtoll.

Phased Arrays

It was recognized early on that the traffic-handlingcapacity of the early BMD radar sensors was limitedby the mechanical movement of their dishes. A muchfaster and more agile way of controlling the propagat-ing direction of a radar beam was by using a set offixed radiating elements, the relative phases of whichwere controlled to form a beam in a chosen direction.Such electronic movement of the beam could be ac-complished in microseconds, in contrast to the me-chanical slewing of a dish, in which response times aremeasured in seconds.

In the late 1950s Laboratory staff began an intense



program in phased-array technology. Array theorywas investigated, beamforming and beam-scanningschemes were analyzed, and several test arrays werebuilt [11]. Collaborations with a wide range of indus-trial and government development programs wereestablished. In later years the Laboratory made im-portant contributions to phase shifters, solid statetransmit/receive modules, gallium-arsenide mono-lithic microwave integrated circuits, and array calibra-tion and testing [11].

The following example describes Lincoln Labora-tory’s work in phased shifters. For a phased-array ra-dar to perform beam steering, it is essential that thephases of each contributing radiating element be pre-cisely controlled, because the accuracy of the phasesdetermines the shape and quality of the resultingbeam. In the 1960s and early 1970s, Lincoln Labora-tory developed latching ferrite phase shifters, whichhave since become standard configurations for indus-try. These devices produce phase shifts of a microwavesignal through interaction with a magnetized ferrite.Lincoln also researched and developed suitable ferritematerial, because the materials available at the timewere expensive and incapable of maintaining a con-trolled magnetic state over a range of ambient tem-peratures and stresses. Appropriate low-cost ferritematerials with superior operating characteristics weredeveloped at the Laboratory in the early 1970s.

Countermeasures

In 1962, under Air Force sponsorship, the Laboratorybegan work on the design, development, testing, andevaluation of countermeasures. The objective of theprogram (named Advanced Ballistic Missile ReentrySystems, or ABRES) was to examine the effectivenessof various U.S. countermeasures against postulatedSoviet BMD systems. Work of this nature continuesat the Laboratory, but this article does not go into de-tails. We note that during this period several counter-measure devices were fabricated and tested at LincolnLaboratory. Among them were the first inflatable rep-lica decoys and compact radar jammers.

Operational Strategic Missiles

The Laboratory has also been involved since the late1960s in examining the effectiveness of Air Force and

Navy strategic missiles. To that end, measurements ofoperational ICBMs impacting in the vicinity ofKwajalein Atoll were analyzed. Studies at differentlevels of complexity have contributed to the determi-nation of the effectiveness of these missiles for differ-ent offense-defense scenarios. As with the case of theABRES program, we do not treat this topic further inthis article.

It is worth remarking, however, that the Labora-tory’s BMD expertise coupled with its involvement inthe ABRES program and strategic-missile effective-ness work enables the Laboratory to view both sidesof a complex offense-defense interaction, in whichthe offense develops and tests countermeasures andthe defense develops systems to counter them.

Key Developments of the Early Years

During the early period from 1958 to 1972, the per-formance of BMD radars improved significantly.Phased arrays were developed to improve traffic han-dling. Pulse-compression waveforms, with improvedrange resolution, were demonstrated. A library of co-herent radar waveforms was built to measure the ion-ized wake of objects in reentry. By the end of the pe-riod, an extensive database of high-quality radarsignature data had been assembled on the plasma bowshock and wake of warhead-like targets. This infor-mation was used for developing discriminants for de-fense systems designed during the subsequent middleperiod, from 1972 to 1983.

The Middle Period (1972–1983)

In 1972, the United States and the Soviet Unionsigned the ABM Treaty, which limited the deploy-ment of BMD systems to 100 interceptors located ata single site. However, the treaty allowed continuedresearch and development in BMD. In the UnitedStates, that research focused on systems to defendMinuteman (MM) and Peacekeeper (MX) missiles intheir silos or in a different basing mode. Experts feltthat low-leakage defense of a city against a massiveSoviet first strike was not possible, and that only thethreat of massive retaliation would deter such an at-tack. That retaliation depended on the survival ofsome fraction (roughly, one-third, in some estimates)of our MM and MX missile force. The putative stra-



tegic balance achieved by assuring the survival of thisfraction was called mutual assured destruction(MAD).

The first BMD systems defined in this period,Sentinel and Safeguard, were based on componentsoriginally developed for urban defense. The radars forthese systems were expensive, and both the radars andthe urban targets were vulnerable to nuclear attacks.The MM and MX silos, on the other hand, weremuch harder than cities, allowing the intercepts to beconducted at much lower altitudes and the radars tooperate at shorter ranges, and thus be less vulnerableto nuclear attacks and penaids. The silo-defense sys-tems envisioned were named Site Defense and laterSentry, neither of which was deployed.

During this period, Lincoln Laboratory’s researchefforts expanded to include a number of areas, whichare described below.

Discrimination

The discrimination requirements for dedicated silodefense systems differed significantly from those forurban defense considered in the early period ofBMD. Since the Site Defense and Sentry radars oper-ated at relatively short ranges and had to be hardenedagainst nuclear effects, the defense battlespace shiftedto lower altitudes than for Nike X, Sentinel, or Safe-guard. Against a massive attack with sophisticatedwarheads and penaids, the defense would rely on theatmosphere to filter out much of the missile debrisand light decoys, leaving only the warheads and heavyreentry decoys to be discriminated.

Early in the development cycle, measurements ofbooster-tank breakup in reentry indicated that largenumbers of fast booster-tank fragments must be an-ticipated in the Site Defense radar battlespace. It wasrecognized that some technique of bulk filtering wasneeded to discriminate these fragments. Special burstwaveforms were proposed to separate warheads anddecoys from the slightly slower fragments located atthe same range. Once warheads and decoys were de-tected among the fragment set, it was necessary todiscriminate them. New discriminants were pro-posed, based on very fine range resolution, such as anestimate of target length or wake-velocity measure-ments at low altitudes.

Radar Development

New burst or pulse-pair waveforms were developedand installed on the radars at Kwajalein to measurethe aerodynamic structure of the wake. New discrimi-nants based on fine range resolution were achievedwith the wideband waveforms of ALCOR. Concur-rently, considerable work was done on the develop-ment of signal processors and signal processing tech-niques to bulk-filter the many fragments in thevicinity of the warhead with the use of minimal radarresources.

Radar Modifications at Kwajalein

The new waveforms and signal processing techniquesresulted in, and depended upon, several modifica-tions of the Kwajalein radars, exemplifying three ma-jor themes: (1) modification of radars with widebandwaveforms, (2) software development of discrimina-tion algorithms, including their real-time testing, and(3) development of a millimeter wave (MMW) radarto obtain data for interceptor seekers. These modifi-cations are discussed below.

ALCOR. Simple tracking radars can collect metricdata (that is, determine the location and trajectory ofa target) but can do little in the way of processing sig-nature data (for example, determine target size orshape). Interest in wideband measurements resultedfrom the need to reject small decoys that might beotherwise credible targets (that is, they might havecredible slowdown and present warhead-like radarcross section [RCS] levels to a narrowband radar).Initial work on wideband radars focused on the hard-ware required to generate and process high-resolutionwaveforms [10]. Initial tests of ALCOR in the 1970sshowed that length measurements were feasible andcould provide important discrimination informationagainst penaids such as small decoys. Later in this pe-riod, Laboratory staff developed and installed surfaceacoustic wave (SAW) devices for pulse compression.

TRADEX. In the late 1970s, TRADEX was shutdown for a major redesign. The UHF capability wasremoved. A new feed and additional channels wereadded to make it an L-band tracker, and an S-bandradar was added, which complemented a phased-ar-ray Site Defense radar built at Kwajalein. The phased



array could make measurements over a very largethreat cloud, but it lacked the sensitivity and mea-surement precision of TRADEX. Thus these two ra-dars were combined to gather a database of measure-ments for developing discrimination algorithms.

Real-Time Testing of Discrimination Algorithms. Bythe late 1960s, considerable data had been collectedby the TRADEX radar, on the basis of which severaldiscrimination algorithms had been developed. Theconventional manner of developing a discriminationalgorithm was to analyze a large set of field data, thento postulate an algorithm that could be tested at lei-sure on other collected data. This process was timeconsuming and depended on the insights of indi-vidual scientists. Furthermore, this approach did notdisclose the practical difficulties that would arisewhen the algorithm was implemented in a realisticenvironment in the field. One of the pioneering ef-forts of the Laboratory was to develop techniques forconverting a candidate algorithm to a detailed soft-ware program that would accept radar data at real-time rates and output a decision, or sequence of deci-sions, concerning the nature of the target. Integrationof such an algorithm into an overall logic (or schema)that realistically simulates the conditions of a radar inthe field is an essential step in selecting algorithmsthat will work not only in the laboratory but also inpractice.

In 1969, after ARPA had relinquished its role inBMD to the Army, the Army Ballistic Missile De-fense Agency (ABMDA) requested the Laboratory in-stall a real-time discrimination schema on the Kwaja-lein radars, to be used as a model for such systems asSafeguard and Site Defense. The implementation,which was termed the Reentry Designation and Dis-crimination System (REDD), became operational in1972.

TRADEX was the first radar incorporated intoREDD, which was based on a CDC 6600 computer.An identical computer with identical software was in-stalled at Lexington, where algorithms were devel-oped and tested on recorded radar data. The promis-ing algorithms were then demonstrated in real timeon actual missile flights into Kwajalein. In this man-ner, a number of tracking and wake discriminantswere fully tested.

Shortly after its initial operational date, ALCORwas incorporated into REDD for real-time testing ofvarious length-measurement algorithms for the SiteDefense system. Although ALCOR operates at C-band and Site Defense at S-band, the algorithms de-veloped on ALCOR data worked well when they wereimplemented on the Site Defense radar. A number ofbulk filtering algorithms were developed and partiallytested by using TRADEX data modified so as to re-semble data collected by a phased-array radar.

ALTAIR. Initially, ALTAIR tracked at VHF andpassively collected data at UHF. Because the Perim-eter Acquisition Radar (PAR) of the Safeguard systemoperated at UHF, however, this part of ALTAIR wasmodified to represent the PAR. Actual PAR algo-rithms were tested during Safeguard flights and be-came a major element of the REDD system. (Afterthe termination of the Safeguard system, the PAR wastransferred to the Air Force to be used for surveillanceand threat warning.) The Simulation of PAR(SIMPAR) involved running the PAR real-time pro-gram on the CDC 6600 at Kwajalein, modifying theALTAIR feed to permit monopulse tracking at UHF,and adding new waveforms to simulate narrowbandPAR waveforms. The new feed included a frequency-selective subreflector almost 7 m in diameter. Themodified radar operated well; the PAR software pro-duced good results, and the modifications were in-valuable for future ALTAIR operations.

Millimeter-Wave Radar. Late in the 1970s, interestarose in using MMW seekers for homing intercep-tors, such as the Patriot Advanced Capability (PAC-3), and in using MMW radars for airborne or spaceapplications to detect and discriminate targets athigher altitudes. In general, millimeter waves are at-tractive when the antenna size is limited by platformconstraints. Lincoln Laboratory proposed to theArmy that a MMW radar be constructed at Kwajaleinto make measurements relevant to these interests.With Army approval, the radar was constructed; itachieved operational status in the early 1980s. TheMMW radar has a 14-m dish and operates at 35 and94 GHz. Interpolation between its lower frequencyand ALCOR (at 5 GHz) provides a good approxima-tion to what a current defense radar at X-band (10GHz) might measure.



Flight Tests

The Laboratory also conducted several flight tests(Have Jeep, Have Sled) with sounding rockets duringthis period to collect data for discrimination algo-rithm development. For a detailed account of thesetests, see the article by Kent R. Edwards and Wade M.Kornegay, entitled “Measurements, Phenomenology,and Discrimination.”

Infrared Sensors

In the late 1970s, there was increasing interest in theuse of passive IR sensors for discrimination. Calcula-tions suggested that the temperature of thermallyuninsulated black and gray bodies would depend ontheir mass. Therefore, multicolor IR sensors might beuseful in exoatmospheric discrimination. A detailedstudy carried out by the Laboratory resulted in thedesign, development, and construction of the CobraEye aircraft described in the final section of this ar-ticle, and in an accompanying article in this issue byBartley L. Cardon, Donald E. Lencioni, and WilliamW. Camp, entitled “The Optical Aircraft Measure-ments Program and Cobra Eye. “

Army Optical Station

With the focus of the U.S. BMD effort shifting to thedefense of hard targets, measurements made duringmissile reentry became important. Because the air-borne optics program was terminated in 1972, therewas a need for expanded ground-based optics. TheLaboratory proposed the creation of an Army OpticalStation (AOS) at Roi-Namur Island in the KwajaleinAtoll. The AOS consisted of two passive IR sensorand a laser radar.

The passive IR sensors (SAMSO/Lincoln Trackingand Acquisition Infrared Experiment [SOLITAIRE]and Ground Based Measurement [GBM]) were origi-nally located at White Sands Missile Range and wereboth originally developed and operated for measure-ments there. Each was extensively reworked (SOLI-TAIRE by the Laboratory and GBM by General Elec-tric) and installed in the AOS. Operations began in1973 for SOLITAIRE and in 1976 for GBM. TheLaser Infrared Tracking Experiment (LITE) was aneodymium-doped yttrium aluminum garnet

(Nd:YAG) laser operating at a wavelength of 1.064mm. LITE began operations at Kwajalein in 1977.

BMD Analyses and Studies

As Soviet ICBM force levels and circular error prob-abilities (CEPs) improved (primarily, through the useof multiple independently targeted reentry-vehicle[MIRV] technology, which increased the numbers ofindependently targeted warheads per missile, andthrough the use of bussing, which improved their im-pact accuracy), it was expected that improved BMDwould be required to maintain survivability of the de-terrent force. Several national studies were conductedduring this period to investigate and evaluate the per-formance of BMD systems proposed for the defenseof MM and MX. Lincoln Laboratory staff played ma-jor roles in these studies.

Foreign Missile Data Collection and Interpretation

In the 1970s, radars began collecting foreign-missiledata, which was subsequently interpreted. The pri-mary collection radars were the Cobra Dane radarand the radars of the Cobra Judy ship [10]. LincolnLaboratory was consulted in the design of these radars(both built by Raytheon Corporation), and played arole in reduction and analysis of the data. The infor-mation gained was of great use in the design of BMDsystems. The Laboratory later developed the CobraGemini shipboard collection system to gather intelli-gence on shorter-range missiles.

Thermal-Blooming Experiments

The transmission of a laser beam through the earth’satmosphere broadens the beam and degrades its co-herence, a phenomenon known as thermal blooming.The general technique for correcting this effect is tomeasure the gradient of the phase error of thewavefront from a known source and use that informa-tion to reconfigure the surface of a deformable mirror.In the 1960s the Laboratory began the developmentof the hardware and conducted measurement pro-grams to verify this technique. These efforts extendedwell into future eras.

Key Developments of the Middle Period

The period from 1972 to 1983 saw impressive ad-



vances in the use of radars for BMD discrimination.Phased array radars were deployed, among them theMissile Site Radar and Site Defense radars atKwajalein, and the PAR in North Dakota. The firstwideband radar (ALCOR) sited at Kwajalein madeimportant measurements on ICBMs. Many discrimi-nation algorithms were developed, some of thembased on wideband measurements that achieved highresolution. Schemas were designed, implemented atKwajalein, and tested in real time. These advanceswere preludes to the needs of BMD during the subse-quent periods from 1983 to the present. As a result ofthese efforts, a large body of knowledge on the perfor-mance of radars for BMD discrimination existed atthe beginning of the SDI era in 1983.

The SDI Era (1983–1993)

The SDI era of ballistic missile defense began as a re-sult of President Reagan’s speech to the nation on 23March 1983. In this speech, the President questionedwhether the strategic doctrine of mutual assured de-struction could produce lasting stability. He arguedthat effective ballistic missile defense would allow“free people to live secure in the knowledge that theirsecurity did not rest on the threat of instant U.S. re-taliation to defer a Soviet attack.”

Following his speech, the President ordered thattwo studies be conducted. The first of these was di-rected to examine the feasibility and technology re-quired to conduct effective defense against massiveICBM attacks. The second was to examine strategicand arms-control policy implications. Both studieswere conducted in the summer and early fall of 1983.

The technology study, called the Defensive Tech-nologies Study (DTS), was headed by James Fletcher,a former NASA director, and involved approximatelyforty experts in BMD systems and in BMD technol-ogy. Several Lincoln Laboratory staff members servedon this study and contributed to the DTS conclu-sions and recommendations.

The DTS resulted in two major recommendations.1. A multilayer defense should be used to achieve

low leakage. For example, a three-layer defense,each layer independent of the others and with aleakage of 10% per layer, could achieve an over-all leakage of 0.1%. Figure 6 shows a genericsketch of an ICBM trajectory with possible lay-ers and associated timelines.

2. To complicate the design and use of counter-measures, several different types of sensors (mi-crowave radars, lasers, passive IR sensors)should be employed for detection, tracking, and

FIGURE 6. Ballistic missile timeline for a nominal intercontinental ballistic missile (ICBM) flight. The trajectory is divided intofour phases: boost, deployment, midcourse, and terminal. Under the Defensive Technologies Study (DTS) multilayer defenseplan, sensors would detect, track, and discriminate, and interceptors would attack during each of the four phases.

Boost3–5 min

Deployment0–5 minMidcourse

10–15 min

Terminal 2–3 min



discrimination. In addition, a variety of inter-ceptors (e.g., kinetic energy interceptors, lasers,neutral particle beams) should be used to maxi-mize the probability of warhead kill.Not all the technologies required for implement-

ing a multilayered BMD were available. In some casesthere were competing technologies and the DTScould not select the one most likely to succeed. How-ever, the DTS concluded that “powerful new tech-nologies are becoming available that justify a majortechnological development effort offering futuretechnological options to implement a defensive strat-egy.” The DTS then recommended a long-term re-search and development effort that would select themost promising technologies, which in turn would bethe basis for future BMD architectures.

To implement the research and development pro-gram recommended by the DTS, the SDIO was es-tablished in January 1984 with Lt. Gen. JamesAbrahamson of the Air Force as the director. LincolnLaboratory’s efforts during this period are summa-rized below.

Technology Studies

The SDIO moved quickly and vigorously to initiateresearch programs in all the areas the DTS recom-mended. This was accomplished by conducting de-tailed studies in specific areas to investigate particulartechnologies in detail. The Laboratory was the leadorganization for these investigations, directing fourcrucial studies in the 1980s that were instrumental inguiding SDIO research in BMD sensors. These stud-ies were:1. The Optical Discrimination Study (1984) ex-

amined the capabilities of passive IR sensors todiscriminate countermeasures from warheadsand made recommendations on IR sensor devel-opment.

2. The Radar Discrimination Study (1985) exam-ined the capabilities of microwave radars to dis-criminate countermeasures from warheads andmade recommendation on microwave radar de-velopment.

3. The Interactive Discrimination Study (1986)investigated the performance of interactive dis-crimination (disturbing ICBM components

and measuring the effects of the disturbance),and described the sensors required for this typeof discrimination.

4. The Midcourse Sensors Study (1988) did acost-effective analysis of space-based IR sensorsthat detected, tracked and discriminated ICBMelements.

Research Development Highlights

As these studies progressed, SDIO was quick to beginresearch developments along the recommended lines.The Laboratory had significant involvement in thefollowing research efforts.

Exoatmospheric Discrimination. The exoatmo-sphere is the most difficult phase for successful dis-crimination. Here there is no atmosphere to slowdown or to impart particular signatures to decoys.Reliance must be placed on “birth-to-death” trackingschemes, on small motion differences, and on thermalsignatures measured by IR sensors. The Laboratoryconducted research in all these areas, focusing on thecapabilities and limits of optical discrimination in-cluding analyzing data gathered by passive IR sensorsand lasers on flight tests at Wallops Island, Virginia.

Development of Optical Sensors. Following the rec-ommendations of the Optical Discrimination Study,an extensive program was carried out to develop pas-sive IR sensors and lasers for discrimination. Of greatinterest was the development of several laser “phasedarray” techniques that allowed many bodies to betracked near simultaneously. Discrimination algo-rithms based on passive IR and laser-radar data weredeveloped, and several field tests were conducted.

Constructing and Operating Optical MeasurementSensors. The Laboratory constructed optical measure-ment sensors to make the measurements necessary fordeveloping optical discrimination. The AOS as-sembled at Kwajalein consisted of two passive IR sen-sors and a doubled-frequency Nd:YAG laser.

A large-scale (60 cm diameter) IR telescope wasdesigned, built, and installed on a modified KC-135aircraft. The Cobra Eye IR sensor was used for thecollection of both foreign and domestic missile tests.

Modifications to the Kwajalein Radars. The Kwaja-lein radars were modified with waveforms and signalprocessors that simulated radars that eventually



would be used as BMD operational radars. Of greaterimportance, the Kwajalein radars were netted to-gether, thus allowing for improved operation and amore effective simulation of netting the operationalBMD radars.

Lexington and Kwajalein Discrimination Systems.Large-scale simulations were constructed to allow thetesting of individual discrimination algorithms and ofcombinations of discrimination algorithms. Therewere duplicate systems, one at Lexington and one atKwajalein.

Other Technology Efforts. Several other technologyefforts important to BMD were pursued. These in-cluded development of monolithic 35-GHz trans-ceivers, electro-optic switches, and analog-to-digitalconverters.

Architectural Studies

There were two major architectural studies in the1980s with extensive Laboratory involvement:

Pilot Architecture Study. In the fall of 1984, SDIOsponsored the Pilot Architecture Study (PAS). Themembers of this study were drawn from various Fed-erally Funded Research and Development Centers(FFRDCs), the government, and the military. ThePAS defined a baseline multi-tier defense-system ar-chitecture to counter a massive ICBM attack from the

Soviet Union. The PAS concluded that rocket-based-technology weapons could be developed morequickly than directed-energy systems. Consequently,the concept of an evolutionary architecture wasadopted by the SDIO. Figure 7 shows a notionalchart depicting the planned evolution of BMD [13].

Mid- and Terminal-Tier Review. A comprehensivereview (in which Lincoln Laboratory staff memberstook a leading role) of the expected capabilities andcost of the Phase I system was concluded in the sum-mer and fall of 1990. Called the Mid- and Terminal-Tier Review (MATTR), the study concluded thatsmall space-based interceptors as well as space-basedsensors would be needed to augment ground-basedinterceptors and radars to counter a massive (over3000 warheads) attack on the United States.

Key Developments of the SDI Era

Toward the end of the SDI Era, two major events oc-curred that changed the direction of BMD efforts.The first was the collapse of the Soviet Union in De-cember 1991. The second was the theater ballisticmissile attacks launched by Iraq upon U.S. and alliedforces as well as upon Israel during Desert Storm, theGulf War in 1990 [13]. The main threat changedfrom a massive ICBM attack upon the U.S. mainlandfrom the Soviet Union to a limited attack from any ofseveral countries [14] and to a theater attack uponU.S. and allied expeditionary forces. The shift in di-rection was made explicit by the Missile Defense Actpassed by Congress in 1991. The act directed the Pen-tagon to develop and deploy theater BMD systems,which included participation by the Army, Air Force,and Navy. It also directed the Pentagon to pursue thedevelopment of an ABM-treaty-compliant nationalmissile defense (NMD). In 1994, the NMD Programwas redirected to a technology-readiness program[13].

The SDI Era was characterized by the following:1. Technologies required for NMD were explored

and selected, and development was initiated.2. Architectural evolutions of an NMD system to

counter a large scale attack upon the UnitedStates were defined.

3. The threat was shifted from that of a massive at-tack upon the United States from the Soviet

FIGURE 7. The architecture plan toward “thoroughly reli-able” defenses. The plan envisions a BMD system of in-creasing capability. Initially the system elements are radars,infrared sensors, and kinetic energy interceptors. Laser di-rected-energy interceptors and advanced discriminationsensors are added.

Capability

Development and deployment decision

Phase II

Phase III

Phase I

Advanced directed energy Weapons and support technologies

Directed energy systems Active discrimination sensors

Kinetic energy interceptors, radars and passive sensors

Time



Union to a limited attack initiated by any ofseveral countries on the United States and alliedexpeditionary forces.

4. The NMD effort was redirected to a technol-ogy-readiness program.

5. A major effort involving all military services wasbegun to develop and deploy TMD systems.

The BMDO/MDA Era (1993 to Present)

By 1993 there was a major redefinition of the goals ofBMD and a consequent restructuring of the program.The new goals were to (1) place primary emphasis onthe development and acquisition of Theater MissileDefense (TMD) for the protection of expeditionaryforces, and (2) restructure NMD to a technology-readiness program [13]. Consequently, the programoffice was restructured and its name was changedfrom the SDIO to the BMDO. Funding for researchefforts was reduced to achieve these goals.

In January 2002, the Secretary of Defense redesig-nated the BMDO as the Missile Defense Agency(MDA) and directed the establishment of “… a singleprogram to develop an integrated system….” Therole of that system, to be called the Ballistic MissileDefense System (BMDS), was “to intercept missilesin all phases of their flight, against all ranges ofthreats.”

Theater Missile Defense

Because ballistic missile attacks upon expeditionaryforces can occur in a variety of geographic locations,no one armed service can develop a TMD system thatis effective for all situations. Both land-based and sea-based systems are required. Thus both the Army andthe Navy became involved in TMD. Both services be-gan development of systems that would operate atlow altitudes (endoatmospheric) as well as at high al-titudes (exoatmospheric). The systems, shown inTable 1, are designed to protect expeditionary forcesagainst attacks by ballistic missiles. The Laboratory’swork in TMD was and continues to be critical to thesuccess of the program. Key areas of the Laboratory’sinvolvement are listed below.

Discrimination. The wide variety of theater missilessystems, their behavior, their signatures, and theircountermeasure capabilities require new and robust

discrimination algorithms. The Laboratory continuesto be foremost in this area. Two particular areas ofconcern are the filtering of clutter as boosters disinte-grate during reentry, and the correlation of tracks be-tween surface-based radars and interceptor IR seekersduring the final stages of an intercept.

Theater Critical Measurements Program. To investi-gate signatures of putative countermeasures, theLaboratory has been and is conducting a series ofwell-instrumented field tests at Kwajalein. Threecampaigns consisting of two or three flights each havebeen conducted thus far. The devices flown on thesetests were designed and built by the Laboratory. Theanalysis of the test data has led to new discriminants.

THAAD Radar. The radar for the Theater High-Altitude Area Defense (THAAD) system is a new andpowerful phased array that incorporates several noveldesign features. (The radar was designed, developed,and built by Raytheon.) Early in its design phase,Laboratory staff aided in defining the radar require-ments and in critiquing the radar design. Later theLaboratory staff analyzed data from prototypes of theTHAAD radar and evaluated its performance.

Navy Theater Wide. Several studies were conductedto determine the effectiveness of Navy assets in a the-ater-wide role. The studies determined where im-provements or new capabilities (especially for radars)were needed. The Laboratory played a major role inthese studies by making major design recommenda-tion for the Navy radar systems after conducting a

Table 1. Theater Missile Defense Systems

Low Altitude High Altitude

Army Patriot Advanced THAADCapability (PAC-3)

Theater HighAltitude AreaDefense (THAAD)

Navy Navy Area Defense Navy Theater Wide(NAD)* (NTW)

*In December 2001, the NAD System was discontinued bythe Department of Defense.



design and performance analysis of more powerful ra-dars. The Laboratory also was a key contributor ofdiscrimination technology for use in these systems.

THAAD System Tests. Some of the first THAADsystem tests failed; others were only partially success-ful. In cooperation with staff from other organiza-tions, Laboratory staff analyzed the data to determinethe cause of the failures.

TMD Netting. With the large number and varietyof TMD systems likely to be deployed in a theater ofoperations, it is important that these systems be net-ted through a battle-management, command, controland communication network. Netting provides aneconomical use of interceptors, reduces missile leak-age, and aids the discrimination process. The Labora-tory has been very active in this area. In 1994 theTheater Defense Netting Study (TDNS) was carriedout under the leadership of Laboratory staff. Thestudy showed that significant performance gains canaccrue if TMD systems are netted during a missile at-tack. Since the study, the Laboratory has continued toexamine netting especially as it aids discrimination.

National Missile Defense

The NMD Program was recast as a technology-readi-ness program in 1993 and its funding was drasticallyreduced in order to emphasize the TMD Program.Coping quickly with an emerging threat required asystem architecture based primarily on surface-basedcomponents (radars and interceptors). In the late1990s, IR sensors on satellites were integrated intothe architecture. The threat facing NMD consists of afew missiles but with very sophisticated countermea-sures, and is assumed to originate from any of severalgeographically dispersed nations. An NMD system isneeded to ensure that leakage will not exceed an ex-tremely low amount. These assumptions and require-ments make the discrimination requirements verystringent.

In more recent times the NMD Program has be-come a deployment-readiness program. In 1997 a“3 + 3” schedule was adopted. Under that schedule,development and testing would occur over the nextthree years with a deployment readiness review in2000. Although the initial deployment, if warranted,was to have been in 2003, the schedule was modified

in 1999 so that the initial deployment would occur in2005 (with a presumed reduction in technical risk)[13]. The change in the NMD Program to deploy-ment readiness resulted from a proliferation of long-range ballistic missiles by so-called third-world coun-tries, some of whom have interests inimical to theUnited States and its friends and allies. As of the dateof this article, the architecture for NMD is undergo-ing review, and its exact composition is unknown.The components listed in Table 2, however, are ex-pected to play a role in NMD.

Discrimination

The Laboratory’s role in this program continues to befocused on discrimination algorithms and on dis-crimination schemas. The extremely low leakage re-quirements and the multitude of possible counter-

Table 2. National Missile DefenseSystem Components

Surface-Based Radars

Upgraded Early Warning Radars (UEWR)

Position and Velocity Extraction Phased ArrayWarning System (PAVE PAWS)

Ballistic Missile Early Warning System (BMEWS)

X-Band Ground-Based Radar (XBR)

Radars on Navy ships (Aegis)

Space-Based Sensors

Defense Support Program (DSP)(initial version of NMD only)

Space-Based Infrared Sensor (SBIRS)–High

Space-Based Infrared Sensor (SBIRS)–Low

Weapons

Ground-Based Interceptor (GBI)

Navy Ship-Based Interceptor

Airborne Laser (ABL)

Space-Based Laser (SBL)



measures that have been postulated by countermea-sure specialists make this one of the key technical ar-eas that must be resolved for a successful NMD sys-tem. As in the case for TMD, the fusion of data fromseveral sensors should aid the discrimination processand is being actively pursued.

Range Support, Measurements, and Data Analysis

The primary location for the collection of data rel-evant to NMD continues to be the Kwajalein MissileRange (KMR). The Laboratory’s radars at KMR arethe nation’s premier asset for this collection, and theyare used whenever any U.S. test planned to impactnear the Kwajalein Atoll is conducted. Test planning,radar operations, data reduction, and data analysis areall conducted by Laboratory staff and contribute todiscrimination research as well as to NMD perfor-mance evaluation.

Foreign-Data Collection

The proliferation of the threat to several countries(together with the proliferation of missile systems)make it mandatory that data on foreign missiles becollected and analyzed whenever possible. The Labo-ratory participates in this endeavor and is a majorcontributor to the understanding of the capabilitiesof foreign missile systems.

Architecture Studies

With the large number of sensors and weapons beingconsidered for NMD architectures, shown in Table 1,it is essential that trade-offs be made of the overall sys-tem performance as the mix and use of system ele-ments changes. The Laboratory is one of several orga-nizations engaged in these studies.

Summary

Throughout approximately a forty-five-year period,the U.S. objectives in ballistic missile defense haveundergone changes. The changes have been made inresponse to three factors: the perceived threat, thetechnology available to meet the threat, and above allthe calculus that provides the greatest security for theUnited States. However, during this same periodmany of the key technical issues of BMD have re-mained the same. These are discrimination, architec-

ture design and evaluation, and technology leading tonew system elements. Lincoln Laboratory has playeda key role in all these issues and has made importantcontributions to BMD. Figure 5 shows a timeline ofevents and achievements in Lincoln Laboratory’s pro-gram in BMD. Figure 5 also shows the major eventsthat influenced the focus of the U.S. BMD program.

Acknowledgments

Each article in this special issue of the Lincoln Labora-tory Journal was reviewed by at least one BMD spe-cialist outside the Laboratory and one BMD specialistat the Laboratory. Their careful scrutiny of the textand helpful suggestions greatly improved the qualityof each article, and we thank them for their efforts.The reviewers are listed in Table 3 with their currentaffiliations.

In addition to reviewers, this issues owes suchqualities as it might possess, and even its very exist-ence, to numerous people at Lincoln Laboratory whocontributed essential services. We thank them fortheir invaluable support.

Table 3. BMD Reviewers

Reviewer Affiliation

Mark Bernstein Lincoln Laboratory

William P. Delaney Lincoln Laboratory

George Dezenburg SAIC

John C. Fielding Raytheon

J. Richard Fisher DESE Research, Inc.

Richard Gray Nichols Research (retired)

Michael S. Holtcamp Holtcamp Associates, Inc.

Leslie A. Hromas TRW

Robert H. Kingston Lincoln Laboratory(retired)

Michael Lash SMDC Technical Center

Charles. W. Niessen Lincoln Laboratory

Glen Pippert Lincoln Laboratory(retired)

William P. Schoendorf Torch Concepts, Inc.



R E F E R E N C E S1. E.C. Freeman, ed., MIT Lincoln Laboratory: Technology in the

National Interest (Lincoln Laboratory, Lexington, Mass.,1995).

2. H.E. Guerlac, Radar in World War II, vol. 8, bk. 1 (A–C) andbk. 2 (D–E), The History of Modern Physics, 1800–1950(Tomash Publishers, Los Angeles, 1987).

3. In 1909, the U.S. Army specified that its “Airplane No. 1” mustachieve a speed of 65 kph. By 1918, the heavily armed (British)Bristol F.2b had a top speed of 200 kph.

4. In place of the Rad Lab, the Research Laboratory for Electron-ics (RLE) was formed, a smaller counterpart with academicrather than military overtones.

5. J.F. Jacobs, The SAGE Air Defense System: A Personal History(MITRE Corp., Bedford, Mass., 1986).

6. Whirlwind I had been developed at the MITServomechanisms Laboratory for the Office of Naval Re-search, to be part of a flight simulator. The Navy released it tothe Air Force.

7. It became clear that the new laboratory would eventually bebased, not in Cambridge, but rather on Hanscom Air ForceBase, which lies at the juncture of the towns of Bedford, Con-cord, and Lincoln. Projects involving the names “Bedford” and“Concord” already existed, so the new laboratory took its namefrom the third town. “Project Lincoln” became “Lincoln Labo-ratory” soon thereafter.

8. D. Lennox, “Threats—Development and Proliferation of Bal-listic and Cruise Missiles,” Seventh Multinational Conf. on The-ater Missile Defense: Theater Missile Defense: Systems and Is-sues—1994, Annapolis, Md., June 1994, pp. 29–36.

9. P.A. Ingwersen and W.Z. Lemnios, “Radars for Ballistic MissileDefense Research,” Linc. Lab. J., vol. 12, no. 2 (2000), pp.245–266.

10. W.W. Camp, J.T. Mayhan, and R.M. O’Donnell, “WidebandRadar for Ballistic Missile Defense and Range-Doppler Imag-ing of Satellites,” Linc. Lab. J., vol. 12, no. 2 (2000), pp. 267–280.

11. A.J. Fenn, D.H. Temme, W.P. Delaney, and W.E. Courtney,“The Development of Phased-Array Technology,” Linc. Lab.J., vol. 12, no. 2 (2000), pp. 321–340.

12. R.J. Purdy, P.E. Blankenship, C.E. Muehe, C.M. Rader, E.Stern, and R.C. Williamson, “Radar Signal Processing,” Linc.Lab. J., vol. 12, no. 2 (2000), pp. 297–320.

13. “Harnessing the Power of Technology: The Road to BallisticMissile Defense from 1983–2007,” Ballistic Missile Defense,Sept. 2000.

14. This missile defense system called Global Protection AgainstLimited Strikes (GPALS) included not only defense of theUnited States, but also defense of U.S. Allies. This latter re-quirement was subsequently dropped and the basic architec-ture of GPALS, many of its system elements, and even thename did not survive for long.



. received an S.B. degree inelectrical engineering fromMIT and an M.S. degree inphysics from the University ofIllinois. His early work at theLaboratory included designand programming of theintercept function of the CapeCod System and the SAGEsystem (both prototype sys-tems of continental air de-fense), and analyses of theacquisition and tracking capa-bilities of the Ballistic MissileEarly Warning System radars.From 1963 to 1969 he wasassociate leader and thenleader of the Systems Analysisgroup, where he was engagedin the design, fabrication, andperformance evaluation ofballistic missile penetrationaids. From 1969 to 1993 heserved as assistant head, associ-ate head, and head of theRadar Measurements division.He is now a consultant to thedivision as well as a member ofthe Independent Science andEngineering group that advisesthe Ballistic Missile DefenseOrganization on mattersrelated to ballistic missiledefense. Among his awards arethe Outstanding CivilianService Medal, conferred bythe Secretary of the Army. Heis a lifetime Senior Member ofthe IEEE, a Senior Member ofthe American Institute ofAeronautics and Astronautics,and a member of the Ameri-can Physical Society, theAmerican Association for theAdvancement of Science, andthe Society of Sigma X.

. received a B.A. degree inphysics from Columbia Col-lege, an M.A. degree in math-ematics from Columbia Uni-versity, and an M.B.A. degreefrom Western New EnglandCollege. He joined LincolnLaboratory in 1956, workingfirst on the SAGE air defensesystem, then on ballistic mis-sile testing, analysis, andevaluation. In 1989, after 33years at Lincoln Laboratory asstaff member, group leader,and senior staff, he retired—atransition that his wife claimsto have seen little evidenceof— and has since workedpart-time at the Laboratory. In1999 he published The Rootsof Things—Essays on QuantumMechanics, and he is currentlywriting a book on specialrelativity.

overview of the lincoln laboratory ballistic missile defense program

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