Project PRESS (Pacific Range Electromagnetic Systems Studies) was the major field measurement element of ARPA's research on phenomenology of the reentry into the earth's atmosphere of inter-continental ballistic missiles (ICBMs) under its DEFENDER program. The largest part of DEFENDER, which was transferred to the Army in 1967, PRESS and the Army's follow-on Kiernan Reentry Measurements Systems (KREMS) facilities and measurements have played a key role in assuring credibility of the U.S. ICBM offensive deterrent and in U.S. decisions about Ballistic Missile Defense (BMD) R&D and system deployment The TRADEX, ALTA1R, and ALCOR radar systems resulting from PRESS are in use today by KREMS at the Army's Kwajalein Test Site where they support R&D for Air Force penetration systems and Army and Strategic Defense Initiative (SDI) BMD efforts. These systems are also in operational use by the Air Force in SPADATS and for Space Objects Identification (SOI) work. Airborne optical and IR measurements, originated under PRESS and continued under DARPA Strategic Technology Office (STO) sponsorship, have contributed to the design of sensors for midcourse terminal homing intercept systems under SDI.


I. Background

In the late 1950s a number of U.S. government actions resulted from a sharply growing appreciation of the Soviet ICBM potential, fueled by the Soviet's test of a ballistic missile of intercontinental range and their successful launching of SPUTNIK. There was an acceleration of efforts on die defensive side with the NIKE-ZEUS BMD system then being carried on by Bell Telephone Laboratories (BTL) under Army sponsorship (then a top DoD priority) and also with the Air Force's long range WIZARD radar, space based ABM (Anti Ballistic Missile) projects, and MIDAS early warning satellite effort On the offensive side-die prime basis of U.S. deterrent to date-Air Force efforts toward an operational ICBM system were speeded up. There were several high-level studies of the technical aspects of the ICBM problem which emphasized particularly the need for better understanding of ICBM reentry phenomena in order to enah'e the defense to discriminate between decoy debris and reentry vehicles containing warheads. These studies also addressed countermeasures which could assure penetration of U.S. offensive missiles through Soviet BMD systems that were then believed to be under development1

A key related action of the Eisenhower administration was the establishment of ARPA. To get the United States going in space in a reasonable way without Service-related bias (the Army and the Air Force were in strong competition for missions in space) was, chronologically, ARPA's first assignment The second major assignment, with the same flavor of helping the president deal with inter-Service rivalry,2 was DEFENDER, oriented toward advanced approaches to BMD. While this DEFENDER assignment was second chronologically, the earliest ARPA Congressional hearings indicate it was first in priority.3 The DEFENDER assignment was to:4

....undertake research, experimentation, development and long term feasibility demonstrations to obtain technologically advanced defense against extra-atmospheric offensive vehicles, including space vehicles and ballistic missiles. It is intended that this project be pointed toward the exploitation of fundamental phenomena; the development of new systems concepts; and the applications of new techniques as opposed to development and refinement of authorized defense systems which will be the responsibility of the military departments.

NIKE ZEUS was, at the time, such a major authorized defensive system with development started by the Army, but responsibility for it was given also to ARPA. However, NIKE ZEUS was quickly evaluated by Roy Johnson, the first ARPA director, as too close to a procurement decision to fit ARPA's assignment One of the first ARPA actions was to return the responsibility for NIKE ZEUS to the Army,5 and to concentrate its efforts on the more fundamental unknowns and advanced approaches mentioned in its assignment

Another related ARPA assignment, mentioned in the same DoD directive, was to investigate advanced technologies for "penetration aids" for ICBM warheads. The Air Force had already begun some effort in this direction.6 It was recognized early-on mat the same type of measurements of reentry phenomenology were essential to the penetration aids programs as for BMD programs.

An outline of specific directions for project DEFENDER was provided by previous studies, notably by the Bradley PSAC and RBIG (Reentry Body Identification Group) panels. The ARPA DEFENDER effort, guided in part by these studies, encompassed a very wide range of technologies underlying early warning, long range and terminal BMD approaches and penetration aids, including phased array and over-the horizon radars, high power electronic tubes, long range BMD and ASAT systems, nuclear effects and non-nuclear hypervelocity impact systems for destruction of reentry vehicles (RVs), lasers, and charged particle beams as directed-energy weapons, infrared emissions from rocket plumes and reentry, and a new ionospheric probe (ARECIBO) with a 1,000-foot antenna. The Bradley studies had emphasized the complexity of the BMD problem, and pointed out mat there were many unknowns in the reentry phenomenology, which might or might not be critical for BMD system design. Among these were not only the phenomena associated with the hypersonic reentry of RVs into the normal atmosphere, but also the effects of nuclear explosions which were expected to be frequent in the reentry scenarios then discussed.7 In response, many of the earliest ARPA orders under project DEFENDER were concerned with the nuclear effects areas,8 and included extensive programs in relevant atomic and molecular physics, and in the physics, chemistry and hypersonic aerodynamics of reentry. These ARPA activities built on the previous and ongoing related DoD and Atomic Energy Commission (AEC) work.9 Held measurements were understood to be of major importance and were undertaken by ARPA with a wide range of active and passive sensors, using and expanding available Service and NASA facilities at Wallops Island, the Army White Sands Missile Range (WSMR), and the Atlantic Missile Range (AMR). Some significant extensions of these field capabilities were also made by ARPA, notably in the outfitting of the DAMP (Down Range Anti-Ballistic Measurement Program) ship.10 (See Figure 1-1.)

ARPA became the strongest player in the field measurement game, not only to carry out its responsibility under the DEFENDER directive, but also because the White House wanted an "honest broker" between the Air Force, with its rapidly developing, primarily offensive ICBM orientation, and the Army with its defensive ABM effort Besides, there was an urgent demand for more reentry data, especially field data, by all involved, and ARPA could move quickly to obtain it.11

There was an early appreciation by ARPA's leadership of the difficulties of integrating a very complex measurements effort when it would all get underway, especially the experimental field work which would include measurements on the Atlantic test range, on land, and some on the DAMP ship.12 Accordingly, one of the earliest actions of ARPA's top staff was to approach MFTs Lincoln Laboratory as to whether they could undertake a major responsibility to pull together the national effort13 However, Lincoln did not choose to take on such a major responsibility at this time. It did "leave the door open" and agreed to increase their field measurements effort, together with an expansion of laboratory and theoretical efforts on hypersonic phenomena, and an increased effort on data processing specifically requested by ARPA in anticipation that this would eventually become a major problem area for BMD. Lincoln also lent one of their key reentry scientists to ARPA/IDA, which is discussed at length below. Lincoln had already been involved with NASA and the Air Force in setting up a suite of sensors (both radar and optical) at the NASA Wallops Island test facility, where tests of rockets and reentry vehicles were going on, and making distant observations of these objects with its MILLSTONE HILL radar.14 This early Lincoln effort had a remarkably "unfettered" charter for its research.


Figure 1-1. DAMP Ship, USAS American Mariner

ARPA's field measurements program continued for more than a year after Lincoln's turn-down, under direction of the DEFENDER IDA/ARPA group. In particular, ARPA proceeded to quickly develop and exploit the DAMP ship which had the important features of positional mobility with respect to the trajectories of reentry vehicles, and because optical, microwave radiometric, and IR measurements could be all made from the same stabilized platform on the ship.13 A similar effort was made to use aircraft for optical and infrared observations, some of which had been outfitted previously. Some of these aircraft were "drafted" to make the first U.S. observations of reentry events provided by Soviet ICBM tests in 1960. The first ARPA measurements of U.S. ICBM reentry events were made by DAMP on the AMR in 1961. DAMP made valuable measurements also during the FISHBOWL nuclear test series in 1962, but was terminated in 1963.

In the late 1950s ARPA also made arrangements with the United Kingdom to make measurements associated with tests of their BLACK KNIGHT ICBM at the Australian Woomera Test Range.16 Particular interest attached to the advanced "low observable" RV designed for this missile by the U.K.'s Royal Radar Establishment.

A particularly important feature of this early DEFENDER work was that ARPA soon came to regard it as a program of scientific measurement and analysis. To this end ARPA set up several mechanisms for data archiving and organized scientific exchange on topics of importance. One of these was a series of regular AMRAC (Anti-Missile Research Advisory Committee) Symposia held biennially until 1969 through an ARPA contract with the University of Michigan, at which scientific discussions of the results of all relevant work could take place. The BAMIRAC project, also at the University of Michigan, provided for archiving missile phenomenology data and modeling, initially encompassing all aspects from launch to reentry; later, BAMIRAC specialized more in IR phenomenology. The scientific archives of AMRAC and BAMIRAC have been invaluable also for the BMD efforts carried on after DEFENDER by the Services and SDI.17 Later, in 1963, Dr. C. Herzfeld, then DEFENDER project director, started the Journal of Missile Defense Research (JMDR) which became in 1968 the present Journal of Defense Research as a medium for classified scientific communication in the area, with a degree of quality control by "peer review."

In roughly the same time frame, the Bell Telephone Laboratories (BTL) had constructed NIKE ZEUS radars at WS MR and also a NIKE-ZEUS target-track radar facility at Ascension Island, near the region of reentry of ICBMs being tested at the AMR, and beginning in 1961 had subcontractors (AVCO and Cornell Aero labs) making related optical and infrared observations in aircraft.18 These field efforts were supplemented by laboratory and theoretical work. Together with the DAMP and other available data, these early BTL observations were used in attempts to find some single discriminants or combination of such, to identify and track reentry vehicles (RVs) among missile tankage, debris, and decoys. The first discriminants investigated included aerodynamic deceleration in the atmosphere, and the associated doppler and scintillation characteristics of radar returns at different frequencies, polarizations and pulse formats, and emissions in the optical, infrared, and microwave spectral regions. Extensive discussions of such BMD discriminants are chronicled in the early AMRAC processing and issues of JMDR.19

The HARDTACK series of nuclear explosions in the fall of 1958 included the TEAK and ORANGE high altitude events, which were aimed in part at measuring the attenuation of electromagnetic waves in the large affected atmospheric volumes, important for selection of radar frequencies of BMD systems which were expected to operate in such environments.20 Such measurements were made during TEAK and ORANGE under ARPA auspices and also by the BTL NIKE ZEUS group. The results, together with those from later experiments in the FISHBOWL series in 1962, and an appreciation of the difficulty and cost of constructing radars at different frequencies, developed partly by the ongoing ARPA efforts on high power sources, had a major eventual impact on the design of the reentry measurement radars in DAMP and elsewhere, and on the NIKE X and later BMD systems 21

Lincoln Laboratory, with a strong background from their earlier BMEWS and MILLSTONE HILL radar design experience, had participated in the design of the radars on the DAMP ship which were built by RCA. In 1958, shortly after ARPA's beginning, Lincoln "lent" Dr. G. Pippert to the IDA/ARPA division.22 One of Dr. Pippert's first activities was to discuss with RCA (which had built several precision range tracking radars, including those used on the DAMP ship and the BMEWS radars) a concept for a large ground-based radar for accurate ICBM tracking and measurements, featuring coherent operation and ability to generate a variety of pulse trains. The need for such a ground-based precision tracking radar, to make accurate measurements of trajectories and in order to guide other sensors, had been underlined by experience on the AMR.23 The flexibility provided by the different pulse trains together with the coherence, was also expected to allow measurements of the ionized hypersonic RV wake structure, as well as of the RV bodies' scattering characteristics. RCA quickly developed a proposal for this radar, eventually called TRADEX (tracking and detection experiment radar) which was accepted by ARPA.24 TRADEX was mechanically steered, but its signal formats gave it high range resolution for accurate tracking as well as measurement It was first planned to operate at UHF. Work soon began on the radar, apparently before the final decision had been made as to where it would be located.

In 1958-9, partly because of advantages for polar orbits for satellite launches, the Air Force constructed its main ICBM launch complex at Cooke AFB, later named Vandenberg AFB.23 In the same time period the Army selected Kwajalein atoll in the Pacific as a test site for its NIKE ZEUS system. To provide RVs for test of NIKE ZEUS, the Army proposed to launch its JUPITER Intermediate Range Ballistic Missiles (IRBMs) from Johnson Island, with rockets to augment downward reentry velocity (as had been done at Wallops) to simulate ICBM reentry. It was expected by DoD planners that the Air Force would soon launch ICBMs into the Pacific Missile Range from Vandenberg, which could provide realistic RVs for test of NIKE ZEUS. Because of "inter-Service rivalry," magnified by the arguments between the Strategic Offense (AF) and Defense (Army), there may have been some Air Force reluctance to allow its RVs to be used for NIKE ZEUS tests, and on the other hand the Army preferred an "organic" operation under its control26 In any case, the DoD plans, which were in line with Pres. Eisenhower's desire to keep the Army out of the missile launch picture, prevailed. Dr. H. York, the first DDR&E, ruled in early 1960, when he found out about the situation, that only real ICBM RVs would be shot into the Kwajalein area.27

2. Project PRESS

ARPA recognized the difficulties of doing accurate measurements on the AMR, and the opportunity and great economy involved in using the same reentry events as would NIKE ZEUS in a location for which logistics and other arrangements were being made by the Army, as well as the advantage of being able to interact closely with the NIKE ZEUS observations being made by the system being built by BTL at Kwajalein. Consequently, in Fall 1959, ARPA set up project PRESS with its major facilities to be located in the reentry area, on Roi Namur, another island in the Kwajalein atoll chain.28 The original plans for the PRESS facilities included the PINCUSHION experimental radar, another ARPA-funded project, and TRADEX.29

Through the persistent efforts of Dr. J. Ruina, then Assistant DDR&E, Lincoln Laboratory accepted a coordinating role for the entire national reentry measurements efforts, as well as technical supervision and coordination of all military efforts on penetration aids, target identification and reentry physics, as well as technical direction of project PRESS.30 Preliminary to this, Lincoln had apparently reviewed an ARPA study of the PRESS role in the overall reentry measurements problem, and in response recommended that a single organization be in charge. It was envisioned in this study that PRESS would involve TRADEX and possibly other radars later, together with various ground and air based optical and IR sensors. The PRESS radar facilities were planned to be all under computer control, and to have extraordinary data reading capabilities.31 This preliminary Lincoln review also recommended against going further with PINCUSHION because of anticipated technical difficulties with its new design and with the high-power S-band transmitters required.32

Construction of TRADEX and associated PRESS facilities began at Roi-Namur in early 1961.33 TRADEX incorporated a new high-power L-band transmitter tube developed 4 under ARPA sponsorship. In April 1962, TRADEX began operations by RCA, and shortly afterwards Lincoln personnel arrived to take over. In June of that year, TRADEX successfully tracked the first Air Force ICBM reentry event at Kwajalein, along with the NIKE ZEUS radars. In July 1962 the first successful NIKE ZEUS intercept of an ICBM occurred at Kwajalein. TRADEX (see Figure. 1-2) was the first and only dedicated measurements radar at Kwajalein till 1968, and after many successive upgrades, remains in use to date.34

Between 1960 and 1962, apparently, the level of activity at Lincoln associated with PRESS was not high.33. Shortly after Lincoln staff arrived at Roi-Namur, ICBMs began to arrive and much data began to be gathered on reentry phenomena. The PRESS capabilities at Roi Namur were soon augmented to include an optical telescope and a Baker-Nunn open slit spectrograph, similar to those that had been used at Wallops Island, and the WSMR, and also other optical and infrared systems. Optical and IR instruments on existing aircraft were also improved, and another aircraft was specially outfitted for PRESS.36 Data analysis done initially at Roi Namur was found to be difficult to manage there because of the time required and complexity of preparing for the frequent reentry events. As a result, data packages were soon air mailed back to Lincoln for analysis.

The optical and IR sensors in the PRESS aircraft after some initial difficulty eventually were directed successfully using TRADEX. The optical results were particularly valuable for investigation of emissions associated with chemical phenomena in wakes, which were especially complex from ablating RVs.

The scientific data from PRESS, along with some from the parallel BTL Range Measurements Program (RMP), were reviewed in monthly meetings starting in early 1959 and a little later presented, along with relevant analyses, in the ARPA-sponsored AMRAC symposia. Many different types of RV targets were observed. A synergism developed rapidly using results of the laboratory and theoretical efforts on reentry phenomena together with the field results.37 Some of the NIKE ZEUS radars, which initially had modest coherent capability, eventually increased coherence bandwidth partly as a result of TRADEX's performance.31

Beginning in 1962 when concern rose about the potential of Soviet BMD systems, the Air Force began a major effort on penetration aids, initially with ARPA funding, and the Navy's plans for POLARIS included multiple reentry vehicles (MRVs).39 Later (in 1963) the Air Force was given the assignment of coordinating U.S. penetration aids efforts under project ABRES.40 ARPA funding of a program dedicated to R&D on "Penaids" continued through 1966, and thereafter on a more opportunistic basis. In 1965 ARPA also funded the "Pen X" study, which reviewed the problem of Penaids versus multiple independent reentry vehicles (MRVs). Pen X provided some input to the DoD decisions to deploy MIRVs. However, this decision seems to have been primarily due to simple economic considerations related to missile costs.41

As mentioned above there was an early appreciation of the need to thoroughly understand both offensive and defensive systems' capabilities in order to make decisions on the balance required for cost-effective national security. The key question for the defense was whether some practically useful discrimination phenomenon or combination of phenomena existed to lessen the defense's burden of identifying RVs in time to be able to launch and guide a missile to destroy it. The offensive (penetration) side of the same problem was the search for ways to minimize or mask the RVs observables for some critical length of time, and the key question was how many, how heavy and large penetration aids, which displaced destructive warhead payload, would be cost effective. While the Army and Air Force had opposite sides of this problem, ARPA was set up to be able to work both sides, and indeed PRESS was set up to make accurate qualitative measurements of the same phenomena which affected both sides. Not long after PRESS was underway, DDR&E sponsored regular meetings involving offensive and defensive sides with Lincoln and ARPA as active participants and "honest brokers." Key to being able to do this, of course, was DDR&E H. York's 1960 decision to force both Services to use the same reentry site at Kwajalein, and in ARPA's setting up the PRESS operation there to provide high quality scientific information to both sides (defensive and offensive), as well as enabling independent analyses be done by and through ARPA.

Before the end of 1962, President Kennedy made the decision, after many studies and debates, not to deploy NIKE ZEUS because of the apparent vulnerability of NIKE ZEUS to simple countermeasures.42 It is not clear what part, if any, PRESS had in this decision. Not many reentry measurements had yet been made by PRESS and apparently few penetration aids of any sophistication had been tested.43 The BTL history of BMD states that the decision was due to a change in the threat from one-on-one engagements (a single NIKE ZEUS installation could only handle one RV/missile at a time) to a high traffic threat, involving simultaneously many RVs and many interceptors. Multiplication of individual NIKE ZEUS type systems to meet this new threat was not considered cost effective.44 Other considerations involved were: the fact that the ZEUS missile speed required launch before "atmospheric filtering" of RVs from lighter decoys, debris, craft, etc., could take place; the reality of the Soviet penetration aids threat for U.S. BMD, which remained a matter of contention throughout the BMD project;45 and the vulnerability to nuclear blasts of the mechanically steered NIKE ZEUS radars. After the President's decision, NIKE ZEUS continued through 1962, making successful intercepts of several types of ICBMs, and the BTL target tracking and discrimination radars continued to make reentry measurements for several years.

While cancelling NIKE ZEUS, the administration also gave its backing to continued ABM R&D, specifically along the lines of a concept called NIKE X, involving a hardened phased array radar and a high acceleration missile to make close-in intercept after atmospheric screening-out of light decoys and other debris. The name NIKE X was apparently due to Dr. J. Ruina, then ARPA director, who had the task of laying out the options for DoD and the President's Science Advisory Committee (PSAC).46 BTL describes NIKE X as a transition R&D phase toward the next generation BMD system. Apparently from about 1960 a high acceleration missile had been under study at BTL and a phased array also, after the stimulation of ARPA's successful ESAR project and an explicit request by DoD.47

In early 1963, apparently prompted in part by intelligence about Soviet ABM developments, as well as about their prospective offensive capabilities, the Secretary of Defense ordered the priority development of NIKE X. The NIKE program by then had begun construction at WSMR of a hardened phased array radar, the MAR,48 and of a short range high velocity missile (SPRINT); in 1964 the program incorporated a thermonuclear warhead, on a longer range version of the ZEUS missile (SPARTAN)49 for exoatmospheric X-ray kill of RVs, providing a kind of area defense.

The fact that SPRINT and SPARTAN had nuclear warheads emphasized the importance of understanding the characteristics of ABM systems operation under conditions in which nuclear explosions occurred in and above the atmosphere. Many then felt that the theoretical assessment of such situations should have been compared with dedicated experiments involving real nuclear explosions. However, with the atmospheric nuclear test ban, no further experiments occurred.30 ARPA funded several related experiments connected with the FISHBOWL nuclear test series in 1962, and some of the data analysis.51

As part of NIKE X, in 1964 BTL intensified its own reentry measurements and analysis program.52 Overall reentry test requirements, in the mid 1960s, began to be coordinated in a tri-Service coordinating group and an ARPA-Army agreement was established specifically to coordinate the RV measurements program.53 The respective responsibilities, described from the viewpoint of BTL, were as follows:54

1. Bell Laboratories. Specified program objectives, reentry hardware performance requirements, and target delivery (trajectory and deployment) requirements. Operated the NIKE radar sensors and EC121 optical aircraft Reduced and analyzed collected data.
2. Army. Procured target vehicles and delivery systems through the Air Force. Coordinated test requirements, program objectives, and schedules. Provided the Kwajalein Test Range support Coordinated inter-Service data exchanges.
3. Air Force. Provided the reentry hardware, booster systems, and the ETR (Reentry Test Range) facilities (i.e., delivered targets to Kwajalein Test Site). Exchanged technical data and coordinated their reentry study program, ABRES, to support missions of mutual interest
4. Lincoln Laboratory. Supplied technical consultation and coordinated design of reentry experiments and data analysis exchange. Operated additional sensors (data sources) of the PRESS facilities at KTS.

In the early 1960s intelligence about a Soviet ABM radar, and an appreciation that penetration aids were as yet used in very few of the U.S. ICBMs, suggested a specific need to better understand reentry phenomenology as observed by radars operating in the VHF frequency range.55 This led to Lincoln design, about 1964 of a new, higher power radar with dual frequency capability, at VHF and UHF, called ALTAR (ARPA Long Range Tracking and Instrumentation Radar) as the next major PRESS sensor at Roi-Namur (see Figure 1-2). The primary motif for ALTAIR apparently was to simulate the Soviet BMD radars' capabilities against U.S. RVs.56 It was also considered important to obtain accurate experimental data on reentry phenomena at different frequencies, even if some of them were low enough to be significantly affected by nuclear explosions. Before ALTAIR was built, however, TRADEX was modified to provide some interim VHF observational data. Like TRADEX, the construction of ALTAIR was funded separately.57 ALTAIR became operational about 1969.

Shortly after commencing work on ALTAIR, Lincoln proposed that a large bandwidth, high resolution C-band radar [ALCOR (ARPA - Lincoln C-band observable radar)] be constructed. (See Figure 1-2.) TRADEX and other data had indicated that high resolution images of RVs and of the structure of their wakes might be very important To obtain very high resolution, a wider bandwidth (500 MHz) and a higher radar frequency were required than provided by TRADEX and ALTAIR.58 Like TRADEX, ALTAIR and ALCOR (and the later millimeter wave radar), as experimentally oriented systems, were mechanically steered, not having the multiple-target BMD problems which required a phased array. ALCOR became operational about 1970 at Roi-Namur.

Figure 1-3 outlines the history of upgrades of radars originating in PRESS, up to 1980. In the mid 1960s a wide bandwidth, similar to ALCOR's, was included in the ARPA Synthetic Spectrum Radar, built by Westinghouse and used in SOI studies and in the design studies of ADAR (Advanced Array Radar), for hardened site defense systems with capabilities beyond that then planned for NIKE X.59

Throughout this period (early to mid-1960s) there were a large number of ICBM and SLBM tests involving different types of RVs and penetration aids. Some of these were of special design for the ABM projects, and some RVs carried instruments to make special measurements on board to determine the properties of plasma sheaths and wakes. A number of experiments, with ATHENA intermediate-range missiles and special RVs were also conducted in the mid-1960s at WSMR.60 The WSMR radars used for these experiments included BTL's NIKE ZEUS and MAR radar, and ARPA's AMRAD measurements radar, operated at first by the Columbia University electronics laboratory group, (later the Riverside Research Institute) and eventually turned over to Lincoln. The WSMR measurements, lacking real ICBMs, but under somewhat better control, and often allowing a closer comparison with laboratory reentry physics experiments, were a valuable complement to those at Kwajalein and Roi Namur. These WSMR activities continued to the mid-1970s.

In the late 1960s several summary studies were conducted to assess the state of understanding of reentry phenomenology and its applicability to NIKE X.61 While these and other similar studies underlined the continuing difficulty of discrimination problems, at the same time they apparently indicated a sufficient level of capability of a NIKE-X type system against a presumed unsophisticated penetration-aids threat from China to help persuade DoD in 1967 to propose deployment of a "thin" BMD system, called SENTINEL.

In 1967, at about the same time as the SENTINEL decision, the major pan of project DEFENDER was transferred from ARPA to the Army, along with some key personnel and the PRESS facilities.62 Dr. J. Foster, then DDR&E, directed the transfer, noting that DEFENDER'S objectives had been largely reached, and that the Kwajalein facilities, including PRESS, should be regarded as national assets. In response the then Army Chief of R&D, Gen. A. Betts, who had been an earlier ARPA director, reorganized his command to identify clearly its ABM-related R&D effort in an Advanced Technology Program of which the ex-ARPA personnel were now in charge. As specified by the DDR&E, the Army continued Lincoln's management of PRESS in support of ABM R&D and the Air Force's ABRES project The PRESS facility was renamed the Kiernan Reentry Measurements Facility (KREMS) after LtCol Joseph Kiernan, who had managed the ARPA PRESS program from 1963 to 1966 and was killed in Vietnam.63

Figure 1-3. Chronology of Radar Changes (from Hottcamp, op. cit.)

In summer 1968 an ad hoc committee, including representatives from ARPA, cognizant Army agencies, DDR&E, and the major contractors BTL and Lincoln, developed a coordinated plan for continued use of some of the Kwajalein radars and retirement of others, which was then approved by the DDR&E reentry programs review group overseeing the transfer and subsequent actions. In fall 1968 the same committee devised plans for integration of these sensors, providing a measure of independence along with improved communications by which the radars would provide data to each other and to an upgraded central data processing system. Previous to this, apparently, BTL had set up a high-capacity data link between PRESS and their NIKE X radars.64 In the 1967-72 period, there was very close collaboration of the Lincoln and BTL groups not only on reentry measurements, but also on system-related activity, such as determining miss distance of the SPRINT and the SPARTAN intercept events.63 Figure 1-4 depicts the complex PRESS facilities in 1969.

By the early 1970s considerable confidence was expressed in the ability to successfully model reentry phenomena, based on PRESS and related data, and when integrated with the laboratory and theoretical work on reentry physics under DEFENDER.66 Because of the progressively higher cost of reentry tests there was (and is) a major economic payoff to a successful reentry modelling effort However, there were also qualifications to such statements as they related to defensive discrimination.67 The BTL history also expresses some skepticism about the then current theoretical extrapolations, and some frustration due to the lack of threat radar signature data available to them to design their SAFEGUARD system.68

Figure 1-4. PRESS Instrumentation - 1969

After the transfer of most of DEFENDER, ARPA formed its Strategic Technology Office (STO) which continued to support optical and IR research using the PRESS aircraft, until the early 1970s.69 This research provided much of the the basis for sensor developments later undertaken by SDL The PRESS ground-based optical and IR systems went to KREMS, and operated until 1972 with some changes. The Army began to install a new generation of ground-based optical instrumentation, emphasizing IR and active laser systems at KREMS in 1973. The TRADEX Optical Adjunct (TOAD), an optical telescope boresighted with TRADEX and featuring a CCD focal plane array, was installed in about 1980. TOAD images RVs against a star background, enabling highly accurate angular measurements.70 The AOA (Airborne Optical Adjunct) work under SDI has also revived interest in the possibilities of direct use of aircraft as sensor platforms for BMD systems.

Figure 1-5 outlines the history of the PRESS and KREMS optical systems to 1980. Figure 1-5 also shows the current KREMS instrumentation system, including a local-area network intercomputer communication system. In the early 1970s ALTAIR was modified to simulate the SENTINEL-SAFEGUARD system's PAR radar, since the PAR, then being constructed near Grand Forks, S.D., could not observe any test reentries. In the mid-1970s the Air Force expressed a need for a radar sensor in approximately the Kwajalein geographic location for their SPADATS system, in order to deal with launches of satellites from the USSR or China. ALTAIR demonstrated related capabilities in the late 1970s and was modified soon afterwards for both low altitude and deep space satellite observations. In 1981 ALTAIR began SPADATS operations on a round-the-clock basis.71 TRADEX, operating in a new pulse-compression mode, also backs up ALTAIR for spacetrack capabilities. TRADEX also serves as an illuminator for the new precision, multistatic reentry tracking system at KREMS.72

In the mid-1970s, the Army's SAFEGUARD program was terminated. However, a Hard Site Defense System, oriented to defense of ballistic missile launch sites was later designed and, in part, constructed and tested by the Army at the Kwajalein test site.

Figure 1-5. The KREMS Instrumentation Network (From Lincoln Laboratory Journal, op. cit.)

ALCOR has now been upgraded to routinely generate two-dimensional images of objects in orbit, in support of the Air Force's SOI (Space Orbit Identification) activities. Its bandwidth also allowed it to track beacons in RVs. A Lincoln-designed millimeter wave radar, to achieve higher resolution, is the latest addition to KREMS.

KREMS is now the major part of the national R&D facility, operated by the Army's Strategic Defense command, and serving all Service and SDI needs for measurements of RVs and BMD. A particularly good, if somewhat dated, description of its value and activities was given by the Army BMD commander in 1979.73

The BMD Program Manager is also responsible for the operation of Kwajalein Missile Range (KMR), a national range. KMR is not dedicated solely to the support of BMD; it is the major test range for our strategic missile force, offensive and defensive. KMR is unique in two major respects; first the unique quality of the data collected by its highly accurate sensors is essential to the successful development of the new generations of strategic offensive missiles (e.g., MX and TRIDENT II) and second, it provides unique opportunities for coordination, and cooperation between the offensive and defensive technical communities. Virtually all ICBMs fired into KMR serve both the offensive and defensive communities for data collection.
Major fiscal year 1980 test programs at KMR include:
The Advanced Ballistic Reentry Systems (ABRES) test of RV material characteristics, penetration aids, arming and fuzing technology, and maneuvering RV design.
The Minuteman development tests of Special Test Missiles and Production Verification Missiles to evaluate modifications and improvements to the Air Force reentry systems.
The Strategic Air Command (SAC) tests of Minuteman II and III missiles into KMR to provide training for SAC crews and evaluation of weapon system performance. Selected test vehicles have additional data requirements in support of offensive system development objectives.
The BMD Advanced Technology Center Detection, Designation and Discrimination Program, which utilizes the Kiernan Reentry Measurement Site radars (Tradex, Altair and Alcor) to provide the primary source of techniques.
The Systems Technology Test Facility on Meck Island to support evaluation of BMD components for potential application to future BMD systems.
An evaluation of the effectiveness of the ALTAIR radar to meet Air Force Aerospace Defense Command requirements for collecting data was successfully completed in fiscal year 1978. Full time support of ADC requirements is under consideration at this time.
Range planning for the following future testing will be accomplished in fiscal year 1980.
Homing Overlay Experiment tracking scenarios. Interceptor Technology Tested Program.
Tracking analysis and miss distance measurement techniques for Space Defense Program.
Testing to examine the technology required for non-nuclear kill of reentry vehicles.
The importance of KMR to the success of these and other test programs cannot be overemphasized. The U.S. possesses no comparable capability to collect exo-atmospheric signature data, record missile reentry phenomena, provide terminal trajectory and impact data, record missile reentry phenomena, provide terminal trajectory and impact data, recover reentry vehicles when required, and transmit near real-time data to the mission sponsors. The instrumentation required is extensive; moreover, the data provided by these instruments must be of the highest quality. High confidence in our test data leads to high confidence in our missile development programs and ultimately in our operational capabilities.
The collection of our offensive and defensive test activities at KMR is particularly beneficial. In the process of testing our offensive systems, the BMD Program takes full advantage of the opportunity to test new BMD technologies and components against the most sophisticated targets available. The result is the mutual accomplishment of test objectives with a minimum of missile firings and a continuous interchange of data between our offensive and defensive development programs.

Recent steps to further upgrade KREMS for SDI are described in a recent issue of the Lincoln Laboratory Journal,14 and of IEEE's Spectrum.15 The SDI plans for the Kwajalein site also include a supercomputer for range control, and construction of a new generation phased array radar (GBR-X or GSTS) for early acquisition, tracking and discrimination of RVs, and guidance of exo- and endo-atmospheric, interceptors on the site of one of the radar foundations built by BTL in the early 1970s. Incorporating solid state technology, GBR-X is to operate in the microwave frequency range, desired in the late 1950s but then considered economically impractical.


DEFENDER had the objective of doing advanced research relating to BMD and its penetration. A "map" of needed R&D had been provided by earlier studies, and an efficient start for ARPA's work was due in part to the fact that some of the participants in these studies were key players in the early DEFENDER project It was clear from the beginning of DEFENDER that field measurements of ICBM reentry would play a major, if not decisive, role for decisions about the continued credibility of the U.S. deterrent against Soviet ABM efforts, and about the practicality of a U.S. BMD deployment PRESS was the ARPA response to the need to do this kind of high quality measurements. PRESS began as an ARPA initiative, but the continuing participation of a major high quality nonprofit laboratory was a very important factor because of the complexity of the measurements and the key role that these measurements would play. Lincoln at this time was "available" because its BMEWS job was done, but was reluctant at first due to the politics involved in being an Air Force contractor.

A key decision was made by H York as DDR&E to combine assets, the Air Force ICBM shots and the Army's ABM R&D efforts, at Kwajalein atoll. ARPA made a similar key decision to take advantage of this combination, which would mean that the measurements made by the PRESS sensors could be provided equally to the offensive and defensive side.

The early ARPA measurements of reentry made before PRESS primarily with the DAMP ship indicated that discrimination of RVs was difficult and helped toward the national decision not to deploy ZEUS. However, the major factor in this decision was probably the NIKE ZEUS inability to handle multiple RVs. NIKE X was the follow-on option recommended by Dr. J. Ruina, then ARPA director, and assumed that atmospheric filtering could play a key role in simplifying the discrimination problem, at the expense of compressing the time available for action, and so requiring a very high acceleration missile. This early judgement was proved correct by subsequent intensive measurements made by PRESS, and also by BTL. The TRADEX radar and the correlated optical and IR measurement systems were the "workhorse" of this period. BTL recognized the value of the PRESS data and used it for their BMD systems effort. An increase in bandwidth of the NIKE ZEUS target tracking radar (TTR) was partly paid for by ARPA, and there seems to have been some impact of the coherent PRESS radar data on the NIKE X system design. PRESS data also influenced the ADAR effort under DEFENDER, which in turn influenced the later Army BMD system designs.

From about the time of the NIKE X decision, the priority of the PRESS effort seems to have been on the offensive, penetration problem. ALTAIR, the second PRESS radar, was originally designed to mimic the Soviet ABM radars. ALCOR, on the other hand, seems to have been designed largely to explore the possibilities the highest practicable resolution instrument could offer for BMD discrimination. Both ALTAIR and ALCOR were begun under ARPA, but were not used until after the transfer of DEFENDER. The value of TRADEX, ALTAIR, and ALCOR is indicated by their continued use today. These systems, upgraded in several ways and linked in a computer network, are the core of the National Kwajalein Test Site (KTS) facility and now part of the Army's Advanced Technology Center, and are used by the Air Force as part of their operational SPADATS systems and for SOI.

Optical sensors, after receiving initial emphasis, seem to have been relegated to a secondary role during the PRESS period. However, the PRESS optical (and IR) sensor systems did not all go to the Army in the DEFENDER transfer. ARPA, STO, kept the airborne sensors optical development and measurements, as well as the AMOS facility, looking to the future possibilities of exoatmospheric discrimination from an elevated platform. These possibilities have been followed up in later Army and SDI programs.

The transfer of DEFENDER seems to have been a "top down" decision of Dr. J. Foster, then DDR&E, in view of the DoD decision to deploy "the best available BMD system" and the subsidence of inter-Service rivalry over the years. By the time of transfer the objectives of "keeping both offensive and defensive sides honest," setting up a high quality scientific effort in the area, and acting as competition to improve the quality of the Army work had been accomplished. Key tools to carry out further research were in place. These tools included modeling, which integrated theory and laboratory reentry physics with PRESS results, to allow more cost-effective design of expensive reentry tests, and to lend assurance to the major decisions about deployment of BMD.76 Despite these accomplishments, apparently there were some strong feelings, at the time of DEFENDER'S transfer, that there was considerable research yet to do and that ARPA should have remained in charge.77 Some of this research was continued under ARPA's STO, transferred in the early 1980s to the SDI R&D program.

ARPA expenditures for PRESS from project records are about $200 million. The Army and SDI have spent nearly $1 billion in subsequent R&D and upgrading efforts at the KREMS follow-on facility at Roi-Namur. The Air Force had spent over $1 billion on penetration aids by 1970. Typical complex reentry tests now cost over $100 million each. It is difficult to estimate the savings due to the ability to reduce the numbers of ICBM tests required, the negative decisions not to deploy a BMD system, and to put a dollar figure on the positive credibility assurance provided to our deterrent systems.


1 High-level studies of the feasibility of what were eventually called "penetration aids" included those conducted under the Gaither Committee (in 1957) and, a little later, by the DoD Reentry Body Identification Group and by a special panel of PSAC. Many of the same people participated in all these studies, which were chaired by W. Bradley, who later joined and IDA'S ARPA Support Group. "The ABM Debate," by ER. Jayne. MIT thesis, 1969, p. 452, and H. York, "Multiple Warhead Missiles," in Scientific American, Vol 29, Nov. 1973, p. 2004. Earlier Service Studies went back to the early 1950s.

2 According to Gen. Goodpaster, Special Assistant to President Eisenhower, this was the president's primary motif in establishing ARPA. Discussion with Gen. Goodpaster, 4/88.

3 Hearings before Defense Subcommittee on Defense Appropriations, for 1959 85th Congress, 2nd session, statement of R. Johnson, p. 292.

4 DoD directive 512933, Dec 30,1959.

5 R. Johnson, op. cit. pp. 320 and 338. ARPA was also given the Air Force's 117L Satellite Program, which it returned, modified, to the Air Force. The Air Force and Navy ballistic missile efforts, less controversial, were not given to ARPA.

6 H. Yak, Does Strategic Defense Breed Offense, Harvard University Press, 1986, p. 13.

7 ARPA funded some of the field experiments in the Pacific Nuclear tests in 1958 and 1962.

8. A.O.'s 5 of 4/58, and 6 of 6/58, included many efforts following up on the Bradley recommendations in such scenarios. Cf. also Richard J. Barber Associates, History of the Advanced Research Projects Agency, 1958-1975, NHS 1975. p. ID-55.

9 Some work in these areas had been going on since the mid-1950s.

10 DAMP, RCA brochure (UNCLASSIFIED) 1960. By 1961 DAMP included a data measurement analysis laboratory at Moorestown, NJ. Early funding was provided by A.O.'s 51 of 12/58 and 127 of 1/60; also discussion with A. Rubenstein, IDA 12/87.

11 ARPA BMD Technology Program Review. IDA-ARPA TR 59-8. Aug. 1959 (declassified), p. 13.

12 A review of radar measurements and facilities to August 1960 was given by R. Leadabrand of SRI and of IR and Optical Measurements by M. Nagel of AFCRL, in an ARPA review of project DEFENDER for the DDR&E, Aug. 1960 (declassified).

13 Richard J. Barber Associates op. cit p III-55. This first approach to Lincoln was apparently made in May 1958. Earlier, Lincoln had finished R&D for design of the BMEWS radar system for the Air Force and did not yet have another major project to replace it.

14 J.S. Shortal, A New Dimension: Wallops Island Test Range, the First 15 Years, NASA Reference, publication 1028, Dec. 1978, p. 538; and discussion with L. Sullivan, Lincoln Labs, 12/89.

15 A. Rubenstein, discussion op. cit. Earlier shipboard observations had been made by the Army's Operation GASLIGHT, cf.. "Missiles & Rockets," July 14,1958, p. 14.

16 E.g., A.O.114 of 11/59.

17 A.O .236 of 6/61 provided explicitly for BAMIRAC. Earlier related efforts and the AMRAC meetings had been funded by ARPA in 1959 under A.O.'s 6 and 30.

18 ABM Project History, Bell Telephone Laboratories, Oct 1975, pp. 1-32,1-46, and 1-50.

19 Part of the original ARPA motif was to help "backfit," if possible, improvements into NIKE ZEUS, cf. testimony of H. York in DoD Appropriations Hearing for FY1959, House of Representatives, 85th Congress, 2nd Session, p. 257.

20 BTL states, however, that nuclear effects were not considered in the design of NIKE ZEUS, not having been specified by the Army. BTL, op. cit., p. M9.

21 An ARPA-supported comprehensive study of "blackout" by IDA in 1965, using this data, decisively affected the choice of frequencies of NIKE X. See, e.g., BTL History, op. cit., p. 1-44.

22 "KREMS, The History of the Kiernan Reentry Measurements Site," by M.D. Holtcamp, U.S. Army BMDSC, Huntsville, 1980, p. 18. The "loan" was typical for the ARPA's IDA support staff at the time.

23 A. Grobecker, ARPA, 1959, BMD Technology Program Review, op. cit., p. 99.

24 A.O. 49 of 12/58. TRADEX ($38.5 million).

25 SAMSO Chronology, 1954-79, Air Force Systems Command Space Division, Chief of Staff, History Office. 1980. pp 52 and 59.

26 G. Kistiakowsky, A Scientist at the White House, Harvard 1977, p. 319.323. and 327.

27 H. York, Making Weapons, Talking Peace, Basic Books, 1987, p. 177-8. Somewhat later, however, some (Air Force) IRBM shots from Johnson did occur in the Kwajalein area.

28 Unsuccessful attempts were made to locate PRESS facilities in the island of Kwajalein itself. AO 110 of 10/59, Project Press Roi Namur Facility, also AO 121 of 12/59.

29 Apparently there was also a delay of about 1 year between the decision to go ahead with TRADEX and the decision of its frequency band. The first recommendation for TRADEX, Nov. 1958, was for UHF, despite the nuclear effects data from HARDTACK, which showed significant absorption at UHF. L-band was eventually added to UHF for the first version of TRADEX. A. Grobecker, IDA TE 184, Oct 1959 (CLASSIFIED).

30 E. Michael Papa, Historical Chronology of the Electronics System Division (ESD), 1947-86 History Office, Air Force ESD. Hanscom AFB, Bedford, MA, Oct 1987, p. 6.

31 Computer control has taken place gradually, cf. Hohcamp, op. cit, p. 72, and discussion with Gen. K. Cooper (Ret), 6/90.

32 Also, there was dissatisfaction in ARPA with the rate of progress on PINCUSHION. Discussion with 4 A. Rubenstein, 5/90.

33 Holicamp, op. cit., p. 32,

34 TRADEX current specifications are given in K, Roth, et al, "The Kiernan Reentry Measurements System at Kwajalein AFB," Lincoln Laboratory Journal, Summer 1989, Vol. 2, No. 2, p. 255.

33 Discussion with Dr. M. Baiser, 9/89. Lincoln work related on reentry physics, however, was substantial at the time. Cf., e.g., C. McLain, "A Study on General Recommendations for Experimental Held Measurements," Project DEFENDER, May 1961 (UNCLASSIFIED).

36 A.O.127 of 1/60. "PRESS Aircraft"

37 C. McLain Op. Cit.

31 This apparently took place after the cancellation of NIKE ZEUS, in 1963. when the BTL RMP program was expanded in support of NIKE X. BTL, op. cit. p. 1-41. It was paid for in part by ARPA. A.O.702 of 3/65. "Modification of NIKE TTR."

39 Apparently, about $1 billion was spent for penetration aids, etc., between 1962-68. Cf., A.C. Enthoven and W.K. Smith. How Much is Enough, Harper. 1972. p. 190.

40 About this time ARPA also conducted a comprehensive study in this area for WSEG. PENAIDS are discussed more fully in Chapter IV of this volume.

41 Apparently the inspiration for Pen X came from the then Assistant DDR&E for Defensive Systems, Dan Fink. Discussion with BGen R. Duffy (Ret). 3/90. The MIRV economics is discussed in All in a Life Time, by I. Getting, Vantage Books, 1989, p. 479.

42 Jayne, op. cit., p. 173.

43 Jayne, op. cit., and p. 185. See also "Strategic Warfare." by Daniel J. Fink, Science and Technology, Oct 1968, p. 64. Several RVs had been tested, but penetration aids, such as low observability, required tradeoffs. High "Beta" RVs were assumed to have low-observable geometry. The first ABRES flight test apparently took place on the AMR in 1963. Cf., SAMSO chronology, ibid., p. 120. The available data from DAMP, PRESS and BTL were reviewed in the IDA Intercept X Study, in 1962, which provided some input to the NIKE ZEUS decision.

44 BTL, op. cit, p. 2-15. Until about 1964, penetration aids were apparently mainly "on paper." D. Fink, op. cit

45 BTL, op. cit, p. 3-7.

46 Ruina had previously been assistant to DDR&E for Air and Missile Defense. His briefing on NIKE X was given to PSAC and apparently to the President directly, Jane's, op. ciL, p. 179.

47 BTL, op. cit, p. 2-1, and J. Ruina, op. cit

48 Cf. Chapter VI of Vol 1 of this study

49 BTL, op. cit, p. 10-1.

50 Apparently Sec. of Defense McNamara had argued against ABM deployment partly due to the absence of such data, but a while later argued for a test ban on the grounds that the uncertainty did not outweigh the general advantages of a test ban. Later ABM deployments, it was agreed, would involve radar frequencies which could "see through," and a distribution of radars which could "see around" the nuclear effects.

51 AO 310 of 2/62, STARFISH

52 BTL, op. cit., p. 2-15.

53 AO 648 of 12/64, ARPA-Army Agreement on RV Measurements Programs.

54 BTL, op. cit.

55 Jane's, op. cit., p. 257. The NIKE ZEUS and NIKE X radars did not operate at VHF. However, apparently driven by considerations of practicality and cost of high power tubes, for a while there was serious consideration of VHF for the later U.S. BMD systems. BTL History, op. cit, p. 8-10.

56 Hottcamp, op. cit, p. 73.

57 AO. 668 of 2/65, PRESS UHF/VHF Radar.

58 There were earlier ARPA efforts to explore approaches to a wide bandwidth synthetic spectrum radar (AO 145 of 5/60). Cornell Aero Labs., a BTL subcontractor, had also pointed out the value of short pulse lengths. Lincoln later upgraded the bandwidth of its HAYSTACK radar to improve its SOI (Space Object Identification) imaging capability.

59 The ADAR studies began under the blanket AO 498, of 7/63 to Lincoln, for "discrimination studies " Other aspects of the ARPA hard point defense concept included the HAPDAR low cost, hardened phased array radar, and the HIBEX missile. See Chapter III. of this volume.

60 Cf„ AO 254 of 8/16 and AO 379 of 6/62.

61 See e.g. "BMD Discrimination Study," IDA/IASON Study S-298 (CLASSIFIED) 1966. At about the same time, the Pen X and other studies of the utility of penetration aids versus MIRVs were made, favoring the latter.

62 Cf. Hollcamp, op. dt, p. 44-5, and Richard J. Barber, History, op. cit. pp. VII-11, VII-38 and Vm-29.

63 The renaming of the facility was also due to Gen. Betts, Holtcamp, op. ciL, p. 46. Apparently Lincoln also had an internal debate about this time as to whether continued PRESS-type responsibility was compatible with the laboratory's research mission. M. Baiser, op. cit.

64 "Ballistic Missile Defense Testing in the Pacific: 1960-1976," by CA. Warren, Bell Laboratories Record, 1977, p. 204.

65 Cf., e.g., "Radar Reentry Data," by L. Rechtin (Lincoln) and T. Philips (BTL) in Journal of Defense Research, VoL 2B, 3,1970, p. 85 (CLASSIFIED), and (regarding SPARTAN) BTL History, op. cit. p. 5-37.

66 Cf., e.g„ CE McLain, "State of the Art of Reentry Physics," Journal of Defense Research, Vol 2A, No. 1,1970, p. 2. (CLASSIFIED), and Richard J. Barber, History, quoting Dr. C. Herzfeld.

67 McClain, op. cit, p. 5.

68 BTL History, op. cit, Chapter III-7, states that the necessary intelligence information could have been gathered, but wasn't.

69 Holtcamp, op. cit., p. 79.

70 Ibid.

71 Lincoln Laboratory Journal, op. cit., p. 259.

72 Ibid, p. 262.

73 Testimony of MG Stewart C. Meyer, Defense Authorization Hearing for FY 1980, 96th Congress, 1st Session, pp. 314-15.

74 Lincoln Laboratory Journal, op. cit

75 "Kwajalein's New Role; Radar for SDI," by Glenn Zorpeue, IEEE Spectrum, March 1989, p. 64. This article also outlines some of the current operations at KTS.

76 These tests, currently, can require several years preparation and intensive rehearsals, costing over $100 million each, cf., Lincoln Laboratory Journal, op. cit., p. 252.

77 These feelings are described in Richard J. Barber, op. cit., pp. VII-11-12.