Missile Detection and Defense
The Soviet ICBM threat dramatically changed U.S. priorities to building detection and defensive capabilities against ballistic missile attack. Although Sputnik shocked the national psyche, the potential threat of intercontinental ballistic missiles had long been anticipated. Since the German V-2 campaign against England towards the end of World War II, military planners had been working with scientists and engineers to develop an antiballistic missile strategy.
Before the advent of the SS-6 Sapwood and Sputnik, both the Army and the Air Force had been conducting research and development programs leading to an antiballistic missile. The Air Force program, called "Project Wizard," was conceptual in nature. Project Wizard spent millions of dollars in various research labs to develop new technologies to counter the enemy threat. In contrast, the Army program, called "Nike Zeus," was more hardware oriented, building on technology of the earlier Nike Ajax and Nike Hercules antiaircraft missile programs.
In 1958, in the wake of Sputnik, President Eisenhower directed the cancellation of Project Wizard in favor of the Army Nike Zeus program. However, to defend against an attack, the United States needed the capability to detect an attack. Americans feared a nuclear Pearl Harbor, where without warning, nuclear bombs could drop from space, devastating American cities and crippling the military's ability to launch a counterattack. Without the means to defend against such an attack, Americans could only hope that the threat of massive retaliation would deter the Soviet Union from launching such a strike. Early warning would be critical to prepare the nation for the initial blow and allow SAC bombers to get off the ground.
Congress quickly approved funding to construct a Ballistic Missile Early Warning System (BMEWS). Radio Corporation of America (RCA) would develop and build theAN/FPS-49 tracking radars, GE and MIT would design and construct the AN/FPS-50 detection radars, and Western Electric would build the communication systems to connect the radars with command centers. Construction began immediately in the summer of 1958.
BMEWS required building installations at three locations to cover possible flight paths of missiles launched from the Soviet Union. Site I at Thule, Greenland, would host both AN/FPS-49 and AN/FPS-50 radars and receive top construction priority. Providing coverage for most missile approaches from the Eurasian landmass, the Thule site reached initial operating capability in October 1960. Clear, Alaska was selected for Site 11to provide warning against missiles launched from the far eastern Siberia region. Initially hosting only AN/FPS-50 detection radars, the Alaskan site began operating in late1961. Site III, at Fylingdale Moor, Yorkshire, England, was operational in September1963. At Fylingdale Moor, AN/FPS-49 tracking radars provided coverage of ICBMs launched at the United States from the far western Soviet Union and provided an alert for Europeans if the Soviets launched intermediate range missiles at targets in western Europe. 67
Construction at the ICBM detection station at Clear began in August 1958. Located eighty miles southwest of Fairbanks, the station consisted of dormitories, administrative buildings, storage warehouses, recreational facilities, radar buildings, transmitter and computer buildings, fuel facilities, and three huge fence antenna components of theAN/FPS-50.
Designed by GE and MIT's Lincoln Laboratory, the three fixed-in-place fence antennas stood 165 feet tall and 400 feet wide. These curved arrays sent two fan-shaped beams at differing angles beyond the earth's atmosphere. When an object passed through the lower-angled beam, the reflected radar pulses were picked up by supersensitive antennas and passed on to computers that determined the object's position and velocity. When objects passed through the higher -angled second beam, computers received additional information to determine trajectory, speed, impact point, impact time, and launch point. In 1966 a tracking radar was added to the site when Clear received an updated version of the AN/FPS-49. Designated as the AN/FPS-92, this tracking radar featured a movable antenna that locked onto objects identified by the detection radar. This provided additional data to NORAD headquarters. 68
NORAD received additional contributing sensors. In July 1973, Raytheon won a contract to build a system called "Cobra Dane" on Shemya Island in the Aleutian Islands off the Alaskan coast. Designated as the AN/FPS-108, Cobra Dane replaced AN/FPS- 17 andAN/FPS-80 radars placed at Shemya in the 1960s to track Soviet missile tests and to support the Air Force Space track System. Becoming operational in 1977, Cobra Dane also had a primary mission of monitoring Soviet tests of missiles launched from southwest Russia aimed at the Siberian Kamchatka peninsula. This large, single-faced, phased-array radar was the most powerful ever built. 69
In 1976, the Air Force began operating the Perimeter Acquisition Radar attack Characterization System (PARCS). The story of how the Air Force came to possess this huge, phased-array radar traces its roots back to the 1950s.
In February 1955, the Army contracted Bell Telephone Laboratories to develop an ABM system. This system would be built on the technologies obtained during Nike Ajax and Nike Hercules system development. However, the Nike Zeus system developed by Bell never deployed. Acting on advice that immediate deployment was not technically feasible at an acceptable cost, President Eisenhower decided in May 1959 to maintain Nike Zeus as a research and development program.
By January 1963, the research and development program had evolved into "Nike X" On September 18, 1967, Defense Secretary McNamara acknowledged that ABM defenses could still be overwhelmed by a massive Soviet ICBM attack. However, the emergence of a Chinese nuclear threat could be countered by deploying the Nike X system, renamed the Sentinel, around major metropolitan areas.
On March 14, 1969, the Nixon administration canceled the Sentinel deployment scheme. Instead ABM defense was deployed under the name "Safeguard" to protect America's strategic missile forces. Minuteman missile silos surrounding Grand Forks AFB, North Dakota, and Malmstrom AFB, Montana, would be the first to receive ABM defense. 70
As a result of the 1972 ABM agreement, the United States completed work only at the site north of Grand Forks. Declared operational in 1975, the Grand Forks ABM site, armed with 100 defending missiles, could provide only a limited defense against the hundreds of warheads that the Soviets could employ. Furthermore, nuclear war scenarios foresaw the radar complexes coming under immediate attack, rendering the intercepting missiles useless. Faced with this futile situation, the Army wanted to operate the system for at least a year and then incorporate the lessons learned for a follow-on system. However, Army plans were cut short on October 2, 1975, when Congress voted to deactivate the site within the following year. Eventually the Air Force assumed operations of Safeguard's Perimeter Acquisition Radar (PAR) and redesignated the site as Cavalier Air Force Station. From its North Dakota location, PARCS provided additional polar coverage to support BMEWS. 71
BMEWS, along with additional sensors, gave NORAD the capability to warn the National Command Authority of an attack launched from the Soviet Union. However, the Soviet Union could attempt to circumvent the warning system using different geographical approaches. The Cuban Missile Crisis of the fall of 1962 was one such attempt. The placement of intermediate range ballistic missiles in Cuba illustrated the vulnerability of the United States to an attack along its unprotected southern border. Only after a highs takes showdown between the two superpowers, were the missiles removed.
In the wake of the Cuban Missile Crisis, an AN/FPS-85 long-range phased-array radar was constructed at Eglin AFB in Florida. Designed by Bendix Corporation, the radar consisted of a large square transmitter array placed alongside an octangular receiving array mounted on a large structure facing the Gulf of Mexico. The structure hosting the radar burned in 1965, but was rebuilt and placed back in operation in 1969. This radar also served as the main sensor for the Air Force's Spacetrack System and watched the skies over Cuba and the Gulf. 72
The American triumph of keeping Soviet nuclear launch platforms out of Cuba and at a distance would be short-lived and American defense planners knew it. During the early 1960s, Soviet scientists and engineers worked feverishly to design and build Soviet ballistic missile submarines capable of launching missiles from relatively short distances off America's coastlines. Once again the United States needed the capability to detect incoming missiles to prevent the specter of an atomic sneak attack. In December 1961, the Air Force asked ADC for an evaluation of the capability of FD radars to detect Submarine-Launched Ballistic Missiles (SLBMs). Subsequently, AN/FPS-35 search radars located at Manassas, Virginia, and Benton, Pennsylvania, received modifications and began to be tested during the summer of 1962. During these tests, both radars attempted to track Polaris, Minuteman, Titan, and the Thor-Delta missile launched from Cape Canaveral, Florida. The tests revealed that the AN/FPS-35 had only marginal ability to detect missile launches. 73 However, using AN/FPS-35 or AN/FPS-24 FD radars to detect SLBMs continued to be considered a viable option given the fiscal constraints imposed on ADC.
Another option to detect SLBMs that was favored by ADC was to procure a series of An/FPS-49 radars. One of these units had been operating since 1961 at Moorestown, New Jersey, as the original sensor for the Air Force's Spacetrack System. To ADC's disappointment, a study by the Electronic Systems Division at Hanscom AFB, Massachusetts, revealed that using the Moorestown radar for dual use was infeasible. 74
The long-tem vision of ADC planners foresaw SLBM detection as a collateral mission of the OTB-B radar that was still under development. However, ADC could not wait for a system that still was in the research and development stage. In November 1964, desperate to field at least an interim system to warn the nation of a SLBM attack, ADC sought and received permission from the office of the Secretary of Defense to modify existing SAGE system radars. 75
In the ensuing months, makers of the various SAGE-compatible radar systems submitted proposals on the modifications that would enable their products to detect an object of at least two meters in size, at a range of 750 miles, within six seconds after launching. The radar then would continuously track this object within ten seconds of detection and notify NORAD Combat Operations Center within sixty seconds.
In July 1965, the Air Force selected Avco Corporation for an innovative proposal employing its AN/FPS-26 height-finder radar to detect SLBMs. The modified AN/FPS-26 radar system (redesignated as the AN/FSS-7) was slated for deployment at Point Arena. California; Mount Laguna California; Mount Hebo, Oregon; Charlestown, Maine; Fort Fisher, North Carolina; MacDill AFB, Florida; and Laredo Texas. 76
After years of testing and evaluation, the seven-site SLBM detection system became fully operational in 1971. A year later, twenty percent of the surveillance capability of the AN/FPS-85 located at Eglin AFB, Florida, also became dedicated to search for SLBMs. 77
During the 1970s, the Soviets developed SLBMs that could be launched from greater distances away from the American Coastline. For example, the Soviet Delta I class ballistic missile submarine carried the SS-N-8 missile that had a range of over 4,000 nautical miles. This was beyond the detection capability of either the AN/FSS-7 or the OTH-B radar system being developed. 78 Consequently, the Air Force had to turn to another solution.
The solution was a phased-array warning system to become known as "PAVE PAWS" (Perimeter Acquisition Vehicle Entry Phased-Array Warning System). Originally designed as a two-site system, PAVE PAWS sites were constructed in the late 1970s at Otis AFB, Massachusetts, and Beale AFB, California. From a distance, the PAVE PAWS structure looked like a three-sided pyramid with a flattened top. On the two seaward faces of the pyramid, Raytheon installed the AN/FPS-115 with its phased-array antenna. Thirty meters in diameter and consisting of 2,000 elements, each antenna could detect objects launched as far away as 3,000 miles. The Otis site became operational in 1979and the Beale site became operational a year later.
A contract for two more continental PAVE PAWS sites, was awarded in 1984. AnANfFPS-115 at Robins AFB, Georgia, became operational in 1986 and another unit at Eldorado AFS, Texas, was activated in 1987. Additional AN/FPS-115 PAVE, PAWS radars were installed in the 1990s at BMEWS sites at Thule, Greenland, and Fylingdale Moor, England, to assume the ICBM detection mission. As PAVE PAWS sites in the United States were activated, the older AN/FSS-7 radars were phased out, except for the MacDill AFB site that continued to provide additional coverage over Cuba . 70
Spacetracking and missile detection functions of the former Aerospace Defense Command were assumed by SAC in 1980. Control of these facilities became an Air Force Space Command responsibility with the activation of that command on September 1, 1982.
Continued reading of Searching the Skies:The Legacy of the United States
Cold War Defense Radar Program - http://www.fas.org/nuke/guide/usa/ai..._the_skies.htm