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- coordinates 'in ColoradoSite I in GreenlandSite II in Alaska (71st Det 2) Site III in Yorkshire (71st Det 1) on Trinidad in New Jersey (9th Det 3) | ||
The RCA 474L Ballistic Missile Early Warning System (BMEWS, "474L System", Project 474L) was a United States Air Force Cold War system of radar, computer, and communications systems that included ballistic missile detection radars. The network of 12 radars for detecting "a mass ballistic missile attack launched on northern approaches [for] 15 to 25 minutes warning time" also provided Project Space Track satellite data (e.g., about 1/4 of SPADATS observations).
Contents
Background
The Ballistic Missile Early Warning System (BMEWS) was a radar system built by the United States during the Cold War to give early warning of a Russian intercontinental ballistic missile (ICBM) nuclear strike, to allow time for US bombers to get off the ground and land-based US ICBMs to be launched, to reduce the chances that a preemptive strike could destroy US strategic nuclear forces. The shortest (great circle) route for a Russian ICBM attack on North America is across the North Pole, so the first BMEWS facilities were built in the Arctic at Clear Air Force Station in central Alaska, and Site J near Thule Air Force Base, Thule, Greenland. When it became clear in the 1950s that Russia was developing ICBMs, the US was already building an early-warning radar system in the Arctic, the DEW line, but it was designed to detect bombers and didn't have the capability of tracking ICBMs. The challenges of designing a system which could detect and track a massive strike of hundreds of ICBMs was formidable; the time between when a Russian missile would become visible at the horizon and when it would reach its target in the US was less than 20 minutes.
Equipment
BMEWS consisted of two types of radars and various computer and reporting systems to support them. The first type of radar consisted of very large, fixed rectangular partial-parabolic reflectors with two primary feed points. They produced two fan-shaped microwave beams that allowed them to detect targets across a very wide horizontal front at two narrow vertical angles. These were used to provide wide-front coverage of missiles rising into their radar horizon, and by tracking them at two points as they climbed, enough information to determine their rough trajectory. The second type of radar was used for fine tracking of selected targets, and consisted of a very large steerable parabolic reflector under a large radome. These radars provided high-resolution angular and ranging information that was fed to a computer for rapid calculation of the probable impact points of the missile warheads. The systems were upgraded several times over their lifetime, replacing the mechanically scanned systems with phased-array radar that could perform both roles at the same time.
BMEWS equipment included:
To predict when parts "might break down", the contractor also installed RCA 501 computers with 32k "high speed memory", 5-76KC 556 bpi 3/4" tape drives, & 200 track random access LFE drums. The initially-replaced portions of BMEWS included the Ent CC&DF by the Burroughs 425L Missile Warning System at the Cheyenne Mountain Complex (FOC July 1, 1966.) The original Missile Impact Predictors were replaced (IOC on August 31, 1984), and BMEWS systems were entirely replaced by 2001 (e.g., radars were replaced with AN/FPS-120 SSPARS) after Satellite Early Warning Systems had been deployed (e.g., 1961 MIDAS, 1968 Project 949, and 1970 DSP satellites).
Early tests
On June 2, 1955, a General Electric AN/FPS-17 "XW-1" radar at Site IX in Turkey that had been expedited was completed by the US in "proximity to the ballistic missile launch test site at Kapustin Yar in the Soviet Union" for tracking Soviet rockets and "to demonstrate the feasibility of advanced Doppler processing, high-power system components, and computerized tracking needed for BMEWS [sic]".
The first missile tracked was on June 15, and the radar's parabolic reflector was replaced in 1958, and its range was "extended from 1000 to 2000 nautical miles" after the 1957 Gaither Commission identified that because of expected Soviet ICBM development, there would be "little likelihood of SAC's bombers surviving since there was no way to detect an incoming attack until the first warhead landed".
BMEWS' General Operational Requirement 156 was issued on November 7, 1957 (BMEWS was "designed to go with the active portion of the WIZARD system") and on February 4, 1958; the USAF informed Air Defense Command (ADC) that BMEWS was an "all-out program" and the "system has been directed by the President, has the same national priority as the ballistic missile and satellite programs and is being placed on the Department of Defense master urgency list." By July 1958 after NORAD manning began, ADC's 1954 blockhouse for the Ent AFB command center had inadequate floor space; and Ent's "requirement for a ballistic missile defense system display tacility...brought renewed action...for a new command post" (the JCS approved the nuclear bunker on February 11, 1959.).
Planning and development
On January 14, 1958, the US announced its "decision to establish a Ballistic Missile Early Warning System" with Thule to be operational in 1959—total Thule/Clear costs in a May 1958 estimate were ~$800 million (an October 13, 1958, plan for both estimated completion in September 1960.) The Lincoln Laboratory's radar at Millstone Hill, Massachusetts, was built and provided data to a 1958 for "trajectory estimates", e.g., Cape Canaveral missiles, and an "adjunct high-power UHF test facility employed the Millstone transmitter to stress-test the components that were candidates for the operational BMEWS." (A twin of the Millstone Hill radar was dedicated at Saskatchewan's Prince Albert Radar Laboratory on June 6, 1959.) A prototype AN/FPS-43 BMEWS radar completed at Trinidad in 1958 went operational on February 4, 1959, the date of an Atlas IIB firing from Cape Canaveral Launch Complex 11 (lunar reflection was tested January–June 1960). On June 30, 1958, "NORAD emphasized that the BMEWS could not be considered as a self-contained entity separate from the Nike Zeus, or vice versa."
On March 18, 1959, the USAF told the BMEWS Project Office to proceed with an interim facility for the "AICBM control center" with an anti-ICBM C3 computer (e.g., for when the USAF Wizard and/or Army Nike Zeus ABMs became operational), and the basement of the 1954 ADC blockhouse was considered for the interim center. A "satellite prediction computer" could be added to the planned missile warning center if Cheyenne Mountain's "hardened COC slipped considerably beyond January 1962" (tunneling began in June 1961.) In early 1959 for use at Ent in September 1960, a BMEWS display facility with "austere and economical construction with minimum equipment" was planned in an "annex to the current COC building". In late 1959, ARPA opened the 474L System Program Office, and BMEWS' "12th Missile Warning Squadron at Thule…began operating in January 1960." Following a Nike ABM intercept of a test missile, the planned Cheyenne Mountain mission was expanded in August 1960 to "a hardened center from which CINCNORAD would supervise and direct operations against space attack as well as air attack" (NORAD assumed "operational control of all space assets with the formation of" SPADATS in October 1960.) The 1st Aerospace Surveillance and Control Squadron (1st Aero) was activated at Ent AFB on February 14, 1961; and Ent's Federal Building was completed c. 1960-1.
Deployment
Clear AFS construction began in August 1958 with 700 workers (completed July 1, 1961), and Thule Site J construction began by May 18, 1960, with radar pedestals complete by June 2. Thule testing began on May 16, 1960, IOC was on September 30, and the initial operational radar transmission was in October 1960 (initially duplex vacuum tube IBM 709s occupied 2 floors).
On November 24, 1961, an AT&T operator failure at their Black Forest Microwave Station northeast of Colorado Springs caused a BMEWS communications outage to Ent and Offutt (a B-52 near Thule confirmed the site still remained.)
Training for civilian technicians included a February 1961 RCA class in New Jersey for a Tracking Radar Automatic Monitoring class. The "Clear Msl Early Warning Stn, Nenana, AK" was assigned to Hanscom Field, Massachusetts, by the JCA on April 1, 1961. By May 16, 1961, Ent's "War Room at NORAD" had a glass map for plotting aircraft and had a "map [that] lights up" to show multiple impact ellipses and times "before the huge missile[s] would burst" (separate from Ent's BMEWS CC&DF building, the 2 story blockhouse had a war room with, left of the main NORAD region display, a BMEWS display map and "threat summary display" with a count of incoming missiles.) The Trinidad Test Site transferred from Rome AFB to Patrick AFB on July 1, 1961 (closed as "Trinidad Air Station" in 1971) and the same month, the 1st Aero began using Ent's Space Detection and Tracking System (SPADATS) operation center in building P4's annex (Cheyenne Mtn's Space Defense Center became fully operational in 1967.) The BRCS undersea cable was cut "presumably by fishing trawlers" in September, October, and November 1961 (the BMEWS teletype and backup SSB substituted); and in December 1961, Capt. Joseph P. Kaufman was charged "with giving [BMEWS] defense data to ... East German Communists."
BMEWS surveillance wing
The 71st Surveillance Wing, Ballistic Missile Early Warning System, was activated on December 6, 1961 at Ent AFB (renamed 71st Missile Warning Wing on January 1, 1967, at McGuire AFB July 21, 1969 – April 30, 1971). Syracuse's BMEWS Test Facility at GE's High-Power Radar Laboratory became the responsibility of Rome Air Development Center on April 11, 1962 (Syracuse's Eagle Hill Test Annex closed in 1970) and on July 31, 1962, NORAD recommended a tracking radar station at Cape Clear to close the BMEWS gap with Thule for low-angle missiles (vice those with the 15-65 degree angle for which BMEWS was designed.) By mid-1962, BMEWS "quick fixes" for ECCM had been installed at Fylingdales Moor, Thule and Cape Clear AK and by June 30, integration of BMEWS and SPADATS at Ent AFB was completed. During the Cuban Missile Crisis, the Moorestown AN/FPS-49 radar on October 24 was "withdrawn from SPADATS and realigned to provide missile surveillance over Cuba." 1962 "strikes and walkouts" delayed Fylingdales' planned completion from March until September 1963 and on November 7, the Pentagon BMEWS display subsytem installation was complete. At the end of 1962, NORAD was "concerned over BMEWS' virtual inability to detect objects beyond a range of 1500 nautical miles." The Moorestown FPS-49 completed a BMEWS "signature analysis program" on scale models by January 1963.
Air Defense Command
Operations transferred from civilian contractors (RCA Government Services) to ADC on January 5, 1962 (renamed Aerospace Defense Command in 1968.) Fylingdales became operational on September 17, 1963, and Site III transferred to RAF Fighter Command on January 15, 1964 (after becoming operational on September 17, 1963.) Remaining BMEWS development responsibilities transferred to the "Space Track SPO (496L)" when the BMEWS SPO closed on February 14, 1964—e.g., the AN/FPS-92 with "66-inch panels" was added to Clear in 1966 (last of the 5 tracking radars), and in 1967, BMEWS modification testing was complete on May 15, when the system cost totaled $1.259 billion. In 1968, Ent's 9th Division HQ had a Spacetrack/BMEWS Maintenance Section.
In 1975, SECDEF told Congress that Clear would be closed when Cobra Dane and the Beale AFB PAVE PAWS became operational. By 1976, BMEWS included IBM 7094, CDC 6000, and Honeywell 800 computers.
USAF Space Command
On October 1, 1979, Thule and Clear transferred to Strategic Air Command when ADCOM was broken up then to Space Command in 1982. By 1981 Cheyenne Mountain had been averaging 6,700 messages per hour compiled via sensor inputs from BMEWS, the JSS, the 416N SLBM "Detection and Warning System, COBRA DANE, and PARCS as well as SEWS and PAVE PAWS" for transmission to the NCA. To replace AN/FSQ-28 predictors, a late 1970s plan for processing returns from MIRVs installed in new Missile Impact Predictor computers was complete by September 1984.