The site's land with the 1918 Alaska Railroad was purchased by the Department of the Interior in 1949 for Alaskan Air Command's Clear Air Force Auxiliary Field for use as a Ladd Field gunnery range. Total costs for the planned Thule and Clear BMEWS stations in a May 1958 estimate were ~$800 million—an October 13, 1958, plan for both estimated completion in September 1960. An additional area was appropriated for BMEWS Site II. and BMEWS coverage
Clear Missile Early Warning Station construction began in August 1958 with 700 workers—i.e., a "construction" camp was being erected in September 1958 by "Patti-McDonald and Morrison-Knudsen" next to the railroad Groundbreaking for radar structures was May 1959 and the AN/FPS-50 pedestals were complete by June 2, 1959. In 1959 after the original White Alice Communications System contract, "the next segment of WACS... was series of TD-2 microwave installations to support... two routes linked the Ballistic Missile Early Warning Site at Clear AFB... one going down the southeast coast to the Ketchikan-Seattle submarine cable*, and the other, going east to the Canada–US border through Canada, down to the lower 48" which was Clear's Rearward Communications System to Murphy Dome and the Gold King Creek AFS with data for the Ent AFB CC&DF. Three GE AN/FPS-50 Radar Sets were installed with antenna reflectors that each weigh. The "Building Two" middle transmitter building had the radar control room and room with the Sylvania AN/FSQ-28 Missile Impact Predictor Set. The "Clear Msl Early Warning Stn, Nenana, AK" was assigned to Hanscom Field, Massachusetts, on April 1, 1961, and BMEWS Site II was completed July 1, 1961 Clear transferred to Air Defense Command in November 1961. By mid-1962, BMEWS "quick fixes" for ECCM had been installed at Thule and Clear and by June 30, 1962, Ent AFB integration of BMEWS and SPADATS data was completed. On July 31, 1962, NORAD recommended a tracking radar at 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
USAF missile warning operations
Detachment 2 of the 71st Missile Warning Wing was responsible for operations by civilian contractor personnel until 1964, when Air Force personnel began permanently manning the Tactical Operations Room. In 1966, the last of the 5 BMEWS tracking radars was installed an RCA AN/FPS-92 Radar Set with an diameter antenna housed in a diameter radome. The FPS-92 was an improved tbd AN/FPS-49 Radar Set variant with radome blocks having two high-density 1 millimeter thick skins that cover a 15 centimeter thick Kraft-paper core FPS-92 completion raised the "final construction price" of "the missile warning system at Clear" to $300 million Clear provided emergency shelter for 216 flood refugees during August 1967, the same year many "temporary" buildings were replaced. Clear subsequently provided measurements for a University of Alaska experiment which injected sulfur hexafluoride into the upper atmosphere to see if the Aurora Borealis could be affected. Clear had Bomb Alarm System equipment installed by the time the BAS was accepted on 10 February 1961 In 1975, SECDEF told Congress that Clear would be closed when the Shemya Island and Beale AFB radars became operational. After a Thule radome fire, Clear's FPS-92 radome was replaced in 1981 by first disassembling the tracker, constructing the new radome, and reconstructing the FPS-92. Clear's 1st all-female crew pulled its 1st shift on February 28, 1986 Beginning in 1987, ITT operated and maintained the Clear BMEWS under a USAF Space Command contract and in the 1990s, the Southwest Research Institute upgraded Clear's pulse modulator for the transmitter final-stage power amplifier.
Phased array radar
On April 16, 1998, groundbreaking for installing 1987 AN/FPS-115 PAVE PAWS components from Texas was held at Clear for the more advanced Raytheon AN/FPS-120 with 2500 "solid state transmitter" modules. On December 15, 2000, the FPS-50 and −92 transmissions ceased Clear's FPS-120 began 24-hour operations when Clear's SSPARS Site had Initial Operational Capability on January 31, 2001; the date the entire SSPARS became operational On August 30, 2006, after a transition that began in 2001, the ANG's213th Space Warning Squadron took on the early warning/space surveillance mission. BAE Systems began a 2007 contract for SSPARS maintenance, and the Clear FPS-120 was subsequently upgraded to an AN/FPS-132 Upgraded Early Warning Radar by Boeing Integrated Defense Systems "featuring processor and software improvements to enhance capability."
