Eglin AFB Site C-6

Eglin AFB Site C-6 is an Air Force Space Command radar station with the AN/FPS-85 phased array radar, associated computer processing system(s), and radar control equipment (e.g., MIT Radar Calibration System in 1996). The entire radar/computer system is located at a receiver/transmitter building and is supported by the site's power plant, fire station, 2 water wells (for 128 people), and other infrastructure for the system to provide observations on space objects for "the Joint Space Operations Center satellite catalogue".

Structures

 * Transmitter/receiver building: The antenna elements are mounted on the inclined faces of the transmitter/receiver building. and within the structure is the remainder of the radar, computer, and crew operations equipment.  By 2012, the computer room had 2 "IBM ES-9000 mainframe computers, two RADAR and Interface Control Equipment cabinets, and two SunSparc workstations."  In the squadron Mission Operations Center, "personnel use a screen with [space] objects assigned numbers, similar to an air traffic control screen."  An attached garage is on the building's east side.
 * Power building: The power building has an electrical generation system (cf. the earlier BMEWS "ELEC PWR PLANT" models AN/FPA-19 and -24.)
 * Fire Station: In 2011, the site's fire station (30.57333°N, -86.21444°W) was added to the USGS's Geographical Names Information System (the transmitter/receiver building is not listed.)
 * Recreation facilities: A softball field and gymnasium are avaiilable.
 * Monitoring station: A nearby monitoring station is used for processing a once-per-second calibration pulse transmitted by the radar.

History
1950s missile testing over the Gulf of Mexico used radar sites on federal land assigned to Eglin AFB (e.g., the Anclote Missile Tracking Annex through 1969 at the mouth of the Anclote River near Tampa, the 1959 Cudjoe Key Missile Tracking Annex, and the Carrabelle Missile Tracking Annex that "transferred from RADC to Eglin AFB" on 1 Ocrober 1962.)  "Following the launching of Sputnik I on 4 October 1957, the Air Force's Missile Test Center at Patrick AFB, Florida, set up·a project to observe and collect data on satellites."

Eglin AFB had its "first satellite tracking facility…operational fall 1957", and the 496L System Program Office formed in early 1959. Bendix Corporation was contracted and built a linear array at their Baltimore facility, followed by a prototype "wideband phased array radar (EPS 46-XW 1)" with IBM computer from Spring 1959 through November 1960. The Bendix AN/FPS-46 Electronically Steerable Array Radar (ESAR) using L-band began transmitting in November 1960 as "the first full-size pencil-beam phased-array radar system." "HQ AFSC decided to give full technical responsibility for the development of a sensor for the 496L Space Track System to RADC…after the Soviet lead in satellite technology in October 1957 and the subsequent failure to locate Explorer XII for six months after it was launched" on August 16, 1961. Gen. J. Toomay was program manager after the phased array program transferred to RADC and based on the Bendix Radio Division's ESAR success, the FPS-85 contract was signed on 2 April 1962.

Site construction
Site C-6 construction began in October 1962 for a system "providing for the possibilities of numerous tube failures by arranging for a large number of people to do replacements" during operations. On 5 November 1964, DDR&E recommended the Site C-6 system be used for submarine-launched ballistic missile detection. Before radar testing planned in May 1965, a 5 January 1965 fire due to arcing that ignitied dielectric material "almost totally destroyed" the transmitter/receiver building and contents (the system was insured.) On 22 June 1965 the Joint Chiefs of Staff directed CONAD to prepare a standby plan to also use Site C-6 computer facilities "as a backup" to the NORAD/ADC Space Defense Center "prior to the availability of the AN/FPS-85."

By December 1965 NORAD decided to use the future Site C-6 radar "for SLBM surveillance on an “on-call” basis" "at the appropriate DEFCON", and the specifications for the Avco 474N SLBM Detection and Warning System contracted 9 December 1965 required the AN/GSQ-89 processing system for networking the Fuzzy-7 mechanical radars to also process Site C-6 data. By June 1966 the Site C-6 system was planned "to have the capability to operate in the SLBM [warning] mode simultaneously with the [space] surveillance and tracking modes". Rebuilding of the "separate faces for transmitting and receiving" began in 1967, with the destroyed analog phase shifters and vacuum tube receivers replaced by low-loss diode phase shifters and transistor receivers.

Space Defense
Eglin Site C-6's squadron of the 9th Aerospace Defense Division activated in September 1968 (now the 20th Space Control Squadron) and after "technical problems"; the site with radar and computer systems was completed in 1968, were turned over to Air Force Systems Command on 20 September 1968, and "became operational in December 1968,

Eglin Site C-6 was assigned to Aerospace Defense Command on 20 December 1968, and the site--using the FORTRAN computer language --became operational during the week of Sunday, 9 February 1969. Site C-6 was the 1971-84 location of the Alternate Space Surveillance Center. In 1972 20% of the site's "surveillance capability…became dedicated to search for SLBMs" (the USAF SLBM Phased Array Radar System was initiated In November 1972 by the JCS while the Army's MSR and PAR phased arrays for missile defense were under construction.)  The FPS-85 was expanded in 1974, and "a scanning program to detect" SLBM warheads was installed in 1975. Alaska's AN/FPS-108 Cobra Dane phased array site was completed in 1976 and from 1979 until 1983, Site C-6 was assigned to Strategic Air Command's Directorate of Space and Missile Warning Systems (SAC/SX)--as were the new PAVE PAWS phased array sites operational in 1980.

Space Command
In 1983 Eglin Site C-6 transferred to Space Command (later renamed Air Force Space Command), and the "FPS-85 assumed a deep space role in November 1988 after receiving a range-extension upgrade enabling integration of many pulses." After a contractor protest was denied in 1993, a "new radar control computer" was installed at the site in 1994 (upgraded software was installed in 1999.) The original central monitoring system that tested for failing transmitter modules was replaced by a PC-based system in March 1994. In 1994 when the "amplifier and mixing functions on the existing transmitters" used six vacuum tubes for each module, Southwest Research Institute was redesigning the transmitters (5 tubes were replaced by solid-state components.) By 1998, the site was providing space surveillance on "38 percent of the near-earth catalogue" of space objects (ESC's "SND C2 SPO was the System Program Office.)  "A complete modernization…of the 1960s signal-processing system was being studied in 1999", and in 2002 Site C-6 was tracking "over 95 percent of all earth satellites daily."  In 2008, the site's squadron won the General Lance W. Lord Award for mission accomplishment (new "3-D modeling software" had been implemented.)  In 2009, the site had been included in a computer model of the February 2009 satellite collision, and GCC Enterprises was contracted for completing "AntiTerrorism and Force Protection Improvements" to the site's infrastructure (perimeter fences, etc.), By 2011 the site's "16 million observations of satellites per year" (rate of 30.4/minute) was "30 percent of the space surveillance network's total workload". A 2012 Sensitive Compartmented Information Facility opened at the site and in 2013, "new operating modes at Cavalier AFS and Eglin AFB [Site C-6 provided] more accuracy" than the 1961 VHF Space Surveillance Fence, which could not detect space objects in low altitude/high eccentricity orbits and was decommissioned by November 2013.

AN/FPS-85
AN/FPS-85 Space Track Radar is a phased array radar at Eglin AFB Site C-6 with a beam steered from 155° to 205° in azimuth and is scanned at 35° elevation. The radar tracks more than 16,000 near-earth and deep-space objects.