The AN/FPS-85 is a very large-fixed array radar located at Eglin AFB. Initially designed to track satellites, a software update installed in 1975 enabled the unit to track submarine-launched ballistic missiles, or SLBMs. This became the 20th Space Surveillance Squadron’s primary mission, while space surveillance became secondary. From 1971 to 1984 the 20th Surveillance Squadron served as the Alternate Space Surveillance Center, providing computational support to the Space Surveillance Center at Cheyenne Mountain AS, Colo. If the need arose, the squadron could assume command and control of worldwide SSN.
During the 1980s, the AN/FPS‐85 was the proving ground for development of phased array radars designed specifically for early warning of SLBM attacks. The AN/FPS‐85 can detect, track, and identify up to 200 satellites simultaneously and provides 120-degree azimuth of coverage. Generating a combined output of 32 megawatts, the radar can track an object the size of a basketball at a range of more than 35,000 km. The AN/FPS-85 was the first radar purpose-built for the mission.
AN/FPS-85 (Elgin Phased Array Radar) Technical Data
Contractors: AlliedSignal Inc. (prime contractor for the radar); Bendix Communications Division; IBM Computers; L3Harris (sustainment).
Operator/Location: Mission Delta 2, 20th Space Surveillance Squadron, Eglin AFB, Fla.
IOC: 1968.
Active Systems: One radar.