AN/FPS-85 Spacetrack Radar
Air Force Rome Air Development
Center [RADC] was tasked with engineering responsibility for the
development of a spacetrack radar (AN/FPS-85) and sponsored a
developmental contract with the Bendix Corporation. As the initial
operational application of the phased-array concept, in which a beam from
several transmitters was transmitted without the movement or rotation of
conventional radar, the AN/FPS-85 would be the first phased-array radar
developed to track objects in space.
The Aerospace Defense Command's 14th
Aerospace Force assumed operational control of the AN/FPS-85 Space Track
Radar -- previously designated the Electronically Steerable Array Radar (ESAR)
-- at Eglin AFB in late December 1968. This was the first phased-array
radar system especially designed to detect and track objects in space. The
physical structure of the system was 13 stories high, and the radar
contained 5,134 transmitters and 4,660 receivers and utilized three
computers.
The AN/FPS-85 covers 120 degrees in
azimuth and in excess of 22,000 nautical miles in range. The transmitter
array contains 5,928 transmitter antennas in a 78 x 76 square array and
5,184 transmitter modules installed in a 72 x 72 square array. The
receiver array contains 19,500 receiver antennas and 4,660 receiver
modules.
The AN/FPS-85 building is composed
of the receiver side which is 192 feet long, 143 feet deep, and 143 feet
high. The transmitter side is 126 feet long, 95 feet deep, and 95 feet
high. Total floor space is 250,000 square feet, with 1,250 tons of
structural steel, 1,400 cubic yards of concrete, and a total of 2,500,000
cubic feet in the building.
A fire station is on site and fire
fighting equipment includes a 12.5 ton carbon dioxide storage tank, two
fire vehicles, three water pumps (2 electrical, 1 diesel) which can pump
1500 gallons per minute each, two water tanks (250,000 gallons each) which
can provide two gallons of water for every square foot of floor space,
smoke and heat detectors, and automatic door closures.
Air conditioning equipment includes
three 500-ton water chillers. Electrical prime power is available from
Choctawhatchee Electric Cooperative. There are two 400 KVA uninterruptible
power supplies; system power requirements are approximately 4,000 KW, and
three emergency diesel generators (500 KW and two 400 KW).
The computer room houses five IBM
computers used in mission performance, communication and software
development and testing. Also, two radar interface control equipment
(RICE) cabinets provide a means to interface the mission computers to the
radar.
Communications equipment includes
two Message Distribution Terminals (MDT) and one Mitron magnetic tape
unit. Each MDT terminal has a 486 CPU and two medium speed printers. The
Patch and Test Facility consists of the cryptographic equipment, patch
panels, test equipment, secure voice equipment, Defense Information Agency
Network (DISN) equipment and the Node for the Space Digital Information
Network (SDIN).
Construction of the radar facilities
began in October 1962, at test site C6, about 35 miles east of Eglin Air
Force Base, FL. The testing was scheduled for May 1965, but four months
before, the building and all the equipment were destroyed in a fire caused
by arcing electrical equipment. The Air Force took ownership of the site
in September 1968.
Initially charged with tracking
objects in Earth's orbit, new software installed in 1975 allowed tracking
of submarine launched ballistic missiles. This became the main use of the
AN/FPS-85 though still used to perform space tracking.
The AN/FPS-85 played an active role
in America's space program. From 1971 to 1984, the site was home of the
Alternate Space Surveillance Center. It provided computational support to
the Space Surveillance Center at Cheyenne Mountain AS, CO. If the need
arose, the squadron operating the AN/FPS-85 could assume command and
control for worldwide space track sensors. When that squadron integrated
US Air Force Space Command in the early 1980's, the AN/FPS85 became the
proving ground for the Air Force's phased array radars. The new technology
was used in new radars specifically designed and located for early warning
of SLBM attacks. These PAVE Phased Array Warning System radars assumed
early warning responsibilities away from the Eglin Space Track Radar.
In 1987, the site returned to its
original mission space surveillance. The site underwent a major
transition, allowing Defense Department civilians to staff the majority of
support and maintenance functions, while military people staffed the
command section, orderly room and operations functions.
