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FLTSATCOM Fleet Satellite Communications System

The US Navy's Fleet Satellite Communications System (FLTSATCOM) is a constellation of five operational satellites used by both the Navy and Air Force as well as the presidential command network. The system, with a design life of five years, serves as a secure communications link between the three users. Each satellite has 23 communications channels, 10 of which are used by the Navy for communication between its land forces, ships and aircraft. The Air Force uses 12 of the channels as part of its satellite communications system for command and control of nuclear forces. One channel is reserved for US national command authorities.

FLTSATCOM systems feature a main transmitting antenna that's 11 feet in diameter and surrounded by wire mesh screen. The body itself is hexagonal and is 8 inches wide and 4 feet tail. Two improved satellites recently joined four FLTSATCOM originals in orbit to extend the operation of the system well into the 1990s. The new systems carry an experimental extra-high-frequency package as a testbed for terminals being developed for the Milstar communications system.

The development of FLTSATCOM began in 1972 with the awarding of a development contract to TRW. The five operational satellites currently in orbit were launched on Atlas E boosters between 1978 and 1989 at Cape Canaveral AFS, FL. FLTSATCOM weighs 2,300 pounds in orbit, with solar arrays generating up to 1,540 watts of power. FLTSATCOM is 8 feet in diameter, with a 50 inch high body and a 16-foot diameter main antenna. The primary contractor for FLTSATCOM was TRW Space and Defense Systems Group.

The first three Fleet Satellite Communications (FLTSATCOM) satellites, launched in 1978, 1979 and 1980 are also on backup status, with FLTSATCOM 4 and FLTSATCOM 6, launched in 1980 and 1986 respectively, fully operational. FLTSATCOM 5 was lost in an 26 February 1987 launch vehicle accident, and FLTSATCOM 7 (the last of the series) was be launched on 22 September 1989.(1)

FLTSATCOM satellites -- six have been sucessfully placed into orbit -- are the spaceborne portion of a worldwide Navy, Air Force and Department of Defense system to enable communications between naval aircraft, ships, submarines, ground stations, Strategic Air Command elements and Presidential Command Network.(2)

The FLTSATCOM program is managed by the Space and Naval Warfare Systems Command. The Air Force Space Systems Division, Los Angeles, is responsible for production, launch vehicle/spacecraft integration and tracking and data acquisition. FLTSATCOM spacecraft are built in Redondo Beach, CA, by the Defense and Space Systems Group of TRW, Inc.

Five satellites presently comprise the FLTSATCOM constellation. Two satellites in the planned eight-satellite series were lost -- the Flight 4 spacecraft was damaged during launch in 1981 and did not operate and the Flight 6 spacecraft and launch vehicle were destroyed by an apparent lightning strike during launch in 1987.

Each FLTSATCOM spacecraft has 23 communications channels in the ultra-high and super-high frequency bands. Ten of the channels are used by the Navy for worldwide communications among its land, sea and air forces. Twelve of the channels are used by the Air Force as part of the Air Force Satellite Communications System for command and control nuclear capable forces. A 500 kilohertz channel on the satellite is allotted to National Command Authority.

The ground segment of the fleet satellite system consists of links among designated and mobile users, including most U.S. Navy ships and selected Air Force and Navy aircraft, submarines, global ground stations and presidential command networks. These terminals are being managed and acquired by the individual services.

The final FLTSATCOM spacecraft (designated Flight-8) along with its apogee kick motor, with solid propellant, weighs approximately 5,100 pounds going into transfer orbit.

The Flight-8 spacecraft body is 8 feet in diameter and 22.8 feet high. Main parabolic antenna is 16 feet in diameter with an 80-inch solid center surrounded by a wire mesh screen. Once in orbit, the folded screen is deployed by ground command. A 13.5 foot helical receive antenna, 13-inches in diameter at the base, is mounted outside the edge of the transmit antenna dish. The receive antenna also is folded within the Centaur fairing during launch and deployed by separate ground commands.

Primary electrical power for the Flight-8 spacecraft is provided by two deployable solar array paddles which supply approximately 1,200 watts of power. In addition, three nickel-cadmium batteries, each having 24-sealed, 34-amp-hour cells, provide power during eclipse operations.

With a design life of 5 years, the satellites are three-axis stabilized in geosynchronous orbit, 22,250 nautical miles above the Earth's equator.


References

1. "Last FLTSATCOM Satellite Planned For Launch September 22," Aerospace Daily, 15 September 1989, page 466.

2. Adapted from: NASA, "NASA to Launch Navy Communications Satellite," Release 89-145, 18 September 1989.


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