Launch Vehicle: Atlas Centaur
Launches: 9 February 1973 (FLTSATCOM A), 4 May 1979 (FLTSATCOM B), 17 January 1980 (FLTSATCOM C), 30 October 1980 (FLTSATCOM D), 6 August 1981 (FLTSATCOM E)
Total Weight: 4136 pounds at launch, 2216 pounds in orbit
Diameter: 8 feet (30 feet with solar arrays fully deployed)
Height: 4 feet 2 inches (16 feet with antennae)
Systems: One 25 KHz (SHF) fleet broadcast channel, Nine 25 KHz (UHF) fleet relay channels, Twelve 5 KHz (UHF) USAF narrow-band channels, One 500 KHz (UHF) DOD wide-band channel
Receiving band: 292-400 MHz (240-400 MHz from FLTSATCOM C on)
Transmission band: 244-279 MHz (240-400 MHz from FLTSATCOM C on)

The US Navy Fleet Satellite Communications (FLTSATCOM) system was designed to provide worldwide high-priority UHF communications between aircraft, ships, submarines, and ground stations, as well as between the US military services and the presidential command network. The communications subsystem provided more than 30 voice and 12 teletype channels designed to serve small mobile users as well as major centers. The payload of the spacecraft included UHF and SHF communications equipment and antennae. The US Air Force AFSATCOM system was carried aboard these Navy spacecraft, built by the TRW Defense and Space Systems Group (now part of Northrop Grumman).

The basic FLTSATCOM consisted of two stacked hexagonal modules, antennae, and two winglike solar arrays. It had an 18-turn helical UHF receive antenna and a 15-foot deployable parabolic UHF transmit antenna. The solar array provided 1200 watts of power. Axis stabilization was provided by redundant, body-mounted momentum wheels that interacted with monopropellant hydrazine thrusters to stabilize the spacecraft's attitude and point the antennae at the earth's center.