Experimental Tactical Communications Satellite
Diameter:
2.81 m (9 ft 3 in)
Overall Height
7.62 m (25 ft)
Weight in orbit
645 kg (1424 lb)
TACSAT I was the largest and most powerful communications satellite at the time when it was launched into synchronous orbit by a Titan IIIC booster 9 February 1969, from Cape Canaveral, Florida. The experimental tactical communications satellite was designed and built by Hughes Aircraft Company, under the direction of the U.S. Air Force Space and Missile Systems Organization, for the Department of Defense.
In October 2000, The Boeing Company acquired Hughes Space and Communications Company.
Two stories high and more than 9 feet (2.8 meters) in diameter, the huge satellite was used by the U.S. Army, Navy, and Air Force to test the feasibility of using synchronous satellites for tactical communications with mobile military field units, aircraft, and ships. TACSAT was taken out of service 16 December 1972, after demonstrating the advantages of this type of satellite communications system.
The first satellite to be spin-stabilized by the Boeing developed Gyrostat, TACSAT carried three antenna systems: an array of five UHF helices, two microwave horns for X band communications, and a biconical horn for telemetry and command. Tactical communications experiments in-orbit were conducted in two frequency bands: the standard military UHF band used for air-ground communications and the SHF portion of the X band set aside for military satellite communications.
Since the satellite's strong signals were picked up by all types of terminals, including those with antennas as small as 1 foot (0.3 meter) in diameter, remotely deployed field units communicated with their headquarters and each other through the satellite. The high RF power transmitted by the spacecraft permitted simultaneous access by many users.
| Apogee motor | None |
|---|---|
| Launch vehicle | Titan IIIC |
| Communications | Two hard-limiting repeaters (UHF and SHF) |
| Transmitter Type | UHF--solid state; SHF--TWT |
| Beacon power | UHF--7.5 watts; SHF--1 watt |
| Receiver type | Tunnel diode |
| Receiver channel bandwidth | 50 kHz to 10 MHz |
| Antenna type | UHF--five element helical array SHF--receive and transmit horns T&C--bicone |
| SGLS telemetry | Two PM transmitters and four PCM multiplex encoders |
| Transmitter frequencies | 2200 to 2300 MHz |
| Transmitter RF power output | 1.0 watt |
| Control system | Two H202 reaction control systems, each with one axial and one radial jet |
| Electrical power | Three 28-cell nickel-cadmium batteries, 6 A-hr per battery |
High resolution image available here
TACSAT dwarfs full scale model of Syncom II, the world's first synchronous altitude communications satellite, launched 26 July 1963.
High resolution image available here
Closeup of satellite antenna system.