Intelsat VI

The Intelsat VI series of satellites were the 8th generation of geostationary communications satellites for the Intelsat Corporation. Designed and built by Hughes Aircraft Company (HAC) in 1983-1991, there were five VI-series satellites built: 601, 602, 603, 604, and 605.

The Intelsat VI satellite was designed as a spinning satellite as had previous satellite designs. The main body of the spacecraft was spun at 30 revolutions per minute (rpm) to impart gyroscopic stability to the satellite in the Earth's gravitation field. A section of the spacecraft supporting the communications payload and antenna was de-spun to allow the antenna to point at the desired location on the earth.

The Intelsat VI series combined two design features of previous HAC satellites, larger solar array and wide body design. The HS376 extended power spinner satellite had an extra concentric cylindrical solar array which deployed after launch to increase the power generating capability of the satellite, and allow for a larger communications payload. The U.S Government's Wide-body Spacecraft was a larger diameter satellite designed to be launched by the Space Transportation System (STS, US Space Shuttle). Thus the Intelsat VI satellite were of a wide body spinning design with a larger solar array, due to the deploy-able array. The later HS393 series of satellites also used the wide body and extended solar array design.

This resulted in a spacecraft that was 3.6 meters (11 ft 10 in) in diameter and approximately 5.2 m (17 ft 1 in) tall as configured for launch on an Ariane 4 rocket. When the spacecraft had arrived at its assigned orbital location, the concentric solar array would be extended (deployed), along with deployment of the communications antenna. The spacecraft would then be 11.7 m (38 ft 5 in) in length.

The Intelsat VI series of satellite were designed to be launched by either Ariane 4 rockets or the U.S. Space Shuttle.

A liquid bi-propellant propulsion subsystem was used on the Intelsat VI series satellites, and used nitrogen tetra-oxide and mono-methyl hydrazine. Four radial thrusters, rated at 22 newtons (N) (5 lbf) are used for east-west station-keeping, and spin-up/spin-down control. Two 22 N axial mounted thrusters provide north-south station-keeping and attitude control. Two 490 N (110 lbf) apogee thrusters were used to provide the apogee boost to the satellite and support re-orientation maneuvers.

The solar array on the Intelsat VI was sized to provide about 2600 watts of power at the beginning of the satellites life. The Intelsat VI satellites used nickel hydrogen pressure vessel batteries to support operation when the spacecraft was in eclipse behind the earth.

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