GEO > Geosynchronous > Geostationary
[Source: NASA NSSDC, http://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=1980-074A
GOES 4 was launched in September 1980 and was a NASA-developed, NOAA-operated, geosynchronous, and operational ... spacecraft. The cylindrically shaped spacecraft measured 190.5 cm in diameter and 230 cm in length, exclusive of a magnetometer that extended an additional 83 cm beyond the cylinder shell. The primary structural members were a honeycombed equipment shelf and thrust tube. The VISSR telescope was mounted on the equipment shelf and viewed the Earth through a special aperture in the side of the spacecraft. A support structure extended radially out from the thrust tube and was affixed to the solar panels, which formed the outer walls of the spacecraft and provided the primary source of electrical power. Located in the annulus-shaped space between the thrust tube and the solar panels were stationkeeping and dynamics control equipment, batteries, and most of the SEM equipment. Proper spacecraft attitude and spin rate (approximately 100 rpm) were maintained by two separate sets of jet thrusters mounted around the spacecraft equator and activated by ground command. The spacecraft used both UHF-band and S-band frequencies in its telemetry and command subsystem. A low-power VHF transponder provided telemetry and command during launch and then served as a backup for the primary subsystem once the spacecraft attained orbit.
The spin-stabilized spacecraft carried a visible infrared spin-scan radiometer atmospheric sounder, meteorological data collection and transmission system, space environment monitor, and a biaxial fluxgate magnetometer. It operated at 100 degrees West initially, but replaced GOES 3 at 135 degrees West in March 1981. When GOES 5 VAS experienced a failure on July 30, 1984, GOES 4 was reactivated by NOAA to provide GOES 1 VISSR data relay services to western users.
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