Downloaded from NASA Spacelink!
Seasat-A was launched from Vandenberg Air Force Base,
California, on June 26, 1978, by an Atlas-Agena launch vehicle. It
was injected into a near-circular polar orbit with an apogee of 798 km
and a perigee of 775 km.
An Agena, the second stage of the Atlas-Agena launch
vehicle, served as the satellite bus and provided attitude control,
power, guidance, telemetry, and command functions. Attached to the
Agena was a sensor module which carried the payload of five microwave
instruments and their antennas. Together, the two modules were about
21 meters long with a maximum diameter of 1.5 m without appendages
deployed. After burnout of the Agena stage and injection into orbit,
Seasat-A weighed 2300 kg. In orbit the satellite appeared to stand on
end with the sensor and communications antennas pointing toward Earth
and the Agena rocket nozzle and solar panels pointing toward space.
Seasat-A was stabilized by a momentum wheel/horizon sensing system.
Seasat-A was designed to demonstrate techniques for global
monitoring of oceanographic phenomena and features, to provide
oceanographic data, and to determine key features of an operational
ocean-dynamics monitoring system. The major difference between
Seasat-A and previous Earth observation satellites was the use of
active and passive microwave sensors to achieve an all-weather
capability.
After 106 days of returning data, contact with Seasat-A was
lost when a short circuit drained all power from its batteries.