Seasat was the first Earth observation satellite of NASA remote sensing of the oceans. On 27 June 1978 of the 2300 kg satellite with an Atlas Agena D from Vandenberg Air Force Base in a 769 km x 799 km high orbit was started with 108 ° tilt equator. He remained only 105 days operational. Cause the loss of the satellite on October 10, 1978, a short-circuit.
The developed by the Jet Propulsion Laboratory Seasat should demonstrate the suitability of technologies for Earth observation, which had been used until then only for interplanetary space probes. The mission consisted of five experiments: a radar altimeter, a microwave scatterometer, a microwave radiometer, a radiometer in the visible and infrared light, and for the first time in an Earth observation satellites, a synthetic aperture radar (L- band wavelength / frequency: 23, 5 cm / 1.275 GHz) as the main instrument. This Seasat can be seen as paving the way for missions such as TOPEX / Poseidon, Jason or QuikSCAT. An improved version of the radar altimeter was launched on the satellite Geosat.
Seasat discovered among the jungle of Guatemala, the channels that allowed the Maya agriculture to supply its major cities. Seasat was able to demonstrate the waves generated by a submerged submarine with its SAR.