In its short lifetime, the SEASAT Scanning Multichannel Microwave Radiometer (SMMR) observed the world's oceans for almost 100 days in the summer of 1978. This was done in order to determine sea surface temperature (SST), wind speed at the ocean's surface, rain rate, and the integrated column density of water vapor and liquid water in the atmosphere. These parameters are deduced from measurements of both horizontal and vertical polarizations of radiation at five microwave frequencies from 6.6 to 37 GHz.

SEASAT was a ‘proof of concept’ satellite to determine how accurately microwave sensors could measure important parameters of the oceans. The SST measurements examined so far are encouraging. They have been compared to nearly 100 high-quality surface observations under a variety of conditions and have been found to possess a negligible bias and to be accurate to within 1° over a wide range of values (10°–30°C).