Okean is a Soviet Earth observation satellite program for the operational monitoring of ocean surfaces (sea surface temperatures, wind speed, sea color, status of ice coverage, cloud coverage and precipitation). In particular, the Okean-O1 spacecraft with their polar orbits provide valuable complementary data on the ice status in the Arctic and Antarctic regions (support of navigation information for ships in the northern latitudes), which are not visible from geostationary meteorological satellites.

The Okean program was initiated in 1976 by the former Soviet Union. In particular, the Yuzhnoye State Design Office of the Ukraine was instrumental in this effort. Launches started in 1979 within the experimental Okean series. Mission objective: a major interest was in the operation of active and passive microwave sensors. Both MW (microwave) sensor types provide an all-weather observation capability.

The simultaneous spectral measurements in several wavelengths provide a means of evaluating the hydro-physical parameters of the sea surface, the meteorological parameters of the atmosphere as well as of the sea surface. The parameters are: sea surface temperature, wind speed at the sea surface boundary, liquid vapor content in clouds, integrated water vapor, etc...