The Okean series of satellites are all-weather radar oceanographic systems primarily designed to monitor sea-ice conditions in the Arctic Seas. The payload includes a side-looking radar, a scanning microwave radiometer, nadir-viewing microwave spectrometer, optical scanners and a data collection platform. The spacecraft is a stepped cylindrical pressurized bus 3 m high and 1.4 m diameter. The spacecraft is 3-axis stabilized (nadir pointing, aided by a gravity gradient boom), has twin solar arrays spanning 4.82 m and an 11.8 m radar antenna mounted on the Earth-facing base. A primary feature of the Okean-series is direct Automatic Picture Transmission (APT) on 137.4 MHz of imagery to APT stations as well as to foreign users. The on-board recorder has 6.5 minute capacity and permits coverage and transmission of a 470 x 2750 km image by side-looking radar (SLR) and 1930 x 2750 km image by the multispectral scanner during a pass over an APT station. The Okean payload was flown on Cosmos 1500, Cosmos 1602, Cosmos 1766, and Cosmos 1869 (radar failed), as well as Okean-1 and Okean-2. See Karpov, A., "Hydrometeorological, Oceanographic and Earth-Resources Satellite Systems Operated by the U.S.S.R.", Adv Space Res., Vol. 11, No. 3, pp. 183-190, 1991.
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