Encyclopedia Astronautica
1981.12.20 - MARECS 1


MARECS-A was a geostationary maritime communications satellite, which formed part of INMARSAT's world-wide maritime communications satellite network. MARECS-A moved to a new position on the geostationary orbit. Old position: 334E. New position: 22.5 E. The Marecs satellites were members of Inmarsat's first generation global maritime communications network. Positioned in geosynchronous orbit at 26 deg W in 1982-1986; 178 deg E in 1986-1991; 20 deg E in 1991-1992; 22 deg E in 1992-1996 As of 1 September 2001 located at 11.08 deg W drifting at 18.839 deg W per day. As of 2007 Mar 9 located at 168.28W drifting at 18.837W degrees per day.

The program began as the experimental Maritime Orbital Test Satellite (Marots) in 1973, but was subsequently changed to an operational system resulting in a name change, a satellite redesign, and delayed development. Marecs is operated by ESA for Inmarsat. Spacecraft: Based on British Aerospace ECS platform.3-axis stabilised to 0.2 deg (pitch, roll) using fully redundant momentum wheels, thrusters, and nutation dampers. Redundant sun sensors provide 0.04 deg knowledge. Two sun-tracking solar arrays provide 955 W (BOL) with 2 NiCd batteries for eclipse power. Hydrazine propulsion system for station-keeping. Payload: Three repeaters: shore-to-ship with 5 MHz bandwidth, ship-to-shore with 6 MHz bandwidth, shore-to-shore with 0.5 MHz bandwidth. These provide 35 two-way voice channels plus search and rescue capabilities. One 2 m diameter L-Band antenna and 2 horns (one transmit, one receive) for 4/6 GHz channels. All antennas have full Earth coverage.

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