THE GENERAL PRINCIPLES AND BASIC FEATURES OF THE MARITIME MOBILE SATELLITE SERVICE
INMARSAT Space Segment This consists of the satellites and the radio communic ations transponders and telemetry and tracking devices which they carry. Four active satellites some 36,000 km above the equator between them cover the entire Earth 's surface except for the Polar regions. The satellites are in geo-synchronous orbits and always 'see' the same area. Thus there is one satellite for the Pacific Ocean Area , one satellite for the Indian Ocean Area and two satellites for Atlantic Ocean Area coverage . The Space Segment also includes ground control facilities.