Highly sophisticated communications technology
The three Inmarsat-4 satellites were built by Airbus Defence and Space to support Inmarsat’s Broadband Global Area Network (BGAN) services, which deliver unprecedented voice and broadband data connectivity around the world at speeds of up to half-a-megabit per second, to mobile users on land, at sea and in the air.
Each satellite can digitally form more than 200 spot beams. More power and spectrum can be allocated to certain beams to cope with the fluctuations in traffic. An on-board digital signal processor routes the signals to the different beams, acting like a switchboard in the sky: any signal uplink can be routed to any mobile downlink beam and vice versa.
All three satellites are identical and interchangeable – their coverage is programmable and can be reconfigured in orbit. They are based on Airbus Defence and Space’s Eurostar E3000 satellite platform, and equipped with electric propulsion system. Their 45m long solar array generates 14kW of electrical power and the spacecraft launch mass is approximately 5,950kg at launch. The main body is seven metres high and the unfurlable antenna reflector has a diameter of about 10 metres.
The two first Inmarsat-4 satellites were launched in 2005 and the third in 2008, completing the constellation to achieve global coverage.