The second Inmarsat-4 satellite, designed and built by EADS Astrium,
Europe’s leading satellite manufacturer, is scheduled for launch on November
5 from a Sea Launch platform in the mid-Pacific. The Inmarsat-4 F2 is the
world’s most sophisticated commercial communications satellite.

Three Inmarsat I-4 spacecraft have been built to support Inmarsat's
Broadband Global Area Network (BGAN), a new service that will deliver
unprecedented voice and broadband data connectivity to mobile users around
the world.


The second giant Inmarsat-4 satellite will be positioned in geostationary
orbit at 53 degrees West longitude. It will enable Inmarsat to address a
wide area covering South America, most of North America, the Atlantic Ocean
and part of the Pacific Ocean. The first satellite launched in March 2005
covers Europe, Africa, the Middle East and Asia, as well as the Indian
Ocean. A third satellite is virtually complete and in stand-by storage. All
three satellites are identical and interchangeable - their coverage is
programmable and can be reconfigured in orbit.


These satellites are based on EADS Astrium's Eurostar E3000 satellite
platform, five of which have entered commercial service since 2004. All
three Inmarsat-4 satellites are equipped with an electric propulsion system.
Their 45m wide  solar array generate 14 kW of electrical power at beginning
of life and the spacecraft weighs approximately 5,987 kg at launch. The main
body is 7 metres high and the unfurlable antenna reflector has a diameter of
about 10 metres. EADS Astrium’s facilities in the UK, Germany, Spain and
France all contributed to the design and manufacture of the highly
innovative spacecraft. The spacecraft will provide continued support for
existing Inmarsat systems and offer additional capacity and performance.
They will also provide the new Broadband Global Area Network service over
the major land masses and a large part of the ocean surface. This will
extend coverage of third generation terrestrial mobile networks such as UMTS
(3G) for telephony, data and high-speed Internet access to laptop-sized
terminals. This will enable business travellers, disaster relief workers,
field based oil workers, journalists, etc to operate a virtual office
anywhere in the satellite footprint. A typical user terminal looking like a
small laptop could receive simultaneous voice and data at 492 Kbps.
In order to support small terminals over the whole area with the high signal
strength required, each satellite can digitally form 228 narrow spot beams.
More power and spectrum can be allocated to certain beams, further enhancing
mission flexibility to cope with the fluctuations in traffic. An on-board
digital signal processor, designed and built in the UK, 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. Frequency
agility and extensive frequency re-use across the beams permit efficient
utilisation of the available channels in the L-band spectrum to provide
increased capacity.


The Inmarsat-4 satellites also feature 19 wide beams and full global
coverage to provide continuity of existing Inmarsat services for maritime,
air and emergency services.  A navigation package extends and enhances the
navigation signals already available on Inmarsat-3 satellites for the air
traffic community.


Antoine Bouvier, CEO of EADS Astrium said: “The Inmarsat-4 satellites are
the most sophisticated commercial communications satellites ever built, and
tangible proof of our ability to design and manufacture advanced and
flexible communications payloads. We are proud of this achievement, and
thank Inmarsat for the confidence they have in EADS Astrium on this
innovative and ambitious programme.”