Inmarsat has placed a contract with EADS Astrium for the Alphasat I-XL, a telecommunications satellite developed jointly with Thales Alenia Space through the European Space Agency's Advanced Research in Telecommunications Systems programme's €440 million ($651 million) element eight.

At its planned launch in 2012 the 6,000kg (13,200lb) 12kW I-XL, with a 12m (39.3ft) aperture antenna reflector, will be able to handle 750 channels in the L band and has a design lifetime of 15 years. It will operate from 25°, providing services to Africa, Europe, the Middle East and parts of Asia.

Inmarsat expects its investment in the I-XL, including ground segment procurement and launch, to be around €260 million. The telecommunications satellite will support its Broadband Global Area Network service provision for its four existing satellites.

"This is the first major public-private partnership for ESA and it will be the model for our Small GEO programme," says the agency's telecommunications department large platform programme manager, Paul Blythe, referring to the European small geostationary satellites programme for which Germany's OHB-System is prime contractor.

Alphasat I-XL will be the outcome of the Alphasat programme and its development platform Alphabus. Alphasat is a French space agency CNES/ESA initiative to develop a larger European telecom payload for the increased demand in broadband, broadcasting and mobile telecommunications services.

Now Alphabus is in its critical design review phase, to be completed by mid-December. Its protoflight model is to be delivered in 2009. The platform is designed to accommodate up to 190 transponders and has potential mass growth to 9,000kg and 20kW power consumption.

The satellite uses an Astrium UK-developed digital signal processor. The I-XL's payload, which the processor is a part of, is also being built at Astrium's UK sites. The UK payload work has been supported by £50 million ($102 million) from the regional development agencies for east and south-east England and London.

The spacecraft will also test three technical demonstration payloads for ESA, with a fourth under consideration. The confirmed three are an active pixel technology star tracker, a laser communications terminal and a Q-V band transmission monitoring device. The fourth payload is for space environments and effects monitoring.