With the internet driving a demand for ever larger broadband communications satellites, Arianespace hopes to capitalise on its lead in heavylift launch vehicles.

The internet accounts for up to 50% of all satellite traffic carried today, says Leo Mondale, vice-president of Arianespace's US arm. "It is up to 225 transponders from zero four years ago."

The opening up of the Ka frequency band has resulted in a move to larger satellites. "The physical characteristics of Ka-band mean it is more efficient to fly large satellites - as big as 5.5-6t," says Mondale. As many as 15 large satellites could be launched in the next three years, he says.

Manufacturers are building larger spacecraft, including the already in service 5.2t Boeing (formerly Hughes) 702, and the 6t Alcatel Spacebus 4000 and 7.5t Space Systems/Loral 20.20, which are under development.

With a payload to geostationary orbit of 6.2t, the Ariane 5 is currently the largest launcher commercially available, but Boeing's 6.5t-capacity Delta IV Medium Plus and Lockheed Martin's 8.6t Atlas V Series 500 are due to be available from 2002.

Arianespace, with three Ariane 5 commercial launches under its belt, represents "the path of lowest possible risk", says Mondale, adding: "Everybody is talking to us as a backup." Arianespace has already booked three large broadband satellite launches: one for Telesat Canada and two for Wild-Blue Communications, in which Arianespace has an investment.

ESA has begun an Ariane 5 enhancement programme which will take the vehicle's GTO payload to 8t next year, 10.5t by 2002 and 12t by 2006 - sufficient to launch two large satellites simultaneously.

Boeing is developing the 13.1t-capability Delta IV Heavy, with the first launch scheduled for 2003. While Lockheed Martin will complete qualification of an Atlas V Heavy, it has no plans to offer the vehicle commercially as it does not see a big enough market.

Source: Flight International