Following the EADS Astrium announcement of its intention to enter the nascent space tourism market Flight took time out at the Paris air show to talk to the project's leader, Astrium chief technical officer Robert Lainé, about the status of the company's space jet design.

According to Lainé, breadboard testing is continuing for the space jet's systems as the search for investors speeds up following initial talks with potential backers in January. Work on the jet began in the third quarter of 2005 and the company has spent "20 man years" on its development with a volunteer technical team.

In 2005 the volunteers examined options including the use of a carrier aircraft, similar to Virgin Galactic's White Knight-SpaceShipOne system, and conventional vertical take-off rockets. But they concluded the spaceplane configuration was the easiest to operate.

Different space jet designs were studied, but the current shape is the outcome of computer simulations and final windtunnel verification work at the German Aerospace Centre's Cologne facility in the last quarter of 2006.

The fuselage will have a high composite content and its moving canards are to aid the vertical climb and have a key role in helping to change the vehicle's descent mode from re-entry to conventional flight. However, Lainé would not comment on whether the canards were derived from the Eurofighter programme.

Reaching 39,300ft (12,000m) with two turbofans, the vehicle's single pilot will fire an EADS Ottobrunn-designed liquid-oxygen, methane rocket motor. The ratio of the vehicle's wet to dry mass is 1.6:1.

Once out of the atmosphere a cold gas reaction control system is used for attitude adjustments, with the gas potentially drawn from residual rocket engine fuel.

Discussions with jet engine providers has convinced Lainé that the turbofans will not be harmed by the harsher environment from 40,000ft to 100km (60 miles) and back. The exposure is expected to be about 5min.

"Thermal inertia keeps the engines warm. It has no time to cool down. We only expect to have to examine possible oil loss," says Lainé, adding that kerosene fuel in the wings is also expected to remain unaffected because of the short duration in a rarefied atmosphere and vacuum.

While on re-entry he expects the thermal flux to raise fuselage surface temperatures to "no more than 125C (257F)", which aluminium can repeatedly cope with.

This re-entry temperature is partially due to the special re-entry profile, which Lainé says is aided by the canards and a centre of gravity that is toward the rear of the vehicle.

Because the re-entry and descent profile is so important it was deliberately excluded from the promotional video - in which the design is taken directly from the space jet's computer-aided design files.

Although the vehicle will land using its turbofans Lainé is pleased with the vehicle's glide performance, another characteristic studied in the DLR windtunnel.

Inside the pressurised cabin the atmospheric pressure is expected to be 600mbar maximum to mitigate against possible depressurisation events that could be made worse by having a 1,000mbar, sea-level, environment.

But he expects that the final cabin environment will have to be "agreed with the regulators". In the USA the Federal Aviation Administration's regulations require cabin atmosphere monitoring and fire-suppression systems to be built into US-operated vehicles.

However, Lainé expects pressure suit use by the space jet's passengers and pilot for the "first year of operation" while vehicle integrity is proven. EADS has spacesuit design experience, its Friedrichshafen site developed the suit for the European Hermes spaceplane.

The Astrium business plan is for one flight a week. This is because at the beginning Lainé's team wants to take the rocket engine out and inspect it. Whether a new engine is installed after each flight depends on how easy it is to inspect and then re-install the flown rocket motor.

Lainé also wants to tap scientific and military markets. Science missions could be used for microgravity experiments or to conduct Earth observation. Through the vehicle's windows cameras could map a large area quickly or a telescope could look outward or downward.

His plan does not exclude VIP sales of the vehicle, but despite the business jet-like design of the space jet, Lainé confirmed that he has not spoken to any other aircraft manufacturers, such as Dassault.

Until now the project has been secret, although the European Union and the European Space Agency both have space-tourism projects that Astrium could have participated in.

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