The Astrium space division of Europe’s biggest aerospace company, EADS,

disclosed June 13 the basic design of a space plane it proposes to build to carry wealthy tourists to 100 kilometers in altitude for several minutes of weightlessness.

The result of two years of unpublicized work by a small team of Astrium engineers, the plane features two conventional jet engines and a central rocket engine powered by liquid methane and liquid oxygen. In its general shape and size, it resembles a business jet with two exceptionally long wings – and windows whose number and location are designed for passengers floating freely in the cabin.

officials said they would give themselves until the end of this year to round up financial partners in the project, which they said would require about 1 billion euros ($1.34

billion) to complete the plane’s design and development and build the first models. The plane could begin flying in 2012 if investment partners are found this year, Astrium President Francois Auque said.

, whose background is in finance, said Astrium has concluded that space tourism of this sort, if handled correctly, could attract up to 15,000 paying passengers per year by 2020. Astrium says its planes, each flying once per week and carrying four passengers per flight, could capture 30 percent of this global market.

At 200,000 euros per ticket, that would be a business generating gross revenues of 900 million euros per year for the Astrium project if the

numbers prove accurate.

is prime contractor for Ariane 5 rockets and for Europe’s contribution to the international space station. EADS builds Airbus commercial jets and military aircraft. Auque said that across the company’s divisions there resides almost all the know-how necessary to build the rocket plane.

Taking off from an as yet-undetermined spaceport using its two conventional jet engines, the plane would climb to 12 kilometers in altitude before its rocket engine ignites, powering the vehicle through the atmosphere before beginning a coast phase to a

100-kilometer apogee, providing

passengers with about three minutes of near-zero-gravity experience.

The round trip is expected to last

about 90 minutes.

said one side benefit of the project is that it would

shatter the cliche that established aerospace giants like EADS have lost their imagination and sense of daring. “Conventional wisdom says only small companies can innovate,” he told reporters. “We are demonstrating that even a European leader can be innovative.”

Chief Technical Officer Robert Laine, who leads the Astrium team working on the space plane concept,

declined to say how much of its own resources the company would be willing to invest alongside its co-investors. “We will make our business plan available to co-investors only,” Laine said.

said the project envisions building five initial vehicles, with the planes capable of being refurbished quickly enough to fly once per week. The liquid-methane/liquid-oxygen rocket engine would need to be replaced after 30 flights.

would not be the service operator; that role would be contracted to one or more outside companies. Laine said technology-transfer restrictions would prohibit the use of much non-European technology in the plane’s design.

He said Astrium has surveyed other space-tourism start-up projects, mainly in the United States

, and found most of them lacking in engineering or business-model seriousness. “There are those who think you can design a rocket plane in a garage,” Laine said. “Suffice it to say that that is not our niche.”

Auque said Astrium and its parent company, EADS, have enough experience in designing Airbus aircraft and rockets to be confident in their ability to design a craft that meets the stringent safety and operating-cost constraints of such as business. “The big part for us will be finding private finance partners. If we succeed, we will open the door to private financing of space.”

U.S. spaceplane designer, Burt Rutan, the founder of Scaled Composites LLC, manufacturer of SpaceshipOne, the first privately built vehicle to fly into space, expressed skepticism about the potential entry of EADS into the suborbital space tourism market.

and his Scaled Composites team are busy working on SpaceShipTwo, which like SpaceShipOne will be a two-vehicle system using a huge carrier/release plane, called White Knight 2 as its first stage.

“Like other spaceship concepts that take off from a runway [XCOR and Rocketplane are examples] or those that do rocket-powered vertical launches, the EADS vehicle will weigh more than twice as much (per passenger) as SpaceShipTwo and require more than twice the rocket impulse,” Rutan said.

“This relates to significant increases in operational costs,” he added, also noting that failure modes on ascent tend to be more risky at low altitudes.

“The non-recurring development cost of a suborbital spaceship that has rocket and jet engines – both of which leave the atmosphere and experience re-entry – will be far more than our SpaceShipTwo program,” he said.

Scaled Composites now has more than 250 employees, about twice the number of employees the firm had just three years ago. the company is building SpaceShipTwo and White Knight 2 for Virgin Galactic, Sir Richard Branson’s suborbital space travel business.

Special correspondent Leonard David contributed to this article from Golden, Colo.