The craft, which aims to rise more than 100 kilometers (60 miles) above the earth's surface traveling at more than three times the speed of sound, was dreamed up by Burt Rutan, 61, a US engineer who had already worked on "Voyager," which in 1986 became the first plane to fly around the world without stopping or refueling.

Since then Rutan has been working in secrecy in his hangars in Mojave, southern California, on the edge of a commercial airport.

Rutan, who heads a company named Scaled Composites LLC, announced his new challenge in 2001, with financing from billionaire Paul Allen, along with Bill Gates, co-founder of software giant Microsoft.

Scaled Composites' vice president, 62-year-old Mike Melvill, will take the helm of SpaceShipOne for its historic flight into space, organizers said Sunday.

Melvill, an American and native of South Africa, flew the rocket to an altitude of 211,400 feet in a test flight May 13, breaking the record for a privately-built craft.

The space craft weighs about three tonnes and is made of a graphite composite material. It was built and tested for some 20 million dollars.

Rutan designed the craft with broad wings and vertical stabilizers for re-entering the Earth's atmosphere.

"The wings are folded to provide a shuttlecock or feather effect to give the ship extremely high drag for reentry," said Rutan, comparing the entry to that of a badminton birdie.

"This 'care-free' configuration allows a 'hands-off' reentry and greatly reduces aero/thermal loads," he said.

The craft operates on a hybrid motor that uses both solid and liquid rocket engines. Directly behind the cockpit, which can carry a pilot and two passengers, lies the nitrous oxide liquid fuel tank, followed by the body of the rocket engine filled with the solid fuel.

SpaceShipOne is scheduled to leave the ground attached to the "White Knight," a custom-designed transport aircraft, on Monday around 6:30 am.

After one hour of flying, at an altitude of 15 kilometers (48,000 feet), the "Knight" will release SpaceShipOne, which will ignite its rocket engine and begin a vertical rise.

The rocket will burn for approximately 80 seconds, propelling the craft straight up at a speed of about 3,500 kilometers (2,200 miles) per hour, or about three and a half times the speed of sound, to a height of some 50 kilometers (160,000 feet) above the planet.

Once the rocket's fuel has been spent, the craft will continue upward for some three minutes to reach 104 kilometers (340,000 feet), a height at which it will lose speed like a spent bullet.

During this time, the pilot will feel weightless as do astronauts in space. The zero-gravity effect, lasting three minutes, will continue until SpaceShipOne returns to about 60 kilometers (200,000 feet).

The pilot will gradually take control again and from 80,000 feetkilometers) altitude, the craft will glide for about 17 minutes back to a landing at Edwards Air Base at between 10:30 am and 11:30 am (1730-1830 GMT).

SPACE.WIRE