Burt Rutan an aerospace engineer, and Paul Allen, Microsoft's co-founder, hope that "SpaceShipOne," will fly 100 kilometers (62 miles) up to see where the immense blackness of space meets the blue line of the atmosphere.

In doing so they hope to take the first steps to breaking a government monopoly on space travel and introducing 10 dollars trips into space for the masses.

The pilot of the rocket will only be named Sunday. The journey will begin at about 6:30am (1330 GMT) at Edwards Air Force Base in California, in the middle of the Mojave Desert.

A jet mothership known as "The White Knight" will be launched and initially carry the rocket underneath its belly for an hour, soaring up to 15,450 metres (48,000 feet).

White Knight will then release SpaceShipOne, which weighs less than three tonnes.

The hybrid liquid and combustible solid-powered engine will then fire for about 80 seconds taking the rocket up to about 160,000 feet (50 kilometers) at a speed of more than 3,500 kilometers (2,200 miles) an hour.

SpaceShipOne will then glide up to about 340,000 feet (103km), when it lose the momentum from the engine and start to fall back to Earth.

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

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 10:30am and 11:30am (1730-1830 GMT).

The design of this particular prototype, decorated with painted blue stars, will make re-entry easier, because the aircraft will be able to fold its wings, reducing resistance and allowing the air to propel it back down like a badminton shuttle, said Rutan, whose company Scaled Composites designed the spaceship.

The characteristics of this suborbital flight reduce the risks at takeoff and reentry back into earth, as illustrated in both the 1986 Challenger and 2003 Columbia castrophes.

Rutan, in 1986, engineered the US Voyager, the first aircraft to travel around the world without refueling.

For this ambitious challenge, Rutan charmed the Allen, who was smitten with space, astronomy and science fiction, and has spent about 20 million dollars on the project.

Scaled Composites is one of 20 teams, convinced that there is a future in space tourism, and who are vying to win a 10 million dollar competition to be the first to privately finance and carry three people 100 kilometers into the sky, safely return and then do it again within two weeks.

But profit, is not one of the immediate objectives of Rutan and Allen.

They say their main aim is to end the government's monopoly on space exploration and put it in the reach of all those who can pay the price.

Plans so far are to charge 100,000 dollars a flight in the first years of business and then eventually lower the fare to 10 dollars with the arrival of other spaceships planned for 2010.

"Since Yuri Gagarin and Al Shepard's epic flights in 1961, all space missions have been flown only under large, expensive government efforts," Rutan said.

"By contrast, our program involves a few, dedicated individuals who are focused entirely on making spaceflight affordable."

Rutan said that without an entrepreneurial approach "space access would continue to be out of reach for ordinary citizens. The SpaceShipOne flights will change all that and encourage others to usher in a new, low-cost era in space travel."

SPACE.WIRE