Scaled Composites, one of the competitors for the X-prize, has carried out a test flight of its SpaceShipOne vehicle mated underneath its White Knight airplane.
By Dr David Whitehouse
BBC News Online science editor
SpaceShipOne is a reusable suborbital spacecraft developed in secret with an estimated $20 million (£12.4 million) of finance, by Burt Rutan and unveiled at a recent ceremony in the Mojave Desert, California.
SpaceShipOne is slung below the White Knight aircraft
The aim of SpaceShipOne, which is carried aloft by the White Knight aircraft for the first part of its journey, is to win the $10 million X-prize which will be awarded to the first craft that can carry three people to an altitude of 100 km twice in a two-week period.
According to a report on the X Prize web site, SpaceShipOne flew attached to the underside of the fuselage of the White Knight aircraft during a test flight over the Mojave Desert on 19 May.
During the flight SpaceShipOne remained attached to White Knight. Details of the altitude and duration of the mission have not been revealed.
At the rollout of SpaceShipOne on 18 April Burt Rutan said that mated flights would begin in the near future and there would be regular reports.
SpaceShipOne will start its mission with a climb to 50,000ft under the twin-engined White Knight. SpaceShipOne will then fire its hybrid rocket engine, fuelled by a mixture of nitrous oxide and rubber, to reach the blackness of space.
After experiencing weightlessness at the top of its trajectory, the ship will extend its wings and tail and glide back to the runway that it left 90 minutes earlier.
Peter Diamandis, the X-prize foundation chairman, says that the Rutan project "has not only the potential to win the prize, but to jump-start an entire industry. This could create more astronauts in one year than have been created in the last 40 years."
Scaled Composites will not give a date for the first flight, but insiders say it is aiming for the centenary of the world's first powered flight, by the Wright Brothers, next December.