A rocket plane will attempt to become the first privately funded spacecraft to leave the Earth’s atmosphere later this month. The spacecraft, called SpaceShipOne, is also the leading candidate in an upcoming $10 million international space race to send passengers into space on privately funded spacecraft.

The SpaceShipOne program is led by aircraft designer and aviation expert Burt Rutan. Rutan and his company, Scaled Composites, of Mojave, Calif., are funded solely by billionaire Paul Allen, cofounder of Microsoft Corp.

During a test flight last May, SpaceShipOne achieved an altitude of 40 miles, a record for highest altitude achieved by a non-governmental spacecraft. Rutan and his team expect to reach 62 miles into space on the next flight on June 21.

SpaceShipOne will be carried 50,000 feet above the earth by a special carrier jet dubbed White Knight. After the rocket plane is release, it will fire its rocket motor for about 80 seconds and climb vertically at Mach 3. That speed will bring it to about 62 miles above the Earth. Although that altitude is not enough to go into orbit, the pilot will experience weightlessness for about 3 minutes and see the blackness of space.

The SpaceShipOne team will compete with 26 other teams in the $10 million Ansari X Prize. The winning craft has to carry three people into sub-orbital space twice within a two-week period. Some have compared the Ansari X Prize to the Orteig Prize that spurred Charles Lindbergh to fly solo non-stop from New York to Paris in 1927.