SpaceShipOne, piloted by 62-year-old South African-born Michael Melvill, reached an altitude of more than 62 miles (100 kilometers) putting it halfway towards winning the prize aimed at spawning commercial space travel.

Citing radar readings, the competition's judges announced the craft reached 337,500 feet (101,250 meters), surpassing the 328,000 feet (98,400 meters) considered the edge of space.

But even as the world's first nongovernmental space vessel took man a step closer to a new era of galactic tourism, it rolled dramatically dozens of times.

An ebullient Melvill and team officials conceded that the terrifying "vertical roll" was unplanned, but played down the potential of danger and pointed to his quick recovery of control of the rocket plane that was travelling up to 3,500 kilometers an hour.

Dressed in a black jumpsuit and standing triumphantly atop the stubby rocket plane after a smooth-as-glass landing at this former US military air base in the California desert, Melvill declared it a "near-perfect flight."

"Now that was fun," he said. "I really feel like I nailed it," he said adding that he even paused to take photos of the earth from the cockpit as he became weightless for around 3.5 minutes after the corkscrew rolls.

"I wasn't worried about it," Melvill said. "In fact, it was pretty cool. Probably I stamped on something too quickly and caused the roll.

"A victory roll at the top is important to a pilot," he quipped, adding that he could have attained 360,000 feet if had not shut off the rocket engine 11 seconds early after the ship began its dizzying rolls.

SpaceShipOne designer and commercial space flight pioneer Burt Rutan said that while the rolls were spectacular, they did not damage the craft that -- unlike the Space Shuttle -- was designed to take the strain and was 100 times safer than other manned spacecraft.

"That would have been an accident if that had happened on the Space Shuttle on in an X-15 (plane)," he said. "We'd be looking for small pieces."

"My heart kind went into my throat," said Microsoft founder Paul Allen, who joined with Rutan's company Scaled Composites to form the Mojave Aerospace Ventures team behind SpaceShipOne.

But Ansari X Prize judges said Melvill and his rocketship had successfully soared through stage one of the competition.

To win the privately-funded 10-million-dollar purse, a manned, reusable spacecraft must be sent into space twice in two weeks. SpaceShipOne's second flight to clinch the purse is tentatively scheduled for Monday.

Rutan said technicians would seek out the cause of the rolls, which he said could have been caused by wind buffeting, before going ahead with Monday's flight.

A specially adapted jet called White Knight, which carried SpaceShipOne on its belly, took off from an air base in California's Mojave Desert at 7:11 am (1411 GMT).

SpaceShipOne, which made history when it entered space for the first timeJune 21 with Melvill at the controls, separated from the jet about an hour later at around 47,000 feet (15 kilometers) and ignited its rocket engine to reach space.

It then glided to a landing at the dusty air base littered with the hulks of retired passenger planes at 8:34 am (1534 GMT), to the cheers and applause of thousands of relieved onlookers.

The X Prize was launched eight years ago to ignite private space travel in the same way the Orteig prize did to inspire Charles Lindbergh's first transatlantic flight in 1927.

The winning vessel must carry the pilot and the equivalent weight of two passengers. That ballast was made up of a variety of items including the ashes of Rutan's late mother, a teddy bear and personal items belonging to team members.

There are 26 vehicles in contention for the Ansari prize, but SpaceShipOne is the most advanced.

Rutan said SpaceShipOne had already changed space travel forever and that in a few years people would be able to buy tickets for sub-orbital flights.

On Monday Rutan and British tycoon Richard Branson announced a 14-million-pound (25-million-dollar) tie-up between Virgin Atlantic Airways and Mojave Aerospace Ventures to set up Virgin Galactic, the first company to offer the public trips into space using SpaceShipOne's technology.

"If you look at this (project) in terms of opening up a new era commercial human space flight, you have already done that," George Nield of the US Federal Aviation Administration's space wing told the SpaceShipOne team.

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