By Irene Mona Klotz
in Mojave, California
The team behind Monday's historic first private space flight is trying to work out what went wrong with the flight control system on SpaceShipOne.
Melvill was taken off his intended course
The craft experienced a serious anomaly between the time its motor ignited and when the vehicle reached the pinnacle of the voyage 100km above the Earth.
Pilot Mike Melvill had to use a back-up system to control SpaceShipOne.
The Scaled Composites team says there will be no attempt on a $10m space prize until it understands the fault.
Aircraft developer Burt Rutan made a blunt assessment of the problem, which could have ended pilot Melvill's life and wrecked the $25m effort to demonstrate a passenger-carrying reusable suborbital spaceship.
"The anomaly we had today is the most serious flight safety systems problem that we have had in the entire programme," said Rutan, during a press conference following the flight.
"The fact that our back-up system worked and we made a beautiful landing makes me feel very good."
The problem during the flight concerns Scaled Composites...
Rutan said the team was assessing a sudden roll seconds after SpaceShipOne's motor ignited and a more serious glitch that occurred when Melvill reached the highest peak of his suborbital flight.
He was attempting to tweak his altitude by manoeuvring the nose of the plane when the flight control system that operates flaps on the ship's wings failed.
Melvill activated the back-up system but the ship was already off course by 35km (22 miles).
The problem also ate into the engine performance during the climb to space and kept Melvill short of reaching his intended mark 110km (68 miles) above the atmosphere.
SpaceShipOne reached an altitude of 100.12km (328,491ft) - high enough to earn not only his astronaut wings but also a mention in the Guinness Book of Records.
...but the back-up worked and the vehicle came down safely
Rutan said the ship's next flight was to have been the first of two runs required to win the $10m Ansari X-Prize contest.
The non-profit X-Prize Foundation of St Louis, Missouri, will award the cash and a very large trophy to the first team that sends a three-person craft to the altitude reached by SpaceShipOne on Monday, and then repeats the flight in the same vehicle within two weeks.
Unlike Monday's flight, the X-Prize run will have to have additional people aboard, or ballast equivalent to two passengers.
SpaceShipOne, however, is grounded until the team figures out why the flight control system failed.
"There is no way we would fly again without knowing the cause and without assuring we have totally fixed it because it's a very critical system," Rutan said.