SPACESHIP READY FOR HISTORIC FLIGHT.

Byline: Staff and Wire Services

MOJAVE - SpaceShipOne is one flight away from clinching the Ansari X Prize, a $10 million award for the first privately developed manned rocket to reach space twice within 14 days.

SpaceShipOne was scheduled to be launched a few minutes after sunrise today in an attempt to reach an altitude of at least 328,000 feet, more than 62 miles, for the second time in less than one week.

The choice of the pilot for the flight remained a secret on the eve of launch, as it did before the flight last week.

That flight and a test flight into space on June 21 were flown by Michael Melvill, who has been awarded the nation's first commercial astronaut wings by the Federal Aviation Administration.

Melvill is one of four pilots who have undergone special training to fly SpaceShipOne.

He had difficulty controlling the ship during the June flight and by his own description was ``all over the sky,'' but still reached 62 miles.

Last week, he flew a perfect trajectory to an altitude of 337,600 feet, or nearly 64 miles, but the ship began rolling as it neared space. He said he didn't believe he made a mistake at the time, but suspected that data would later show he had caused the roll with an inadvertent rudder movement.

After the craft landed, SpaceShipOne designer Burt Rutan said he believed the roll was not serious but planned a safety analysis before a decision to proceed with the second X Prize flight.

The go-ahead decision was announced to X Prize organizers Thursday evening.

Over the weekend, Rutan posted preliminary information about the roll in a statement on his Web site, saying he will explain the complex reason at a later date but wanted to address ``incorrect rumors'' about the rolls that have appeared in news stories and Web discussions.

The first roll occurred at a high speed, about Mach 2.7, but aerodynamic loads on the spacecraft were low and decreasing rapidly, ``so the ship never saw any significant structural stresses,'' he said.

There were so many rolls because they started as the craft was nearing the edge of the atmosphere, and Melvill could not damp the motions with the aerodynamic controls, according to Rutan.

Since aerodynamic controls don't work in space, SpaceShipOne is equipped with what the Rutan team calls a reaction-control system or RCS, which uses jets of compressed gas to control movements.

Melvill successfully used the system to stop the roll before he reached the peak altitude, Rutan said.

``While we did not plan the rolls, we did get valuable engineering data on how well our RCS system works in space,'' he said.

Rutan's statement also said it was not true that the pilot defied a request to shut down the motor and let it run a few more seconds in order to reach the 100-kilometer altitude.

``While a Mission Control aerodynamist did discuss a possible abort a few seconds earlier, Mike immediately shut down the motor on the first advisory call over the radio. Mike himself was monitoring the apogee predictor during the initial rolls and was in the process of going for the thrust termination switch as he heard the advisory call,'' Rutan said.

The Ansari X Prize was first offered in 1996 by a St. Louis-based foundation to kick-start private-sector development of rocket ships that would make spaceflight available to the public.

Prize founder Peter Diamandis hoped the multimillion-dollar incentive would have the same effect on space travel that the $25,000 Orteig Prize - won by Charles Lindbergh for his solo trans-Atlantic flight from New York to Paris in 1927 - had on commercial aviation.

Major funding came from the Ansari family of Dallas, which made its wealth in the telecommunications industry. More than two-dozen teams around the world got started on projects in an effort to win the X Prize, but the SpaceShipOne team was the first to the starting line.

Funded by Microsoft co-founder Paul Allen, SpaceShipOne was developed in secret at Rutan's Mojave Airport-based Scaled Composites LLC until it was unveiled in April 2003.

Allen has not said exactly how much he has put into the project, characterizing the sum only as more than $20 million.

IF YOU GO

Mojave Airport is set to open its gates at 3 a.m. today to spectators for Burt Rutan's SpaceShipOne launch. Admission is $20 per vehicle. Traffic might be heavy.

SpaceShipOne is expected to take off attached to its mother ship at 7 a.m. It is expected to reach the altitude to ignite its rocket engine at 8 a.m. and to land at 8:30 a.m.

To reach Mojave Airport, spectators can travel north on the Antelope Valley Freeway until it becomes two-lane Highway 14 just outside Mojave. Turn right at the first stoplight onto Highway 58, then left on Airport Boulevard.

CAPTION(S):

photo, box

Photo:

(color -- ran in AV edition only) Michael Melvill, who has been awarded the nation's first commercial astronaut wings by the Federal Aviation Administration, gives a thumbs up after his successful first of two flights for a $10 million prize.

Box:

IF YOU GO (see text)