Chris Woodyard, Michael Winter and Charisse Jones

USA TODAY

MOJAVE, Calif. -- Federal aviation crash investigators were expected here Saturday to open the probe into the cause of the crash of Virgin Galactic's tourism spaceship, which claimed the life of one pilot and badly injured the other.

Also due at the airport Saturday is Virgin Group President Richard Branson, the British billionaire and adventurer who had become the public face of the space venture. He tweeted a reassuring message to his staff and said he was on his way.

The accident Friday came during a test flight over the Mojave Desert, about 25 miles north of the Mojave Air and Spaceport where Virgin and its partner, Scaled Composites, base their operations.

A photographer told the Associated Press that SpaceShipTwo blew up shortly after its engine fired when it was dropped from the WhiteKnightTwo aircraft that carried it aloft to 45,000 feet, the Associated Press reported. Wreckage was scattered across desert railroad tracks near Cantil, in Kern County.

But two other witnesses said there was no explosion. Marlena Rowley of Mojave told USA TODAY she was watching the test next to her husband and all looked normal. She says she saw two pieces, which is normal when the spaceship separates from the mothership. But her husband, watching through binoculars, turned to her and said, "that doesn't look good." She says she wasn't aware there was an accident until she heard the sirens of emergency vehicles.

Also, Stuart Witt, the airport's director, said he didn't see anything unusual during the test.

"I will tell you from my eyes and my ears that I detected nothing that appeared abnormal," he told reporters. "If there was a huge explosion, it didn't occur. I didn't see it,"



The pilot ejected and was taken to a hospital, but the co-pilot suffered fatal injuries, the Kern County Sheriff's Office reported. Their identities were not immediately released.

Virgin Galactic said the craft "suffered a serious anomaly resulting in the loss of the vehicle." The malfunction, which occurred about two minutes after ship was released, was not immediately identified.

The test was the fourth powered flight for the rocket-glider but the first using a new fuel. SpaceShipTwo had last flown under its own power in January.

The test, conducted by Scaled Composites, Virgin Galactic's partner, began about 9:20 a.m. PT when the mothership took off with the spacecraft. The weather was clear, and winds were light at time of the accident, according to AccuWeather meteorologists. The spacecraft separated form the mothership at 10:10 a.m. and the first signs of trouble came two minutes later.

"Space is hard, and today is a tough day," Virgin Galactic CEO George Whitesides told reporters. "We are going to be supporting the investigation to figure out what happened today and we're going to get through it."

Friday's flight was the 55th time SpaceShipTwo had been released by the mothership and was flying independently.

Branson has been developing the suborbital craft at the Mojave spaceport, northeast of Los Angeles. The company had hoped to begin commercial flights next year.

Development of the spacecraft's rocket motor has been costly, and deadly.

In July 2007, three facility workers died and three were injured in an explosion during a test of the vehicle's propellant system by Scaled Composites, which was founded by aviation entrepreneur Burt Rutan.

Virgin Galactic announced in May that it was changing SpaceShipTwo's hybrid propellant because the original rubber-based fuel mix caused serious engine instability after firing for about 20 seconds.

Friday marked the first test flight using a new, plastic-based fuel.

Branson told USA TODAY in 2011 that he envisioned Virgin Galactic expanding from suborbital to orbital travel and even flights between continents that could be done in a fraction of the time they take by airplane.

Made of carbon composites, SpaceShipTwo was about twice a large as its prototype predecessor, SpaceShipOne. It was 60 feet long with a cabin diameter of 90 inches, about the size of a Falcon 900 executive jet without a floor. In addition to two pilots, it was designed to carry six passengers.

"The spaceship can be thought of as an air launched glider with a rocket motor and a couple of extra systems for spaceflight," the company says.

In 2011, development costs for SpaceShipTwo were estimated at $400 million, three times the original projections.

Virgin Galactic is owned by Branson's Virgin Group and Aabar Investments PJS of Abu Dhabi, United Arab Emirates. Seats for future flights cost $250,000, prepaid.

SpaceShipTwo is one of several spacecraft owned by New York-based Virgin Galactic, a unit of privately held Virgin Group. The company also owns the mothership WhiteKnightTwo – which Branson christened Eve, after his mother – and LauncherOne, an orbital launch vehicle.

The loss of SpaceShipTwo comes on the heels of the explosion late Tuesday of an unmanned commercial resupply rocket seconds after liftoff at NASA's facility on the Eastern Shore of Virginia.

Woodyard reported from Mojave, Winter from Washington and Jones from New York