Acting Chairman of the National Transportation Safety Board (NTSB), Christopher A. Hart, gestures during a news conference at the Mojave Air and Space Port in California, November 1, 2014. [Photo/Agencies]

Branson determined to find cause of Virgin spaceship crash, pilots identified

Can private space survive two explosions in four days?

MOJAVE, Calif. - A human-factors expert will join the investigation of the fatal crash of Virgin Galactic's passenger spacecraft to study why the co-pilot prematurely unlocked a pivoting tail section of the ship during a test flight, the National Transportation Safety Board chairman said on Monday.

The untimely engagement of the tail mechanism, designed to slow the vehicle's descent into the atmosphere from space, and the possibility that pilot error was to blame, were disclosed by the NTSB late on Sunday and have emerged as a main thrust of the inquiry into Friday's accident.

The suborbital rocket vehicle dubbed SpaceShipTwo broke into pieces over California's Mojave Desert and crashed shortly after its separation from the special jet aircraft that carries it aloft for its high-altitude launches.

The accident, which unfolded without SpacesShipTwo catching fire or exploding in flames, came on its fourth powered test flight, the first since January.

Video footage from the cockpit shows co-pilot Michael Alsbury, 39, who died in the crash, releasing a lever to unlock the twin-tail section too soon after the space plane was jettisoned from the mother ship over Southern California.

This was followed two seconds later by the premature movement of the tail, which pivots upward from the rear of the wings at a 90-degree angle and increases aerodynamic drag on the spacecraft.

Still, NTSB Chairman Christopher Hart said that investigators have yet to determine whether releasing the tail mechanism too early caused or contributed to the crash of the space plane near the Mojave Air and Space Port, about 95 miles (152 km) north of Los Angeles.

"We know already from having the lever move from lock to unlock that we need to get a human-factors person in here because the question then is why did that happen when it happened," Hart said. "The human-factors person will be here today."

MYSTERY OF PILOT'S SURVIVAL

Investigators also are trying to determine how surviving pilot Pete Siebold, 43, managed to get out of the rocket plane and parachute to the ground from a height of roughly 50,000 feet, an altitude virtually devoid of oxygen.

Hart said Siebold, now hospitalized with a shoulder injury, did not exit through the cockpit's escape hatch. "We know it wasn't through there, so how did this pilot get out?" he said.

SpaceShipTwo, developed by the fledgling space tourism company of billionaire entrepreneur Richard Branson, was designed to carry wealthy passengers on short rides into space, with Virgin Galactic planning to begin offering its first flights to paying customers next spring.

The crash came three days after the unmanned rocket of another private space company, Orbital Sciences Corp, exploded during liftoff from a commercial launch pad in Virginia on a mission to deliver cargo to the International Space Station under contract with NASA.