LOS ANGELES (AP) — Virgin Galactic's experimental spaceship broke apart in flight over California's Mojave Desert after a device to slow the craft's descent prematurely deployed, federal investigators said Sunday.
National Transportation Safety Board Acting Chairman Christopher Hart said that while no cause for Friday's crash of SpaceShipTwo has been determined, investigators found the "feathering" system — which rotates the tail to create drag — was activated before the craft reached the appropriate speed.
The system requires a two-step process to deploy. The co-pilot unlocked the system but Hart said the second step occurred "without being commanded."
"What we know is that after it was unlocked, the feathers moved into the deploy position and two seconds later we saw disintegration," Hart said.
The investigation is months from being completed and pilot error, mechanical failure, the design and whether there was pressure to continue testing are among many things being looked at, Hart said.
"We are not edging toward anything, we're not ruling anything out," Hart said. "We are looking at all these issues to determine the root cause of this accident."
The co-pilot Michael Alsbury, 39, was killed. Peter Siebold, 43, who piloted the mission, parachuted to the ground and is receiving treatments at a hospital for serious injuries.
Virgin Galactic — owned by billion Richard Branson's Virgin Group and Aabar Investments PJS of Abu Dhabi — plans to fly passengers to altitudes more than 62 miles above Earth. The company sells seats on each prospective journey for $250,000.
Branson had hoped to begin flights next year but said Saturday that the project won't resume until the cause of the accident is determined and the problems fixed.
Hart said a review of footage from a camera mounted to the ceiling of the cockpit shows the co-pilot moving the feathering lever to the unlock position.
The feathering is a feature unique to the craft to help it slow as it re-enters the atmosphere. After being unlocked, a lever must be pulled to rotate the tail section toward a nearly vertical position to act as a rudder. After decelerating, the pilots reconfigure the tail section to its normal position so the craft can glide to Earth.
Hart said the feathers activated at Mach 1.0, the speed of sound or 760 mph. They shouldn't have deployed until the craft had at least reached a speed of Mach 1.4, or more than 1,000 mph.
SpaceShipTwo tore apart Friday about 11 seconds after it detached from the underside of its jet-powered mother ship and fired its rocket engine for the test flight. Initial speculation was that an explosion occurred but Hart said the fuel and oxidizer tanks and rocket engine were found and showed no sign of being burned or breached.
Virgin Galactic CEO George Whitesides issued a statement Sunday to tamp down conjecture about the cause of the crash.
"Now is not the time for speculation," he said. "Now is the time to focus on all those affected by this tragic accident and to work with the experts at the NTSB, to get to the bottom of what happened on that tragic day, and to learn from it so that we can move forward safely with this important mission."
SpaceShipTwo has been under development for years and, like all space projects, has suffered setbacks. In 2007, an explosion killed three people on the ground and critically injured three others during a ground test in the development of a rocket engine.
Prior to Hart's announcement, Geoff Daly, an engineer who worked on the space shuttle, renewed criticism of Virgin Galactic's use of nitrous oxide to power the ship.
The nitrous oxide is used with fuel to provide propulsion. Engineers had recently changed the fuel system, switching from a rubber-based fuel to one that used plastics. The new fuel had been tested on the ground but not in flight until Friday.
Daly was co-author of a critical report on the 2007 incident at Scaled Composites, the Northrop Grumman-owned designer of SpaceShipTwo. The report was critical of Virgin's claims that nitrous oxide was safe to use in engines for passenger flight, and it complained that the public was never given a full accounting of what happened.
In a June 2013 letter, Daly asked the FAA to put a hold on an experimental flight permit for SpaceShipTwo to ensure the safety of personnel on the ground and in the spacecraft.
The FAA said it would look into his complaint, according to memos posted online, but Daly said no flights of SpaceShipTwo were halted.
A report by the California Division of Occupational Safety and Health said the 2007 blast occurred three seconds after the start of a cold-flow test of nitrous oxide. The engine was not firing during the test at the Mojave Air and Space Port.
The loss of SpaceShipTwo was the second fiery setback for commercial space travel in less than a week. On Tuesday, an unmanned commercial supply rocket bound for the International Space Station exploded moments after liftoff in Virginia.