Part of SpaceShipTwo in the Mojave desert (Image: Xinhua News Agency/REX)

A mechanism designed to slow the descent of Virgin Galactic’s SpaceShipTwo was deployed earlier than intended prior to the spacecraft’s crash on Friday say US officials. They are still working to determine the cause of the accident, which killed one pilot and severely injured the other.

“We are a long way from finding cause, we still have months and months of investigation to do,” said Christopher Hart of the US National Transportation Safety Board (NTSB) at a press briefing this morning laying out initial findings about the accident.

Immediately after the crash some experts pointed to the vehicle’s hybrid rocket motor, which was undergoing its first test after it was upgraded to burn a different mix of fuel. It was thought this may have caused an explosion mid-flight, but this morning Hart said the motor and its fuel tanks were found intact amongst the debris scattered across the Mojave desert in California. SpaceShipTwo pilot Peter Siebold is alert and talking to doctors treating his injuries, but his co-pilot Michael Alsbury died in the crash.


The NTSB has been examining vehicle telemetry and video transmitted by SpaceShipTwo before the crash and have found another potential issue: the early deployment of the feathering mechanism. “We had an unusual amount of data regarding this accident because it was a test flight,” said Hart.

Early feathering

SpaceShipTwo is designed to deploy from its WhiteKnightTwo mother ship, then fire its rocket to reach the 100 kilometre altitude generally recognised as the edge of outer space. On its return to Earth, the wings are meant to rotate up to a 65 degree angle to provide drag and slow the craft’s descent – a stabilising process called feathering that works similarly to the fall of a badminton shuttlecock.

SpaceShipTwo’s feathering is controlled by two levers, one that unlocks the wings and another that moves them to the feathering position. The pilots are meant to shift these levers once the craft’s rocket burn has finished and it reaches a speed of Mach 1.4, but Hart said the video from the cockpit showed that one pilot unlocked the wings at Mach 1 and they then deployed to the feathering position by themselves.

Hart stressed that the NTSB has not determined that this was the cause of the crash and they will continue to investigate Virgin Galactic’s training and safety procedures, the vehicle’s design, and other factors such as whether there was pressure to continue testing.

Greg Sadlier, space analyst at consultancy firm London Economics, says the NTSB’s findings will determine Virgin Galactic’s future plans – its partner, Scaled Composites, is part way through construction of a second SpaceShipTwo, and will probably have to modify the design following the crash. “If the cause was human error, this is a very different issue than a mechanical failing of the spacecraft,” says Sadlier, and could mean a shorter delay in resuming flights.

“The early days of commercial aviation were also marked with tragedy, but overcame the challenges to become the global industry it is today,” he says. “The space tourism industry must show similar determination, dedication and resolve to rise to the challenge.”