A mechanism designed to slow the descent of Virgin Galactic鈥檚 SpaceShipTwo was deployed earlier than intended prior to the spacecraft鈥檚 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.
鈥淲e are a long way from finding cause, we still have months and months of investigation to do,鈥� said Christopher Hart of the US National Transportation Safety Board (NTSB) at a press briefing this morning .
Immediately after the crash some experts pointed to the vehicle鈥檚 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.
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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. 鈥淲e had an unusual amount of data regarding this accident because it was a test flight,鈥� 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鈥檚 descent 鈥� a stabilising process called feathering that works similarly to the fall of a badminton shuttlecock.
SpaceShipTwo鈥檚 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鈥檚 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鈥檚 training and safety procedures, the vehicle鈥檚 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鈥檚 findings will determine Virgin Galactic鈥檚 future plans 鈥� its partner, Scaled Composites, is part way through construction of a second SpaceShipTwo, and will probably have to modify the design following the crash. 鈥淚f the cause was human error, this is a very different issue than a mechanical failing of the spacecraft,鈥� says Sadlier, and could mean a shorter delay in resuming flights.
鈥淭he early days of commercial aviation were also marked with tragedy, but overcame the challenges to become the global industry it is today,鈥� he says. 鈥淭he space tourism industry must show similar determination, dedication and resolve to rise to the challenge.鈥�
