US aviation investigators think they know how Virgin Galactic's SpaceshipTwo broke up in mid-flight, but don't yet know why. The crash tragically killed co-pilot Michael Alsbury, seriously injured pilot Pete Siebold and set back CEO Richard Branson's space tourism program severely. NTSB acting chairman Christopher Hart said that the tail section on SpaceshipTwo (normally only raised during descent below Mach 1.4) deployed shortly after the rockets fired -- even though neither pilot commanded it to. As a result, the ship broke up seconds later from the excessive drag and crashed into the Mojave desert.
Normally, a two-step procedure is required to enable tail deployment: first it has to be unlocked, then a lever is moved by pilots to "feather" it into position.The NTSB said that for some unknown reason, Alsbury unlocked the tail at Mach 1, rather than at Mach 1.4 as is normal procedure during the rocket-powered ascent. Nevertheless, neither pilot touched the feathering lever (as confirmed by video in the cockpit), so the tail shouldn't have moved anyway.
Investigators said that the new information is just statement of fact and not cause. It will still take months to figure out exactly why the tail deployed on its own, and why the pilots may have unlocked it early in the first place. Early speculation on the crash focused on the use of a plastic-based rocket fuel that had never been flight-tested, but that now appears to be unrelated to the crash.
Update: In the NTSB's second press conference of the day (embedded below), acting chairman Christopher Hart said it was mistaken to say it was the copilot who moved the feathering lever from lock to unlock. According to the video, it was the person in the right seat, but they are still determining who was in which seat. He also said parts of the vehicle have been located as far as 35 miles away from the primary wreckage field, telemetry does not show that the extension of the tail was commanded by either pilot, and that the NTSB has not yet interviewed Pete Siebold.