spaceSpace and Physics

‘Feathering’ Descent System Deployed Early in Fatal Virgin Galactic Crash

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Lisa Winter

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110 ‘Feathering’ Descent System Deployed Early in Fatal Virgin Galactic Crash
Virgin Galactic

On the morning of October 31, Virgin Galactic’s SpaceShipTwo (SS2) spaceplane experienced an “in-flight anomaly” just two minutes after separating from the launch vehicle during a flight test. The unspecified anomaly resulted in a crash in the Mojave Desert, killing the co-pilot and severely injuring the pilot. 

The pilots were employed by Scaled Composites, a company that develops concept aircraft at Mojave Air and Space Port in California. They had over 30 years of flight experience between them. 


Co-pilot Michael Alsbury, 39, was killed in the crash and leaves behind a wife and two children. A crowdfunding campaign has been set up by Scaled to help the family, reaching nearly 75% of their goal in the first day. Alsbury piloted SS2 for the first time in 2010. 

Peter Siebold, 43, was able to eject from the aircraft and was airlifted to a local hospital, where he is being treated for his injuries. Siebold is the  Director of Flight Operations at Scaled, and the company released a statement that he is alert and able to speak with his family and doctors. 

[Images contributed by Scaled Composites]

The investigation began the next morning when representatives from the National Transportation Safety Board (NTSB) arrived at the scene and started analyzing telemetry and debris from the scene, which was scattered across two miles. The engine and fuel tanks were discovered intact, refuting early claims that one or both had been the source of the problem. While the team was using a new fuel mixture that had never before been used in the air, it had been tested on the ground several times without incident. 

Responding to claims that Virgin Galactic was too ambitious and knowingly used unsafe equipment, the company responded:

“At Virgin Galactic, we are dedicated to opening the space frontier, while keeping safety as our ‘North Star’. This has guided every decision we have made over the past decade, and any suggestion to the contrary is categorically untrue. We have the privilege to work with some of the best minds in the space industry, who have dedicated their lives to the development of technologies to enable the continued exploration of space. All of us at Virgin Galactic understand the importance of our mission and the significance of creating the first ever commercial spaceline. This is not a mission that anyone takes lightly.”

Acting NTSB chairman Christopher Hart made a public statement Saturday afternoon, indicating that the “feathering” mechanism that aids in the descent had been prematurely activated.

The SS2 was designed to bring tourists up into space, allowing them to experience weightlessness. Rather than being launched vertically with a rocket, the SS2 takes off horizontally from Mojave Space Port with help from the launch vehicle WhiteKnightTwo. 

Once the pair reach an altitude of 15 kilometers (50,000 feet), SS2 is released and drops into a free fall for a few seconds before firing its rocket engine. The SS2 then climbs 95 km (310,000 feet) more, reaching space. At the top of the arc, passengers experience several minutes of weightlessness before the descent. The “feathering” allows the spacecraft to slow down and make a controlled, unpowered glide back to the runway.

[Image via Virgin Galactic]

Because this was a test flight, there was much more data being collected than in normal accidents, which will help the investigation. Video from inside the cockpit revealed Siebold prematurely engaging the first of two steps in SS2’s feathered descent feature. However, nothing should have happened without completing the second step, which neither pilot appears to have done. 


The formal investigation will likely continue over the next several months before any official cause of the in-flight anomaly and subsequent crash is decided.


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