On Friday 31 October the first of two SpaceShipTwo vehicles was lost during a powered test flight over the Mojave Desert, California, killing one pilot, Michael Alsbury, and injuring a second, Pete Siebold.

The two pilots had conducted a large number of test fights in the type and had flown the maiden flight of SpaceShipTwo in 2010. Several changes to the design had been required when Virgin Galactic took direct control of the engine test programme earlier this year after effecting a change in the type of propulsion system employed, previously provided by Sierra Nevada. SpaceShipTwo had made 54 flights as of the date of the accident of which three had been powered.

The accident followed separation from the White Knight Two carrier aircraft and after ignition of the rocket motor but the cause is not yet known and may take several months to determine, according to the US National Transportation Safety Board which is the body charged with conducting an investigation.

Experimental test pilots are frequently called upon to conduct precise and meticulously planned evaluations in flight and to do so they necessarily place their lives at risk. Michael Alsbury lost his life in the pursuit of human progress and with a desire to push back the frontiers of knowledge in engineering and technology. As such he joins a distinguished group of men and women who have similarly lost their lives in the development and application of flying machines.

The events of 31 October have been preceded by numerous accidents and disasters over the last century of flight as human beings strive to push back the presumed limits of flight and flying on this planet and beyond. Other lives will be lost in the future for similar reasons. The legacy of their sacrifice must inspire others to take up the baton and press forward with determination and a resolute will.

Spaceflight magazine and the British Interplanetary Society extends heartfelt condolences to the family and close friends of Michael Alsbury and conveys its most earnest hope that Pete Siebold will complete a full recovery.

David Baker

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