In 1998 SpaceDev acquired all of the intellectual property, designs, and test results generated by over 200 hybrid rocket motor firings by the American Rocket Company over its eight year life. SpaceShipOne, the first private manned spacecraft, was powered by SpaceDev's hybrid rocket motor burning HTPB with nitrous oxide. However nitrous oxide was the prime substance responsible for the explosion that killed three in the development of the successor of SpaceShipOne at scaled composites in 2007.
SpaceDev was developing the SpaceDev Streaker, an expendable small launch vehicle, and SpaceDev Dream Chaser, capable of both suborbital and orbital human space flight. Both Streaker and Dream Chaser use hybrid rocket motors that burn nitrous oxide and the synthetic rubber HTPB. SpaceDev was acquired by Sierra Nevada Corporation in 2009, becoming its Space Systems division, which continues to develop Dream Chaser for NASA's Commercial Crew Development contract.
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