VSS Enterprise (tail number: N339SS) was the first SpaceShipTwo (SS2) spaceplane, built by Scaled Composites for Virgin Galactic. As of 2004, it was planned to be the first of five commercial suborbital SS2 spacecraft planned by Virgin Galactic. It was also the first ship of the Scaled Composites Model 339 SpaceShipTwo class, based on upscaling the design of record-breaking SpaceShipOne. The VSS Enterprise'''s name was an acknowledgement of the USS Enterprise from the Star Trek television series. The spaceplane also shared its name with NASA's prototype Space Shuttle orbiter, as well as the aircraft carrier USS Enterprise. It was rolled out on 7 December 2009. SpaceShipTwo made its first powered flight in April 2013. Richard Branson said it "couldn't have gone more smoothly". Enterprise was destroyed during a powered test flight on 31 October 2014, killing one pilot, Michael Alsbury, and seriously injuring another, Peter Siebold. This was the first spacecraft-related accident in which part, but not all, of the crew survived. An investigation revealed the accident was caused by premature deployment of the "feathering" system, the ship's descent device; the NTSB also faulted the spacecraft's design for lacking fail-safe mechanisms that could have deterred or prevented early deployment. Flight test program Initial projections by Virgin Galactic in 2008 called for test flights to begin in late 2009 and commercial service to start in 2011. This schedule was not achieved, with captive carry and glide flight tests beginning in 2010, and the first test flight under rocket power in 2013. In October 2009, Virgin Galactic CEO Will Whitehorn outlined the flight test program for SpaceShipTwo. The test program includes seven phases: Vehicle ground testing Captive carry under White Knight Two Unpowered glide testing Subsonic testing with only a brief firing of the rocket Supersonic atmospheric testing Full flight into suborbital space Execute a detailed and lengthy appraisal process with the FAA/AST to demonstrate the system's robustness and eventually obtain a commercial launch license to begin commercial operations. On 22 March 2010, the SpaceShipTwo vehicle VSS Enterprise underwent a captive carry test flight, with the parent White Knight Two aircraft, VMS Eve, performing a short flight while carrying the Enterprise. A second test flight was made on 16 May 2010, reaching SS2's launch altitude (51,000 feet) and lasting nearly five hours, in order to facilitate "cold soak" testing of SS2's avionics and pressurization system. Thereafter, "a simulated spaceship descent/glide mission was