Virgin Galactic's SpaceShipTwo during a sub-orbital flight

An artist's conception of Virgin Galactic's SpaceShipTwo during a sub-orbital flight into space is pictured in this undated publicity photograph from Virgin Galactic.

Scaled Composites and Virgin Galactic are set to unveil SpaceShipTwo on December 7, 2009 at the Mojave Spaceport in Mojave, California. The six-passenger vehicle will undergo test flights in 2010 and start commercial flights between 2011 and 2012.