The VSS Unity was built to replace Virgin Galactic's original SpaceShipTwo suborbital spaceplane, which disintegrated shortly after launch in 2014. Only one of the two pilots survived the fatal crash, which investigators believe was caused by the premature unlocking of the spacecraft's feather re-entry system. It took Virgin years to build Unity and to get it ready for testing, but now that it has gone through two rocket-powered flights in supersonic speeds, Branson is feeling very optimistic. He believes his first flight aboard Unity is "months away, not years away" and has already started astronaut training.