Virgin Galactic SpaceShip2 Test Flight

MOJAVE, CA - APRIL 29: (EXCLUSIVE COVERAGE) (EDITORIAL USE ONLY, NO SUBJECT SPECIFIC TV BROADCAST DOCUMENTARIES OR BOOK USE) WK2 and SS2 pilots during an early morning briefing, lead by senior pilot, Dave Mckay prior to the first powered flight of Virgin Galactic's SpaceShipTwo on April 29, 2013 in Mojave, California. SpaceShipTwo is a private enterprise aircraft, designed to carry paying passengers into space. The spacecraft was dropped from the mothership at high altitude and fired it's engine for a approximate 16-second burn taking the craft through the sound barrier. The hybrid rocket motor is fueled by nitrous oxide and a rubber propellent combination. The motor can be "shut down" at any time for safety and flight requirement purposes. (Photo by Jason DiVenere/Virgin Galactic/Getty Images)