MOJAVE, Calif. – The space tourism race marked a milestone Monday as British mogul Sir Richard Branson and American aerospace designer Burt Rutan waved to a crowd from inside the cabin of an exotic jet that will carry a passenger spaceship to launch altitude.

The photo-op was the public unveiling of the White Knight Two mothership before a crowd of engineers, dignitaries and space enthusiasts at the Mojave Air & Space Port in the high desert north of Los Angeles.

The four-engine jet, with its 140-foot single wing, is an engineering marvel. The space between its twin fuselages is where SpaceShipTwo, the passenger rocket being built for Branson’s Virgin Galactic, will be mounted.

White Knight Two, billed as the world’s largest all-carbon-composite airplane, is “one of the most beautiful and extraordinary aviation vehicles ever developed,” Branson proclaimed.

White Knight Two is the brainchild of Rutan, who made history in 2004 when his SpaceShipOne became the first private, manned craft to reach space. SpaceShipOne accomplished it with help from White Knight Two’s smaller predecessor, White Knight. After winning $10 million for the feat, Rutan partnered with Branson, chairman of Virgin Group, to commercialize the prototype.

White Knight Two’s long-awaited rollout, a year after a deadly explosion rocked Rutan’s test site, is the first tangible sign of progress toward making space tourism a reality. Despite the glitz surrounding the event, significant hurdles remain.

The aircraft must undergo at least a year of rigorous flight tests starting in the fall. In addition, workers have to finish building SpaceShipTwo, which will be flown by two pilots and carry six passengers.