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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.

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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.

SpaceShipOne ushered in a new space age dominated by deep-pocketed entrepreneurs with dreams of making space voyages as mundane as airplane travel. That vision remains unfulfilled.

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.

Matthew Upchurch, 46, who reserved a future flight, said he felt goosebumps when he saw White Knight Two.

"It was very emotional for me," he said. "I thought, 'Oh my God, we're getting closer.'"

"Having invested all my faith in it, I'm so excited to see the actual thing," said artist Namira Salim, a customer who is lined up for a ride on Branson's Virgin Galactic, before the unveiling ceremony.

The mothership rollout also moved Rutan, who has made a career of designing unconventional aircraft.

"Even though this is a pretty weird airplane, we all expect it to fly very well," said Rutan, who traded his usual leather jacket for a white button-down shirt with a Virgin Galactic logo.

Meanwhile, SpaceShipTwo, which is 70 percent complete, remained under wraps.

It sat in a hangar several hundred feet away from White Knight Two shrouded in a black tarp. A sticker on it read "Coming Soon ... To a Spaceport Near You."

In the history of spaceflight, most astronauts have been in government programs. In recent years, a handful of wealthy people have paid about $20 million each to ride Russian rockets to the international space station.

Virgin Galactic envisions a future where space voyages will become as common as airplane travel. It wants to fly 500 people into space in the first year for $200,000 a head.

If it succeeds, that would be on par with the same number of people who have gone up in 45 years of space travel.

So far, more than 250 wannabe astronauts have paid the full amount or put down a deposit to fly with Virgin Galactic, but when they will float in zero gravity is unknown.

Rutan has declined to release a schedule. Virgin Galactic stopped predicting after it said in a 2004 press release that flights could begin in 2007.

Virgin Galactic renamed White Knight Two after Branson's mother, Eve. After the rollout, Branson and his mother popped open a bottle of Champagne next to the craft, which sports a decorative motif of a blond woman flying a Virgin flag.

White Knight Two has a wingspan of 140 feet, about the same as a World War II B-29 Superfortress bomber.

The mothership is designed to tuck SpaceShipTwo under the center of its wing and release it at 50,000 feet.

After separation, SpaceShipTwo will fire its hybrid rocket and climb some 62 miles above Earth, the internationally recognized boundary of space.

The spaceflight — up and back down without circling the Earth — will include about five minutes of weightlessness.

The total trip, from White Knight Two's takeoff to SpaceShipTwo's unpowered landing, will last about 2½ hours.

Virgin Galactic already has lofty plans for White Knight Two besides space tourism.

Company executives envision the aircraft can be used as a launcher of small satellites into low Earth orbit. With the proper permits, the craft can also be adapted to fight wildfires or be used as an emergency rescue vehicle.

Monday's unveiling was bittersweet for Rutan's company, Scaled Composites LLC.

A year ago, three technicians were killed in an explosion while testing SpaceShipTwo's propellant system.

Scaled, which was since bought by Northrop Grumman Corp., held a ceremony last week in honor of the fallen workers.

The company is appealing a state fine of $28,870 for workplace violations in connection with the blast.