Virgin Galactic's SpaceShipTwo rocket plane was set loose for its first gliding flight today, about 45,000 feet above California's Mojave Desert — and landed to a chorus of cheers minutes later. That's one small step for gliders, but one giant leap for SpaceShipTwo and the future of suborbital space tourism.

The free-flying test was chronicled as it happened by Popular Mechanics' Joe Bargmann from the Mojave Air and Space Port, where the spaceship's builder, Scaled Composites, has its headquarters. Scaled has been working on the craft for years as a commercial follow-up to the history-making, prize-winning spaceflights of SpaceShipOne in 2004. The $100 million-plus development effort is being bankrolled by Virgin's billionaire founder, Richard Branson, who was among the crowd watching today's flight.

More than 300 would-be passengers have already put down more than $45 million in deposits for $200,000-a-seat rides on the plane. The experience will include a roller-coaster rocket ride to a spaceworthy altitude of more than 65 miles, several minutes of weightlessness, a picture-window view of the curving Earth beneath the black sky of space ... and spaceflight bragging rights for years afterward.

Eventually, the price is expected to work its way down to mere tens of thousands of dollars, particularly as competitors such as Armadillo Aerospace, Blue Origin and XCOR Aerospace join the market.

Today's test flight began with SpaceShipTwo hooked to its White Knight Two mothership for takeoff. Once the two linked-up planes reached 45,000 feet, the crews prepared to unhook the smaller craft for its glide. "We are armed," the cockpit crew radioed, according to Popular Mechanics' account. "Four, three, two, one, release release release!"

SpaceShipTwo glided through the air for 11 minutes and landed back at the Mojave airstrip, with White Knight Two touching down soon afterward. In a Twitter update, Virgin Galactic reported that SpaceShipTwo, also known as the VSS Enterprise, completed "her first solo glide flight successfully."

The glide test, piloted by Scaled Composites engineer Pete Siebold with Mike Alsbury as co-pilot, marked another milestone for SpaceShipTwo's test program. It came less than a year after the plane was rolled out for its first public viewing, and less than seven months after its first "captive-carry" flight.

"This was one of the most exciting days in the whole history of Virgin," Branson said in a statement released after the test. "For the first time since we seriously began the project in 2004, I watched the world's first manned commercial spaceship landing on the runway at Mojave Air and Space Port, and it was a great moment. Now, the sky is no longer the limit and we will begin the process of pushing beyond to the final frontier of space itself over the next year."

The Mojave Air and Space Port's general manager, Stuart Witt, hailed today's test in a statement released by the Commercial Spaceflight Federation: "First flight days are always extraordinary," Witt said. "This team effort by so many has been punctuated by a successful first test flight, and now everyone seeking a ride to space is a giant step closer."

More glides will follow in the months ahead to fine-tune the plane's aerodynamics. SpaceShipTwo's first powered tests, which will involve actually lighting up the plane's hybrid rocket engine, are expected to begin next year. The rocket ship's designer, Burt Rutan, has said he'd like to fly 50 to 100 tests before SpaceShipTwo begins commercial service — which would likely mean the first paying passengers could step aboard in 2012 or 2013.

The National Geographic Channel is scheduled to air a documentary about the making of SpaceShipTwo on Oct. 18. Here's a press preview:

More about commercial spaceflight:

• Slideshow: The making of SpaceShipTwo
• Boeing aims for orbital space tours by 2015
• Private space stations edge closer to reality

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Space Adventures, the Virginia-based company that has worked with the Russians to send seven millionaires to the International Space Station, says it has reached "a unique agreement" with the Boeing Co. on space transportation services — and executives from both companies will be talking about the deal next week.

Today's announcement, sent to me via e-mail, merely notes that a noontime news briefing will be conducted next Wednesday at Boeing's offices in Arlington, Va. Speakers will include Brewster Shaw, vice president and general manager of Boeing's space exploration division (and a former astronaut); as well as Eric Anderson, co-founder and chairman of Space Adventures.

Space Adventures isn't saying anything further about the substance of the deal — but you could easily make the case that each company has something the other one wants:

• Under the terms of an $18 million agreement with NASA, Boeing is designing a spaceship known as the CST-100 that can carry up to seven people to the space station and other destinations in low Earth orbit. But the aerospace giant has said that ferrying astronauts for NASA isn't a lucrative enough business by itself. It also needs commitments for private-sector clients. That's one reason why Boeing already has partnered with Nevada-based Bigelow Aerospace, which is planning to put a commercial space station into orbit as early as 2014 or 2015. I'm guessing that Boeing would love to have an even bigger market for its commercial space transport services.

• For years, Space Adventures has been building up a list of clients willing to take multimillion-dollar trips into orbit — including, for example, Sergey Brin, one of Google's billionaire co-founders. In the past, the company has purchased open seats aboard the Russian Soyuz spacecraft that have brought astronauts to the space station and back. However, now that the station's long-duration capacity has been expanded from three to six, those open seats have dried up. Particularly with the imminent retirement of NASA's shuttle fleet, Soyuz seats are needed to ferry the professional astronauts back and forth. The outlook for tourist seats could improve a couple of years from now, but I'm guessing that Space Adventures would love to have a deal with Boeing like the one they've had with the Russians.

But these are just my guesses. Feel free to speculate about what all this could mean for the two companies, and for space commercialization in general, by leaving your comments below. And tune in on Wednesday to get the full story.

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