SpaceShipTwo was carried to 45,000 feet over the Mojave Desert and released. It flew freely for 11 minutes before landing at an airport runway, according to company officials. It was the first time the spaceship flew on its own.
"It flew beautifully," said Virgin Galactic chief executive George Whitesides.
The six-passenger SpaceShipTwo is undergoing rigorous testing before it can carry tourists to space. In the latest test, SpaceShipTwo did not fire its rocket engine to climb to space.
Until now, SpaceShipTwo has flown attached to the wing of its special jet-powered mothership dubbed WhiteKnightTwo.
"It's a very big deal," Virgin president Sir Richard Branson said, "There are a number of big deals on the way to getting commercial space travel becoming a reality. This was a very big step. We now know that the spaceship glides. We know it can be dropped safely from the mothership and we know it can land safely. That's three big ticks."
"The next big step will be the rocket tests actually on the spacecraft itself," Branson said. "We've obviously have done thousands of rocket tests on the ground, the next big test is in the air. We'll be doing gentle rocket tests in the air, ultimately culminating into taking the spaceship into space."
SpaceShipTwo, built by famed aircraft designer Burt Rutan, is based on a prototype that won a $10 million prize in 2004 for being the first manned private rocket to reach space.
Tickets to ride aboard SpaceShipTwo cost $200,000.
About 370 people have already signed up for the thrill.
Virgin Galactic hopes to start flights for tourists within 18 months.