SpaceShipTwo was carried aloft by its mothership to an altitude of 45,000 feet and released over the Mojave Desert. After the separation, SpaceShipTwo, manned by two pilots, flew freely for 11 minutes before landing at an airport runway followed by the mothership.
The entire test flight lasted about 25 minutes.
"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. Sunday was the first time the spaceship flew on its own.
The news was hailed by space tourism advocates.
The "flight marks another key milestone towards opening the space frontier for private individuals, researchers, and explorers," John Gedmark, executive director of the Commercial Spaceflight Federation, said in a statement.
Whitesides said SpaceShipTwo will make a series of additional glide flights before rocketing to 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. Some 370 customers have plunked down deposits totaling $50 million, according to Virgin Galactic.
Commercial flights will fly out of New Mexico where a spaceport is under construction. Officials from Virgin Galactic and other dignitaries will gather at the spaceport Oct. 22 for an event commemorating the finished runway. The event will also feature a flyover by SpaceShipTwo and WhiteKnightTwo.
Online: Virgin Galactic