British entrepreneur Sir Richard Branson has unveiled Virgin Galactic's new vessel, designed to take passengers on a sub-orbital flight as part of the world's first commercial space tourism service.

SpaceShipTwo (SS2), which will be called the Virgin Space Ship (VSS) Enterprise, has taken five years to develop and will undergo an extensive test-flight programme after being revealed at a ceremony held at Mojave Air and Spaceport, US.

The spaceship can accommodate up to six passengers and two pilot astronauts and is around twice the size of the SpaceShipOne vessel, which was designed and built by Burt Rutan and Scaled Composites and flew to space three times in 2004.

SS2 test flights are scheduled to get underway in early 2010 and will take between 18-24 months to complete, although Virgin Galactic said the testing process could take longer depending on safety.

Virgin Galactic will operate commercial space flights from Spaceport America, New Mexico, which will see SS2 carried to an altitude of above 50,000ft (15.24km) by its mothership WhiteKnightTwo (WK2), before it is 'dropped' and propelled into space using its rocket motor.

Branson said: "The unveil of SS2 takes the Virgin Galactic vision to the next level and continues to provide tangible evidence that this ambitious project is not only moving rapidly, but also making tremendous progress towards our goal of safe commercial operation."

Flights will cost US$200,000 per person (£122,650, €135,508), with more than 300 paying customers already signed up for when the service launches.

Image: Mark Greenberg/Virgin Galactic