Virgin Galactic's adventure into space tourism moves closer to operational flight status. Just last week the second stage of its two-stage suborbital vehicle, SpaceShipTwo, reached its highest altitude so far in a rocket-powered test flight over the Mojave test site.

This vehicle was designed and built by Scaled Composites as its Model 339 air-launched spaceplane. It has been specifically designed for commercial space tourism with a top speed of 2,485 mph. the vehicle has a length of 60 feet, with a wingspan of 27 feet. Although its first flight was on October 10, 2010, it is still in the flight-testing phase. Scaled Composites is under contract to The Spaceship Company, which is wholly owned by Virgin Galactic.

When operational, SpaceShipTwo will be carried to its launch altitude by a jet-powered first-stage vehicle, White Knight Two, another Scaled Composites creation. Once released from White Knight Two, the second-stage vehicle will fly into the upper atmosphere, powered by a specially-built rocket motor.

Upon completion of each flight, SpaceShipTwo glides back to Earth and performs a conventional runway landing. On 29 April 2013, the suborbital vehicle successfully performed its first powered test flight. It is now in the advanced stages of flight testing, prior to becoming operational later this year. Virgin Galactic plans to operate a fleet of five SpaceShipTwo vehicles, each providing private passenger services.

The company has been accepting bookings for some time. Each ticket for a suborbital flight carries a price tag of $200,000. This spaceplane is also being considered for use as a scientific payload carrier for NASA and others.

In its latest test flight, SpaceShipTwo climbed to an altitude of more than 13 miles and reached a top speed of Mach 1.4. This was its third successful supersonic powered flight, bringing it one step closer to that first operational flight from Spaceport America in Las Cruces, N.M.