Virgin Galactic's SpaceShipTwo, the ambitious space tourism company founded by tycoon Richard Branson, fired its rocket engine for the first time on a test flight.
In Monday's test, SpaceShipTwo took off suspended below its WhiteKnightTwo mothership. When it reached an altitude of 45,000 feet (14 kilometers) over California's Mojave Desert, the spacecraft undocked, moved a safe distance away from WhiteKnightTwo, and fired its rocket engine for 16 seconds.
Despite the short duration of the firing, the craft accelerated to Mach 1.2. It then slowed down and returned to the airport in free flight.
In subsequent tests, the engine, which burns a mixture of solid rubber and liquid nitrous oxide, will be activated for increasingly longer periods of time, until the aircraft reaches the final altitude of 100 kilometers - the official limit of space.
Future Virgin Galactic passengers will thus be able to enjoy a suborbital flight and experience weightlessness for a few minutes.
The flight is called suborbital because SpaceShipTwo cannot develop high enough speed to enter orbit.
According to the company's original schedule, tourist flights should have already begun. But testing of SpaceShipTwo and WhiteKnightTwo has been delayed, and the company is reluctant to specify when it will begin offering its services.
However, more than 500 prospective customers, including the famous British physicist Stephen Hawking, have already made deposits for their future tickets.
Virgin Galactic's spaceship will take off from the new Spaceport America space center in New Mexico.
