Along with SS2's mothership, the VMS Eve (or "WhiteKnightTwo"), the spaceship is intended to kick start the commercial space tourism industry, and will offer daily flights from the company's Spaceport America in New Mexico.
"This is truly a momentous day," Branson said in prepared remarks. "The team has created not only a world first but also a work of art."
Construction of the spacecraft began in 2007. It draws on the knowledge from the development of the SpaceShipOne and its successful flights in 2004, which won the Ansari X-Prize for completing the world's first manned private space flights.
The SpaceShipTwo will be an entirely new vehicle capable of carrying up to six passenger astronauts and up to two pilot astronauts into space on a sub-orbital flight.
Both the SS2 and its mothership use carbon composite materials for fuel efficiency. The WhiteKnightTwo mothership is powered by four Pratt and Whitney PW308A engines, some of the mostefficient commercial jet engines available, and the SS2 spaceship will be powered by a hybrid rocket motor currently under development.
The twin fuselage and central payload area configuration allow for easy access to WK2 and to the spaceship for passengers and crew; the design also aids operational efficiencies and turnaround times. The mothership has now also completed a year of rigorous and successful first phase flight testing prior to today's attachment of SS2.
An extensive test flying program of the SS2 is expected to begin "shortly."
The WhiteKnightTwo mothership is expected to carry the SS2 spacecraft to above 50,000 feet, or 16 kilometers, before it drops the SS2, which will then use a rocket motor to launch into space from that altitude.
Governor Arnold Schwarzenegger of California and Governor Bill Richardson of New Mexico are expected to christen SS2 with the name "Virgin Space Ship Enterprise."
Virgin Galactic says that 12,500 jobs have been created by new space companies, and the Virgin Galactic project alone has about 600 people working on activities related to the project. The company expects that number to rise to 1,100 jobs during the peak of the construction phase at the space port and through the introduction of the commercial space vehicles into regular astronaut service.
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Andrew Nusca does not hold investments in the companies he covers.
Andrew Nusca is the editor of SmartPlanet.