|Posted by [email protected] on January 12, 2012 at 12:15 AM|
Air-launched spacecraft have been out of favour for decades, but the concept was a serious contender when NASA sought proposals for the Space Shuttle in the 1960s.
Now they're being revisited by an all-star cast of private spaceflight glitterati: Paul Allen, co-founder of Microsoft and backer of SpaceShip One; Burt Rutan, founder of Scaled Composites and builder of both SpaceShipOne and Virgin Galactic's SpaceShipTwo; Elon Musk, founder of SpaceX, which is soon to fly its own rocket to the International Space Station.
They've founded Stratolaunch Systems with the aim of creating a working air-launched spacecraft capable of carrying payloads into orbit within five years, and with the reliability and regularity of commercial air freight.
An air-launched spacecraft doesn't have to carry the propellant to reach all the way into space, and its carrier aircraft can be completely reusable, flying back to pick up another spacecraft when it's payload has departed.
It can also fly to launch locations suitable for reaching a variety of orbits and inclinations, both equatorial and polar, rather than being restricted to the orbits allowed by a fixed launch site.
Stratolaunch's carrier aircraft will be the largest aircraft ever flown, weiging more than 500,000kg and with a wingspan of more than 115m. It will have six 747-style engines and fly from large runways like that at Kennedy Space Center, Florida.
Fortunately, the Space Shuttle left a legacy of large runways around the world for emergency landings, and Strayolaunch will be able to fly 2,400 km from its base to its launch point.
SpaceX will build a multi-stage booster to reach low Earth orbit, and the goal is to provide manned launches once the system has proven reliable for unmanned cargo.