The Stratolaunch aircraft is a mobile launch platform that will enable airline-style access to space that is convenient, affordable and routine. The reinforced center wing can support multiple launch vehicles, weighing up to a total of 500,000 pounds.

Neat. So the idea is to fly this thing into the upper atmosphere and then use it as a platform to launch rockets into space? I assume the advantage is that the Stratolaunch can fly like a conventional airplane, using aerodynamics to gain altitude before the air thins out, whereas a rocket has to rely on jet propulsion for its entire journey. Being able to use both could save a lot of jet fuel.