NASA's 747 Shuttle Carrier Aircraft mounted on top soars after takeoff from Edwards Air Force Base Sept. 20, 2009.

NASA’s modified 747 Shuttle Carrier Aircraft with the shuttle Discovery securely mounted on top soars into the morning sky after takeoff from Edwards Air Force Base Sept. 20, 2009. The piggyback pair was due to arrive back at NASA’s Kennedy Space Center in Florida the following day after the 2,500-mile cross-country ferry flight. Discovery had landed at Edwards Sept. 11 after the STS-128 mission to the International Space Station. The shuttle delivered more than 7 tons of supplies, science racks and equipment, as well as additional environmental hardware to sustain six crew members on the International Space Station. NASA photo /Tony Landis