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NASA's flagship, Space Shuttle Discovery, arrives at Dulles International Airport on April 17, 2012 on the back of NASA's modified 747 SCA (Shuttle Carrier Aircraft) for her official retirement. Shuttle Discovery is being handed over to the Smithsonian's Udvar-Hazy Center National Air and Space Museum as part of the museum's permanent collection. © Mike Lynaugh

NASA's flagship, Space Shuttle Discovery, arrives at Dulles International Airport on April 17, 2012 on the back of NASA's modified 747 SCA (Shuttle Carrier Aircraft) for her official retirement. Shuttle Discovery is being handed over to the Smithsonian's Udvar-Hazy Center National Air and Space Museum as part of the museum's permanent collection.

© Mike Lynaugh