Space shuttle Endeavour

Space Shuttle Discovery leaves the Vehicle Assembly Building (VAB) on its way to the Orbiter Processing Facility at Kennedy Space Center August 11, 2011 in Cape Canaveral, Florida. Space Shuttles Endeavour and Discovery switched buildings as they are being decommissioned with the end of the Shuttle program. (Photo by Roberto Gonzalez/Getty Images)

Space Shuttle Discovery leaves the Vehicle Assembly Building (VAB) on its way to the Orbiter Processing Facility at Kennedy Space Center August 11, 2011 in Cape Canaveral, Florida. Space Shuttles Endeavour and Discovery switched buildings as they are being decommissioned with the end of the Shuttle program. (Photo by Roberto Gonzalez/Getty Images)