Attached to a diesel-powered tractor, space shuttle Endeavour is towed from the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida to the Orbiter Processing Facility, or OPF. After landing in California to end the STS-126 mission, Endeavour returned to Kennedy on a piggyback flight atop a shuttle carrier aircraft. In the OPF, Endeavour will begin preparations for its next mission, STS-127, targeted for May 2009. Photo credit: NASA/Jack Pfaller