CAPE CANAVERAL, Fla. -- STS-134 Pilot Greg H. Johnson prepares to perform touch-and-go landings aboard a Shuttle Training Aircraft (STA) on the Shuttle Landing Facility runway at NASA's Kennedy Space Center in Florida. An STA is a Gulfstream II jet that is modified to mimic the shuttle's handling during the final phase of landing. Kelly and Johnson will practice landings as part of standard training before space shuttle Endeavour's launch to the International Space Station. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- STS-134 Commander Mark Kelly and Pilot Greg H. Johnson perform touch-and-go landings aboard a Shuttle Training Aircraft (STA) on the Shuttle Landing Facility runway at NASA's Kennedy Space Center in Florida. An STA is a Gulfstream II jet that is modified to mimic the shuttle's handling during the final phase of landing. Kelly and Johnson will practice landings as part of standard training before space shuttle Endeavour's launch to the International Space Station. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- STS-134 Commander Mark Kelly has completed touch-and-go landings and disembarks from a Shuttle Training Aircraft (STA) on the Shuttle Landing Facility runway at NASA's Kennedy Space Center in Florida. An STA is a Gulfstream II jet that is modified to mimic the shuttle's handling during the final phase of landing. Kelly and Johnson will practice landings as part of standard training before space shuttle Endeavour's launch to the International Space Station. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- STS-134 Pilot Greg H. Johnson prepares to perform touch-and-go landings aboard a Shuttle Training Aircraft (STA) on the Shuttle Landing Facility runway at NASA's Kennedy Space Center in Florida. An STA is a Gulfstream II jet that is modified to mimic the shuttle's handling during the final phase of landing. Kelly and Johnson will practice landings as part of standard training before space shuttle Endeavour's launch to the International Space Station. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- STS-134 Commander Mark Kelly and Pilot Greg H. Johnson perform touch-and-go landings aboard a Shuttle Training Aircraft (STA) on the Shuttle Landing Facility runway at NASA's Kennedy Space Center in Florida. An STA is a Gulfstream II jet that is modified to mimic the shuttle's handling during the final phase of landing. Kelly and Johnson will practice landings as part of standard training before space shuttle Endeavour's launch to the International Space Station. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- STS-134 Commander Mark Kelly has completed touch-and-go landings in a Shuttle Training Aircraft (STA) on the Shuttle Landing Facility runway at NASA's Kennedy Space Center in Florida. An STA is a Gulfstream II jet that is modified to mimic the shuttle's handling during the final phase of landing. Kelly and Johnson will practice landings as part of standard training before space shuttle Endeavour's launch to the International Space Station. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- STS-134 Commander Mark Kelly prepares to perform touch-and-go landings aboard a Shuttle Training Aircraft (STA) on the Shuttle Landing Facility runway at NASA's Kennedy Space Center in Florida. An STA is a Gulfstream II jet that is modified to mimic the shuttle's handling during the final phase of landing. Kelly and Johnson will practice landings as part of standard training before space shuttle Endeavour's launch to the International Space Station. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- STS-134 Pilot Greg H. Johnson prepares to perform touch-and-go landings aboard a Shuttle Training Aircraft (STA) on the Shuttle Landing Facility runway at NASA's Kennedy Space Center in Florida. An STA is a Gulfstream II jet that is modified to mimic the shuttle's handling during the final phase of landing. Kelly and Johnson will practice landings as part of standard training before space shuttle Endeavour's launch to the International Space Station. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- STS-134 Pilot Greg H. Johnson prepares to perform touch-and-go landings aboard a Shuttle Training Aircraft (STA) on the Shuttle Landing Facility runway at NASA's Kennedy Space Center in Florida. An STA is a Gulfstream II jet that is modified to mimic the shuttle's handling during the final phase of landing. Kelly and Johnson will practice landings as part of standard training before space shuttle Endeavour's launch to the International Space Station. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- STS-134 Commander Mark Kelly and Pilot Greg H. Johnson return after performing touch-and-go landings aboard a Shuttle Training Aircraft (STA) on the Shuttle Landing Facility runway at NASA's Kennedy Space Center in Florida. An STA is a Gulfstream II jet that is modified to mimic the shuttle's handling during the final phase of landing. Kelly and Johnson will practice landings as part of standard training before space shuttle Endeavour's launch to the International Space Station. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- STS-134 Pilot Greg H. Johnson has completed touch-and-go landings and disembarks from a Shuttle Training Aircraft (STA) on the Shuttle Landing Facility runway at NASA's Kennedy Space Center in Florida. An STA is a Gulfstream II jet that is modified to mimic the shuttle's handling during the final phase of landing. Kelly and Johnson will practice landings as part of standard training before space shuttle Endeavour's launch to the International Space Station. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. -- STS-134 Commander Mark Kelly and Pilot Greg H. Johnson are ready to take off and perform touch-and-go landings aboard a Shuttle Training Aircraft (STA) on the Shuttle Landing Facility runway at NASA's Kennedy Space Center in Florida. An STA is a Gulfstream II jet that is modified to mimic the shuttle's handling during the final phase of landing. Kelly and Johnson will practice landings as part of standard training before space shuttle Endeavour's launch to the International Space Station. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett