Technicians work on the space shuttle Endeavour after it landed at Kennedy Space Center in Cape Canaveral, Florida June 1, 2011.

Astronauts of STS-134 pose for a group photograph shortly after landing onboard the space shuttle Endeavour at the Shuttle Landing Facility (SLF) at Kennedy Space Center in Cape Canaveral, Florida, June 1, 2011. From left: Flight engineer Roberto Vittori with the Italian Space Agency, pilot Greg Johnson, commander Mark Kelly and spacewalkers Mike Fincke, Greg Chamitoff, and Andrew Feustel.

Space shuttle Endeavour commander Mark Kelly leaves the crew transports after returning to earth onboard Endeavour at the Kennedy Space Center in Cape Canaveral, Florida June 1, 2011.

Space shuttle Endeavour commander Mark Kelly (Right) talks with NASA Administrator Charles Bolden after landing at the Kennedy Space Center in Cape Canaveral, Florida June 1, 2011.

Space shuttle Endeavour mission specialist Greg Chamitoff (Center) is helped around the runway by mission specialist Michael Fincke (Left) and pilot Gregory Johnson after landing at the Kennedy Space Center in Cape Canaveral, Florida June 1, 2011.

The crew of space shuttle Endeavour (Left to Right) European Space Agency astronaut Roberto Vittori, pilot Gregory Johnson, commander Mark Kelly, mission specialist Michael Fincke, mission specialist Greg Chamitoff and Andrew Feustel wave after landing at the Kennedy Space Center in Cape Canaveral, Florida June 1, 2011.

The crew of the space shuttle Endeavour (Left to Right) European Space Agency astronaut Roberto Vittori, pilot Gregory Johnson, commander commander Mark Kelly, mission specialist Michael Fincke, mission specialist Greg Chamitoff and Andrew Feustel is joined by NASA Administrator Charles Bolden (Center) after landing at the Kennedy Space Center in Cape Canaveral, Florida June 1, 2011.

Mission Commander Mark Kelly speaks at a crew press conference following landing of the space shuttle Endeavour at the Kennedy Space Center in Cape Canaveral, Florida June 1, 2011.

Mission Commander Mark Kelly speaks at a crew press conference following the landing of space shuttle Endeavour at the Kennedy Space Center in Cape Canaveral, Florida June 1, 2011.