NASA astronaut Chris Ferguson looks out over the Facility SVMF s Johnson Space Center in Houston.

NASA astronaut Chris Ferguson, STS-135 commander, left, looks out over the Space Vehicle Mock-up Facility (SVMF) after the crew of the final shuttle mission trained in the facility at NASA?s Johnson Space Center in Houston on June 29, 2011. The training marked the crew's final scheduled session in the SVMF. NASA astronaut Sandy Magnus, mission specialist, is in background at center. Photo credit: NASA photo/Houston Chronicle, Smiley N. Pool