JSC2010-E-170910 (1 Oct. 2010) --- NASA astronauts Chris Ferguson (right), STS-135 commander; and Rex Walheim, mission specialist, participate in a training session on the middeck of the crew compartment trainer (CCT-2) in the Space Vehicle Mock-up Facility at NASA's Johnson Space Center. United Space Alliance crew trainer Robert (Rob) Tomaro (background) assisted the crew members. STS-135 is planned to be the final mission of the space shuttle program. Photo credit: NASA or National Aeronautics and Space Administration