JSC2011-E-040193 (2 March 2011) --- NASA astronaut Chris Ferguson (left), STS-135 commander, confers with astronaut Rex Walheim, mission specialist, as the Atlantis crew participates in a briefing before a training session in the Vertical Motion Simulator (VMS) at NASA's Ames Research Center in Mountain View, Calif. March 2, 2011. Photo credit: NASA Photo/Houston Chronicle, Smiley N. Pool