STS-335 (135) crew members Rex Walheim and Sandy Magnus

JSC2010-E-181483 (27 Oct. 2010) --- Attired in a training version of his Extravehicular Mobility Unit (EMU) spacesuit, NASA astronaut Rex Walheim, STS-135 mission specialist, participates in a spacewalk training session in the waters of the Neutral Buoyancy Laboratory (NBL) near NASA's Johnson Space Center. Divers are in the water to assist Walheim in his rehearsal, which is intended to help prepare him for work on the exterior of the International Space Station. STS-135 is planned to be the final mission of the space shuttle program. Photo credit: NASA or National Aeronautics and Space Administration