JSC2010-E-181484 (27 Oct. 2010) --- Attired in a training version of her Extravehicular Mobility Unit (EMU) spacesuit, NASA astronaut Sandy Magnus, 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 Magnus in her rehearsal, which is intended to help prepare her 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