ISS024-E-011996 (16 Aug. 2010) --- NASA astronaut Tracy Caldwell Dyson, Expedition 24 flight engineer, attired in her Extravehicular Mobility Unit (EMU) spacesuit, is pictured in the Quest airlock of the International Space Station as the final of three planned spacewalks to remove and replace an ammonia pump module that failed July 31 draws to a close.