View of backup payload specialist Robert Thirsk during Zero-G training

S84-37532 (18 July 1984) --? Robert B. Thirsk, backup payload specialist for 41-G appears to be shaking hands with an unoccupied extravehicular mobility unit (EMU) during a familiarization flight aboard NASA?s KC-135 aircraft. Thirsk, representing Canada?s National Research Council (NRC), serves as backup to Marc Garneau on the seven-member crew for Challenger?s October 1984 flight. This aircraft is used extensively for training and exposing Shuttle crewmembers to weightlessness as well as for evaluation of equipment and experiments scheduled for future flights.