41D-3138 (4 Sept 1984)--- Canada's backup payload specialist assists the two 41-G prime payload specialists during a training session in the Johnson Space Center's Shuttle mockup and integration laboratory. Robert Thirsk (without helmet) represents the National Research Council (NRC) and is backup to Marc Garneau (nearest camera), also of the NRC. Paul D. Scully-Power, seated in the other middeck seat for the launch phase, is a civilian oceanographer with the U.S. Navy. The 41-G flight aboard the Challenger is NASA's first to utilize a crew of more than six persons. This photograph was taken by Otis Imboden.