Behind the Scenes with the Atlantis Crew

Photographer Smiley N. Pool documents the four astronauts who will ride the last space shuttle as they get ready for their historic mission
Smiley N. Pool / Houston Chronicle / AP

Weightless Training
Astronaut Rex Walheim is aided by divers in the Neutral Buoyancy Laboratory near the Johnson Space Center as he works in a mock up of the space shuttle's payload bay, part of a training exercise for a space walk, March 10, 2011.

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