NASA astronaut Rex Walheim undergoes a fit check of his Sokol space suit at the Zvezda facility in Moscow.

NASA astronaut Rex Walheim undergoes a fit check of his Sokol space suit at the Zvezda facility on Monday, March 28, 2011, in Moscow. The crew of the final shuttle mission traveled to Moscow for a suit fit check of their Russian Soyuz suits that will be required in the event of an emergency. ( NASA Photo / Houston Chronicle, Smiley N. Pool )