NASA astronaut Chris Ferguson undergoes a fit check of his Sokol space suit at the Zvezda facility on Tuesday, March 29, 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 )

JSC2011-E-040291 (28 March 2011) --- NASA astronaut Doug Hurley, STS-135 pilot, dons a Sokol spacesuit March 28, 2011, at the Zvezda facility in Moscow. Hurley's name appears first in English and then in Russian on his suit. The order is reversed on the suits of Russian cosmonauts. Photo credit: NASA Photo/Houston Chronicle, Smiley N. Pool

JSC2011-E-040323 (29 March 2011) --- NASA astronaut Sandy Magnus, STS-135 mission specialist, looks at a snow-covered neighborhood out the window of a van carrying her back to Star City following a fit check of her Sokol spacesuit at the Zvezda facility in Moscow March 29, 2011. The crew of the final shuttle mission traveled to Moscow for a suit fit check of their Russian spacesuits which would be required in the event of an emergency. Photo credit: NASA Photo/Houston Chronicle, Smiley N. Pool

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 )

JSC2011-E-040322 (29 March 2011) --- NASA astronaut Sandy Magnus, STS-135 mission specialist, undergoes a fit check of her Sokol spacesuit March 29, 2011, at the Zvezda facility 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. Photo credit: NASA Photo / Houston Chronicle, Smiley N. Pool

JSC2011-E-040290 (27 March 2011) --- Moscow stretches out in all directions as seen from a commercial flight carrying NASA astronauts Doug Hurley, STS-135 pilot, and Rex Walheim, mission specialist, to Moscow, Russia on March 27, 2011. The crew of the final shuttle mission traveled to Moscow to be fitted for Russian Sokol spacesuits which would be required in the event of an emergency. If the shuttle is unable to return to Earth, the crew will remain on the International Space Station and return on a staggered basis in the course of a year on scheduled Soyuz flights to the station. Photo credit: NASA Photo/Houston Chronicle, Smiley N. Pool

JSC2011-E-040325 (30 March 2011) --- NASA astronaut Doug Hurley, STS-135 pilot, waits in a pressure chamber before a test of his Sokol spacesuit at the Zvezda facility in Moscow March 30, 2011. The crew of the final shuttle mission traveled to Moscow for a suit fit check of their Russian spacesuits which would be required in the event of an emergency. Photo credit: NASA Photo/Houston Chronicle, Smiley N. Pool

NASA astronaut Chris Ferguson undergoes a fit check of his Sokol space suit at the Zvezda facility on Tuesday, March 29, 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 )

JSC2011-E-040302 (28 March 2011) --- NASA astronaut Rex Walheim's name is seen in both English and Russian on a "Penguin" suit during a suit fit check at the Zvezda facility in Moscow on March 28, 2011. The crew of the final shuttle mission traveled to Moscow for a suit fit check of their Russian Sokol suits which would be required in the event of an emergency. Photo credit: NASA Photo/Houston Chronicle, Smiley N. Pool

JSC2011-E-040319 (29 March 2011) --- NASA astronaut Chris Ferguson, STS-135 commander, undergoes a fit check of his Sokol spacesuit at the Zvezda facility in Moscow, Russia on March 29, 2011. The crew of the final shuttle mission traveled to Moscow for a suit fit check of their Russian Sokol suits which would be required in the event of an emergency. Photo credit: NASA Photo/Houston Chronicle, Smiley N. Pool

JSC2011-E-040298 (28 March 2011) --- NASA astronaut Rex Walheim, STS-135 mission specialist, undergoes a fit check of his Sokol spacesuit at the Zvezda facility in Moscow on March 28, 2011. The crew of the final shuttle mission traveled to Moscow for a suit fit check of their Russian suits would be required in the event of an emergency. Photo credit: NASA Photo/Houston Chronicle, Smiley N. Pool

JSC2011-E-040299 (28 March 2011) --- NASA astronaut Rex Walheim, STS-135 mission specialist, undergoes a fit check of his Sokol suit at the Zvezda facility in Moscow on March 28, 2011. The crew of the final shuttle mission traveled to Moscow for a suit fit check of their Russian Sokol spacesuits which would be required in the event of an emergency. Walheim's name appears first in English and then in Russian on his suit. The order is reversed on the suits of Russian cosmonauts. Photo credit: NASA Photo/Houston Chronicle, Smiley N. Pool

JSC2011-E-040324 (30 March 2011) --- NASA astronaut Doug Hurley, STS-135 pilot, waits in a pressure chamber before a test of his Russian Sokol spacesuit at the Zvezda facility in Moscow on March 30, 2011. The crew of the final shuttle mission traveled to Moscow for a suit fit check of their Russian Sokol suits which would be required in the event of an emergency. Photo credit: NASA Photo/Houston Chronicle, Smiley N. Pool

Space suit designer Oleg Gerasimenko shares some tips on the Sokol suit with NASA astronaut Rex Walheim during a fit check 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 )

JSC2011-E-040332 (30 March 2011) --- NASA astronauts Rex Walheim and Chris Ferguson visit Red Square in Moscow on March 30, 2011. The crew of the final shuttle mission traveled to Moscow for a suit fit check of their Russian Soyuz suits which would be required in the event of an emergency. Photo credit: NASA Photo/Houston Chronicle, Smiley N. Pool

JSC2011-E-040330 (30 March 2011) --- NASA astronaut Chris Ferguson (foreground), STS-135 commander, visits Red Square in Moscow on March 30, 2011. The crew of the final shuttle mission traveled to Moscow for a suit fit check of their Russian Sokol suits which would be required in the event of an emergency. Photo credit: NASA Photo/Houston Chronicle, Smiley N. Pool