JOHNSON SPACE CENTER, Houston, Texas --- STS135-S-002 --- Attired in training versions of their shuttle launch and entry suits, these four astronauts take a break from training to pose for the STS-135 crew portrait. Pictured are NASA astronauts Chris Ferguson (center right), commander; Doug Hurley (center left), pilot; Rex Walheim and Sandy Magnus, both mission specialists. Photo credit: NASA or National Aeronautics and Space Administration