The STS-135 crew members enjoy a light moment during a simulated launch countdown.

In the Operations and Checkout Building at NASA's Kennedy Space Center in Florida, the STS-135 crew members enjoy a light moment during a simulated launch countdown. From left are Jerry Ross, chief of the Vehicle Integration Test Office and former NASA astronaut, Commander Chris Ferguson, Mission Specialists Sandy Magnus and Rex Walheim, and Pilot Doug Hurley.

As part of the Terminal Countdown Demonstration Test (TCDT), the crew members are taken to Kennedy's Launch Pad 39A and strapped into space shuttle Atlantis to practice the steps that will be taken on launch day. Atlantis and its crew are targeted to lift off July 8, taking with them the Raffaello multi-purpose logistics module packed with supplies and spare parts to the International Space Station. The STS-135 mission also will fly a system to investigate the potential for robotically refueling existing satellites and return a failed ammonia pump module to help NASA better understand the failure mechanism and improve pump designs for future systems. STS-135 will be the 33rd flight of Atlantis, the 37th shuttle mission to the space station, and the 135th and final mission of NASA's Space Shuttle Program. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: NASA/Kim Shiflett