Space shuttle Atlantis' STS-135 crew members are instructed on the slidewire basket emergency exit system.

On Launch Pad 39A at NASA's Kennedy Space Center in Florida, space shuttle Atlantis' STS-135 crew members are instructed on the slidewire basket emergency exit system at the pad. From left are Mission Specialists Rex Walheim and Sandy Magnus, Pilot Doug Hurley and Commander Chris Ferguson.

The astronauts are at Kennedy to participate in a launch countdown dress rehearsal called the Terminal Countdown Demonstration Test (TCDT) and related training. 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