Atlantis the STS-125 crew members practice an emergency escape from the shuttle.

After taking part in a simulated launch countdown aboard space shuttle Atlantis, the STS-125 crew members practice an emergency escape from the shuttle. Here they are ready to release the slidewire basket that will speed them away from Kennedy Space Center’s Launch Pad 39A. The countdown is the culmination of terminal countdown demonstration test, or TCDT, activities as preparation before launch. TCDT provides astronauts and ground crews with an opportunity to participate in various launch activities, including equipment familiarization, emergency training and the countdown. Atlantis’ STS-125 mission to service NASA’s Hubble Space Telescope is targeted for launch Oct. 14. Photo credit: NASA/Kim Shiflett