Mission Specialist Mike Fossum leads two astronauts part of the launch dress rehearsal known as the terminal countdown demonstration test.

On Launch Pad 39A at NASA's Kennedy Space Center, STS-124 Mission Specialist Mike Fossum leads two other astronauts to the slidewire basket area after completing the simulated launch countdown, part of the launch dress rehearsal known as the terminal countdown demonstration test. The crew is practicing emergency egress from the 195-foot level of the fixed service structure. TCDT provides astronauts and ground crews with an opportunity to participate in various simulated countdown activities, including a simulated launch countdown, equipment familiarization and emergency egress training. On the STS-124 mission, the crew will deliver and install the Japanese Experiment Module – Pressurized Module and Japanese Remote Manipulator System. Discovery's launch is targeted for May 31. Photo credit: NASA/Kim Shiflett