The STS-120 crew gathers after practicing egress part of the prelaunch terminal countdown demonstration test.

The STS-120 crew gathers at the slidewire basket area on Launch Pad 39A after practicing emergency egress, part of the prelaunch terminal countdown demonstration test, or TCDT. Seen here in their launch and entry suits are (from left) Pilot George Zamka, Commander Pamela Melroy and Mission Specialist Scott Parazynski. Their name patches reflect the nicknames the crew gave each other for the event. The TCDT at NASA's Kennedy Space Center provides astronauts and ground crews an opportunity to participate in various launch preparation activities, including equipment familiarization and emergency training. The STS-120 mission will deliver the U.S. Node 2 module, named Harmony, aboard space shuttle Discovery to the International Space Station. Discovery is targeted to launch on its 14-day mission at 11:38 a.m. EDT on Oct. 23. Photo credit: NASA/Kim Shiflett