Mission Specialist Paolo Nespoli has his helmet fitted on his launch and entry suit preparing for launch.

STS-120 Mission Specialist Paolo Nespoli has his helmet fitted on his launch and entry suit, preparing for launch. The fitting is part of terminal countdown demonstration test, or TCDT, activities the crew is undertaking at NASA's Kennedy Space Center. The TCDT also includes emergency egress procedures, equipment familiarization and a simulated launch countdown. Mission STS-120, which will carry the Italian-built U.S. Node 2 to the International Space Station, is targeted for launch on Oct. 23. Photo credit: NASA/Kim Shiflett