In space shuttle Discovery's payload bay, STS-120 crew members get a close look at the equipment and payloads. Seen here is Mission Specialist Scott Parazynski. The TCDT provides astronauts and ground crews an opportunity to participate in various simulated countdown 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. Launch of Discovery on mission STS-120 is targeted for Oct. 23 at 11:38 a.m. EDT on a 14-day mission. Photo credit: NASA/Kim Shiflett