In space shuttle Discovery's payload bay get a close look at the orbital docking system.

In space shuttle Discovery's payload bay, STS-120 crew members get a close look at the orbital docking system. Seen here are Mission Specialists Scott Parazynski (left) and Daniel Tani. After the mission, Tani will remain aboard the International Space Station and return with the STS-122 crew, targeted to launch Dec. 6. 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