During Terminal Countdown Demonstration Test TCDT activities at Launch Pad 39A.

During Terminal Countdown Demonstration Test (TCDT) activities at Launch Pad 39A, the Mission STS-117 crew members speak to the media during a question-and-answer session. From the left are Commander Rick Sturckow, Pilot Lee Archambault, and Mission Specialists Patrick Forrester, Steven Swanson, Danny Olivas and James Reilly. The TCDT also includes M-113 armored personnel carrier training, pad emergency egress training and a simulated launch countdown. The mission payload aboard Space Shuttle Atlantis is the S3/S4 integrated truss structure, along with a third set of solar arrays and batteries. The crew of six astronauts will install the truss to continue assembly of the International Space Station. Photo credit: NASA/Kim Shiflett