The STS-115 crew members are suiting up for their simulated launch countdown.

The STS-115 crew members are suiting up for their simulated launch countdown. Shown here is Mission Specialist Steven MacLean, who is with the Canadian Space Agency. The mission crew is at KSC for Terminal Countdown Demonstration Test (TCDT) activities that are preparation for launch on Space Shuttle Atlantis, scheduled to take place in a window that opens Aug. 27. The TCDT has included emergency egress training as well as the simulation. During their 11-day mission to the International Space Station, the STS-115 crew will continue construction of the station and attach the payload elements, the Port 3/4 truss segment with its two large solar arrays. Photo credit: NASA/Cory Huston