Mission STS-117 Commander Rick Sturckow completes emergency egress procedures during the preparations known as terminal countdown demonstration test.

Mission STS-117 Commander Rick Sturckow completes emergency egress procedures at the 195-foot level of the fixed service structure on Launch Pad 39A during the prelaunch preparations known as terminal countdown demonstration test (TCDT). The TCDT also includes M-113 armored personnel carrier training and payload familiarization. The STS-117 mission is No. 21 to the International Space Station. Mission payloads aboard Atlantis include the S3/S4 integrated truss structure, a third set of solar arrays and batteries. The crew of six astronauts will install the truss to continue assembly of the station. Launch is scheduled for no earlier than March 15. Photo credit: NASA/Kim Shiflett.