The crew on mission STS-100 poses in the White Room during Terminal Countdown Demonstration Test activities.

The crew on mission STS-100 poses in the White Room during Terminal Countdown Demonstration Test activities. Standing, from left, are Mission Specialists Scott E. Parazynski, Yuri Lonchakov, and Umberto Guidoni; Pilot Jeffrey S. Ashby; Commander Kent V. Rominger; Mission Specialist Chris A. Hadfield; and Mission Specialist John L. Phillips. The TCDT includes emergency escape training, payload bay walkdown, and a simulated launch countdown. Launch of Space Shuttle Endeavour on mission STS-100 is targeted for April 19 at 2:41 p.m. EDT from Launch Pad 39A