(03/19/2002) -- STS-110 crew members practice emergency exit from the Fixed Service Structure during Terminal Countdown Demonstration Test. From left are Mission Specialists Jerry L. Ross, Lee M.E. Morin and Steven L. Smith. TCDT also includes a simulated launch countdown and is held at KSC prior to each Space Shuttle flight. Scheduled for launch April 4, the 11-day mission will feature Shuttle Atlantis docking with the International Space Station (ISS) and delivering the S0 truss, the centerpiece-segment of the primary truss structure that will eventually extend over 300 feet