The STS-99 crew pose for a photograph during Terminal Countdown Demonstration Test TCDT activities.

At the 167-foot level of the Fixed Service Structure on Launch Pad 39A, the STS-99 crew pose for a photograph during Terminal Countdown Demonstration Test (TCDT) activities. Standing left to right are Mission Specialist Janet Lynn Kavandi (Ph.D.), Commander Kevin Kregel, Mission Specialists Janice Voss (Ph.D.), Gerhard Thiele and Mamoru Mohri, and Pilot Dominic Gorie. Thiele is with the European Space Agency and Mohri is with the National Space Development Agency (NASDA) of Japan. Behind them (left) are visible the top of a solid rocket booster (white) and external tank (orange). The TCDT provides the crew with simulated countdown exercises, emergency egress training, and opportunities to inspect the mission payloads in the orbiter's payload bay. STS-99 is the Shuttle Radar Topography Mission, which will chart a new course, using two antennae and a 200-foot-long section of space station-derived mast protruding from the payload bay to produce unrivaled 3-D images of the Earth's surface. The result of the Shuttle Radar Topography Mission could be close to 1 trillion measurements of the Earth's topography. Besides contributing to the production of better maps, these measurements could lead to improved water drainage modeling, more realistic flight simulators, better locations for cell phone towers, and enhanced navigation safety. Launch of Endeavour on the 11-day mission is scheduled for Jan. 31 at 12:47 p.m. EST