(01/13/2000) -- In the bunker at Launch Pad 39A, the STS-99 crew try on oxygen masks. From left are Pilot Dominic Gorie, Mission Specialist Janice Voss (Ph.D.), Commander Kevin Kregel, and Mission Specialists Mamoru Mohri, Janet Lynn Kavandi (Ph.D.) and Gerhard Thiele. Mohri is with the National Space Development Agency (NASDA) of Japan and Thiele is with the European Space Agency. The crew are taking part in Terminal Countdown Demonstration Test activities, which provide them 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