Stock Photo - 04/06/2000 __ As part of Terminal Countdown Demonstration Test TCDT activities, STS_101 Mission Specialist Jeffrey N. Williams takes the driver seat in an M_113 personnel carrier during emergency egress training at Launch pad 39A. The TCDT also includes a simulated launch countdown and familiarization with the payload. Other crew members taking part are Commander James D. Halsell Jr., Pilot Scott J. Doc Horowitz and Mission Specialists Mary Ellen Weber James Voss, Susan Helms, and Yury Usachev of Russia. During their mission to the International Space Station, the STS_101 crew will be delivering logistics and supplies, plus preparing the Station for the arrival of the Zvezda Service Module, expected to be launched by Russia in July 2000. Also, the crew will conduct one space walk to perform maintenance on the Space Station. This will be the third assembly flight for the Space Station. STS_101 is scheduled to launch April 24 at 4:15 p.m. from Launch Pad 39A