(06/24/1999) --- At the 195-foot level on Launch Pad 39B, STS-93 Mission Specialist Catherine G. Coleman (Ph.D.) leads Mission Specialists Steven A. Hawley (Ph.D.) and Michel Tognini of France, who represents the Centre National d'Etudes Spatiales (CNES), along the yellow-painted path toward the emergency slidewire basket. As part of Terminal Countdown Demonstration Test (TCDT) activities, they are participating in an emergency egress exercise, along with other crew members Commander Eileen M. Collins and Pilot Jeffrey S. Ashby. Collins is the first woman to serve as a Shuttle commander. The crew members have been taking part in the TCDT, which familiarizes them with the mission, provides training in emergency exit from the orbiter and launch pad, and includes a launch-day dress rehearsal culminating with a simulated main engine cut-off. The primary mission of STS-93 is the release of the Chandra X-ray Observatory, which will allow scientists from around the world to obtain unprecedented X-ray images of exotic environments in space to help understand the structure and evolution of the universe. The targeted launch date for STS-93 is no earlier than July 20 at 12:36 a.m. EDT from Launch Pad 39B