(06/23/1999) --- The STS-93 crew poses for a photo on Launch Pad 39B during a break in Terminal Countdown Demonstration Test (TCDT) activities. From left are Commander Eileen M. Collins, Pilot Jeffrey S. Ashby, and Mission Specialists Steven A. Hawley (Ph.D.), Michel Tognini of France, who represents the Centre National d'Etudes Spatiales (CNES), and Catherine G. Coleman (Ph.D.). Collins is the first woman to serve as a Shuttle commander. Behind them is the Space Shuttle Columbia, with only the solid rocket boosters and external tank showing, on the mobile launcher platform. In preparation for their mission, the STS-93 crew members are participating 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