(06/24/1999) -- The STS-93 crew pauses at the launch pad for a photograph before heading for Space Shuttle Columbia (in the background) and a launch-day dress rehearsal. From left are Mission Specialist Michel Tognini of France, who represents the Centre National d'Etudes Spatiales (CNES), Pilot Jeffrey S. Ashby, Commander Eileen M. Collins, and Mission Specialists Steven A. Hawley (Ph.D.) and Catherine G. Coleman (Ph.D.). Collins is the first woman to serve as a Shuttle commander. The crew members have been taking part in a Terminal Countdown Demonstration Test, which familiarizes them with the mission, provides training in emergency exit from the orbiter and launch pad, and includes the 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