(07/23/1999) --- STS-93 Commander Eileen M. Collins is checked out by white room closeout crew members before entering the orbiter Columbia. The white room is an environmental chamber at the end of the orbiter access arm that provides entry to the orbiter crew compartment. STS-93 is a five-day mission primarily to release the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. After Space Shuttle Columbia's July 20 and 22 launch attempts were scrubbed, the launch was again rescheduled for Friday, July 23, at 12:24 a.m. EDT. The target landing date is July 27 at 11:20 p.m. EDT