KSC-98EC-0597 - STS-91 Commander Precourt participates in TCDT activities STS-91 Mission Commander Charles Precourt participates in Terminal Countdown Demonstration Test (TCDT) activities. The TCDT is a dress rehearsal for launch. STS-91 is scheduled to be launched on June 2 with a launch window opening around 6:10 p.m. EDT. The mission will feature the ninth Shuttle docking with the Russian Space Station Mir, the first Mir docking for Discovery, the conclusion of Phase I of the joint U.S.-Russian International Space Station Program, and the first flight of the new Space Shuttle super lightweight external tank. The STS-91 flight crew also includes Pilot Dominic Gorie and Mission Specialists Wendy B. Lawrence; Franklin Chang-Diaz, Ph.D.; Janet Kavandi, Ph.D.; and Valery Ryumin, with the Russian Space Agency. Andrew Thomas, Ph.D., will be returning to Earth with the crew after living more than four months aboard Mir. 05/06/98