(04/27/1998) --- The orbiter Discovery approaches the door of KSC's Vehicle Assembly Building after leaving the Orbiter Processing Facility Bay 2. Soon, it will be hoisted upright into a vertical position to be mated with an orange external tank and two white solid rocket boosters. Once mated, the orbiter becomes the Space Shuttle Discovery, slated for launch on STS-91, the ninth and final docking mission with the Russian Space Station Mir. The six-member crew of STS-91 will dock with Mir and pick up Mission Specialist Andrew Thomas, Ph.D., who will have been on Mir about four months, to return him to Earth. STS-91 is scheduled to launch June 2 at about 6:04 p.m. EDT