STS-91 Mission Specialists Franklin Chang-Diaz, Ph.D., and Janet Kavandi, Ph.D., participate in the Crew Equipment Interface Test, or CEIT, inside an airlock in KSC's Orbiter Processing Facility Bay 2. During CEIT, the crew have an opportunity to get a hands-on look at the payloads with which they'll be working on-orbit. The STS-91 crew are scheduled to launch aboard the Shuttle Discovery for the ninth and final docking with the Russian Space Station Mir from KSC's Launch Pad 39A on May 28 at 8:05 EDT KSC-98pc461

The Space Shuttle program was the United States government's manned launch vehicle program from 1981 to 2011, administered by NASA and officially beginning in 1972. The Space Shuttle system—composed of an orbiter launched with two reusable solid rocket boosters and a disposable external fuel tank— carried up to eight astronauts and up to 50,000 lb (23,000 kg) of payload into low Earth orbit (LEO). When its mission was complete, the orbiter would re-enter the Earth's atmosphere and lands as a glider. Although the concept had been explored since the late 1960s, the program formally commenced in 1972 and was the focus of NASA's manned operations after the final Apollo and Skylab flights in the mid-1970s. It started with the launch of the first shuttle Columbia on April 12, 1981, on STS-1. and finished with its last mission, STS-135 flown by Atlantis, in July 2011.