STS-91 is the ninth flight of the Shuttle-Mir Phase 1 docking missions.
The crew brought back Andrew Thomas, the last long-duration American
crew member flown on the Russian Space Station Mir. The mission marked
the end of the Shuttle-Mir Phase 1 Program and opened the way for
Phase 2: construction of the International Space Station. The crew
patch depicts the rendezvous of the Space Shuttle Discovery with the
Space Station Mir. The flags of the United States and Russia are displayed
at the top of the patch and both countries are visible on the Earth
behind the two spacecraft. The names of the American crew members
surround the insignia on the outer areas, with the name of Cosmonaut
Valery Ryumin in Cyrillic at the lower right.
The Alpha Magnetic Spectrometer (AMS) is an international payload
planned to fly in the payload bay of Discovery. Two thin golden streams
flowing into the AMS represent charged elementary particles. The detection
of antimatter in space will help scientists better understand the
physics and origins of the universe.