STS-76 was NASA's 76th Space Shuttle mission, and the 16th mission for Atlantis. STS-76 launched on 22 March 1996 at 3:13 am EST (UTC −5) from Kennedy Space Center launch pad 39B. STS-76 lasted over 9 days, traveled about 3,800,000 miles (6,100,000 km) while orbiting Earth an estimated 145 times, and landing at 5:28 am PST (UTC −8) on 31 March 1996 at Edwards Air Force Base runway 22.
The flight was the third Shuttle mission to dock with the Russian Space Station Mir, as part of the Shuttle-Mir Program, carrying astronaut Shanon Lucid to the orbital laboratory to replace NASA astronaut Norm Thagard. STS-76 also carried a SPACEHAB single module along with Lucid, and on flight day 6 Linda Godwin and Michael R. Clifford performed the first U.S. spacewalk around two docked spacecraft.
Mir EO-21 was a long-duration mission aboard the Russian Space station Mir, which occurred between February and September 1996. The crew consisted of two Russian cosmonauts, Commander Yuri Onufrienko and Yury Usachov, as well as American astronaut Shannon Lucid. Lucid arrived at the station about a month into the expedition, and left about a week following its conclusion; NASA refers to her mission as NASA-2. She was the second American to have a long-duration stay aboard Mir, the first being Norman Thagard, as a crew member of Mir EO-18; he stayed on the station for 111 days. Some sources refer to her mission as Mir NASA-1, claiming that she was the first American to have a long-duration stay aboard Mir.