STS-89 "Endeavour" (January 22–31, 1998), was the eighth Shuttle-Mir docking mission during which the crew transferred more than 9,000 pounds of scientific equipment, logistical hardware and water from Space Shuttle "Endeavour" to Mir. In the fifth and last exchange of a U.S. astronaut, STS-89 delivered Andy Thomas to Mir and returned with David Wolf. Mission duration was 8 days, 19 hours and 47 seconds, traveling 3.6 million miles in 138 orbits of the Earth. Dunbar was the Payload Commander, responsible for all payload activities including the conduct of 23 technology and science experiments.