STS-50 "Columbia" (June 25 to July 9, 1992). Dunbar was the Payload Commander on STS-50, the United States Microgravity Lab-1 mission which was dedicated to microgravity fluid physics and materials science. Over 30 experiments sponsored by over 100 investigators were housed in the Spacelab in the Shuttle's Payload Bay. A payload crew of four operated around-the-clock for 13 days performing experiments in scientific disciplines such as protein crystal growth, electronic and infrared detector crystal growth, surface tension physics, zeolite crystal growth, and human physiology. Mission duration was 13 days, 19 hours, 30 minutes and 4 seconds, traveling 5.7 million miles in 221 orbits of the Earth.