Don Leslie Lind, Ph.D. is an American scientist and a former naval officer and aviator, and NASA astronaut. He graduated from the University of Utah with an undergraduate degree in physics in 1953. Following his military service obligation, he earned a Ph.D. in high-energy nuclear physics from the University of California, Berkeley in 1964. Lind was a naval aviator and attained the rank of Commander in the United States Naval Reserve. He had active duty in San Diego and aboard the carrier USS Hancock. After completing his doctorate, Lind worked at NASA's Goddard Research Center from 1964 to 1966. During this period, he applied for the third group of astronauts but did not have enough flight hours. He applied for the fourth group, but was denied for being too old. The age restriction was raised for the fifth group, and he was selected with the Original Nineteen in 1966. Lind helped to develop the Apollo 11 EVA activities, and served as CAPCOM for the Apollo 11 and Apollo 12 missions. He was then assigned as backup Pilot for Skylab 3 and Skylab 4 and nearly flew on the proposed Skylab Rescue mission. Lind was the Payload Commander on his only flight, STS-51-B, launched April 29, 1985. He designed an experiment to capture the Earth's aurora. The payload experiments consisted primarily of microgravity research and atmospheric measurement. The Orbiter Challenger completed 110 orbits before landing at Edwards Air Force Base, California.