Project Mercury also excluded civilian NASA X-15 pilot Neil Armstrong, though he had been selected by the US Air Force in 1958 for its Man In Space Soonest program, which was replaced by Mercury. Although Armstrong had been a combat-experienced NAP during the Korean War, he left active duty in 1952. Armstrong became NASA's first civilian astronaut in 1962 when he was selected for NASA's second group, and became the first man on the Moon in 1969. It was further stipulated that candidates should be between 25 and 40 years old, no taller than , and hold a college degree in a
Joseph A. Walker Medal with seven oak leaf clusters. After World War II, Walker separated from the Army Air Force and joined the National Advisory Committee for Aeronautics (NACA) Aircraft Engine Research Laboratory in Cleveland, Ohio, as an experimental physicist. While in Cleveland, Walker became a test pilot, and he conducted icing research in flight, as well as in the NACA icing wind tunnel. He transferred to the High-Speed Flight Research Station in Edwards, California, in 1951. Walker served for 15 years at the Edwards Flight Research Facility - now called the Neil A. Armstrong Flight Research Center. By the mid-1950s, he was