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
Spence M. Armstrong Force Base. After two years in flight test, Armstrong prepared for a combat tour in Southeast Asia by completing F-105 combat crew training at McConnell Air Force Base, Kansas. He was assigned to the 34th Fighter Squadron based at Korat Royal Thai Air Force Base, Thailand where he flew 100 combat missions in the F-105. In July 1968, Armstrong returned to flight test as an instructor and later as the deputy commandant at the Aerospace Research Pilot School. In August 1971, Armstrong attended the Air War College at Maxwell Air Force Base, Alabama and graduated in May 1972. After a