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
Neil Armstrong than most simulations had taken. For this reason, Mission Control was concerned that the LM was running low on fuel. On landing, Aldrin and Armstrong believed they had 40 seconds of fuel left, including the 20 seconds' worth which had to be saved in the event of an abort. During training, Armstrong had, on several occasions, landed the LLTV with fewer than 15 seconds of fuel; he was also confident the LM could survive a fall of up to . Post-mission analysis showed that at touchdown there were 45 to 50 seconds of propellant burn time left. The landing on