Footnotes

Neil Armstrong is pictured after completing a flight in the X-15 aircraft in November 1960. At the time, Armstrong was a research pilot for NASA's Flight Research Centre at Edwards Air Force Base, California.
Dressed in a silver pressure suit, Armstrong stands beside the sleek, black X-15 aircraft, helmet in hand. His expression is serious yet composed, reflecting the calm demeanour and focus required for such daring experimental missions. The X-15 program, in which Armstrong was a key participant, was crucial in gathering data on high-speed flight and atmospheric re-entry, paving the way for future manned space missions. During one of his flights on April 5, 1960, Armstrong reached an altitude of 179,000 feet—one of the highest ever achieved by the X-15—demonstrating the daring nature of the early flights that pushed the boundaries of aerospace technology. Armstrong began his career with NASA's predecessor, the National Advisory Committee for Aeronautics (NACA), in 1955 at the Lewis Flight Propulsion Laboratory in Cleveland, Ohio. Later, he transferred to the High-Speed Flight Station at Edwards, California, becoming both an aeronautical research scientist and a test pilot. His colleagues recognized Armstrong's exceptional technical expertise and aptitude early on. X-15 pilot Milt Thompson once remarked that Armstrong was "the most technically capable of the early X-15 pilots", while fellow pilot Bill Dana noted, "he had a mind that absorbed things like a sponge". These qualities were foundational to his selection for the second group of NASA astronauts on September 17, 1962, long before his historic Apollo 11 mission made him a global icon.