Man In Space Soonest (MISS) was a United States Air Force (USAF) program to put a man into outer space before the Soviet Union did. The program was cancelled on August 1, 1958, and was replaced by NASA's Project Mercury. Only two men from the program would actually reach outer space. The first, Joseph A. Walker, did so twice in two X-15 rocket plane tests in 1963. Another, Neil Armstrong, became a NASA astronaut in 1962 and became the first person to walk on the Moon in 1969.