Joseph A. Walker
Joseph Albert Walker (February 20, 1921 – June 8, 1966) (Capt, USAF) was an American World War II pilot, experimental physicist, NASA test pilot, and astronaut who was the first person to fly an airplane to space. He was one of twelve pilots who flew the North American X-15, an experimental spaceplane jointly operated by the Air Force and NASA. In 1961, Walker became the first human in the mesosphere when piloting Flight 35, and in 1963, Walker made three flights above 50 miles, thereby qualifying as an astronaut according to the United States definition of the boundary of space.