Joseph Albert "Joe" Walker (February 20, 1921 – June 8, 1966), flew the first two
spaceplane flights, in 1963, becoming the seventh American
astronaut. Walker was a
Captain in the
United States Air Force, an American
World War II pilot, an
experimental physicist, a
test pilot with
NASA, and a member of the U.S. Air Force
Man In Space Soonest spaceflight program. In 1963, he made two
X-15 experimental rocket aircraft flights beyond the altitude of —the
Kármán line which marks the boundary of
outer space and qualified Walker as an astronaut under both the rules of the U.S. Air Force and of the
Fédération Aéronautique Internationale (FAI).