The seven original American astronauts were Alan B. Shepard, Virgil I. (Gus) Grissom, John H. Glenn, M. Scott Carpenter, Walter M. Wally) Schirra, L. Gordon Cooper, and Donald K. (Deke) Slayton. NASA introduced the astronauts in Washington DC on 9 April 1959. Sometimes known as the Mercury Seven, or the Seven Original Astronauts, they piloted the manned spaceflights of the Mercury program from May 1961 to May 1963. Three of the astronauts were Air Force pilots (Grissom, Cooper, and Slayton); three were Navy pilots (Shepard, Carpenter, and Schirra), and one was a Marine Corps pilot (Glenn).