Mercury 7 astronauts at a press conference. The astronauts are Alan B. Shepard, Walter M. Schirra, and John H. Glenn, Virgil I. Grissom, M. Scott Carpenter, Donald Slayton, and L. Gordon Cooper. This group of astronauts, also known as the Original Seven and Astronaut Group 1, are the only astronauts to have flown on all of NASA's manned spacecraft in the 20th century.