Project Mercury astronauts. Group portrait of the seven astronauts selected for Project Mercury in 1959. They are: (front row, l-r) Walter Schirra, Donald 'Deke' Slayton, John Glenn, Scott Carpenter, (back row, l-r) Alan Shepard, Virgil 'Gus' Grissom and Gordon Cooper. Shepard was the first of the group (and the first ever American) into space, his sub-orbital flight taking place on 5 May 1961. He was followed by Grissom (sub- orbital), Glenn (first orbital flight), Carpenter, Schirra and Cooper. Cooper's was the last Mercury flight, launched on 15 May 1963. Slayton had to wait until the 1975 Apollo-Soyuz Test Project mission to get into space.