On This Day in History / April 2, 2024 1959: Out of 110 candidates, NASA selected The Mercury Seven (top left to bottom right): Walter M. Schirra jr. Alan B. Shepard jr. John H. Glenn, M. Scott Carpenter, Donald K. Slayton, L. Gordon Cooper, Virgil I. Grissom. Cooper, Grissom, and Slayton were USAF captains.