John Glenn was an astronaut for NASA.
John Herschel Glenn Jr. ( July 18 , 1921 -- December 8 , 2016 ) was a United States Marine Corps aviator , engineer , astronaut , and United States Senator from Ohio . He was one of the Mercury Seven , military test pilots selected in 1959 by NASA as the United States ' first astronauts . The Mercury Seven were the group of seven Mercury astronauts announced by NASA on April 9 , 1959 . These seven original American astronauts were Scott Carpenter , Gordon Cooper , John Glenn , Gus Grissom , Wally Schirra , Alan Shepard , and Deke Slayton .