The oldest astronaut is John Glenn Jr. (USA, b. 18 July 1921), who was 77 years 103 days old when he was launched into space as part of the crew of Discovery STS-95 on 29 October 1998. The mission lasted 11 days, landing on 7 November 1998.
Senator Glenn was one of the first US astronauts to fly with the Mercury orbiter space programme. In February 1962 he completed a five hour, three-orbit flight aboard Friendship 7.