John Herschel Glenn Jr. is an American astronaut, Marine Corps fighter pilot, ordained Presbyterian elder, corporate executive, and politician.
Glenn was the third American to fly in space and the first American to orbit the Earth aboard Friendship 7. He is the oldest person to have entered orbit, having flown into space in 1998 aboard the Space Shuttle Discovery mission STS-95 at age 77. He also served as a United States Senator (D-Ohio) (1974 ? 1999).
Today, Glenn holds an adjunct professorship at both the John Glenn School of Public Affairs and Ohio State’s Department of Political Science.
Source -Wikipedia http://en.wikipedia.org/wiki/John_Glenn