John Glenn (b. 1922) is a retired astronaut who was a member of NASA's initial group of space explorers -- the Mercury Seven. He was the first American to complete a full Earth orbit and the third American in space. After retiring from NASA, Glenn went into politics and served as a U.S. senator from Ohio for 25 years. Glenn is also the oldest person to fly in space. In 1998, while still a sitting senator, a 77-year-old Glenn flew as a Payload Specialist on the Space Shuttle Discovery (STS-95).
"The most important thing we can do is inspire young minds and to advance the kind of science, math and technology education that will help youngsters take us to the next phase of space travel." [Wikiquote]
As quoted in "Space All systems go for National Space Day" at CNN (4 May 2000); also at John Glenn Friendship 7 Day