In 1964, Glenn left NASA to enter the politics, though it would be another decade before he was elected to the Senate.

But Glenn’s career in space didn’t end there. In 1998, at age 77, he became the oldest man to fly in space. Traveling with six Discovery crew mates, Glenn volunteered to become a human guinea pig for tests on the aging process in astronauts.

“Boy, enjoying the show. This is beautiful. It’s still a trite old statement: Zero-G and I feel fine,” Glenn reportedly told Houston Mission Control three hours into the flight.

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