John Herschel Glenn, Jr. (born July 18, 1921) is a former United States Marine Corps pilot, astronaut and United States senator who was the first American to orbit the Earth and third American in space. Glenn was a Marine Corps fighter pilot before joining NASA's Mercury program as a member of NASA's original astronaut group. He orbited the Earth in Friendship 7 in 1962. After retiring from NASA, he entered politics as a Democrat and represented Ohio in the United States Senate from 1974 to 1999.
Glenn received a Congressional Space Medal of Honor in 1978. He was inducted into the Astronaut Hall of Fame in 1990. On October 29, 1998, he became the oldest person to fly in space, and the only one to fly in both the Mercury and Space Shuttle programs, when at age 77, he flew on Discovery (STS-95). Glenn and M. Scott Carpenter are the last surviving members of the Mercury Seven.
John Glenn was born in Cambridge, Ohio, to John Herschel Glenn Sr. and Teresa (née Sproat). He was raised in New Concord, Ohio. Glenn studied mathematics at Muskingum College, and received his private pilot's license as physics course credit in 1941. When the attack on Pearl Harbor brought the United States into World War II, he dropped out of college and enlisted in the U.S. Army Air Corps; however, the Army did not call him up, and in March 1942 he enlisted as a United States Navy aviation cadet. He trained at Naval Air Station Olathe, where he made his first solo flight in a military aircraft. In 1943, during advanced training at the Naval Air Station Corpus Christi, he was reassigned to the United States Marine Corps. After completing his training, Glenn was assigned to Marine squadron VMJ-353, flying R4D transport planes. He eventually managed a transfer to VMF-155 as an F4U Corsair pilot, and flew 59 combat missions in the South Pacific. He saw action over the Marshall Islands, where he attacked anti-aircraft batteries and dropped bombs on Maloelap. In 1945, he was assigned to Naval Air Station Patuxent River, Maryland, where he was promoted to captain shortly before the war ended. Glenn flew patrol missions in North China with the VMF-218 squadron, until it was transferred to Guam. He became a flight instructor at Naval Air Station Corpus Christi, Texas, in 1948, then attended the amphibious warfare school and received a staff assignment.