Glenn flew NASA's Friendship 7, a Mercury-Atlas 6 spacecraft, to about 162 miles in altitude, going at a maximum orbital velocity of about 17,500 miles per hour. This mission orbited the Earth 3 times and lasted 4 hours, 55 minutes, and 23 seconds, from launch to impact in the Atlantic Ocean. This was the first US manned orbital mission.

Glenn was born on July 18, 1921, in Cambridge, Ohio. He graduated from Muskingum College in New Concord, Ohio, receiving a Bachelor of Science degree in engineering. He and Anna Margaret Castor married, and they had two children. In 1943, Glenn was commissioned in the Marine Corps and joined Marine Fighter Squadron 155; he flew F-4U fighter planes on 59 combat missions in the Marshall Islands (in the Pacific Ocean) during World War 2. He also flew 63 missions with Marine Fighter Squadron 311 during the Korean War. After attending the Naval Air Test Center at Patuxent River, Maryland, Glenn became a test pilot. Glenn retired a Colonel in the US Marine Corps on January 1, 1965.

Glenn was the US Senator from Ohio from November, 1974 until January, 1999. In 1998, 36 years later, Glenn flew a 9-day mission on the Space Shuttle STS-95 Discovery (October 29 to November 7, 1998). During this mission, the crew and spacecraft orbited the Earth 134 times, traveling 3.6 million miles in 213 hours and 44 minutes.