On February 20, 1962, John Glenn climbed into the Friendship 7 capsule on top of an Atlas rocket, a missile that, in test flights, had a habit of exploding on the pad. The 4-hour, 55-minute mission circled the Earth three times. During the flight, a sensor warned Mission Control that his heat shield might be loose; if it came off during reentry, he'd burn alive. They told him to keep his retrorocket pack attached as a backup, and somehow it held. He came home a national hero, eventually becoming a U.S. senator. In 1998 at age 77, he went back to space on the Space Shuttle Discovery, the oldest person ever to leave Earth.