Launched from Cape Canaveral atop an Atlas rocket, Glenn's Mercury capsule Friendship 7 completed three orbits at roughly 17,500 mph, restoring American confidence badly shaken by Soviet spaceflight firsts. A sensor falsely indicated his heat shield was loose, prompting ground controllers to leave the retrorocket pack attached during reentry as a precaution, adding a tense final descent to an otherwise triumphant flight.
Glenn had waited through ten scrubbed launch attempts, strapped into the tiny capsule for hours at a stretch while weather or mechanical gremlins forced delays. When the countdown finally held on February 20, the Atlas rocket—a temperamental machine that had exploded on earlier test flights—carried him off the pad at 9:47 a.m. with the words "Godspeed, John Glenn" ringing from launch control.
In orbit he watched sunsets compress into minutes and reported strange luminous specks drifting past his window, which he nicknamed "fireflies"—later identified as ice particles shaken loose from the spacecraft's exterior. Midway through the flight, a telemetry signal suggested the heat shield and its landing bag had come loose, a potentially fatal problem during reentry's 3,000-degree heat. Mission Control, led by Christopher Kraft, told Glenn to keep the spent retrorocket package strapped on to help hold the shield in place, without telling him the full extent of their fear.
He splashed down safely in the Atlantic after 4 hours and 55 minutes aloft. The flight came less than a year after Yuri Gagarin's and Alan Shepard's, but it made Glenn a national hero, celebrated with a ticker-tape parade and, decades later, a return to space in 1998 at age 77.
Key people: John Glenn, Christopher Kraft