PHOTOS: John Glenn through the years

U.S. President Barack Obama awards a 2012 Presidential Medal of Freedom to astronaut and former U.S. Senator John Glenn during a ceremony in the East Room of the White House in Washington, May 29, 2012 (Reuters)

Former astronaut Senator John Glenn comments on the death of his friend and fellow Mercury 7 astronaut Alan Shepard July 22, 1998. Glenn praised the courage, intelligence and humor of Shepard, who died July 21 at the age of 74 (Reuters)

STS-95 Payload Specialist John Glenn positions himself to take photos from the Space Shuttle Discovery's aft flight deck windows on Flight Day 3 in this NASA handout image dated October 31, 1998. (Reuters/NASA)

Ohio Senator John Glenn gives the thumbs up sign from the cockpit of his T-38 jet aircraft as he arrives at the Kennedy Space Center October 26, 1998. Glenn, 77, blasted off aboard the shuttle Discovery on October 29, becoming the oldest person ever to go into space. (Reuters/NASA)

Mission Specialist John Glenn is helped with his space suit by technicians in the white room at pad 39B at the Kennedy Space Center October 9, 1998, during mock countdown exercises. (Reuters/NASA)

STS-95 crewmember, astronaut and U.S. Senator John Glenn poses for his official NASA photo taken April 14, 1998 (Reuters/NASA)

Ohio Senator John Glenn and Astronaut Stephen Oswald tour the flight deck of the Space Shuttle Columbia during a tour at Kennedy Space Center in this NASA handout image dated January 21, 1998. (Reuters/NASA)

John Glenn, a former astronaut who in 1962 became the first American to orbit the earth, is shown in his spacesuit in NASA photo taken in 1961 or 1962. (Reuters/NASA)