On Feb. 20, 1962, NASA astronaut John H. Glenn, Jr. became the first American to orbit the Earth. Scroll through this gallery for behind-the-scenes shots of his historic mission,
In 1960, astronaut John Glenn climbs out of a mockup Mercury capsule during egress training at Langley Research Center.
The Altitude Chamber
Suited up with a ventilation hose attached, Glenn stands at the entrance to the test chamber during an altitude chamber test.
At the U.S. Navy School of Aviation Medicine, John Glenn participates in a disorientation test in the rotating chair.
John Glenn sits for a blood draw by astronaut nurse Delores B. O'Hara, at the Aeromedical Laboratory in Cape Canaveral, Florida.
John Glenn takes the balance mechanism performance test by walking across a narrow board, with his eyes closed and barefoot, in 1962.
Eye-Ear Balance Connection
For additional testing on John Glenn's balance mechanism, a NASA technician runs cool water into Glenn's ear and measures the effect on his eye motions, known as nystagmus.
Learning the Cosmos
In February 1962, during a training event at the Aeromedical Laboratory at Cape Canaveral, John Glenn looks into a Celestial Training Device.
A Moment of Repose
During a pre-flight activity, John Glenn's backup pilot, Scott Carpenter (far left) and Glenn relax after sharing breakfast.
Man in Spacesuit
John Glenn suits up for the Mercury-Atlas 6 flight.
Off for the Launch
Leaving the crew quarters before the Mercury-Atlas 6 mission, astronaut John Glenn, flight surgeon William Douglas and equipment specialist Joe Schmitt make their way to the launch pad. Glenn dons his pressure suit and the portable ventilation unit is seen in his right hand.