Mercury Program astronauts, wearing civilian clothes, sit in Mercury capsules / Virgil 'Gus' Grissom, Scott Carpenter, Walter Schirra, Jr., John Glenn, Jr, L Gordon Cooper, Jr, Donald 'Deke' Slayton, and Alan Shepard on January 01, 1961...

Engineers and technicians working on Project Mercury capsules on January 01, 1960 (Footage by Getty Images)

Mercury Program astronauts training in classroom and conducting survival training in the desert at Stead Air Force Base on July 01, 1960 in Reno, Nevada (Footage by Getty Images)

Spectators looking through binoculars and telescopes, eagerly awaiting Mercury Atlas 6 launch / television camera crews covering the event / banner saying, 'The Voice of America' / sign for ABC Radio News / Mercury rocket is launched...

Helicopters and naval ship assist with recovery of Mercury Freedom 7 capsule on May 05, 1961 (Footage by Getty Images)

Project Mercury, MA-7, MA-8 and MA-9: L Gordon Cooper suits up during Mercury Atlas 7 mission, brief shot in MCC / liftoff and ascent / spectators watching / Wally Schirra during onboard film of Mercury Atlas 8 / Earth view / capsule in...

helicopters recover Mercury Freedom 7 space capsule / Alan Shepard, first American in space, after the recovery on May 05, 1961 (Footage by Getty Images)

Mercury 7 Program astronauts in training classroom / CU John Glenn / L Gordon Cooper pointing on January 01, 1961 (Footage by Getty Images)

Mercury 7 astronauts wearing flight suits and posing for photographs in front of Convair 106-B aircraft / They are, left to right, M Scott Carpenter, L Gordon Cooper Jr, John Glenn Jr, Virgil Grissom, Walter M Schirra Jr, Alan B Shepard...

Project Mercury astronaut John Glenn as seen from onboard camera, Mercury Control Center tracking chart and countdown clock. Astronaut John Glenn in Project Mercury capsule on February 20, 1962 in Space (Footage by Getty Images)

Mercury Program astronauts deplaning from American Airlines airplane, wearing suits and posing for photographs on January 01, 1961 (Footage by Getty Images)

Prince Philip Visits Manned Space Craft Center in Houston, Texas / EXT Manned Space Craft Center in Houston / Prince Philip arrives / large crowd hover around the prince as he inspects a Mercury space capsule / Prince Philip stands with...

NASA control room at Cape Canaveral for Project Mercury / various CU engineers /CU clocks and monitors / spotlights at night as final preparations are made at launch pad / truck of liquid oxygen loading contents onto missile / United...

Astronaut John Glenn waves to the crowd before entering the elevator to the Friendship 7.

US Air Force airplane on tarmac / Mercury Program astronauts in zero gravity / Gus Grissom at flight controls on January 01, 1961 (Footage by Getty Images)

Project Mercury Redstone 4 rocket on launch pad / Virgil 'Gus' Grissom suited up, climbs into Liberty Bell 7 space capsule / spacecraft is launched / spectators taking pictures on July 21, 1961 in Cape Canaveral, Florida (Footage by...

Banners in Cocoa Beach welcoming John Glenn home, 'Welcome Back John' / cheering people along parade route road, waving American flags / ceremony at Manned Space Center in Houston, Texas, honoring John Glenn / President John Kennedy...

Astronauts Alan Shepard and John Glenn eating breakfast before Project Mercury III mission on July 28, 1961 in Cape Canaveral, Florida (Footage by Getty Images)