Astronaut Ed White became the first American to walk in space on this day in history, June 3, 1965.
White, an engineer, a Lieutenant Colonel in the U.S. Air Force, a test pilot and NASA astronaut, made the spacewalk — technically known as "Extravehicular Activity" or "EVA" — while serving as the pilot on the Gemini 4 mission.
Command pilot James McDivitt was the other member of the crew, and took pictures of White outside the vehicle.
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White spent about 20 minutes floating outside the Gemini 4 capsule, nearly double the time initially allowed by NASA for the spacewalk.
"Initially, White propelled himself to the end of the 8-meter tether and back to the spacecraft three times using the hand-held gun," NASA's website says.
White was the first person to use this type of propulsion, a hand-held maneuvering unit, in a spacewalk.
However, the fuel for the propulsion gun ran out three minutes into the spacewalk, forcing White to get around by "twisting his body and pulling on the tether," said NASA.
Fueling situation aside, White relished the experience.
"I feel like a million dollars," White said upon beginning his spacewalk, according to NASA.
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While on the spacewalk, White took pictures of Earth from 103 miles over its surface, and was reportedly extremely reluctant to return to the capsule.
"This is the greatest experience," said White. "It's just tremendous."
Back on Earth, the professionals at mission control were just a hair more concerned about White's safety, the NASA website notes.
"Gemini 4, get back in," Virgil "Gus" Grissom reportedly yelled at White.
Grissom, a fellow astronaut, was serving as "CapCom" during Gemini 4.
White initially pushed back against the request to end the spacewalk, saying he was "doing great" and that the experience was "fun" before he gave in, NASA revealed.
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"I’m coming back in … and it’s the saddest moment of my life," said White when he finally agreed to reenter the capsule.
In addition to the first U.S. EVA, Gemini 4 was another milestone mission in NASA's history. It was the first multi-day space flight by the United States, although it was shorter than a previous Soviet space flight.
It also was the first U.S. spaceflight in which astronauts performed experiments.
White's EVA was considerably smoother than that of the first-ever EVA.
On March 18, 10 weeks before White's spacewalk, Soviet cosmonaut Alexei Leonov made the first spacewalk as part of the Voskhod 2 mission, according to the website for the European Space Agency.
He almost didn't make it back.
Leonov's spacesuit expanded in space — so much so that he could not fit through the door back into the capsule after his 12 minutes outside the vehicle.
Making "a hair-raising decision, he opened a valve on the suit to let enough air escape for him to enter the airlock," said the European Space Agency.
As for astronaut White, his time came to a sudden and tragic end less than two years after his historic spacewalk.
White, along with fellow astronauts Grissom and Roger B. Chaffee, died on Jan. 27, 1967, when their cabin caught fire during a launch rehearsal test of the Apollo 1 mission.
White was laid to rest at West Point Cemetery in New York with full military honors, said the National Air and Space Museum's website.
During his spacewalk, White experienced something other-worldly. He confided later to his friend, the Reverend Jackson Downey of First Methodist Church in Cocoa Beach, Florida, that out there alone in space, he’d sensed "the presence of God," according to Christian website Crosswalk.com.
In 2015, on the 50th anniversary of his spacewalk, White was posthumously awarded NASA's Ambassador of Exploration Award.
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"In many ways, Ed’s spacewalk was the modern-day equivalent of Lewis and Clark’s portage across the Gates of the Mountains during exploration of the West. He had ventured into uncharted territory," said NASA Deputy Administrator Dava Newman in 2015 at the ceremony honoring White, according to the National Air and Space Museum's site.
"That historical achievement is a big part of the reason why Mars is now within our sights, and we will continue to push EVA technological advancements as we move forward on our journey to Mars."