First US spacewalk 50th anniversary: Nasa astronaut Ed White stepped into the void from Gemini 4

Humans have delved deeper into space than was ever thought possible, revolutionising our understanding of the void and uncovering its surprises and secrets. Fifty years ago today (3 June), in the midst of the space race between the United States and Russia, the US marked another great achievement on our outward journey – when Nasa's Edward White became the first American to walk in space.

Astronauts Ed White and James "Jim" McDivitt circled the Earth 66 times in four days during the Gemini IV mission in June 1965. Yet the highlight of the mission was the first spacewalk by White – who floated free outside the spacecraft, linked to the craft by a tether, for 23 minutes.

White was selected as the pilot of Gemini IV by Nasa as one of an elite group of astronauts for the mission. At 3.45pm on 3 June, White opened the hatch and used a hand-held oxygen-jet manoeuvring gun to push himself out of the capsule into the weightlessness of space above the Earth's atmosphere.

A defect in the capsule's hatch-latching mechanism caused difficulties its opening and closing, which delayed the start of the extravehicular activity (EVA) and put White and McDivitt's safe return to Earth at risk.

Initially, White propelled himself to the end of the 8m tether and back to the craft three times using the hand-held gun before the fuel ran out. White was able to shift into position by twisting his body and pulling on the tether.

While he was outside, a spare thermal glove floated away through the open hatch and became an early piece of space debris in low Earth orbit. It eventually burned up as it re-entered the Earth's atmosphere.

White hovered above the Pacific Ocean, near Hawaii, when the EVA began, but ended up over the Gulf of Mexico by the time he got back inside the spacecraft. According to Nasa, he found the experience so exhilarating he was reluctant to get back into the craft, and had to be ordered back in. "I'm coming back in... And it's the saddest moment of my life," he said, while re-entering.

White, along with fellow astronauts Virgil "Gus" Grissom and Roger Chaffee, died during pre-launch testing for the first manned Apollo mission at Cape Canaveral in 1967. He was awarded the Nasa Distinguished Service Medal for his mission in Gemini IV and awarded the Congressional Space Medal of Honour posthumously.

Russian cosmonaut Alexei Leonov was the first human to perform a space walk on 18 March 1965.