On February 7, 1984, NASA astronaut Bruce McCandless II performed the first untethered spacewalk.

An incredible photograph of the event shows McCandless floating in space, entirely alone, with Earth some 250 miles below.

McCandless used a Manned Maneuvering Unit (MMU) — a nitrogen-propelled, hand-controlled backpack — to carry himself 300 feet (about 90 meters) from the space shuttle Challenger that had brought him to orbit on the STS-41B mission.

“It may have been one small step for Neil, but it’s a heck of a big leap for me,” McCandless quipped shortly before attempting the feat.

In an article marking the 40th anniversary of the 82-minute solo adventure, NASA said that many agency officials had been concerned about the use of a self-propelled backpack in space, adding that spacewalkers usually used special cables to connect themselves to the shuttle, in the same way that those at the International Space Station conduct spacewalks today.

Up until his death in 2017 at the age of 80, McCandless was often asked about the unusual experience, which was captured on film by NASA astronaut Robert L. Gibson using a Hasselblad camera.

“I was grossly over-trained,” Boston-born McCandless said. “I was just anxious to get out there and fly. I felt very comfortable … It got so cold my teeth were chattering and I was shivering, but that was a very minor thing.”

McCandless said that he’d been told of “the quiet vacuum you experience in space but with three radio links saying, ‘How’s your oxygen holding out?’, ‘Stay away from the engines!’ and ‘When’s my turn?’, it wasn’t that peaceful.”

But he also said the experience was “a wonderful feeling, a mix of personal elation and professional pride. It had taken many years to get to that point.”

A couple of hours after McCandless’s flight, fellow astronaut Robert Stewart used the backpack to perform the same feat and become the second person to fly untethered in space.