This Day in History: NASA and the first untethered spacewalk

During this week in 1984, a NASA astronaut makes the first untethered spacewalk. No one had ever done such a thing before! Usually, a long cable keeps astronauts safely bound to their spacecraft. But now Captain Bruce McCandless II would leave the Space Shuttle Challenger and float freely in space, relying only on a propulsion system strapped to his back.

McCandless had been in Mission Control when Neil Armstrong accomplished a similar feat on the moon’s surface. Now, nearly 15 years later, it was his turn.

“It may have been one small step for Neil,” McCandless joked as he left the Space Shuttle that day. “But it’s a heckuva big leap for me.”

Those in Mission Control fell apart laughing at the comment. “Which was sort of what I had intended,” McCandless later said, “because I wanted to loosen things up a little.”

And who could blame him? McCandless was relying solely on a 300-lb nitrogen-propelled backpack to maneuver himself through space. What if the suit’s nitrogen propulsion system failed? What if he had problems communicating with those still aboard the Space Shuttle? He’d had 300 hours of practice to prepare him for that moment, but a lot could still go wrong.

Indeed, on February 6, the day before the planned walk, the Space Shuttle crew had drastically increased oxygen levels in the shuttle. They needed to drive the nitrogen out of McCandless’s bloodstream. No one wanted him getting the bends in space. The next morning, as McCandless prepared to leave, anticipation had reached a fever pitch.

“You’re ready. Go, go, go!” the crew cheered as McCandless left the shuttle. “I don’t like those overused lines ‘slipped the surly bonds of Earth,’” McCandless later wrote, “but when I was free from the shuttle, they felt accurate. It was a wonderful feeling . . . .”

His biggest problem, as it would turn out, was the temperature. McCandless was so cold that his teeth were chattering! “I was out away from the payload bay,” he later explained, “so I wasn’t getting any heat reflected back into the pressure suit. . . . The suit was designed to support someone doing honest physical work in the space environment, and flying the manned maneuvering unit was a matter of using your fingertips. So, my metabolic load was extremely low, and I got cold.”

While McCandless floated in space, crew member Robert Gibson snapped pictures. “I had the gold sun visor down,” McCandless later said. “So that in principle, people could imagine themselves inside of there instead of me.”

One person did more than imagine it: Astronaut Robert L. Stewart also took the manned maneuvering unit (MMU) out for a spin that day. A few other astronauts would make similar spacewalks later that year.

The Challenger disaster a few years later unfortunately put the MMUs out of use; a post-Challenger safety review determined that their use was simply too risky.

Maybe the astronauts would have continued on, if they’d been allowed? “I relaxed and looked around,” one astronaut later said of his MMU experience, “and saw the shuttle coming up behind me, and [a satellite to repair] in front of me, and the Earth going by underneath, and I thought, ‘Jeez, I can’t believe they let me do this!’”