What happens when humans spend more than 84 days in space? One time, they just took a day off.

On this day in 1974, the last Skylab mission finished. It marked the end of what was then the longest amount of time humans had spent in space, on the space station that was the U.S.'s predecessor to the International Space Station. It also marked the end of a tense standoff.

About a month earlier, the three-strong crew of Skylab 4, tired of the demanding schedule NASA had set for them, had announced an unscheduled day off, turned off their communication radio to mission control, and “reportedly spent the day relaxing, taking in the stunning views of the Earth from orbit,” writes Amy Shira Teitel for Motherboard.

After that day of silence, they reached a compromise with the ground crew, she writes. A reduced workload and the freedom to complete tasks on their own schedule was what they got, while NASA got the reward of watching the final Skylab mission finish on schedule.

The three Skylab missions (Skylab 1 was the launch of the space station itself), which took place in 1973-74, were a project that journalist David Hitt called “homesteading space.” Their purpose was to actually try living in space, as astronauts today do on the International Space Station, rather than simply making short trips.

As part of this mission, the Skylab 4 astronauts experimented with ways to overcome some of the problems associated with living in space, wrote the BBC, trying out new diets and exercises to prevent muscle loss and other symptoms of prolonged weightlessness.

The three astronauts—Gerald Carr, William Pogue and Edward Gibson—faced a demanding, lengthy mission, Teitel writes. NASA’s plan called for a total of 6,051 work hours between the three men, she writes. Basically a 24-hour schedule. Besides the medical and scientific experiments, there was loading and unloading gear and making observations of the Sun and Earth as well as the comet Kohoutek. On top of all that there were four spacewalks, at a combined total of about a day in length.

This demanding schedule was too much for the crew, she writes, which presumably led to them declaring a day off. After all, what was NASA going to do, come and get them? The one consequence of their actions we know for sure, though: none of the three ever left Earth again.

At a 2016 university award ceremony, Edward Gibson talked about his spacewalk. “When you’re out there, it’s a silent world, except for the whispers of your own breath,” he said. “It feels like the world down there doesn’t even know you’re there.”

Although the episode has been commonly called a “mutiny,” it wasn’t in the technical sense and it did have the consequence of forcing NASA to reconsider how they had been treating crews, writes Michael Hitzik for the Los Angeles Times. “NASA treated the crew as expendable instruments of its schedule, but Skylab 4 showed that when push came to shove the astronauts had all the control in their own hands.”

The astronauts’ journey back to Earth’s atmosphere took five hours, wrote the BBC. In spite of problems with the landing craft, they came down in the Pacific Ocean as planned. Gibson came out of the capsule, BBC wrote, saying, “I feel great.”