Watch Astronauts Falling Over on the Moon—it's for Science, Honest

You’ve been hurtling through space for three days. You land on the Moon—tired, dizzy and probably at least a little nauseous—and scramble to fasten your helmet. You open a hatch and explore an alien landscape barely touched by humans. And then you fall over.

That’s the experience of some of our nation’s moonwalkers, as the footage below sourced from NASA’s archives reveals.

Gravity—the invisible force keeping us all, for the most part, firmly on the ground—is much lower on the Moon than on our planet, about 17 percent of that felt on Earth. Although this lets astronauts bounce across the surface like they’re on a trampoline, it can also make it harder to keep their balance.

Add a chunky 80-pound spacesuit to the mix and you've got a recipe for tumbling.

Understanding the way the human body adjusts to alien terrain is a key concern for space agencies like NASA. It’s so important, in fact, that NASA kept a record of astronauts falling to the ground for both the Apollo 15 and Apollo 16 missions to the Moon.

Scientists used Apollo 15’s "Time and Motion Study" to “evaluate the differences, correlation and relative consistency between ground-based and lunar surface task dexterity and locomotion performance.” In other words, to log how and why astronauts fell over—or nearly fell—on the surface of the Moon.

It notes how astronaut David Scott loses his footing and tumbles to the ground on two separate occasions while taking photographs. The report blames gravitational effects, limited visibility and surface conditions for the falls.

7_9_Astronaut Moon Astronaut Buzz Aldrin poses for a picture on the moon, 20 July 1969. NASA

Buzz Aldrin, who was the second person to step on the Moon, roughly eight minutes after Apollo 11 commander Neil Armstrong, described the dusty surface of the orb as a little like “moist talcum powder” in a 2014 Reddit Ask Me Anything session.

The Apollo 16 Time and Motion Study devotes eight pages to six lunar falls caught on tape by NASA’s cameras. Most of the time astronauts slipped and tumbled when they bent down to pick up object bags, brushes and hammers. The uneven, dusty surface made it difficult for their feet to gain traction and they fell to the ground.

Read more: When will the U.S. next see a lunar eclipse?

This kind of information is crucial for understanding how to maximize movements in unfamiliar environments. As human space exploration points back towards the Moon and even to Mars, keeping both feet on the ground will once again be a priority for NASA.