The moon is shrinking, and future NASA flights may be profoundly affected by that new reality, a new study asserts.

As the moon’s metallic core continues to cool after it was formed roughly 4.5 billion years ago, the lunar surface — which is not supple but brittle — contracts even more, leaving it more vulnerable to earthquakes, as researchers from the University of Maryland posit. Those earthquakes could prompt landslides that would endanger astronauts on the surface.

“As we get closer to the crewed Artemis mission’s launch date, it’s important to keep our astronauts, our equipment and infrastructure as safe as possible,” Nicholas Schmerr, a geologist at the University of Maryland who helped author the study, stated. “This work is helping us prepare for what awaits us on the moon – whether that’s engineering structures that can better withstand lunar seismic activity or protecting people from really dangerous zones.”