The Shrinking of the Moon Is Making It Harder to Find Artemis Landing Site

While invisible to backyard astronomers, the continuing shriveling of the moon is presenting a challenge to planners of the first crewed lunar mission in a half-century.

As its core gradually cooled over the past several hundred million years, the moon has lost 150 feet in circumference, leading to fault formation and seismic activities like moonquakes and landslides in its south polar region—including areas that NASA proposed for its Artemis III landings in 2026.

A research team including a University of Maryland geologist has linked a group of faults in that region to one of the most powerful moonquakes recorded by Apollo seismometers over 50 years ago. Using models to simulate the stability of surface slopes in the region, the team found that some areas were particularly vulnerable to landslides from seismic shaking. Its study was published Thursday in the Planetary Science Journal.

“Our modeling suggests that shallow moonquakes capable of producing strong ground shaking in the south polar region are possible from slip events on existing faults or the formation of new thrust faults,” said the study’s lead author, Thomas R. Watters, a senior scientist emeritus in the National Air and Space Museum’s Center for Earth and Planetary Studies. “The global distribution of young thrust faults, their potential to be active and the potential to form new thrust faults from ongoing global contraction should be considered when planning the location and stability of permanent outposts on the moon.”

[The Moon Is Shrinking, and It’s Setting Off Moonquakes]

Shallow moonquakes occur near the moon’s surface, just a hundred or so miles deep into the crust. Like earthquakes, shallow moonquakes are caused by faults in the moon’s interior and can be strong enough to damage buildings, equipment and other human-made structures. But unlike earthquakes, which tend to last only a few seconds or minutes, shallow moonquakes can last for hours—like the magnitude 5 moonquake recorded by the Apollo Passive Seismic Network in the 1970s, which the research team connected to a group of faults detected by the Lunar Reconnaissance Orbiter more recently.

According to Nicholas Schmerr, a co-author of the paper and a UMD associate professor of geology, this means that shallow moonquakes can devastate hypothetical human settlements on the moon.

“You can think of the moon’s surface as being dry, grounded gravel and dust. Over billions of years, the surface has been hit by asteroids and comets, with the resulting angular fragments constantly getting ejected from the impacts,” he said. “As a result, the reworked surface material can be micron-sized to boulder-sized, but all very loosely consolidated. Loose sediments make it very possible for shaking and landslides to occur.”

The researchers continue to map out the moon and its seismic activity, hoping to identify more locations that may be dangerous for human exploration. NASA’s Artemis missions, which are set to launch their first crewed flight late this year, ultimately seek to establish a long-term presence on the moon and eventually learn to live and work on another world through moon-based observatories, outposts and settlements.

“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,” Schmerr said. “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.”