The Moon Is Secretly Shrinking—Right Where We're Trying to Land

moon and earth moon with craters in deep black space moonwalk earth at night elements of this image furnished by nasa
The Moon Is Shrinking Where We're Trying to Landdima_zel - Getty Images
  • Scientists know that the Moon is shrinking (albeit very slowly), and this lunar down-sizing could have a seismic impact on future Artemis Moon missions.

  • A new study funded by NASA concludes that the lunar south pole is particularly rife with seismic activity, and contains “trust faults” caused by a shrinking Moon.

  • This study, along with future research, will help NASA nail the best spot to set up shop on the lunar surface.

Think you’re safe from a natural disaster on the Moon? Well, think again.

A new NASA-funded study published in The Planetary Science Journal late last month could shake up NASA’s plans (as well as China’s, Russia’s, and India’s) to explore the lunar south pole—both literally and figuratively. The study claims that the Moon is shrinking, and that this change in size is causing some intense rumbling beneath the Moon’s regolith.

“The lunar south pole regions are subjected to global stresses that result in contractional deformation and associated seismicity,” the paper reads. “The potential of strong seismic events from active thrust faults should be considered when preparing and locating permanent outposts and pose a possible hazard to future robotic and human exploration of the south polar region.”

The fact that the Moon is shrinking isn’t new—scientists have known about it since at least 2010. But as is often the case with geologic phenomena (on Earth or otherwise), the Moon’s thermal-induced downsizing has only shaved off some 150 feet over the last several hundred million years. NASA describes this Moon shrinking as a grape slowly transforming into a more diminutive raisin, but because the Moon’s crust (or “skin,” for this analogy) isn’t as flexible as a grape, it tends to form cracks known as “thrust faults,” where one section of crust overlaps another.

NASA astronauts set up seismometers on the lunar surface during the Apollo years, and from 1969 to 1977, these instruments recorded upwards of 28 shallow moonquakes—eight of which could be attributed to these faults. Although none of these earthquakes cracked 5.0 on the Richter scale, moonquakes would feel worse due to lower lunar gravity.

This new paper adds more details of the Moon’s seismic hellscape. For example, these moonquakes can last for hours, can cause landslides, and could be a big problem for anyone hoping to set up shop in the lunar south pole.

The study’s lead author Thomas R. Watters and his team used data collected from the Lunar Reconnaissance Orbiter—launched back in 2009—to more closely study (among other things) that original Apollo data.

“We knew from the Apollo seismic experiment… that there were these shallow moonquakes, but we didn’t really know what the source was,” Watters told CNN. “We also knew that the largest of the shallow moonquakes detected by the Apollo seismometers was located near the south pole. It kind of became a sort of a detective story to try to figure out what the source was, and it turns out that these young faults are the best suspect.”

Watters’ modeling suggests that the lunar south pole is susceptible to these quakes and landslides, and even includes a thrust fault in the Gerlache Rim 2, which is an Artemis III landing zone candidate. These geologic shake-ups even occur in permanently shadowed regions, which is particularly important, as it’s believed that these areas could contain water in the form of ice—an important resource for any future lunar settlement.

Hey, no one said lunar life was going to be easy.

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