Seen from Earth, the Moon appears so bright and peaceful. But if you look closer, the lunar surface is marked by wrinkles that are also active faults, whose appearance and behavior may be more unexpected than scientists thought. In a study published yesterday in The Planetary Science Journal, scientists report the identification of more than 10,000 young faults on the lunar surface. The team referenced images from NASA’s Lunar Reconnaissance Orbiter Camera (LROC), specifically its images of ridges and long, curved structures called lobate scarps. These features are formed as a result of the contraction of a celestial body, in this case the Moon. From the analysis, the researchers concluded that the moon’s radius has shrunk by approximately 148 feet (45 meters) over the past 400 million years. Global map of the moon centered on the near side. The red lines show the location of over 8,900 lobate scarps and the blue lines show the location of over 2,000 small mare ridges. Credit: NASA/ASU/Intuitive Machines/Smithsonian This type of change is not unique to the Moon; Mercury is also experiencing a similar contraction. But the lunar surface is like a singular, intact layer, meaning moonquakes or new faults can emerge anytime, anywhere, according to a statement from the Smithsonian National Air and Space Museum, where study author Tom Watters serves as senior scientist emeritus. Shrinking and Shaking Scientists generally believe that the Moon had a violent birth; The details vary, but the gist is that something, or even a particularly large object, crashed into Earth billions of years ago, and our planet spewed hot debris into space, which coalesced into the Moon. That is why it was not news to scientists that the Moon was shrinking. According to a NASA explainer (who consulted Watters), “[m]All things shrink as they cool, and the moon is no exception.” Lobate scarps in a permanently shadowed region inside the Mouchez L impact crater near the moon’s north pole. Credit: NASA/KARI/ASU/Intuitive Machines/Smithsonian In 2019, Watters and his colleagues found evidence that these “wrinkles” on the lunar surface were actually active faults that continue to cause lunar earthquakes. According to a statement NASA at the time, the moonquakes recorded by seismometers deployed by the Apollo missions occurred close enough to the faults to establish a connection. A cloud of possible locations (magenta dots and light blue polygon) of the strong shallow moonquakes The blue boxes show the locations of the proposed landing regions for Artemis III. Credit: NASA/LROC/ASU/Smithsonian Institution This understandably raised concerns for NASA’s Artemis planning team. That didn’t go unnoticed by Watters, the resident expert on lunar earthquakes. And a 2024 study confirmed that these young faults were indeed of great relevance. Thirteen proposed landing sites for Artemis 3 (now Artemis 4) were uncomfortably close to candidates for earthquake epicenters, which could increase the risk of landslides and the like for lunar missions, according to a NASA statement on the 2024 study. A big, beautiful chunk of rock. On the other hand, it’s not like we’ve discovered a way to reliably predict earthquakes from the ground we’re literally standing on; so how would it be easier to do that for the Moon? That’s a good point, but there’s actually another, perhaps less obvious, reason why lunar earthquake predictions are more difficult. Tectonic and seismic activity is concentrated near these regions. The Moon, on the other hand, only has one large plate that “acts like an intact shell,” the Smithsonian explained, meaning that “moonquakes due to slip events on existing faults or the formation of new faults can occur anywhere on the Moon. In the paper, the team added that the insulating effect of a thick regolith in the Moon’s early days could have prevented the moon from cooling and shrinking.” “The number of these young faults revealed in the LROC images is much larger than ever before. envisioned,” Watters said in the statement. “As the Moon’s interior continues to cool and contract, the growth of existing faults and the formation of new faults are expected to continue today.” That said, it’s definitely not the end for missions like Artemis 3. The new study found that regions with a thicker lunar crust tended to have fewer faults, so these areas could be more stable than others. The longer we understand everything we can about our fate, the safer we will be, and, Actually, that’s good travel advice, even if you’re not headed to the Moon.
