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As NASA prepares to send astronauts to the Moon’s south polar region for the first time during the Artemis III mission, scientists are focused on an invisible but powerful challenge — moonquakes.
The Moon isn’t as silent as it seems. Its crust bears thousands of cracks, or faults, created as the lunar interior slowly cools and shrinks. When these faults shift suddenly, they unleash moonquakes. Between 1969 and 1977, seismometers placed by Apollo astronauts detected thousands of tremors, some lasting for hours — far longer than the seconds or minutes of a typical earthquake on Earth.
Although the strongest moonquakes reach only about magnitude 5.0 (weaker than Earth’s devastating magnitude 7.0 quakes), their drawn-out shaking could tip over structures, destabilize landers, and disrupt surface operations. “The hazard probability goes way up depending on how close your infrastructure is to an active fault,” explained Thomas Watters, senior scientist emeritus at the Smithsonian’s National Air & Space Museum.
To understand these risks, Watters and planetary seismologist Nicholas Schmerr of the University of Maryland developed a new technique. By analyzing evidence of dislodged boulders and landslides — scars left behind by past quakes — they can estimate quake strength and frequency. Their findings, recently published in Science Advances, could help NASA choose safer landing and building sites for future missions.
One case study centered on the Lee-Lincoln fault in the Taurus-Littrow valley, near where Apollo 17 astronauts landed in 1972. The astronauts collected boulder samples that now serve as geological timekeepers. By measuring how long the boulders’ surfaces have been exposed to cosmic radiation, scientists estimated when they tumbled downhill — likely shaken free by moonquakes.
The team concluded that a magnitude 3.0 moonquake occurs along the Lee-Lincoln fault about once every 5.6 million years. The odds of such a quake striking during Apollo 17’s stay? Roughly 1 in 20 million. Still, the evidence shows that faults like Lee-Lincoln remain active today, and could rumble again in the future.
Now, attention is turning south. NASA plans to apply this technique to faults in the lunar south polar region — the very area where Artemis III astronauts will explore. To enhance preparedness, NASA is also sending new seismometers. The upcoming Farside Seismic Suite will deploy in Schrödinger basin as part of NASA’s CLPS program, while the Lunar Environment Monitoring Station — co-led by Schmerr — may join Artemis III at the South Pole. These instruments will help map seismic hazards and guide how humanity builds a sustainable presence on the Moon.
For now, every quake-scattered boulder and landslide tells a story — not of destruction, but of the Moon’s restless heartbeat. By listening closely, scientists are ensuring that when astronauts return, they will be ready.