Our Shrinking Moon: What It Means for Future Lunar Exploration

A region of the moon that's at the center of a new international space race because it may contain water ice could be less hospitable than once thought, new research has found.

Interest in the lunar south pole spiked last year, when India's Chandrayaan-3 mission made the first successful soft landing in the area, just days after Russia's Luna-25 spacecraft crashed en route to attempt the same feat. NASA has selected the region as the landing site for its Artemis III mission, which could mark the return of astronauts to the moon as soon as 2026, and China also has plans to create future habitats there.

But now a study funded by NASA is ringing an alarm bell: As the moon's core gradually cools and shrinks, its surface develops creases — like a grape shriveling into a raisin — that create “moonquakes” that can last for hours, as well as landslides. Much like the rest of the natural satellite's surface, the area of the south pole that is the subject of so much interest is prone to these seismic phenomena, potentially posing a threat to future human settlers and equipment.

“This is not to alarm anyone and certainly not to discourage exploration of that part of the south pole of the moon,” 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, “but to raise the caution that the moon is not this benign place where nothing is happening.”

The findings, published in the journal Nature Geoscience, are based on data from NASA's Lunar Reconnaissance Orbiter (LRO), which has been mapping the moon since 2009. The LRO has detected dozens of faults and scarps on the lunar surface, some of which are hundreds of miles long and tens of feet deep.

These features are thought to be caused by the moon's shrinking core, which is putting stress on its outer shell. As the core cools, it loses heat and contracts, causing the shell to crack and buckle.

The moonquakes that occur along these faults can be quite powerful, even though they are much weaker than earthquakes on Earth. In 2019, the LRO detected a moonquake that lasted for over 13 hours, the longest ever recorded.

The moonquakes and landslides could pose a significant challenge for future lunar settlements. The faults could break buildings and infrastructure, and the landslides could bury them. The moonquakes could also trigger avalanches of dust and rocks, which could be harmful to human health.

The new research does not mean that it is impossible to build settlements on the moon. However, it does mean that we need to be more careful about where we build them and how we design them. We need to choose

sites that are less likely to be affected by moonquakes and landslides, and we need to build structures that can withstand these events.

The challenges posed by the moon's shrinking core are just one of the many factors that we need to consider as we plan for future lunar exploration. But by understanding these challenges, we can better prepare for them and ensure that our missions to the moon are safe and successful.