As NASA prepares to land astronauts near the Moon’s south pole for the first time with the Artemis III mission, scientists are taking a closer look at an unusual but very real hazard: moonquakes.
The Moon may look like a quiet, frozen world, but it isn’t entirely still. Over time, its interior has slowly cooled and shrunk, causing the surface to crack.
These cracks, called faults, can shift suddenly, and when they do, the Moon shakes.
Tracking moonquakes
Between 1969 and 1977, Apollo astronauts set up seismometers on the lunar surface that detected thousands of these tremors.
The strongest recorded moonquakes reach about magnitude 5.0, which is weaker than powerful earthquakes on Earth (about 7.0 or higher), but still capable of rattling the lunar landscape.
What's more, moonquakes can last for hours, as opposed to earthquakes, which last for seconds or minutes.
That long shaking, scientists say, could threaten structures like habitats, vehicles or even rocket launchers as part of permanent lunar habitats.
“The hazard probability goes way up depending on how close your infrastructure is to an active fault,” explained Thomas Watters, a lunar geologist at the Smithsonian’s National Air & Space Museum.
Reading moonquakes in the lunar landscape
Watters and his colleague Nicholas Schmerr, a planetary seismologist at the University of Maryland, published a study in Science Advances describing a new way to estimate moonquake activity.
Their technique relies not on seismometers, but on studying the Moon’s scars.
They focused on the Lee-Lincoln fault in the Taurus-Littrow valley, near the Apollo 17 landing site.
In 1972, Apollo 17 astronauts Gene Cernan and Harrison Schmitt even walked close to this fault, collecting samples of large boulders at its base.
The researchers found evidence that some of those boulders had once rolled down nearby mountainsides, likely shaken loose by past quakes.
By analysing samples from this area brought back by the Apollo 17 astronauts, they were able to deduce how long the rocks had been exposed to cosmic radiation.
Using this natural clock, they could estimate when the boulders were displaced.
Combined with measurements of their size and the distance they traveled, the team worked out how powerful the moonquakes must have been.
The results suggest that a quake of about magnitude 3.0 strikes the Lee-Lincoln fault roughly once every 5.6 million years.
That’s rare: so rare that the odds of Apollo 17 astronauts being shaken during their mission were just 1 in 20 million.
Still, the study confirms that the Moon is not geologically dead.
"Many similar faults have likely had multiple quakes spread out over millions of years," Schmerr says.
"This means that they are potentially still active today."
Preparing for Artemis
NASA is aiming to return humans to the Moon in just a few years with the Artemis III mission.
Unlike Apollo, Artemis missions will explore the lunar south pole, a region riddled with faults.
Knowing where moonquakes are most likely helps planners choose safe landing sites for astronauts and protect future lunar bases.
NASA is also preparing to bring new 'ears' to the Moon.
Later this decade, the Farside Seismic Suite will place sensitive seismometers in Schrödinger basin on the Moon, while another instrument — the Lunar Environment Monitoring Station — is being developed for Artemis III to monitor ground shaking at the south pole.
