The moon is getting smaller, and the likelihood of future manned missions and the establishment of outposts on the surface of Earth's natural satellite is in jeopardy.
Why is the moon getting smaller – Photo Shutterstock
The Moon's interior is still hot and molten at its core, making Earth's satellite prone to seismic activity. As it cools, the Moon contracts and becomes smaller. Over the past hundreds of millions of years, the circumference of the celestial body has decreased by about 50m, partly due to the tidal forces exerted by the Earth, reports Euronews.
This cooling of the Moon leads to the appearance of “thrust faults“, on the fragile surface of the Moon, which in turn causes lunar earthquakes.
“Some of these earthquakes can be quite strong, around five on the Richter scale,” says researcher Thomas R Watters in a 2019 study published in the journal Nature Geoscience
“Monthly earthquakes” appear as the Moon grows smaller and smaller. That puts NASA's future manned mission to the moon at risk.
Previously, an area believed to have deposits of water, which could support life, had been set aside. But this region may not be as suitable for humans as previously thought because it has been affected by significant seismic activity, an effect of the Moon's shrinking size, according to a new study.
The region near the lunar south pole has become the focus of an international space race after India's historic Chandrayaan-3 lander successfully landed there in August. The purpose of the Indian mission is to locate a water source; scientists believe that ice could be found in the giant craters in the southern polar region, which is permanently in shadow.
Incidentally, NASA has selected an area in the region known as de Gerlache Rim II as a candidate landing site for its Artemis 3 mission, which is now scheduled for late 2026 at the earliest.
Earthquakes on the Moon
A study was published in the Planetary Science Journal last month showing that the area near the proposed landing site was affected by one of the strongest seismic events recorded by seismometers left behind by previous Apollo astronauts more than half a century ago after. The study used data from NASA's Lunar Reconnaissance Orbiter (LRO), which was launched in 2009 to map the surface of the Moon.
Experts warn that these “monthly earthquakes” could pose a potential threat to the personnel of future manned missions or to the inhabitants of new settlements, causing landslides or opening new faults.
“Our modeling suggests that these shallow lunar earthquakes capable of producing strong ground shaking in the South Polar region are possible following slip events on existing faults or the formation of new thrust faults.said Thomas R Watters, senior research scientist emeritus in the National Air and Space Museum's Center for Earth and Planetary Studies and lead author of the study.
Earthquakes on the moon should be considered “when planning the location and stability of permanent outposts on the Moon“, adds the author of the study.