What the new research shows – why scientists are worried

space moon At the heart of a new international space race because it may contain frozen water, it may be a less hospitable host than we thought, according to new research.

Interest in the lunar south pole increased last year when the Indian Chandrayaan 3 mission made the first successful soft landing in the region, days after the Russian Luna 25 spacecraft, which was attempting to carry out the same mission, crashed. NASA, according to CNNIt has chosen the area as a landing site for the Artemis 3 mission, which could mark the return of astronauts to the moon as early as 2026, while China also plans to create future habitats there.

However, there is now a study funded by NASA and published in Planetary Science JournalThe alarm sounds: As the moon's core gradually cools and shrinks, “cracks” develop on its surface, triggering “moonquakes” that can last for hours, as well as landslides. Like the rest of Earth's natural lunar surface, the Antarctic region that is the subject of so much attention is vulnerable to these seismic phenomena, which could pose a threat to future human settlers and their equipment.

The study's lead author, Thomas R. “This won't worry anyone and certainly won't discourage exploration of this part of the lunar south pole,” said Dr. Waters, senior scientist emeritus at the National Air Museum's Earth and Planetary Center. Studies and space, she added: “However, attention must be focused on the fact that the moon is not this benevolent place where nothing happens.”

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What is the source of moonquakes?

The Moon's circumference has shrunk by about 45 meters over the past few million years, a geologically significant number, but too small to cause any ripple effect on Earth or its tidal cycles, according to the researchers.

On the surface of the moon, the matter is different. Despite what its appearance might suggest, the Moon still has a hot interior, making it seismically active.

Thomas R. said: Waters: “There's an outer core that's molten and it's cooling. As it cools, the Moon shrinks, the interior volume changes, and the crust has to adapt to that change — it's a global contraction, which is also contributed by tidal forces on Earth.”

Because the Moon's surface is fragile, this drag creates “cracks,” which geologists call “rifts.” Notably, Thomas R. Waters: “The Moon is thought to be this geologically dead body where nothing has happened for billions of years, but that couldn't be further from the truth. These controversies are very new and things happen. In fact, we've discovered landslides that occurred during the time the spacecraft was Lunar reconnaissance in orbit around the moon.

NASA's Lunar Reconnaissance Orbiter, or LRO, was launched in 2009 and is mapping the lunar surface using various instruments. In the new study, published January 25 in The Planetary Science Journal, Thomas R. Waters and his colleagues collected data collected by the LRO probe to link a powerful lunar earthquake detected by instruments left by Apollo astronauts more than 50 years ago, with a series of faults at the lunar south pole.

Thomas R. said: “We knew from the Apollo seismic experiment, which had four seismometers running over about seven years, that these shallow moonquakes existed, but we didn't really know where they came from,” Waters said, noting: “We also knew that the largest moonquakes The shallows detected by the Apollo seismometers were near the South Pole. It became a bit of a detective story to try to figure out the source, and these tiny faults turned out to be the best suspect.

The strongest earthquake recorded was 5 on the Richter scale. On Earth, this would be considered a moderate earthquake, but the Moon's low gravity would make it appear worse, said Thomas R. “On Earth, we have a much stronger gravity that keeps us stuck to the surface,” Waters noted. On the Moon, it is much smaller, so any slight acceleration of the Earth could cause us to fall while walking. “This kind of impact can actually start throwing objects into a low-gravity environment.”

Short term vs. Long term effects

The study's results will not impact the Artemis III landing site selection process given the scope and duration of the mission, according to study co-author and NASA planetary scientist Renee Weber.

“This is because it is difficult to accurately estimate how often a particular area experiences a moonquake, and as with earthquakes on Earth, we cannot predict moonquakes,” said Rene Weber, adding: “Strong, shallow moonquakes are rare and pose a risk.” Low risk for short-duration missions to the lunar surface.”

NASA has identified 13 candidate landing sites for Artemis III near the Moon's south pole, using criteria such as the ability to land safely in the region, the ability to achieve science objectives, availability of launch conditions, terrain, communications and lighting. As part of the mission, the two astronauts will spend about a week living and working on the moon's surface.

However, as René Weber noted, for a long-term human presence on the Moon, the site selection process could already take into account geographic features, such as proximity to tectonic features and topography.

Risks of manned missions to the moon

Moonquakes could already pose a problem for future manned landing missions, said Yoshio Nakamura, professor emeritus of geophysics at the University of Texas at Austin, who was among the researchers who first looked at the data collected by seismic stations. .

However, Yoshio Nakamura, who was not involved in the study, disagrees with the cause of the earthquakes and says that the Apollo data show that the phenomena originate at a depth of tens of kilometers below the surface.

“We still don't know what causes shallow lunar earthquakes, but it's not a fault of near-surface slippage, and we need more data about it,” Yoshiya Nakamura said.

Whatever the reason behind it, the potential danger lunar quakes pose to astronauts will be limited by the fact that humans — at least for the foreseeable future — will be on the moon for short periods of time, a few days at most, according to Allen Hasker, a professor of A geophysics researcher at Caltech, who was also not involved in the study.

“It is very unlikely that a large earthquake will occur on the Moon while they are there. However, it is good to know that these seismic sources, which cause earthquakes, exist. It could be an opportunity to study the Moon better, as we do on Earth with earthquakes,” adding: “By the time there is a real base on the Moon, we should have a much better idea of ​​what a real earthquake is.” Risking upcoming missions.

This view is shared by Jeffrey Andrews Hanna, an associate professor of planetary science at the University of Arizona, who was also not involved in the work. “Lunarquakes are a wonderful tool for science,” he said, noting that they are like flashlights on the moon’s interior that illuminate its structure so we can see them. “Studying lunar quakes at the South Pole will tell us more about the Moon’s internal structure as well as its current activity.”