The moon is getting smaller and smaller, and that can be dangerous for astronauts who land there: why is that?

The moon is getting smaller and smaller, and that can be dangerous for astronauts who land there: why is that?
The moon is getting smaller and smaller, and that can be dangerous for astronauts who land there: why is that?

The NASA-funded study, published in scientific journal The Planetary Science Journal, focuses on the celestial body’s south pole, a veritable new hotspot for international space organizations. Interest in this area increased significantly last year after an Indian mission made the first successful soft landing in the area. NASA also chose the region as a possible landing site for the so-called Artemis-III mission. During this mission, which will take place in 2026, astronauts will finally return to the moon. The South Pole is also in the sights of China and Russia.

On January 24, another Japanese lunar lander landed on the surface. — © via REUTERS

Alarm bells are going off

A suitable place for astronauts to stay, you would think. But the new research does set off some alarm bells. It works like this: the core of the moon cools and gradually shrinks. This causes wrinkles to appear on the surface. According to researchers, this can be seen as a grape shriveling into a raisin. The folds that form cause moonquakes. These can last hours and be accompanied by landslides. Researchers fear they may pose a threat to future human colonists.

Lead author of the study, Thomas R. Watters, says the purpose of the study is not to discourage exploration of the moon, “but to warn that the moon is not some benign place where nothing happens.”

Decreased 50 meters in circumference

To put it into perspective: the moon has decreased in circumference by ‘only’ about 50 meters over the past few million years. Over the past 4 billion years, the diameter would have become 180 meters smaller (currently 3,475 kilometers). Geologically speaking, this is significant, but it is not enough to be noticeable on Earth. Now the moon influences, among other things, the tides on Earth, but also literally on our time on Earth. According to scientific news site Scientias Without the moon, the days on Earth would be very different, namely a lot shorter. The moon slows down the earth. As a result, it needs 24 hours to complete a circle around its axis. Without the moon, however, it would spin much faster, meaning a round would only take about six hours. Without a moon, a day would be 75 percent shorter.

On Earth we may not notice the shrinking of the moon, but on the moon itself it is different. Even though the moon is cooling, the interior is still warm. According to Watters, “the outer core that has melted is also cooling.” As this happens, the moon shrinks. “This changes the volume and the crust has to adapt to that change.” This causes cracks, called fractures by geologists, because the moon’s surface is brittle. These cracks cause the moonquakes.

According to Watters, the moon has long been seen as a geologically dead object where nothing has happened for billions of years. However, we “couldn’t be further from the truth” with this assumption. The moonquakes had already been noted in previous research, but until now the cause was still a matter of guesswork.

Never go to the moon again?

The moonquakes could pose a threat to future missions, according to researchers. However, according to co-author of the study and NASA scientist Renee Weber, the results of the study will not yet have any influence on short-term missions, including the Artemis-III mission in 2026. According to research professor Allen Husker, this is due to the fact that people will be on the moon for at most a few days in the near future.

“Strong, shallow moonquakes are not common,” he says. It is therefore considered “very unlikely” that a major moonquake will occur while the Artemis-III astronauts are on the moon, as they will only be there for a short time. “By the time we build a moon base, we should really have a much better idea of ​​the real seismic hazard.”

What about the Earth? The diameter of our planet (12,700 kilometers) changes little or nothing: up to 0.1 millimeters per year, according to research in 2011.

The article is in Dutch

Tags: moon smaller smaller dangerous astronauts land