Earthquake on the Moon: Researchers discover a surprising cause

There are regular earthquakes on the moon, as NASA’s Apollo 17 mission data shows. The origin of some of these earthquakes is surprising.

PASADENA — Every afternoon, the Earth shakes on the moon. Small moonquakes are as reliable as clockwork because they are affected by conditions on the moon’s surface. The Earth’s satellite has no atmosphere, which is why temperatures there fluctuate greatly. At midday, in sunlight, temperatures reach 130°C, and at night in the dark, temperatures reach -160°C. These extreme temperature fluctuations cause small thermal lunar earthquakes: when it is hot, the Moon’s surface expands and when it is cold, it contracts.

In 1976, the crew of NASA’s Apollo 17 lunar mission installed three seismometers on the Moon that were capable of measuring these lunar quakes, and they did so from October 1976 to May 1977. A research team led by Francesco Civellini of the California University of Technology ( Caltech has now analyzed this data using new methods and been able to show that moonquakes occur with amazing precision. Every afternoon, as the Sun leaves its zenith and the Moon’s surface begins to cool, the Earth shakes.

A new study shows: The moon’s soil vibrates regularly like clockwork

However, during the analyses, the research team was able to identify a second type of moonquake that occurs at a different time of day: earthquakes that are not thermal moonquakes appear to occur in the morning. The research group discovered something surprising: the second type of lunar earthquake is not of natural origin, but comes from the lander with which the astronauts landed on the Moon and which remained in parts on the surface – very close to the seismometers.

“Every lunar morning, as the sun hits the lander, it begins to crack,” study co-author Allen Husker explains in a statement. notice. “Another one every five to six minutes, over the course of five to seven Earth hours. “It was incredibly regular and frequent.” The new study was In the specialized magazine Journal of Geophysical Research – Planets published.

What happens on the moon?

It is important for research to understand what is happening on the Moon, because people are expected to land on Earth’s satellite again in the coming years. There are also plans to establish research stations on the Moon in the medium term. Although thermal lunaquakes are too weak for humans to feel, they provide researchers with valuable information for future missions to the Moon — for example, how a lunar module should be built so it can survive the challenging temperature conditions on the Moon. .

Lunar quakes also allow researchers to get a deeper look at the soil of Earth’s satellite. If seismic waves move through different materials, scientists can analyze them – which is how geologists also look into the Earth’s interior. “We hope to be able to map underground craters and look for deposits,” Husker explains.

Lunar quakes are said to help scientists search for water ice

The researcher continues: “There are also certain areas in the craters at the south pole of the moon that never see sunlight; They are constantly in the shadows. If we could put a few seismometers in there, we could look for water ice that might be trapped underground; Seismic waves travel more slowly through water.