Earthquakes are detected for the 1st time on Mars – 04/26/2023 – Science

For the first time, an international team of scientists has observed a series of seismic waves passing through the core of Mars.

These observations revealed that the red planet’s core is smaller and denser than previously estimated (with a radius of approximately 1,780 km-1,810 km) — and is composed of a completely liquid iron alloy with high percentages of sulfur and oxygen.

This discovery, made from measurements by NASA’s Insight probe, the American space agency, will offer a better understanding of how the planet originated and how it differs geologically from ours.

The research results were published in the scientific journal Proceedings of the National Academy of Sciences.

TWO MAJOR SEISMIC EVENTS

In 1906, scientists discovered the Earth’s core for the first time, observing how seismic waves caused by earthquakes were affected as they passed through it.

“More than a hundred years later, we are applying our knowledge about seismic waves on Mars”, explained Vedran Lekic, associate professor of geology at the University of Maryland, in the United States, and co-author of the study.

The team was able to follow the progression of two seismic events (one caused by an earthquake, and the other by an asteroid impact), which occurred in the opposite hemisphere to which Insight is located.

By measuring the time it took them to pass through the core and comparing it with the mantle waves, and by combining that information with other seismic and geophysical measurements, the researchers were able to estimate the density and compressibility of the material passed through by the waves.

This shows that the core of Mars is likely completely liquid, unlike Earth’s core, which has a liquid outside and a solid inner core.

MAGNETIC FIELD

On the other hand, the core of Mars contains a high proportion of light elements mixed within it. About a fifth of its weight is made up of these elements (predominantly sulphur, with smaller amounts of oxygen, carbon and hydrogen).

This means that we are facing a much less dense core than Earth’s, and this difference points to different conditions in the formation of the two planets.

“The properties of the core can serve as a summary of how the planet formed and how it evolved dynamically over time,” explained Nicholas Schmerr, professor of geology at the University of Maryland, another co-author of the study.

And the end result of these processes of formation and evolution are those that may or may not give rise to conditions favorable to life.

“The uniqueness of the Earth’s core allows it to generate a magnetic field that protects us from solar winds, allowing us to conserve water,” said Schmerr.

In contrast, “the core of Mars does not generate that protective shield, without which conditions on the planet’s surface are hostile to life.”

Although this magnetic field is not present on Mars today, previous research suggests that it could have existed in the past, but it lost certain elements and evolved in such a way that it went from a planet with a potentially habitable environment to a hostile planet.

“Determining the amount of these elements in the planetary core is important for understanding the conditions in our solar system when planets were forming and how these conditions affected the planets that formed,” explained Doyeon Kim of the Federal Polytechnic School of Zurich in Switzerland. , another co-author of the study.

Studying the interior of Mars — the main objective of the Insight mission — will help researchers better understand how all rocky planets, including ours, formed.