The seismic robot InSight has been on the Martian surface since 2018, observing the chills and tremors of the planet, called earthquakes, which can reveal the inner state of our cosmic neighbor. In the past two years, more than five hundred have passed under his proverbial feet.
By closely following these earthquakes, researchers were able to reconstruct the interior of the planet. The speed and direction of these seismic waves depend on the material through which they travel. Previously, this type of data was only available on the Earth and the Moon.
Large liquid core
After analyzing the waves, three international research teams “See” structures up to 800 kilometers below the surface. In addition, measurement data revealed that the crust of Mars with a thickness of 24 to 72 kilometers thicker than that of the Earth, which measures only 7 kilometers under the oceans. The crust also consists of two or three layers.
Inside the planet is lapping as expected a liquid core, which, with a diameter of 1,830 kilometers, turns out to be slightly larger than expected. The outer edge of this liquid sphere even extends halfway between the surface and the center of the planet.
It was also discovered that below its surface Mars has only one subterranean rock layer, 500 kilometers thick, while Earth has two. The core, which like that of the earth is made up mostly of iron and nickel, also has a somewhat lower density than previously thought.
Together, the results should help reconstruct the birth of Mars billions of years ago. In the years to come, InSight will record even more earthquakes, refining the view of the interior of the planet. In this way, the researchers also hope to find out what has happened inside over the past billions of years.
The biggest volcano
Mars still has some great mysteries, such as why the planet has the largest volcano in the solar system (Olympus Mons, now extinct), while it has little or no volcanism compared to to Earth today. By revealing in detail the interior of the two planets, one can find out where the differences are coming from.
Another open question is where has Mars’ magnetic field gone? On Earth, the oscillating core serves as a sort of dynamo that generates the field, but on Mars, such a field is practically absent. A possible explanation – that the once liquid core has now solidified – can already be ruled out with the new measurement data.
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