NASA probe insight: inner structure of Mars revealed

Thanks to the data from NASA’s InSight probe, researchers have succeeded in measuring the interior of Mars and correcting some previous assumptions. A thick mantle of solid rock and finally a liquid core follows a thin Martian crust. It’s bigger than expected, the team explains in several articles in the US journal Science.

Mars is therefore only the second planet whose internal structure is known; While the measurement of the earth’s interior took centuries, it only took two years on the red planet. In the case of the moon, it took 40 years after the Apollo missions.

Since the inner structure of the earth was understood, similar structures have been assumed in comparable rock planets such as Mars, explains the team around lead author Simon Stähler from ETH Zurich. The seismic data collected by InSight have now largely confirmed the theories, but at the same time also showed such strong deviations that further research is necessary. The Martian crust is between 15 and 47 kilometers thick, may consist of several layers and must “contain a relatively high proportion of radioactive elements”. However, that would call into question existing models of composition. The Martian mantle, which is between 400 and 600 kilometers thick, fits in well with the predictions.

Unlike that of the earth, the Martian core is liquid, the measurements would have confirmed. According to this, he has a radius of 1840 kilometers, 200 kilometers more than assumed when the mission was planned. The density of the core must therefore be lower than expected, so in addition to iron and nickel it should also contain a large proportion of lighter elements. Accordingly, sulfur, oxygen, carbon and hydrogen are possible, but their proportions would then be unexpectedly large. This suggests that the composition of the entire Red Planet is not yet fully understood. Mars still holds a lot of puzzles, but the evaluation of the collected data is not over yet.

Insight landed on Mars in late November 2018 and has been on the Elysium Planitia plain since then. The probe uses a sensitive seismometer to measure waves that occur below the surface during quakes. From their echoes in particular, they can then infer the structures on which they were reflected. Unlike on Earth, marsquakes are not triggered by plate tectonics, because they do not exist on the Red Planet. Instead, the earthquakes arise in the crust of the “One-Plate-Planet” through loads on the rock, triggered by the slow shrinking of the cooling planet. While InSights solar collectors are more and more enveloped in dust and the mission is slowly drawing to a close, the researchers are still hoping to be able to measure a really strong quake beforehand.


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