On December 24, 2021, something strange happened on the surface of Mars. now we know what it was

In 2021, NASA’s InSight had been recording earthquakes on the red planet for three years. However, that night of December 24, the seismograph recorded something never seen. Something that aroused the curiosity of the researchers and made them suspect that something strange had happened. What could those strange seismic waves be?

The first meteorite we captured on Mars. Immediately, the InSight team began to analyze seismograph history. Thus they found that a few months earlier, on September 18, 2021, a similar (although smaller) wave had been recorded. However, the key to understanding what was happening to those strange seismic waves did not come from InSight, but from higher up.

Crossing the data with that of the Mars Reconnaissance Orbiter (MRO) probe, it was found that there was an impressive crater 150 meters in diameter where before that December 24 there was nothing. It was surprising: that meant that the waves had traveled 3,500 kilometers in the first case (7,500 kilometers in the second). It was the first time we had detected such an impact on the surface, but it was something else.

What we didn’t know about the bark…. Because by analyzing the waves, researchers they realized that key data could be extracted about the interior of the planet, about the structure of its crust and what lies up to 30 kilometers below its surface. After all, as Doyeon Kim, a geophysicist at the Federal Polytechnic School in Zurich, put it, “until now our knowledge of the Martian crust has been based on the measurement of a single point under the lander.” And with these data, we could not imagine that the planet had “such a uniform structure and such a high density.”

…and also about the atmosphere. Furthermore, MRO has never identified newly formed craters on the planet’s surface and has been circling the planet for 16 years. By doing so (and being able to cross them with those of the seismograph) we not only learn things about the crust, but also about the atmosphere. Because, whether we like it or not, the nature of the Martian atmosphere (as it also happens on Earth) is decisive in these impacts.

Why is all this important? Fundamentally because of the “Martian dichotomy”. Just look at the topographic map above to check the huge differences between the northern hemisphere and the southern hemisphere of the planet. While in 60% of the surface we can find many craters, in 40% there are almost none.

Although the researchers relate all this to a huge impact and a huge eruption that covered the planet with lava, the planetological consensus believed that the crust of Mars had to be different in both zones. Now, thanks to this discovery, we know that it is not. Where does this lead us? It is not clear, but it will have very interesting consequences for the future colonization of our neighboring planet.