They solved one of the biggest mysteries of Mars

In the 70s Viking probesent by NASA to study Mars, took several images and measurements that demonstrated a very curious fact on the Red Planet. They saw that it was divided into two very clear parts. The southern part is full of craters and traces of lava flows, while the northern part is flat and smooth. In addition, the southern zone has a difference in height from the northern one by approximately 5 or 6 kilometerswith the southern region being the highest. This clear distinction between one half and the other has been called Martian dichotomy and since then its origin has remained a mystery.

There were basically two hypotheses: endogenous and exogenous. The balance did not seem to tip one way or the other. However, thanks to the module Understanding, sent to Mars by NASA in 2018, it finally had enough data to point in a direction.

This became possible thanks, on the one hand, seismograph located between the instruments of the spacecraft and, on the other hand, at its landing site, very close to the boundary separating the two halves of the Martian dichotomy.

Two hypotheses for the Martian dichotomy

The Martian dichotomy consists of more than just what has been described so far. Between the two halves of Mars, there is even more heterogeneous data. For example, the southern area’s bark is thicker and its stones have magnetism, which indicates that they belong to the time when there existed on this planet global magnetic field.

There are scientists who believe that this may have an external origin associated with the impact of a large object that suddenly changed the orography of the planet. This is an exogenous theory. On the contrary, other scientists believe that it may be due to the flow of heat occurring from the hottest to the coldest parts of the planet’s interior. They are defenders of the endogenous theory.

Understanding is the key to success

Insight’s challenge in analyzing earthquakes on the Red Planet is enormous. As explained in the article for Talk one of the researchers who analyzed their data, Hrvoje Tkalcic, Earth is full of seismographs scattered all over the planet, but on Mars everything depends on the efficiency of Insight.

A seismograph on board the lander detects S and P waves associated with ground vibrations and, by measuring the time difference between them, determines the location of earthquakes.

The P waves are the so-called primary waves, and the S waves are the secondary waves. They got this name because Ps are much faster and reach seismographs. Since we know the approximate speed of each of them and the difference between them, the time that passes between the arrival of one and the other helps to calculate the distance between the center of the earthquake and the instrument that detected it. . This applies to Earth, Mars or any planet with earthquakes.

On the other hand, by analyzing the movement of particles in the ground, we can know the direction of the earthquake.

The winning Martian dichotomy hypothesis

Thanks to this information and other data from satellite cameras, it was possible to detect earthquake group in the southern highlands, which will further study the Martian dichotomy. Subsequently, another interesting group of earthquakes was located in the northern lowland.

Once this was done, Insight mission scientists studied how S-waves lose energy as they travel through rock in every part of the planet. It was clear that the waves were losing energy much faster in the souththerefore, one can intuitively understand that the underground rock in this area is much hotter. Those responsible for the study believe that the Martian dichotomy may be the result of a combination of this temperature difference and a blocking of tectonic plate movement that occurred at some point in the Red Planet’s past. This would leave the planet divided, as if the lid of a container had been stuck in the wrong way.

In short, the endogenous Martian dichotomy hypothesis wins in this new study. All thanks to the ship that flew to Mars in 2018. It’s been many years, but at least it seems like the mystery is almost solved.