We have spent years measuring earthquakes on Mars to realize something: its core is not like ours

For four and a half years, the InSight probe (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) from NASA measured, from its surface, the seismic activity of Mars. Thanks to the data provided by this probe, a team of researchers has managed to outline a geological model that shows us what the core of the red planet is like.

A cast iron core. New calculations on Martian geology have shown us a somewhat different core of the planet than what experts expected. The nucleus would be denser and smaller, with a radius of between 1,780 and 1,810 kilometers. It would also be composed of cast iron and a combination of other elements, among which sulfur would stand out.

“instead of being just an iron ball [el núcleo] it also contains a large amount of sulfur, as well as other elements, including a small amount of hydrogen.” explained in a press release Jessica Irving, a member of the research team responsible for the find. Elements detected in trace amounts by the team also include oxygen and carbon.

This implies that the core of our neighboring planet does not have a structure like our own interior. If the core of Mars is completely liquid, ours has two parts, a liquid exterior and a solid interior. This internal structure of the terrestrial core was only discovered a few months ago, and it is that the task of understanding what is there thousands of kilometers inside a planet is an extremely difficult task. Even on our own.

The enigma of the magnetic field. Although the task is complicated, it is important. Unlike our planet, Mars does not have a magnetic field. In our case we know that it is linked to the existing metal inside our planet.

Although we know that Mars does not have a magnetic field, experts believe it is quite probable that it had one at the time thanks to some traces left by it on the planet’s surface.

This magnetic field has been decisive for evolution of life on our planet. Understanding how, why and when it disappeared from Mars would open the way for us to understand how habitable our neighboring planet could have been in the past, when and why it stopped being so.

Two key events. The investigation is mainly based on two geological events that occurred on Mars, both of which occurred in the opposite hemisphere to the location of the InSight probe. It is about a Martian earthquake and the impact of a meteorite against the surface of the red planet.

The probe managed to capture the seismic waves generated by the two events. To reach the probe, these waves had to pass through the core of the planet. This is what researchers have used to create this new model of the interior of Mars, a methodology very similar to the one that, for more than a century, has served geologists to draw the interior structure of our own planet.

“We have been listening to the energy that travels through the heart of another planet, and now we have heard it,” said Irving, who leads the signatories of the article published in the magazine Proceedings of the National Academy of Sciences (PNAS) in which the work is reported. Signatories among whom the CSIC Geosciences Barcelona research center is also represented.

A mission squeezed to the fullest. This investigation had a certain dose of luck when it came to capturing the two great events that it took advantage of. The mission was scheduled to work for two years (which would be approximately equivalent to a Martian year), but the conditions of the probe allowed the mission to be extended until the end of last year.

All this despite the fact that the accumulation of Martian dust considerably complicated its task by hindering the arrival of sunlight to its panels. This research would not have been possible without the mission extension, which can serve as a valuable reminder that even the oldest clunkers can deliver great discoveries.

In Xataka | “We are destroying information stored there for 4,000 million years”: the problem of geologists, magnets and meteorites

Image | NASA/JPL-Caltech/University of Maryland