The seismometer of a NASA Martian robot has made it possible to find out what the interior of the red planet is like, directly measuring the properties of its core: its heart is totally liquid – unlike that of Earth, which combines a liquid outer core and a solid inner core. In addition, to the surprise of scientists, the Martian core is not composed only or practically only of iron, but has high percentages of sulfur and oxygen, which are light elements. They have also found small amounts of carbon and hydrogen.

These are the main conclusions drawn thanks to the data collected by the InSight probe, which arrived at Mars in 2018 and was operational until the end of last year, when the accumulation of Martian dust made it impossible for its mission to be expanded again. InSight became famous studying the marshmallows, that is, the seismic movements that also shake this planet of the Solar System with so many things in common with ours.

Fortunately, the mission of the robot, which in principle was going to last just over a Martian year (two Earth years) could be extended, because it was in that period of extension when the two geological events occurred, distant from each other, that generated those seismic waves that have allowed us to know what the interior of the planet is like: one was martemoto (a Martian earthquake) and the other, The fall of a meteorite.

"Two seismic signals, one from a very distant martemot and another from a meteorite falling on the other side of the planet, have allowed us to probe the Martian core with seismic waves. Sure enough, we have been listening to the energy that travels through the heart of another planet, and now we have heard it, "summarizes Jessica Irving, the researcher at the University of Bristol who leads this study published today in the journal Proceedings of the National Academy of Sciences (PNAS).

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Geology.

The InSight robot reveals the intimacies of Mars: this is what its earthquakes and its heart are like

  • Writing: TERESA GUERRERO Madrid

The InSight robot reveals the intimacies of Mars: this is what its earthquakes and its heart are like

Those two events generated seismic waves on the opposite side of the robot's side. By comparing how long it took those generated seismic probes to travel through Mars compared to how long it took for the waves that remained in the mantle, and by combining this information with other seismic and geophysical measurements, scientists

COS estimated the density and type of material through which the waves traveled. The results indicated that Mars most likely has a completely liquid core, unlike Earth's combination of a liquid outer core and a solid inner core.

As Vedran Lekic, co-author of this paper, recalls, the Earth's core was discovered in 1906, when scientists observed how seismic waves from earthquakes were affected by traveling through it: "More than a hundred years later, we are applying our knowledge of seismic waves to Mars. With InSight, we're finally figuring out what's at the center of Mars and what makes it so similar but distinct from Earth."

Measurements of this acoustic energy, called seismic waves, indicate that its liquid core is slightly denser and smaller than previously thought, with the estimated radius being 1,780-1,810 kilometers. Its liquid composition is, as we said, a mixture of iron with sulfur and oxygen. These two light elements constitute one-fifth of the weight of the core, an amount much higher than the light elements in the Earth's core. This would mean that the Martian core is much less dense than that of our planet.

The magnetic field

"The uniqueness of Earth's core allows it to generate a magnetic field that protects us from solar winds, allowing us to conserve water. The core of Mars does not generate this protective shield, so the conditions of the planet's surface are hostile to life," summarizes Nicholas Schmerr, co-author of the article and researcher also at the University of Maryland.

InSight's seismometer, covered in Martian dust

But just because Mars doesn't have a magnetic field today, doesn't mean it hasn't had one in the past. In fact, due to the traces of magnetism in the crust of Mars, geologists hypothesize that it had a magnetic shieldor similar to the field generated by the Earth's core, so they believe that it is possible that it gradually evolved to its current conditions, going from being a world with a potentially habitable environment to a planet with incredibly hostile conditions for life as we know it on Earth. Conditions inside play a key role in this evolution, as do violent impacts, according to the researchers.

As an example of this likely Martian evolution, Professor Lekic mentions the tiny traces of hydrogen in the Martian core: "It means that certain conditions have had to be in place for that hydrogen to be there, and we have to understand those conditions if we want to understand how Mars has become the planet it is today."

Scientists have not finished analyzing the seismic data collected by InSight during its four years of work, so they hope to continue obtaining more results on the evolution of Mars that allow them to be compared with other bodies in the Solar System. In addition, the authors who signed the study published on Monday consider that the results of this NASA probe can inspire future expeditions to study the geophysical characteristics of other celestial bodies and planets such as Venus or Mercury.

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