The first portrait of the heart of Mars

To discover what is hidden in the depths of the heart, one must know how to grasp every thrill, every jolt.

This is what NASA's InSight lander did on Mars, managing to map the 'heart' of the planet for the first time thanks to the study of the propagation of the seismic waves that shake it.

A sort of 'ultrasound', never attempted before on a planet other than Earth, which made it possible to estimate the

, the

and the

.

The results are the result of three international studies that conquer the cover of Science magazine, they are so important to shed light on the formation and evolution of the now super 'busy' Red Planet, with the Emirate Hope probe, the Chinese Tianwen-1 and the Mars 2020 on the hunt for life.

For InSight, which landed on Mars at the end of 2018, “it was like listening to a patient's heartbeat to understand his health conditions”, comments Filippo Giacomo Carrozzo, researcher at the Institute of Space Astrophysics and Planetology at INAF.

"It did so thanks to a very sensitive seismometer, capable of detecting subsurface tremors the size of a hydrogen atom."

Clouds move on NASA's InSight lander Seis seismometer, protected by a small dome (source: NASA / JPL-Caltech)

The NASA lander began detecting earthquakes in February 2019, "giving us the first direct confirmation of their existence: the recorded tremors all have a magnitude of less than 4 and mostly originate in the crust." Their propagation underground "offers us the

, which until now we had only been able to deduce from theoretical models".

The data shows that below the InSight landing site, near the Martian equator, the

is made up of

with at least two or three interfaces.

“Extrapolating the data on the whole planet, it can be deduced that the crust has an

”, explains Carrozzo.

Continuing towards the center of the planet, under the rocky layer of the mantle, there is the

, which has a radius of almost

, about half that of the planet.

The recording of an event that took place on Mars on July 25, 2019, recorded by NASA's InSight lander.

The track is studied to see if it was a seismic event or another type of disturbance (source: NASA / JPL-Caltech)

“The real surprise is that the

and not solid as we thought: it is less dense than expected, formed by an alloy of iron and nickel with other lighter elements and enriched with sulfur,” explains the Inaf expert. The presence of a rather thin mantle, probably devoid of the mineral bridgmanite present instead in the Earth's mantle, implies that the primordial core of Mars could have cooled faster than the Earth's: the heat emitted would thus have produced electric currents giving rise to a geodynamo that would have created a magnetic field.

According to Carrozzo, "these data, together with the magnetization of the Martian crust measured by InSight, suggest that

there may have been a

, able to act as a shield protecting any life forms from radiation and solar wind ”.