The InSight robot reveals a new map of the interior of Mars: its core is surrounded by a layer of molten rock

2023-10-25 18:59:21

Updated Wednesday, October 25, 2023 – 18:59

They discover that its liquid core, composed mainly of iron, is surrounded by a soft mantle of molten rock about 150 km in diameter

Measurements and analyzes carried out in 2021 by NASA’s retired InSight robot have offered scientists a new map of the internal structure of Mars. According to two investigations published this Wednesday in the journal Nature, the new data offer a new interpretation of the interior of the red planet, suggesting that its core is smaller and denser than previously thought.

Specifically, scientists say that Mars’ liquid iron core is probably surrounded by a complete layer of molten silicates (rocks).

Last April, another investigation conducted with InSight data revealed that The Martian heart is totally liquid, unlike that of Earth, which combines a liquid outer core and a solid inner core. Furthermore, they found out that the Martian core is not composed only or practically only of iron, but also contains sulfur and oxygen, which are light elements, in addition to carbon and hydrogen.

However, these results would indicate that the core has a higher proportion of lighter elements than is feasible, based on estimates that had been made of the abundance of these elements in the early stages of Mars’ formation history.

Teams led by Amir Khan and Henri Samuel, respectively, examined the latest batch of seismic signals and combined them with geophysical model simulations to obtain estimates of the size and composition of the Martian core. Both studies determined that The liquid iron core of Mars is surrounded by a layer of almost molten silicate rock that would be approximately 150 kilometers thick, the upper part of which had previously been erroneously interpreted as the surface of the core.

And what does this mean? This decrease in core radius would imply a higher density than estimated in the previous InSight robot study. According to the scientists, these estimates fit more easily with existing knowledge about chemical abundance on Mars, since they require fewer light alloying elements to produce a stable liquid core.

Previously, the diameter of the core was estimated to be about 1,800 km, while it is now believed to be between 1,650 and 1,675 km.

Artistic recreation of the robot and its structure beneath the surfaceIPGP/Nicolas Sarter

In an article accompanying both investigations in the same journal, Nature, scientist Suzan van der Lee, from the Department of Planetary Sciences at Northwestern University, describes these results as “the closest and most precise estimates yet obtained of the mantle and core of Mars. These findings, he adds, “show that by combining seismological observations with knowledge about the formation and evolution of terrestrial planets and data on the size, shape, rotation and magnetic field of the planet, valuable information can be obtained about the past and present of Mars, and its future dynamics”.

Unlike other robots that have explored Mars, such as Curiosity or Perseverance, InSight remained anchored to the surface. It arrived on Mars in 2018 and in 2019 it began to take the pulse of this planet, with its radars and other instruments, which have allowed Martian earthquakes, called marsquakes, to be recorded for the first time, of which it detected more than a thousand. With his SEIS instrument (Seismic Experiment for Interior Structure) he recorded the seismic waves that pass through the interior of the planet, something that has only been possible to do on Earth and the Moon.

Due to the large accumulation of dust, its solar panels stopped supplying power and the probe stopped operating at the end of 2022.