The internal structure of the planet Mars has finally been identified thanks to NASA’s InSight lander, which shows the size of the core, mantle and crust for the first time in history.
Since InSight arrived on Mars in late 2018, it has detected more than 1,000 tremors. Many of them originated in a seismically active region more than 1,000 kilometers from the lander. A small fraction of the earthquakes had magnitudes ranging from 3.0 to 4.0, and the resulting vibrations have allowed scientists to probe Mars and reveal new clues about its internal structure.
Using data on the ‘marsquakes’ (or marsquakes) experienced by NASA’s robot (something that can be done by measuring changes in the velocity of seismic waves as they pass from one layer to another), the researchers were able to find evidence of three layers of crust that extended more than 40 miles below the surface. Each layer of the crust has a slightly different composition, and just below the crust is the mantle, which goes down to 600 kilometers deep; the rest is an iron and nickel core.
Thus, the diagnosis of the crust is clear: the core of the red planet is at least partially liquid, as previously suggested by previous studies. Of course, it is something bigger than expected.
According to current data, we can consider two models of Martian crust: either that the crust is thin and made of two layers, a porous upper layer that could be chemically altered and a deeper layer closer to the original composition, or it could be a three-layer stage. In the first scenario, the crust below InSight would be much thinner, around 20 kilometers, and in the second, it would almost double this number.
Taking an average over the entire planet, they calculate that the crust is probably between 24 and 72 km thick. Either way, it is still much thinner than expected and suggests that the crust is rich in radioactive elements.
The mantle would be much deeper than that of the Earth, since it could extend up to 600 km , which would fit but it fits with the model of Mars that presents a large continental plate.
Further down we would find the nucleus which, unlike that of the Earth, is practically liquid . The team estimates that the core of Mars has a radius of about 1,830 km, making it about half the size of Earth, but still about 200 km larger than previously thought. Because it is so much larger, it is less dense and is now believed to contain a higher proportion of lighter elements such as sulfur, oxygen, carbon, and hydrogen.
“This work provides the first direct measurements of the inner layers of another planet. These data are key to determine its internal structure, as well as its geological and geochemical evolution,” explains Martin Schimmel, co-author of one of the works.
This information could help us discover how Mars gained and lost its magnetic field , information that could, in turn, help us better understand those of other planets including our own.
The findings were published in three independent studies (which focused on the planet’s crust, mantle, and core, respectively) that used data from NASA InSight, the University of Cologne, the California Institute of Technology, and ETH Zurich. .
Referencia: B. Knapmeyer-Endrun at University of Cologne in Bergisch Gladbach, Germany el al., “Thickness and structure of the martian crust from InSight seismic data,” Science (2021). science.sciencemag.org/cgi/doi … 1126/science.abf8966
S.C. Stähler el al., “Seismic detection of the Martian core,” Science (2021). science.sciencemag.org/cgi/doi … 1126/science.abi7730
A. Khan el al., “Upper mantle structure of Mars from InSight seismic data,” Science (2021). science.sciencemag.org/cgi/doi … 1126/science.abf2966
S. Cottaar el al., “The interior of Mars is revealed,” Science (2021). science.sciencemag.org/cgi/doi … 1126/science.abj8914
