Studies provide more insight into the internal structure of Mars 

Published - October 28, 2023 09:15 pm IST

Mars’s liquid iron core is likely to be surrounded by a fully molten silicate layer, according to a pair of studies published in Nature. These results offer a new interpretation of the interior of Mars, suggesting its core is smaller and denser than previously proposed.

Seismological study of Mars to understand the interior of the red plant was carried out in 2019. The InSight Mars Lander used an instrument called the Seismic Experiment for Interior Structure (SEIS) to record seismic waves passing through Mars’s interior. Data from three years of quakes in Mars, including two seismic events caused by meteorite impacts, were used for the study.

The analysis of measurements from the NASA InSight lander’s Seismic Experiment for Interior Structure (SEIS) project in 2021 suggested the presence of a large but low-density core, composed of liquid iron and lighter elements such as sulphur, carbon, oxygen and hydrogen. However, the result of the two studies published in Nature results suggest that the core has a higher proportion of lighter elements than is feasible according to estimates of the abundances of these elements early in Mars’s formation history.

Amir Khan from the Institute of Geochemistry and Petrology, ETH Zürich, Zurich, Switzerland and colleagues and Henri Samuel from Université Paris Cité, Institut de physique du globe de Paris, CNRS, Paris, and colleagues examined the latest batch of seismic signals in combination with first principles simulations and geophysical models to produce their estimates for the size and composition of the Martian core. 

The two studies found that the liquid iron-nickel core of Mars is surrounded by an approximately 150 km-thick layer of near-molten silicate rock, the top of which was previously misinterpreted as the surface of the core. This decrease in core radius implies a higher density than estimated in the earlier InSight study. These estimates can more easily be reconciled with our existing knowledge of chemical abundance on Mars.

“The molten state of this layer suggests that its temperature must be at least 2,000 Kelvin. This could be a sign that Mars had a turbulent interior following its formation, rather than a calmer one that more gently transported and shed heat to interplanetary space,” Suzan van der Lee from Northwestern University, Evanston, Illinois, U.S., writes in an accompanying News and Views article.

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