Mars' Hidden Layers: Seismic Data Reveals Molten Silicate Blanket

A recent study published in Nature attempts to examine a remarkable discovery regarding the existence of a molten silicate layer resting on top of the metallic core of Mars. This study challenges previous research regarding the internal structure of Mars based on data gathered by the now-retired NASA InSight mission and holds the potential to help scientists gain better insights into both the formation and evolution of the Red Planet.

This previous research includes an October 2022 study that used surface waves emanating from two meteorite impacts on Mars to learn about the Martian crust and an April 2023 study that used seismic data from InSight to take the first direct measurements of the Martian core. However, this new study presents findings that the core of Mars is both smaller and denser than previously hypothesized, noting the existence of a molten layer that lies between the Martian mantle and core.

“The blanket not only insulates the heat coming from the core and prevents the core from cooling, but also concentrates radioactive elements whose decay generates heat” said Dr. Vedran Lekic, who is a professor of geology at the University of Maryland and a co-author on the recent study. “And when that happens, the core is likely to be unable to produce the convective motions that would create a magnetic field—which can explain why Mars currently doesn’t have an active magnetic field around it.”

Artist rendition of the molten silicate layer that potentially exists on top of the core of Mars with the lines depicting seismic waves collected by the NASA InSight lander (left) from meteorite impacts (top). (Credit: IPGP-CNES)

The lack of a magnetic field on Mars means the surface is constantly bombarded with solar radiation, leading to a lack of liquid water across its surface but making it inhospitable for life, as well. This is in stark contrast to the Earth, whose magnetic field shields us from this harmful radiation while allowing liquid water and life to be sustainable, as well. The team’s findings indicate that the heat produced by the radioactive elements at this newly discovered molten layer could have significantly changed how the Red Planet cooled over time, which could have led to the disappearance of its magnetic field.

“These layers, if widespread, can have pretty big consequences for the rest of the planet,” said Dr. Lekic. “Their existence can help tell us whether magnetic fields can be generated and maintained, how planets cool over time, and also how the dynamics of their interiors change over time.”

While Mars is a very cold and dry planet today, with an atmosphere just a fraction of Earth’s, things were much different billions of years ago after the Red Planet’s initial formation. During this time, active volcanoes replenished the atmosphere, and an active core produced a magnetic field that shielded the surface from harmful radiation, allowing liquid water to cascade across the surface. However, as the cored cooled, the magnetic field was lost and the volcanism ceased, resulting in the dead planet we see today.

What new discoveries will scientists make about Mars and its formation and evolution in the coming years and decades? Only time will tell, and this is why we science!

As always, keep doing science & keep looking up!