Researchers have stated that a liquid silicate “blanket” surrounding the core of Mars provides new insights into the planet’s history and why it lacks life.
An international team of researchers has published findings in the journal Nature that shed light on how Mars formed, evolved, and became the desolate planet it is today.
NASA’s InSight mission to Mars, launched in 2018, has helped scientists map out the planet’s internal structure, including the size and composition of its core, and has provided general information about its turbulent formation.
The mission officially concluded in December 2022 after over four years of collecting data on Mars, but analysis of its observations is ongoing.
The published findings, which challenge the initial estimates of the Red Planet, are derived from the analysis of a significant meteorite impact observed by the InSight mission in September 2021.
The journal describes the use of seismic data to locate and identify a thin layer of molten silicates – rock-forming minerals that constitute the crust and mantle of Mars and Earth – situated between the Martian mantle and core.
By discovering this molten layer, the researchers have concluded that Mars’ core is denser and smaller than previously estimated, aligning better with other geophysical data and analysis of Martian meteorites.
The molten layer is likened to a “heating blanket” by Vedran Lekic, a geology professor at the University of Maryland and co-author of the paper, which covers the Martian 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,” he said.
“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.”
Without a functional protective magnetic field, a terrestrial planet like Mars would be highly susceptible to harsh solar winds and lose all the water on its surface, rendering it incapable of supporting life, according to Prof. Lekic.
He added that the difference in internal structures between Earth and Mars could explain why life exists on one planet and not the other.
The paper’s lead author, Henri Samuel, a scientist at the French National Centre for Scientific Research, stated: “The thermal blanketing of Mars’ metallic core by the liquid layer at the base of the mantle implies that external sources are necessary to generate the magnetic field recorded in the Martian crust during the first 500 to 800 million years of its evolution.
“These sources could be energetic impacts or core motion generated by gravitational interactions with ancient satellites which have since disappeared.”
The team stated that their conclusions support theories that Mars was once a molten ocean of magma that later solidified to produce a layer of silicate melt enriched in iron and radioactive elements at the base of the Martian mantle.
According to the paper, the heat emitted by the radioactive elements would have significantly affected the thermal evolution and cooling history of the red planet.
“These layers, if widespread, can have significant consequences for the rest of the planet,” said Prof. 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.\”
“This new discovery of a molten layer is just one example of how we continue to learn new things from the completed InSight mission.
“We hope that the information we’ve gathered on planetary evolution using seismic data is paving the way for future missions to celestial bodies like the moon and other planets like Venus.”