The inner structure of Mars, revealed: NASA discovers a molten layer wrapped around the planet’s core – in breakthrough that could provide key clues to its formation

Like Earth, much of Mars’ rocky interior remains somewhat mysterious because the planet’s interior is inaccessible to humans.

But a major new advance could provide new insights into how Mars formed, evolved, and became the barren world it is today.

That’s because two new studies have helped reveal a previously unknown layer of molten wrapping around the planet’s core.

Participating scientists compared it to a “heating blanket” and say the discovery indicates that the core of Mars is likely to be smaller and denser than previously thought.

Their findings have been described as “the most precise and accurate estimates to date of the structure of Mars’ core and mantle.”

“The blanket not only insulates heat coming from the core and prevents the core from cooling, but also concentrates radioactive elements whose decay generates heat,” said Vedran Lekic, a professor of geology at the University of Maryland and co-author of one of the new studies.

“When that happens, the core will likely be unable to produce the convective motions that would create a magnetic field — which could explain why there is currently no active magnetic field around Mars.”

Experts believe that Mars once had a magnetic field similar to Earth’s, which stopped billions of years ago and left behind only patches of magnetism thanks to magnetized minerals in the Martian crust.

Without a protective shield surrounding it, the red planet would then be extremely vulnerable to harsh solar winds, causing it to lose all the water on its surface and rendering it unable to sustain life.

Lekic believes that the difference in internal composition between Earth and Mars is likely to explain why the two planets took very different evolutionary paths, leading to the formation of life on Earth about 3.7 billion years ago.

The researchers said: “The thermal covering of the metallic core of Mars by the liquid layer at the base of the mantle means 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.” The paper’s lead author is Henri Samuel, from the French National Center for Scientific Research.

“These sources could be biotic influences or basal motion resulting from gravitational interactions with ancient satellites that have since disappeared.”

The researchers added that the results will help enhance scientists’ understanding of how terrestrial planets such as Mars and Earth were formed, in addition to revealing more about their components.

The Red Planet’s interior structure was originally mapped by NASA’s InSight mission, a probe that landed on Mars in November 2018 and concluded its mission last year.

However, scientists are still pouring over data from the mission.

This helped reveal the presence of a thin layer of molten silicates – the rock-forming minerals that make up the crust and mantle of both Earth and Mars – surrounding the red planet’s liquid iron core.

With the new discovery of this layer, researchers concluded that the Martian core is likely to be denser and smaller than previous estimates indicated.

This assumption is also supported by geophysical data and analysis of Martian meteorites.

A separate new study by researchers at ETH Zürich in Switzerland also suggests that the liquid iron core is actually surrounded by a 93-mile-thick (150-kilometer) layer of semi-molten silicate rock, the top of which was mistakenly thought to be the surface of the core.

Analysis of measurements from InSight in 2021 suggested that Mars has a low-density core composed of liquid iron and lighter elements such as sulfur, carbon, oxygen and hydrogen.

However, this does not fit with estimates of how abundant these lighter elements were at the time of the Red Planet’s formation.

New studies support theories that Mars once had a molten ocean of magma that later crystallized to produce a layer of silicate melt enriched with iron and radioactive elements at the base of the planet’s mantle.

Experts say that the heat coming from these radioactive elements has significantly changed the thermal evolution and cooling history of the Martian world.

“These layers, if they spread widely, could have very big consequences for the rest of the planet,” Lekic said.

“Their presence 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.”

The two new studies were published in the journal Nature here And here.