‘Marsquakes’ shed new light on anatomy of the Red Planet

NASA's InSight spacecraft with its instruments deployed on the Martian surface. NASA/JPL-Caltech

Studying seismic activity on Mars has challenged previous assumptions about the Red Planet, most notably the size and composition of its core.

The new picture has been built up since 2019 using a NASA probe as part of the Mars InSight missionExternal link. Researchers at Switzerland’s federal technology institute ETH Zurich helped develop the seismometer on the probe.

For the first time, researchers “saw” the planet’s inner structure in detail by analysing quake waves from the surface down to the core.

The studies, published in three articles in the journal ScienceExternal link, confirm that Mars probably started off completely molten before cooling into a crust, mantle and core.

But the data suggests that Mars has just one continental plate, compared to seven on Earth. The mantle, underneath the crust, is twice as deep as on our own planet, reaching down to depths of 400-600 kilometres.

Core surprise

But the real surprise is that the Martian liquid core measured 1,840 kilometres in radius, which is 200 kilometres more than previous theories formulated 15 years ago.

“If the core radius is large, the density of the core must be relatively low,” says Simon Stähler, a scientist at ETH Zurich. “That means the core must contain a large proportion of lighter elements in addition to iron and nickel.”

The data “will help determine the formation and evolution of Mars and, by extension, the entire solar system”, according to ETH ZurichExternal link.

“But we’re far from finished analysing all the data – Mars still presents us with many mysteries, most notably whether it formed at the same time and from the same material as our Earth,” says ETH Zurich project leader Domenico Giardini.

Scientists have also yet to discover how Mars lost its magnetic field and surface water. “This will give us an idea of whether and how these processes might be occurring on our planet,” says Giardini.