Seismic waves crossing the core of Mars reveal details of the Red Planet’s heart


The heart of Mars is about the size of our Moon and almost twice as dense. Roughly, it can be assumed that the first observed noises from an earthquake and a falling meteorite crossed the heart of the Red Planet, researchers report on April 24 in Proceedings of the National Academy of Sciences . Penetrating reverberation allowed the researchers to refine estimates of the core’s size, density, and composition.

“No one had ever seen a seismic wave pass through the core before[Марса]”, says seismologist Jessica Irving from the University of Bristol in England. “We waited over 900 days for one earthquake on the far side,” she says. Then “24 days later there was a … meteorite impact.”

The clam-shaped InSight seismometer — the Seismic Experiment for Internal Structure, or SEIS (shown here) — has been detecting seismic waves from earthquakes and meteorites on the Red Planet until December 2022.JPL-CALTECH/NASA

Both were recorded by NASA’s InSight lander, which has been monitoring seismic activity on Mars for four years, until December 2022. During its 1,480-day career, the lander recorded the tremors of more than 1,000 earthquakes and several collisions. But during all this time he detected only two noises on the far side of the planet.

By analyzing the core-crossing seismicity from the two events, Irving and her colleagues found that the heart of Mars has a radius of 1,780 to 1,810 kilometers with a density of about 6,200 kilograms per cubic meter. This radius is slightly smaller than previously thought, and about half that of all the layers of the Earth’s heart. The cores of both planets make up about half of their total thickness.

In addition, the researchers concluded that the core of Mars is mainly composed of a liquid iron alloy, with sulfur making up about 15 percent of its mass. The share of hydrogen, oxygen and carbon together is about 5 percent. The findings roughly coincide with some previous analyzes of the composition of Martian meteorites.

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