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An international team of scientists that included two University of Maryland seismologists observed seismic waves traveling through Mars’ core for the first time and confirmed model predictions of the core’s composition.
Seismic data acquired by the NASA InSight lander showed that Mars has a completely liquid iron-alloy core with high percentages of sulfur and oxygen, according to a study published today in the Proceedings of the National Academy of Sciences. These findings reveal new insights into how Mars formed and geological differences between Earth and Mars that may ultimately play a role in sustaining planetary habitability.
“In 1906, scientists first discovered the Earth’s core by observing how seismic waves from earthquakes were affected by traveling through it,” said UMD Associate Professor of Geology Vedran Lekic, second author of the paper. “With InSight, we’re finally discovering what’s at the center of Mars and what makes Mars so similar yet distinct from Earth.”
To determine these differences, the team tracked the progression of two distant seismic events on Mars, one caused by a marsquake and the other by a large meteorite impact, and detected waves that traveled through the planet’s core. By comparing the time it took those waves to travel through Mars compared to waves that stayed in the mantle, and combining this information with other seismic and geophysical measurements, the team estimated the density and compressibility of the material the waves traveled through.
Additionally, the team, which also included UMD Associate Professor of Geology Nicholas Schmerr, inferred details about the core’s chemical composition, such as the surprisingly large volume of light elements like sulfur and oxygen that the findings suggest comprise one-fifth of the core’s weight. This high percentage varies sharply from the makeup of elements in Earth’s core, indicating that Mars’ core is far less dense and more compressible, and pointing to different conditions of formation for the two planets.
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