Scientists have directly measured the properties of Mars’ core for the first time and confirmed model predictions of its composition. The international research team, which included seismologists from the University of Maryland, used seismic data acquired by the NASA InSight lander to detect seismic waves traveling through Mars’ core, revealing a completely liquid iron-alloy core with high percentages of sulfur and oxygen. This finding sheds new light on how Mars formed and the geological differences between Earth and Mars that may affect planetary habitability.

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 impact, and detected waves that traveled through the planet’s core. By comparing the time it took those waves to travel through Mars 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.

The researchers’ results indicated Mars most likely has an entirely liquid core, unlike Earth’s combination of a liquid outer core and a solid inner core. Additionally, the team inferred details about the core’s chemical composition, such as the surprisingly large amount of light elements (elements with low atomic numbers) — namely sulfur and oxygen — present in Mars’ innermost layer.

The team’s findings have confirmed the accuracy of current modeling estimates that aim to unravel the layers hidden beneath a planet’s surface. Research like this also paves the way for future geophysics-oriented expeditions to other celestial bodies, including planets like Venus and Mercury.

These findings were published in the Proceedings of the National Academy of Sciences (PNAS).

References

• Irving, J. C. E., Lekić, V., Durán, C., Drilleau, M., Kim, D., Rivoldini, A., Khan, A., Samuel, H., Antonangeli, D., Banerdt, W. B., Beghein, C., Bozdağ, E., Ceylan, S., Charalambous, C., Clinton, J., Davis, P., Garcia, R., Domenico Giardini, Horleston, A. C., … Xu, Z. (2023). First observations of core-transiting seismic phases on Mars. Proceedings of the National Academy of Sciences, 120(18), e2217090120. https://doi.org/10.1073/pnas.2217090120

• Jiang, G. (2023, April 24). Scientists Detect Seismic Waves Traveling Through Martian Core for the First Time. College of Computer, Mathematical & Natural Sciences; University of Maryland. https://cmns.umd.edu/news-events/news/scientists-detect-seismic-waves-traveling-through-martian-core-first-time