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Analysis of Marsquakes Reveals Red Planet’s Unexpectedly Large Core

By Kimbra Cutlip

Mars has a larger molten core and a less dense crust than previously estimated, according to an international team of researchers—including several from the University of Maryland—that conducted the first comprehensive review of seismic wave data collected on the red planet’s surface by NASA’s InSight mission.

The results were published in three papers Friday in the journal Science.

“These studies on Mars are special because, for the first time, we get to reconstruct the interior structure of Mars based on direct observation of geophysical activity,” said Doyeon Kim, a postdoctoral associate in UMD’s Department of Geology and a co-author of the three papers.

Predictions about the interior of Mars have come from observations from orbiting spacecraft, which have provided extensive information about the surface of the planet, but only rudimentary data on what lies below. Previous studies were based on geodetic data, which is indirect data on surface shape and magnetic fields gathered from orbiting the planet, said Quancheng Huang Ph.D. ’20, another co-author of two of the papers from UMD who is now a postdoctoral fellow at New Mexico State University.

The InSight mission seismometer detected 733 distinct “Marsquakes.” Analyses of 35 of those quakes, which registered magnitudes between 3.0 and 4.0, were reported in the three research papers. The research showed that Mars is differentiated much like Earth, with a thin outer crust of brittle rock above a mantle of softer rock and a core that is at least partially molten.

Prior to landing in 2018, the core’s estimated radius was approximately 1,450 to 1,850 kilometers; the seismic data shows it to be about 1,830 kilometers, or at the upper end of the estimate, said Angela Marusiak Ph.D. ’20, a UMD co-author of one of the research papers who is now a postdoctoral scholar at NASA’s Jet Propulsion Laboratory.

UMD contributors also included Associate Professor of Geology Vedran Lekic, a coauthor on the three papers, and Associate Professor of Geology Nicholas Schmerr, a NASA InSight participating scientist co-investigator and the lead investigator for the UMD scientists.

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