Strong impact gives insight into deep structure of Mars

Strong impact gives insight into deep structure of Mars

This cross-sectional view shows the meteorite impact observed by the Mars Reconnaissance Orbiter on the far side and the resulting propagation paths of the seismic waves, detected by the InSight seismic station, through the mantle and along the core-mantle boundary. Credit: Institut de Physique du Globe de Paris/National Center for Space Studies/N. Starter

NASA’s InSight lander (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) was launched in 2018 with the aim of looking deep inside Mars for the first time to gain important information about the structure and formation of the planet. To help with this task, the lander is equipped with a sensitive seismometer that allows it to detect subtle marsquake vibrations.

By recording the way these vibrations are reflected and bent as they travel through the planet, InSight has helped scientists map the arrangement of Mars’ crust, mantle and core. Recently, an unusual set of vibrations provided an opportunity for even deeper understanding.

In a new article published in Geophysical Research Letters, Durán et al. one of the largest seismic events recorded on Mars and the farthest from the InSight site. It is the first such event, with pressure waves (P-waves) reaching more than 800 kilometers below the planet’s surface into the lower mantle and into the core, where they were diffracted.

After analyzing the vibrations, the authors concluded that the event, which turned out to be an impact, occurred near the Tharsis volcanic plateau on Mars, on the opposite side of the planet from InSight, consistent with satellite imagery showing the show the point of impact.

The depth of the detected vibrations allowed researchers to constrain the structure of the lower Martian mantle in more detail than previously possible. They found that the lower mantle appears to be more variable in both temperature and composition than previous seismic models suggested. But they say more data is needed to determine exactly how and why the thermal and chemical composition of the lower mantle varies.

More information:
C. Durán et al, Observation of a core-diffracted P-wave in a farside impact with implications for the structure of the lower mantle of Mars, Geophysical Research Letters (2022). DOI: 10.1029/2022GL100887

Provided by the American Geophysical Union

This story is republished courtesy of Eos hosted by the American Geophysical Union. Read the original story here.

Quote: Powerful Impact Provides Insight into Deep Structure of Mars (2022 November 15) Retrieved November 15, 2022 from https://phys.org/news/2022-11-powerful-impact-insight-deep-mars.html

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