Martian meteorite impacts reveal new information about the planet's crust

Martian meteorite impacts reveal new information about the planet’s crust

Data from the impacts of two meteorites on Mars recorded by NASA’s InSight spacecraft provide new insights into the structure of the Martian crust.

NASA’s InSight mission collected data from two meteorite impacts on Mars That sheds new light on the formation of Mars’ crust. In the past, scientists have seen many earthquakes whose waves propagate into the planet’s interior from the epicenter.

Since then, they have been anticipating a circumstance that will also cause waves to travel across the planet’s surface. The moment had arrived on December 24, 2021, when a meteorite struck Mars at a distance of approximately 3,500 km from InSight, causing a crater with a diameter of more than 100 meters and the required surface waves.

A meteor impact that occurred less than 7,500 kilometers from InSight has been identified by researchers as the cause of a second impact. The Institute of Geology and Meteorology at the University of Cologne Dr. Brigitte Knappmayer-Endron and Sebastian Carrasco participated in the evaluation of the information provided by these two events. Science has now published the results.

Researchers estimate surface waves because they reveal details about the formation of Mars’ crust. Mars’ core, mantle, and crust have previously been revealed by body waves that are generated during earthquakes and travel through the planet’s interior. Although the data was collected from only one place on the planet, the crust is expected to have the highest degree of heterogeneity, similar to a land.

According to Dr Doyeon Kim, lead author of the study and associate professor at the Institute of Geophysics at ETH Zurich, “Until now, our knowledge of the Martian crust has been based on measuring just one point under the InSight lander.”

The geophysicist was shocked by the surface wave analysis’ conclusion that Mars’ crust has, on average, a fairly homogeneous structure and high density between the collision sites and InSight’s seismometer. On the other hand, scientists have previously found three layers of the crust and evaluated a lower density just below the probe. The near-surface layer, which is about 10 kilometers thick under InSight and is characterized by low seismic velocities and low density, was not present in the new data, which is noteworthy.

This is the first time researchers have been able to accurately verify that the seismic data obtained by InSight came from distant impacts because the impacts caused very distinct craters to appear in images from orbit. The series of fast orbit images also helped establish useful time constraints on when the craters could be produced. This is a perfect match for the times when seismic waves were captured.

For the first time, seismic imaging and photographic techniques were used in this investigation to record impacts that did not occur on Earth. This may be the reason why there are no surface waves yet, as meteor strikes occur on the surface of the planet. It is possible that sources of deep seismic waves such as earthquakes did not actually produce those waves. Researchers will be better able to identify and categorize meteor impacts in data obtained by InSight and use them in models if they know that specific seismic events are impacts.

Dr. Brigitte Knappmayr-Andron explained: “The new findings are very interesting because the planet’s crust provides important clues about the formation and evolution of celestial bodies. It is the result of early dynamic processes in the mantle and later rocky processes.” It can provide information about conditions billions of years ago and the history of impacts, which were especially frequent in the early days of Mars. ”

The frequency of surface waves determines how fast they can propagate. Because lower frequencies are sensitive to deep depths, measuring how velocity varies across different frequencies in seismic data enables scientists to infer how velocity changes with depth. Since seismic velocity also depends on the elastic properties of the material the waves are traveling through, this can be used to determine the average density of rocks. This allowed scientists to determine the structure of the crust at a depth of 5-30 kilometers below the surface of the planet.

The team was trying to figure out why the average speed of the observed surface waves was much higher than they expected based on an earlier point measurement taken under the Insight rover. Is it due to a difference in the composition of the surface rocks or due to some other mechanism? The paths between the meteor impact and the measurement site traverse one of the largest volcanic regions in the northern hemisphere of Mars, and igneous rocks often have higher seismic velocities.

surface evolution Lava Or the closing of pores due to heating caused by volcanic processes are two examples of the many mechanisms that may accelerate seismic waves. On the other hand, the crust below the InSight landing site may have taken on its characteristic structure as a result of material ejection during asteroid More than three billion years ago, according to the study.

If so, the probe’s core likely won’t be an accurate representation of the overall crustal structure of Mars, according to Kim.

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