Meteoroid shock waves help scientists locate new craters on Mars

Researchers have located new craters on Mars using shock waves caused by clumps of space rock as they tear through the sky and crash into the ground.

The new scars on the face of the planet are the first impact craters that have been detected from the explosion and explosion of meteoroids that bombard another planet. The findings will help scientists build a more accurate picture of how often Mars is hit by rocky debris from the solar system and refine their understanding of the deep internal structure of our planetary neighbor.

“This is the first time we feel and hear an impact on another planet,” said Professor Raphael Garcia, a planetary seismologist at the Higher Institute of Aeronautics and Space at the University of Toulouse in Languedoc.

To see if they could find craters made by incoming meteoroids on Mars, the researchers examined seismic waves recorded by NASA’s InSight lander between May 2020 and September 2021. The probe landed on the barren expanse of Elysium Planitia in November 2018 with a mission to investigate. the structure, crust and impact activity of the planet.

Scientists expected InSight to detect between one and 100 impacts every five Earth years using a sensitive seismometer deployed on the Martian surface. The seismic data recorded by the probe included four impact events that the researchers explored in detail.

By knowing how fast acoustic and seismic waves travel through Martian air and rock, the team estimated how far from InSight the various meteoroids hit the surface. Then they worked on the direction.

The loud impact blast sends sound waves racing across the surface in all directions. These deform the ground imperceptibly, but Insight’s data was so sensitive that the team picked up the direction of the impact from the slight tilt of the seismometer as the sound wave rolled through.

The analysis allowed scientists to predict roughly where incoming meteoroids crashed into the surface. To check for signs of new craters, they turned to images taken by NASA’s Mars Reconnaissance Orbiter. Before-and-after images from this probe revealed new black spots on the ground: newly formed craters near the expected impact sites.

A meteoroid hit Mars on September 5, 2021 and set off three shock waves. The first came when it slammed into the Martian atmosphere at about 10 kilometers per second, creating a shock wave along its path. The space rock then exploded at an altitude of between 13 and 16 km, producing multiple fragments. These then hit the ground, creating a cluster of fresh craters several meters wide.

The data is enormously valuable to planetary scientists studying the structure of the Martian crust because the source of the seismic waves can be located in the crater. But impact craters are also used as cosmic clocks, with older surfaces on planets and moons more cratered than younger ones.

“If people want to know if a surface is older or younger, it’s critical to know the impact rate, but we’re not there yet,” Garcia said. Details are published in Nature Geoscience.

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