Seismic data from Mars indicates that our neighboring planet is hit about three hundred times a year by meteorites the size of basketballs.

A study authored by researchers from Imperial College London and ETH Zurich was able to use data collected from NASA's InSight Lander, which is equipped with a seismological tool termed the Seismic Experiment for Interior Structure (SEIS). It's the only seismometer on Mars, and a crucial source of info pertaining to the biggest events that happen on and under the surface of Mars, including meteorite impacts.

While craters are obvious evidence of a meteorite hitting the surface of the red planet, the study says seismic activity might be a more accurate way of figuring how often Mars is hit by meteorites. The meteorite impacts cause high frequency marsquakes, distinct from other seismic events.

The researchers were able to log three meteorite impacts before their craters were spotted, lending credibility to the theory that seismometers provide better evidence for meteorite crash sites than visual confirmations of craters, which can be as small as just a few meters across. The new data based on marsquakes suggests Mars is hit by meteorites between 280 and 360 times a year.

Meteorite impacts are an important metric for determining planetary age since older surfaces have more craters than younger ones. This method has already been applied to the Moon, though the calculations differ for Mars since it has a thin atmosphere that can disintegrate small meteorites, along with its much different position in the solar system.

"You could think of it as a sort of 'cosmic clock' to help us date Martian surfaces," said Natalia Wojcicka, co-author and Imperial College London research associate. "And maybe, further down the line, other planets in the solar system."

Incidentally, meteorites are also theorized to be a useful source of creating oxygen on Mars itself rather than importing it or the materials needed to make oxygen from Earth, so being able to find more of them would be useful if humans ever actually colonize the planet.

Seismic data is useful for other purposes too

Wojcicka says installing more seismometers, even if they're simpler than SEIS, would go a long ways toward collecting more data on meteorite impacts as well as other seismic activity. "On Earth, you can more easily understand the inner structure of our planet by looking at data from seismometers placed all around the globe," she said.

"To better understand Mars's inner structure, we need more seismometers distributed across the planet."

The most recent research into the innards of Mars based on seismic data suggests it has a smaller and denser iron core - surrounded by more molten rock - than previously thought. On the whole, the inner composition of Mars isn't too different from Earth's, which also has a ferric core enclosed in molten minerals and rock.

SEIS recently detected the largest seismic event ever recorded on Mars, which one study says is an indication that parts of the planet's crust are under high stress and can create marsquakes. ®

https://www.theregister.com//2024/06/29/mars_meteorite_impacts/