Meteorites fall on Mars almost every day

In the past, impacts were measured by comparing models that compared observations of meteorite craters on the moon with photographs of Martian craters. By integrating the characteristics of the red planet into the models, it turns out that that comparison was incorrect. Mars is much more massive than the moon, and is much closer to the solar system’s main asteroid belt. This makes Mars a prime target for large rocks wandering through space.

Moreover, the planet, which has almost no atmosphere, cannot count on this protective shield to disintegrate some meteorites or parts of them.

An international team of scientists from ETH in Zurich and Imperial College London has taken a new look at the matter by mapping sounds. “It seems more efficient to listen to the sound of the impacts to determine at what frequency they happen,” said Gareth Collins, co-author of the paper published in Nature Astronomy.

The SEIS (Seismic Experiment for Internal Structure) seismograph, an instrument produced under the supervision of the French CNES (National Center for Space Studies), was installed on Mars in November 2018 and is now used to measure the impacts based on their sound .

The research shows that Mars experiences between 280 and 360 meteorite impacts every year, which leave a crater at least eight meters deep. That’s five times more than what was first thought. Measuring smaller impacts is difficult as the planet experiences sandstorms that often cover the shallower craters and make them invisible.

“The study is the first of its kind to use seismological data to calculate the frequency of meteorite impacts. The results should be taken into account when planning future missions to Mars,” says Professor Domenico Giardini of ETH Zurich. Every month, the planet would be hit by a meteorite impact that would leave a crater 30 meters deep.