Seismic study reveals Mars bombarded by meteorites daily

Swiss scientists have examined the issue of meteorites striking the surface of Mars. It turns out that such events occur extraordinarily frequently. The striking objects cause the formation of large craters almost daily.

Scientists from the Federal Institute of Technology in Zurich, along with an international team of researchers, have used seismic data for the first time to study meteorite impacts on Mars. Based on the data, they estimated how many meteorites strike the planet's surface daily. Mars experiences meteorite impacts the size of a basketball.

Their results show that Mars is bombarded by 280 to 360 meteorites every year, creating craters more prominent than 8 metres. Furthermore, a crater of approximately 8 metres forms on Mars almost daily, and a 30-metre crater forms on average once a month.

"This rate was about five times higher than the number estimated from orbital imagery alone. Aligned with orbital imagery, our findings demonstrate that seismology is an excellent tool for measuring impact rates," says Dr Géraldine Zenhäusern, co-author of a paper published in the journal "Nature Astronomy".

In their research, scientists utilised a seismometer placed on Mars during NASA's InSight mission. The results obtained in this way were compared with observations of craters conducted by the Mars Reconnaissance Orbiter. Previously, studies on meteorite impacts on Mars were based solely on orbital research and knowledge gained from observations of the Moon.

However, studying Mars is significantly more challenging than learning about the Moon, not just because of the distance but also due to the atmosphere, which, over time, erases traces of meteorite impacts on the surface. Moreover, as scientists explain, less than half of Mars' surface is covered by flat terrain where craters are well visible.

Scientists remind us that an average of 17,000 meteorites fall to Earth yearly, but they are rarely noticed because most disintegrate in the atmosphere. Mars's atmosphere is different because it is 100 times thinner than Earth's.

Knowing the number of meteorites reaching the surface of Mars is essential not only from a scientific perspective. It will also allow for estimating the safety of future Martian missions, both robotic and manned.

"This is the first paper of its kind to determine how often meteorites impact the surface of Mars from seismological data -- which was a level one mission goal of the Mars InSight Mission," emphasises Prof. Domenico Giardini, one of the scientists involved in the project.