Meteorites as big as basketballs they bomb Mars almost every daywith a frequency 5 times greater than that estimated so far. The discovery, published in the journal Nature Astronomy, is thanks to the research group led by the Federal Institute of Technology in Zurich (ETH) and Imperial College London. The estimate is based on seismic data recorded during impacts by NASA’s InSight mission, which will end its mission in December 2022. The study therefore offers a valuable new tool for calculating the rate of impacts on the Red Planet, a fundamental piece of data for being able to safely plan future missions, both robotic and human.
Researchers led by Géraldine Zenhäusern of ETH and Natalia Wójcicka of Imperial College were able to distinguish earthquakes generated by falling meteorites since I am much shorter as compared to those of tectonic origin: while a normal magnitude 3 earthquake on Mars lasts several seconds, an event generated by an impact of the same size lasts only 0.2 seconds or even less, due to the great speed of the collision. In this way, the authors of the study were able to estimate that Mars is hit by between 280 and 360 meteorites every year.
These impacts generate craters at least 8 meters wide almost every daywhile alone about once a month they are formed larger craterswith a diameter also of 30 meters. Since hypervelocity impacts cause explosion zones that are easily 100 times larger than the crater, knowing the exact number of impacts is important for the safety of future missions. Furthermore, seismic data can also help reconstruct the geological history and evolution of the planet: “You could think of them as a sort of ‘cosmic clock‘ – says Wójcicka – to help us date the Martian surfaces and perhaps, later, other planets of the Solar System”.
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