Astronomy: Massalia asteroid family may be main source of meteorites |

Two research papers suggest that the most common type of meteorites to reach Earth likely came from a few asteroid breakup events, including the most recent one.naturePublished in

A class of meteorites called ordinary chondrites make up about 80% of the meteorites that hit Earth, some of which participated in a period of violent impact events about 466 million years ago. It is believed that this impact event is what led to the Ice Age. Research has shown that approximately 70% of meteorites found on Earth contain a combination called H chondrite (a stony meteorite rich in iron) and L chondrite (a stony meteorite with a slightly lower iron content). Argon-argon dating of L-chondrite meteorites found on Earth suggests that these samples may have originated from the catastrophic collapse of an asteroid that struck at supersonic speed about 470 million years ago, and it turns out to be quite dramatic.

Michael Marcet and his colleagues collected spectroscopic data on asteroids in the asteroid belt between Mars and Jupiter, and found that the asteroid belt, known as the Massalia family, has a composition very similar to that of terrestrial L-chondrite meteorites. Through computer modeling, the researchers suggest that an impact event fragmented an L-chondrite asteroid about 450 million years ago, leading to the formation of the Massalia family, whose fragments accelerated the meteorite flow.

In a second paper, Miroslav Broz and colleagues showed that the current flow of H and L chondrite meteorites was most likely caused by three recent breakups. These events occurred about 5.8 million years ago, 7.6 million years ago, and 40 million years ago, and resulted in the destruction of asteroids with a diameter of more than 30 kilometers. In particular, Broz et al. showed that the impact formation of the relatively small Karen and Coronis asteroids, as well as a second impact event (about 40 million years ago) in the older Massalia family, has now been inferred and can explain most of the meteorites.

These discoveries help solve the mystery of where the most common meteorites to ever hit Earth came from, and how those impacts affected Earth's history.

Broz, M., Vernazza, B., Marcet, M. et al. Young asteroid families are the main source of meteorites nature 634566-571 (2024). https://doi.org/10.1038/s41586-024-08006-7

doi:10.1038/s41586-024-08006-7

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