Scientists Have Revealed the Origin of Most Meteorites

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An international team of researchers has found that 70% of known meteorite falls come from three young asteroid families: Karin, Koronis, and Massalia. These families formed from collisions in the main asteroid belt 5.8, 7.5, and about 40 million years ago, respectively. Notably, the Massalia family accounts for 37% of all known meteorites.

While there are over 70,000 meteorites cataloged, only 6% have been clearly identified by their composition (achondrites) as originating from the Moon, Mars, or Vesta, a large asteroid. The sources of the remaining 94%—mostly ordinary chondrites—had been largely unidentified.

The prevalence of these three young families as meteorite sources can be attributed to their life cycle. Young families have many small fragments left from collisions, increasing the chances of these fragments colliding and escaping the belt toward Earth. In contrast, older asteroid families are “depleted,” having lost most of their small fragments over tens of millions of years due to repeated collisions and dynamic evolution. Eventually, Karin, Koronis, and Massalia will be replaced by newer sources from more recent collisions.

Image by Alex Shuper for Unsplash

This significant discovery came from a telescopic survey of the composition of major asteroid families combined with advanced computer simulations. These simulations analyzed the collisional and dynamical evolution of these families. This research has also identified the primary sources of carbonaceous chondrites and achondrites, in addition to those from the Moon, Mars, and Vesta.

Thanks to this study, the origins of over 90% of meteorites have now been traced. Researchers can also link kilometre-sized asteroids, which pose threats to Earth, to their origins. Many space missions, like NEAR Shoemaker, Hayabusa1, Chang’E 2, Hayabusa2, OSIRIS-REx, DART, and Hera, focus on these objects. Notably, asteroids Ryugu and Bennu, sampled by the Hayabusa2 and OSIRIS-REx missions, are linked to the same parent asteroid as the Polana family.

The origins of the remaining 10% of known meteorites are still unclear. The research team plans to continue their work by characterizing all young asteroid families formed within the last 50 million years.


Sara

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