New research shows that approximately 70% of meteorites originate from at least three recent break-ups of massive asteroids.
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This is an artist’s impression of an asteroid breaking up. Credit: NASA / JPL-Caltech.
A class of meteorites called ordinary chondrites make up around 80% of meteorites that have impacted Earth, including those involved in an intense period of impact events approximately 466 million years ago that appear to have triggered an ice age.
Previous research has demonstrated that about 70% of meteorites on Earth have compositions known as H and L chondrites.
Argon-argon dating of L chondrite meteorites on Earth revealed that these samples likely originated from the catastrophic disruption of a single asteroid that experienced a supersonic impact approximately 470 million years ago.
In a new study, Dr. Michael Marsset, a researcher at ESO and MIT, and colleagues compiled spectroscopic data of asteroids in the main belt between Mars and Jupiter.
They found that a group of asteroids known as the Massalia family is closely similar to the composition of L chondrite meteorites on Earth.
Through computer modeling, they propose that an impact event broke up an L chondrite asteroid approximately 450 million years ago, forming the Massalia family and providing the debris that fuelled the meteorite influx.
In a second study, Charles University researcher Miroslav Brož and colleagues found that the current influx of H and L chondrite meteorites was likely caused by three more recent breakups.
These events occurred about 5.8, 7.6, and 40 million years ago, and saw the destruction of asteroids larger than 30 km (18.6 miles) in diameter.
More specifically, they deduced that the collisional formation of the relatively young Karin and Koronis asteroid families, and a second collisional event (about 40 million years ago) in the older Massalia family, explain the majority of the meteorites currently falling to Earth.
In a third, follow-up study, Dr. Brož and co-authors extended their approach to all meteorite families, revealing the primary sources of the carbonaceous chondrites and achondrites, which come in addition to those from the Moon, Mars, and Vesta.
“Our findings offer insights into the mysteries surrounding where the most common meteorites that have impacted Earth so far came from and how those impacts may have shaped Earth’s history,” they said.
The results appear in three papers in the journal Nature and the journal Astronomy & Astrophysics.
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M. Marsset et al. 2024. The Massalia asteroid family as the origin of ordinary L chondrites. Nature 634, 561-565; doi: 10.1038/s41586-024-08007-6
M. Brož et al. 2024. Young asteroid families as the primary source of meteorites. Nature 634, 566-571; doi: 10.1038/s41586-024-08006-7
M. Brož et al. 2024. Source regions of carbonaceous meteorites and near-Earth objects. A&A 689, A183; doi: 10.1051/0004-6361/202450532
