Scientists have made a major breakthrough in understanding the origins of most meteorites that fall to Earth.
A team of international researchers, including scientists from the CNRS, European Southern Observatory (ESO), and Charles University, discovered that 70% of meteorites come from just three asteroid families: Karin, Koronis, and Massalia.
These asteroid families were formed by large space collisions in the asteroid belt, which took place 5.8, 7.5, and about 40 million years ago.
The asteroid belt is a region between Mars and Jupiter that contains many rocky bodies, and when collisions occur, pieces break off and may eventually fall to Earth as meteorites.
The scientists found that a specific family, the Massalia family, is responsible for 37% of all known meteorites.
There are more than 70,000 meteorites known to scientists, but only 6% had been identified as coming from the moon, Mars, or the asteroid Vesta, which is one of the largest bodies in the asteroid belt. Most meteorites are called “ordinary chondrites,” but their exact sources had been a mystery – until now.
The reason why these three asteroid families have produced so many meteorites has to do with how young they are.
When collisions happen, they create a lot of small fragments. Over time, these fragments are more likely to bump into each other and get pushed out of the asteroid belt, heading toward Earth.
Older asteroid families, which were formed long ago, have already lost most of their fragments, so they don’t produce as many meteorites anymore.
As these young families keep evolving and losing fragments, newer asteroid families from more recent collisions will take over as the main sources of meteorites.
The researchers used powerful telescopes to study the composition of the large asteroid families in the asteroid belt.
They also ran computer simulations to understand how these families formed and how their fragments evolved over time. This helped them connect specific meteorites to their asteroid families.
Thanks to this work, scientists can now trace the origins of more than 90% of meteorites. The study also helps scientists understand where large, dangerous asteroids—ones that could threaten life on Earth—come from. These asteroids are being studied by many space missions, including Japan’s Hayabusa2 and NASA’s OSIRIS-REx, which recently collected samples from the asteroids Ryugu and Bennu.
While the origins of 10% of meteorites are still unknown, the team plans to continue their research by studying asteroid families that were formed less than 50 million years ago. This could help identify the sources of even more meteorites in the future.
This exciting discovery brings us closer to understanding the origins of the meteorites that have impacted Earth and helps us better track potential future threats from space.
