Previous analyses of the meteorites that collide with our planet today suggest some kind of common origin; they are made of very similar materials and were irradiated by cosmic radiation for a suspiciously short time, suggesting a relatively recent detachment from common parent bodies.
The teams of the 3 newly published papers used a combination of superdetailed telescope observations and computer simulations to compare asteroids in space with meteorites found on Earth, matching rock types and orbital paths between them.
Led by researchers from the French National Centre for Scientific Research, the European Southern Observatory and Charles University in the Czech Republic, the studies focused on H (high-iron) and L (low-iron) chondrites - the most common type, making up about 70% of meteorites. They are so called because they are made up of small particles called chondrules that are produced when molten rock cools rapidly. Researchers determined that these H and L chondrite meteorites arrived on our planet from 3 families of asteroids called Masalia, Carin, and Koronis, which are located in the main
asteroid belt between Mars and Jupiter.
One of the research teams was able to put dates on notable collisions in these asteroid families that have triggered new cascades of rocks that will end up on Earth. In the case of Masalia, major collisions occurred 466 million years ago and 40 million years ago, while in the Carin and Coronis families such collisions occurred about 5.8 million years ago and about 7.6 million years ago, respectively.
"Supporting evidence includes the presence of associated dust lanes, the age of cosmic ray exposure of H chondrite meteorites, and the distribution of the meteorites' pre-atmospheric orbits," the authors write in one of the published papers. This means that most meteorites colliding with Earth today are from fewer asteroid groups than expected - and from more recent collisions. These (relatively) recent collisions explain the meteorites that are landing in the current epoch.
"This is partly explained by the life cycle of asteroid families," the team says. The collisions that these asteroid families experience lead to the emergence of a huge number of smaller asteroid fragments, which then increases their chances of further collisions and release from the asteroid belt.
The researchers also looked at other less common meteorites outside of the H and L chondrites, bringing the number of meteorites reported to over 90%. These were assigned to asteroid families including Veritas, Polana and Eos.
This new information could teach astronomers more about the evolution of the solar system and our planets over time, as well as the future paths of asteroids and meteorites. The teams remain determined to continue observing and plotting until all types of meteorites have been accounted for.
"Future work should focus on the few remaining classes - mainly iron meteorites, palamites and ureilites," the researchers write. | BGNES
