So far only 6 percent with over 70 thousand known meteorites managed to be clearly assigned to specific celestial bodies, such as the Moon, Mars or Vesta – one of the largest objects in the asteroid belt. The remaining 94 percent meteorites, mainly the so-called ordinary chondrites, however, had an unknown source. Thanks to new research, however, this mystery has been largely unraveled.
An international team of scientists, led by researchers from CNRS, the European Southern Observatory and Charles University Czech Republicshowed that 70 percent known meteorites come from only three young asteroid families – Karin, Koronis and Massalia. They were shaped by collisions that took place in the asteroid belt respectively 5,8, 7,5 and about 40 million years ago. The largest source of meteorites turned out to be the Massalia family, from which it comes as much as 37 percent all meteorites.
What makes these three young asteroid families responsible for such a large number of meteorite falls? The key to understanding this phenomenon is the life cycle of asteroid families. Young families are characterized by an abundance of small fragments left after collisions. This large number of small fragments and their high mobility increases the risk of further collisions, which may lead to rocks escaping from the asteroid belt towards Earth.
Older asteroid families, formed by past collisions, however, they are already “depleted” sources of meteorites. Fragments from them were largely destroyed or thrown into space as a result of subsequent collisions lasting for tens of millions of years. This process continues constantly, therefore, young asteroid families, i.e. the already mentioned Karin, Koronis and Massalia, will gradually give way to new sources of space rockscoming from subsequent, even more recent collisions.
This discovery was made possible by connection telescopic observations chemical composition of the main asteroid families in the main asteroid belt and advanced computer simulationswhich analyzed both the collisions and the evolution of the studied families of space rocks.
This research allowed us to identify the sources of approximately 90%. known meteoritesbecause in addition to the specimens from the main trio, the origin of other space rocks, originating from older families, was also discovered.
Research works they also shed new light on the origins of dangerous asteroids of Earth-threatening size among others Ryugu and Bennu, which were recently explored by the Hayabusa2 and OSIRIS-Rex probes. It turned out that they came from the same parent plant as the Polana family.
Even though scientists managed to identify the origin of over 90 percent meteorites, origin of the remaining 10 percent still remains a mystery. To unravel this mystery, the team plans further research, focusing on young asteroid families that formed less than 50 million years ago.
Source: geekweek.interia.pl
