New Delhi: European researchers have traced the origins of over 90 percent of meteorites, or space rocks that survive their trip through the atmosphere. Previously, only about six percent of meteorites had been linked to a known source. Now, the researchers have shown that 70 percent of all known meteorites originate from three families of asteroids, Karin, Koronis and Massalia. These families of asteroids have similar orbits, and were formed by collision events 5.8, 7.5 and 40 million years ago, and all occupy the Main Belt between Mars and Jupiter. The Karin family of asteroids is a subfamily of the Koronis family.
A chondride group of meteorite found in the Atacama desert in 2011. (Image Credit: Jérôme Gattacceca, CNRS, CEREGE).
The small fragments leftover from the collisions in the orbits occupied by these asteroid families, increases chances of further collisions between the fragments. These smaller, lighter asteroids are also more likely to be deflected on a trajectory that takes them to the Earth. Over tens of millions of years, these fragments erode and evolve, eventually disappearing. The results were possible because of a telescope survey examining the compositions of all the major asteroid families in the main belt, combined with sophisticated computer simulations. The researchers were also able to determine that both asteroid Ryugu and asteroid Bennu, whose samples were returned by USA’s OSIRIS-REx and Japanese Hayabusa 2 missions, originated from the same parent body as the asteroids in the Polana family.
Young families of meteorites
The researchers are now planning to trace the origins of the remaining 10 percent of known meteorites, by characterising all the families of asteroids that formed less than 50 million years ago. The research has been described in one paper in Astronomy and Astrophysics on the origins of carbonaceous meteorites and near Earth objects (NEOs), and two papers in Nature, on the origins of most meteorites from young asteroid families, and the origin of meteorites from the Massalia asteroid family.
