Young asteroid families as the primary source of meteorites.
basic_science · Level V
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- Record sourced from PubMed, PMID 39415066.
- Also identified by DOI 10.1038/s41586-024-08006-7.
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Abstract
Understanding the origin of bright shooting stars and their meteorite samples is among the most ancient of astronomy-related questions, which at larger scales has human consequences<sup>1-3</sup>. As of today, only approximately 6% of meteorite falls have been firmly linked to their sources (Moon, Mars or asteroid (4) Vesta<sup>4-6</sup>). Here we show that approximately 70% of meteorites originate from three recent break-ups of D > 30 km asteroids that occurred 5.8, 7.6 and less than about 40 Myr ago. These break-ups, including the well-known Karin family<sup>7</sup>, took place in the prominent yet old Koronis and Massalia families and are at the origin of the dominance of H and L ordinary chondrites among meteorite falls. These young families are distinguished among all main belt asteroids by having a uniquely high abundance of small fragments. Their size-frequency distribution remained steep for a few tens of millions of years, exceeding temporarily the production of metre-sized fragments by the largest old asteroid families (for example, Flora and Vesta). Supporting evidence includes the existence of associated dust bands<sup>8-10</sup>, the cosmic-ray exposure ages of H-chondrite meteorites<sup>11,12</sup> and the distribution of the pre-atmospheric orbits of meteorites<sup>13-15</sup>.