Review of asteroid, meteor, and meteorite-type links

Abstract

With the goal to determine the origin of our meteorites in the asteroid belt, video and photographic observations of meteors have now tracked 75 meteorite falls. Six years ago, there were just hints that different meteorite types arrived on different orbits, but now, the number of orbits (N) is high enough for distinct patterns to emerge. In general, 0.1–1-m sized meteoroids do not arrive on similar orbits as the larger ~1-km sized near-Earth asteroids (NEA) of corresponding taxonomic class. Unlike larger NEA, a group of H chondrite meteoroids arrived on low-inclined orbits from a source just beyond the 5:2 mean-motion resonance with Jupiter (N = 12), three of which have the 7 Ma cosmic ray exposure (CRE) age from a significant collision event among H chondrites. There is also a source of H chondrites low in the inner main belt with a ~35 Ma CRE age (N = 8). In contrast, larger H-like taxonomic S-class NEA arrive from high-inclined orbits out of the 3:1 resonance. Some H chondrites do so also, four of which have a 6 Ma CRE age and two have an 18 Ma CRE age. L chondrites arrive from a single source low in the inner main belt, mostly via the ν₆ secular resonance (N = 21), not the 3:1 resonance as most L-like NEA do. LL chondrites arrive too from the inner main belt (N = 5), as do larger LL-like NEA. CM chondrites are delivered from a low i < 3° inclined source beyond the 3:1 resonance (N = 4). Source asteroid families for these meteorite types are proposed, many of which have the same CRE age as the asteroid family's dynamical age. Also, two HED achondrites are now traced to specific impact craters on asteroid Vesta.