Ordinary Chondrites: 1. Short Life of Small Meteorites

The data on the concentration of cosmogenic neon isotopes and the density of cosmic-ray tracks in about 600 ordinary chondrites were analyzed. For ordinary chondrites of all chemical classes, the dispersion of the ratios between cosmogenic isotopes of neon, (²²Ne/²¹Ne)_c, and a fraction of meteorites with high rates of cosmic-ray-track formation were demonstrated to decrease with increasing cosmic-ray-exposure age. Most likely, these effects are related to the fact that chondrites of small exposure ages are more frequent among meteorites with low degrees of shielding (small sizes), probably because smaller meteorites are placed into Earth-crossing orbits faster than larger ones. This, in turn, is attributed to more effective insertion of small asteroid-belt bodies into resonances, most likely due to the diurnal Yarkovsky effect.