Oxygen Ablation during Atmospheric Entry: Its Influence on the Isotopic Composition of Micrometeorites

Abstract Micrometeorites (MMs) offer glimpses of the diverse nature parent bodies that accreted during first few million years after formation proto-Sun. The present work explores this by evaluating ablation oxygen from MMs atmospheric entry, and resulting effect on isotopic composition. A Chemical ABlation MODel (CABMOD) combined with measured isotope composition MMs, shows at temperatures below 2000 K a relatively small percentage (∼0%–5%) ablates; temperature is nevertheless sufficient to induce diffusion among different silicate phases MMs. large δ 18 O found within MM types low indicates exchange insignificant entry. Therefore, explain values existing in heated where less than percent, we propose these particles are distinct C-type asteroids have undergone nebular gas and/or aqueously altered their bodies. This supported evidence unmelted not exchanged entry or ablation, but values. However, cosmic spherules does appear vary systematically could be due heterogeneity precursors. investigation overall provides insights into alteration, reservoirs extraterrestrial objects prevailed early solar system.