A Unified Single-Disruption Model for Terrestrial Accretion, Volatile Delivery, and Lunar Origin

Abstract

Standard solar nebular models face distinct inconsistencies in accounting for the inner Solar System'sstructural and chemical architecture. Specifically, the "Small Mars" anomaly necessitates models like theGrand Tack, which posits a massive clearing of circumstellar mass via Jovian migration. Conversely, theorigin of the Earth-Moon system requires a high-energy collision with a Mars-mass body (Theia), whileEarth's volatile water budget demands late-stage delivery from beyond the primordial snow line. This paperproposes a single, unified hypothesis: the breakup of a volatile-rich, differentiated protoplanet situated nearthe primordial Frost Line (~2.8 AU). We demonstrate mathematically that the inward scattering of thisdisrupted mass simultaneously accounts for the 2.8 AU planetary gap, the mass deficit of Mars, the singleevent volatile hydration of Earth, and the orbital and isotopic dynamics of the Earth-Moon system, offeringa parsimonious alternative to multiple uncorrelated catastrophic events.