DIX Planetary Science Seminar

The models that most successfully reproduce the orbital architecture of the Solar System terrestrial planets start from a narrow annulus of material that grows into embryos and then planets. However, it is not clear how this ring model can be made consistent with the chemical structure of the inner solar system, which shows a reduced-to-oxidized gradient from Mercury to Mars and a parallel gradient in the asteroid belt. We propose that there were two primary reservoirs in the early inner solar system: a narrow, refractory-enriched ring inside of 1 au; and a less massive, extended planetesimal disk outside of 1 au, with oxidation states ranging from enstatite chondrites to ordinary chondrites. I will discuss various dynamical processes—most importantly an inwardly sweeping secular resonance—that assemble the terrestrial planets while leaving behind unaccreted planetesimals to be implanted into the asteroid belt. This scenario is uniquely consistent with a wide range of dynamical, chemical, and isotopic constraints for bodies interior to Jupiter and ties together the compositional and orbital architectures of the rocky Solar System.