Source regions of meteorites and near-Earth asteroids

For several decades, the main asteroid belt has been known to be the primary source for near-Earth asteroids (NEAs) and meteorite-dropping fireballs. The qualitative understanding of the evolution of main-belt asteroids to NEAs has allowed the construction of quantitative evolutionary population models for NEAs that describe their source regions (and/or escape routes) in the asteroid belt as well as debiased distributions of NEA orbits, absolute magnitudes, and geometric albedos. One of the primary goals with such evolutionary models has long been to link the compositional data on NEAs and meteorite falls back to the asteroid belt. Ultimately, the goal is to set constraints on the compositional distribution in the primordial asteroid belt. I will first describe the latest one of the evolutionary models of the NEO population (Granvik et al. 2018, Icarus 312, 181) and highlight the main improvements compared to the previous generation of models. In particular, I will explain how the modeling of the available observational data has met and surpassed our initial goals and is starting to reveal geophysical information about asteroids. I will then present selected results that utilize the new model such as establishing the source regions for meteorite falls and NEAs, and correlating that information with their compositions and other physical data. The debiased orbit and absolute-magnitude distributions also allow us to assess the long-term impact rate onto terrestrial planets and to compare the predicted impact rates with the observed crater record. Finally, I will discuss future improvements to the models as well as the relevant observational data that is expected to become available within the next decade.