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Small bodies are time-capsules of different eras of solar system history from the most primitive materials within the solar system to evolved pieces of larger bodies. A small body sample return program is an essential component of small body exploration, and such a program should include opportunities for both missions and laboratory analysis., Comment: A White Paper submitted to the Planetary Science and Astrobiology Decadal Survey 2023-2032

International audience; Previous simulations of planet formation utilizing single bodies including pebble accretion and planet migration imply that giant planets found in orbits exterior to 1 AU originate from the outer regions of protoplanetary discs (30-40 AU). Here we generalize such models to include the mutual gravity between a high number of growing planetary bodies. We investigate how the formation of planetary systems depends on the radial flux of pebbles through the protoplanetary disc and on the planet migration rate. Our N-body simulations confirm previous findings that giant planets originate from 30-40 AU when using nominal type-I and type-II migration rates and a pebble flux of approximately 100-200 Earth masses per Myr, enough to grow Jupiter within the lifetime of the solar nebula. However, planetary embryos growing interior to 30-40 AU also grow and migrate inwards to the inner system (r

The growth and composition of Earth is a direct consequence of planet formation throughout the Solar System. We discuss the known history of the Solar System, the proposed stages of growth and how the early stages of planet formation may be dominated by pebble growth processes. Pebbles are small bodies whose strong interactions with the nebula gas lead to remarkable new accretion mechanisms for the formation of planetesimals and the growth of planetary embryos. Many of the popular models for the later stages of planet formation are presented. The classical models with the giant planets on fixed orbits are not consistent with the known history of the Solar System, fail to create a high Earth/Mars mass ratio, and, in many cases, are also internally inconsistent. The successful Grand Tack model creates a small Mars, a wet Earth, a realistic asteroid belt and the mass-orbit structure of the terrestrial planets. In the Grand Tack scenario, growth curves for Earth most closely match a Weibull model. The feeding zones, which determine the compositions of Earth and Venus follow a particular pattern determined by Jupiter, while the feeding zones of Mars and Theia, the last giant impactor on Earth, appear to randomly sample the terrestrial disk. The late accreted mass samples the disk nearly evenly., Comment: Accepted for publication in Early Earth an AGU Monograph edited by James Badro and Michael J. Walter