Abstract

That chondrites are the building blocks of terrestrial planets has been the dominant paradigm on terrestrial planet formation. Chondrites are geologically undifferentiated meteorites, whose compositional diversity reflects the complexities of processes in the solar nebula. However, more recently, different processes are investigated that produce chemical compositional changes AFTER the solar nebula/chondrite stage. Two main processes stand out:
i.) collisional erosion, but also ii.) post-nebula volatilization, including possible escape and fractionation of elements and isotopes. The latter affects noble gases (isotopes), atmospheric gases and “moderately volatile elements”, including the radiogenic heat-producing element potassium. Collisional erosion is also critical to the eventual budget of the three heat-producing elements (Th, U and K) in terrestrial planets. In turn, the heat-producing elements determine the planet’s subsequent evolution. The formation scenarios of the young protoplanets, their impact history, the Moon forming impact in the case of Earth as well as possible nebular-based protoatmospheres in relation to the activity history (X-ray, EUV, wind) of the young Sun will be discussed in the workshop. Isotope and Elemental ratios can also be used for constraining the time-scale of accretion, the volatile delivery and the origin of the Moon. Further planetary evolution in relation to the formation of plate tectonics and the influence of life on the origin of Earth’s nitrogen atmosphere will also be addressed. The emergence of life and their relation to the origin of this secondary atmosphere will be discussed within the framework of comparative planetology between the Earth, Venus, Mars and Saturn’s large moon Titan. Consequences for the evolution of Earth-like habitats on other stars will be addressed. Finally, the workshop will conclude with future space missions that are important for enhancing our understanding in terrestrial planet evolution related to the science cases discussed in this workshop.