Making terrestrial planets
Understanding the formation and early evolution of terrestrial planets is one of the most important goals in sciences. The objectives of this proposal, METAL (Making tErresTriA pLanets), are to study the accretion and differentiation processes that have shaped the present composition of the Earth, Moon, Mars and differentiated asteroids including understanding the origin, and timing of delivery of their volatile and siderophile elements. To reach this goal we have identified the best-suited isotopic tools, which are sensitive to the different physico-chemical processes acting at different stages of planetary formation. This work will involve: 1) Development and use of new cutting-edge stable isotope systems for moderately volatile elements (e.g. In, Sb, Sn) in terrestrial, lunar and meteoritic materials, in order to constrain the origin of solar system’s volatile element depletion. 2) Quantifying experimentally the isotopic effects during metal/silicate partitioning and evaporation in all conditions relevant to planetary accretion and differentiation. 3) Building a physical model of volatile loss. 4) Studying the timing, proportions, fate and nature of the material that accreted to Earth and Mars after core formation (i.e. the late-veneer) by using a new method based on the stable isotopes of a highly siderophile element, Pt. This high-risk high-rewards approach seeks to link innovative novel isotopic systems, experiments under extreme conditions, and dynamical modelling, to solve long-standing major scientific questions related to the formation and evolution of the terrestrial planets.