Professor Lars Stixrude
The goal of MoltenEarth is the construction of HeFESTo, a comprehensive thermodynamic model of the mantle including melting, vaporization, and core-reaction that will increase 50-fold the pressure range of mantle melting models. HeFESTo will specify the physico-chemical processes that drive magma ocean dynamics, thereby allowing us to test evolutionary scenarios. MoltenEarth will allow us to predict the quantities central to any attempt to understand magma ocean evolution:
The freezing interval of silicate liquids. Over what temperature range do silicate liquids freeze and what is the sequence of crystals that form?
The density of silicate liquids. How does the density of liquids depend on pressure and temperature and how does this compare with coexisting crystals?
The composition of silicate liquids. How are elements partitioned between coexisting liquid and crystal and how does this influence buoyancy?
The vaporization of silicate liquids. What is the nature of the first atmosphere that overlay the magma ocean after the giant impact?
The reaction of silicate liquids with core material. What is the nature of the bottom boundary of the magma ocean? What is the extent and nature of reaction?
MoltenEarth will almost certainly lead to the consideration of new evolutionary scenarios as the full richness of silicate crystallization is included, along with new ways of testing these against present-day observations. It will serve as the basis for evaluating what may be thought of as Earth's initial condition: its state immediately following the moon-forming impact, including the depth of the magma ocean, and nature of its first atmosphere. HeFESTo will point the way towards fossil evidence in the present-day Earth of the magma ocean, and help to decipher the origin and significance of chemical heterogeneity and deep melt in Earth today.