The origin and distribution of volatile elements such as carbon, hydrogen, sulfur, and nitrogen in differentiated planetary bodies are key in our understanding of planetary differentiation,…

This federal grant award to William Marsh Rice University, located in Houston, Texas, is focused on understanding the distribution and behavior of volatile elements like carbon, hydrogen, sulfur, and nitrogen during the formation and evolution of planetary bodies. The $475,000 grant, awarded by the National Aeronautics and Space Administration (NASA), involves experimental and modeling work to study how these volatiles partition between metallic cores, silicate mantles, and atmospheres during magma ocean stages of terrestrial planets and other solar system bodies. The research aims to shed light on the initial budgets and distribution of these key elements, which is critical for understanding planetary differentiation, habitability, and comparative planetology. This grant contributes to NASA's "Emerging Worlds" program, which seeks to understand the formation and evolution of the Sun's family of planets, satellites, and minor bodies. No set-aside designation is mentioned.

The origin and distribution of volatile elements such as carbon, hydrogen, sulfur, and nitrogen in differentiated planetary bodies are key in our understanding of planetary differentiation, habitability, and comparative planetology. IT is through the exchange of these volatiles the interiors and the surface environment of planets, satellites, and minor bodies communicate. One of the key questions related to the budget and distribution of c-o-h-s-n volatiles in various terrestrial planetary bodies in general and in the near-surface environments of rocky planets in particular is the behavior of these volatiles during accretion and subsequent large scale melting and core formation, in other words the fate of these volatiles during magma ocean stage of these bodies. The partitioning of c-o-h-s-n volatiles in reduced silicates and alloy melts were key in determining the boundary condition for subsequent evolution of volatiles between the metallic core, silicate mantle, and atmosphere of terrestrial planets. Here we propose to build on our previous and current experimental campaign to constrain the relative partitioning of carbon, nitrogen, and sulfur between FE-rich alloy melt and reduced silicate melts at conditions approaching those of postulated magma oceans of various planetary bodies. The main goal is to build a framework to answer fundamental questions such as why and how the different solar system bodies acquire vastly different budgets and distribution of volatile mixes between the mantle and the metallic core and how the presence of one or more light volatile elements affect the fractionation behavior of the other. Several distinct experimental tasks will be undertaken, all centered on the behavior of carbon, nitrogen, and sulfur and their interplay in magma oceans. The experiments will be conducted using piston cylinder and multi anvil devices and generated samples will be analyzed using a range of micro analytical techniques. The proposed tasks are (1) constraining the partitioning and relative fractionation of c and s in multicomponent FE-rich alloy and silicate melt as a function of oxygen fugacity (FO2) and as a function of p (2-15 GPA) and t (1500-2200 c) as well as saturation of carbon in multi-component alloy melts. (2) constraining the mutual solubility and partitioning of c, n, and s in alloy melt-silicate melt systems as a function of variable sulfur and silicon contents of the alloy melt. (3) taking mercury as an analog of a reduced, sulfur-rich body, constraining c solibility at graphite saturation at different oxygen fugacity conditions (e.g., IW to IW-7 buffers) for FE-poor basaltic melts similar to those found on mercury s surface and in the presence of s. (4) using the obtained experimental data, modeling will be done understand the early core-mantle fractionation of carbon, nitrogen, and sulfur during accretion of different bodies in the solar system. For all the proposed tasks, pressure-temperature conditions will be chosen and varied to specifically target and encompass estimated conditions of magma oceans of putative inner solar system bodies and planets. The goal is to compare and contrast the early evolution of c-o-h-SN volatiles during high pressure-temperature processes of accretion and early differentiation of various solar system bodies. The proposal is extremely relevant for the emerging worlds program as the proposed research aims to understand the formation and early evolution of the solar system bodies in terms of fractionation of volatile elements. The strategic science question of the program is: "how did the sun s family of planets, satellites, and minor bodies form and evolve?", which is what the first order question that will be addressed through the proposed research. The combined experimental-analytical-modeling approach adopted in the proposal will shed light onto the initial distribution of carbon, nitrogen, sulfur, and hydrogen in the main reservoirs of various rocky bodies.