Exploring the Equations of State of Planetary Mixtures

Fuzzy boundaries may be common in the interiors of large mass and/or very hot planets. These boundaries are characterized by gradual changes in density, reflecting the dissolution of different materials. Jupiter’s rocky core has a fuzzy boundary with its hydrogen-rich atmosphere, and the interiors of the ice giants in the Solar System and large mass exoplanets may have similar features. Such planets can have interfaces composed of rock and ices, rock and water, rock and hydrogen, or metals and rock. Currently, there are little data on mixtures compared to their end member counterparts. To understand how these boundaries behave and interact, we have begun to investigate the equations of state of mixtures by utilizing both lab data and theoretical approaches. We are using a complimentary set of gas gun experiments and the Sandia Z Machine. The Z-to-Planets project is planning to obtain data points on sodium silicate & water mixtures to complement the data currently available for major ices such as water, methane, ammonia, and other ice mixtures (e.g., ‘synthetic Uranus’ compositions). We plan to expand the equations of state for ice mixtures and water-rock mixtures through shock-and-release experiments and by double-shocking methane and silicate mixtures to states near planetary isentropes.

SAND2023-12203A