Grant: Discovery Grants Program - Individual

The proposed research is a multi-pronged experimental investigation aimed at understanding the composition, state and core dynamics of Earth, Mercury, Mars and Jupiter's satellites Io and Ganymede. The central parts of these planetary bodies are composed primarily of iron and its dilute alloys of sulfur and silicon. The physical properties of these liquid iron alloys control fundamental processes such as heat flow from the core to the mantle as well as the generation and maintenance of magnetic fields inside their cores. The guiding principle of our approach is that understanding the macro-scale processes that govern global geodynamics pivots on our knowledge of the micro-scale aspects of the mineral physics and chemistry of planetary materials that control them. The research will involve experimental measurements of the electrical resistivity, density and viscosity of liquid iron-sulfur-silicon alloys and analog materials at extreme pressures (20GPa) and temperatures (2500K) in large volume presses to simulate the conditions deep inside these planetary bodies. Additional studies of partitioning of U and Si isotopes between liquid metal and silicate will be carried out. With a planned team of 10 HQP over the period of the proposal, we will employ novel techniques developed in our lab to measure density and viscoity using composite spheres in the sink/float method. Synchrotron x-ray radiography will provide real-time images of the sphere motion in the pressurized liquid. The significance of the results is expected in three areas of deep Earth and planetary studies. 1. The results will help to determine the core compositions of these bodies. 2. The measured physical properties are required for accurate models of the dynamics (geodynamo and heat flow) of the cores of these planetary bodies. 3. The results will directly address the basic physics of constant physical property behavior along the pressure-dependent melting boundary. The proposed studies will help to determine what these planetary bodies are made of and how they work.