Speaker: Dr. Gilbert Collins (Lawrence Livermore National Lab)

Abstract:

The recent discovery of more than a thousand planets outside our Solar System together with new capabilities to compress matter up to billions of atmospheres of pressure for fusion research, are opening a new chapter in planetary science. In Earth’s core, (~0.4 TPa or 4 million atmospheres) energy densities are comparable to those of the chemical bond, so chemistry is fundamentally different than on Earth’s surface. The deep interiors of many extrasolar planets (1-10’s of TPa or 10-100’s of millions of atmospheres) are at atomic scale pressures where core electrons (not only valence electrons) can influence the structure and bonding, and can drive new complexities in matter. Experiments are now recreating these extreme conditions in the laboratory to provide new constraints on planetary evolution models. For example, structural and mechanical data for TPa solids are providing compositional insight for terrestrial planets. New melt curve data show several silicates and iron have comparable melting temperatures near 0.5 TPa, suggesting molten silicates coexist with liquid iron alloys in large rocky planets in a magma-ocean stage that last well-beyond the period of formation. Silicates, oxides and helium hydrogen mixtures show chemically complex metallic liquids in the TPa regime, providing insight into potential magnetic field generation for terrestrial planets and the evolution of gas giants. Together, a new generation of experiments recreating core conditions of Solar and extrasolar planets is opening a new frontier for planet exploration.