Investigating the thermal histories of terrestrial planets using 3D numerical models

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The terrestrial planets and large moons of the gas giants each exhibit surficial manifestations of their evolving interiors. The driving force for their internal activity is heat. Although some of the heat is a remanent of that generated during planetary formation and the bombardment of the young planets by meteorites during the early history of the solar system, the majority results from sources and processes still in place today. The most important of these heat sources is radiogenic heating from Uranium, Thorium and Potassium in planetary mantles (the thick rocky shells surrounding the metallic cores of the solid planets). Another important source of heat in two of the the satellites of Jupiter (Io and Europa) and possibly Mercury is tidal heating due to the gravitational forces associated with Jupiter and the Sun, respectively. The result of all of this heat being trapped in a planetary mantle is a process called mantle convection, a phenomenon that allows the silicate rocks comprising a rocky mantle to flow, over geologic time scales, like cooking oil on a slow boil. In order to study mantle convection, a process that has been ongoing in most of the solid planets and moons since their formation, we can employ sophisticated computer models that solve the equations governing convection in fluids with the properties of hot silicate rocks. As a result we can study the origin of numerous natural processes effecting planetary evolution. For example, on Earth, internal motion results in surface motion (what we call plate tectonics and continental drift) and studying mantle convection provides insights into the processes responsible for volcanism, earthquakes and mountain building. In addition, mantle convection influences planetary magnetic fields, surface topography, gravitational fields, and, again in the case of the Earth, the formation of mineral and hydrocarbon resources and the planet's climatic system, thus influencing cycles of environmental and biological evolution. Accordingly, the study of each of these disciplines reveals some expression of mantle convection and, conversely, our evolving understanding of mantle convection may affect conventional views of a diverse range of fields in the Earth and planetary sciences.