Water and other volatiles are crucial to the development of atmospheres, oceans, and habitable environments on rocky planets. Within the Solar System, the source and timing of delivery of water and other volatiles to the terrestrial planets remains an active area of research. Planetary formation models show that giant impacts play an important role in building terrestrial planets to their present sizes and can occur for up to 100 Myr after the main protoplanetary disk has dissipated. Therefore, processes such as melting and fluid migration on planetesimals and embryos can significantly influence the final water budget of Earth and other Earth-like planets. Following giant impacts, magma oceans interact with massive water-rich atmospheres, which can influence cooling timescales, atmospheric escape, and early ocean compositions. Magma oceans may exist for significantly longer timescales on planets around small M dwarf stars due to their high pre-main sequence luminosities. This is therefore a problem for atmospheric retention of small planets around small stars.<br/><br/>During the primary tectonic phase of a rocky planet, significant amounts of water can be stored within nominally-anhydrous minerals within the planet’s interior. Tectonic activity such as plate tectonics can drive exchange of water between the surface and the interior through melting and transport. Therefore the stability of water on the surface will be influenced by the geology of the planet.<br/><br/>In this talk, we will discuss application of magma ocean models to the stability of water-rich atmospheres on rocky planets in different stellar environments and discuss the implication of planet mass and stellar environment on the deep water cycle of Earth and super-Earth sized planets. Rocky exoplanets may also contain substantially more water than the Earth, and we will discuss some of the implications of this for the geological processes that may occur on such planets.

Water on rocky planets: Atmospheres, oceans, and deep interiors

2019 Fall National Meeting

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