Atmospheric Evolution of Terrestrial Planets and Satellites

The evolution of planetary atmospheres and their water inventories are strongly related to the evolution of the solar radiation and plasma environment, which was much more active when the young Sun arrived at the Zero-Age-Main-Sequence. After formation of the terrestrial planets and their early atmospheres, due to the active young Sun and large impacts, heavy species and their isotopes were most likely fractionated to their present values by impact related dynamical escape. Higher solar X-ray and EUV fluxes heated and expanded the thermospheres of the early planets. Under such solar conditions, depending on the thermospheric composition, the amount of IR-coolers and the mass and size of the planet, hydrostatic equilibrium was not always maintained and hydrodynamic flow and expansion of the upper atmosphere resulting in adiabatic cooling of the exobase temperature could develop. Depending on atmospheric protection by magnetospheres, the current atmospheric abundances and isotopic compositions were determined by the action of thermal (Jeans, impact related hydrodynamic escape) and non-thermal (ion pick up, polar outflow, cool plasma flow into the tail, plasma instabilities, sputtering, photochemical loss) escape processes of gases supplied by outgassing during the later evolutionary epochs. Furthermore, it is shown how atmosphere-surface interaction processes such as carbonate weathering, volcanic outgassing, and carbonate recycling, and feedback stabilization under green-house conditions as well as the origin of life play important roles in the evolution of planetary atmospheres.