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Task 4: The Abiotic Planet Model

This task will build on the coupled climate-chemistry model developed in Task 3. The goal of the Abiotic planet model is to explore the range of plausible atmospheres for planets that do not harbor life. Because life detection will require a certain degree of "we'll know it when we see it," it is essential to have an accurate picture of exactly what a life-free planet can potentially look like. Venus and Mars give us two close-up views of what life-free terrestrial planets' atmospheres look like, but there is likely a wide range of atmospheric compositions and climates that can also be present on abiotic worlds. Also, such worlds inevitably do evolve over time as a result of exogenous and geological processes. Therefore, understanding the impact of such processes on the appearance of their atmospheres is a key goal of Task 4.

Task 4 Highlights to Date: This past year saw the addition of melt-generation (for predicting mantle volatile loss to the atmosphere) into the planetary interior/plate tectonics model. Progress was also made on reactive transport models for rock weathering, to help constrain the evolution of mineralogies of other habitable planetary surfaces and their volatile fluxes. Work also continued on a model for hydrodynamic loss processes from planetary atmospheres. Research results included the use of kinetics to predict formation of siderite in soils that develop under slightly oxic conditions, which is contrary to thermodynamic predictions. These results reinforce the conclusion that paleosols formation before 2.4Gya occurred under an atmosphere with less than 30 times the present level of CO2 . Reactive transport modeling also showed that black shale weathering is an important factor in regulating Earth's atmospheric oxygen composition during the Phanerozoic.

Task 4 Results

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