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Monte Carlo Modeling of the Effects of Impact Events on Planetary Atmospheres

Presentation #213.01 in the session Martian Aurora, Atmosphere, Winds, and Dust (Poster + Lightning Talk)

Published onOct 23, 2023
Monte Carlo Modeling of the Effects of Impact Events on Planetary Atmospheres

Planetary atmospheres are an essential component of surface habitability. One important, yet not well understood, process that can alter planetary atmospheres is impact cratering. Bolide impacts can deliver or remove gasses from an atmosphere, depending on the characteristics of the impactor, target, and atmosphere. But do atmospheres tend to shrink or grow due to the net effects of many impacts? If atmospheres tend to shrink due to impacts, then planets in heavily bombarded systems could be less likely to harbor life. Alternatively, if atmospheres tend to grow due to impacts, then bombardment periods could potentially rehydrate planets that have been stripped of their atmospheres. To determine the net effects of many impacts on the atmospheric pressure of planets, we need to consider the details of each impact event, including composition, size, and velocity of the impactor. We also need to track the changing atmosphere of the target body.

In this work, we investigate and compare several models from the literature that describe atmospheric change due to impacts. These models take into account various processes and omit others. The models are also most relevant to different impactor size regimes where various processes dominate. Some of the model size regimes overlap. We combine the models into one composite model, where each model is applied to its preferred impactor size regime. Using this composite model, we study the net effect of many Monte Carlo-generated impacts during a bombardment period on terrestrial planet atmospheres. We find that the models used in the literature produce atmospheric changes that disagree for the same input parameters, sometimes by six orders of magnitude for the change in atmospheric pressure. In addition, if naively applied, several models produce unphysical results. This implies that more work on the interactions between impacts and atmospheres would be useful.

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