Martian Atmospheric Losses over Time

[BjarneModerator Super Nova]

Modeling Martian Atmospheric Losses over Time: Implications for Exoplanetary Climate Evolution and Habitability

In this Letter, we make use of sophisticated 3D numerical simulations to assess the extent of atmospheric ion and photochemical losses from Mars over time. We demonstrate that the atmospheric ion escape rates were significantly higher (by more than two orders of magnitude) in the past at ∼4 Ga compared to the present-day value owing to the stronger solar wind and higher ultraviolet fluxes from the young Sun. We found that the photochemical loss of atomic hot oxygen dominates over the total ion loss at the current epoch whilst the atmospheric ion loss is likely much more important at ancient times. We briefly discuss the ensuing implications of high atmospheric ion escape rates in the context of ancient Mars, and exoplanets with similar atmospheric compositions around young solar-type stars and M-dwarfs.

 
Disse modelberegninger for Mars viser, at tab af både ioner og atomer fra marsatmosfæren var 100 gange højere for 4 milliarder år siden. Den store tabsrate skyldes en kombination af en kraftigere solvind og en større ultraviolet flux fra den unge sol. Da M-dværgstjerner generelt har en højere ultraviolet flux i forhold til den visuelle flux end Solen, må man forvente et megert højere atmosfæretab for exoplaneter omkring M-stjerner. Dette kan have stor betydning for sådanne planetsystemers muligheder for at understøtte udviklingen af liv.

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