Solar Cycle and Seasonal Variability of the Martian Thermosphere-Ionosphere and Associated Impacts upon Atmospheric Escape

A growing body of evidence supports an ancient Mars having a milder, wetter climate, suggesting that its atmosphere was once more substantial than it is today. The fate of the lost atmosphere and water is a major unanswered question. Is the “lost” water sequestered in the crust at all latitudes, or did much of it escape to space? While available measurements and theoretical studies suggest that a number of atmospheric escape processes are at work today, little is known about their efficacy, including temporal variations driven by the solar cycle and Mars seasons. Selected 3-D simulations are presented and illustrate the coupling between the thermosphere-ionosphere system and the exosphere leading to predictions of the oxygen corona and hot oxygen escape (a major component of atmospheric loss for present day Mars).