Loss of atmosphere from Mars due to solar wind-induced sputtering

Abstract

Because Mars does not have a strong intrinsic magnetic field, the atmosphere is eroded by interactions with the solar wind. Early solar-system conditions enhanced the sputtering loss. It is calculated that ∼3 bars of carbon dioxide (CO2) have been sputtered over the last 3.5 billion years. This significant increase over the previous estimate by Luhmann et al, of ∼0.14 bar of CO2 is the result of the development of a more complete model. The model also predicts slightly greater loss of water-∼80 meters instead of the ∼50 meters predicted by Luhmann et al. Because estimates of CO2 on early Mars range from 0.5 to 5 bars, the 0.14-bar estimate is insignificant but the ∼3-bar estimate will have a large effect on our understanding of the planet's evolution.