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Theses

L'échappement atmosphérique Martien : analyses des données MAVEN

Abstract : Various observations suggest that Mars permanently loses its atmosphere into space. Several mechanisms have been identified among which atmospheric sputtering is considered a minor process nowadays. A direct measurement of sputtering signature being not accessible with the actual instruments, most of the estimates of its present efficiency are based on analytical or numerical models. They all depend on an accurate knowledge of the ion flux and energy distribution precipitating into Mars’ atmosphere and at the origin of Mars’ atmospheric sputtering. flux. Constraining this precipitating ion flux is therefore a key information to better understand if Mars’ atmospheric sputtering could have been a significant mechanism of atmospheric escape into space. The main goal of my PhD has been to study the measurements obtained by the instruments of the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft to better understand the mechanisms at the origin of the ion precipitation into the Martian atmosphere as well as their dependence on the solar wind and radiation conditions. Thus, I was able to study the influence of solar events on ion precipitation and to isolate its key parameters: the dynamic pressure and the electric field. I then carried out the first study establishing an anti-correlated dependency between ion precipitation and EUV flux. I then studied the influence of dynamic pressure on ion precipitation by comparing the results of MAVEN observations with the results of LatHyS simulations.
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  • HAL Id : tel-03359625, version 1

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Antoine Martinez. L'échappement atmosphérique Martien : analyses des données MAVEN. Planétologie. Sorbonne Université, 2020. Français. ⟨NNT : 2020SORUS347⟩. ⟨tel-03359625⟩

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