The Observed Properties of H in the Upper Atmosphere of Mars

Hydrogen atoms in the upper atmosphere of Mars originate from water molecules that dissociate at lower altitudes. These light atoms are most susceptible to escape and are therefore a key element to study in the analyses of water escape from Mars. To date, the Mars Atmosphere and Volatile Evolution (MAVEN) mission has obtained the largest data set of high spectral resolution H Lyman-α emission brightness measurements from the martian upper atmosphere. This data set contains emissions that are unobstructed by contributions from H atoms in the interplanetary medium. In this presentation, seven years of continuous observations of the upper atmosphere of Mars are analyzed. The properties of H atoms (such as brightness and temperature), and their variability with solar illumination conditions, topography, seasons, local time, and solar activity are investigated and interpreted.