The Variability of D and H in the Upper Atmospheres of Mars: Implications for Water Escape
Résumé
The high-resolution echelle spectrograph on board the Mars Atmosphere and Volatile Evolution (MAVEN) mission has been observing resonantly scattered Lyman-a emissions from water-originating hydrogen (H) and deuterium (D) atoms in the upper atmosphere of Mars for almost three Mars Years. During this time, Mars encountered a close approach to a comet, severe space weather events, a planet encircling dust storm, and a relatively quiet solar cycle. The properties of D and H, derived from their UV emission brightness throughout MAVEN's lifetime, have been seen to vary due to these events as well as due to seasonal factors. At this time in the mission, adequate data coverage allows for comparative trendlines in the properties of D and H across the disk of Mars to be modeled and interpreted. The variability intrinsic to planet's orbit as well as due to external drivers are discussed along with implications for water escape over Mars' history.