Discrete Aurora on Mars: Insights Into Their Distribution and Activity From MAVEN/IUVS Observations

Mars Atmosphere and Volatile Evolution (MAVEN)'s Imaging Ultraviolet Spectrograph has identified 278 occurrences of discrete aurora events on Mars, which are patchy, sporadic ultraviolet emissions emanating from the upper atmosphere. We confirm prior results finding that emissions are highly correlated with crustal magnetic fields results, with the brightest and most frequent occurrences located around strong crustal fields in the southern hemisphere. The six-year data set shows that events can also occur globally, in regions of weak or absent crustal fields. We find that events occur primarily in evening hours, especially during favorable orientations of the interplanetary magnetic field. Under these conditions, auroral events probably occur nightly and last for hours. Optical counterparts to these UV emissions would probably be detectable with present-day instrumentation, and would be visible to future astronauts.