Long-lived auroral structures and atmospheric losses through auroral flux tubes on Mars

Abstract

The ASPERA-3 observations of electron and ion fluxes over the regions dominated by crustal magnetic fields show the existence of long-lived and active aurora-type magnetic flux tubes with a width of 20-150 km. The activity manifests itself by large electron energy fluxes (≥10^-4 W/m²) and strong distortions in the upper (350-400 km) ionosphere. In some events the peaked electron energy distributions typical for Earth aurora are so pronounced that they are present in velocity distribution functions. A significant depletion of such auroral flux tubes is accompanied by the appearance of oxygen beams and a heating of the ions of ionospheric origin. Auroral activity was observed on several subsequent orbits of the Mars Express spacecraft during more than two weeks implying a stable existence of aurora on Mars. Atmospheric loss driven by energy deposition in the auroral flux tubes is estimated as ∼10²³ s^-1.