Ar non-thermal component as seen by MAVEN after 4 years of observations?

Abstract

International audienceThe dissociative recombination of O2+ in Mars' ionosphere is thought to be today major channel of Mars' neutral atomic oxygen escape to space. In Leblanc et al. (2018), we showed that the exospheric Ar can be measured by NGIMS/MAVEN up to 1200 km in altitude, highlighting the dichotomy of this exospheric population and the existence of a significant non-thermal component. Its main origin was shown to be the collisional interaction between the atmospheric Ar and the products of the dissociative recombination of the O2+ ions. We here present the whole set of NGIMS measurements of the atmospheric and exospheric Ar obtained so far