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Abstract :
[en] The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission's Imaging Ultraviolet Spectrograph (IUVS) observes Mars in the far and mid ultraviolet (110-340 nm), investigating lower and upper atmospheric structure and indirectly probing neutral atmospheric escape. The instrument is among the most powerful spectrographs sent to another planet, with several key capabilities: separate Far-UV & Mid-UV channels for stray light control; a high-resolution echelle mode to resolve deuterium and hydrogen emission; internal instrument pointing and scanning capabilities to allow complete mapping and nearly continuous operation; and optimization for airglow studies. After two Earth years in orbit (one Mars year), IUVS has assembled a large quantity of data and provided insights on present-day processes at Mars including dayglow, nightglow, aurora, meteor showers, clouds, and solar-planetary interactions. In this presentation, we will highlight several new discoveries made by IUVS. Among the key results obtained by IUVS are: (1) discovery of the widespread occurrence of a diffuse proton aurora representing a previously unknown source of energy deposition into the atmospheres of unmagnetized planets; (2) first spatial mapping of nitric oxide nightglow reveals regions of atmospheric downwelling necessitating substantial changes to global atmospheric circulation models; (3) a new high-spatial-resolution UV imaging mode allows detection of clouds from nadir to limb and their local time evolution, as well as unprecedented determinations of Mars’ low-altitude ozone; (4) discovery of a persistent meteoric metal layer in Martian atmosphere; (5) atmospheric structure, composition and dynamics from stellar occultation. We will present an overview of these results and a discussion of their implications for characterizing the state of the atmosphere and its evolution.
