Origins of the Martian aurora observed by Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars (SPICAM) on board Mars Express

François Leblanc (1) , Olivier Witasse (2) , J. Winningham (3) , D. Brain (4) , Jean Lilensten (5) , P.-L. Blelly (6) , R. A. Frahm (3) , Jasper S. Halekas (4) , Jean-Loup Bertaux (1)

1 SA - Service d'aéronomie
2 RSSD - Research and Scientific Support Department, ESTEC
3 Space Science and Engineering Division [San Antonio]
4 SSL - Space Sciences Laboratory [Berkeley]
5 LPG - Laboratoire de Planétologie de Grenoble
6 LPCE - Laboratoire de physique et chimie de l'environnement

On the 11 August 2004, the UV spectrograph Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars (SPICAM) on board Mars Express made the first observation of auroral-type emission on the Martian nightside. In this paper, we describe the results of a new analysis of the observed emission owing to a better calibration of SPICAM UV channel and the use of all spectral information obtained during this observation. Several possibilities for the origin of this emission are discussed. We discussed, in particular, the possible exact geometry of the observation and the possible origins of the Martian aurorae. The emissions measured by SPICAM ultraviolet spectrometer have most probably been produced by electrons with an energy distribution peaking at few tens of eV rather than by electron distributions peaking above 100 eV.

Keywords: IONOSPHERE; CARBON-DIOXIDE; PLASMA ACCELERATION; IONIZATION; SPECTROMETER; AIRGLOW; MAGNETIC-FIELD; FLUXES; RATES

Domains: Sciences of the Universe [physics]

François Leblanc, Olivier Witasse, J. Winningham, D. Brain, Jean Lilensten, et al.. Origins of the Martian aurora observed by Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars (SPICAM) on board Mars Express. Journal of Geophysical Research Space Physics, 2006, 111 (A9), A09313 (9 p.). ⟨10.1029/2006JA011763⟩. ⟨insu-00357254⟩