An international team led by scientists from the University of Liège has observed, for the first time in the visible range, a glow on the night side of the planet Mars. These new observations provide a better understanding of the dynamics of the upper atmosphere of the Red Planet and its variations throughout the year.
A scientific team led by researchers from the Laboratory for Planetary and Atmospheric Physics (LPAP) at the University of Liège (BE) has just observed, for the first time, lights in the night sky over Mars using the UVIS-NOMAD instrument on board the Trace Gas Orbiter (TGO) satellite of the European Space Agency (ESA). This instrument is part of the NOMAD spectrometer suite developed at the Royal Institute for Space Aeronomy in Uccle, and tested and calibrated at the Liège Space Centre. It was inserted into circular Martian orbit at an altitude of 400 km in 2008.
Initially designed to map the ozone layer surrounding the planet in the ultraviolet, UVIS-NOMAD covers a spectral range extending from the near ultraviolet to red. For this purpose, the instrument is usually oriented towards the centre of the planet and observes sunlight reflected by the planetary surface and atmosphere. Based on a proposal from our laboratory, the instrument was oriented towards the limb of the planet in order to observe its atmosphere from the edge,” explains Jean-Claude Gérard, planetologist at ULiège. Back in 2020, we were already able to detect the presence of a green emission between 40 and 150 km in altitude, present during the Martian day. This was due to the dissociation of the CO2 molecule, the main constituent of the atmosphere, by ultraviolet solar radiation.”
A long journey for oxygen atoms
The TGO satellite, when observing the atmosphere at night, has just detected a new emission between 40 and 70 km altitude. This emission is due to the recombination of oxygen atoms created in the summer atmosphere and carried by the winds towards the high winter…