Atmospheric Chemistry Suite search for methane on Mars and its implications
Résumé
The ACS instrument onboard the ExoMars TGO has been developed to meet many relevant science goals, and especially measure trace presence of methane in the Martian atmosphere. Regular soundings in solar occultation mode started in March 2018. ACS have reported stringent upper limits all over the planet, which is not correlated with surface detections by MSL rover. With the methane lifetime of ~300 years, conventional chemistry cannot explain the disagreement. Gathering statistics and improvements in calibration on both sides didn't reveal any ways to align experimental datasets, at least an order of magnitude difference remains between MSL detections and firm ACS upper limits. The controversy in methane measurements led to the different hypotheses of previously unconsidered mechanisms of methane rapid destructions. In particular, recently discovered by ACS hydrogen chloride may be involved. In this work, we will present an up-to-date version of the ACS dataset, also implementing a zonal averaging approach to further increase methane upper limits and probe models predictions.