Acs Trace Gas Detection Attempts
A. Trokhimovskiy, A. A. Fedorova, O. I. Korablev, D. A. Belyaev, Space Research Institute Of The Russian Academy Of
Sciences (Iki Ras), Moscow, Russia (Trokh@Iki.Rssi.Ru), A. S. Braude, F. Montmessin, F. Lefèvre, Latmos/Ipsl, Uvsq
Université Paris-Saclay, Sorbonne Université, Cnrs, Guyancourt, France, J. Alday, Open University, Milton Keynes,
U.K., Kevin S. Olsen, Department Of Physics, University Of Oxford,Uk

Introduction: The Acs Instrument Onboard
Exomars Tgo Has Been Developed To Meet A Variety
Of Science Goals, In Particular, The Sensitive Search For
Trace Species In The Martian Atmosphere [1]. Regular
Soundings In Solar Occultation Mode Started In March
2018. For Methane Acs Reported Stringent 20 Ppt
Upper Limits All Over The Planet [2,3], Which Are Not
Correlated With Surface Measurements By The Msl
Rover [4]. With The Methane Lifetime Of ~300 Years,
Conventional Chemistry Cannot Explain The Disagreement. Acs Continues Regular Measurements To Gain
Statistics And In Hope For Possible Methane Spikes
Reported Previously [5]. The Presence Of Methane
Derivatives Like Ethane C2h6 Is Very Unlikely, Yet
Acs Sets An Improved Upper Limit Of 50 Ppt.