Transient HCl in the atmosphere of Mars

Oleg Korablev (1) , Kevin Olsen (2) , Alexander Trokhimovskiy (1) , Franck Lefèvre (3) , Franck Montmessin (3) , Anna A. Fedorova (1) , Michael J. Toplis (4) , Juan Alday (2) , Denis A. Belyaev (1) , Andrey Patrakeev (1) , Nikolay I. Ignatiev (1) , Alexey V. Shakun (1) , Alexey V. Grigoriev (1) , Lucio Baggio (5) , Abdanour Irbah (5) , Gaetan Lacombe (3) , Yuri S. Ivanov (6) , Shohei Aoki (7, 8) , Ian R. Thomas (8) , Frank Daerden (8) , Bojan Ristic (8) , Justin T. Erwin (8) , Manish Patel (9) , Giancarlo Bellucci (10) , Jose-Juan Lopez-Moreno (11) , Ann C. Vandaele (8)

1 IKI - Space Research Institute of the Russian Academy of Sciences
2 Department of Physics [Oxford]
3 PLANETO - LATMOS
4 IRAP - Institut de recherche en astrophysique et planétologie
5 LATMOS - Laboratoire Atmosphères, Milieux, Observations Spatiales
6 MAO - Main Astronomical Observatory of NAS of Ukraine
7 LPAP - Laboratoire de Physique Atmosphérique et Planétaire
8 BIRA-IASB - Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique
9 OU - The Open University [Milton Keynes]
10 IAPS - Istituto di Astrofisica e Planetologia Spaziali - INAF
11 IAA - Instituto de Astrofísica de Andalucía

A major quest in Mars’ exploration has been the hunt for atmospheric gases, potentially unveiling ongoing activ- ity of geophysical or biological origin. Here, we report the first detection of a halogen gas, HCl, which could, in theory, originate from contemporary volcanic degassing or chlorine released from gas-solid reactions. Our de- tections made at ~3.2 to 3.8 m with the Atmospheric Chemistry Suite and confirmed with Nadir and Occultation for Mars Discovery instruments onboard the ExoMars Trace Gas Orbiter, reveal widely distributed HCl in the 1- to 4-ppbv range, 20 times greater than previously reported upper limits. HCl increased during the 2018 global dust storm and declined soon after its end, pointing to the exchange between the dust and the atmosphere. Under- standing the origin and variability of HCl shall constitute a major advance in our appraisal of martian geo- and photochemistry.

Domains: Sciences of the Universe [physics]

Oleg Korablev, Kevin Olsen, Alexander Trokhimovskiy, Franck Lefèvre, Franck Montmessin, et al.. Transient HCl in the atmosphere of Mars. Science Advances , 2021, 7 (7), pp.EABE4386. ⟨10.1126/sciadv.abe4386⟩. ⟨insu-03140676⟩