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Water heavily fractionated as it ascends on Mars as revealed by ExoMars/NOMAD

Vandaele, Ann Carine; Aoki, Shohei; Liuzzi, Giuliano +15 more

Transient HCl in the atmosphere of Mars

Montmessin, Franck; Belyaev, Denis A.; Fedorova, Anna A. +23 more

A major quest in Mars' exploration has been the hunt for atmospheric gases, potentially unveiling ongoing activity 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 detections made …

Morphological and Spectral Diversity of the Clay-Bearing Unit at the ExoMars Landing Site Oxia Planum

Pan, Lu; Quantin-Nataf, Cathy; Cremonese, Gabriele +10 more

The European Space Agency and Roscosmos' ExoMars rover mission, which is planned to land in the Oxia Planum region, will be dedicated to exobiology studies at the surface and subsurface of Mars. Oxia Planum is a clay-bearing site that has preserved evidence of long-term interaction with water during the Noachian era. Fe/Mg-rich phyllosilicates hav…

The vertical structure of CO in the Martian atmosphere from the ExoMars Trace Gas Orbiter

Forget, F.; Montmessin, F.; Korablev, O. +11 more

Carbon monoxide (CO) is the main product of CO₂ photolysis in the Martian atmosphere. Production of CO is balanced by its loss reaction with OH, which recycles CO into CO₂. CO is therefore a sensitive tracer of the OH-catalysed chemistry that contributes to the stability of CO₂ in the atmosphere of Mars. To date, C…

Isotopic fractionation of water and its photolytic products in the atmosphere of Mars

Montmessin, Franck; Belyaev, Denis A.; Fedorova, Anna A. +13 more

The current Martian atmosphere is about five times more enriched in deuterium than Earth's, providing direct testimony that Mars hosted vastly more water in its early youth than nowadays. Estimates of the total amount of water lost to space from the current mean D/H value depend on a rigorous appraisal of the relative escape between deuterated and…

Revealing a High Water Abundance in the Upper Mesosphere of Mars With ACS Onboard TGO

Montmessin, Franck; Belyaev, Denis A.; Fedorova, Anna A. +7 more

We present the first water vapor profiles encompassing the upper mesosphere of Mars, 100-120 km, far exceeding the maximum altitudes where remote sensing has been able to observe water to date. Our results are based on solar occultation measurements by Atmospheric Chemistry Suite (ACS) onboard the ExoMars Trace Gas Orbiter (TGO). The observed wave…

Seasonal reappearance of HCl in the atmosphere of Mars during the Mars year 35 dusty season

Forget, F.; Montmessin, F.; Irwin, P. G. J. +15 more

Hydrogen chloride was discovered in the atmosphere of Mars for the first time during the global dust storm in Mars year (MY) 34 (July 2018) using the Atmospheric Chemistry Suite mid-infrared channel (ACS MIR) on the ExoMars Trace Gas Orbiter. The simultaneity of variations in dust and HCl, and a correlation between water vapour and HCl, led to the…

Day-night differences in Mars methane suggest nighttime containment at Gale crater

Atreya, Sushil K.; Vasavada, Ashwin R.; Moores, John E. +10 more

We report new measurements of atmospheric methane by the Curiosity rover's Tunable Laser Spectrometer that is part of the Sample Analysis at Mars suite (TLS-SAM), finding nondetections during two daytime measurements of average value 0.05 ± 0.22 ppbv (95% confidence interval CI). These are in marked contrast with nighttime background levels of 0.5…

Comprehensive investigation of Mars methane and organics with ExoMars/NOMAD

Vandaele, Ann Carine; Aoki, Shohei; Liuzzi, Giuliano +17 more

Methane (CH₄) on Mars has attracted a great deal of attention since it was first detected in January 2003. As methane is considered a potential marker for past/present biological or geological activity, any possible detection would require evidence with strong statistical significance. Ethane (C₂H₆) and ethylene (C…

A stringent upper limit of 20 pptv for methane on Mars and constraints on its dispersion outside Gale crater

Daerden, F.; Forget, F.; Montmessin, F. +17 more

Context. Reports on the detection of methane in the Martian atmosphere have motivated numerous studies aiming to confirm or explain its presence on a planet where it might imply a biogenic or more likely a geophysical origin.
Aims: Our intent is to complement and improve on the previously reported detection attempts by the Atmospheric Chemist…