Water heavily fractionated as it ascends on Mars as revealed by ExoMars/NOMAD
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Isotopic ratios and, in particular, the water D/H ratio are powerful tracers of the evolution and transport of water on Mars. From measurements performed with ExoMars/NOMAD, we observe marked and rapid variability of the D/H along altitude on Mars and across the whole planet. The observations (from April 2018 to April 2019) sample a broad range of events on Mars, including a global dust storm, the evolution of water released from the southern polar cap during southern summer, the equinox phases, and a short but intense regional dust storm. In three instances, we observe water at very high altitudes (>80 km), the prime region where water is photodissociated and starts its escape to space. Rayleigh distillation appears the be the driving force affecting the D/H in many cases, yet in some instances, the exchange of water reservoirs with distinctive D/H could be responsible.
CitationVillanueva, G.L.; Liuzzi, G.; Crismani, M.M.J.; Aoki, S.; Vandaele, A.C.; Daerden, F.; Smith, M.D.; Mumma, M.J.; Knutsen, E.W.; Neary, L.; Viscardy, S.; Thomas, I.R.; Lopez-Valverde, M.A.; Ristic, B.; Patel, M.R.; Holmes, J.A.; Bellucci, G.; Lopez-Moreno, J.J. (2021). Water heavily fractionated as it ascends on Mars as revealed by ExoMars/NOMAD. , Science Advances, Vol. 7, Issue 7, eabc8843, DOI: 10.1126/sciadv.abc8843.