The small red planet is losing water more quickly than what theory, as well as past observations, would suggest.
The gradual disappearance of water (H2O) occurs in the upper atmosphere of Mars: sunlight and chemistry disassociate water molecules into hydrogen and oxygen atoms that the weak gravity of Mars cannot prevent from escaping into space.
An international research team, led partly by CNRS researcher Franck Montmessin, has just revealed that water vapor is accumulating in large quantities and unexpected proportions at an altitude of over 80 km (50 mi) in the Martian atmosphere. Measurements showed that large atmospheric pockets are even in a state of supersaturation, with the atmosphere containing 10 to 100 times more water vapor than its temperature should theoretically allow.
With the observed supersaturation rates, the capacity of water to escape would greatly increase during certain seasons. These results, which were published in Science on 9 January 2020, were obtained thanks to the Trace Gas Orbiter probe from the ExoMars mission, financed by the European Space Agency and the Russian space agency Roscosmos.
Reference: “Stormy water on Mars: The distribution and saturation of atmospheric water during the dusty season” by Anna A. Fedorova, Franck Montmessin, Oleg Korablev, Mikhail Luginin, Alexander Trokhimovskiy, Denis A. Belyaev, Nikolay I. Ignatiev, Franck Lefèvre, Juan Alday, Patrick G. J. Irwin, Kevin S. Olsen, Jean-Loup Bertaux, Ehouarn Millour, Anni Määttänen, Alexey Shakun, Alexey V. Grigoriev, Andrey Patrakeev, Svyatoslav Korsa, Nikita Kokonkov, Lucio Baggio, Francois Forget and Colin F. Wilson, 17 January 2020, Science.
In France this research involved scientists from the Laboratoire atmosphères, milieux, observations spatiales (CNRS/Université de Versailles Saint-Quentin-en-Yvelines/Sorbonne Université) and the Laboratoire de météorologie dynamique (CNRS/École polytechnique/ENS Paris/Sorbonne Université).