Analysis of data collected by the European Space Agency?'s Mars Express? spacecraft leaves no room for doubt: the Martian atmosphere of contains water vapor in a supersaturated state. This surprising finding will enable scientists to better understand the water cycle on Mars, as well as the evolution of its atmosphere.
The research was led by a team from the Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS, CNRS / UPMC / UVSQ), in collaboration with Russian and French colleagues(1), and received support from CNES. It is published in Sept. 30, 2011 issue of the journal Science.
On Earth, water vapor tends to condense, i.e. turn into a liquid, when the temperature falls below dew point. The atmosphere is said to be 'saturated' since it cannot hold any more moisture at that temperature and pressure. The excess water vapor then condenses around suspended particles and dust, forming precipitation. However, condensation may sometimes be much slower, especially when particles and dust are scarce. Unable to condense, the excess water vapor therefore remains in the gaseous state: this is known as supersaturation. Until now, it was assumed that this phenomenon could not occur in the Martian atmosphere, although this had never been proved.
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