Data from the Hubble and the MAVEN probe helped Russian and foreign scientists find out where the water from the Mars atmosphere disappears and how the Sun is involved in its disappearance. Their findings were published in the journal Geophysical Research Letters.
In recent years, scientists have found many hints that rivers, lakes and whole oceans of water existed on the surface of Mars in ancient times, containing almost as much liquid as our Arctic Ocean. On the other hand, some planetary scientists believe that even in ancient times, Mars could be too cold for the permanent existence of oceans, and its water could be in a liquid state only during volcanic eruptions.
Recent observations of Mars with ground-based telescopes have shown that over the past 3.7 billion years, Mars has lost an entire ocean of water, which would be enough to cover the entire surface of the red planet with an ocean 140 meters thick. Where this water disappeared, scientists are trying to find out today.
Today, two Martian vehicles are trying to solve this riddle at once - the American MAVEN probe, which reached the orbit of Mars five years ago, and the Russian-European apparatus "ExoMars-TGO", which has been studying the atmosphere of the red planet for more than a year.
When the first spacecraft arrived at the planet, as noted by Shaposhnikov and his colleagues, he almost immediately discovered several strange phenomena that did not fit into the generally accepted ideas about the structure and behavior of the air shell of Mars.
In particular, MAVEN sensors detected large amounts of hydrogen and other traces of water in the upper atmosphere of the planet, where scientists did not expect to see them, and recorded sharp changes in their concentration during the onset of summer and winter. This was also a big surprise for planetary scientists, who believed that water "escapes" from Mars at a uniform speed.
Both of these discoveries posed a question for scientists - how does water, which is present in all layers of the planet's atmosphere in minimal quantities, enter the upper layers of its atmosphere, and what processes can enhance or slow down its inflow?
The problem is that Mars' air layer is so rarefied that water in it can almost always exist only in the form of microscopic ice crystals. Despite their small size, they will be too heavy for the weak Martian air currents to lift and to an altitude of more than 60 kilometers, where MAVEN sensors recorded large amounts of hydrogen.
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Shaposhnikov and his colleagues figured out how this happens, drawing attention to the fact that the maximum amounts of water in the upper atmosphere of Mars appeared there during the summer solstice in the southern hemisphere and during dust storms. They linked this unusual phenomenon to one unique feature of Mars, not typical of Earth or Venus, but reminiscent of the ebb and flow of the moon.
The gravitational interactions between our planet and its companion, as the researchers explain, affect not only the oceans of the Earth, but also its atmosphere, causing its air shells to contract and stretch when approaching the Moon and moving away from it.
Something similar happens in the atmosphere of Mars, where the main "conductor" of such changes is not Phobos and Deimos, which are too small for this, but the Sun, which directly "stretches" the air envelopes of the red planet.
The closer Mars approaches the star, the stronger it acts on its atmosphere, helping the clouds of ice crystals rise to great heights in the circumpolar regions of the planet, where the ascending air currents move especially rapidly.
This process is sharply intensified during dust storms, as dust particles help sunlight to heat the atmosphere of Mars more strongly, and water - to condense and form small ice crystals that can "fly up" to more impressive heights.
Using these ideas, scientists created a new climate model for Mars, which took into account the influence of the Sun and dust on the water cycle in the atmosphere. They tested her predictions using data from the MRO probe obtained in 2007-2009 during the observation of a powerful dust storm.
