Mars did not look like Earth in the early years of its life, but like Tatooine from Star Wars or any other desert planets from books and films, where water is, but it is not enough, scientists write in an article published in the journal Nature Geoscience.
“Many of our colleagues adhere to the theory of a 'dry and cold' Mars for the reason that it would be extremely difficult to warm it up to the required temperatures using the greenhouse effect, given the low brightness of the Sun at that time. Models and current geological data on Mars, in turn, indicate that it was a semi-arid climate,”write Ramses Ramirez and of the Tokyo Institute of Technology, Japan and colleagues.
In recent years, scientists have found many hints that rivers, lakes and entire oceans of water existed on the surface of Mars in ancient times, containing almost as much liquid as the 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 the oceans, and its water could be in liquid form 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 today are trying to figure out by studying ancient Martian meteorites.
Ramirez and his colleague Robert Craddock of the Smithsonian Institution in Washington, USA, found a solution to all these problems by analyzing how much early Mars could warm up with large and small amounts of ice on its surface.
As the scientists explain, the main drawback of their colleagues is that they have always assumed that Mars had large reserves of water ice that covered almost the entire surface of the planet. Craddock and Ramirez decided to test what would happen if these ice reserves were reduced to the minimum acceptable level that would not contradict the observations of probes and the Curiosity rover.
Their calculations showed that under such conditions Mars will be a sufficiently warm planet on which water can exist in liquid or vapor form at the equator and in the tropics even in the first epochs of the life of the solar system, when the Sun was one third dimmer than today.
On the other hand, there was not enough water on such a "wet and warm" Mars. Typical rainfall in its wettest regions did not exceed 100-200 millimeters per year, which turned them into analogs of terrestrial semi-deserts and arid regions like the Sahel, the "dressing room" of the Sahara.
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Nevertheless, Ramirez and Craddock suggest that this amount of rain was enough, especially during intense volcanic eruptions, which melted additional portions of ice, to form temporary or even permanent rivers, lakes and other water flows, whose traces can be seen on Mars today. …
When the atmosphere of Mars began to evaporate into space, water followed along with it, and today, if the new theory of planetary scientists is close to truth, there is almost no water left on the red planet in any form. Scientists hope that subsequent launches of rovers and manned expeditions will help test whether this is actually the case.
