Until recently discovered on Mars clay was considered a sure sign of the fact that on the red planet has or, at least once existed water. However, new research conducted by Alain Meunier from the University of Poitiers (France), shows that clay layers can specify only on the processes of volcanic activity.

Some models are ancient Mars is dry and cold, and others - warm and wet, in fact, the climate of the planet in a distant era, most likely, was wet and rather cold, close to the circumpolar on Earth. This is consistent with all recently discovered geological characteristics.

The presence of deposits of clay with a high content of water molecules found in the second half of 2000-ies probe Mars Reconnaissance Orbiter (MRO), initially inspired scientists hope that in ancient times on Mars could support life. This could happen in the so-called Noah's period (about 3.8-3.5 billion years ago). Astrogeology suggested that clay layers belonging to that era, could be formed either as a result of interaction of soil with water of seas, rivers and oceans, located on the surface of the planet, either due to supply water to the surface from the bowels through hydrothermal vents. On the Ground of such quantity of liquid water would be enough for the emergence of microorganisms.

Scientists believe that over a given period on Mars could be a water in a liquid state. Volcanoes melted the ice below the surface of the planet, and water flowed out. Some time later she began to evaporate, as evidenced found on the planet compounds sulphates.

In 2004 orbital probe "Mars Odyssey" found under the surface of the planet deposits of water ice. And in 2008 probe Phoenix", landing near the North pole, was able to extract water from the Martian soil. After that, the question of the existence of water on Mars was finally resolved.

Researchers believe that over the past 3.5 billion years of the Martian climate is not changed, remaining cool and dry. However, from time to time on the surface of the planet there is a small lake, when geothermal heat melts the ice and from the Martian subsurface water breaks or outdoor glacier falls meteorite...

Meanwhile, the Martian minerals contained in recorded to the red planet to Earth meteorites are very similar in chemical composition of the clay from the Pacific Atoll of Mururoa, located in French Polynesia, which was formed at cooling plentiful water and lava. Perhaps the guests from Mars have a similar origin. Moreover, the thickness of ancient Martian clay reaches a few hundred meters, so, most likely, they were formed by lava.

"If the devices Curiosity confirm this theory, then it will be impossible to exclude, that on Mars there was never any significant amounts of water", stated the authors of the study.

One more indirect evidence of the theory may be the fact that last year on the territory of the Pyrenees (Spain) were found deposits of so-called travertine, which presumably exist on Mars.

Usually, such deposits are formed by water, saturated dioxide of lime, often near the plants growing near water source. At the exit of fresh underground water on the soil surface limy tufa postponed unevenly, in the form of hills and cascades. On Earth such geological structures appeared more than 250 thousand years ago due to karst springs.

Scientists have already paid attention to the similarity of the karst hills with extinct Martian volcanoes. So, Alexis Rodriguez from the Institute of planetary Sciences in Tucson (Arizona) suggests that Mars once had been a similar geological processes with participation of water, and at a much larger scale than on Earth...

However, to say anything for sure yet. In order to obtain reliable results, it is necessary to analyze the soil in place through a powerful microscope. The Rover Curiosity, unfortunately, is not equipped by the equipment of a similar capacity. You can also try to deliver to Earth certain rare-earth elements.

And yet the hope that once on Mars was a "real" water in the seas and rivers, remains. So, morphological peculiarities Gale crater, where now is Curiosity, indicate that it had located the lake, and not the volcano...