On the steep slopes of craters and gorges on Mars, a suspicious phenomenon has been observed for years: every summer, numerous narrow dark stripes appear, running from top to bottom, and gradually lengthen. They disappear in the cold season. According to the main version, these are signs that liquid water still exists on the Red Planet. But the authors of a recent study strongly doubt this.

There is no doubt that rivers, lakes, seas and oceans existed on Mars billions of years ago. For example, many winding structures can be seen on the surface, which geologists instantly recognize as dried river beds. Clay minerals are found even on the Red Planet, and clay only forms in the presence of liquid water.

Where exactly the Martian hydrosphere went is a separate question: was it mostly lost in space or did it “go to the ground”, that is, buried in the structure of solid rocks. In any case, the Red Planet preserves a significant amount of water ice, not just in the polar caps: Satellite instruments have revealed that it is hidden under a layer of regolith in lower and even mid-latitudes.

In 2008, the Phoenix lander dug a small trench on the surface of Mars, and inside it, something white was visible under the red soil. When this whiteness partially disappeared after four days, NASA officially announced that the water ice had sublimated and immediately turned into a gaseous state.

Unfortunately, for the water on the surface of Mars to be liquid, the Red Planet needs a higher atmospheric pressure. However, with each long Martian year (lasting as much as 1.8 Earth years), planetary scientists observe interesting seasonal changes: in warm weather, narrow and long vertical stripes appear on slopes in the equatorial and mid-latitudes. Moreover, they are not there in winter. This is one of the important arguments in support of the version that these are water currents. Scientists hypothesize that groundwater may seep to the surface in this way in places.

According to researchers, Martian water should actually be a caustic salt water, that is, a highly concentrated salt solution. As you know, salt acts as antifreeze: with it, water is more resistant to cold and sometimes does not freeze even in severe frosts. In the case of Mars, the ideal type of salt for the “preparation” of such a non-freezing liquid is considered to be perchlorates – salts and esters of perchloric acid. Water with them does not freeze even at minus 75 degrees Celsius, and the average temperature on Mars is minus 58, sometimes close to plus 20.

By the way, the aforementioned “Phoenix” detected traces of perchlorate on the Red Planet. An even more interesting picture emerged when small round white structures were noticed on the support racks of this apparatus: there are strong suspicions that these are frozen drops of the same salt water. Recently all these facts and assumptions were summarized by researchers from the University of Arkansas and the Lunar and Planetary Institute in Houston (USA). They presented their findings in a paper for the journal Proceedings of the National Academy of Sciencesand these results were not very encouraging.

Scientists believe that there is very little perchlorate in the ice on Mars, so only a “microscopic” amount of the corresponding brine could form there. Also, according to the authors of the article, even if such a liquid existed, it would be very unsuitable for possible life on Mars: the so-called activity of water is very low – its “availability” to chemical reactions and biological processes.

Despite all this, planetary scientists emphasized that they do not consider liquid brines on Mars unrealistic, only a possible coincidence of sufficiently favorable conditions and the presence of the necessary salts could make them possible. Scientists concluded that seasonal bands on the slopes may be traces of sand and dust flows.