When liquid water flowed on Mars

And again the world speaks of water on Mars. Of course, we already know that there are sources of ice at the poles of the Red Planet; we know that about 2 percent of the Martian regolith consists of water (at the Martian science lab, at least); we also know that ancient Mars was a “wet” world, having rivers, lakes, and even seas — according to sedimentary rocks and minerals that could only be formed in copious amounts of liquid water.

But now NASA has found some pretty strong evidence that the seasonal short-term, dark channels seen on the steep slopes are formed by saline liquid water that is flowing, apparently, across the barren surface of Mars today.

Repetitive downlink

When liquid water flowed on Mars

Shown here is a 3-D map of the slopes of Gale Crater, which was created by observing a high-resolution science experiment camera (HiRISE) attached onboard a NASA Mars probe. Dark channels directed down the slopes are known as “repeating descending lines” and they could be another one of the greatest clues that some forms, at least of the main microbes, can use this water as a way of subsistence.

Evidence of seasonal water fall

When liquid water flowed on Mars

After arriving in orbit in 2006, the Martian orbital probe began an active campaign of observing high-resolution surfaces. In 2011, planetary scientists reported the formation of recurring descending lines, or RSL, in the southern hemisphere that existed from winter to summer. As the drops fall from the melting ice cream, so these dark features resemble the flow of liquid water on the surface of Mars. However, the find was not convincing.


When liquid water flowed on Mars

Missions to the surface of the Red Planet gradually formed a picture of chemicals in the soil of Mars, or regolith. Particularly noteworthy is the NASA's Phoenix landing module, which found evidence of living water droplets on the surface in 2008. However, liquid water would not be possible on Mars today; atmospheric pressure and temperature too low for storing liquid water; water exists in a solid (ice) or gaseous (vapor) state. Ice does not melt on the surface of Mars, it sublimates like ice of carbon dioxide (the so-called “dry ice”) at room temperature on Earth.

To the possibility of liquid water on the surface, “Phoenix” was added the possibility that the surface should be rich in highly toxic salts, known as perchlorates. When mixed with water, the freezing point of these salts is lower than that of water, which potentially allows liquid water to remain only under the surface, despite the cold conditions. Since then, NASA’s “Curiosity” Curiosity has also found evidence of perchlorates in the soil.

CRISM and HIRISE are combined

When liquid water flowed on Mars

Perchlorates have formed a key theme before the grand announcement on Monday. Using a different instrument on board a Martian orbital probe, a spectrometer called HIRISE (a compact-image spectrometer on a Martian probe) and using a new method of analysis, scientists were able to study the chemical composition of these dark channels. What they found was the chemical “signatures” of the hydrated salts - mainly the perchlorate residues left after the liquid water spikes, known as “brine”.

More questions than answers

When liquid water flowed on Mars

Although it is interesting that the source of these “brines”, apparently, feeding channels is something mysterious. Scientists point to the possibility of seasonal melting under the surface of the ice, or possibly moisture from the atmosphere, somehow condensing into water, but none of the explanations are satisfactory.

Not available for robot

When liquid water flowed on Mars

This may be powerful evidence of liquid water on the surface of Mars, but scientists do not see this “pickle” as a sign of life in the sense in which we understand life. Too high salinity in the RSL would be for microbes a struggle for survival without evolution. But on Earth, despite its toxicity, some microbes use perchlorate salts as the energy of the sun.

The location of these potential sources of life makes it difficult for us to send an expedition of robots to check them. Despite the fact that some researchers hope that “Curiosity” will find “Rossol” on the slopes of Ostroi Mountains in Gail crater, the best way to study them is from orbit. But it will be very good if we can send a human expedition to the Red Planet to check everything.

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