Water on Mars, NASA's announcement


What is the nature of the dark and even tens and tens of meters long languages ​​that form and descend from the edges of numerous Mars craters during the hottest periods of the year on the Red Planet?

This is one of the enigmas of Mars, and was finally solved by Lujendra Ojha, of the Georgia Institute of Technology in Atlanta (USA): because of the importance of the study (published in Nature Geoscience), NASA convened a press conference during the which details were explained.

Since the phenomenon was first observed and then continuously monitored by the probes around Mars, there have been more than one hypothesis to explain it: among these, one of the most accredited interpreted the dark stripes as the result of spills of water from the edges of the craters. But the orbital instruments do not have the capacity to investigate in those narrow dark bands, no wider than 5 meters, and therefore a certain answer has always been lacking.

Salts and water. Lujendra Ojha has developed a methodology to study the spectrum, or the chemical composition, of a single pixel of the images coming from Mars, and in this way has shown that to make those languages ​​dark the sand is the presence of salt water.

Now we have the certainty that water exists on Mars, just below the surface, in different points of the planet

Image Dark stripes whose formation is linked to the presence of water (and salts) that come out during the hot season. | Nasa

The researcher explains: "The analysis of the sands near the dark tongues do not show the presence of salts, and therefore they come out together with the water: it is magnesium perchlorate, also found where the rasa of NASA Curiosity, of chlorate, is working. of magnesium and sodium perchlorate ".

The next puzzle to be solved:

The answer on the origin of seasonal water flows may not be easy to find. It can be related to the presence of ice that, during the Martian summer, when the temperature increases, it melts and escapes in jets, and then evaporates quickly. It is a plausible hypothesis: it is not necessary for the temperature to exceed zero degrees Celsius to have liquid water, because the presence of some salts can bring the liquefaction temperature even to -190 ° C. And in certain regions of the planet the summer temperature can exceed even 15 ° C.

Image Another image showing dark stripes produced by the release of salt water from the edges of Horowitz crater. | Nasa

But this hypothesis could apply to water spills in regions close to the poles, as it is difficult for there to be ice in abundance even near the equator, where many "streaks" have been observed, although in some equatorial regions it has been ice presence detected through radar analysis.

To explain the equatorial ice, the hypothesis has been advanced that there may be real aquifers there that with the increase of temperature produce puffs, like geysers. And last but not least the hypothesis that water derives from the condensation of atmospheric water vapor which, after having penetrated into the ground, then returns to the atmosphere has also been advanced.

Image These dark stripes are about 100 meters long and are located near the Horowitz crater. | Nasa

At the moment, based on what we know it may also be that there is no single answer, but instead there are several valid explanations for the presence of water in the different areas of Mars.

Whatever the explanation:

For the benefit of man. There can be no rivers or lakes, because the low pressure of the Martian atmosphere makes it just evaporate on the surface, but knowing that there is ice and, even better, groundwater, is a nice starting point for the first human base on the Planet Red.

Enrico Flamini, scientific coordinator of the Italian Space Agency (ASI), explained that "it is the first evidence that demonstrates the existence of a water cycle on the surface of Mars".

Image This is the footprint of water on the west side of Chasma Coprates, in the equatorial region of Mars. | Nasa

See also