Scientists have found that some of the components found in the Martian soil can destroy entire bacterial cultures in just a few minutes. Researchers wondered for a long time whether microorganisms would be able to survive on the surface of the Red Planet. And the results of the latest laboratory tests show that the fate of any green bacteria that hit the surface of Mars will be unenviable. Apparently, growing potatoes on Mars will be much more difficult than previously thought.
The problem lies in perchlorates - chlorine-containing chemicals first discovered on Mars in 2008. These substances are able to keep water on Mars in a liquid state, but in fact turn it into an acidic brine. Perchlorates are toxic to humans, but they don't necessarily pose the same problems for microbes. And since these compounds allow water to be in liquid form, scientists previously believed that their presence on Mars could be beneficial for life.
However, researchers from the University of Edinburgh say that exposure to strong ultraviolet light on these compounds turns them into a deadly poison for absolutely all life forms.
"Perchlorates remain stable at room temperature, but become a powerful oxidant when activated, for example, at high temperatures," the researchers report.
One way to convert perchlorate to acid is by exposing it to a powerful source of ultraviolet radiation. Since Mars is much less dense than Earth's atmosphere, its surface is exposed to this type of radiation every day.
Scientists decided to conduct an experiment. They took the bacterium Bacillus subtilis (Hay bacillus) found on the skin of spacecraft (including the ISS) and placed it in conditions that artificially recreate the environment on the surface of Mars. The bacteria floated in a solution of magnesium perchlorate of the same concentration found on the Red Planet, and then they were exposed to ultraviolet radiation of the same wavelengths that bombard the Martian surface. As a result, no bacteria survived. Death occurred within only 30 seconds.
To test the experiment, the researchers also exposed bacteria to ultraviolet light that were not placed in a perchlorate medium. Even so, the entire colony was destroyed within just 1 minute.
Of course, the surface of Mars is not as wet as the bottom of a Petri dish. Therefore, scientists decided to conduct a similar experiment by placing the bacterium in drier conditions - silicon dioxide. This environment made the bacteria Bacillus subtilis a little easier to survive, but in the end most of them died anyway. From this we can conclude that if life exists on Mars, then, most likely, it is hidden deep under the surface of the planet, where the concentration of perchlorates is much lower.
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“Despite earlier suspicions of toxic effects caused by acids on the Martian surface, our observations show that the environment on the surface of modern Mars is even more hostile to living cells and is an explosive cocktail of acids, iron oxide, perchlorate and ultraviolet radiation,”the scientists say.
If the salt streams descending from the Martian rocks are indeed concentrated streams of perchlorates, then such an environment is clearly unsuitable for supporting life. And since perchlorates are present on almost the entire surface of the Martian soil, then, based on the findings of the team of researchers, we can sadly state that most of the planet's surface is uninhabited.
But there is also some positive news in this. If the Martian surface is able to kill all terrestrial microbes on contact, then for the planet itself it will represent an excellent protective agent - there is less chance that in future missions we will be able to bring our terrestrial microbes there.
Scientists, in turn, are going to continue their research and find out how exactly such a deadly cocktail on the Martian surface kills living cells.
NIKOLAY KHIZHNYAK