Even in the most extreme environments of our planet, microorganisms are believed to exist and thrive everywhere, from the depths of the oceans to Mount Everest. However, in recent years scientists have discovered Two places on earth It is assumed that there is no life there.
The first was found in Antarctica In June, in a desert area Glacier ShackletonResearchers have discovered a series of conditions that prevent microorganisms from settling: Severe cold, dry soil and presence of toxic salts.
According to experts, the combination of these three factors limits the chances of improving life. Of the more than 200 soil samples taken from glaciers, No signs of life were found.
“It is always assumed that microorganisms are resistant and can live anywhere”, Indian Noah Fierre, a microbiological ecologist at the University of Colorado at Boulder, and his team studied soil in Antarctica.
How to take samples on Mars
This finding, Published by In the journal JGR Biosciences in May, will help guide Search for life on Mars, Because the soil in Antarctica is frozen, saturated with toxic salts, and has not accumulated significant amounts of liquid water for at least two million years like the soil on Mars.
Samples were taken in January 2018 during an expedition to remote areas of the Transantarctic Mountains. Scientists camped on the Shackleton Glacier and used a helicopter to collect it, raising it to more than 2,000 meters above sea level.
Byron Adams, biologist and project director at Brigham Young University Remember At the time of sample collection, the soil was Filled with volcanic rocks Perforated and bright red with centuries of wind erosion.
When scientists studied the rocks, they found that their bottoms were covered with toxic crystals of white salts, especially perchlorates, chlorates and nitrates. Perchlorates and chlorates are reactive, and the caustic salts used in rocket fuels and industrial lines are abundant on the surface of Mars.
“Obviously, we argue for using such places to study what Mars or anywhere else in the universe looks like.” Firmly Adams. If there are creatures that can live here and manage this environment, “then Maybe they can live on a planet like MarsHe added.
In 2019, a team of French-Spanish scientists had already suggested that there are places on earth where no kind of life can grow.
In an article Published by In the journal Nature Ecology & Evolution, the researchers concluded Dalol Geothermal ComplexThere is no trace of microbial life in one of the most dangerous and uninhabitable environments on our planet, located in the Danakil Desert (Ethiopia).
Between 2016 and 2018, experts collected numerous samples in four different areas of the geothermal complex. Red herring Most are related to laboratory pollution, while others may be bacteria introduced by humans during explorations and tourist visits to the site.
“After analyzing more samples than previous works, we tested them with adequate controls and a well – calibrated method to prevent contamination. These hot, salty, hyperacid pools are free of microorganisms, And nearby magnesium-laden saltwater lakes “, Underlined Purification Lopez Garcia, biologist and head of the work of the National Center for Scientific Research (CNRS).
The team recognized Two major physical and chemical barriers Prevents life from thriving in the presence of liquid water on earth and elsewhere.
The first obstacle is a High levels of magnesium, It has the ability to destroy any type of cell formation due to a phenomenon known as chyotropic activity. The second is consistent with A A lethal combination of hyper acidity and hypersalinity, Simultaneous molecular adjustments to very high and low pH are impossible.
The limit of life?
The authors of both studies try to be careful in their conclusions because there is a remote possibility that there are very few microorganisms in the samples and they have not been able to find any method.
“We can’t say the soil is sterile. No one can tell.”, He claimed Fear at the Shackleton Glacier. “It’s an endless search. There’s another method or variant of a method that can be tried,” he added.
The search also raises questions about how to interpret negative scientific results, especially in the search for life on other planets. The challenge returns to the philosophical question “How do you prove something negative?”.
Similarly, the evidence presented by the research team at Dalol Pools shows that there are places on the Earth’s surface. “It contains liquid water but it is sterile. “, As Underlined Lopez Garcia. This means the presence of liquid water on a planet, which is often used as a measure of habitat, not directly indicating that it has life.
Both studies allow Learn more about the limits of life on earth In addition, they need to be careful when interpreting mutant bio-signatures on and off the planet. This implies not believing in the apparent cellular or ‘biological’ aspect of a structure, as it may have an agiotic origin.
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