Bacterial spores can survive in the soils of Mars for over 280 million years

(ORDO NEWS) — Biologists have studied the effect of Martian temperatures and radiation on bacterial spores and concluded that microbes can lie dormant for more than 280 million years without losing viability when they are immersed in the soil to a depth of ten meters.

This raises the chances of discovering traces of life on Mars. The work was published in the journal Astrobiology. The results were announced on Tuesday by the press service of the American Northwestern University.

“Our study shows that the contamination of Mars with terrestrial bacteria, if it has already happened or will happen in the future, will be virtually eternal – it will last several tens of thousands of years.

This simultaneously increases the chances of the existence of life on Mars, but also significantly complicates the search for its traces.”,- said the professor of Northwestern University in Evanston (USA) Brian Hoffman, whose words are quoted by the press service of the university.

Over the past ten years, planetary scientists have discovered many signs that rivers, lakes and entire oceans of fresh water existed on the surface of Mars in ancient times.

Measurements by the Curiosity rover show that these reservoirs were filled with fresh water, theoretically suitable for the origin of life.

Such discoveries lead planetary scientists to argue about whether there were sufficient organic reserves on Mars for this, and also whether life existed on the fourth planet in the past.

Even more controversial is the nature of periodic emissions of methane from the surface of Mars, which were recorded by the Mars Express probe and the Curiosity rover a few years ago.

“Eternal” Martian bacteria

Professor Hoffman and his colleagues were interested in how long potential spores of Martian microbes could survive inside the Martian soil at a relatively large, but at the same time accessible to bacteria depth.

To do this, scientists prepared cultures of terrestrial bacteria of the species Deinococcus radiodurans, which are especially resistant to radiation, as well as five other types of microbes.

The researchers immersed the spores of these single-celled organisms in soil samples similar to Martian soils in chemical and mineral composition, as well as in structure and other mechanical properties.

After that, the biologists placed the samples in a special chamber, where Martian temperatures, humidity levels and background radiation were simulated.

The role of the latter was played by beams of gamma rays and high-energy protons, with which the researchers irradiated the soil.

Subsequent observations of changes in the state of bacterial spores showed that Deinococcus radiodurans, as well as several other microbes, were able to survive in the Martian soil for several geological epochs.

In particular, scientists have found that “sleeping” cells of the first type of bacteria will be able to awaken and multiply even after 280 million years, if they are immersed to a depth of ten meters from the surface of Mars.

These same microbes will be able to live for several million years even if they are placed at a depth of only 10 centimeters from the surface, and when immersed to a depth of two meters, they will remain viable for several tens of millions of years.

This will potentially allow the detection of spores of Martian microbes using the drilling rigs of the rover from the suspended Russian-European ExoMars mission, the authors of the study concluded.

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