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Simulated mission in the Chilean desert shows how a rover could detect life on Mars



A NASA rover mission in the Martian-style Atacama Desert.
Image: Stephen Pointing

Using the barren Atacama Desert in Chile as a replacement for Mars, researchers have shown that this is possible with an autonomous rover drill that captures life beneath a desolate surface. Encouragingly, the test led to the discovery of a resilient microorganism – the kind of creature that could lurk deep beneath the surface of Mars.

The research published today in Frontiers in Microbiology describes a NASA rover mission in the Atacama Desert in Chile reflecting a future mission to Mars. The experimental drill and drill, designed by the Robotics Institute of Carnegie Mellon and funded by NASA, has successfully recovered sub-surface microorganisms – particularly a robust, salt-resistant bacterial species. The test provided the rationale for a life-hunting mission to Mars, but the experiment was not without its challenges and limitations. As the new study has shown, life on Mars, if there is one, requires some serious technical innovation, a lot of money and a bit of luck.

Billions of years ago, Mars had a temperate climate and surface liquid water that provided a potential environment for the emergence of life. Today, life is unlikely to exist on the surface. Deadly radiation levels bathe the Red Planet and its tortured surface hardly contains traces of liquid water. During the Martian summer, daytime temperatures near the equator can reach a mild 20 degrees Celsius, but at night temperatures drop to -148 degrees Fahrenheit (-100 degrees Celsius).

The rover's robot in action in the Atacama Desert.
Image: Stephen Pointing

The sub-surface conditions, according to Stephen Pointing, researcher at Yale-NUS College in Singapore, and the head of another story author of the new study. Just below the surface, rocks and sediment provide protection from the extreme conditions and provide a potential habitat.

As Pointing Gizmodo explained, there is no place on earth that resembles the Martian surface, but the soil beneath the Atacama Desert in Chile provides a decent analogue.

"Some of the most Mars-like soils in the world are in the Atacama Desert," Pointing said. "There is very little water in the desert, and the soil is very nutrient-poor and extremely salty over time. They are similar in many respects to the soils on Mars. To prepare for future missions to Mars, we use places like the Atacama Desert to test theories of how life is distributed and new technologies for finding life. "

For the experiment, Pointing and his colleagues used an autonomous four-wheeled rover equipped with a robotic drill that successfully extracted sediment samples from a depth of 80 centimeters (31 inches). The researchers compared the samples collected from the rover with the samples collected by hand. Using DNA sequencing, Pointing and his colleagues showed that the bacterial life in the sediments obtained by both methods was similar, indicating that the rover technique was a success.

That is, the bacteria were not evenly distributed in the desert. and instead found themselves in seemingly random patches. This is due to "limited water availability, scarce soil nutrients, and soil geochemistry," Pointing said, adding that in finding life on Mars, "we may find the largest bottleneck ever found -a-haystack." "

Nevertheless, the new study shows for the first time that microorganisms in certain subterranean habitable zones are distributed beneath the surface of the Atacama Desert.

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" The surface supports an omnipresent and unobtrusive community dominated by photosynthesis Chloroflexi and this has been widely reported, "Pointing told Gizmodo. "Just below the surface it starts to get interesting. We have seen that with increasing depth, the bacterial community has been dominated by bacteria that can thrive in the extremely salty and alkaline soils. They have been replaced to a depth of 80 cm by a unique group of bacteria that survive by metabolizing methane as a food source. "

The new research shows excitingly that Atacama's subsurface can support highly specialized microbes that could potentially help them survive the salty Martian soil. In addition, it is known that Mars contains abundant methane at the surface, suggesting the possible presence of methane-consuming microorganisms beneath the Martian surface, the new paper states. An important next step for Pointing and his team will be to find out how the Atacama underground microbes can survive. To this end, they are studying possible strategies that will allow bacteria to survive for long periods without water and extremely salty conditions. In addition, the team wants to return to the Atacama Desert with a rover capable of drilling 2 meters deep.

After all, it's time for some reality checks.

The researchers successfully used a probe to detect life on Earth, which is not incredibly difficult, even if the environment is a desert. Life has thrived on Earth for billions of years, and it is omnipresent and even appears in rocks thousands of feet below the surface. Yes, the new research was done in a Mars-like location, but it's still not Mars. At best, the new study provides a scientific rationale for a future life-hunting mission for the Red Planet, but any speculation about life on Mars remains exactly that.

Another important limitation of the new research is sediment The samples were tested in a laboratory and not with any devices on the rover itself. The suggestion that this is a major obstacle for Mars mission planners.

"For a rover on Mars, the challenge is to see clear signs of life," Pointing said. "The DNA sequencing method we use is terrific here on Earth, but currently too complex to work reliably on Mars. Therefore, the indirect detection of other molecules known to be formed by living cells is likely to be the approach that Mars missions will follow in the near future. "

In other words, this would be a future rover of meaningful biosignature searches – the remnants of biological life, such as unexplained traces of molecular oxygen in combination with methane, accumulated microbial strata (stromatolites), and traces of fossilized wastes, fats, and steroids. If such a thing could be discovered, "then we need new experimental techniques to test whether Marsbacteria are actually alive and capable of active metabolism," Pointing said.

Finally, there are the costs that may be daunting to send such a mission to Mars. NASA and ESA plan to ship rovers to Mars over the next few years. However, it is not clear whether one of the agencies has the technological capacity or the resources needed to organize a mission that can return Mars rock and soil samples for analysis. As SpaceNews reported earlier this week, it is unlikely that NASA will return Mars samples in the 2020s, mainly due to cost.

Pointing admitted that a repatriation mission would be expensive and cost hundreds of millions of dollars.

"However, research will help us answer one of the biggest questions we can ask," he said. "Is Earth the only planet that supports life?"

[Frontiers in Microbiology]


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