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Mission simulated in the Chilean desert shows how a rover could detect life on Mars

A trial mission at NASA in the Atacama Desert as Mars.
Image: Stephen Pointing

Using the arid Atacama Desert in Chile as stand-in for Mars, the researchers have shown that it is possible to use a freestanding simulator mounted on a rover to detect life beneath a desolate surface. Fortunately, the test resulted in the discovery of a resistant microorganism, exactly the type of creature that could hide deeply below the Martian surface.

The new research published today on Frontiers in Microbiology describes an experimental NASA rover mission in the Atacama desert of Chile that could reflect a future mission to Mars. The experimental rover and drill, designed by the Robotics Institute of Carnegie Mellon and funded by NASA, has successfully recovered microorganisms under the surface, specifically, a resistant bacterium to great resistance. The test provided the justification of a life hunting mission to Mars, but the experiment was not without its challenges and limitations. As the new research demonstrated, finding life on Mars (if it still exists) will require some serious technological innovations, lots of money and a bit of luck.

Millions of years ago, Mars had a temperate climate and liquid water on its surface, providing a potential life environment. Today, life is unlikely to exist on the surface. The lethal levels of radiation bathe the Red Planet, and its tortured surface contains few traces of liquid water. During the Martian summer, daytime temperatures close to the equator can reach a temperature of 68 degrees Celsius (20 degrees Celsius), but at night it falls to a reckless cold -148 degrees F (-100 degrees Celsius).

The rover robot simulator in use in the Atacama desert.
Image: Stephen Pointing

The conditions under the surface are a different story, according to Stephen Pointing, a researcher at the Yale-NUS School in Singapore and the main author of the new study. Just below the surface, rocks and sediments provide shelter from the previous extreme conditions, providing a potential habitat for life.

As Pointing explained to Gizmodo, there is no place on Earth as the surface of Mars, but the ground below the Atacama Desert in Chile offers a decent analog.

"Some of the more Earth-like soils on Earth are in the Atacama desert," Pointing said. "There is little water intake for the desert and the soils have become poor and very salt nutrients over time and, chemically, they look like soles of Mars in various ways. In preparation for future missions on Mars we use places such as the Atacama Desert to test the theories about the distribution of life and the new technologies to seek life. "

For the experiment, Pointing and his colleagues unfolded a four-wheeled autonomous vehicle equipped with a robot simulator that successfully recovered the samples from underground sediments from a depth of 80 centimeters. The researchers compared the samples collected by the seller to samples collected by hand. Then, using DNA sequencing, Pointing and colleagues demonstrated that bacterial life in the sediments recovered by both methods were similar, which shows that the rover technique was a success.

That being said, the bacteria were not uniformly distributed by the desert, and instead they were located in seemingly random patches. This was due to "limited availability of water, low nutrients and geochemistry of the soil," Pointing said, adding that, in search of life on Mars, "we may be facing larger" find-a-needle "The problem of" Haystack " .

However, the new study is the first to demonstrate that microorganisms are distributed within specific inhabitable areas of the subsoil below the surface of the Atacama desert.

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"The surface admits an omnipresent and unimportant community dominated by photosynthetic Chlorophyll and these have been widely informed before, "Gizmodo said." Just underneath the surface is where it starts to be interesting. We have seen that with the increasing depth the bacterial community has been dominated by the bacteria that can thrive in extremely salty and alkaline soils. In turn, they were replaced at depths of up to 80 cm by a unique group of bacteria that survive by metabolizing methane as a food source. "

Exciting, the new research shows that the underground surface of Atacama can withstand highly specialized microbes that could survive saltwater Martian soil. On the other hand, Mars is known to contain abundant amounts of methane on the surface, pointing to the possible presence of methane microorganisms under the Martian surface, according to the new article. An important next step for Pointing and his team will be to discover how subsurface microbes in Atacama can survive. To do this, they are looking for the possible strategies that bacteria use to survive long periods without water and exposure to extremely salty conditions. In addition, the team wants to return to the Atacama Desert with a rover capable of drilling 2 meters (6 feet) away.

With all this, it's time to make some checks of reality.

The researchers successfully used a probe to detect life on Earth, which is certainly not terribly difficult even when the environment becomes a desert. Life has flourished on earth for thousands of millions of years, and is ubiquitous, even appearing on the rock thousands of feet below the surface. Yes, the new investigation was carried out in a place similar to Mars, but it is still not Mars. In the best case, the new study presents the scientific justification for a future life-hunting mission to the red planet, but all the speculation about life on Mars remains that.

Another important limitation of the new research is that sediment samples were tested in a laboratory and not by equipment in the vehicle itself. Pointing to himself admitted that this will present a great obstacle for Mars mission planners.

"For an explorer on Mars there is a challenge to identify the unequivocal signs of life," he said. "The DNA sequencing method we use is excellent here on Earth, but it is currently too complex to be reliably deployed on Mars. That's why indirect detection of other known molecules that are formed by living cells is probably the focus that the missions with Mars will be long-term. "

In other words, it would make more sense for a future rover to look for biosignatures, the remains of biological life, such as inexplicable traces of molecular oxygen combined with methane, accumulated batteries of microbes (stromatolites) and remains of fossil, fat and steroids. If something was detected, then we would need new experimental techniques to prove if some Martian bacteria were really alive and capable of active metabolism, "Pointing said.

Finally, and perhaps more discouragingly, there is the cost of sending such a mission to Mars. NASA and ESA plan to send rovers to Mars over the next few years, but it is not clear if no agency has the technological capability or funds to organize a mission capable of returning ground and Martian land samples to the analysis. As SpaceNews reported only this week, NASA is unlikely to return Mars samples in 2020, mainly due to the expense.

Pointing out admitted that a return mission would be expensive, costing hundreds of millions of dollars.

"However, the research will help us address 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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