Mars rovers cannot detect signs of life on Mars

Robots currently exploring Mars may not be able to detect potential traces of life on the Red Planet, according to new research.

The twin Viking orbiters that NASA sent to Mars nearly half a century ago discovered that the Red Planet had liquid water early in its formation, about three to four billion years ago. Subsequent missions confirmed these findings, suggesting that organisms may have once lived there, and may still do so; Because on earth, life is present almost wherever there is water.

However, the two Viking landers did not detect any obvious indigenous organic chemicals in the Martian soil; Even on a part-per-million scale. Even the latest and most advanced instruments of the Curiosity and Endurance rover have found only traces of simple organic molecules in the ancient beds of Martian lakes and river deltas. These compounds are not hard evidence for life: scientists emphasize that they could have been produced by geological processes.

It is not clear whether the hunt for past or current life on Mars has been fruitful or not; Because either the Red Planet has always been barren or the probes we’ve sent aren’t sensitive enough to detect any life there. To help solve this mystery, scientists have tested instruments that are currently on Mars or likely to be sent to Mars along with highly sensitive laboratory equipment.

The predecessor of Mars rover endurance
NASA’s Endurance rover posted this selfie of itself and one of 10 samples it took from a region called Three Forks on Mars. This image was taken by the WATSON camera on the rover’s robotic arm on January 20, 2023, the 648th day on Mars.

Researchers have analyzed samples from the Red Stone, the remains of a river delta in the Atacama Desert in Chile. These sediments, which were formed in very dry conditions about 100 to 160 million years ago, are very similar to the island crater on Mars that is currently being explored.

Redstone is regularly affected by mists that provide water for the resident microbes. Using modern laboratory techniques, scientists have found a combination of biochemical substances belonging to extinct and living microorganisms. About half of the DNA sequences identified in Redstone come from the “dark microbiome”; That is, microbes that researchers have not yet successfully described.

However, experimental versions of instruments already on Mars or about to be sent — including one that is 10 times more sensitive than Curiosity — have struggled to detect organic signatures within the Redstone samples.

“I expected that the test bed tools used to identify the evidence of life in Redstone that we knew existed, and the laboratory equipment would be used,” said lead study author Armando Azua-Bustos of the Center for Astrobiology in Madrid. use, to perform better; But they didn’t have it.”

The findings suggest that it would be difficult (or impossible) for Mars probes to detect the kinds of low-level organic matter that we would now expect to find on the Red Planet if life existed on Mars three billion years ago.

“We’re still learning how to detect evidence of life on Mars,” says Azoa Bustos. The current nature of the instruments sent has its limitations. But this is not because of their bad design; We are still learning.”

Redstone of the Atacama Desert
Scientists believe the remains of ancient life in the redstone of the Atacama Desert are similar to what can be found on Mars, but current rovers’ instruments cannot detect these signs.

The researchers suggest that future missions to Mars should seek to return samples from the Red Planet to Earth for scientists to test with the most advanced equipment available to help solve the mystery of Martian life. NASA and the European Space Agency plan to return the material collected by Endurance to Earth by at least 2033.

Future research could analyze the dark microbiome of Redstone. According to Azoea Bustos, these microbes are either so different from known microorganisms as to challenge current classifications, or they are remnants of life that was present in the area millions of years ago (when there was still water) but now has no living relatives. We can compare them.

Overall, Azoea Bustos points out that many possible remains will be identified at Redstone. He says the new work is “like sampling a street in New York to determine the characteristics of New York as a whole.”

The researchers published their findings last month in the journal Nature Communications.

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