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Research raises questions: Are instruments taken to Mars sensitive enough to find life?

Study in Chile desert finds NASA Mars mission instruments unlikely to detect signs of life in Earth's most arid regions

A study in Chile's Atacama Desert has found that instruments taken to Mars on NASA's Curiosity and Perseverance missions might not be sensitive enough to find signs of life.

A study led by Armando Azua-Bustos, a researcher based at Spain's Center of Astrobiology, looked at samples collected from Red Stone, a dried-up river delta more than 100 million years old in the Earth's oldest and driest desert.

The area was chosen because it has a similar geology to the delta area currently being studied by NASA's Perseverance on Mars. In the samples, the researchers found active microbial life detected by DNA extraction and gene sequencing, microscopy, and growth of a few microbial strains in the lab. Most of the bugs found were dubbed "microbial dark matter" owing to their genetic information stemming from as yet unknown microorganisms. They also found chemical signatures from extinct biological life.

However, using sensors equivalent to those taken to Mars, as well as those scientists plan to take on future missions, the research came up with little evidence of life.

"Our analyses by testbed instruments that are on or will be sent to Mars unveil that although the mineralogy of Red Stone matches that detected by ground-based instruments on the red planet, similarly low levels of organics will be hard, if not impossible to detect in Martian rocks depending on the instrument and technique used," the paper, published in Nature Communication today, said.

Perseverance rover has already dropped off a cache of rock sample that NASA astrobiologists might one day return to Earth — providing they can figure out how to send a spacecraft from Earth to Mars to collect the crucial evidence and return them to Earth for analysis by 2033.

The researchers studying Chilean rocks underscore the need for this mission. "Our results stress the importance in returning samples to Earth for conclusively addressing whether life ever existed on Mars," the study said.

In an accompanying article, Nasa research scientist Carol Stoker said the Red Stone work showed how critical it is to test instruments designed for life detection on other planets by using samples from relevant Earth analogs prior to selecting them for flight missions. "If the biosignatures can't be detected in Earth samples, where both current and ancient life is clearly documented, we should not expect these instruments to be capable of detecting evidence of life from Mars' early history," she said.

The space agency has been asked to provide further context.

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