NASA rover finds potential sign of ancient life in Martian rocks

A sample collected by NASA's Perseverance rover from rock formed billions of years ago in a lake on Mars contains potential signs of ancient microbial life, according to scientists. However, the minerals found in the sample could also form through non-biological processes.

This discovery, detailed in research published on Wednesday, is one of the strongest pieces of evidence yet suggesting that Mars may have once supported life.

Since landing on Mars in 2021, the rover has been exploring Jezero Crater, located in the planet's northern hemisphere, which was once flooded with water and contained an ancient lake basin. Perseverance has been collecting rock samples and regolith, which it then analyses using its onboard instruments.

The newly analysed sample, known as the Sapphire Canyon sample, was obtained from the Bright Angel rock formation, which is composed of fine-grained mudstones and coarse-grained conglomerates. These are sedimentary rocks made up of gravel-sized particles cemented by finer sediments.

Joel Hurowitz, a planetary scientist from Stony Brook University and the lead researcher of the study published in Nature, said that a "potential biosignature" was identified in the ancient sedimentary rocks. This took the form of two minerals that seemed to have formed through chemical reactions between the mud of the Bright Angel formation and organic matter in the mud: vivianite, an iron phosphate mineral, and greigite, an iron sulfide mineral.

Hurowitz explained that these reactions likely occurred soon after the mud was deposited on the lakebed. On Earth, similar reactions—where organic matter and chemicals in mud form minerals like vivianite and greigite—are often driven by microbial activity. These microbes consume the organic matter and produce these minerals as a byproduct of their metabolism.

However, Hurowitz was cautious, stating that while this could be a potential biosignature, it is not definitive. He pointed out that chemical processes unrelated to biology can also produce similar reactions, and these cannot be ruled out based on the rover's data alone.

Mars was not always the barren planet it is today; it once had liquid water on its surface. Scientists believe microbial life could have existed in Jezero Crater, as river channels likely spilled over the crater's walls and formed a lake over 3.5 billion years ago.

The Sapphire Canyon sample was collected in July 2024 from rocky outcrops at the edges of Neretva Vallis, an ancient river valley that formed as water flowed into Jezero Crater.

This sample provides a new example of a potential biosignature that researchers can study to determine whether these features were created by life or if natural processes mimicked biological activity. Hurowitz added that future research would generate testable hypotheses to assess whether biology was responsible for these features in the Bright Angel formation. If the sample is returned to Earth, further analysis could help confirm or rule out biological involvement.

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