Perseverance's Sample Could Be Its Most Important Yet

NASA's Mars rover Perseverance has uncovered rocks in a dry river channel that may hold potential signs of ancient microscopic life, scientists reported Wednesday. They stressed that in-depth analysis is needed of the sample gathered there by Perseverance—ideally in labs on Earth—before reaching any conclusions. Roaming Mars since 2021, the rover cannot directly detect life. Instead, it carries a drill to penetrate rocks and tubes to hold the samples gathered from places judged most suitable for hosting life billions of years ago. The samples are awaiting retrieval to Earth—an ambitious plan that's on hold as NASA seeks cheaper, quicker options, reports the AP.

Calling it an "exciting discovery," a pair of scientists who were not involved in the study—SETI Institute's Janice Bishop and the University of Massachusetts Amherst's Mario Parente—were quick to point out that non-biological processes could be responsible. "That's part of the reason why we can't go so far as to say, 'A-ha, this is proof positive of life,'" lead researcher Joel Hurowitz of Stony Brook University told the AP. "All we can say is one of the possible explanations is microbial life, but there could be other ways to make this set of features that we see."

Either way, Hurowitz said it's the best, most compelling candidate yet in the rover's search for potential signs of long-ago life. It was the 25th sample gathered; the tally is now up to 30, with six more to go. Collected last summer, the sample is from reddish, clay-rich mudstones in Neretva Vallis, a river channel that once carried water into Jezero Crater. This outcrop of sedimentary rock, known as the Bright Angel formation, was surveyed by Perseverance's science instruments before the drill came out.

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Along with organic carbon, a building block of life, Hurowitz and his team found minuscule specks, dubbed poppy seeds and leopard spots, that were enriched with iron phosphate and iron sulfide. On Earth, these chemical compounds are the byproducts when microorganisms chomp down on organic matter. The findings appeared in the journal Nature. When Perseverance launched in 2020, NASA expected the samples back on Earth by the early 2030s. But that date slipped into the 2040s as costs swelled to $11 billion, stalling the retrieval effort.