NASA says Perseverance sample provides clearest sign yet of ancient microbial life on Mars

NASA announced Wednesday that a sample collected by the Perseverance rover contains what agency leaders have called the clearest sign yet of past microbial life on Mars.

The agency's new administrator, Sean Duffy, said the sample recovered from mud-like rocks in Neretva Vallis — a branch of Jezero Crater where a river once flowed — has been declared the "clearest sign of life" found on the Red Planet. At a news conference, NASA Associate Administrator Nick Fox said, "This is the kind of signature that we would see that was made by something biological." Scientists described small, seed-like and spot-like features in the rock, nicknamed "poppy seeds" and "leopard spots," and reported the presence of iron and phosphorus in those features.

Researchers said the microscopic structures and associated chemical signatures were observed in ancient, mud-rich rock layers that formed in the crater billions of years ago when liquid water was present. Principal investigator Joel Hurowitz and other team members said the patterns and mineral assemblages match alteration products produced on Earth when microbes break down organic material and concentrate certain elements, notably iron and phosphorus.

Perseverance has been exploring Jezero Crater since landing in 2021 and has been systematically characterizing the crater's sedimentary deposits. NASA officials noted that the rover previously identified other potentially biological signatures, including a vein-filled, arrowhead-shaped rock described in 2024 that showed chemical and structural features consistent with microbial processes. The new sample was collected from a site known as Neretva Vallis within the crater's lake- and river-deposited sediments.

Scientists cautioned that interpreting ancient rocks on another planet requires careful analysis. While the agency presented the findings as the clearest sign to date of past life on Mars, researchers emphasized that the observed features are being evaluated against alternate, nonbiological processes that can yield similar mineral patterns. Laboratory and comparative studies of terrestrial analogues and additional measurements from rover instruments have been used to test those alternatives, the team said.

The detection relied on Perseverance's suite of geochemical and imaging tools, which can map elemental abundances and textures at small scales. Team members reported elevated iron and phosphorus concentrations localized within the seed- and spot-like structures, characteristics that on Earth are sometimes produced by microbial decomposition of organic matter and subsequent mineral precipitation. The rover's sampling system collected material from the units for detailed in-situ study and archiving.

NASA officials said the results were presented publicly so the broader scientific community could review the data and approaches. Agency scientists indicated they plan to publish full analyses and methods in peer-reviewed journals and make relevant data available to independent researchers. Additional examination of the samples, comparisons with terrestrial biosignatures and further rover observations were described as part of an ongoing effort to test the biological interpretation.

If confirmed through broader scientific review and additional lines of evidence, the finding would have profound implications for understanding the distribution of life in the solar system and the conditions on early Mars. For now, NASA framed the announcement as a major step in a continuing investigation: a set of features and chemical signatures that most closely match biological alteration among the Mars data collected so far.

The agency said more detailed results and follow-up studies would be released in the coming weeks and months as the team completes additional analyses and prepares manuscripts for the scientific literature. The Perseverance mission and its scientific partners will continue to examine the crater's sedimentary record and to place the newly reported signatures in the broader context of Mars' environmental history.