NASA unveiled results from the Perseverance rover, announcing that a rock core collected in July 2024 from an ancient riverbed in Mars’ Jezero Crater contained potential biosignatures - substances or structures that may have a biological origin - while an international team published the analyses in Nature. The findings centered on a sample nicknamed Sapphire Canyon, drilled from a rock called Cheyava Falls in the Bright Angel formation, and pointed to mineral patterns and organic signals that researchers said could be the closest evidence yet of ancient microbial life on Mars.
Cheyava Falls, named after a Grand Canyon waterfall, drew the science team’s attention for unusual textural patterns. At the Bright Angel outcrop - at the base of the northern side of the Neretva Vallis river channel - Perseverance detected fine-grained mudstones rich in oxidized iron, phosphorus, sulfur, and organic carbon. The rover’s laboratory suite, including PIXL (Planetary Instrument for X-ray Lithochemistry) and SHERLOC (Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals), mapped the rock’s surface chemistry and documented nodules, grains, and reaction fronts enriched with iron phosphate and iron sulfide associated with organic carbon. SHERLOC also detected a Raman spectral feature known as the G-band - a smoking gun indicator for organic material - with especially strong signals at a site dubbed Temple of Apollo, where vivianite and greigite were abundant.
On the rock surface, the team observed tiny black specks nicknamed poppy seeds and a set of larger, irregular dark spots with lighter halos called leopard spots. Within these spots, PIXL measured high concentrations of iron and phosphates. The team also identified white calcium sulfate veins cutting across Cheyava Falls - evidence that water once flowed through fractures - while hematite occurred between the veins. Researchers proposed that reactions involving hematite could have released iron and phosphates and produced the spotted patterns, a process that can create conditions conducive to life. The mineral suite included vivianite and greigite, both linked on Earth to microbial processes in aquatic settings; some microbes can produce greigite, and vivianite commonly appears in sediments, peat bogs, and near decomposing organic matter.
Jezero Crater was once a lake fed by rivers, and mission scientists considered its ancient delta a prime location to search for signs of past microbial life. Layered beds in the Bright Angel formation suggested a dynamic environment of flowing rivers and standing water, and over time the lake shrank into a large delta built by sediments carried by ancient currents. Mars is a cold, dry desert today, but billions of years ago it had a thicker atmosphere and water.
“These findings met NASA’s criteria for potential biosignatures,” the agency said. “This is a potential biosignature. That means it could have a biological origin, but more study is required,” said Lindsay Hays, senior scientist for Mars Exploration at NASA, according to a report by ABC News. The team outlined two scenarios: the features could have formed abiotically through geochemical reactions, or they could reflect microbial activity, as occurs on Earth. Researchers noted geologic pathways that could produce similar reactions, but structures associated with sulfur generally form only at high temperatures, and the Bright Angel rocks did not appear heated.
“As soon as we saw the rocks, we realized that an interesting chemical process was happening here, so we were very excited,” said Joel Hurowitz of Stony Brook University, the study’s lead author, according to a report by BBC News. He said chemical reactions occurred in mud settling at the bottom of a lake, formed by the combination of the mud and organic materials, which reacted to create new minerals. “We haven’t found life, but we’ve found features in the rocks that could be explained by biology, microbial processes on Earth,” said Sanjeev Gupta, an author of the study.
Perseverance landed in Jezero Crater on February 18, 2021, and explored the lakebed and remnants of the ancient river system in search of microfossils. The rover collected more than 30 samples of Martian rock and soil, including 28 from Jezero for the Mars Sample Return campaign, and had room for six more. NASA officials described Sapphire Canyon, the mission’s 25th geological sample, as one of the most promising and said the initial analysis did not rule out a biological origin for its features. The agency reiterated that the rover was not equipped to detect life and that confirmation would require returning the sample to Earth.
How to execute the return remained in question. NASA said the plan faced delays and budget pressure, with costs pushing the project into the 2040s, and placed its future under review as part of a multi-mission campaign with the European Space Agency. The agency said it was analyzing options - technology, budget, and timeline - to decide how to return the samples as efficiently as possible. Scientists said Sapphire Canyon’s sealed core, now stored in a titanium tube on Mars, was among the highest-priority samples to be returned.
NASA said the finding was surprising because it concerned some of the youngest sedimentary rocks studied by Perseverance, formed billions of years ago from sediment in a dusty riverbed. The combination of unusual organic minerals and organic carbon in an ancient fluvial context made the discovery a step toward assessing the biological potential of Mars and raised the possibility that the planet may have been habitable over a more extensive or more recent period than previously assumed.
“To be certain, we must eventually return these samples to Earth,” said Hurowitz. Scientists said the study provided testable hypotheses to determine whether biology was responsible for the textures and mineral assemblages in Bright Angel - work they could assess if Sapphire Canyon was brought home.
The preparation of this article relied on a news-analysis system.