By Sarah Cope | 2025-10-24

As NASA’s Perseverance rover toiled away at its mission to collect samples from an ancient dry riverbed on Mars in July 2024, it encountered a partially buried rock that scientists have dubbed 'Cheyava Falls.'

The rover drilled a sample, 'Sapphire Canyon,' from the Cheyava Falls rock, which is within the 'Bright Angel' formation -- a series of rocky outcrops on the edge of the dry river valley in the Red Planet's Jezero Crater.

With its SHERLOC instrument (Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals), the rover scanned the sample and identified the presence of organic compounds.

Analysis showed mineralogical and chemical patterns consistent with a potential biosignature, which might show the presence of biological processes, but does not definitively offer proof of life, per a September paper in the Nature journal.

"We put it out to our scientific friends to pressure test it, to analyze it, and go, did we get this right? Do we think this is signs of ancient life on Mars?" NASA's acting administrator Sean Duffy said at a September 11 news conference.

"They said, 'Listen, we can't find another explanation.' So this very well could be the clearest sign of life that we've ever found on Mars."

Sapphire Canyon sample

A study of the Sapphire Canyon sample indicates water once flowed over it. The dark and light spots on its surface are similar to a pattern observed on Earth that is indicative of the living processes of microbes.

Perseverance’s PIXL instrument (Planetary Instrument for X-ray Lithochemistry) identified that black rings around the spots contained iron and phosphate.

Scientists say the spots show a pattern of minerals arranged into "reaction fronts" that could indicate a chemical and physical reaction.

"On the one hand, we have our first compelling detection of organic material, distinctive colorful spots indicative of chemical reactions that microbial life could use as an energy source, and clear evidence that water -- necessary for life -- once passed through the rock," Perseverance project scientist Ken Farley said.

"On the other hand, we have been unable to determine exactly how the rock formed and to what extent nearby rocks may have heated Cheyava Falls and contributed to these features," he said, following the initial discovery in 2024.

Study of the sample found that the Bright Angel formation’s sedimentary rock is comprised of clay and silt.

Clay and silt soil are rich in organic carbon, sulfur, rust and phosphorus, and "could have been a rich source of energy for microbial metabolisms," said Perseverance scientist Joel Hurowitz of Stony Brook University, New York.

"But just because we saw all these compelling chemical signatures in the data didn’t mean we had a potential biosignature," said Hurowitz, who is the lead author of the Nature paper.

"We needed to analyze what that data could mean."

Building on a legacy

The Nature paper describes how the Perseverance rover's instruments were able to identify the presence of organic compounds, drill, and analyze the sample.

This provided scientists with enough information for study and analysis.

The finding builds on a legacy of missions and discoveries that have honed scientists’ ability to analyze samples from millions of miles away, detect habitability, and identify biosignatures.

Perseverance is the fifth of NASA’s Mars rovers, following Curiosity, Opportunity, Spirit and the original Mars rover, Sojourner.

The Curiosity rover, launched in 2012, discovered that its landing site, the Gale Crater, once had conditions suitable for microbial life and laid the foundation for Perseverance’s mission and discoveries.