The sample, known as Sapphire Canyon, was drilled from a rock nicknamed Cheyava Falls in July 2024 while the rover explored the ancient riverbed of Jezero Crater. After a year of close analysis, researchers said it remains the mission’s best candidate for a potential biosignature – a chemical or structural feature that may have a biological origin.
The findings were published this week in the journal Nature.
“This is the closest we’ve come to identifying signs of life on Mars,” acting NASA administrator Sean Duffy said. “The discovery of a potential biosignature is a breakthrough that takes us a step further in understanding the Red Planet, and towards the day when humans will set foot there.”
Perseverance encountered Cheyava Falls within the so-called Bright Angel formation, a cluster of rocky outcrops at the mouth of Neretva Vallis – a river channel that once funnelled water into Jezero Crater.
Initial scans showed the rocks were rich in clay and silt, which on Earth are prime environments for preserving traces of microbial activity. They also contained organic carbon, sulphur, phosphorous and oxidised iron – all chemical ingredients that microbes on Earth can use for energy.
Closer examination revealed a distinct leopard-spot pattern on the surface of the rock, made up of two iron-rich minerals: vivianite and greigite. On Earth, both are commonly associated with decaying organic matter or produced by microbial processes.
“The combination of these compounds could have been an energy source for microbial metabolisms,” lead author Joel Hurowitz, from Stony Brook University in New York, said. “But while the signatures are compelling, we needed to test what else they could mean.”
Although these minerals can also form without life, the conditions needed – such as extreme heat or highly acidic environments – do not appear to be present in the Bright Angel rocks.
Perhaps most surprising is the age of the samples. The Bright Angel formation contains some of the youngest sedimentary rocks Perseverance has examined so far. Scientists had long assumed that if life existed on Mars, traces would be found in much older rocks.
This suggests Mars may have remained habitable for longer, or later in its history, than previously thought.
“Astrobiological claims demand extraordinary evidence,” said Katie Stack Morgan, Perseverance’s deputy project scientist at NASA’s Jet Propulsion Laboratory. “Publishing this work in a peer-reviewed journal is a vital step. It gives the global scientific community the opportunity to scrutinise, confirm or challenge what we’ve found.”
The results mark a milestone for the Perseverance mission, which has now collected 27 rock cores since landing in 2021. NASA hopes to one day return these samples to Earth for laboratory analysis – a mission expected to provide the most definitive test of whether life ever existed on Mars.
The rover also carries instruments to monitor the Martian climate and test materials for future human explorers.
“This discovery shows the value of long-term, carefully planned missions like Perseverance,” said Nicky Fox, head of NASA’s Science Mission Directorate. “By making the data public, we’re giving the entire scientific community the chance to deepen our understanding of Mars and the possibilities of life beyond Earth.”
The Perseverance rover is managed by NASA’s Jet Propulsion Laboratory, operated by Caltech, as part of the agency’s Mars Exploration Program.