NASA: Perseverance found possible biosignatures in Martian rock

NASA’s Perseverance rover has identified a potential sign of past life on Mars — not a definitive detection, but perhaps the most compelling hint yet.

On Sept. 10, 2025, NASA announced that a rock found on Mars last year, called “Cheyava Falls,” continues to show signs consistent with past microbial life.

The rock is covered in patterns of “leopard spots” that may have formed through chemical reactions known to fuel life. On Earth, spots like these are often associated with the fossilized record of microbes. Though other explanations still remain, Perseverance scientists have now published a peer-reviewed paper that finds no particularly strong evidence for any of the alternatives studied.

That doesn’t mean Cheyava Falls is a definite sign of life. But it was enough to make Secretary of Transportation Sean Duffy, who is currently serving as Acting Administrator of NASA, call the discovery “the closest we have ever come to discovering [ancient] life on Mars.”

The finding marks a big step forward in a lengthy process, one that could possibly end in the discovery that life has existed beyond Earth — and that it is common enough to have inhabited our neighboring planet.

What Perseverance saw

On July 21, 2024, NASA’s Perseverance rover spotted a strange rock partially buried in a dry riverbed. White streaks hinted water once flowed through the stone, and Perseverance also found signs of organic molecules, the building blocks of life. But what really stood out was a smattering of dark and bright spots along the rock’s surface. On Earth, such “leopard spots” are mainly known to form in two ways: from microbes, or through chemical reactions that can provide fuel for life.

Scientists were intrigued. Even if Cheyava Falls wasn’t marked by life, it was still the first single place on Mars to show signs of once hosting all three of life’s main ingredients: liquid water, organic molecules, and an energy source. Billions of years ago, this rock could have met all the conditions life needs to thrive.

Now, members of the Perseverance science team have had time to collect more data, think up alternative explanations, and have their ideas checked by other researchers. Though they proposed several other ways to produce Cheyava Falls’ leopard spots without microbial life, none quite match the bigger picture. The spots can be produced when organic molecules are cooked under high temperatures or exposed to acidic conditions, for example, but neither possibility seems to fit the rock’s history.

Alien life or alien hype?

That still does not mean we have found life on Mars. Investigating any potential signs of past life in Cheyava Falls will be a long, complicated journey. 

“This paper takes the next step,” says Bruce Betts, chief scientist at The Planetary Society, “but further study by other scientists will be required before we can see if this rock provides an answer to the profound question of whether there was once life on another world.”

Even if scientists had no way to explain Cheyava Falls except through past microbial life, there would be reason to remain both cautious and excited. As researchers focus more on the rock’s potential signs of life, they may come up with new explanations unrelated to life that no one had thought of before. 

This is what happened in 1996, when NASA scientists announced that the meteorite ALH84001 appeared to show fossils of ancient bacteria-like life on Mars. The public was excited, but continued study ultimately found that the best explanation for the “fossils” had nothing to do with  life.

Yet there is only so much more scientists can do to get to the bottom of Cheyava Falls with Perseverance alone. Though the rover can run experiments and make major discoveries on its own, it is limited by the tools it can carry. 

“We basically threw the entire rover science payload at this rock,” said Katie Stack Morgan, Perseverance project scientist. “We're pretty close to the limits of what the rover can do.”

This is by design, Morgan explained, because Perseverance was launched as part of the first step in a larger mission: one to bring back the first samples from another planet. 

Bringing back Cheyava Falls

Since 2020, Perseverance has been laying the groundwork for a joint NASA/ESA Mars Sample Return program. This mission would land on Mars, collect sealed tubes of Mars rocks from a rendezvous site, and bring them back to be studied on Earth. Perseverance has already taken dozens of samples in anticipation of the next part of the mission. Now, the rover also carries a piece of Cheyava Falls. If these samples make it into labs, they could give us powerful insights into whether Mars once hosted life.

“Mars Sample Return is not about returning any rock, but the right rocks. And this is one of those right rocks,” said Casey Dreier, chief of space policy at The Planetary Society.

Unfortunately, Mars Sample Return is one of many investments now threatened by devastating cuts proposed to NASA’s budget. In May, the White House’s budget office announced a plan to slash NASA science funding by 47% and cancel no fewer than 41 space missions, including spacecraft already paid for, launched, and making discoveries. That includes two current Mars missions and Mars Sample Return. Perseverance itself faces a 23% cut to operations.

“We have the ability, the know-how, and the resources to continue this search. We know where to look and how to look. Instead, the White House has proposed to unilaterally abandon this effort,” said Dreier.

Experts have called for Mars Sample Return as a top scientific priority for over 20 years. The United States and European partners have invested billions in the program already, and generations of scientists have dedicated themselves to making it a reality. 

Even before Perseverance had discovered Cheyava Falls, abandoning the samples it had collected would have been a historic mistake. Now, our best evidence for alien life may hang in the balance. Join us in calling on Congress to bring Cheyava Falls home.