For four years, NASA’s Perseverance rover has searched for possible signs of ancient life on the surface of Mars. It has found myriad interesting features in its travels, including a rock with strange spots, discovered inside Mars’ Jezero Crater. Dubbed “Cheyava Falls,” the 2024 discovery immediately caught the attention of scientists on Earth, as its spots indicated it may hold a potential biosignature—a sign of life.
The rover went to work. The bot analyzed the rock’s composition and surface chemistry, and then extracted a core nicknamed “Sapphire Canyon.”
It’s hard work has seemingly paid off. On Wednesday, NASA scientists dropped the bombshell: Cheyava Falls may in fact be the clearest sign of past life ever found on Mars.
“We had almost left the crater. These were the last set of sedimentary rocks we were probably going to be looking at on the mission,” Joel Hurowitz, a planetary scientist at Stony Brook University, told Gizmodo. He is the lead author on a new study detailing the findings that was published in Nature.
“It was super surprising that this would have been the place where the potential biosignatures jumped out of the rock at us and said, ‘hey, look here!’”
Of the 30 rock and regolith samples Perseverance has collected over the last four years, none show more promise as evidence for ancient life on Mars than this one. But actually confirming a biosignature depends on getting this sample back to Earth. At stake is one of the most enduring questions of our world: Is life on Earth truly alone?
“I don’t think we’re ever going to make that determination without that sample in our hands,” Hurowitz said.
The case for a potential biosignature
The surface of Cheyava Falls bears tiny black spots that NASA scientists describe as like “poppy seeds,” interspersed among larger “leopard” spots. These features suggested to Hurowitz and his colleagues that chemical reactions had occurred at the time these sediments were deposited.
Perseverance’s analysis found that Cheyava Falls is rich in organic carbon, sulfur, oxidized iron (rust), and phosphorus. This combination of chemical compounds could have provided a potential energy source for ancient microbes, but the researchers decided to probe the rock further.
Using Perseverance’s PIXL (Planetary Instrument for X-ray Lithochemistry) instrument to map the rock’s surface chemistry, they uncovered a distinct pattern of minerals arranged into reaction fronts—points of contact where chemical and physical reactions occur—that corresponded to the leopard spots. These spots also carried signatures of iron-rich minerals, vivianite and greigite.
On Earth, these minerals are often byproducts of reactions that arise from microbes metabolizing organic matter, according to Hurowitz. Importantly, it’s also possible that the spots on Cheyava Falls formed through some other process, for example, through geothermal heating during the early stages of the rock’s formation. “But there’s no real, clear evidence that the rocks were heated to a significant degree,” Hurowitz said.
Researchers are a long way from ruling out those possible explanations—140 million miles away, on average, in fact.
“Deciding between life‑driven and purely chemical origins needs laboratory analyses of the cored sample Sapphire Canyon,” Mario Parente, an associate professor of electrical and computer engineering at UMass Amherst, told Gizmodo. Parente was not involved in the study, but co-authored a corresponding viewpoint about the results.
Why Sapphire Canyon must return to Earth
Lab-based analyses are “essential” to answering key questions that could confirm whether this is, indeed, a potential biosignature, Parente said. Techniques such as nanoscale mineral identification and high-resolution chemical mapping of the Sapphire Canyon sample could determine whether it truly contains vivianite, greigite, and carbon closely interwoven with those minerals, he explained.
Additionally, isotopic analysis would be able to uncover patterns called “fractionations” that are tell-tale signs of microbial activity. “Isotopes are one of the clearest ways to separate biology from geology,” Parente said. “I think those measurements could probably answer the question pretty clearly,” Hurowitz concurred.
There is, however, a major obstacle in the way of such an endeavor: As things stand, NASA has no solid plans to go to Mars to retrieve Sapphire Canyon—or any of Perseverance’s samples for that matter. The agency has been working with the European Space Agency to develop a multi-mission Mars Sample Return campaign to retrieve the samples, but escalating costs and complexity have stalled its progress.
The White House’s budget proposal for fiscal year 2026, released in May, threatened to cut the effort’s funding, but in July, the House Appropriations Commerce-Justice-Science subcommittee moved to allocate $300 million to the program. That bill is still in process, and it remains entirely possible that the missions could be canceled.
“I would hate to see us not return the samples,” Hurowitz said. After spending more than 20 years working on Mars rover missions, he lays out what is at stake: “It’s been this incredibly well-laid-out program of exploration to get to this goal of trying to understand whether or not Mars was ever inhabited,” he said.
“With the data we have from the rover, we’re going to have this tantalizing clue that says, ‘maybe,’ but we can’t answer the question.”
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