Scientists believe intriguing leopard spots on a rock sampled by the Perseverance rover on Mars last year may have potentially been made by ancient life, NASA announced Wednesday. The team has also published a peer-reviewed paper in the journal Nature about the new analysis, though they say further study is needed.
“After a year of review, they have come back and they said, listen, we can’t find another explanation,” said Acting NASA Administrator Sean Duffy. “So this very well could be the clearest sign of life that we’ve ever found on Mars, which is incredibly exciting.”
The sample, called Sapphire Canyon, was collected by the Perseverance rover from rocky outcrops on the edges of the Neretva Vallis river valley, a region sculpted by water that once flowed into Jezero Crater more than 3 billion years ago. The rover landed within the crater to explore the ancient lake site in February 2021, seeking rocks created or modified by water on Mars in the past.
Perseverance drilled the Sapphire Canyon sample from an arrowhead-shaped rock called Cheyava Falls in July 2024.
Although the sample is safely ensconced in a tube millions of miles away on Mars, scientists have remained intrigued by the rock because of its potential to reveal whether microscopic life ever existed on Mars.
“The discovery of a potential biosignature, or a feature or signature that could be consistent with biological processes, but that requires further work and study to confirm a biological origin is something that we’re sharing with you all today that grows from years of hard work, dedication and collaboration between over 1,000 scientists and engineers here at the (NASA) Jet Propulsion Laboratory and our partner institutions around the country and internationally,” said Katie Stack Morgan, Perseverance project scientist at JPL, during a news conference Wednesday.
Shortly after the rock was found, members of the Perseverance science team said it was exactly the type of rock they were hoping to find. NASA initially shared the Cheyava Falls rock discovery at the end of July 2024.
The new announcement Wednesday is the result of a long, peer-reviewed research process and the collection of more data, said lead study author Joel Hurowitz, a planetary scientist at Stony Brook University in New York.
Peer review and publication are crucial steps in the scientific process that allow NASA to make the mission data and the science team’s interpretation of that data available to the broader science community for further study, said Lindsay Hays, senior scientist for Mars Exploration at NASA’s Planetary Science Division.
“Hopefully, eventually this will be followed by the delivery of these samples back to Earth where they could be studied in terrestrial labs,” Hays added.
Perseverance rover surveyed the river valley after finding the sample to better understand the environment where the rocks were deposited and determine how the leopard spots may have formed, Hurowitz said.
Understanding exactly how those spots came to be — whether through geochemical processes that don’t require life, or due to the presence of microbial life — is a crucial step in determining whether the rock contains evidence of a potential biosignature.
“Today, we are really showing you how we are kind of one step closer to answering humanity’s, one of their most profound questions, and that is, are we truly alone in the universe?” said Nicky Fox, associate administrator for NASA’s Science Mission Directorate.
Cheyava Falls, named for one of the Grand Canyon’s waterfalls, showcased small black spots nicknamed “poppy seeds” by Perseverance’s science team, as well as larger markings dubbed leopard spots.
The rover’s SHERLOC instrument, or Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals, also detected organic compounds in the rock.
On Earth, these carbon-based molecules are the building blocks of life. The mottling could indicate that ancient chemical reactions occurring within the rock once supported microbial organisms.
White veins of calcium sulfate present clear evidence that water — crucial for life — once ran through the rock. And the irregular-shaped leopard spots, tested by the rover’s PIXL instrument, short for Planetary Instrument for X-ray Lithochemistry, detected iron and phosphate within the features.
The team also spotted the potential presence of hematite between the white bands of calcium sulfate in the rock. Hematite is one of the minerals responsible for Mars’ signature red hue. The leopard spotting may have occurred when chemical reactions with hematite turned the rock from red to white, which can release iron and phosphate and potentially cause the black rings to form. Such reactions can also provide an energy source for microbes.
Cheyava Falls may have begun as a mixture of deposited mud and organic compounds that eventually cemented to become rock. Later on, water may have penetrated through cracks in the rock, depositing minerals to create the calcium sulfate veins and leopard spots.
Since landing on Mars, Perseverance has crossed Jezero Crater and explored an ancient river delta in search of microfossils of past life. The rover has been collecting samples along the way that were intended to be returned to Earth by future missions. But it’s currently unclear how NASA would return the samples to Earth as the agency grapples with the White House’s proposal to slash NASA’s science budget by as much as half.
“We’re looking at how we get the sample back, or other samples back,” Duffy said. “What we’re going to do is look at our budgets, we look at our timing, and you know, how do we spend money better, and you know, what technology do we have to get samples back more quickly? And so that’s a current analysis that’s happening right now.”
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