NASA has revealed what it calls the strongest evidence so far of past microbial life on Mars.
The discovery comes from a rock sample collected by the Perseverance Rover, which shows organic signatures that scientists cannot explain without considering biology.
At a press conference on Wednesday, Acting NASA Administrator Sean Duffy said the scientific community had reviewed the findings for a year.
“In the past we thought we found signs of life, and when we put [our findings] out… the community would say there are other explanations,” Duffy explained. “This time, they can’t find another explanation.”
Nicola “Nicky” Fox, head of NASA’s Science Mission Directorate, described the finding as “the closest we’ve come to actually discovering ancient life on Mars,” though she stressed it was a leftover sign — not living organisms.
Inside the Sapphire Canyon rock
The sample, named Sapphire Canyon, was collected in July 2024 from Neretva Vallis near Jezero Crater, an area once thought to be a river system.
Scientists identified two striking features on the rock — small dark “poppy seeds” and larger “leopard spots.” Using the rover’s PIXL instrument, researchers detected G-band signals indicating organic carbon.
Joel Hurowitz of Stony Brook University, lead author of the published paper, said the rock’s mineral mix — including vivianite and greigite — often forms in the presence of microbial activity. While non-biological processes could theoretically explain it, Hurowitz admitted no abiotic scenario fits cleanly.
Why scientists are excited
The discovery is not direct proof of life but could be a “fossilized signature” of microbial activity from 3.5 billion years ago.
“This is a signature — a leftover sign — not life itself,” Fox emphasized. “It’s the equivalent of seeing fossilized waste left behind by microbes.”
Despite rigorous attempts to rule out geological explanations, researchers have yet to find a convincing non-biological cause.
Mars sample return mission in question
NASA officials stressed that conclusive answers require returning the samples to Earth. Perseverance was designed with the Mars Sample Return (MSR) program in mind, but the mission faces major budget and technical hurdles.
Project scientist Katie Stack Morgan noted that the rover has reached the limits of its instruments. “We threw the entire rover science payload at this rock. We’re close to the limits of what Perseverance can do,” she said.
Duffy, while supporting MSR, hinted at a scaled-back approach. “Continuing with missions that can’t meet budget and timing would be foolish,” he warned, though he added, “We believe there is a faster way to do this.”
While the U.S. debates funding, China has accelerated its own Mars sample mission, aiming to return rocks by 2031 — two years before NASA’s current timeline.
Duffy acknowledged the competition, saying: “We lead and we’re going to continue to lead.” But with delays and funding uncertainties, the U.S. risks falling behind in this new space race.
