The sedimentary rocks were found to contain clay and silt, along with organic carbon, sulfur, rust (oxidized iron) and phosphorus.
The samples were particularly eye-catching because they appeared to have dark black patches akin to leopard spots.
“These textural features told us that something really interesting had happened in these rocks. Some set of chemical reactions occurred at the time they were being deposited,” Joel Hurowitz, a planetary scientist at Stony Brook University in New York, said at the briefing. Hurowitz is the lead author of a new paper about the discovery that was published Wednesday in the journal Nature.
Hurowitz said the spots may be patterns of minerals left behind by microbial life-forms that had long ago consumed the organic carbon, phosphorus and other raw ingredients on the rock as an energy source.
“When we see features like this in sediment on Earth, these minerals are often the byproduct of microbial metabolisms that are consuming organic matter and making these minerals as a result of those reactions,” he added.
Carbon and phosphorus are key ingredients in molecules critical for life, including DNA.
While the research has been peer-reviewed, the findings will need extensive follow-up study to confirm or disprove the potential biosignature, NASA officials said.
Previous claims have, for instance, faced skepticism. An ancient Martian meteorite found in Antarctica in 1984 caused a stir when researchers suggested it contained microbial fossils from Mars. Later research determined that the space rock’s organic material did not have biological origins but instead formed through geological interactions between the rock and water.
For now, Hurowitz and his colleagues are limited in how much further analysis they can conduct remotely with Perseverance’s suite of instruments. But the rover mission was originally designed to gather several rock samples that would eventually be brought back to Earth on future missions for further analysis.
Those goals may be in jeopardy, however.
President Donald Trump’s budget blueprint, released in May, called for deep cuts at NASA, slashing roughly 25%, or more than $6 billion, from its budget. The proposed cuts included terminating NASA’s Mars Sample Return program, which envisioned multiple missions operated jointly with the European Space Agency to retrieve the samples collected by the Perseverance rover.
During Wednesday’s briefing, NASA’s acting administrator, Sean Duffy, said officials will review the scope of missions and their timelines before they decide the fate of the Martian samples.
“We believe there’s a better way to do this, a faster way to get these samples back,” Duffy said. “And so that is the analysis that we’ve gone through. Can we do it faster? Can we do it cheaper? And we think we can.”
Perseverance was launched to Mars in 2020 and spent more than three years exploring the floor of Jezero Crater before it made a long and steep trek to the crater’s western rim.