A long time ago, life left microscopic signatures on Mars — or did it? That's the question NASA scientists have worked for years to answer. On Wednesday, NASA researchers said the answer might be in a rock sample that "contains potential biosignatures."
The finding, published Wednesday in the journal Nature, puts the agency one step closer to answering one of humanity's most profound questions about life in the universe, said Nicky Fox, associate administrator of NASA's science mission directorate.
"This finding by our incredible Perseverance rover is the closest we've actually come to discovering ancient life on Mars. And if you can't tell, we're really excited about that," Fox said during a news conference at NASA's headquarters in Washington.
The exciting rock sample in question is dubbed Sapphire Canyon. NASA's Perseverance Mars rover collected it last summer from a reddish, vein-filled rock along the edge of an ancient, quarter-mile wide river valley known as Neretva Vallis.
The valley was carved by water flowing into the large Jezero Crater, which also held a lake billions of years ago.
"Jezero was selected because it's in a location amongst the most ancient terrains on Mars, exposing some of the oldest rocks anywhere in the solar system," said Katie Stack Morgan, Perseverance project scientist at NASA's Jet Propulsion Laboratory in Southern California.
"These really ancient rocks provide us a window into a period of time that's not particularly well represented on our own planet Earth," she added. "But it's a time when life was emergent on Earth, and could have been on Mars as well."
Perseverance landed in the crater in early 2021, with the goal of collecting and analyzing samples that would let researchers study an ancient river delta — identified as a potentially rich source of signs of ancient microbial life.
Then, in July 2024, Perseverance found the rock that has tantalized scientists for months. NASA researchers say it has features such as small black "poppy seed" spots and larger "leopard spots" — patterns that are often telltale signs associated with life.
"This is the kind of signature that we would see that was made by something biological," Fox said. "In this case, it's kind of the equivalent of seeing leftover fossils … leftovers from a meal. And maybe that meal has been excreted by a microbe. And that's what we're seeing in this sample."
Researchers using the rover's equipment to analyze the rock's spots and dots found minerals containing iron, phosphorus and sulfur, a Perseverance scientist and lead author of the study, Joel Hurowitz of Stony Brook University in New York, said at Wednesday's news conference.
What's exciting is that a combination of mud and organic matter has reacted to produce these minerals and these textures, Hurowitz said.
"When we see features like this in sediment on Earth," Hurowitz explained, "these minerals are often the byproduct of microbial metabolisms that are consuming organic matter and making these minerals as a result of those reactions."
But, he added, there are also "nonbiological ways to make these features that we cannot completely rule out" as the cause with the current data, such as being heated to extremely high temperatures.
The next big step, Hurowitz and others at the NASA event said, would be to analyze these rocks further — and in person. It would be the first time a pristine piece of another planet would be brought to Earth.
Bringing the core sample back, NASA researchers wrote in the Nature paper, would let them analyze it with specialized, highly sensitive instruments that would "determine the origin of the minerals, organics and textures it contains."
Perseverance has collected 30 samples on Mars so far, according to NASA, with six empty tubes left unfilled. But the agency is still working on a plan to bring them back.
NASA previously laid out plans to land a spacecraft carrying Martian specimens at a U.S. Air Force testing range in Utah. But such a mission would cost billions and take years to complete — and in May, President Trump proposed cutting funding for the Mars Sample Return program, calling it "financially unsustainable." Earlier this year, the agency said it was weighing two different options for how to land and load the samples from Mars' surface.
"We believe there is a better way to do this, a faster way to get these samples back," acting NASA Administrator Sean Duffy said on Wednesday.
Duffy also said that NASA remains committed to crewed missions exploring space, as part of its scientific pursuits.
"So what we do on Mars," he added, "these missions help us in what we're going to do in the future as we do go back to the moon and eventually get to Mars."
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