NASA Stores Mars Rock Sample With Potential Life Signs

NASA's Perseverance rover collected the Sapphire Canyon rock sample on Mars from the Neretva Vallis region, where an ancient river once flowed into Jezero Crater more than 3 billion years ago, giving scientists a possible clue about past microbial life.

The sample, taken in July 2024 from an arrowhead-shaped rock called Cheyava Falls, contains leopard-like spots that researchers say may resemble biological activity on Earth. NASA has not confirmed the presence of life, and the sample remains stored inside the rover.

According to NASA and Perseverance team researchers, the rover has filled 33 tubes with rock, dust and atmospheric samples. The agency's original Mars Sample Return effort was halted after concerns about cost and complexity, leaving no confirmed return timeline.

"This is the first time I think we’ve found something that qualifies as a ‘potential biosignature’ on Mars" said Adrian Broz, a member of Perseverance’s science team and a postdoctoral researcher in the Planetary Surface Processes Lab at Purdue University in Indiana.

Broz said the Sapphire Canyon sample is sealed inside Perseverance and requires return to Earth for detailed laboratory analysis. The spotted patterns may have formed through microbial processes or nonbiological chemical reactions.

"When there’s organic matter that’s lodged in sediment or soil that’s buried and microbes start to digest some of that organic matter, they form these bleached halos and spots that are quite resemblant to the ones that Perseverance found in this ancient river valley," said Adrian Broz, a member of Perseverance’s science team.

NASA stated that it is reviewing alternative ways to return Perseverance samples, including possible commercial or international contributions, after reassessing the earlier Mars Sample Return plan.

"While Perseverance’s samples remain safely stored on Mars, NASA is exploring a range of potential return options that could offer simpler and more affordable approaches than the original Mars Sample Return plan, including possible commercial or international contributions," said NASA in a statement.

The scientific debate centers on whether the rock markings are true biosignatures. Researchers compare the challenge with the Allan Hills 84001 Martian meteorite, where nonbiological processes created features that were initially considered possible signs of life.

"We can keep doing these studies and coming up with these hints, but we’re never going to know for sure until we get those samples back," said Briony Horgan, professor of Earth, atmospheric and planetary sciences at Purdue University and a Perseverance team coinvestigator.

Horgan said rover instruments can provide important information but were not designed to deliver the full range of laboratory analysis needed to determine whether life existed on Mars.

"Even when you have all the labs all over the world looking at a rock that has putative evidence of ancient life, it is a really difficult thing to do, and so you want to just be able to apply every technique you can think of in all the best labs," said Ashwin Vasavada, project scientist for the Curiosity rover at NASA’s Jet Propulsion Laboratory.

Other Perseverance findings include minerals linked to past water environments. NASA's PIXL instrument identified silica, iron associated with phosphate, and carbonate in samples from Jezero Crater.

"On Earth, this fine-grained silica is what you often find in a location that was once sandy. It’s the kind of environment where, on Earth, the remains of ancient life could be preserved and found later," said Morgan Cable, deputy principal investigator of PIXL at NASA.

Scientists selected Jezero Crater because orbital images showed evidence of an ancient lake and river delta, which can preserve fossils and other geological records.

"We picked Jezero Crater as a landing site because orbital imagery showed a delta – clear evidence that a large lake once filled the crater. A lake is a potentially habitable environment, and delta rocks are a great environment for entombing signs of ancient life as fossils in the geologic record. After thorough exploration, we’ve pieced together the crater’s geologic history, charting its lake and river phase from beginning to end," said Ken Farley, Perseverance project scientist.