NASA studies Scottish rocks to interpret possible signs of ancient life on Mars

NASA scientists have collected rocks from Scotland’s Stoer formation to investigate how features resembling spots seen by the Perseverance rover on Mars can form. The samples are now back in laboratories for analysis, NASA said on September 29. The work could help researchers interpret the rover’s observations, but NASA has reported no results from the Scottish samples and no finding of life on Mars.

The Goddard Instrument Field Team worked along the coast of the Scottish Highlands during summer 2026, including in the Clachtoll region and at the Bay of Stoer. NASA said the trip followed questions raised by Perseverance’s observations in Jezero Crater. Its account gives no more precise date for the fieldwork.

Why the Stoer rocks matter

According to NASA, rocks in the Stoer formation formed in settings comparable to ancient Martian lakes and rivers. NASA dates evidence of microbial life in the Scottish formation to about 1.2 billion years ago, before land plants existed. That combination gives researchers terrestrial rocks in which to examine how traces of past life can survive in sediments resembling those once shaped by water on Mars.

The feature drawing particular attention is a gray-green reduction spot in otherwise reddish rock. Such spots mark chemical changes and can sometimes reflect ancient microbes interacting with the rock, NASA said. They can also form by other processes. Finding a spot is therefore a reason to investigate its chemistry and setting, rather than a conclusion about its origin.

The expedition was led by the Goddard team, with collaborators from NASA’s Johnson Space Center, the University of Glasgow, the University of Maryland, Purdue University, Stony Brook University and the University of Cambridge. NASA describes the work as planetary analog research: studying Earth environments to help interpret landscapes on other worlds.

What Perseverance saw on Mars

The Scottish trip follows an earlier observation in Jezero Crater. In July 2024, NASA’s Jet Propulsion Laboratory reported that Perseverance had examined a reddish rock called Cheyava Falls, near the northern edge of Neretva Vallis, an ancient river valley that carried water into the crater. The rover collected a sample there on July 21, 2024.

JPL described millimeter-scale pale spots ringed with dark material in Cheyava Falls. Perseverance’s PIXL instrument detected iron and phosphate in the rings. Rover instruments also detected organic compounds in the rock, although JPL cautioned that such compounds can form without biology. The agency presented the rock as intriguing evidence requiring further study, with other explanations still under consideration.

Perseverance scientist Ken Farley told JPL that the team had not established exactly how Cheyava Falls formed or whether nearby rocks had heated it. He said laboratory examination of a returned sample would help resolve the rock’s history. The observations on Mars thus raise a question that instruments on the rover have not settled.

What experiments can show

A separate, peer-reviewed study published in June 2026 provides one reason to test the spots carefully. Sev Zielinska and colleagues reported that millimeter-to-centimeter bleached reduction spots formed within weeks in laboratory sediment containing iron and inoculated with microbial communities. Spots did not form in the study’s sterile controls; the authors said the pattern of spots and their DNA results supported microbial formation under those experimental conditions.

That experiment does not identify the cause of the spots in Scotland or on Mars. The study’s authors called for further experiments to determine whether non-biological processes can mimic the spots and which features might distinguish the two origins. NASA likewise cautions that reduction spots in the Stoer rocks can form in more than one way.

The laboratory finding supplies a possible microbial mechanism for researchers to examine, while the Scottish field samples offer natural rocks whose surrounding geology can also be studied. Neither finding establishes that Martian spots were made by microbes. The distinction matters because similar-looking marks can carry different histories, and the origin of a feature cannot be settled by appearance alone.

Analysis still ahead

NASA said scientists in laboratories in the United States and elsewhere are preparing deeper chemical and mineral analysis of the Scottish samples using tools that could not be carried into the field. Its September 29 account does not give a schedule for that work or report completed laboratory results.

The agency says the follow-on research is intended to improve interpretation of Mars rover data, guide possible new rover investigations and prepare scientists for potential future analysis of Martian samples. For now, the Scottish expedition has supplied material for those tests, while the origin of Perseverance’s spots and the question of ancient life on Mars remain unresolved.