Why NASA is studying 1.2-billion-year-old Scottish rocks for clues to ancient life on Mars and the Red Planet’s watery past

A rugged stretch of Scotland’s northern coast is helping NASA investigate one of planetary science’s biggest questions: Did Mars ever support life?

The rocks being studied are not from Mars.

They belong to the Stoer Formation in the Scottish Highlands, where some rocks formed around 1.2 billion years ago in environments shaped by water. They also preserve evidence associated with ancient microbial life, from a time long before plants transformed Earth’s land surface.


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That combination makes the region a useful natural laboratory for NASA scientists.

Scientists are looking into how fossils from the distant past form in rocks and how these signs can be separated from the chemical signs that can be formed through common geology. This information could assist scientists in analyzing data gathered by NASA’s Perseverance Rover at Jezero Crater on Mars.

Perseverance has already encountered rocks containing features that scientists describe as potential biosignatures. But potential does not mean confirmed evidence of life. The same minerals and chemical patterns can sometimes form without biological activity.

That is why NASA researchers travelled to Scotland.

Why Scotland looks useful for Mars research

Mars looks nothing like the wet and windswept Scottish Highlands today.

However, billions of years ago, Mars had rivers, lakes, and other areas where water flowed and remained there for a period of time.

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The Jezero Crater, where the rover landed in 2021, was a place where there used to be a lake with a river system. The sediments got deposited here and made layers of rocks.

Earth has its own record of ancient water-rich environments.

The Stoer Formation preserves rocks that formed around 1.2 billion years ago, offering scientists an opportunity to study how ancient sediments can retain evidence of microbial activity over immense periods.

This type of research is known as planetary analogue research. Scientists study a location on Earth that shares important geological or environmental characteristics with another world.

The objective is not to suggest that Scotland and Mars are identical. Instead, researchers can use Earth's better-preserved geological record to answer questions that are difficult to investigate directly on Mars.

If microbial organisms alter minerals or leave chemical traces in Earth's rocks, scientists can examine what those signatures look like after billions of years of geological change.

They can then compare those observations with what Mars rovers detect.

That comparison is particularly useful because rover instruments have limitations. Although Perseverance carries sophisticated equipment, scientists on Earth have access to much larger laboratories and a wider range of analytical techniques.

The ancient rocks preserve clues about microbial life

The age of the Scottish rocks is a major part of their value.

Around 1.2 billion years ago, microbial life was already established on Earth, but the planet's land surface looked dramatically different from today. Complex land plants had not yet become widespread.

The rocks therefore preserve a record from a very different stage in Earth's history.

It is also very interesting to study the interaction between microorganisms and their environment. Any biological process can modify the chemical composition of the sediments and lead to mineral genesis or modification. Such modifications may persist even after all organisms die.

But there is a major complication.

Geology can imitate biology.

Some minerals associated with microbial processes can also form through non-biological chemical reactions. A chemical pattern that looks promising may therefore have nothing to do with life.

That distinction lies at the heart of the Mars investigation.

NASA's Perseverance rover found the rock Cheyava Falls in Jezero Crater, where scientists identified distinctive mineral patterns alongside organic material. NASA has described these characteristics as a potential biosignature, but researchers have not concluded that they were produced by Martian organisms.

The Scottish rocks offer a way to investigate that problem using material from an environment where scientists have much more information.

NASA scientists climbed Scottish cliffs to collect samples

The research required more than examining photographs or geological maps.

Scientists from NASA's Goddard Instrument Field Team travelled to the Clachtoll region of the Scottish Highlands and worked along the coast and cliffs.

Fieldwork had to be carefully timed. Some investigation areas could only be reached safely between high tides, while the wet Scottish climate created additional challenges on the steep terrain.

Researchers carried handheld scientific instruments into the field to examine the rocks' mineral and chemical composition.

They also studied the surrounding geology to understand the environments in which the rocks formed. Selected samples were collected and transported for more detailed laboratory analysis.

That two-stage approach is important.

Measurements taken in the field provide immediate information about the rock and its surroundings. Laboratory equipment can then investigate the samples in much greater detail.

Scientists can examine mineral structures, chemistry and possible traces of ancient biological activity using instruments that are far too large or complex to send to Mars.

The resulting data can help researchers build a better reference for interpreting observations made by Perseverance.

Perseverance’s mysterious rock is driving the investigation

The Scottish expedition is closely connected to one of Perseverance's more intriguing discoveries.

The rover encountered Cheyava Falls, a reddish rock in the Bright Angel formation of Jezero Crater. The rock contains unusual features that NASA scientists have described as “leopard spots”.

The spots contain iron phosphate minerals and occur alongside organic carbon and other chemical components. On Earth, combinations like these can sometimes be associated with microbial activity.

But scientists have not declared the discovery evidence of life.

There are alternative explanations for the chemistry. Certain geological processes can produce similar minerals and patterns without organisms being involved.

Determining which explanation is correct requires more evidence.

Scientists need to understand the rock's geological history, the chemistry of fluids that may have passed through it and the environmental conditions under which its minerals formed.

This is where analogue research becomes useful.

By studying ancient Earth rocks containing known evidence of microbial activity, researchers can examine what biological signatures look like after geological processes have altered them.

They can also study rocks where similar-looking features developed through non-biological processes.

That comparison could help scientists decide which Martian observations deserve the closest attention.

The research could prepare scientists for future Mars samples

The Scottish work has implications beyond Perseverance's current observations.

The rover is collecting and storing rock and soil samples that could potentially be returned to Earth for detailed laboratory study. Those samples could eventually allow researchers to use instruments far more powerful than anything that can be placed on a rover.

Preparing for that possibility requires knowing what scientists should look for.

Ancient Scottish rocks provide one part of that preparation. Researchers can test techniques on Earth, compare biological and geological signatures and investigate how traces of ancient organisms survive in old rocks.

The project involves researchers from NASA's Goddard Space Flight Center and Johnson Space Center, along with scientists from the University of Glasgow, University of Maryland, Purdue University, Stony Brook University and the University of Cambridge.

Their work could help future Mars missions identify promising locations, refine rover investigations and determine which samples deserve detailed analysis.

For now, the question of whether Mars ever hosted life remains open.

Perseverance has found evidence that ancient Mars once had environments where water was present, and it has identified rocks containing potentially interesting chemical signatures. But NASA stresses that a potential biosignature is not proof of ancient life.

The Scottish rocks cannot settle that question.

What they can provide is something scientists badly need: a known Earth-based example of how ancient life can leave traces in rocks, and how those traces can be confused with ordinary geology.

That knowledge could become increasingly important as researchers continue looking for signs of life on Mars.

Frequently asked questions

1. Why is NASA studying Scottish rocks for Mars research?

The Stoer Formation contains ancient rocks formed in water-influenced environments and preserves evidence associated with microbial life. Scientists are using the region as a planetary analogue to understand how potential biosignatures can be preserved.

2. How old are the Scottish rocks?

The rocks being studied formed around 1.2 billion years ago, when microbial life existed on Earth, but complex land plants had not yet become widespread.

3. What potential biosignature did Perseverance find?

Perseverance discovered unusual mineral patterns in the Cheyava Falls rock in Mars' Jezero Crater. The features could have a biological origin, but NASA says they are not proof that life existed on Mars.

4. How could this research help future Mars missions?

Studying ancient Earth rocks allows scientists to test how biological and non-biological processes produce similar chemical and mineral signatures. The results could help researchers interpret rover observations and analyse Martian samples if they are eventually returned to Earth.