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Solving fossil mystery could aid search for alien life on Mars

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Probes searching for evidence of alien life on Mars may have an easier task in future thanks to new research which shows that certain organic-like forms found in rock structures are not the result of microcellular organisms.

On Mars, the time and resources of probes sent there are precious and anything to help them avoid analysing unnecessary data will be valuable to future missions.

A team from the University of Edinburgh has shown that microscopic tubes and filaments that resemble the remains of tiny creatures may actually have been formed by chemical reactions involving iron-rich minerals.

Previous research had suggested that such structures were among the oldest fossils on Earth.

The discovery was made by astrobiologist Sean McMahon, who is developing techniques to seek evidence that life once existed on Mars.

He created tiny formations in the lab that closely mimic the shape and chemical composition of iron-rich structures commonly found in Mars-like rocks on Earth, where some examples are thought to be around four billion years old.

McMahon created the complex structures by mixing iron-rich particles with alkaline liquids containing the chemicals silicate or carbonate.

This process - known as chemical gardening - is thought to occur naturally where these chemicals abound. It can occur in hydrothermal vents on the seabed and when deep groundwater circulates through pores and fractures in rocks.

His findings suggest that structure alone is not enough to confirm whether microscopic life-like formations are fossils. More research will be needed to say exactly how they were formed.

“Chemical reactions like these have been studied for hundreds of years but they had not previously been shown to mimic these tiny iron-rich structures inside rocks. These results call for a re-examination of many ancient real-world examples to see if they are more likely to be fossils or non-biological mineral deposits,” McMahon said.

In June, speculation about possible life on Mars was reignited due to the detection of methane spikes which can suggest the presence of microbial life.

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