False fossils could help search for Martian life

False fossils could help search for Martian life
Microscopic structures created in the lab
Microscopic structures created in the lab
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Microscopic structures created in the lab
Microscopic structures created in the lab

Research at the University of Edinburgh could make the search for life on Mars more efficient. Using a technique called "chemical gardening," astrobiologist Sean McMahon has demonstrated that some ancient fossils may not be the remains of living organisms, but natural mineral deposits instead. This could allow future explorers to pursue more promising avenues in finding signs of life on the Red Planet.

Based on what we've learned about Mars and its ancient past, the most likely evidence of life there will be fossils of individual microbes or their colonies. These often present themselves in the geological records as mineral formations that show a branching non-crystalline structure, hollow and circular cross-sections, layering, and other clues.

However, according to McMahon, there are microscopic tubes and filaments that look like organisms but are actually produced by very simple chemical reactions involving iron-rich minerals. If this is the case, then the search for life on Mars could be saved from chasing down some very expensive false leads.

In a laboratory environment, McMahon combined iron-rich particles with alkaline liquids containing silicates or carbonates. These produced tiny, complex formations that have a very similar shape and chemical composition to iron-rich structures found in Mars-like rocks on Earth.

This sort of chemical gardening is also found in places like the hydrothermal vents on seabeds. The question now is whether some fossils can be confirmed as being chemical rather than biological.

"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," says McMahon. "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."

The study was published in the journal Proceedings of the Royal Society B.

Source: University of Edinburgh

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