(ORDO NEWS) — When looking for signs of life on Mars, according to new research, we need to look for “false fossils,” which may be abundant on the Red Planet.
The Perseverance rover lists among the objectives of its mission to search for signs of life on the red planet. A robot explorer is tasked with finding signs of ancient microbial life on a dusty and dry planet – tiny fossils that could indicate Mars was once inhabited.
It would indeed be a startling, incredible discovery, but the new article calls for caution in interpreting what we find both in this and in future sources.
According to astrobiologist Sean McMahon of the University of Edinburgh and geobiologist Julie Cosmidis of the University of Oxford in the UK, scientists will have to keep track of non-biological deposits of minerals that look like fossils.
In their new article, the scientists described dozens of non-biological or abiotic processes that can produce pseudo-fossils – structures similar to the fossils of microscopic organisms that once existed on Mars.
Many physical processes associated with weathering and deposition of sedimentary layers can lead to the formation of rocks that are very similar to fossils.
Another mechanism is the chemical trace, in which the mixing of chemical elements can create structures that appear biological. Many different types of minerals can also combine to form pseudo-fossils known as biomorphs, which look strikingly biological.
Below you can see an example of chemical pseudo-fossils.
Chemical pseudo-fossils. (McMahon and Cosmides, J. Geol. Soc., 2021)
Even textures in stone can appear biological as organisms can etch out patterns or holes in the stone. And the isotope ratios of various elements can appear similar to the isotope ratios in a biological context.
Since we do not know what life could have originated on Mars – it could be very different from life here on Earth – and since, as McMahon and Cosmidis noted, there are likely many unknown processes that can produce pseudo-fossils, biologists looking life on Mars must be very careful.
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