False fossils may mislead the search for life on Mars

As the search for life on mars continues, formations taking on a similar appearance to fossils have been found.

Unfortunately, they were likely created by various non-biological chemical processes mimicking biological sources. The processes that created these false fossils produce deposits that resemble bacterial cells and carbon-based molecules.

During a period are 3.6 to 4 billion years ago, Mars would have been habitable for some life, as valleys and sedimentary rocks on the surface indicate water was once widely available. Despite this, concrete evidence of life has yet to be discovered.

In reviewing the current research, astrobiologists of the Universities of Edinburgh and Oxford noted that identifying evidence of ancient life on Mars relies on distinguishing between these false fossils and any real ones. They call for more interdisciplinary research into how these fossil-like specimens occur in an attempt to disambiguate them from genuine evidence of life.

"At some stage, a Mars rover will almost certainly find something that looks a lot like a fossil, so being able to confidently distinguish these from structures and substances made by chemical reactions is vital. For every type of fossil out there, there is at least one non-biological process that creates very similar things, so there is a real need to improve our understanding of how these form," said Dr. Sean McMahon, Chancellor's Fellow in Astrobiology at the University of Edinburgh's School of Physics and Astronomy.

The Mars 2020 Perseverance Rover is currently on Mars, searching for signs of ancient microbial life. Equipped with a drill, it will collect Martian rock and soil samples, storing them in sealed tubes aboard the rover, awaiting the day it is retrieved and brought back to Earth to be studied.

"We have been fooled by life-mimicking processes in the past. On many occasions, objects that looked like fossil microbes were described in ancient rocks on Earth and even in meteorites from Mars, but after deeper examination, they turned out to have non-biological origins. This article is a cautionary tale in which we call for further research on life-mimicking processes in the context of Mars so that we avoid falling into the same traps over and over again," said Julie Cosmidis, Associate Professor of Geobiology at the University of Oxford.

You can read more from an earlier study here.