Mars researchers looking for signs of ancient life may have been misled by fossil-like specimens created by chemical processes, researchers say.
Mars researchers looking for signs of ancient life may have been misled by fossil-like specimens created by chemical processes, researchers say.
Rocks on Mars may contain many types of non-biological deposits that look similar to fossils of the type likely to be found if they ever lived on the planet, the study said.
The ability to distinguish between these imaginary fossils and what could be evidence of ancient life on Mars – which was temporarily populated four billion years ago – is essential to the success of current or future missions, the researchers say.
Astrobiologists from the Universities of Edinburgh and Oxford examined evidence of all known processes that could have formed life-like deposits in rocks on Mars.
They have identified dozens of processes – and there are likely many more that have not yet been discovered – that can create structures that mimic structures of simple microscopic life forms that may have once existed on Mars.
Among the life-form specimens that these processes can create can be found deposits that look like bacterial cells and carbon-based molecules that are very similar to the building blocks of any known life form.
Non-living processes can mimic approximately many signs of life, so the source of any fossil-like specimen found on Mars will probably be very ambiguous, the team says.
They call for more multidisciplinary research to better understand how life-like deposits can form on Mars, thus helping to search for evidence for the existence of ancient life there and elsewhere in the solar system.
The study is published in the Journal of the Geological Society.
Dr Sean McMahon, an astrobiologist from the University of Edinburgh School of Physics and Astronomy, said: “At some point a Martian vehicle will almost certainly find something that looks very much like a fossil, so the ability to confidently differentiate between these and structures and materials created by chemical reactions is essential. For every type of fossil found 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 are formed. “
Julie Cosmidis, an associate professor of geobiology at Oxford University, said: “Life-imitating processes have deceived us in the past. In many cases, objects that looked like fossilized bacteria have been described in ancient rocks on Earth and even on Martian meteorites. This is a warning sign through which we call for further investigation of life-imitating processes in the context of Mars, so that we avoid falling into the same traps over and over again. “
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