When looking for signs of life MarsWe need to look for ‘pseudofossils’ that may be abundant on the Red Planet, according to a new study.
The Mars probe lists, among its mission objectives, the first of its kind to explore the Red Planet. The robotic explorer has been tasked with searching for signs of ancient microbial life on the dry, dusty planet — minute fossils believed to be evidence that Mars was once habitable.
It would indeed be a startling and unbelievable discovery – but the new article calls for caution in interpreting what we find, both in this source and in future sources.
According to astrobiologist Sean McMahon of the University of Edinburgh and geologist Julie Cosmides of the University of Oxford in the UK, scientists will need to monitor deposits of non-biological minerals that closely resemble fossils.
In a new article, the pair describe dozens of non-biological or abiotic processes that can produce pseudofossils — structures that resemble the fossils of microscopic organisms like those that may have existed on Mars.
“At some point, the Martian spacecraft will find something very similar to a fossil, so it is essential to be able to confidently distinguish them from structures and materials resulting from chemical reactions,” he added. McMahon said.
“For every type of fossil, there is at least one non-biological process that creates very similar things, so there is a real need to improve our understanding of their formation.”
This idea is not really surprising. March is an absolute holiday for pareidolia and intrigue. All you need is a funny looking rock and rumors are circulating.
It’s not just tabloids and conspiracy theorists – scientists have also indulged in Martian fantasies. You might remember the time mycologists thought they found fungi on Mars, or the entomologist who thought they found insects.
So microfossils can be a big problem. Even here on Earth, we find it difficult to tell the difference between very old rocks and fossils of ancient microbes.
But, if we go to analyze any possible microfossils on Mars with knowledge of the processes that can produce pseudofossils, we have a better chance of accurately interpreting what we’re seeing.
Many physical processes associated with weathering and deposition of sedimentary layers can produce rocks that look strangely like fossils.
Another mechanism is chemical gardenMixing chemicals can produce structures that appear biological. Many different types of minerals can also combine to produce pseudofossils called biomorphic, which looks surprisingly organic.
You can see an example of chemical garden pseudofossils below.
Even rocky textures can appear organic, as organisms can carve patterns or holes in the stone. The isotopic ratios of different elements may appear similar to isotopic ratios in biological contexts.
Since we don’t know what kind of life may have arisen on Mars – it may be very different from life here on Earth – and since, as McMahon and Cosmides note, there are likely many unknown processes that can produce pseudofossils and life-seeking biologists On Mars to be very careful.
The researchers also note that further work, and possibly even experiments, on the chemistry and physics of Mars could reveal some of these unknown processes and shed light on how to produce such formations. This work could even help us better understand Earth’s rocky and fossil records.
“We’ve been fooled in the past by life simulations”, Cosmidis . said.
“On numerous occasions, objects resembling fossil microbes have been described in ancient rocks on Earth and even in meteorites from Mars, but upon closer examination, they have been shown to have non-biological origins. This article is a cautionary tale in which we call for further research into simulations of life in the context of Mars, in order to avoid falling into the same traps over and over again.”
The search was published in Journal of the Geological Society.
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