According to a recent research, we should be on the lookout for ‘false fossils,’ which may be abundant on Mars, when hunting for indications of life.
Perseverance, a Mars rover, declares a first for red planet exploration as one of its mission objectives. The robotic investigator has been charged with investigating the dusty, arid planet for clues of ancient microbial life – small micro-fossils that might indicate that Mars was once habitable.
That would be a wonderful find – but the current article cautions us to be cautious in interpreting what we find in this and future sources.
Scientists will have to keep a watch out for non-biological mineral deposits that look a lot like fossils, according to astrobiologist Sean McMahon of the University of Edinburgh and geobiologist Julie Cosmidis of the University of Oxford in the UK.
The two have identified dozens of non-biological, or abiotic, processes that can yield pseudofossils — formations that resemble remains of microscopic animals that may have previously lived on Mars – in a new research.
“A Mars rover will almost probably encounter something that looks a lot like a fossil at some point,” McMahon said. “Being able to accurately separate them from structures and chemicals created by chemical processes is crucial.”
“There is at least one non-biological mechanism that makes very comparable things for every sort of fossil out there, so there is a great need to better our knowledge of how they occur.”
This idea isn’t that shocking. Pareidolia and conspiracies are in abundance on Mars. All it takes is one odd-looking pebble to start a rumour mill.
It’s not just tabloids and conspiracy theorists that have fantasised about Mars; scientists have as well. You may recall when mycologists thought they discovered mushrooms on Mars, or when an entomologist thought he discovered bugs.
As a result, microfossils might be troublesome. Even here on Earth, we have difficulty distinguishing between really old rocks and ancient microorganism fossils.
However, we have a higher chance of correctly understanding what we’re seeing if we go into the investigation of any putative microfossils on Mars knowing what mechanisms might yield pseudofossils.
Many physical processes related with weathering and sedimentary layer deposition can result in rocks that resemble fossils.
Another process is the chemical garden, in which chemicals mixed together can generate biological-looking structures. Many various forms of minerals may also be combined to form biomorphs, which resemble living pseudofossils.
Below is an illustration of chemical garden pseudofossils.
Because creatures may scratch patterns or holes into stone, even the texture of the rock might appear alive. In biological circumstances, isotope ratios of certain elements can resemble isotope ratios.
Because we don’t know what kind of life could have evolved on Mars – it could be very different from life on Earth – and because, as McMahon and Cosmidis pointed out, there are likely many unknown processes that can produce pseudofossils, biologists searching for life on Mars will have to be extremely cautious.
More research, and even experiments, into the chemistry and physics of Mars could disclose some of these undiscovered processes and give more insight on how such formations are formed, according to the researchers. This research might potentially aid our understanding of the Earth’s rock and fossil record.
“In the past, life-mimicking mechanisms have tricked us,” Cosmidis added.
“Objects that appeared to be fossil bacteria have been documented in ancient rocks on Earth and even in meteorites from Mars on several occasions, but upon closer inspection, they were discovered to have non-biological origins. This essay serves as a cautionary tale, in which we ask for more study on life-mimicking processes on Mars in order to avoid falling into the same traps again and again.”
The findings were reported in the Journal of the Geological Society.