Mars could also be lined in dozens of various nonbiological “false fossils,” which might intervene with the seek for life on the Red Planet, two researchers say.
NASA’s Perseverance rover touched down on Mars in February, and the European Space Agency (ESA) will launch the Rosalind Franklin rover in 2022. Both will scour the Martian floor for biosignatures — traces of previous life — left behind from round 4 billion years in the past, when the planet might have been liveable.
However, a brand new paper suggests a attainable complication in that search.
Related: 6 reasons astrobiologists are holding out hope for life on Mars
“There is a real chance that one day, we will observe something on Mars that looks really biological, only to realize several years later, after further research, that this thing was actually formed by nonbiological processes,” co-author Julie Cosmidis, a geobiologist on the University of Oxford in England, advised Live Science.
Cosmidis teamed up with Sean McMahon, an astrobiologist at The University of Edinburgh in Scotland, to itemize these potential false biosignatures earlier than the rovers discover them.
False positives
A biosignature will be proof of both an organism itself or any product it creates. By definition, such biosignatures cannot be made by pure bodily or chemical processes. For a long time, astrobiologists have recognized biosignatures on Earth to be able to acknowledge potential types of primitive life on different worlds.
But this hunt for biosignatures has a significant limitation. “We are so good at spotting life that we see it even when it isn’t there,” McMahon advised Live Science.
Specifically, many issues that appear like biosignatures at first look can be created with out life.
“The range of structures, materials and chemical compositions that can be produced nonbiologically overlaps quite closely with the range of things that can be produced biologically,” McMahon stated. “Some phenomena have been debated for decades, and we’re still not sure if they’re biological or not.”
Paleontologists have typically been confused by these pretend fossils, Cosmidis stated. Evidence of historic bacteria and different single-celled organisms, like algae, will be particularly difficult to determine.
In 1996, scientists claimed to have discovered fossils of microscopic organisms in a Martian meteorite. Their discovery was hailed as the primary proof of alien life and even prompted a speech from President Bill Clinton. However, additional checks revealed that these fossils have been utterly abiotic, which means they weren’t made by life-forms.
On Mars, this confusion might be much more problematic as a result of scientists will not be capable of check samples correctly till they’re returned to Earth, which means it might take years to vet the Martian samples.
“The problem is that these false biosignatures are often disproved only after further analysis by different researchers, using different techniques,” Cosmidis stated. “But for Mars, we won’t have this option” till years after the samples get collected.
Potential biosignatures
“There is a wide diversity of potential false biosignatures on Mars,” Cosmidis stated.
One of the most effective examples is carbon-sulfur biomorphs — tiny spheres, “similar in size to bacteria,” that may kind spontaneously from reactions between carbon and sulfide, Cosmidis stated. Both of those reactants might have been considerable on historic Mars, and the ensuing biomorphs would additionally “fossilize very well in rock types that are common on Mars,” she added.
“If one day we find microscopic organic filaments and spheres in Martian rocks, it will be very tempting to interpret them as fossil bacteria, but they could very well just be carbon-sulfur biomorphs,” Cosmidis stated.
Another instance are pseudo-microbialites, which mimic bodily buildings created by microbes, akin to stromatolites — that are giant buildings left behind by photosynthetic algae that develop upward as cones, domes and columns. Such buildings might be left behind from marine life in Mars’ previous oceans, however near-identical buildings may kind naturally with none microbes so will probably be laborious to inform if they’re real.
McMahon and Cosmidis recreated beforehand identified false biosignatures in Martian circumstances and tried to provide you with new examples not but encountered on Earth. In total, they listed greater than a dozen potential pretend fossils of their new paper, however many extra could also be on the market.
The researchers hope their work will assist to stop an faulty discovery and the ensuing disappointment, which might undermine a long time of labor within the seek for alien life.
“These errors and their corrections are a normal process in science,” Cosmidis stated. “But on a topic that is receiving as much attention from the public as the search for life on Mars, there is a risk that they could generate public mistrust in scientists.”
However, regardless of their warning, the researchers say that they’re totally dedicated to the seek for life on Mars.
“We are not trying to dismiss all the efforts that NASA and ESA are currently putting into finding traces of life on Mars,” Cosmidis stated. “We want to support these efforts by helping the researchers involved in these missions make better and more informed interpretations of the objects they will observe.”
The paper was printed on-line Nov. 17 within the Journal of the Geological Society.
Originally printed on Live Science.
