When it comes to looking for evidence of signs of life on the Red Planet, humans have been able to place a land rover for the pursuit of science. However, despite the hardships surpassed by successfully landing the martian rover, there are still some problems that haven't been hurdled.
As of writing, the Perseverance rover is looking for evidence and analyzing the Jezero Crater however, scientists are aware that there are many fossil mimics that replicate biological signs and it has been increasingly difficult to tell them apart.
Organic-Looking Structures and Fossil Mimics
For generations scientists have been aware of dozens of natural processes that occur here and outside the planet that tend to create organic-looking structures. These fossil mimics are microscopic structures that have been fooling scientists since their discovery. In a study published in the Journal of the Geological Society, titled "False biosignatures on Mars: anticipating ambiguity" a pair of scientists outline problems with fossil mimics in the continuing search for real microscopic fossils on the Red Planet.
When it comes to false positives in the search for life on Mars, one of the most well-known examples is the Allan Hills 84001 meteorite that was discovered in Antarctica circa 1984, according to USRA. The meteorite, dated to be roughly 4 billion years old, is theorized as the time frame where Mars may have been briefly habitable.
Microscopic structures found in the Allan Hills meteorite had a distinct biological appearance. Measuring at only 20-100 nanometers, the theoretical size of a nanobacteria should be. On the other hand, they're smaller than all known life forms. Since then, researchers discarded the idea of the existence of nanobacteria. At the same time, the discovery of the biological structures in the meteorite attracted a lot of attention dragging the affair for years. Eventually, the scientific community moved on after realizing that morphology alone isn't enough to be used in the detection of primitive life.
ALH 84001 and the Pursuit of Life on Mars
Although the affairs of the ALH 84001 faded, it was a significant teaching moment for scientists. False starts such as the meteorite inspired new authors to take a more scrutinous look at abiotic origins of organic-appearing structures.
In a press release, Dr Julie Cosmidis, lead author of the study, explains that scientists have been fooled by past life-mimicking processes. Adding that on many occasions, objects that resembled fossil microbes were described in many ancient rocks on Earth and even meteorites originating from Mars. However, after deeper examinations they turned out to be non-biological origins. The recent study serves as a cautionary tale where researchers should look more closely on life-mimicking processes in the context of the Red planet to avoid numerous fallings and traps.
The authors point out that discoveries by the Perseverance rover on Mars may contain fossils that have ambiguous origins. If the rover does find something, the discovery is sure to spread rapidly. But researchers should show caution because of the presence of false positives, reports Inverse.
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