Finding signs of life on Mars has long been an obsession for astrophysicists (and apparently, Elon Musk as well). And even though discovering an intelligent life form on Mars might sound too far-fetched, recent discoveries suggest that life may have existed millennia ago on the red planet at a microbial level. New research further supports the theory of ancient microbial life's existence on Mars, and backs it with the presence of chemical compounds called thiophenes in the soil sample from Mars collected by the Curiosity rover.
Thiophenes are essentially treated as an ancient biosignature on Mars, thanks to their organic structure. Washington State University astrobiologist Dirk Schulze-Makuch and Jacob Heinz with the Technische Universität in Berlin have published a paper in the Astrobiology, in which they've linked the presence of thiophenes in Mars' soil to the existence of microbial life on the planet. The latest research suggests that bacteria might have been responsible for the presence of thiophenes through a biological process, and whose remnants are now found in the soil of Mars.
However, theorising the presence of ancient bacteria on Mars through bacteria-catalysed biological processes is easy, but actually being able to establish a biochemical link with proof is a different thing entirely. And this is something even the minds behind the new research are aware of.
"We identified several biological pathways for thiophenes that seem more likely than chemical ones, but we still need proof. If you find thiophenes on Earth, then you would think they are biological, but on Mars, of course, the bar to prove that has to be quite a bit higher." Dirk Schulze-Makuch was quoted as saying in a Phys.org paper.
There are many chemical pathways that result in the production of thiophenes and even their breakdown by bacteria. On Earth, thiophenes are found in crude oil and mushrooms. Moreover, their ring-like molecular structure with carbon and sulphur atoms is considered a bio-essential element for life on Earth. But that doesn't mean they cannot be created without micro-organisms. In fact, a meteor impact can also lead to abiotic (something that does not involve any form of life) synthesis of thiophenes.
But scientists might have to wait a bit longer to conclusively decide where the thiophenes molecules discovered in martian soil were processed by ancient bacteria, or if it was just abiotic in nature. This is because the Curiosity Rover employs techniques that break larger molecules up into components, and these resulting fragments are what scientists get to analyse.
However, the Rosalind Franklin mission, set to take off in July this year, will utilise less catabolic methods, which means experts will be able to analyse larger molecules and get to know the true origins of the thiophenes molecules. And even though the presence of thiophenes possibly points toward a biological process on Mars, it might still not be enough. “I think the proof will really require that we actually send people there, and an astronaut looks through a microscope and sees a moving microbe,” added Schulze-Makuch.