NASA’s Curiosity rover continues making great progress in exploring the Martian surface. Along the way, the six-wheeled robotic Rover is searching for possible clues of past life on Mars. Now, it seems that the Rover has found conclusive evidence that life may have developed on the Martian surface in the distant past.

According to recent reports, NASA’s Curiosity rover has discovered organic compounds called thiophenes, consistent with the existence of past life on Mars, an astrobiologist at Washington State University has concluded.

Dirk Schulze-Makuch, together with Jacob Heinz, of the Technische Universität in Berlin, explored possible pathways for the origins of thiophenes on the red planet in a new article published in the journal Astrobiology.

Their work suggests that a biological process that probably involves bacteria may have played a role in the existence of the organic compound in Martian soil.

The researchers identified several biological pathways for thiophenes that seem more likely than chemical ones. However, the experts warn that further evidence is needed.

The researchers revealed that finding thiophenes on Mars, and Earth isn’t the same. If you find thiophenes on Earth, then you would think they are biological in nature. However, finding them on Mars is different. It takes much more to prove that Martian thiophenes are biological in nature.

Thiophene molecules have four carbon atoms and a sulfur atom arranged in a circle, and both carbon and sulfur are biossential elements. However, Schulze-Makuch and Heinz could not exclude the non-biological processes that lead to the existence of these compounds on Mars.

As one possible non-biological explanation, the scientists point towards Meteor Impacts, which can explain their existence in an abiotic way.

Thiophenes can also be created through thermochemical sulfate reduction, a process that involves a set of compounds that are heated to 120 degrees Celsius or more.

The most interesting explanation is the biological one. We really want to find alien life on Mars, and this explanation would catapult us in that direction.

That’s why the scientists explained that in the biological scenario, bacteria, which may have existed over three billion years ago when Mars was warmer and wetter, could have facilitated a sulfate reduction process that results in thiophenes.

Other pathways where bacteria break down thiophenes also exist. While Curiosity has provided many clues, it uses techniques that divide larger molecules into components, so scientists can only see the resulting fragments.

That’s why scientists want to gather more evidence form future missions on Mars, and the next Rover to set foot on the surface of Mars could provide much-needed answers.

The Rosalind Franklin Rover, which will launch in July 2020, could provide a significant number of clues. It will carry an instrument called the Organic Mars Molecule Analyzer, or MOMA, that uses a less destructive analysis method that will allow the collection of molecules.

Schulze-Makuch and Heinz recommend using the data collected by the Rosalind Franklin Rover to observe carbon and sulfur isotopes.

Isotopes are variations of chemical elements that have a different number of neutrons than the typical form, resulting in differences in mass.

Organisms alter the proportions of heavy and light isotopes in the compounds they produce that are substantially different from the proportions found in their building blocks. This is something Schulze-Makuch calls “a telltale sign of life.”

However, even if the next Rover gets this isotopic evidence, it may still not be enough to definitely prove that there is, or once was, life on Mars.

I guess the ultimate evidence to prove whether Mars was one inhabited by alien life would be gathered only when mankind sets foot on the red planet.