Stories from the Cosmos: Hunting Martians

For more than a century, humanity has dreamed of Martians. At the end of the 19th century, astronomer Percival Lowell drew a network of canals on Mars in his notebooks, convinced they were the work of a dying civilization trying to bring water from the poles to the equator.

Those sketches ignited the popular imagination and were the raw material for novels, comics and films that populated the red planet with green beings.

Over time, we confirmed that there were no cities or colossal engineering works on the Martian surface, but the obsession didn't disappear. Rather, it transformed into a much more sophisticated scientific quest, leading us to the recurring question : Can life exist on Mars, even if it's microscopic?

NASA recently announced results that put Mars back in the spotlight. Organic molecules have been identified in rock deposits in Sapphire Canyon that could be remnants of biological processes, or at least key ingredients for life . This isn't definitive proof of Martian life, but it is a tantalizing clue. This means that, like good cosmic detectives, scientists working in the field of astrobiology must tread carefully, keeping in mind that the same molecules can also originate through geological processes.

This new discovery adds to previous evidence, such as the methane detected by the Curiosity rover, which appears to vary with the Martian seasons ; hydrated salts that suggest the presence of liquid water in the subsurface; and microscopic structures reminiscent of fossils. Each new piece of evidence fuels the hypothesis that Mars may have been habitable in the past, when it was a warmer, wetter world .

If we ever confirm that there were, or still are, Martian bacteria, the impact will be monumental. First, because it would demonstrate that life is not exclusive to Earth , and therefore, if it arose twice in the same solar system, the probability that it is distributed throughout the galaxy would skyrocket. But we would also have a natural experiment to compare the evolution of life on Mars and learn whether it followed similar paths to those on Earth, or radically different ones. Perhaps we would discover that we share a common origin, in a process called panspermia , where meteorites ejected from one planet were able to seed the other with resistant microbes. Or perhaps we would confirm that life inevitably arises in the universe when the basic ingredients are present.

From another perspective, the hunt for Martians is also a mirror. It confronts us with the need to define what we mean by life and how we recognize it. This could involve the detection of organic molecules, the observation of cellular structures, or the identification of an active metabolism . This prepares us not only for Mars, but also for the study of exoplanets discovered around other stars, the number of which now exceeds 5,000.

At the same time, an ethical debate is emerging about whether we should protect Mars from terrestrial contamination before establishing human bases there, or about what it would mean to find a Martian biosphere . In any case, space exploration would cease to be a technological adventure and become a planetary responsibility.

The coming years will be crucial for the exploration of the Red Planet. The Mars Sample Return mission will bring samples back to Earth for analysis using cutting-edge technology, while new generations of instruments, including drills, cave-exploring robots, miniature laboratories, and high-precision satellites, will search for signs of life directly on Mars. Added to this are plans for manned exploration , which will eventually allow for real-time decision-making and the establishment of permanent scientific stations. Advances in artificial intelligence and bioinformatics, meanwhile, will optimize data analysis and facilitate the identification of potential biological signals amidst the geological noise.

The discovery of life on Mars may not happen tomorrow, but every breakthrough brings us a little closer to answering one of humanity's oldest questions: Are we alone in the universe?

Astronomical Observatory of the National University