Could Mars, once a warm and wet world, still harbour life? A team of scientists led by Andrea Butturini believes so. Their research suggests that the ancient Martian plain of Acidalia Planitia may be a potential haven for microbial life, particularly methanogens, lurking deep beneath the surface, according to the New Scientist.
By analyzing data from various Mars missions, the team has identified a subsurface zone, between 4.3 and 8.8 kilometres deep, where conditions could support microbial activity. This subsurface environment, shielded from harsh surface conditions, may retain remnants of ancient water and geothermal heat, crucial elements for life. While the idea of Martian microbes may seem far-fetched, this discovery sparks hope for the possibility of extraterrestrial life and opens new avenues for future exploration.
Taking data from the multitude of orbiters and rovers that have visited Mars, the researchers found that Acidalia Planitia - a 3000-kilometre-wide plain in the northern hemisphere of Mars - seems to have the right conditions for methanogens, methane-producing bacteria, an estimated 4.3 to 8.8 kilometres beneath the surface.
"[It is] a promising target area for future missions in the search for extant life in Mars' subsurface," the researchers write.
To uncover evidence of life on Mars, researchers would need to drill miles beneath its surface- an endeavour requiring advanced crewed missions and technologies that are still years away from feasibility.
This study, however, marks a significant step forward in the search for extraterrestrial life. By pinpointing a location beneath the Martian surface where microbial life might exist, it sets the stage for future investigations that could resolve the long-standing debate over the presence of methane in Mars' atmosphere.
The researchers suggest that methanogens-methane-producing bacteria could thrive under Mars' Acidalia Planitia region. These extremophiles are known to endure harsh environments on Earth, such as high temperatures, radiation, and ultra-salty conditions. They are anaerobic, requiring neither oxygen nor sunlight, and can survive on minimal nutrients. On Earth, methanogens are found in swamps, marshes, decaying organic matter, and even the guts of herbivores.
While the European Space Agency's Rosalind Franklin rover, set to launch in 2028, will include a drill capable of penetrating seven feet into the Martian surface, this depth is insufficient to reach the potentially habitable zone identified by the researchers. The surface of Mars is far too cold and low-pressure for even extremophiles to survive, but below the surface, conditions improve.
The radioactive decay of elements like thorium generates heat and chemical energy, and water remnants from ancient oceans are buried underground. Together, these factors could create a habitable environment for bacteria, likely at depths of up to five miles.
Biogeochemist Butturini of the University of Barcelona and his team used Mars orbiter data to locate regions with high thorium concentrations that could sustain microbial life. They matched this with subsurface ice maps created by missions like China's Zhurong rover. Their analysis identified the southern Acidalia Planitia as the most promising target, a mid-latitude region with signs of groundwater activity and clay and carbonate deposits.
At this depth, temperatures are more favourable, ranging between 32 to 50 Degrees F, potentially allowing for liquid water mixed with Martian soil-an essential ingredient for bacterial life.
Although the findings, currently available on the preprint server arXiv, have yet to undergo peer review, they are drawing attention for providing a specific site to focus the search for Martian life.
"The subsurface of the southern Acidalia Planitia is a putative target region for hosting cold-adapted Methanosarcinaceae-like and/or Methanomicrobiaceae-like methanogens," the study notes. It highlights the region's abundance of radiogenic heat-producing elements and the likelihood of subsurface water.
If proven correct, this research could not only confirm the existence of alien life on Mars but also provide indirect evidence that methane in Mars' atmosphere may have a biological origin.
