Did Mars once host life? We finally know where to look

For years, Mars has captivated scientists in their quest to find signs of life beyond Earth. Though its dry, dusty terrain appears inhospitable today, the Red Planet once had water billions of years ago.

Pools and seas may have once covered the surface, much like early Earth. If life began there, just as it did here, could traces of ancient Martian microbes still exist?

A team of researchers believes they may have found a way to answer that question. By studying gypsum, a mineral known for preserving fossils, they have demonstrated that microbial life can leave behind biosignatures in sulfate minerals.

These findings could shape future Mars exploration, helping scientists determine whether life once thrived on the now-barren planet.

Detecting ancient life on Mars

Detecting evidence of ancient life on another planet is no simple task. Any method must be reliable, precise, and capable of working under Martian conditions.

Researchers from the University of Bern have taken a significant step forward by testing a laser-powered mass spectrometer on terrestrial gypsum samples. This instrument, designed for space missions, can identify biosignatures at a microscopic level.

Study first author Youcef Sellam is a PhD student in the Physics Institute at the University of Bern.

“Our findings provide a methodological framework for detecting biosignatures in Martian sulfate minerals, potentially guiding future Mars exploration missions,” said Sellam.

“Our laser ablation ionization mass spectrometer, a spaceflight-prototype instrument, can effectively detect biosignatures in sulfate minerals. This technology could be integrated into future Mars rovers or landers for in-situ analysis.”

The search for microbes

Mars once had abundant water, but it eventually dried up. Gypsum and other sulfates formed when these water bodies evaporated, potentially preserving organic life on Mars. If microbes existed, their fossils might still be present in these minerals.

“Gypsum has been widely detected on the Martian surface and is known for its exceptional fossilization potential,” explained Sellam. “It forms rapidly, trapping microorganisms before decomposition occurs, and preserves biological structures and chemical biosignatures.”

To verify this, scientists tested their detection methods on terrestrial gypsum where microbial fossils are known to exist. They studied Mediterranean gypsum formations created during the Messinian Salinity Crisis.

“The Messinian Salinity Crisis occurred when the Mediterranean Sea was cut off from the Atlantic Ocean,” said Sellam.

“This led to rapid evaporation, causing the sea to become hypersaline and depositing thick layers of evaporites, including gypsum. These deposits provide an excellent terrestrial analog for Martian sulfate deposits.”

Looking for life-essential elements

The scientists needed an instrument capable of functioning on a space mission. They chose a compact laser-powered mass spectrometer, capable of analyzing chemical compositions at a microscopic level.

They collected gypsum from Sidi Boutbal quarry in Algeria and examined it using the mass spectrometer and an optical microscope. Specific characteristics helped distinguish microbial fossils from natural rock formations.

These included irregular shapes, the presence of life-essential elements, carbon-based material, and minerals like clay or dolomite, which are influenced by bacterial activity.

Signs of life on Mars

The researchers discovered long, twisting fossil filaments in the Algerian gypsum. These structures were previously thought to be benthic algae or cyanobacteria but are now believed to be sulfur-oxidizing bacteria like Beggiatoa.

These bacteria were embedded in gypsum and surrounded by dolomite, clay minerals, and pyrite.

The presence of these minerals suggests biological activity. Prokaryotic cells influence clay formation by supplying necessary elements. They also help dolomite form in acidic conditions like Mars by raising alkalinity and concentrating ions in their surroundings.

Without organic life, dolomite would require extreme heat and pressure to form in gypsum, conditions unlikely to have existed on Mars.

If Martian gypsum contains clay, dolomite, and other biosignatures, this could indicate fossilized life. Scientists could confirm this by analyzing additional minerals and searching for similar organic structures.

Further research is needed

“While our findings strongly support the biogenicity of the fossil filament in gypsum, distinguishing true biosignatures from abiotic mineral formations remains a challenge,” said Sellam.

He noted that an additional independent detection method would improve the confidence in life detection.

“Additionally, Mars has unique environmental conditions, which could affect biosignature preservation over geological periods. Further studies are needed.”

Algeria’s role in planetary science

“This research is the first astrobiology study to involve Algeria and the first to use an Algerian terrestrial analog for Mars,” said Sellam.

“As an Algerian researcher, I am incredibly proud to have introduced my country to the field of planetary science.

“This work is also dedicated to the memory of my father, who was a great source of strength and encouragement. Losing him during this research was one of the most difficult moments of my life. I hope that he is proud of what I have achieved.”

The study is published in the journal Frontiers in Astronomy and Space Sciences.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–