Unlocking Mars: How an Algerian Laser and Rock Quarry Could Uncover Microbe Fossils

Researchers are getting closer to finding fossilized microbes on Mars. A recent study examined microbial fossils found in gypsum on Earth. This gypsum formed when the Mediterranean Sea nearly dried up over 5 million years ago.

Long ago, Mars had rivers, lakes, and possibly an ocean. Today, all that water is gone, trapped in polar ice caps or lost to space. When water evaporates, it leaves behind minerals like sulfates. One important mineral is gypsum, known for its ability to preserve fossils. “It traps microorganisms before they decompose and keeps their biological structures intact,” said Youcef Sellam, a PhD student at the University of Bern.

Sellam collected gypsum samples from a quarry in Algeria, an area that was once underwater. Between 5.96 and 5.33 million years ago, tectonic activity caused the Mediterranean to nearly dry up. This created salt and sulfate deposits similar to those found on Mars, making the gypsum samples valuable for study.

To analyze these samples, Sellam used a small laser-powered mass spectrometer, which could potentially be sent to Mars on future missions. This device can detect biosignatures in sulfate minerals. “This technology could be useful for Mars rovers and landers,” he noted.

When the laser hits the sample, it vaporizes the material, creating a plasma of ionized atoms. A microscope then examines this plasma to identify the molecules inside. Sellam discovered tiny, twisted filaments of what are likely microbial fossils from sulfur-oxidizing bacteria. These fossils were found alongside clay minerals and other compounds.

This combination of minerals is significant. Dolomite, for instance, can dissolve in acidic conditions. Scientists believe Mars had very acidic water long ago. However, simple microbes could have helped create more alkaline conditions, perhaps aiding in the formation of dolomite and clays. If life existed on Mars, it could have influenced these geological processes.

While Sellam knew what to look for in his gypsum samples, identifying Martian fossils may be trickier. They could resemble natural rock formations, making it difficult to distinguish them from actual fossils. However, finding structures that look like fossils in gypsum rich with clay and dolomite would be a compelling sign of ancient life. “Our findings provide a way to look for signs of life in Martian sulfate minerals,” Sellam explained.

Future Mars missions should focus on finding dolomite and clay in gypsum samples. Despite the promise of this method, Sellam emphasizes the need for more research. “While our results support the idea that these filaments are biological, discerning true biosignatures from mineral formations is still a challenge,” he cautioned.

Sellam is excited to have led the first astrobiology study from Algeria and believes his findings mark a crucial step towards discovering life on Mars. The next rover to explore the planet, the European Space Agency’s Rosalind Franklin, is set to launch soon. It will come equipped with multiple mass spectrometers aimed at studying Mars’s minerals and searching for signs of ancient microbial life. Meanwhile, NASA’s Perseverance rover continues to collect samples to be brought back to Earth for further analysis.

Sellam’s research was published online on February 25 in Frontiers in Astronomy and Space Sciences.