Monday, February 24, 2025

SPACE/COSMOS

 

Laser-powered device tested on Earth could help us detect microbial fossils on Mars



Scientists successfully identify microbe fossils in terrestrial rocks like those found on Mars, opening up the possibility of searching for fossils on the Red Planet


Frontiers




The first life on Earth formed four billion years ago, as microbes living in pools and seas: what if the same thing happened on Mars? If it did, how would we prove it? Scientists hoping to identify fossil evidence of ancient Martian microbial life have now found a way to test their hypothesis, proving they can detect the fossils of microbes in gypsum samples that are a close analogy to sulfate rocks on Mars.  

“Our findings provide a methodological framework for detecting biosignatures in Martian sulfate minerals, potentially guiding future Mars exploration missions,” said Youcef Sellam, PhD student at the Physics Institute, University of Bern, and first author of the article in Frontiers in Astronomy and Space Sciences. “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.” 

Water, water everywhere 

Billions of years ago, the water on Mars dried up. Gypsum and other sulfates formed when pools evaporated, leaving behind minerals that precipitated out of the water – and potentially fossilizing any organic life left behind. This means that if microbes such as bacteria lived there, traces of their presence could be preserved as fossils.  

“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.” 

But to identify these microbial fossils we first need to prove we can identify similar fossils in places where we know such microbes existed — such as Mediterranean gypsum formations that developed 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.” 

The scientists selected an instrument that could be used on a spaceflight: a miniature laser-powered mass spectrometer, which can analyze the chemical composition of a sample in detail as fine as a micrometer. They sampled gypsum from Sidi Boutbal quarry, Algeria, and analyzed it using the mass spectrometer and an optical microscope, guided by criteria which can help distinguish between potential microbial fossils and natural rock formations. These include morphology which is irregular, sinuous, and potentially hollow, as well as the presence of chemical elements necessary for life, carbonaceous material, and minerals like clay or dolomite which can be influenced by the presence of bacteria. 

Life on Mars? 

The scientists identified long, twisting fossil filaments within the Algerian gypsum, which have previously been interpreted as benthic algae or cyanobacteria, and are now thought to be sulfur-oxidizing bacteria like Beggiatoa. These were embedded in gypsum, and surrounded by dolomite, clay minerals, and pyrite. The presence of these minerals signals the presence of organic life, because prokaryotes — cells without a nucleus — supply elements which clay needs to form. They also facilitate dolomite formation in an acidic environment like Mars by increasing the alkalinity around them and concentrating ions in their cell envelopes. For dolomite to form within gypsum without the presence of organic life, high temperatures and pressures would be needed that would have dehydrated the gypsum, and which aren’t consistent with our knowledge of the Martian environment. 

If mass spectrometers identify the presence of clay and dolomite in Martian gypsum in addition to other biosignatures, this could be a key signal of fossilized life, which could be reinforced by analyzing other chemical minerals present and by looking for similar organically formed filaments.  

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

“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.” 


Gulf of Mars: Rover finds evidence of ‘vacation-style’ beaches on Mars



Penn State





UNIVERSITY PARK, Pa. — Mars may have once been home to sun-soaked, sandy beaches with gentle, lapping waves according to a new study published today (Feb. 24) in the Proceedings of the National Academy of Sciences (PNAS).

An international team of scientists, including Penn State researchers, used data from the Zhurong Mars rover to identify hidden layers of rock under the planet’s surface that strongly suggest the presence of an ancient northern ocean. The new research offers the clearest evidence yet that the planet once contained a significant body of water and a more habitable environment for life, according to Benjamin Cardenas, assistant professor of geology at Penn State and co-author on the study.

“We’re finding places on Mars that used to look like ancient beaches and ancient river deltas,” Cardenas said. “We found evidence for wind, waves, no shortage of sand — a proper, vacation-style beach.”

The Zhurong rover landed on Mars in 2021 in an area known as Utopia Planitia and sent back data on the geology of its surroundings in search of signs of ancient water or ice. Unlike other rovers, it came equipped with rover-penetrating radar, which allowed it to explore the planet’s subsurface, using both low and high-frequency radar to penetrate the Martian soil and identify buried rock formations.

By studying the underground sedimentary deposits, scientists are able to piece together a more complete picture of the red planet’s history, Cardenas explained. When the team reviewed radar data, it revealed a similar layered structure to beaches on Earth: formations called “foreshore deposits” that slope downwards towards oceans and form when sediments are carried by tides and waves into a large body of water.

“This stood out to us immediately because it suggests there were waves, which means there was a dynamic interface of air and water,” Cardenas said. “When we look back at where the earliest life on Earth developed, it was in the interaction between oceans and land, so this is painting a picture of ancient habitable environments, capable of harboring conditions friendly toward microbial life.”

When the team compared the Martian data with radar images of coastal deposits on Earth, they found striking similarities, Cardenas said. The dip angles observed on Mars fell right within the range of those seen in coastal sedimentary deposits on Earth.

The researchers also ruled out other possible origins for the dipping reflectors, such as ancient river flows, wind or ancient volcanic activity. They suggested that the consistent dipping shape of the formations as well as the thickness of the sediments point to a coastal origin.

“We’re seeing that the shoreline of this body of water evolved over time,” Cardenas said. “We tend to think about Mars as just a static snapshot of a planet, but it was evolving. Rivers were flowing, sediment was moving, and land was being built and eroded. This type of sedimentary geology can tell us what the landscape looked like, how they evolved, and, importantly, help us identify where we would want to look for past life.”

The discovery indicates that Mars was once a much wetter place than it is today, further supporting the hypothesis of a past ocean that covered a large portion of the northern pole of the planet, Cardenas explained. The study also provided new information on the evolution of the Martian environment, suggesting that a life-friendly warm and wet period spanned potentially tens of millions of years.

“The capabilities of the Zhurong rover have allowed us to understand the geologic history of the planet in an entirely new way,” said Michael Manga, professor of Earth and planetary science at the University of California, Berkeley, and a corresponding author on the paper. “Its ground-penetrating radar gives us a view of the subsurface of the planet, which allows us to do geology that we could have never done before. All these incredible advancements in technology have made it possible to do basic science that is revealing a trove of new information about Mars.”

The other corresponding authors on the paper are Hai Liu of Guangzhou University and Guangyou Fang of the Chinese Academy of Sciences. The other Penn State co-author is Derek Elsworth, the G. Albert Shoemaker Chair and professor of energy and mineral engineering and geosciences. The other authors are Jianhui Li, Xu Meng, Diwen Duan and Haijing Lu of Guangzhou University; Jinhai Zhang and Bin Zhou of the Chinese Academy of Sciences; and Fengshou Zhang of Tongji University in Shanghai, China.

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