WASHINGTON – Scientists analysing samples collected by NASA’s Perseverance rover have identified complex organic carbon in ancient Martian rocks, providing further evidence that Mars once possessed chemical ingredients and environmental conditions that may have been suitable for life.
The findings, published in the journal Science Advances, focus on sedimentary rocks in Jezero Crater that formed beneath a long-vanished body of water between about 3.2bn and 3.8bn years ago.
Researchers examined organic carbon detected in two rocks, named Cheyava Falls and Walhalla Glades, which were sampled about 100 metres apart by the rover. The carbon is described as macromolecular carbon — a complex form that resembles carbon produced through both biological and non-biological processes on Earth, as well as carbon found in some meteorites.
The discovery marks the first time macromolecular carbon has been identified in mudstones within Jezero Crater, where Perseverance landed in 2021. NASA’s Curiosity rover had previously detected similar material in Gale Crater, roughly 3,700km away.
“These findings indicate that the habitability of Mars and the availability of organic materials may have been widespread across the planet billions of years ago,” said planetary scientist Kyle Uckert of NASA’s Jet Propulsion Laboratory, a co-leader of the study.
Organic carbon forms the chemical basis of molecules such as DNA, proteins and cells, making it an important target in the search for past life. However, scientists stressed that its presence does not constitute evidence of life because it can also be produced through geological and chemical processes involving rock and water.
Last year, NASA released images of the Cheyava Falls rock showing fine-grained rusty-red mudstone containing ring-shaped patterns and dark specks that on Earth can sometimes be associated with microbial activity. Researchers classified these features as a potential biosignature, meaning they could have a biological origin but require further study.
Using Perseverance’s SHERLOC instrument, the team conducted a more detailed examination of the carbon compounds but said the rover’s onboard instruments could not determine whether the material originated through biological processes.
“We need the return of these samples to Earth for more rigorous testing with higher sensitivity and higher resolution laboratory instruments,” Uckert said.
Scientists believe that early Mars had a thicker atmosphere and a warmer climate that allowed liquid water to exist on its surface. Jezero Crater is thought to have once contained a lake fed by ancient river channels, potentially creating habitats suitable for microbial life.
“The only place in the universe where we know life has emerged is Earth,” Uckert said. “If life is discovered on Mars, it could indicate that the emergence of life is not restricted to Earth, assuming the right conditions and ingredients are available, which would be a profound discovery.”
