Nasa’s Perseverance rover has detected complex carbon molecules in Martian mudstones from the Bright Angel outcrop, located along Neretva Vallis, a dried-up river that carried water into Jezero crater billions of years ago. The discovery was made using the rover’s Sherloc instrument, which analysed the rocks with an ultraviolet laser.
The form of carbon identified, known as macromolecular carbon (MMC), can originate from living organisms but also from geological processes or meteorites. Dr Ashley Murphy of the Planetary Science Institute noted that MMC may come from fossilised organic matter or form through rock-water reactions, meaning its detection does not prove past life on Mars.
The Bright Angel mudstones previously caused a stir in 2024 when Perseverance found surface spots and nodules resembling features produced by fossilised microbes on Earth. Sean Duffy, former acting head of Nasa, described it as potentially the clearest sign of life found on Mars.
Tests on the Cheyava Falls mudstone revealed MMC on its surface, suggesting it was recently exposed or resistant to radiation and oxidation. This finding, reported in Science Advances, means Nasa rovers have now discovered organic-bearing mudstones more than 2,000 miles apart on Mars, indicating that organics may have been widespread across the planet billions of years ago.
Professor John Bridges of the University of Leicester called the work “more tantalising information” about the Bright Angel outcrop. However, the rover’s instruments cannot determine whether the carbon came from ancient microbes or non-biological processes. Scientists emphasise that definitive answers require returning samples to Earth, a mission now planned for the 2030s.
