NASA’s Perseverance rover has identified macromolecular carbon in two mudstones at the western edge of Jezero crater’s ancient river delta, marking the strongest organic detections yet recorded at the site. The measurements, made by the SHERLOC ultraviolet Raman spectrometer and published in Science Advances, revealed hundreds of organic signatures within rocks of the Bright Angel outcrop along Neretva Vallis, a dried river channel that fed the crater billions of years ago. The carbon appears in an amorphous form comparable to bituminous coal on Earth, a structure often linked to biological processing, though researchers stress that abiotic pathways cannot be ruled out.

Ashley Murphy of the Planetary Science Institute in Arizona, who led the analysis, notes that such macromolecular carbon “can originate from biological sources, such as fossilised organic matter found in microbial mats,” but also from water–rock reactions or meteoritic infall. The instrument is not designed to distinguish biotic from abiotic origins; its purpose is to map organic material and select samples for eventual return to Earth. The finding follows the rover’s 2024 observation of leopard-spot-like features on a nearby mudstone named Cheyava Falls, which some researchers viewed as the most compelling morphological hints of past microbial activity yet seen on Mars.

Viewed from the United States, the detection reinforces a pattern: the Curiosity rover previously found organic mudstones in Gale crater, more than 3,000 kilometres away. The geographic separation suggests that complex carbon chemistry was widespread on early Mars, at a time when both craters held persistent liquid water. Scientists at NASA’s Jet Propulsion Laboratory describe the Jezero organics as the most complex yet encountered on the Martian surface, and the first macromolecular carbon found outside Gale. The discovery does not confirm past life, but it adds a new layer of chemical evidence to the hypothesis that Jezero’s ancient lake–delta system once offered habitable conditions.

A separate study led by Slava Turyshev of the same laboratory, published in APS Open Science, quantifies the staggering physical requirements of terraforming. Raising atmospheric pressure to a level where liquid water could exist stably would demand adding roughly 10¹⁸ kg of gas—comparable to the mass of a small moon—while closing the 60°C average temperature gap would require orbital mirrors spanning some 70 million square kilometres. The analysis frames full planetary transformation as a project beyond current industrial capacity, likely centuries distant. The immediate next step for habitability science lies with sample return: NASA and China both target the 2030s to bring Martian rocks to terrestrial laboratories, where instruments can finally test whether the carbon macromolecules carry a biological signature.