NASA

Our reanalysis revisits Viking Carbon Assimilation–Pyrolytic Release experiment, which tested whether Martian soil incorporated carbon from supplied gases into organic material. Seven of nine usable runs produced significant positive signals, including one conducted in darkness. We examine why these results were dismissed, how perchlorate could have obscured part of the signal, and why proposed mineral explanations still fail to reproduce the full experimental pattern. Taken together with the Labeled Release results, the observations suggest that Martian soil both oxidized organic nutrients and fixed carbon from CO and/or CO₂ gases—a combination typical of a microbial community, whose experimental responses no known mineral chemistry has yet reproduced.