Moving a major step closer to proclaiming that life on Mars once existed, NASA researchers have discovered potential biosignatures in a sample collected last year by the Perseverance Mars rover, as announced in a new paper published in Nature. Those spots were of interest as potential signs that microbial life once used the carbon, sulfur, and phosphorus present as an energy source. Both of these minerals have links to life on Earth, with vivianite commonly found in association with decaying matter and greigite produced by some varieties of microbial life. Electron transfer between organic matter and the sediment left as a sign of past microbial life is the most likely explanation for the mineral traces, say the NASA researchers. Life on MarsWhile finding biosignatures is exciting in and of itself, where they were found leads to a significant rethinking of scientists’ previous assumptions about any possible life on Mars.