A 'sign' of ancient 'life' discovered on Mars? Speckled rocks offer a serious clue

If these features are the result of microbial activity that gives rise to minerals, as happens on Earth, then this is a sign of life on Mars. It's certainly premature to say so, but the recent research, published in the journal Nature, is promising. "We asked our scientific friends to analyze this and tell us if we're wrong or if these are signs of ancient life on Mars, and they said, 'Well, we don't see any other explanation,'" explained Sean Duffy, NASA's acting administrator.

"So this could very well be the clearest sign of life ever found on Mars," he added at a press conference. "It's a bit like seeing fossilized meal remains that may have been excreted by a microbe," said Nicky Fox, another NASA official. On Earth, this sedimentation is often the product of reactions of mud and organic matter, a possible "biosignature," and therefore a possible sign of life, according to the NASA study's lead author, Joel Hurowitz.

Perseverance's instruments have identified two minerals, vivianite and greigite. On Earth, the former is often found in sediments, peat bogs, and around decaying matter, and the latter can be produced by microbial life forms. "But there are also non-biological ways to produce these characteristics (Editor's note: the spots visible on the Martian rocks collected by Perseverance), and based on the data collected, we cannot rule out that this is the case," Joel Hurowitz warned.

But the results are "exciting," he said, explaining that researchers will need to analyze the samples in person to better understand whether microbial activity was responsible for the "fantastic features" and colors, including blue and green. That possibility seems unlikely, especially since the Trump administration planned to cancel missions to retrieve samples from Perseverance, one of the rovers currently circling Mars, searching for signs of life that existed there millions or billions of years ago.