Best Evidence Yet for Past Life on Mars?

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By David L. Chandler, Sky & Telescope. 

Excerpt: The Perseverance has found compounds associated with life on Earth. But whether they indicate life on Mars awaits sample return. ...One rock,...is dotted with colored spots, ...The leopard spots, it turns out, appear to be reaction fronts — areas of contact between an expanding chemical reaction and surrounding rock. The material in the rings is composed of two different iron-rich minerals: vivianite (iron phosphate) and greigite (iron sulfide). Both of these minerals, on Earth, are usually associated with decaying plant matter or are products of microbial activity. ...The team cautions, however, that a non-biological formation process has not been ruled out. 


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