The longest molecules ever found on Mars have been unearthed by NASA's Curiosity rover, and they could mean the planet is strewn with evidence for ancient life. Molecule chains containing up to twelve carbon atoms linked together were detected in a 3.7 billion-year-old rock sample collected from a dried-up Martian lakebed named Yellowknife Bay, according to a study published March 24 in the journal Proceedings of the National Academy of Sciences. These long carbon chains are thought to have originated from molecules called fatty acids, which, on Earth, are produced by biological activity. While fatty acids can form without biological...