To create her hypothesis, Noffke closely examined photographs taken by Curiosity and compared them to rocks on Earth that have definitely been formed by living organisms. She says the pictures returned by the rover look extremely similar to microbe-created rocks on our own planet. The specific photos Noffke studied were taken in Gale Crater, specifically in the Yellowknife Bay area which houses the Gillespie Lake outcrop. The bottom of the lake and bay, which once contained water, consists of sedimentary sandstone.
While there have been previous papers theorizing that certain rocks prove life on Mars due to the presence of fossils, those have often been debunked. Noffke’s work has been so thorough, though, that even NASA is impressed.
NASA spokesperson Chris McKay explained, “I’ve seen many papers that say ‘Look, here’s a pile of dirt on Mars, and here’s a pile of dirt on Earth. And because they look the same, the same mechanism must have made each pile on the two planets. That’s an easy argument to make, and it’s typically not very convincing. However, Noffke’s paper is the most carefully done analysis of the sort that I’ve seen, which is why it’s the first of its kind published in Astrobiology.”"
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