Finding evidence for life on Mars has been a decades-long ambition for NASA, which has spent billions of dollars to send machines wheeling over, poking and probing the Red Planet. But once the signs of life are found, how are those findings verified?
In early January, NASA's Curiosity Mars rover came across what some researchers thought might be trace fossils on Mars. Researchers first spotted the eye-catching, tiny, stick-like features in black-and white imagery, but they were compelling and unusual enough for the rover science team to roll the robot back to further interrogate them.
A strictly mineral origin was deemed to be the most plausible. Still, for some, the features suggested bioturbation—a process through which organisms living in sediments can disturb the very structure of those sediments. The oddities looked similar to Ordovician trace fossils here on Earth, which stem from an era more than 440 million years ago. [12 Possible Reasons We Haven't Found Aliens]
Regarding trace fossils on Mars, "We don't rule it out," Ashwin Vasavada of NASA's Jet Propulsion Laboratory in Pasadena, California, and project scientist for the Curiosity Mars rover, told Space.com. "But we certainly won't jump to that as our first interpretation."
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