Comet Discovery Could Complicate the Search for Alien Life

The new observation, that the strange, duck-shaped comet that ESA’s Rosetta spacecraft has been orbiting for more than a year is blowing molecular oxygen, O2, into the space around it, not only force a reconsideration of the very early solar system, they also throw a bit of a curveball at scientists hoping to identify the signatures of life on other worlds. Of course, molecular oxygen is common on Earth, having first been pumped out in enormous quantities by photosynthetic blue-green algae about 2.5 billion years ago. Until now, though, astronomers have only spotted gaseous O2 in a handful of other places, including two distant molecular clouds. 

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