Some of the more interesting hypotheses about Europa include the possibility that the ocean may not only be able to support basic microbial life, there could be enough dissolved oxygen to support the evolution of complex, multi-cellular life forms. If you're thinking Europan jellyfish, you're not alone.
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In 2013, Hubble detected the presence of a plume of water vapor surrounding the moon, boosting hopes that geysers are blasting through Europa's thick crust, releasing some of the ocean's water to space. Europa became the second moon in the solar system, after Saturn's moon Enceladus, to be known to vent water through its icy crust. Not only does the presence geysers provide further powerful evidence of the existence of a liquid water ocean, venting it into space provides an opportunity for our robotic missions to directly sample the chemicals it contains. NASA's Cassini mission at Saturn has sampled Enceladus' briny water vapor and, after the 2013 Hubble find, hopes were high the same could be done for Europa.
However, the excitement was short-lived; Hubble couldn't repeat the observation, possibly indicating that the first vapor detection was in error, or a transient event like an asteroid impact.
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Could this "surprising activity" on Europa announcement on Monday be related to the detection of another plume of water vapor? If so, it will be a very exciting find, confirming the moon has an active sub-surface ocean that is released via geysers to space. And if this is the case, it will surely boost excitement for NASA's "Europa Clipper" concept as not only a mission that will study the moon up-close, but a sampling mission that could get a taste of Europa's sub-surface ocean to find out if it has the right ingredients for life.
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