Europa Plumes

Europa's water plumes

Today NASA announced the discovery of plumes of water vapor spouting from Europa, one of Jupiter's moons. It is presumed that the water originates from an enormous ocean beneath Europa's icy surface. This ocean has inspired much speculation about the likelihood that it could harbor some sort of life. The vapor shoots 125 miles up into space. Today's news means that we could sail a space probe through the plumes of vapor to analyze their chemical composition, looking for signature traces of life, or life-like processes, that might be taking place in the sub-surface sea. This will be much easier and cheaper than drilling through the ice and deploying a robot submarine. (Though ultimately, to get the full picture down there, I suspect we are still going to want to do the submarine some day.)

The evidence for these jets of H2O was gathered by the Hubble Space Telescope. The image that accompanied the press release (shown here) is a composite of an older shot of Europa, superimposed with the more recent Hubble photo of water plumes emerging from the lower left. So yes, it's Photoshopped. But it gets the general idea across.

We have seen a similar phenomenon before, geysers of water erupting on Saturn's moon, Enceladus. A subsurface ocean is suspected there, as well - though likely much smaller than Europa's. How can so much liquid water persist on these frozen little worlds? It is caused by tidal flexing, periodic distortions of the shape of these moons, due to the extreme gravitational tugs of huge Jupiter and Saturn. Similar to a potter warming up and softening a ball of clay by kneading it for a while before shaping it, when these moons flex, their atoms and molecules rub together with a great deal of friction, generating heat, which keeps the water melted.

NASA does have plans to send two missions to Europa, launching in in 2022 and 2025. So in another decade or so, we shall find out much more about these plumes and the hidden ocean from whence they come.