The Hubble Space Telescope has obtained evidence of Jupiter’s moon Europa erupting plumes of water vapour, NASA reports. Hubble first caught a glimpse of the jets in December 2012, but now more plumes have been revealed using a different technique.
The discovery is exciting, as Europa, with its large subsurface ocean, is one of the best candidates for microbial life in the solar system – despite its surface temperature being a frigid -160°C. And plumes mean that samples of microbes could be collected during a flyby, without having to land on the surface.
Europa is Jupiter’s innermost large, icy moon (only slightly smaller than our own moon) and has about 100km of ice and liquid water surrounding its rocky interior.
Scientists started getting really interested in Europa following observations by NASA’s Galileo probe of Jupiter and its moons from orbit between 1995 and 2003. These showed that Europa’s surface ice is marked by multiple generations of parallel ridges and grooves, except where this pattern has been shattered by the surface breaking apart into randomly disposed slabs (known as “chaos regions”). This can be explained if Europa’s icy shell floats on a layer of liquid water. Each grooved ridge could mark a crack that opened and closed with the changing tide during Europa’s 3.5 day orbit of Jupiter – the ridges being formed from slush that was squeezed to the surface each time the crack closed. The chaos regions would represent slabs of the ice shell that broke apart as a region of the ocean became melted from below, powered by a release of tidal heat through the ocean floor – now frozen into a new configuration.