As the NASA team look at what’s in front of them, they can scarcely believe their eyes. There seem to be unusual signals coming from the distant moon of Europa – just one of dozens of mysterious satellites orbiting Jupiter. And although the data has traveled more than 390 million miles across the Solar System, the scientists are in no doubt about what it shows: a vast plume has burst forth from Europa’s surface. How big a deal is this? Well, pretty big! It may even have huge consequences for humanity.