Recently, NASA has discovered an FM singalong coming from Ganymede. While lots of people are hoping this is contact from aliens, NASA is telling the public its not that.
What seems to have happened is a natural function. The Juno spacecraft was moving between Jupiter and Ganymede, where magnetic field lines can occur.
In short, it was electrons doing their thing. This process is called Cyclotron Maser Instability. Juno will continue to do its mission, which is to study Jupiter to see how it changed overtime.
I mean, do we really want to see aliens? What if they want to harvest our brains?