I always get giddy when talking about Europa, as many astronomers do.  It’s one of the most fascinating places in our solar system when it comes to the search for life.  It has lots of water, likely contained in a subsurface ocean.  It’s heated though a gravitational tug of war with Jupiter and the other Galilean moons.  And, as of recently, it has a chemical production system that matches Earth’s. I wonder what goes on beneath the thick ice of Europa.  Is there an ecosystem filled with alien life down there?  Life in Earth’s oceans feels very alien, but creatures from...