Let’s just imagine, there we’re on a little spacecraft with the capability to melt to the ice, we push down, ‘mmm’, plowing through the ice. We hit the water, that may be an interesting sound right there at the interface between the water and the ice. When we look around, what we might see is a community of organisms that are growing on energy that’s coming through the ice, and oxidants, maybe even oxygen, produced by sunlight on the surface of the ice, being mixed through the ice, reacting with the water at that interface. Energy is being released. Organisms are consuming that energy. OK, that’s cool. We are going to go deeper down to the bottom of the ocean. There we see maybe hot hydrothermal vents, deep sea vents like we see on Earth or tidal energy, which is being caused by Jupiter’s gravitational pull, is pumping hot fluids through the crust. That’s a way we’re hoping to find.

 

On Earth we’ve found communities of life doing just fine, cut off from life above and huddling for warmth and sustenance around volcanic vents in the deep sea. This is what makes Europa so appealing. There should be warm salty water interacting directly with a hot rocky seafloor.

 

Life is like a little battery. It runs off a chemical reaction. If that rocky mantle is hot, then like black smokers on the ocean floors of the Earth, there could be the chemistry that powers life just pouring into that ocean from hot locations on that ocean floor. If Europa is an environment where we think there should be life, then it’s important to know, is there? Does life get going easily, given the right conditions? Or to that matter, if there is no life in Europa’s ocean and the conditions are favorable to life, why not? And how rare, then, is a life as we know it on Earth?