Reply #6: One word: Europa [View All]

[Emperor_Norton_II]

The big discovery Galileo made was evidence of a permanent water ocean hiding under the surface of Europa. The same tidal forces that drive the volcanes on Io help warm the ocean enough to keep it liquid, and maybe down at the bottom create undersea thermal vents. The vents would provide enough energy to sustain life.

If Galileo was left to spin aimlessly around Jupiter unpowered, sooner or later it would hit one of the moons. NASA would rather it not hit Europa, because there's a chance that Galileo is carrying microorganisms form here that could survive the impact and contaminate an alien ecosystem.