Why Europa Is Awesome

[Th1sWasATriumph]

Actually, I don't think we know that yet. How do we know that the molecules, proteins, or simplest of life did not arise elsewhere and crash here from, say, a comet?

On the surface, that seems a nicely beguiling hypothesis - however, it doesn't actully help as we don't know the origins of these molecules. It's a workable theory, but not particularly supported by evidence, and wouldn't answer the question effectively - it's like attributing creation to God and then not wondering where God came from.