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Originally Posted by EWright
Isn't one theory of how life began on earth, that it was seeded by debris from other parts of the galaxy slamming into the earth in the past? Why then wouldn't such theorists presume the same seeds were scattered throughout other parts of the solar system?
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That is what the theories say - the same elements were scattered all over the solar system, and are still here in pristine form inside comets. This is one of the prevalent ideas, and was supported by the initial findings in the Deep Impact mission this summer.
The observations at Saturn also appear to support such a theory.
However, the rings themselves are much too young to have been part of the early spreading of the chemicals which form the building blocks of life (as we call them), they are merely a few hundred million years old, compared to the 4,6 billion years that is the age of Saturn and the rest of the Solar System.
If the rings are a result of comets being crushed by Saturn, and then the debris being scattered around and "harvested" by the moons (several of Saturn's moons orbit inside the ring's gaps), then they were formed by the same kind of matter that spread those initial chemicals to Earth and as you mention, Europa.
However, water is not a sign of life. It is not a byproduct of it. It is, however, an expected prerequisite for it (we only know water-based life). All biological processes as we know them leave an imprint due to metabolism. This is observed on Earth. That is why methane on Mars and Titan have been interpreted as possible signs of earlier (or even current) life.
So yes, water on Europa, especially since it is expected to be a sub-surface ocean (the thickness of the crust is still a matter of debate since it is hard to measure - this will hopefully be done with later Jupiter probes), which means it may be a warm ocean if there are deep-sea vents, for example. That makes it possibly a very likely place for life to arise But we have yet no signs of it, and no tests for it.
