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Comment by maaku | Hacker News Reader

And promptly sterilized. Unfortunately most plausible life forms require meters of soil/rock surrounding them to survive the harsh space environment (probably more in the vicinity of Jupiter).

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You obviously didn't read anything about the research. The analysis was focused on the likelihood of large chunks of rock being ejected during an impact, large enough to provide sufficient protection from the interplanetary radiation environment for geologically significant periods of time.

While I am not a biologist myself, I did work 2 years at the NASA Astrobiology Institute in a supporting role, where I learned all about the science surrounding this stuff. I don't know any astrobiologist who seriously believes that whatever microbes might exist in the comfort of Europa's inner ocean might survive free-floating in the harsh Jupiter radiation belts, where it takes hours or days (not millions of years) to sterilize all but the most extreme life forms.

"Jupiter radiation belts"

Found "Magnetosphere of Jupiter" on Wikipedia and it looks like the rest of my evening will be spent on this little tidbit. How could I never have heard about this.

Which is why it's far from a sure thing, only a possibility. However, if an object impacts Europa directly from a heliocentric orbit it won't spend much time in Jupiter's radiation belts. With enough luck maybe it would hit just the right patch of Europa to be captured in the ice and make its way down into the ocean without much exposure to radiation. Certainly that's a very unlikely event, as is simply getting a rock containing life from Earth to Europa in the first place. However, the Solar System is very, very old and in such stretches of time unlikely events can and do happen.

Ultimately the possibility cannot be conclusively ruled out, and given the implications it's worth considering.

The GP was about life from the ocean surviving the geyser into space, as "long string of frozen droplets that could contain organisms" in orbit around Jupiter.

We're finding extremophiles in all sorts of places we didn't expect. Radiation-resistant bacterial spores are hardly outside the realm of possibility - we've already found some.

Yes, but context. They're not likely to have evolved inside the relative oasis of Europa's oceans (or put differently, they're not likely to have retained any extremophile traits they might have once had).

Some water is clearly getting to the surface. If there's life, at least some of it is being exposed to decent levels of radiation.

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