First of all, I think Europa likely has a water layer. And if it has life, with the high radioactivity of near-Jupiter space making even this possibly unlikely (and certainly hard to investigate), it's only going to be the equivalent of Bacteria.
Bacteria, Archaea, and similar life was all that was on Earth for most of its history. About 2 billion years ago, a number of rare events lead to a combining of them into Eukaryotes, the complex-structured cells that then evolved into all complex life forms. This is much less likely than the development of simple cell life like Bacteria.
Not necessarily, Jacke. Water and its ice are fantastic radiation shields. When you have a kilometer or so of solid-sheet ice, not much is going to get through, even from the radiation machine that is Jupiter. But even laying that aside, radiation isn't really a barrier to life. Complicating factor, sure, but life is...funny that way.
Radiotolerant organisms exist even on this planet. Deinococcus radiodurans was found growing near the blown-out core of Unit 4 in, yep, Chernobyl, and is even more durable. Thermococcus gammatolerans is the record-holder, able to tolerate doses even higher, finally crapping out around 30,000 Gy. But, granted, these are single-cell. Okay, how about tardigrades? Tardigrades can handle doses up to 5,000 Gy, about a thousand times what it would take to kill a human, and they're complex, multicellular organisms (albeit really tiny ones). The thing about life on Earth is that hard (ionizing) rads aren't really part of the picture for most of the planet.
Flip over to a radiosaturated environment. Any life evolving in that environment is going to be radiotolerant or even radiophilic; with hard rads bombarding the environment, selection pressure is going to favor first organisms that can tolerate radiation, and then those that thrive with it. Different environment means different rules, different pressures on evolution, and thus different outcomes. Could we find larger, more complex organisms in Europa's likely oceans? Sure. We even see examples of how they might tolerate such environments here on Earth. D radiodurans and T gammatolerans have multiple copies of their genetic data in their nuclei, using them to patch each other when they're damaged by radiation.
Much as Jeff Goldblum honestly annoys the ever-lovin' heck out of me, his character made a decent point in Jurassic Park. Life does find a way. It's an...elegant system, one not easily shut out. With enough pressure and enough generations for mutation to play out, evolution does crazy and amazing things. Fifty thousand mutants might not survive, but all it takes is one that does. Voila.
So what you're saying is, that if hostile life does exist on extremely radiated planets, we couldn't nuke them into submission?
I really really hate Jeff Goldblum. I don't even understand it meself. More like he's just taken on roles that make him say crap. (I've also really liked some characters he's done when I didn't realise it was him.)
Life doesn't always find a way. It's got to get started first. From what we know, Bacteria or something similar, yeah, that's likely. Like Eukaryotes, not necessarily. And when there's a lot of life, especially microbial life, they usually end up in a form that will do something. But life doesn't always find a way. When there's a lot of life, it won't all fail at once and can usually change.
So what you're saying is, that if hostile life does exist on extremely radiated planets, we couldn't nuke them into submission?
That's both awesome and concerning.
Nah, a nuke will still work. Ionizing radiation isn't what does the damage from a nukeblast; it's thermal and mechanical. An IR pulse sets everything flammable on fire, then a pressure wave (around 5 PSI or better) obliterates everything standing. They can be as resistant to rads as they like; the ability to mechanically withstand a nuclear blast would be incredibly difficult to evolve while remaining mobile. (Nuclear-resistant alien tortoise? Maybe, but you can outrun it on a Vespa.)
This should be renamed 'The science thread for smart-ish people'
ALSO, I have some/two pictures for you to argue over
Nice diagrams. There's another layer they didn't address, though. Assuming Enceladus or Europa have active planetary interiors, features like black smokers and other volcanic breakouts are likely. Chemosynthetic organisms use those resources in the same way that photosynthetics use light. The possibilities aren't endless, but far greater than we even understood a decade ago.
Comments
So what you're saying is, that if hostile life does exist on extremely radiated planets, we couldn't nuke them into submission?
That's both awesome and concerning.
ALSO, I have some/two pictures for you to argue over:
Life doesn't always find a way. It's got to get started first. From what we know, Bacteria or something similar, yeah, that's likely. Like Eukaryotes, not necessarily. And when there's a lot of life, especially microbial life, they usually end up in a form that will do something. But life doesn't always find a way. When there's a lot of life, it won't all fail at once and can usually change.
Nah, a nuke will still work. Ionizing radiation isn't what does the damage from a nukeblast; it's thermal and mechanical. An IR pulse sets everything flammable on fire, then a pressure wave (around 5 PSI or better) obliterates everything standing. They can be as resistant to rads as they like; the ability to mechanically withstand a nuclear blast would be incredibly difficult to evolve while remaining mobile. (Nuclear-resistant alien tortoise? Maybe, but you can outrun it on a Vespa.)
The Ripley Solution can remain in the inventory.
Nice diagrams.