Is Laythe Actually Possible?

[brdavis]

But… Is a habitable moon around a gas giant possible?

I'd say yes, absolutely. A large Moon (planet-sized) in orbit around a very large gas giant, where the gas giant orbits in the habitable zone of the parent star, seems eminently "doable". Although the length of a solar day on said moon might be inconveniently long, still not a show-stopper by any means.

Is liquid water that far out from a goldilocks zone possible?

Hmm… on the surface? Open water? With an insolation that's 1/25th the Earths? It would seem very, very doubtful to me

Is a moon that's not super-radioactive around a gas giant possible?

Yes. All you need is shielding… although getting off-world is likely to be a rather short-lived endeavor.

I'd argue yes. Especially since a great majority of the gas giants we've found outside our system are much, much closer to their suns.

True, but note that there's a tremendous selection bias operating here. Distant gas giants (distant planets in general) are far less likely to be detected by both transit and radial velocity methods. You can guess the total numbers of planets in the galaxy, for example, but the precision depends on some assumptions about detection efficiency that are really not well understood as yet.

[Stargate525]

Hmm… on the surface? Open water? With an insolation that's 1/25th the Earths? It would seem very, very doubtful to me

But the original question wasn't 'is it likely,' it was 'is it possible.' I agree, the water would have to basically be sitting on a ball of tidally-heated magma, though if the water is polluted enough, you can buy yourself another 18 or 20 degrees of leeway in your freezing point.

Yes. All you need is shielding… although getting off-world is likely to be a rather short-lived endeavor.

LOL. I can imagine the poor inhabitants on their first Gemini missions, discovering that they're swimming in Chernobyl.

True, but note that there's a tremendous selection bias operating here. Distant gas giants (distant planets in general) are far less likely to be detected by both transit and radial velocity methods. You can guess the total numbers of planets in the galaxy, for example, but the precision depends on some assumptions about detection efficiency that are really not well understood as yet.

You've caught me. I do remember the mechanics of planet-finding from my own astronomy class. But it is undeniable that we've had to rethink the idea that gas giants only live out in the boonies of a solar system.

[Kasuha]

Edit: Wrong topic, sorry.

Edited December 10, 2013 by Kasuha

[Coupon]

And laythe would be hot enough for liquid water because of the friction heating, just like Io around jupiter is really hot

[Kasuha]

just like Io around jupiter is really hot

Hot you say?

... even volcanic Io has average surface temperature way below freezing (90-130K, i.e. -183 to -143°C)...

[Epthelyn]

And laythe would be hot enough for liquid water because of the friction heating, just like Io around jupiter is really hot

That's basically like saying the surface of the Earth is several thousand degrees above 0, when it clearly isn't. Io is volcanic because it of Jupiter's gravitational influence on the moon distorting it (or whatever the actual phenomenon is), as is the case for other similar moons in the solar system. Just because something has a volcano on it doesn't mean it has to be a nice warm place. It's far too far from the Sun to have a nice hot atmosphere.

[Guest]

I read where some of you are saying that radiation levels are high on moons around gas giants. Why is the radiation higher on these moons in comparison with our moon? I would think it should be lower seeing that they are farther from the sun, at least in our solar system. Just curious.

[brdavis]

But the original question wasn't 'is it likely,' it was 'is it possible.'

In that case, then, it's possible. Maybe due to a whole bunch of Squad miniliths acting as radiation-free fusion sources all over the bottom of the oceans. But short of nearly magic tech like that… yeah, highly highly HIGHLY unlikely

I read where some of you are saying that radiation levels are high on moons around gas giants. Why is the radiation higher on these moons in comparison with our moon?

Magnetic fields… they can save you, and they can kill you. Jupiter has a strong magnetic field, which means that any charged particles that end up in it, end up staying in it. The result is a belt of magnetically trapped high energy particles around objects with strong magnetic fields. Earth has them as well - they are just weaker. And still to be avoided on space missions, if at all possible.

Yeah… put that in. Radiation environments harsh enough to 'kill' or at least 'break' mission to some of KSP's planets. Ouch. Almost up there with an earlier suggestion that KSP model occasional unplanned engine failure.

Edited December 10, 2013 by brdavis

[Epthelyn]

I read where some of you are saying that radiation levels are high on moons around gas giants. Why is the radiation higher on these moons in comparison with our moon? I would think it should be lower seeing that they are farther from the sun, at least in our solar system. Just curious.

It's something to do with the giant ball of floating gas at the centre of the sub-system of solar system (i.e. the gas giant the moons are orbiting).

Earth/Kerbin is not a gas giant, therefore the moon doesn't have high radiations.

[Guest]

Ok, thanks. That makes sense about the magnetic fields causing problems. I guess a good example of this kind of activity would be the aurora borealis, although I've never heard about these being harmful here on Earth. But since Jupiter and Saturn are so much bigger, I can see where you could get yourself caught in a microwave, so to speak.

[Stargate525]

Ok, thanks. That makes sense about the magnetic fields causing problems. I guess a good example of this kind of activity would be the aurora borealis, although I've never heard about these being harmful here on Earth. But since Jupiter and Saturn are so much bigger, I can see where you could get yourself caught in a microwave, so to speak.

That's exactly what it is. The auroras are those particles interacting with the fields. There was an article on one of the newer exoplanets that suggests that it's so close to the sun, spinning so fast, and is so massive that the entire planet would be sporting those auroras constantly.

[James_Eh]

Yeah… put that in. Radiation environments harsh enough to 'kill' or at least 'break' mission to some of KSP's planets. Ouch. Almost up there with an earlier suggestion that KSP model occasional unplanned engine failure.

Heh. Or when you accidentally launch through a Trojan point the screen starts to get blurrier and blurrier, signifying dust pitting on the ports. (Thanks Larry!)

[brdavis]

I guess a good example of this kind of activity would be the aurora borealis, although I've never heard about these being harmful here on Earth.

Once a particle gets trapped in the Earth's field, it spirals around the magnetic field lines (OK, I hate that analogy, but it's sometimes useful). For low-energy (relatively) particles, they are "bounced back" or reflected from the polar regions (due to a higher field strength)… but if they are energetic enough, they spiral around those lines right down into the polar atmosphere, kicking the snot out of oxygen, nitrogen, etc., and making pretty lights.

You're right, that doesn't hurt you, even if you are "under" them… because a little bit of atmosphere is great shielding. Those particles are dumping energy into the upper atmosphere, instead of you, so this shows both the energy involved, and why an atmosphere (not a magnetic field in all cases) is enough to protect you. Upshot: a gas giant moon can have a habitable surface (due to an atmosphere), but might have a very very inhospitable radiation environment right outside the atmosphere (due to charged particles piled up in the gas giant's magnetic field). On Earth, we've got the "Van Allen radiation" belts… around Jupiter you have the "Van Allen you're already dead if you're here" belts.