Huge Ocean Confirmed Underneath Solar System's Largest Moon 117
sciencehabit writes The solar system's largest moon, Ganymede, in orbit around Jupiter, harbors an underground ocean containing more water than all the oceans on Earth, according to new observations by the Hubble Space Telescope. Ganymede now joins Jupiter's Europa and two moons of Saturn, Titan and Enceladus, as moons with subsurface oceans—and good places to look for life. Ceres, the largest object in the asteroid belt, may also have a subsurface ocean. The Hubble study suggests that the ocean can be no deeper than 330 kilometers below the surface.
Life (Score:5, Insightful)
And what have we here? Water, with trace elements, under pressure, with a magnetic field to protect against the worst of the solar radiation.
Re:Life (Score:5, Insightful)
Except it is not a solar radiation you need protecting against (Sun is very far), but Jupiter radiation. Unfortunately despite magnetosphere, Ganymede gets around 8 rem of radiation per day (http://en.wikipedia.org/wiki/Colonization_of_the_outer_Solar_System#Ganymede), which is bit too much for life as we know it. Fortunately, it is not going to be an issue 300km below the surface - but at that depth, you don't need magnetosphere anyway.
I think that biggest problem for life there would be availability of energy. 300km of crust is probably shielding external energy too well, so internal heat would be probably only viable source of that. Might be not enough to sustain life (or even more, to produce it randomly)
Re:Life (Score:5, Insightful)
Actually, it has been estimated there are so many deep-ocean species, that bioluminescence might be the most common method of communication on earth.
Re: (Score:3)
Some of them do. The ones that don't, however, rely (as far as we know) on 'marine snow' [wikipedia.org], which would not exist on Ganymede.
Re:Life (Score:5, Interesting)
Io - Molten sulphur on the surface, purple volcanoes all over it.
Europa - Deep water ocean, thin crust, very active plate tectonics.
Ganymede - Europa with a deep dish crust and cooler core.
Callisto - A rock.
So it would seem that gas giants may have their own "goldilocks zone" when they are orbiting in the colder regions of their host system. So the "average" solar system may have 3-4 "habitable zones" rather than just one.
Re: (Score:2)
Re: (Score:2)
However, whether those zones will be able to support life that will eventually develop into a space faring civilisation... I am not so sure.
A big barrier to that is the number of extinction events. The gravity from a gas giant pulls in a lot of passing comets and asteroids, that are quite likely to smack into the moons as they fall in. EEs would be ten to a hundred times more common for a gas giant moon than for a planet like Earth. The 1994 Jupiter impact would have likely wiped out any complex life if it hit a moon the size of Ganymede.
Re: (Score:2, Interesting)
Re: (Score:3, Informative)
Keep in mind that there is virtually no evidence for panspermia.
Re: (Score:2)
Life is obviously exceedingly adaptable; extremophiles in all kinds of crazy conditions have been discovered. But I don't think anyone suggests that life actually arose in such extreme conditions. You need somewhere more favorable for living organisms to come from, then produce extremophile descendants.
Not necessarily. You might need more time to produce viable life forms under less than ideal circumstances, but if you can support life at all, conditions could have created the life form in the first place. Of course, this is the big question - what parameters are really needed for life to form. Since we are at n=1, we need more data....
Re: (Score:2)
They mean that the depth of the liquid ocean is up to 330km deep; not that the crust is that thick above the liquid. As far as I know, thickness of the crust is at this point speculation. It has to have some substantial thickness; if it were very thin, we would expect to see lots of infrared escaping.
But it is not necessarily impenetrably thick. There could be things like atmospheric replenishment in Jupiter's general vicinity. Where the very cold atmospheric trail left behind removes heat from the frozen s
Re: (Score:2)
The four Galilean moons are interesting from an evolutionary POV. Io - Molten sulphur on the surface, purple volcanoes all over it. Europa - Deep water ocean, thin crust, very active plate tectonics. Ganymede - Europa with a deep dish crust and cooler core. Callisto - A rock.
Yes, I imagine the birds will have quite different types of beaks.
Re:Life (Score:4, Insightful)
On the other hand, heat built up by tidal forcing of Jupiter will also not be able to escape easily, through such a thick crust.
Heat "build-up" is not enough, you need a heat gradient with some sort of heat flow. Life and chemistry doesn't bypass thermodynamics. If the water and ground below it is very even, with the gradient in solid material above, there might not be enough of an energy source to allow life to form.
Re: (Score:2)
Actually, it has been estimated there are so many deep-ocean species, that bioluminescence might be the most common method of communication on earth.
I'm curious if you have a source for that estimate (because I actually would like to read more).
Re: (Score:1)
J. Frank Parnell
Ra-di-a-tion. Yes, indeed. You hear the most outrageous lies about it. Half-baked goggle-box do-gooders telling everybody it's bad for you. Pernicious nonsense! Everybody could stand a hundred chest X-rays a year! They oughta have 'em, too.
Re: (Score:3)
And all we need to do to take a sample is a launch a probe with a 300 km long drill bit. Easy peasy.
Re: (Score:1)
Just for reference:
The Kola Superdeep Borehole is roughly 12 km deep.
Re: (Score:2)
330km is the upper bound for depth, but the real question is, what's the lower bound? I want to see error bars!
Re: (Score:1)
330km from the other side.
Re: (Score:3)
Or if the surface is ice, with enough energy to melt through 300km of it. It still might need a 300km long antenna to tell us if it finds anything. I doubt a signal would go through 300km of solid ice very well.
Re: (Score:3)
it could leave a repeater at the top of the shaft before it starts boring in. It sends a low power signal to that, which then boosts it with a high-gain directional which stays pointed at Earth, or even a satellite with another repeater.
Yes, that's all very heavy, but so is 300km of cable
Re: (Score:2)
Under extremely low atmospheric pressure, it's likely the water would not stay water - it would sublimate to vapor. Nobody said it would be easy and wouldn't present challenges.
Re: (Score:2)
Would the borer have to be attached? It could trail a fiber optic cable.
But yeah, this is a bit "tricky" at best.
Re:Life (Score:4, Insightful)
And you know that those are the requirements for LAWKI how? Ignoring the fact that there could be entirely different requirements for other entirely types of life elsewhere, you have no clue how the earliest forms of life on Earth began.
If Titan's natural abiotic organic chemistry laboratory offers any clues, for example, the start of life could have come because of ionizing solar radiation, and in the absence of water, and only later developed into our present form. On Titan solar ionizing radiation builds complex organic compounds, some having been measured at over 10000 daltons, of carbon, hydrogen, and nitrogen, which raises the potential of catalytic cycles.
There have been countless proposed mechanisms for the earliest forms of autocatalysis that could have led up to the theoretical RNA world that could have led to our present world. And orders of magnitude more not yet conceived that could potentially have done it. It's silly to pretend that we have any clue exactly what the requirements are for the earliest "ancestor" to life on Earth. We don't know whether it developed in an ocean, on land, in a lake, in the soil, in rocks deep underground, in the troposphere, in the exosphere, in space... we really don't know. We don't know where it developed and we don't know what it was, and we don't know if it was the only way life could form (but I'd wager "no").
Re:Life (Score:5, Interesting)
I should add that we need to think better about how we want to think about early life, what's likely to lead to an evolutionary path.
On one hand, we have self replicators like the misfolded prions of BSE. Injected into a healthy human, a single misfolded prion can begin taking others in the person's body and misfolding them, leading to a catalytic cycle that spreads like a virus and eventually kills the person. One could conveive that if there were a wide range of "roughly prion-like" chemicals in some primordial soup, that their variations in folding could lead to evolutionary adaptation with time.
Is this reproduction some realistic sort of form of protolife? By far most people would say no. Prions are large, complex proteins; the concept of an early world containing large amounts of this exceedingly specific complex protein, or even proteins not exactly the same but still similar enough for reproduction, is exceedingly unlikely.
On the other hand, let's look at something like tin pest. Objects made of pure tin are stable at warmer temperatures, but at low temperatures they can develop something called "tin pest" where tiny spots break out, and then over the course of months expand and eat up the object, breaking it down into dust, like bacterial colonies spreading across a petri dish. This is a low-temperature stable allotrope of tin which catalyzes its own formation to reproduce itself.
Is this reproduction some realistic soft of form of protolife? By far, most people would say no. Contrary to prions, it's input is quite simple: plain, ordinary tin. It's easy to picture where this specific case or other natural cases like it could occur in some early world. But its problem is different: it's too specific. Tin pest seems unlikely to, say, mutate and start catalyzing the production of phospholipids or similar. It's just one self-catalytic reaction, with no real possibility for alterations.
The earliest forms of protolife surely lie somewhere on the spectrum in-between these two endpoints - not with such glaringly simple inputs as tin pest, such that your reaction is too simple to have any chance of it mutating without outright dying off, but not with inputs so complex as prions that you're unlikely to ever find significant quantities in nature. Surely the earliest forms were some sort of middle ground.
But what they were, specifically? This is totally and utterly unknown at this time.
Re: Life (Score:1)
Wow this is the most insightful comment on slashdot in eons
Re: (Score:2)
Tin pest fails the irritability life criterion, though: if you poke it, it does not respond. Do prions?
Re: (Score:1)
However, only protolife with variance can evolve. I'm not sure it's exhaustively impossible to see tin pest change: Consider some kind of unusual variant or alloy that is less susceptible to
Re: (Score:2)
Really what you describe is the RNA world hypothesis [wikipedia.org] (which you actually mention) - only you substitute some other polymer for RNA.
Breaking this down to first principles, you basically need conditions where ** something ** forms a semi stable polymer and those conditions are stable enough for random chance to allow autocatalysis. That something probably can't be just a metal but isn't necessarily carbon-hydrogen. So there are lots of potential environments for life to occur. How often this actually happe
Re: (Score:3)
But let us reword your position for a moment to point out the folly (currently at least) in its usefulness.
Here in my home country, if I desired a hamburger I happen to know from experience that most restaurants will have such a thing to sell to me. Ignoring jokes about McDonalds not having real food for just a moment, I know they are the most common place around to find a hamburger at.
Then you come along and (correctly, but uselessly) point out that the laws of physics do not rule out the possibility of f
Re: (Score:2)
Since we have no way to actually take a sample of the water on Ganymede, it's all just speculation anyway. And if we're just speculating, there's no point in restricting ourselves to Earth-like circumstances.
Re: (Score:2)
You missed short wave radiation. Earth has it, Ganymede does not. That could just any hope of finding life.
Finally! (Score:5, Funny)
Finally a reason to kick-start manned space exploration! Think of what can be learned! If there is life on these moons, then that means that it will also die. Dead plants means ocean floor sediment. That means there could be oil there! We now have a reason!
Re: (Score:2)
Re: (Score:2)
Maybe if we put down a giant monolith...
Re: (Score:2)
Actually... (Score:2)
...These kinds of finds are just fueling stations for future inter-planetary ships.
Re:So an ocean so deep that... (Score:5, Interesting)
Realistically, it's hard to picture any method that would work other than a nuclear reactor melting itself down through the surface. But then you've got the question of how to handle communications back to the top. That's a *lot* of ice to transmit through.
A 330km cable frozen into the ice that reforms above would be very heavy (tens of thousands of tonnes even if very lightweight), complex to feed, and probably have an unacceptable risk of breakage from shifting / settling ice.
I guess if you considered extremely low bandwidth acceptable you could use a neutrino pulse based transmission method straight from the probe.
Perhaps instead of 330km of cable you could drop behind hundreds of RTG-powered SLF radio repeaters (or thousands of ULF repeaters, or tens of thousands of VLF repeaters...). That'd still be of course incredibly heavy (not just for the power and radio equipment, but for the very sizeable antennae), but that'd likely be more workable than a single 330km cable.
I guess the last option that comes to mind would be to use exceedingly low frequency RF to try to go straight through the ice from the probe itself, less than 1Hz. But surely we're talking an antenna spread out over hundreds of square kilometers to be able to do that.
Re: (Score:3)
Hmm, it just occurred to me, yet one more possibility, and probably the most realistic: Fully autonomous probe. No through-the-ice communication. Contains ballast tanks. Heavier than ice when the ballast tanks are full, lighter than ice when they're empty. Mission: probe melts its way down, explores, flushes its ballast tanks with compressed air so that it's buoyant, then melts its way back to the surface. *Then* it can transmit everything that it discovered.
Re: (Score:2)
How about if we start by just landing on the damned moon and beaming back pictures? Maybe a Curiosity level probe, but leave the big drills until later. Who knows, maybe the Ganyamedians will come visiting [wikipedia.org] (yes, the reference is to Europa, but the idea is the same).
Re: (Score:3)
... SLF radio repeaters ...
Why try to brute force RF down at the DC level? Why not head to the other end of the spectrum and use lasers? If that water is relatively pure and there are few bubbles in the ice, I think lasers would win the size/weight to comm distance race.
BTW I love the idea of a modulated neutrino beam, except how much mass would it take to even modulate it enough to be detected?
Re: (Score:2)
Lasers wouldn't even come close to working, unfortuately. Ignoring that the fact that this isn't going to be pure, bubble-free, single crystal ice - celestial bodies just don't work like that - even if it was the laser light would still attenuate way too fast [google.is]. And it's even worse outside the visible spectrum.
Re: (Score:2)
I know the US Navy has performed experiments using lasers for submarine-to-surface comms [militaryaerospace.com] - no idea on how well that went.
How much does a 300km spool of fiber optic cable weigh again? :-)
I wonder if sound would provide a very low bandwidth channel? If you can get good coupling into the ice ot should transmit sound relatively well.
Re: (Score:1)
Re: (Score:2)
You got me thinking. Before I'd initially dismissed sound as you'd need strong earthquake-level power outputs to be detectable on the surface. But perhaps sound repeaters might be more realistic than extremely low frequency RF repeaters? Hmm.
Still, I think the best bet is probably just make it fully autonomous with ballast tanks and just have it surface. Ideally with enough fuel to do multiple up/down burrows, so that the first one can be a "safe" run - just down into the ocean, get as much science data (a
Re: (Score:2)
Would it help if you mounted the lasers on sharks ?
Re: (Score:2)
Re: (Score:1)
Re: (Score:2)
To see what our expertise in fossil fuel exploration has accomplished in this area, visit the Nevada Test Site: long straight drilled holes 8 and 12 feet in diameter. Nothing approaching 330m\km, though.
Kola Superdeep Borehole (Score:3)
Considering the deepest we've been able to bore a hole on earth with all the resources available (like air, gravity, equipment, people, etc...) was just over 12.2km deep they have a way to go...
http://en.wikipedia.org/wiki/K... [wikipedia.org]
I was trying to come up with an analogy of something impossibly far away, more so than boring a 330km hole, on a frozen moon, on another planet, and failed.
Re: (Score:2)
Admittedly though, the limits on depth of boreholes on Earth have been due to excessive heat at depth. That wouldn't be an issue drilling through ice.
Re: (Score:2)
True. However our collective experience equals 3.7% of that value...
Also I suspect that drilling through ice may have it's own challenges, particularly when highly tectonicly active.
Never mind just trying to transport 330km of drill there...
Re: (Score:2)
Earth First! We'll rape the other planets later...
Rocket Fuel (Score:1)
What has not been realised is, that water is actually rocket fuel, split it into oxygen and hydrogen. And Bob's your uncle.
Regards Peter.
Farmer in the sky (Score:1)
This story brings back memories of when I was a kid and read the book "Farmer in the sky" by Robert A. Heinlein. I really wanted to be there on Ganymede.
Maybe this increases the chances of us going there in the future provided we haven't bioengineered ourselves into extinction..
Re: (Score:2)
I propose the next probe or mission to Ganymede be called Torchship 1.
Re: (Score:2)
Yes it is, because Ganymede is fully differentiated geologically, with an iron core and a magnetic field.
Molten Ice (Score:2)
If this magma reaches the surface it could result in lava flows.
-
Awesome! (Score:1)
Now there's a chance we can have Ganymedian dolphin pilots for our star cruisers!!!
Re: (Score:1)
Re: (Score:1)
...or get your star cruiser stuck behind a floating piece of Star Cola plastic carrying rings
Looking for life? (Score:2)
Re: (Score:2)
Where are you planning to jump, if a Jupiter moon is a good "jumping off place" ?
Re: (Score:2)
Re: (Score:1)
Most of the world apart from the 5% who live in North America uses metric. Even the UK uses both Imperial and metric (although road signs are still in miles). In any case scientists and engineers all use units generally based on SI.
Slashdot has an international readership so metric is the right choice.
Re: (Score:2)
Slashdot has an international readership so metric is the right choice.
It shouldn't really matter, because by now we should all be used to the conversions, and capable of finding a conversion calculator for use when drunk
Slow Down (Score:1)
So, we're supposed to get excited because it has water? It has virtually no atmosphere. And from Wikipedia, the temperature never gets above 152K (that's -186F). Which of those two factors is going to allow for the evolution of any life form?
Re: (Score:2)
So, we're supposed to get excited because it has water? It has virtually no atmosphere. And from Wikipedia, the temperature never gets above 152K (that's -186F). Which of those two factors is going to allow for the evolution of any life form?
That's the surface temperature, liquid water oceans must be a lot hotter. Wikipedia estimates the core temperature as 1500–1700 K so there is certainly heat coming up.
Re: (Score:2)
That's surface temperature. This ocean is deep under the surface.
So the follow-up question would be: if it's deep under the surface, how will sunlight get there?
The answer is that sunlight isn't what's needed, it's the right amount of energy that's needed. The energy can come from a lot of other places. Tidal forces for example can heat the interior of the moon, radioactive decay can heat the core of a moon etc. so there may be quite a bit of subsurface energy. For example, if you look at the bottom of the
Oh Goodie (Score:2)
Re: (Score:2)
Now all we need to do is drill a hole
Simpler than that. Identify a fissure in the ice covering. Collect samples from the ice and look for biological material that might have been squeezed out at the time it opened.
... now that's something to "mine" ... (Score:2)
Re: (Score:2)
Hither and yon from there is nothing but a cold hard vacuum, as far as the eye cannot see. Whatever your plans are, it's not worth it.
And in other news (Score:2)
Huge oceans confirmed on the surface of Earth, larger than any others know in the solar system. One commentator stated, "While interesting it just isn't practical to explore or colonize these oceans. We would be better off spending trillions of USD to cross 628,300,000 km to explore and colonize a far off moon. In fact we would be better off spending that money instead developing hyper drive in vain hope we are not alone in this universe."
I could have told you that (Score:1)
If I stand on a boat in the middle of the Atlantic, I can look up in the direction of Ganymede and then I can look down at the ocean. Therefore, there is clearly a huge ocean underneath Ganymede.
Did Someone Say Moon? (Score:1)
The Moon: A Ridiculous Liberal Myth
It amazes me that so many allegedly "educated" people have fallen so quickly and so hard for a fraudulent fabrication of such laughable proportions. The very idea that a gigantic ball of rock happens to orbit our planet, showing itself in neat, four-week cycles -- with the same side facing us all the time -- is ludicrous. Furthermore, it is an insult to common sense and a damnable affront to intellectual honesty and integrity. That people actually believe it is evidence th
Utter bullshit (Score:1)
How many millions of dollars of taxpayer money went to 'prove' an ocean exists up to 330km beneath the moon of a planet 365 million miles away. What use is this to us... other than for a bunch of scientists to continue justifying their budget? Bah!
Re: (Score:2, Insightful)
When you slap labels on your "enemies" and then ascribe to them absurd positions you're doing yourself a disservice. You stop thinking rationally and dismiss any notion that doesn't already fit with your ideas.
Re: (Score:1)
Noticing what others say doesn't mean you actually paid attention, understood it, and are not replacing what they said with equivocation and strawmen.
By the way, it isn't just the "Greens" but also sailors lost at sea that talk about running out of water, which must be batshit crazy in your twisted view of things considering they are in a boat surrounded by water.
Re: (Score:1)
But sailors lost at sea would jury-rig a still, rather than publishing screeds opposing the desalination of seawater for human use. The Greens do, thereby proving batshit craziness.
Re: (Score:2)
You think Greens would actually support desalination? Look at these:
http://www.foodandwaterwatch.o... [foodandwaterwatch.org]
(Huntington Beach is a small coastal town in our country which is suffering a record drought).
http://www.citizen.org/documen... [citizen.org]
http://desalalternatives.org/ [desalalternatives.org]
http://www.dcbureau.org/201103... [dcbureau.org]
http://www.watereducation.org/... [watereducation.org]
These links are not about random ranters, but well-funded activist groups with the legal resources it takes to tie up vital projects for as long as it takes to starve them to death. It's ti
Re:That can't be right... (Score:5, Funny)
I'm pretty sure that's going to be the most stupid thing I read all day. ...
Ok. I HOPE, that's the stupidest, but I have a budget meeting in less than an hour, so I'm not really that confident.
Re: (Score:2)
Not a "Green" idea I've ever heard before, but even if was genuine, I really don't think that finding water 300km below the surface of a moon round Jupiter is going to be much of a solution except possibly in the very long term.