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How to make an ice planet plausible


Mister Trent

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We've seen them many times in SF, planet Hoth from Empire Strikes Back being the one that comes to mind for most people. The Ice Planet: A planet that is more or less an oversized ball of ice and snow and yet, despite the apparent lack of a viable ecosystem, has a breathable atmosphere. The question is: how to make such a planet plausible in a campaign setting where at least some concessions to realism must be made?

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Re: How to make an ice planet plausible

 

I'd put it on the outer fringe of the Habitable Zone. Cold enough that giant glaciers cover most of the planet, but not so cold as to freeze everything out of the atmosphere. Sort of like a permanent Ice Age. There can still be an ecosystem, and there would probably even be open water in isolated areas (maybe a seasonal opening of the seas in the warmest climates. And of course, there would still be liquid water under the ice. Such a planet can be inhabited though like Antarctica, the colonists would have to stay in their habitat compounds continually, only venturing out into the icy wilderness with extreme preparations.

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Re: How to make an ice planet plausible

 

We've seen them many times in SF' date=' planet Hoth from [i']Empire Strikes Back[/i] being the one that comes to mind for most people. The Ice Planet: A planet that is more or less an oversized ball of ice and snow and yet, despite the apparent lack of a viable ecosystem, has a breathable atmosphere. The question is: how to make such a planet plausible in a campaign setting where at least some concessions to realism must be made?

 

Compromise. The only land is on the polar continents, so it's all frozen, but the oxygen is produced by plantlife in the equatorial ocean that bands the world.

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Re: How to make an ice planet plausible

 

Well, there is life that lives in subzero temperatures. Some forms of algae and bacteria, for instance. Anyway, I suspect "giant iceball" might be an exaggeration. There is, after all, native life in the form of the Wampa, and it obviously eats something. I'd imagine Hoth is just in an ice age... it probably has less cold months, maybe some plant life, and definitely oceans. Probably an icy planet's orbit is relatively slow.

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Re: How to make an ice planet plausible

 

Or that it's a ball of mainly Hydrogen, Oxygen and fairly inert gases that produce enough cloud cover to keep the surface frozen.. and most life occurs in the clouds, as tiny chlorophyl-producing aeroplankton.

 

Sure, there likely is a liquid center, and it may contain diverse life forms, but there's nothing to stop the planet from having a miles-thick crust of water ice, and still maintain a self-sustaining biosphere.

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Re: How to make an ice planet plausible

 

We've seen them many times in SF' date=' planet Hoth from Empire Strikes Back being the one that comes to mind for most people. The Ice Planet: A planet that is more or less an oversized ball of ice and snow and yet, despite the apparent lack of a viable ecosystem, has a breathable atmosphere. The question is: how to make such a planet plausible in a campaign setting where at least some concessions to realism must be made?[/quote']

A completely ice/snow covered planet cannot be combined with a breathable atmosphere on the surface. No oxygen-producing "plant' will grow if there's nothing but air and water to feed on; it will need minerals.

 

Internal heat sources keep the oceans liquid (at least below the surface ice)' date=' then the food chain goes from there?[/quote']

Entirely possible, but it won't give you a breathable atmosphere on the surface.

 

Compromise. The only land is on the polar continents' date=' so it's all frozen, but the oxygen is produced by plantlife in the equatorial ocean that bands the world.[/quote']

Entirely possible, but it doesn't follow the "classic" version of the "ice world," which has no open water. Though I'm with you: compromise is needed is plausibility is wanted.

 

Or possibly accept that there is plant life that can thrive in below- or near-freezing temperatures.

Possible, but how did it evolve? If all the water is frozen, how did some unfreeze long enough for plants to evolve, and then evolve "anti-freeze"? Anyway, I won't accept plants that don't need minerals. ;)

 

 

The short answer is: the "classic" version, where every square millimeter is covered with ice, yet there's a breathable atmosphere, is not plausible. A modified version, with extensive, open-water oceans full of oxygen-producing life is plausible. So I'd say, go that way. :)

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Re: How to make an ice planet plausible

 

Well, most of Earth's O2 is from cyanobacteria ("blue-green algae") so minerals dissolved in sea water are adequate. Still, your point is valid, because O2 production is due to photosynthesis, and you can't have photosynthesis on any real scale if the surface is largely ice: the sunlight won't make it through the ice layer unless it's so thin that the "ice world" label is a misnomer.

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Re: How to make an ice planet plausible

 

What's stopping plants from getting minerals? No one has stipulated that the ice cover on the ground is miles thick. And no one has said that the ice is a solid glacial sheet, as opposed to snow.

 

As far as how did the plants come to be in the first place, the planet could have been warmer at one time, maybe it's out farther from the sun than Earth is, but used to have a lot more CO2 in the atmosphere. Life forms, photosynthesis evolves, as the CO2 gets used up, the planet cools, plants adapt along with it. During the winter, the plants are dormant, with the exposed tops dying off. Snow piles up in winter storms. When summer comes, the snow starts melting (but never completely melts off), plants push through the top to collect sunlight, and grow runners to reproduce. Maybe, if it's warm enough, some seeds will sprout and get roots down into dirt and leaves (or needles) up into light before winter hits again.

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Re: How to make an ice planet plausible

 

ISTR seeing a program on the Science Channel (or was it the National Geographic Channel? :think:) In any case I googled "snowball earth" and "slushball earth" and got several relevant links.

 

Have a nut:

Wikipedia:

Online article by a Faculty member at Harvard University:

2005 article from

 

January 2000 article from

 

Another article in favor of

 

BBC News article:

 

Take your pick. There is a lot of wiggle-room between "Frozen wasteland" and "Giant Slushball".

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Re: How to make an ice planet plausible

 

Alternatively, the ice planet could merely have a non-biological source of O2. For instance, it could be orbiting in a zone within a celestial gas stream that contains oxygen which some sort of alternate stellar heating/cooling/magnetodynamic process separated out of.. well, something technical.

 

But, you know, in a sf sort of way.

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Re: How to make an ice planet plausible

 

The OP referred to sci-fi that do so stipulate.

 

Hmm...well I guess there are multiple ways to interpret "more or less an oversized ball of ice and snow", from planet-sized comet to planet nearly always covered with snow. But, "apparent lack of a viable ecosystem" does make things more difficult, and pretty well precludes macroscopic plants at all. That leaves cold-adapted algae scattered across the snowy surface as the only option.

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Re: How to make an ice planet plausible

 

You could have the dreaded example of a primitive ecosystem which evolves photosynthetic organisms, but with not enough components in the decomposer chain yet (or not numerically enough decomposer organisms) there is consequently such a draw-down of CO2 that the climate goes haywire.

 

There are many (confusing, in some cases) explanations of how a 'normal' ice age can get completely out of hand - for some ramblings on the subject (with academic references), visit http://www.palaeos.com/Proterozoic/Neoproterozoic/Cryogenian/Cryogenian.html and proceed to melt (or should that be freeze) your brain.

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Re: How to make an ice planet plausible

 

Do remember that Hoth's ecosystem existed in the same universe that had mynocks and giant moray eels living an asteroid that somehow maintained a high enough atmospheric pressure that Han could go out of the ship with just a breathing/filter mask...

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Re: How to make an ice planet plausible

 

Alternately, a mostly or entirely decomposer ecology, one that produces O2 (for whatever bizarre reason) in the process of decomposing whatever the planet's core material is. The core would be above freezing, despite the low surface temperature, to allow for liquid water, if liquid water is a pre-requisite for life.

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Re: How to make an ice planet plausible

 

Following up on Nolgy's atmosphere processing, it could be that a significantly high-tech civilization may have engineered entire worlds, under a number of scenarios.

 

It could be that a world was engineered and abandoned with the processing systems still intact and running. They could be monolithic processing machines, or huge surface greenhouses that grow wild.

 

The plant life thing depends on CO2 being present, anyway.

 

It could be that the world is a failed terraforming event and the atmospheric O2 levels are slowly falling through chemical conversion or what-have-you.

 

I think part of OP's question was looking for a naturalistic model for an ice world, and that's trickier. The "summer belt" of greenery on the equator would probably be best because it doesn't require as much land/water as you'd think, with less animal life breathing the O2, and probably less forest fires. It also allows you some terrain variation.

 

At the extreme end, a large icy satellite orbiting a gas giant might be affected by the larger world's awesome electromagnetic field in such a way that a natural hydrolysis occurs that breaks up some surface ice into hydrogen and oxygen, but even if that mechanism could work it would pose some pretty serious threats to visitors.

 

Would be a cool idea for a "puzzle" as to why an iceball has a breathable atmosphere.

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Re: How to make an ice planet plausible

 

Do remember that Hoth's ecosystem existed in the same universe that had mynocks and giant moray eels living an asteroid that somehow maintained a high enough atmospheric pressure that Han could go out of the ship with just a breathing/filter mask...

Also keep in mind that the OP isn't trying to justify Hoth, in the SW Universe... he used it as an example of an ice planet, but I don't think he's asking exclusively about that one single example. =)

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