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I have tried to get feedback on this before, and somehow did not.
If anyone cares to speculate with me either in the negitive or positive it will make me happy.
I have been considering what happens when a planet with more water than Earth, perhaps enough to cover most or all of the continents is outside of the habitible zone as normally defined. I think that there may be a process that may allow parts of the planet to be habitible.
The easiest to justify version would be around a Red Dwarf (M) star. The idea is favored by the planet being tidaly locked, but is not entirely dependant on it.
In the case of a Shallow ice planet (I would define that as too shallow to support a planet wide underground ocean, but with enough ice to allow a hole perhaps 5000 to 10,000 feet (or more) to be excavated by sublimination over time.
My logic on this is that Saturns Moon Titan can support a Nitrogen dominated atmosphere, so that is the aproximate limit of energy to support a non-collapse of the atmosphere.
Earth is too warm to support a planet wide deep glacier.
An Earth in the orbit of Mars could most likely support some open water ocean.
Perhaps the energy input to Ceres is what I am thinking of, but around a red dwarf star. A icy Earth with a layer of water ice perhaps 20,000 feet deep, or if you like 30,000 feet deep would behave as I think?
If it were an "Earth" around a Red Dwarf, and was tidal locked (Which is less likely the further you go out in orbit), it could be that the spectrum of the Red Dwarf would still actively evaporate the ice on the "Sunward" side, and escavate a very large pit.
Of course this disequilibrium would be answered by a more active glaciation trying to fill the pit, but a balance point would be achieved.
Without the use of exotic greenhouse gasses, an extra layer of atmosphere 10,000 feet deeper than the average surface of the glacier which would cover the dark side would provide warming for the sunward side at the lower elivations.
Supporting the atmosphere on the dark side is an issue. The further out you go, the harder it is to cycle enough heat to the dark side. However, it would be reasonable to speculate that it should be possible in some cases for the dark side to remain warmer than the condensing point of Nitrogen. Not CO2 however.
This presents a problem of carbon lockup, but it can be answered by the flows of glaciers into to sunward side pit. Of course the "Ice Pack" would have to have a lot of dry ice in it as well as H2O. But since that planet would not have as active a means to chemically lock up the CO2, a large content of CO2 is a real possiblity. So the carbon cycle for this planet would involve a glacial loop.
Also, for such a planet it is possible that tidal interactions with neighbor planets would cause subglacial volcanism, both bringing more CO2 into the surface, and also causing rivers to flow out from under the ice into the large pit on the sunward side. Unfortunately as in Iceland, many times this would be catastrophic floods, but it would still be able to fill bodies of water which would in time become salty.
A more secure location for life might be secured where the land at the bottom of the pit was elivated to a degree.
So such a world with an extra layer of trophosphere might allow for life support even outside of the normal habitible zone in the cold.
As for "Earths" around Yellow stars, it might be possible that a equatorial pit would erode, with two massive polar ice caps bounding it. Such a world would be more stable if it had a significant Moon, however in the absence of one, the pits would wander over the ages.
As for the notion that the ice of such a world would be permanently reflective, and so would cause a snowball Earth lock up, I am inclined to think that cosmic dust, and also dust storms originating in the deep pit would deposite a non-reflective coating to much of the ice cap. You might argue that Vapor from the pit would then deposite snow on top of that, but it cold be true that the mosisture in many cases would only escape from the pit at a low rate. Most of it would fall as rain or snow or hail back into the pit.
It would take millions of years to form such a pit.
Anyway, that is about it. Some worlds might fit into this other "Godilocks" zone. Many would fail for one reason or another, just like not every "Earth" in a normal habitible zone will have reached it's potential to harbor a livable habitat.
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Void-
I haven't posted in a while but this seemed quite interesting to me. I too have considered the habitability potential of worlds around red dwarf stars. Reasonably speaking, a tidally locked rocky (or watery) planet could be at a habitable temperature while being arbitrarily close to the star, because there will always be a cold side. In this case, the life forms would obtain energy almost by reverse photosynthesis: Energy would be obtained through radiating heat out into the external universe.
I don't know quite how deep one could make that hole, but I would expect that the warm side could easily have a significant depression relative to the cool side. Air would naturally collect there, although if there were any significant levels of heating then the surrounding ice would melt and eliminate the depression. I would expect an equilibrium to form at some point where the warm side is not significantly warmer than it would otherwise be.
-Josh
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It is why I don't believe in a "Snowball" Earth.
Should the Earth go into such a proposed lockup, even if very cold, as long as sublimination was in operation, a postive feedback would occur in certain locations where the temperatures were warmer than other locations. Even where liquid water is not possible.
The warm areas would loose lce and snow to the atmosphere as vapors, the even slightly colder areas would accumulate that as precipitation of frost and snow.
The topography would become uneaven. The Earth taken out to the Asteroid belt in my opinion would have continents covered in ice, and ocean basins where such holes would occur at the equator. The ultimate hole would be Marriana trench, is it 20,000 plus feet below the surace of the ocean? (I am not so interested in precise numbers, for hypothetical worlds, fuzzy thinking will work).
So, imagine sublimation digging those holes in a frozen ocean (The Earth suddenly in the Asteroid belt, with perhaps 25 % of the current solar lighting). Having an atmosphere, sublimation must occur. (Ceres only can hold ice it is presumed because of a layer of soil).
The positive feedback would cause any hole created by sublimation to go even deeper down to bedrock, because the deeper the hole, the more atmosphere above it and the warmer the greenhouse effect.
And by the way, thanks for the reply.
The negitive feedback to the above is that glaciers would try to close those holes.
Also consider the Antarctic dry valleys. Exactly what I have said above. And in those cases it also is observed that wind can sweep snow out of the depressions. Even more catabatic winds can descend into the valleys, and warm up from compression, and so become extreemly dry and so sublimate off the snow and frost that developes there.
It is in effect the "Desert" of a extreemly glaciated ice planet. By this method a habitate which is capable of supporting greater life is experienced. The dry valleys, do allow nematodes in the soil, and micobes in solar heated ice covered lakes. If the ice layer were twice as deep, and such a hole were dug, perhaps an environment supporting a desert type tundra would be possible, and go further, perhaps even tiaga with trees.
If a hole existed in our oceans (Frozen), then at the bottom of that hole would be a habitat with an additional 10,000, 20,000, 25,000 feet of atmosphere for greenhouse effect.
It brings up another curiousity. I think that during the ice age, when the oceans were maybe 200 feet lower, the humans living on the seashore would have had a better oxygen supply to breath, with a slighly more dense atmosphere at those locations. Such places close to the shores might have been warmer, and also had more shielding from UV and other radiation.
Last edited by Void (2013-04-06 23:27:47)
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I thought I could continue a bit more with the presumptions I have about the movement of water in such worlds, how it might be possible for liquid water in significant quantities to occur in such worlds in the warm places.
One is catastrophic floods, where volcanic activity would melt glaciers, and ice dams would burst. For worlds around red dwarfs, tidal heating due to relative proximity of orbiting worlds could keep this running long after radioactive decay has died down. Of course a catastrophic flood is not an ideal stable habitat. However a sea or ocean which recieves the floods may be more stable, but it's shoreline may fluctuate quite a bit. Some people think that tides were important to the developement of life. Worlds around red dwarfs might have tides not from moons but neighbor planets, and their may even be a rythm to the catastrophic floods, where peridic flexing might provide the stimulus for somewhat regular outbursts. Think Io but bigger and with Europa's ice on it, and with a central red star instead of Jupiter.
It is presumed by me that such a solar system as that would tend to accumulate ice on the side away from the central star (No mystery there), and that without watering a dry desert to bedrock would accumulate on the side towards the star.
Io may be too volcanic, but it is a reasonable example to illustrate what I am thinking.
So, catastropic (But somewhat regular) floods feeding seas, or even oceans.
But there is another way to water the deserts without rain.
There is evidence for this process on Earth although it is not developed to it's maximum potential benefit to life.
Antarctica has a high plateau, where a reservoir of cold air accumulates and the discharges, so it is an oscillation.
This may also occur to a degree in asia (And other places), but it is my understanding that heavy winds can actually blow snow from Siberia into the deserts to the south.
In Antarctica, the snow is dominantly blown into the ocean. It is dry, and behaves like dust or sand. However unlike dust and sand it can evaporate or even melt.
On the red dwarf worlds in some cases, I expect that these periodic wind storms (200 mph is possible in the dry valleys?), would blow snow off of the dark side and onto the deserts of the lighted side. Dunes of snow. Since this process will be periodic, then the weather on the lighted side could involve storms where the temperatures fall below freezing for at least part of the lighted side, and then the storm stops, and the lighted side warms up and might melt the snow. From this rivers and streams could occur, and of course depending on how much water soaked into the soil at a particular location, a watering of the ground.
One concern is if the water were to all get locked up on the dark side this process would stop. It would depend on the glacial process and the catastrophic floods to recycle it back to the lighted side, where it could evaporate, be carried to the dark side, and fall as very dry snow which would again be capable of being blown to the day side.
Obviously, the dark side may not be cold enough to condense Nitrogen, Argon, Oxygen? and other gasses, or indeed the atmosphere would collapse. Perhaps periodically.
As for CO2, the disposal of it on Earth is primarily by erosion of rock by water and deposition into aluvial fans?
On the worlds I am proposing, this could also occur, but it would also lock up into the glaciers, so the glaciers would be significantly composed of CO2. Glaciation and perhaps a wind blown process would recycle some of it to atmosphere.
The more that got permanently locked up, then the colder the day side, and the less the water flows. If volcanism is active, then that would push CO2 into the environment. It would freeze on the dark side and be released by catastrophic floods where carbonated water would issue out from the glacier bottoms, and by the glaciers pushing a mix of water ice and CO2 ice into the sunlight, and by wind blowing process.
I have read recently that the spectrum of light from a red dwarf is absorbed into ice much better than that of our sun, and so would be more energenic at evaporating and melting ice in a red dwarf system.
Last edited by Void (2013-04-07 11:14:58)
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