Author Topic: Radical Terraforming Methods  (Read 48467 times)

Offline indaco1

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Re: Radical Terraforming Methods
« Reply #80 on: 03/22/2012 11:37 am »
There's enough ice on Mars to cover the entire surface several meters deep.

Feeding people requires plants in light, far easier to do in a transparent structure.

Ice and water can both be highly transparent as long as bubbles and impurities are avoided.

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we have to find a design that could work everywere, not just on a small red planet

Why on (or off) Earth would you claim that ?? Do we only build structures on Earth that could work everywhere? Are houses in desert locations built the same as those in polar regions?

The thermal conductivity of ice over a temperature gradient of 10K/meter is 0.17Watts/m^2. getting rid of excess heat would be the problem - but not much of a problem in a cold atmosphere.

You need a good volume of air under the dome to minimize swings in CO2 concentrations throughout the day due to plant photosynthesis and respiration.


Requirements for structures that have to be permanently inhabited and requirements for the crops are completely different.

I agree that if we rely on solar energy we have to produce biomass in transparent structures. 

But I think they have to be light, small, expendable, not so shielded, mostly passive and allow more fluctuations in atmosphere composition.

I'm certain many vegetals, artropodes and even some vertebrates (maybe genetically modified) can thrive under radiation levels that are lethal for humans.

Furtermore, if a small module containing crop is lost it's not a great issue. The design has to be cheap, there's an optimal trade off between production costs and failure rate of modules for crop.

Habitable structures for humans, instead, have to be relatively big (humans need to interact) safe, with active life support to control air composition.

This is true both in space or on a planetary surface.

Consider that even if you live most of time in a closed environment sometimes you can go outside or in a less safe transparent structure using the proper equipement, accounting the dose of radiation you get and when sun flare forecasts tells you that it's safe.

You are right, it makes no sense to design a structure that works everywere.
I just was infatuated of the concept of sealed habitable box that works just providing power, an heat sink and a mean to produce gravity.

Mars offers much more than space, differnt requirements and different opportunities. On the other hand to put people in a gravity well make expensive them to travel.  I expect that most of colonies initially will be in cislunar space, where interactive communications are possible and it takes much less time and delta V to go than on Mars surface.   

By the way the straight pressure sustained structure in a crater concept could work on the moon also, providing you use glass or other that doesn't sublimate instead of ice. But I have no idea of how to build it... you can't pour liquid glass on a sheet of polyethylene.
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Offline RanulfC

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Re: Radical Terraforming Methods
« Reply #81 on: 03/22/2012 12:35 pm »
The often cited ideal of living under a huge glass dome is highly unlikely anywhere off Earth.
That's like, your opinion man.
Well, no actually it isn't JUST "my" opinion :) 

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Seriously, when I get to Mars, I want a really really big ice dome.  Made with clear-ice, and about 30 feet thick (600 feet or more in diameter would serve my needs well enough.  On the top of it, would be a clear sealant, and little robots like roomba vacuum cleaners (or pool cleaners) would run around dusting it off and adding sealent where/when needed.  Maybe they would be solar powered, maybe not.  On the inside edge of the dome, there would be clear insulation.  I will keep it a comfortable temperature, and have a lot of plants!  And a basketball court. 
Nice. Marshall Savage suggested a similar idea in using a dome that circulated water as radiation shielding. Just as an FYI though (in addition to the other cited issues) you'll need to build it up layer by layer and lay down layers of netting for strength and to prevent cracking. And at only 600-feet you might need additional internal supports to offset the overall mass. (Don't have my notes or my copy of TMP in front of me to check)

Note I'd suggest an inner double-plastic layer between the dome and inside air. Fill the layer with argon for insulation as it still allows maximum light through. (For that matter it might be wise to do the same for the outside for extra protection and to help keep the outer surface from getting too scratched up from dust built up)

Note also that 30-feet (which IIRC is about right BTW, though it might be a bit more) you get a significant shift in your light towards the red. You'd have to have supplemental lighting for your plants to grow properly.

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Construction technique would be similar to "monolithic dome homes".
Somewhat. You'll have to lay down a layer and then have the ice-roomba-bots "polish" it to be clear but it's doable.

Should also note that even with that much "shielding" even on Mars you're going to spend MOST of your time INSIDE for more shielding unless you want to hit your life-time limit within a couple of years. Just FYI :)

(Further from the Sun, but less magnetic field and less atmosphere means more get through to the surface. MUCH more on average.)

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As to the getting fancy, did you know that glass is almost entirely made from rock?  Make a silica glue-gun with your 3D printer there, and you've (eventually) got yourself a dome (if you want to do it the complicated way in comparison to ice). 
IIRC this was discussed on one of the Mars Society forums at one point. In comparison the dome (frame) itself was built of Martian iron while the glass infill was from locally produced silica. The problem here is your radiation protection is still basically zero inside one of these.

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Build a thick (strong) tunnel coming out of one end kind of like an igloo, and build a multi-stage fabric airlock inside it. 
While it's a nice idea you'd have constant air-and-volitiles leakage which leads to a bigger requirement for replacement. You'd want a couple of "air-tight" doors along the path just to cut down on your losses.
(Yes I read and enjoyed "A bucket of Air" also :) )

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If I can't build a dome I wouldn't plan to stay (just visit). 
You can build one, you just can't LIVE under one. Slight but important difference :)

People CAN live in enclosed spaces for long periods of time IF they spaces are designed correctly and care is taken to keep them from being confining, dark, and utilitarian. I cited the MMM article where they talk about bringing exterior views into the habitat in the form of "virtual" picture windows. It has to be done carefully and as noted probably won't be available on an individual basis but it's pretty easy to do.

nyar; you mention "Biosphere-II" as an "example" lesson for future space colonies. Unfortunatly you have "bought" into a false argument because one thing "Biosphere-II" proved rather pointedly is that it can't and won't be a "model" for any off-Earth settlement.

First of all, Biosphere II didn't really disprove anything.  There may be other (better) ways to do it than than the Biosphere II approach.  But I'll grant that Biosphere II suggested that completely closed loop may be impractably hard.  No problem.  Don't  plan to be "completely" closed loop.  Problem solved.   
[/quote]
Actually Biosphere II DID disprove quite a few things :) First and foremost was a lack of critical planning since quite a few design and construction details were not fully tested or vetted prior to being included in the planning. (The truss-system for one thing was KNOWN to cut out a lot of light coming in and was in fact choosen because the "calculated" light/heat gain was too high. In fact it turned out to be far too low)

I've already mentioned the concrete and oxygen issue.

Probably THE most important point as far as it goes is that though it was given as a "justification" for the experiment the overall design and construction of the Biosphere-II was NOT compatable with use off-Earth due to lack of radiation protection.

Reading through the rest of the responses I get the feeling that there is an assumption that having to live underneath the regolith is seen as being dark, dank and unpleasant. I don't suppose anyone actually looked at the article I cited?

People need "light" as well as plants and getting light (natural light) is not as tough as people seem to think. There are of course going to be varying "issues" depending on the location also but in general a design that works for the Moon will work for Mars and vice-versa. The further out you go the more difficult it will be gather, concentrate and direct light but it's still not impossible.

14-day Lunar nights are going to be an issue and require power reserves, while Martian dust storms while infrequent will require the same only deeper to cover the longer periods of reduced surface light. (As I recall one particular storm lasted almost a full Martian year)

But providing light while also providing a sense of spaciouness and openness is going to be a design challenge but nothing insurmountable. But it DOES take thinking about it NOW rather than waiting till one gets there because it IS going to take a readjustment of thinking.

indaco1 suggested a polymer dome over a natural crater, and that's actually a good starting point. I'll note that you can do this with a "berm" instead of a natural crater, or even a curtain wall but what-ever you use it's going to have to be opaque and thick. Instead of a polymer or ice "roof" though you would build a very low angle "conical" slab roof and cover it with  a couple of meters of regolith.

Now so far this sounds pretty much EXACTLY like a "dank-dark-cave" dwelling and it would be except you design it to bring in light and views of the outside. In my "Colony-In-A-Crater" concept plan I have the roof being supported by several columns (or a large central one depending on the size) each of which goes THROUGH the roof and is surmounted by a heliostat. From those the light is transmitted by mirrors or fiber optics to emmitters inside the roof. Further around the perimeter are optical "window" wells that take reflected light and bounce them through mirrors to provide large "picture-window" views of the outside.

Now the main "reason" for having a berm or crater wall this roof structure is mounted on is to so that the living quarters and most other "facilities" are then buried into the "walls" so that the majority of the space under the roof is open and used for growing plants and giving the residents a "park-like" area to avoid a shut-in, closed up environment. (Even though that is exactly what it is, the illusion of being otherwise is much easier to maintain)

This provides maximum protection for the residents while also avoiding the "termite-mound" or "living-in-a-mine" feelings.

As I noted it requires a change in the general mental process of thinking about "space colonization" but then it simply comes down to a design process. The hard part is going to be changing peoples 'Mind-Set' :)

Quote from: indaco1
To combat Malthus law we need to multiply Earth per 10^X, Mars surface is small.
"Malthus' Law" isn't really a "law" per-se as it only works under certain circumstances. Namely at the technology/wealth level and assumptions that were "true" in Malthus' time.

In fact as the wealth/technology level of the majority changes so does the ability to produce more food from the same land area using less energy and fewer "production" population. Further as a sociaty becomes "wealthyier/high-technology" the birth rate actually falls significantly. Since space travel/colonization takes certain tech/wealth level to be viable any civilization that undertakes the effort is going to be less and less concerned with population density concerns and probably able to gather and process more than sufficent resources to maintain themselves indenfinatly.

Malthus' assumptions were true and as far as he could "imagine" would hold true into the future. Less than 100 years after he wrote his paper on Population and Resource Scarcity (1798-1898) the formula had changed significantly. Even more so today as it was unknown in his time but well documented by the mid-80s and "proven" fact by the early 90s that higher wealth/tech populations stop growing and begin to decline over time. (Japan is currently the "leading" nation in population decline btw)

Most if not all the "scarcity" of resources in todays world are due to lack of transportation, or down-right obstructionism in many cases. (Famine in Africa for example)

This pretty much kills justifying space travel/colonization on the ground of population pressure or resource depleation. Which of course makes it harder to argue AGAINST space travel/colonization on those grounds too :)

Randy
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British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline A_M_Swallow

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Re: Radical Terraforming Methods
« Reply #82 on: 03/22/2012 01:18 pm »
{snip}
14-day Lunar nights are going to be an issue and require power reserves, while Martian dust storms while infrequent will require the same only deeper to cover the longer periods of reduced surface light. (As I recall one particular storm lasted almost a full Martian year)

But providing light while also providing a sense of spaciouness and openness is going to be a design challenge but nothing insurmountable. But it DOES take thinking about it NOW rather than waiting till one gets there because it IS going to take a readjustment of thinking.
{snip}

The plants are not only going to need light control but temperature control (including cooling), humidity control, water, air and radiation protection.  It will be easier to keep them underground.  Use solar panels and batteries to power electric lights.

Offline go4mars

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Re: Radical Terraforming Methods
« Reply #83 on: 03/22/2012 07:52 pm »
Out of interest, when did you first come across the idea of a Mars ice dome, I suggested it in May last year after googling unsuccessfully for the idea. (just wondering if I should apply for a patent on it  ;D )
I first started yammering about it on the web in 2006 or 2007 first on the old Mars Society forum.  Without much traction. 

Here's a more recent thread about it.

http://forum.nasaspaceflight.com/index.php?topic=26722.0

I'm sure if you search on this site, I've peppered in mention of a Mars Ice dome from time to time over the last few years.
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Offline Andrew_W

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Re: Radical Terraforming Methods
« Reply #84 on: 03/22/2012 07:58 pm »
There's enough ice on Mars to cover the entire surface several meters deep.

Feeding people requires plants in light, far easier to do in a transparent structure.

Ice and water can both be highly transparent as long as bubbles and impurities are avoided.

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we have to find a design that could work everywere, not just on a small red planet

Why on (or off) Earth would you claim that ?? Do we only build structures on Earth that could work everywhere? Are houses in desert locations built the same as those in polar regions?

The thermal conductivity of ice over a temperature gradient of 10K/meter is 0.17Watts/m^2. getting rid of excess heat would be the problem - but not much of a problem in a cold atmosphere.

You need a good volume of air under the dome to minimize swings in CO2 concentrations throughout the day due to plant photosynthesis and respiration.


Requirements for structures that have to be permanently inhabited and requirements for the crops are completely different.

Your actual house within the dome would be the disaster shelter.

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I agree that if we rely on solar energy we have to produce biomass in transparent structures. 

But I think they have to be light, small, expendable, not so shielded, mostly passive and allow more fluctuations in atmosphere composition.

I'm certain many vegetals, artropodes and even some vertebrates (maybe genetically modified) can thrive under radiation levels that are lethal for humans.

Furtermore, if a small module containing crop is lost it's not a great issue. The design has to be cheap, there's an optimal trade off between production costs and failure rate of modules for crop.

such transparent thin walled structures would require substantial insulation and/or heating to get the crops through each freezing night, not to mention what the freeze/thaw cycle would do to irrigation and other systems supporting many crops.

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Habitable structures for humans, instead, have to be relatively big (humans need to interact) safe, with active life support to control air composition.

This is true both in space or on a planetary surface.

Consider that even if you live most of time in a closed environment sometimes you can go outside or in a less safe transparent structure using the proper equipement, accounting the dose of radiation you get and when sun flare forecasts tells you that it's safe. 

Crops need tending and harvesting, people need to work in the shelters that house the farm, so such structures need to be safe for people as well.

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Mars offers much more than space, differnt requirements and different opportunities. On the other hand to put people in a gravity well make expensive them to travel.  I expect that most of colonies initially will be in cislunar space, where interactive communications are possible and it takes much less time and delta V to go than on Mars surface. 

Applies to all habitation systems on Mars so is not an argument against this habitat system vs other Mars habitat systems.

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By the way the straight pressure sustained structure in a crater concept could work on the moon also, providing you use glass or other that doesn't sublimate instead of ice. But I have no idea of how to build it... you can't pour liquid glass on a sheet of polyethylene.

For the Moon I'd go for a sintered regolith crater dome near enough to the pole to allow reflectors on high peaks to supply continuous sunlight through a dome light tube. on the Moon of course if you want a 0.5 bar atmosphere you need 30 tonnes regolith /m^2 or about a 15 meters thick dome.
« Last Edit: 03/22/2012 08:51 pm by Andrew_W »
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Offline Andrew_W

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Re: Radical Terraforming Methods
« Reply #85 on: 03/22/2012 08:30 pm »
Out of interest, when did you first come across the idea of a Mars ice dome, I suggested it in May last year after googling unsuccessfully for the idea. (just wondering if I should apply for a patent on it  ;D )
I first started yammering about it on the web in 2006 or 2007 first on the old Mars Society forum.  Without much traction. 

Here's a more recent thread about it.

http://forum.nasaspaceflight.com/index.php?topic=26722.0

I'm sure if you search on this site, I've peppered in mention of a Mars Ice dome from time to time over the last few years.

Oh well, I'll have to find something else to invent, after another Google I found a reference to the idea in 2004.

It would be interesting to build such a structure in some high latitude country or altitude location to trial it.
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Offline RocketmanUS

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Re: Radical Terraforming Methods
« Reply #86 on: 03/22/2012 09:33 pm »
Mars habitats
Multi story, people live at the lower levels and the top level for plants, roof transparent.
Multiple buildings together, share common side wall. Outer walls covered by Mars soil for radiation blocking and insulation.
Each level and between each building can have an air tight door to seal off any area that might leak air.

Offline go4mars

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Re: Radical Terraforming Methods
« Reply #87 on: 03/22/2012 11:43 pm »
It would be interesting to build such a structure in some high latitude country or altitude location to trial it.
Agreed.  It would need insulation on the top too so it wouldn't melt here on hot days/in the summer.  It would make a nice addition to the Flashline mars arctic research station! 

One of the challenges would be making the ice under "clear ice" conditions.  http://en.wikipedia.org/wiki/Clear_ice

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Offline go4mars

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Re: Radical Terraforming Methods
« Reply #88 on: 03/23/2012 12:04 am »
The thermal conductivity of ice over a temperature gradient of 10K/meter is 0.17Watts/m^2. getting rid of excess heat would be the problem - but not much of a problem in a cold atmosphere.
And a cold lithosphere (temperatures more stable down there through seasons and day/night cycle).

You need a good volume of air under the dome to minimize swings in CO2 concentrations throughout the day due to plant photosynthesis and respiration.
Agreed.  That's part of the reason for wanting a very large one.

I can simply build a 1km cube on the surface.   I'm aware it could look similar to a Borg ship....
Please do.  I'd like to see that.

We allow the outside of double glazed windows to be more than 0 degrees centigrade.  In Britain loft insulation in new houses has to be 270 mm (over 10 inches).  On Mars the roof will be a life critical system requiring higher standards.
It's a matter of heat flux.  Input vs. Output.  Efficiency only has to work within that.  Plus the thick ice provides a buffer from seasonal or diurnal extremes.   If needed to keep it from melting, alchohol or something could be circulated from tanks in the frozen lithosphere.  If the concern is heat loss, then either turn the heater up higher, or insulate more. 
to put people in a gravity well make expensive them to travel.  I expect that most of colonies initially will be in cislunar space, where interactive communications are possible and it takes much less time and delta V to go than on Mars surface.   
I disagree.  Once launchers are reuable (cue criticism), then Mars has a lot more to offer than cis-lunar for colonists.  It's a world with a useful atmosphere, essentially unlimited water, and .38 gravity. 

But I have no idea of how to build it... you can't pour liquid glass on a sheet of polyethylene.
Perhaps a castle of tight-fitting, sintered regolith blocks.  Build it like an igloo or arch, and seal it with a kiss.  A sloppy one.  The miniscule gaps between blocks will need some proper kind of slop (sealant).  Or a lasery one.  Melt the block edges together. 
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Offline LegendCJS

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Re: Radical Terraforming Methods
« Reply #89 on: 03/23/2012 12:25 am »

Out of interest, when did you first come across the idea of a Mars ice dome, I suggested it in May last year after googling unsuccessfully for the idea. (just wondering if I should apply for a patent on it  ;D )

Kim Stanley Robinson's wonderful (Red Green Blue) Mars trilogy features a cave dug into a Martian polar cap glacier.  It was apparently air tight and filled with breathable air, and very large.  Inside this cave a small town was set up with individual buildings.  I imagine its like life in an igloo when "outdoors" and pretty normal when indoors.
Remember: if we want this whole space thing to work out we have to optimize for cost!

Offline go4mars

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Re: Radical Terraforming Methods
« Reply #90 on: 03/23/2012 12:35 am »
you'll need to build it up layer by layer and lay down layers of netting for strength and to prevent cracking. And at only 600-feet you might need additional internal supports to offset the overall mass.
I don't think layers of netting are necessary.  The weight isn't glacial, and the gravity is a lot less.  But I haven't calculated it. 

Note I'd suggest an inner double-plastic layer between the dome and inside air. Fill the layer with argon for insulation as it still allows maximum light through. (For that matter it might be wise to do the same for the outside for extra protection and to help keep the outer surface from getting too scratched up from dust built up)
Argon triple-pane glass is pretty common in Calgary homes.  Newer ones anyways.  Sounds good to me! The atmosphere is 1.6% argon on Mars. 

Note also that 30-feet (which IIRC is about right BTW, though it might be a bit more) you get a significant shift in your light towards the red. You'd have to have supplemental lighting for your plants to grow properly.
30 feet is a general starting point based on matching the protection our atmosphere provides.  And as to magnetic field, there are times when Earth's polarity changes that we are thought to essentially have no magnetic field for thousands of years.  These do not coincide with biotic die-offs apparently.  So Mars's lack of magnetic field (reduced magnetic field actually since there are strong remanant patterns in areas) is not as big of a deal as it is made out to be.       Back to the thickness:  Thicknesses greater than that will depend partly on the pressure of the air within.  14 psi for example:  In Mars gravity, 14 pounds of ice with a footprint of 1 square inch would be ~940 inches tall = 78 feet thick (if I calculated that right) via 14 pounds / (68 pounds per square foot / 1728 inches) / .38.   

So looks like my 30 feet guess was off.  More like 100 feet thick (for safety margin). 
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Offline go4mars

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Re: Radical Terraforming Methods
« Reply #91 on: 03/23/2012 12:47 am »
Note also that 30-feet you get a significant shift in your light towards the red.
No you don't.  Net birefringence won't factor in.  Feel free to argue otherwises, but I'm pretty sure that is incorrect.

You'd have to have supplemental lighting for your plants to grow properly.
I doubt that.  There are lot's of shade dwelling plants that prefer indirect light on earth for one thing.  For another, you are essentially living in a giant lens (would need to make sure there isn't a potent focal point (unless that's your goal and it is an industrial dome).  But the plants that like light more can go closer to the focal area.  You could even put a one-way mirror on the inside perhaps.  Not that I am against artificial lighting as a back-up in case of planetary sand-storms etc.

Should also note that even with that much "shielding" even on Mars you're going to spend MOST of your time INSIDE for more shielding unless you want to hit your life-time limit within a couple of years. Just FYI :)
I'm not sure where you live, but in Calgary, for 8 months of the year, most people spend most of their time avoiding being outside.  A lot of people hardly ever go out! 

(Yes I read and enjoyed "A bucket of Air" also :) )
Never heard of it and google results look like nonsense.  Link?
« Last Edit: 03/23/2012 12:51 am by go4mars »
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Offline quixote

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Re: Radical Terraforming Methods
« Reply #92 on: 03/23/2012 09:14 am »
Quote from: go4mars
Never heard of it and google results look like nonsense.  Link?
http://en.wikipedia.org/wiki/A_Pail_of_Air

Offline RanulfC

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Re: Radical Terraforming Methods
« Reply #93 on: 03/23/2012 01:52 pm »
I don't think layers of netting are necessary.  The weight isn't glacial, and the gravity is a lot less.  But I haven't calculated it.
The netting has several purposes one of which is to provide superior strength for both outward pressure (atmosphere) and inward pressure (mass) to slow "creep" :)

Pretty much the same reasons the "form" is usuall melded with a Monolithic Dome structure :)

It also reduces the ability of cracks to propigate and helps keep the whole ice-form tied together.

And you'd probably use the netting to "tie" the entire dome into the foundation as well.

Note I'd suggest an inner double-plastic layer between the dome and inside air. Fill the layer with argon for insulation as it still allows maximum light through. (For that matter it might be wise to do the same for the outside for extra protection and to help keep the outer surface from getting too scratched up from dust built up)
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Argon triple-pane glass is pretty common in Calgary homes.  Newer ones anyways.  Sounds good to me! The atmosphere is 1.6% argon on Mars.
One of the reasons I suggested it :) 

Note also that 30-feet (which IIRC is about right BTW, though it might be a bit more) you get a significant shift in your light towards the red. You'd have to have supplemental lighting for your plants to grow properly.
Quote
30 feet is a general starting point based on matching the protection our atmosphere provides.  And as to magnetic field, there are times when Earth's polarity changes that we are thought to essentially have no magnetic field for thousands of years.  These do not coincide with biotic die-offs apparently.  So Mars's lack of magnetic field (reduced magnetic field actually since there are strong remanant patterns in areas) is not as big of a deal as it is made out to be.       Back to the thickness:  Thicknesses greater than that will depend partly on the pressure of the air within.  14 psi for example:  In Mars gravity, 14 pounds of ice with a footprint of 1 square inch would be ~940 inches tall = 78 feet thick (if I calculated that right) via 14 pounds / (68 pounds per square foot / 1728 inches) / .38.   

So looks like my 30 feet guess was off.  More like 100 feet thick (for safety margin). 
Actually makes it worse, but I was incorrect about the red shift.

Note also that 30-feet you get a significant shift in your light towards the red.
No you don't.  Net birefringence won't factor in.  Feel free to argue otherwises, but I'm pretty sure that is incorrect.
Actually it's a blue not a red shift and at about 30 feet you've already "lost" about 25% of your light:
http://en.wikipedia.org/wiki/Underwater
"With increasing depth underwater, sunlight is absorbed, and the amount of visible light diminishes. Because absorption is greater for long wavelengths (red end of the visible spectrum) than for short wavelengths (blue end of the visible spectrum), the colour spectrum is rapidly altered with increasing depth. White objects at the surface appear bluish underwater, and red objects appear dark, even black. Although light penetration will be less if water is turbid, in the very clear water of the open ocean less than 25% of the surface light reaches a depth of 10 m (33 feet). At 100 m (330 ft) the light present from the sun is normally about 0.5% of that at the surface."

You'd have to have supplemental lighting for your plants to grow properly.
I doubt that.  There are lot's of shade dwelling plants that prefer indirect light on earth for one thing.  For another, you are essentially living in a giant lens (would need to make sure there isn't a potent focal point (unless that's your goal and it is an industrial dome).  But the plants that like light more can go closer to the focal area.  You could even put a one-way mirror on the inside perhaps.  Not that I am against artificial lighting as a back-up in case of planetary sand-storms etc.
[/quote]
As above but I fully understand the "focal" point issue as this is what I thought of as soon as you said a "clear-ice-dome" :)
http://www.primitiveways.com/ice-fire.html

Note however that 100' is going to be even worse and "lens" effect or no it's not going to help all that much. Which is why I keep pointing out you can still have plenty of "natural" light without sacrificing protection, but there perists in being an "assumption" that living in a glass-dome is somehow "superior" and more natural :)

Should also note that even with that much "shielding" even on Mars you're going to spend MOST of your time INSIDE for more shielding unless you want to hit your life-time limit within a couple of years. Just FYI :)
I'm not sure where you live, but in Calgary, for 8 months of the year, most people spend most of their time avoiding being outside.  A lot of people hardly ever go out!
[/quote]
Currently in Utah and you tend to avoid spending a whole lot of time outside in both deep winter and high summer :)

You can still have pretty open spaces in buried habitats but as I noted there is a "mental" shift that needs to be made to most peoples perception of "colonization" off-Earth. Isaac Asimov actually tried to point this out over and over again. He had Agoraphobia and disliked going outside at all if he could aviod it. Whereas the majority of people around him would feel "crowded" and "trapped" inside a building he felt comfort and security. He noted once IIRC, that space enthusiasts, most Science Fiction writers, and the general public had a mis-conception of what travelling in space and living on other planets was going to be like. Most seemed to assume that it was going to be something along the lines of wide open space and huge glass domes. Instead the majority of time it would be like being inside a submarine, followed by being confined to an apartment building where you both lived and worked.

That attitude hasn't changed much that I've seen :)

(Yes I read and enjoyed "A bucket of Air" also :) )
Never heard of it and google results look like nonsense.  Link?
[/quote]
Oh? Wow... Ok but first where did YOU come up with that idea for an airlock?

Actually it's "A Pail of Air" by Fritz Lieber. Linked earc here:
http://www.baenebooks.com/chapters/0743498747/0743498747___6.htm

Short Version: A Dark Star comes rushing through the Solar System and snags Earth in it's gravity well. Yanks it right out of orbit and few people survive. Story is about a family group that manages to build a make-shift "Nest" and shelter out as the world goes cold. As far as they know they are the last humans on Earth. One of the "chores" that needs doing daily is someone has to go outside and scoop up a "pail of air" from the frozen oxygen piled up outside the shelter and one day the yound hero of the story sees "something" else. Something he's never seen before and it's coming closer...

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline strangequark

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Re: Radical Terraforming Methods
« Reply #94 on: 03/23/2012 06:47 pm »
I don't think layers of netting are necessary.  The weight isn't glacial, and the gravity is a lot less.  But I haven't calculated it.

Granted you can minimize the bulk stress, but you are still going to have other loads. There will be temperature swings (even on Mars), and subsequent expansion/contraction. As was mentioned, crack propagation in a monolithic ice dome over the long term is going to be a problem. It would be advisable to have a netting that is under high tension during deposition of the ice, and then release the tension afterward. This will put the ice into compression (same idea as prestressed concrete), and allow it to better resist all the incidental loads. You want to build an ice-matrix composite, more than anything.

Oh, and I did the math for a 600 foot diameter dome, with 30 feet ice thickness. Given an internal temp that is actively managed at 71 deg F, and an exterior temp of -55 deg F, you need 4 inches of polyethylene foam (or equivalent insulator) to keep the ice sufficiently cool. This is under standard assumptions for free convective heat transfer.

Offline go4mars

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Re: Radical Terraforming Methods
« Reply #95 on: 03/23/2012 07:05 pm »
Oh? Wow... Ok but first where did YOU come up with that idea for an airlock?
Daydreaming.  Given the nature of my posts, it shouldn't be too surprising that daydreaming gets me into trouble from time to time. 

It isn't like it's a complicated concept.  I'm sure dozens of sci-fi prone guys before me have independently thought of it.   

I've always been amazed by what people can dream up when thinking about a problem.  In every industry.  The Venus terraforming thread proves it!  The fact that we aren't still naked and eating whatever we can kill with our hands is prove of that.  Innovation is so cool! 
Elasmotherium; hurlyburly Doggerlandic Jentilak steeds insouciantly gallop in viridescent taiga, eluding deluginal Burckle's abyssal excavation.

Offline A_M_Swallow

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Re: Radical Terraforming Methods
« Reply #96 on: 03/23/2012 11:20 pm »
We allow the outside of double glazed windows to be more than 0 degrees centigrade.  In Britain loft insulation in new houses has to be 270 mm (over 10 inches).  On Mars the roof will be a life critical system requiring higher standards.
It's a matter of heat flux.  Input vs. Output.  Efficiency only has to work within that.  Plus the thick ice provides a buffer from seasonal or diurnal extremes.   If needed to keep it from melting, alchohol or something could be circulated from tanks in the frozen lithosphere.  If the concern is heat loss, then either turn the heater up higher, or insulate more.

The concern is that the heat from the people, machines and buildings will melt the ice.

Offline strangequark

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Re: Radical Terraforming Methods
« Reply #97 on: 03/23/2012 11:52 pm »
The concern is that the heat from the people, machines and buildings will melt the ice.

A 200m diameter dome would enclose about 8 acres. Given the assumptions in my previous post (where the ice doesn't melt), you would radiate 430 kWth. The human body, or similarly sized mammals (I would want my dog), radiates at 100W. In the energy profligate US, we use 10 kW per person of total power (electrical, gasoline, heating oil, etc). That encompasses all manner of industrial action that wouldn't be done inside on Mars. But let's stick with that ridiculously conservative number. That means that our 8 acres could support maybe 8 households (including machines, buildings, and farm animals). That is assuming you aren't using the surrounding regolith as a heat sink for an actively managed system, which you definitely would. 1 household per acre doesn't sound that bad to me. Sure it's not New York City density, but this is a village where you're growing your own food. In fact it might be a little dense.

EDIT: And I should mention that this is assuming a pretty flat dome. If we're talking a full hemisphere, then you radiate twice that.
« Last Edit: 03/24/2012 12:00 am by strangequark »

Offline A_M_Swallow

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Re: Radical Terraforming Methods
« Reply #98 on: 03/24/2012 01:14 am »
The concern is that the heat from the people, machines and buildings will melt the ice.

A 200m diameter dome would enclose about 8 acres. Given the assumptions in my previous post (where the ice doesn't melt), you would radiate 430 kWth.{snip}

Thank you for calculating the minimum size of heating required.  To maintain the air at 71 degrees Fahrenheit addition heating will be needed.  The heating also has to allow for convection cooling of the dome and melting of the ice.

The same problem continues, we have a heat source underneath the ice.

On the Earth Eskimos may build igloos out of ice but use materials with higher melting points for permanent dwellings.

Offline strangequark

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Re: Radical Terraforming Methods
« Reply #99 on: 03/24/2012 05:58 am »

Thank you for calculating the minimum size of heating required.  To maintain the air at 71 degrees Fahrenheit addition heating will be needed.  The heating also has to allow for convection cooling of the dome and melting of the ice.

The same problem continues, we have a heat source underneath the ice.

On the Earth Eskimos may build igloos out of ice but use materials with higher melting points for permanent dwellings.

It doesn't matter if you have a heat source underneath the ice. The ice will conduct the heat through, and reject it to the cold environment. I proved that with a little polymer insulation, the ice will not melt if the internal air temperature is around room temp.

Keeping the internal temperature at that set point is the kind of simplistic task accomplished by a thermostat and a heat pump. This part IS NOT rocket science.

You're acting like this requires some huge, delicate balancing act to keep from catastrophic failure, when it is really a very simple problem. Although I think there are some answers to be had about the best way to lay down, and reinforce the ice dome, I say three cheers for it.
« Last Edit: 03/24/2012 06:08 am by strangequark »

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