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.Quotewe 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.
we have to find a design that could work everywere, not just on a small red planet
Quote from: RanulfC on 03/21/2012 08:06 pmThe often cited ideal of living under a huge glass dome is highly unlikely anywhere off Earth. That's like, your opinion man.
The often cited ideal of living under a huge glass dome is highly unlikely anywhere off Earth.
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.
Construction technique would be similar to "monolithic dome homes".
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).
Build a thick (strong) tunnel coming out of one end kind of like an igloo, and build a multi-stage fabric airlock inside it.
If I can't build a dome I wouldn't plan to stay (just visit).
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.
To combat Malthus law we need to multiply Earth per 10^X, Mars surface is small.
{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}
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 )
Quote from: Andrew_W on 03/22/2012 08:06 amThere'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.Quotewe 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.
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.
Quote from: Andrew_W on 03/22/2012 06:11 amOut 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 ) 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=26722.0I'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.
It would be interesting to build such a structure in some high latitude country or altitude location to trial it.
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.
I can simply build a 1km cube on the surface. I'm aware it could look similar to a Borg ship....
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.
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.
But I have no idea of how to build it... you can't pour liquid glass on a sheet of polyethylene.
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.
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.
Note also that 30-feet you get a significant shift in your light towards the red.
You'd have to have supplemental lighting for your plants to grow properly.
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
(Yes I read and enjoyed "A bucket of Air" also )
Never heard of it and google results look like nonsense. Link?
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.
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.
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).
Quote from: RanulfC on 03/22/2012 12:35 pmNote 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.
Oh? Wow... Ok but first where did YOU come up with that idea for an airlock?
Quote from: A_M_Swallow on 03/22/2012 09:31 amWe 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.
Quote from: A_M_Swallow on 03/23/2012 11:20 pmThe 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.