You are not logged in.
Terraformer wrote:
Clear tubing, filled with clear water?
It might be made to work in theory, but the complexity of making it in situ and maintaining the system seem prohibitive to me.
I am researching the properties of Kevlar. Does anyone know how transparent Kevlar sheets could be? It has a flaxen tint it seems.
Also, what is the rate of decay for Kevlar under UV radiation? Does anyone know or know where to look?
Offline
I personally have a favorite type of UV protection on mars. It is called sunscreen. More precicely, Homosalate, octinoxate, octisalate, oxybenzone.
http://en.wikipedia.org/wiki/Homosalate
etc.
or more generally:
http://en.wikipedia.org/wiki/Sunscreen# … ngredients
just puttinga coating of any of these on the dome fabric would allow it to be very protective.
-Josh
Online
I personally have a favorite type of UV protection on mars. It is called sunscreen. More precicely, Homosalate, octinoxate, octisalate, oxybenzone.
http://en.wikipedia.org/wiki/Homosalate
etc.or more generally:
http://en.wikipedia.org/wiki/Sunscreen# … ngredientsjust puttinga coating of any of these on the dome fabric would allow it to be very protective.
Interesting idea. Is this true for UV-A, B, and C? How long would it last? How thick would it need to be provide protection and how much would this reduce transparency?
Offline
Clearly sunscreen is very effective,, so a layer of this tuf in its pure form a few mm thick should effectively remove the UV. According to wikipedia, most of the compounds don't decay at all, and can increace insolation in the dome by emitting light at lower wavelengths.
-Josh
Online
Possible spacecraft radiation protection usage?
"I'm gonna die surrounded by the biggest idiots in the galaxy." - If this forum was a Mars Colony
Offline
jumpboy11j wrote:
Clearly sunscreen is very effective,, so a layer of this tuf in its pure form a few mm thick should effectively remove the UV. According to wikipedia, most of the compounds don't decay at all, and can increace insolation in the dome by emitting light at lower wavelengths.
I like this possibility, although I worry that even a few mm will really obscure more visible light than would be needed. I wonder how transparent it can be made. I hope it could be so designed.
Terraformer wrote
Possible spacecraft radiation protection usage?
I think the radiation of most concern is X-rays and cosmic rays rather than UV and so sunscreen would have less applicability, right?
Offline
Yes, but I assume (very dangerous thing to do, assuming) that the way it blocks UV could be altered to screen out other wavelengths.
"I'm gonna die surrounded by the biggest idiots in the galaxy." - If this forum was a Mars Colony
Offline
here's one type of dome construction that should not be forgotten:
http://www.calearth.org/EcoDome.htm
I think they'd also look good on Mars.
Using sandbags to fill with sandy regolith is a quick way of creating building material and uses no industrial processes as such. Lifting the bags would be easier in third gravity, though maybe you would need more of them to create a pressure seal?
Not sure about the cement rendering, as to how easy that would be to produce on Mars. You'd need a lot of cement!
Let's Go to Mars...Google on: Fast Track to Mars blogspot.com
Offline
I'm not sure if someone has brought this up yet, but what about the possibility of anchoring a dome with buildings (obviously not for agricultural domes). Tension members could link the top of the dome to the base of a building on the ground.
This would be most practical with highrises in the dome, but I figure that with the limited space and less gravity, higher density buildings only makes sense. Several tall buildings would provide more than enough weight to anchor the dome, as well as a large amount of open space (assuming concrete structure, concrete density of 2400kg/m^3 and g of about 3.67).
Any thoughts?
Offline
One problem with using concrete as the Biosphere 2 crew discovered is as it hardens it absorbs air.
I know this was a little ways back in the thread, but I wanted to correct it by quoting a letter to Science:
A Small Misconception
Regarding "Carbon sink: A clue from Biosphere 2?" (R. L. Walford, Science's Compass, 15 Jan., p. 330), I want to clear up a small misconception that has been widely repeated in the press (and also in the Perspective by J. E. Cohen and D. Tilman, 15 Nov. 1996, p. 1150), namely that "carbon dioxide [CO2] was combining with the cement of the structure, carrying oxygen along with it to form calcium carbonate... hence the fall in oxygen concentration." The cement in Biosphere 2 did not cause the oxygen loss. It is true that the CO2 reacted with the cement and that CO2 contains oxygen atoms. But it is molecular oxygen (O2) rather than oxygen atoms that was being lost from the air in Biosphere 2. The amount of oxygen atoms present in the water in Biosphere 2 is about 200 times more than the amount of oxygen atoms present as O2, so the loss of oxygen atoms to the cement was insignificant. Rather, what caused the O2 loss was the excess of organic matter in the soil, which supported an imbalance of O2-consuming respiration over O2-producing photosynthesis. The reaction of CO2 with the cement only made it a little harder for us to find the true cause of O2 loss, by scrubbing from the air the telltale product of respiration, CO2.Jeff Severinghaus
Scripps Institution of Oceanography,
University of California, San Diego
"Everything should be made as simple as possible, but no simpler." - Albert Einstein
Offline
Thank-you Midoshi for the correction
Chan eil mi aig a bheil ùidh ann an gleidheadh an status quo; Tha mi airson cur às e.
Offline
I think we need to understand that a Biosphere has very little to do with a Mars habitat. A Mars habitat won't be a closed self-regulating eco system. It will be an externally supported eco system - energy, resources and raw materials will be drawn in from outside the habitat and certain waste products will be vented into the exterior.
Let's Go to Mars...Google on: Fast Track to Mars blogspot.com
Offline
Thread Necro, I've been thinking of the combination of inflatable domes and sprayed-on ridged expanding foam insulation. This would be vastly simpler then making a dome by any other method as the materials would consist of just an inflatable balloon (probably Tyvec), tanks of the foam chemicals and a sprayer/wand tool. Spraying is a well established method to spread insulation inside houses today and it should be possible to adapt it for use in the cold and low pressure of Mars, a two chemical approach is generally used with the chemicals mixing as they are sprayed. Note that the floor will require more insulation then the roof as the solid ground represents a vastly larger heat-sink then the thin air, floor panels laid on-top of the insulation would be sufficient to walk on it.
The other huge benefit of expanding foam is it's thermal insulation, when in such a cold environment maintaining the habitable environment at reasonable temperature is key, these closed cell foams have the highest insulation values of anything used in the home market. With the dome acting as the primary thermal and wind barrier the construction inside the dome would be considerably simplified. Additional regolith coating could provide more insulation value but it's efficiency per unit of mass will be considerably lower and it might require additional heavy equipment to move that out-ways it's benefits.
I would NOT recommend trying to pressurize the dome directly, rather pressurized tent structures would be placed inside along with airlocks. One or more secondary passages in the dome itself provide access to the surface and these secondary passages are ware dust control measures are taken. The secondary passages isn't air-tight but it should be able to block wind and keep the warm but unpressurized dome air from mixing with the outside air, a small positive pressure inside the dome helps keep the dust out as well. This keeps all the internal tenting and airlock stuff isolated from dust and eliminates most the need for it to insulate which means the tent can be cheap and simple plastic and their should be no condensation on the inside tent wall.
I think a dome of this type could scale up to considerable size, the limiting factors are really just the ability to safely spray the rigid foam. If a high pressure spray gun, a long sprayer arm/boom and a modest scissor-lift were available I'd suspect something like 50 meter diameter domes could be built. If the dome was thick enough and the slope gradual enough for it to be walked on then theirs effectively no limit, but I doubt this would be practical or safe. Still a 50 meter dome is a considerable volume and about 2000 square meters of floor space with potential for secondary floors. Naturally this technique would work on the Moon as well.
Offline
There's something wrong with the format in this thread. Everything recent is indented out of view to the right. There is no way to scroll over to read or respond.
I could not figure out how to post a bitmap image here, so I posted it at http://exrocketman.blogspot.com. It shows the layout and structural equations for a pressure dome structure retained by gravity.
GW
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
Offline
The column format error is a carry over from the older Phpbb legacy conversions and while it is possible to fix the admins are absent....
The image for the bitmap would need to be converted to be posted as that was an earlier board feature....
In either case structures of any kind for mars is a must....
Offline
Impaler,
I like your work. I think layering is a good notion. The idea that one wall does all is a starter, but when you look at the Martian environment your solution where layers handle different challenges, I like it.
I am not interested in playing topper, but I will just mention some of my thoughts, and you are certainly able to make of them what you will or will not.
-I have thought of glass "Scales" attached to a lizard skin, and the skin of fabric/film over a frame. However, I think this will be too labor intensive.
-I will suggest the addition of an expendable "Epidermis" for your shelter. As it appears that the shell-dome you would make will be rigid, it will have some of the properties of a tent frame. You could consider draping a expendable tent over it, and litterally using tent pegs to fasten the edges to the ground. I would suggest that this flexible film would be coated with a protective coating of glass spray. It would be change out and recycled periodically, perhaps ground up and used as filler for a new rigid dome, when it had deteriorated from the harsh outer Martial environment. It would also create yet another layer of themal insulation. I am merely offering the suggestion. Economics and technology would determine if this is a value added process, or simply a drag that you don't need.
-My enclosures with compression of air have typically been sausage links of netting holding in a bladder of compressed air. Some advantages, some liabilities. The links would need a method of connecting the ends as "Junctions".
I hope this does not annoy you that I jumped in with this stuff.
But I do like your method to construct a hard dome shell, that is not pressurized. It makes a lot of sense to me.
Last edited by Void (2012-06-10 09:57:17)
Done.
Offline
I had an idea concerning how to build aboveground pressurized structures that address the radiation, cold, and near-vacuum issues in an appropriate design approach. These could be places in which to live, garden, and farm, depending upon size. There are at least a couple of supporting technologies not yet in-hand, but they could be, soon, and I tried to identify them all. This concept is not for first missions. It's for permanent bases or settlements. I wrote it up and posted it over at http://exrocketman.blogspot.com, as the article titled "Aboveground Mars Houses", dated 1-26-13. Enjoy.
GW
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
Offline
Yes, agree, I am really struggling to read this page. The formatting is messed up with all the encapsulating quotes. There needs to be a limit of how many quotes can be encapsulated.
So I did not see the solution for how to protect the dome from radiation. UV protection but how? Can something UV protecting be manufactured on Mars using locally available material?
Offline
With the need for processed ore for making feed stock for the 3 D printer it would seem that we need to look at what mars has to offer.
Mining Mars? Where's the Ore? and from the great images Rocks on Mars A variety of rock types and sediments have been found on Mars. Many are similar to rocks on Earth.
So what would be the mineral processing priority and selection?
Iron Ore Mining which includes the BlueBerry
Minerals on Mars Olivine belongs to a class of minerals that possess distinctive olive-green coloration, a translucent luster, and a hardness greater than glass.
Martian Mineralogy: Important Minerals for Understanding Geological Processes on Mars
Of course we want the water, silica and other such materials that will be there when we go after other minerals that are in that higher priority index....
Offline
Just like the Minimum Acceptable Net Habitable Volume for Long-Duration Exploration Missions table we will need much of this stuff even on Mars surface as well..
The proposed volume of 25 m3 is consistent with previously proposed volumes
7 functional areas were identified:
1. Berthing, or sleeping space/private quarters : The volume for each individual crew quarters is 5.4 m3 but ISS crew quarters are, by comparison, 2.1 m3
2. Dining and communal activities : sufficiently large space to simultaneously fit all 6 crewmembers, Includes a window with a portal (~ 0.5 m3) as a way to visually extend the social space and provide an important countermeasure for psychological health.
3. Work space : Sized to allow up to 4 crewmembers to focus on meaningful work or activities simultaneously
4. Exercise (area can also accommodate EVA suit donning and medical care) : Allows for 2 exercise devices to be used concurrently
5. Hygiene : Provide volume for at least 2 separated hygiene and waste compartment areas
6. Translation portals or pass-throughs : Function-thin partitions for visual and acoustic separation, Assumes additional volumes for pass-throughs and transition paths, Adequately sized for a suited crewmember
7. Stowage access : Point-of-use stowage is included in all areas, Assumes crew of 6
Offline
I wonder if water would make a great sealant for the dome material. Lets say instead of a complete sphere half buried, we use half a sphere, and bury the edges under the regolith, the average temperature for most places under ground on Mars will be below freezing, pump some water down their to create some permafrost. create a permafrost layer underground, completely under the dome, and as you get closer to the surface under the dome, the soild temperature will go above freezing, that way we can retain soil moisture for growing crops. How much area of ground under the dome do we need to feed a crew of four on a sustainable basis, do you think? Like the movie The Martian, I think if we don't bring pests or weeds, agriculture may prove simpler and less labor intensive under the dome than on Earth.
Offline
I remember Zubrin discussing the use of permafrost as a construction material in Case for Mars. It would seem to be a reliable solution but does depend on abundant water. One way to use it to good efficiency would be to anchor your dome deep underground using cables. Then inject superheated high pressure steam into the bore holes to freeze the anchors into the surrounding bed rock.
One idea that occured to me and doubtless others before, was a gravity balanced dome using hollow adobe tubes with a glass lense on the inside. The long tubes when assembled into a dome would resemble a porcupine. The gaps between the diverging tubes could be filled with unprocessed regolith adding to the counterweight. Such a dome would admitt plenty of light as the internal surface would be mostly glass and apart from the glass lenses would be constructed entirely from non-stabilised Martian regolith.
Offline
About 2 percent of the soil on the surface of Mars is made up of water of if you heat up a cubic foot of Mars soil, you can harvest around two pints (one liter) of water with Earth having more than 10 times that amount.
Of course any dome made of a frozen soil needs to be sealed and insulated from the warming interior that Humans would create inside it. That said the outside would also need a sealant to keep that warming water from subliming away while in the days sunlight to keep it solid of which I would make the outer sealant white colored in order to reflect the heat from being obsorbed by the darker soil color.
Offline