The use of hydrostatic pressure on Mars.

Void · 2012-03-17 11:32:22

In the past, I have made attempts to suggest at various websites that a good way of pressurizing a habitat is to have it at the bottom of a lake. Of course on Mars having a lake requries significant work. However the reason I am posting this is the hope that I could get feedback on why I never got what I considered a serious answer on the notion. I really don't care if it is ever done, it annoys me that I don't think that I ever got a killer reason why it shouldn't be attempted.

In the past, I did get the notion that Mars is completely Arid, and that a pool of water would simply sink into the rigolith.

Here is a link which suggests that this may not be true if you are in the northern or sourthern half lattitudes (And I susspect that if you had a supply of water that it could be done at lower lattitudes as well).

http://science.nasa.gov/science-news/sc … artianice/

The notion as put forward originally included emulation of Dry Valley Lakes in Antarctica. But on Mars manipulation of the environment would be required.
In it's present condition, it would be needed that a supply of make up water be available at a location accessable.
-Ice must cover the lake. To protect the ice from sublimination, mechanical means are required. (See articles on this site about IceCrete). I generally expect that a vapor barrier covered by a layer including glass windows is required (Just a little pressurization might be prefered).
-Salt in the water is prefered. In that condition the bottom of the lake could well experience terrestrial temperatures. (Google for Antarctic Dry Valley Lakes).
-Generally the notion of living underwater is not practicle, on Earth. Why do it. if you can walk about on the surface. On Mars, however, this equasion of preference does not hold true.

If I had an arcificial dry valley lake on Mars, I could:
1) Put on a swim suit suitable for a man (In order not to scare people), and have a breathing apparatus and go out in the bottom of the lake and touch a rock with my bare hands, and hold a handful of soil with my bare hands. I might expect the possiblity of temperatures I could endure, or even be comforatable with.
2) Build an arch type stone structure under the water on the bottom of the lake, and fill it with air, and cover it with soil so that the bubble of air within it did not explode it with boyancy. I would then have a underwater "House".
3) Dig tunnels under the lake into the rock. Create habitats there.
4) Perhaps have photosynthisis occuring in the cold layer of relatively fresh water just under the ice. With gentic engineering perhaps have crops growing there, production of food.

Anyway, I am fearful of the notion of glass domes, pressurized. The slightest break, and the pressure leaks out.

Hydrostatic pressurization is not like that. A leak means that sublimation is slowly taking the ice layer away that covers the liquid water (Which would scab over with ice if exposed to Martian Pressure). This would be a thing that could be addressed before lethal conditions occured.

Anyway, I am wondering what is against this set of notions?

Last edited by Void (2012-03-17 11:58:17)

John Creighton · 2012-03-18 00:22:47

Void wrote:

In the past, I have made attempts to suggest at various websites that a good way of pressurizing a habitat is to have it at the bottom of a lake. Of course on Mars having a lake requries significant work. However the reason I am posting this is the hope that I could get feedback on why I never got what I considered a serious answer on the notion. I really don't care if it is ever done, it annoys me that I don't think that I ever got a killer reason why it shouldn't be attempted.
In the past, I did get the notion that Mars is completely Arid, and that a pool of water would simply sink into the rigolith.
Here is a link which suggests that this may not be true if you are in the northern or sourthern half lattitudes (And I susspect that if you had a supply of water that it could be done at lower lattitudes as well).
http://science.nasa.gov/science-news/sc … artianice/

The notion as put forward originally included emulation of Dry Valley Lakes in Antarctica. But on Mars manipulation of the environment would be required.
In it's present condition, it would be needed that a supply of make up water be available at a location accessable.
-Ice must cover the lake. To protect the ice from sublimination, mechanical means are required. (See articles on this site about IceCrete). I generally expect that a vapor barrier covered by a layer including glass windows is required (Just a little pressurization might be prefered).
-Salt in the water is prefered. In that condition the bottom of the lake could well experience terrestrial temperatures. (Google for Antarctic Dry Valley Lakes).
-Generally the notion of living underwater is not practicle, on Earth. Why do it. if you can walk about on the surface. On Mars, however, this equasion of preference does not hold true.
If I had an arcificial dry valley lake on Mars, I could:
1) Put on a swim suit suitable for a man (In order not to scare people), and have a breathing apparatus and go out in the bottom of the lake and touch a rock with my bare hands, and hold a handful of soil with my bare hands. I might expect the possiblity of temperatures I could endure, or even be comforatable with.
2) Build an arch type stone structure under the water on the bottom of the lake, and fill it with air, and cover it with soil so that the bubble of air within it did not explode it with boyancy. I would then have a underwater "House".
3) Dig tunnels under the lake into the rock. Create habitats there.
4) Perhaps have photosynthisis occuring in the cold layer of relatively fresh water just under the ice. With gentic engineering perhaps have crops growing there, production of food.
Anyway, I am fearful of the notion of glass domes, pressurized. The slightest break, and the pressure leaks out.
Hydrostatic pressurization is not like that. A leak means that sublimation is slowly taking the ice layer away that covers the liquid water (Which would scab over with ice if exposed to Martian Pressure). This would be a thing that could be addressed before lethal conditions occured.
Anyway, I am wondering what is against this set of notions?

I think it will be difficult to live under water but it would certainly be worth trying. Not only would this give an alternate way of life on mars but it would open up new areas of earth. I suspect underwater construction is difficult.

SpaceNut · 2012-03-18 08:26:13

Underwater habitats created from a large valley covered some how with a covering/ dome to house a base for life to exist.

Well a closed in bubble of water gets around the triple point caused by the weak martian gravity and creates a radiational barrier as a plus.

The habitat can be modelled after that of a submarine's systems for life support once you have a reactor but until then the base would be power starved to make many a system work for protective the crew.

GW Johnson · 2012-03-18 10:00:36

It is certainly possible to live under an ice-covered artificial lake on Mars. That requires building the lake (earthmoving, and ice-mining activities, plus energy to liquify the ice). Then you live inside the equivalent of a submarine hull, able to venture outside with a wetsuit and scuba gear. But, you are restricted to the lake, unless you dress for what amounts to vacuum as far as the body is concerned.

Why not just build the equivalent of the submarine hull on the dry surface and bury it with dirt for insulation and radiation shielding? It's less total construction activity, and less earthmoving in particular. To go outside, dressing for vacuum does not necessarily require a gas-balloon-type suit. Mechanical counterpressure garments with a gas breathing helmet rig have existed since the late 1960's.

These do not need to be one piece garments. You could doff the compression gloves for up to about 10 minutes at a time, if barehanded work could be done without mechanical or thermal injury risks. Depends on how sharp and how cold the dirt and rocks are.

Although, for recreational and agricultural purposes, being able to go outside down in a lake would be very nice. And, would that be a good environment in which to grow food? That's the easiest way I can imagine to pressurize and wet-down very large areas: under an ice-covered lake. It takes large areas to grow food for people.

Hmmmm. Intriguing idea.

GW

Void · 2012-03-18 15:06:08

I didn't know that gloves could come off that way for up to 10 minutes at a time. I bet if feels funny, and perhaps not all that good for you, but sometimes delicate work has to be done. Thats something.

Well, your responses were far more kind and generous than I was expecting.

And hopefully you will not mind if I expand the conversation around this subject.

Here is a link to such a lake in Antarctica:
http://en.wikipedia.org/wiki/Lake_Vanda

A nuclear reactor in the habitat at the bottom of the Lake would make sense, because if it were carfully managed, it could perhaps dump heat into the lake.
The lake would also be a direct solar collector. However, Mars of course does not have the same solar flux, perhaps > 1/2 that of the Earth, and also subject to dust
storms.

I do make the point that extra heat could be dumped into the bottom of the lake by boiling water in solar concentrators distrubuted around the lake, and then turning
a turbine, and quenching the steam directly into the lake water. So, the lake would serve the utility of being a part of a condensation process, and and also as a
energy storage, method, since during the nights, (And the terrible cold winters at higher lattitudes), the lake could serve as a source of heat to drive a different
boiling process where Ammonia might be boiled. Of course this implies metal radiators to dissapate the heat, and recondese the ammonia at the surface. However, I
have been contemplating cisterns inside of sheds filled with an Ammonia/Water mixed solution, to again quench the Ammonia steam. The cisterns might actually be
hollows in the ground with stone/tile floors and walls, and inside of that bags suitable to tollerate the solution and also the temperatures. The purpose of the
sheds would be to protect the bags from UV light during the day, and also to shade the condenser bags, and I suppose to keep the abrasive dust of the Martian
environment at bay to a degree. The sheds might have an open wall though facing the polar direction, to allow heat to radiate out, or perhaps just a transparent
layer of "Plastic film". Whatever that would be, it would be desired that it had the minimum greenhouse effect and let heat radiate out of the bags.

So, the nuclear power might be an small part of the power sourcing, but desired, in case of a major fault on the solar driven power system.

So, with much electricity, it becomes reasonable to think about a large industrial infrastructure. I suggest that this would be implemented in tunnels in sandstone
or other rather soft rock, under the lake. Of course some processes would work better on the surface in buildings built there.

I think that such tunnels would actually be a good place to grow fruit trees under artificial light. The artificial lights would be modulated in accordance with
power availablity, since trees are used to illumination variance due to clouds and changing seasons. Thus this would be a load leveling method, a method to utilize
scrap power, when there was an excess of power. The interesting thing is if it was apple trees, you could let the tunnels cool down and perhaps put in very little
light during the winter. However, I am not sure what the apple trees humor would be about having seasons twice as long. This would then be food, and wood, and also
"Parks" for people to spend leisure time in. So this could have significant value.

In the end my dream would be to fill the entire Northern basin back up with an ice covered sea. However the transformation to this situation would be long and hard.
I could mention several impediments to that. Such as the likelyhood that there is not enough water available to fill that flat baisin to 100 feet deep, and there
is no certainty that it would be a salty body of water. If it were to be, then the salt would have to exist under the soil, a remnant of the ocean that existed
Billions of years ago.

However if achieved, then the point northern condensation would be captured, and any ice and snow condensation would be melted from below, the solar concentrators ubiquitous on top of the ice layer. In such a case, I would presume terraformation at that point would have created an atmospheric pressure of at least 10 to 20 millibars. The need to shield the ice from sublimation would be reduced or eliminated, since you would have a continuous source of make up water from the condensation on the surface of the north pole, which would be continuously melted from below.

The I would expect a lesser sized ocean covered with ice, and likely not as salty as I would prefer. However, it would be easy to dyke off "Polders" to fill with properly salty water, to allow for bottom water of 23 C (73 F) and more.

Trucks that were partially boyant but traveled under the ice would be an option. They actually could run on roads on the bottom of the Ocean/Sea/Lake, or perhaps
could be very boyant, and connect to rails, under the ice, attached to the bottom of the ice surface. Subs? Yes.

Last edited by Void (2012-03-18 15:16:49)

GW Johnson · 2012-03-18 15:29:57

Void:

I was thinking a bit smaller than you, just how to get started. At first I was skeptical, then, when the aquaculture angle occurred to me, I was won over. My background is many decades as a real, practicing engineer, but I am not a one-specialty guy (a rarity in more than a century now). Basically skeptical, I am hard to win over. And with good reason.

I was thinking about ice-covered lakes, and ran a few numbers for depth versus what I know about life support. If the pack ice plus regolith cover is about 6 meters or so, you have sufficient hydrostatic pressure on your body to safely approach the bottom of the ice pack without a pressure suit. That means pure oxygen scuba is practical and safe, to depths (on Mars at 0.38 gee) of around 18-20 meters below the 6 meter cover (the 1 atm partial pressure O2 limit). Below that, one needs diluent gases in the breathing mix.

These things will be too well-covered to absorb significant solar energy, even at Earthly fluxes. But artificial sunlight will be required to run photosynthesis, and its waste heat can help keep the lake unfrozen. I'm thinking a simple, transplanted, Earthly aquaculture in the lake (too bad we haven't yet developed one).

This lake idea may be the most practical way to bring pressure and oxygen to large areas on Mars to support farming. Sure beats trying to come up with gigantic transparent pressure domes. I like it.

Anyhow, I wrote it up and added a concept sketch, and posted the lot over at http://exrocketman.blogspot.com, with due credit to correspondents like yourself. It's the article posted 3-18-12, titled "Aquaculture Habitat Lake for Mars". Should be near the top as most recent.

GW

JoshNH4H · 2012-03-18 23:53:19

I think that the biggest potential problem with the lake idea is that there are truly very large amounts of water required to make it work. 18-20 meters is quite deep. Further, the loss of natural sunlight does make it a lot more expensive to grow crops. For regular habitats I think regolith makes more sense because it's cheaper and denser.

It's still an interesting concept, though, and an idea at least worth giving some thought.

Void · 2012-03-19 08:35:52

GW Johnson

Well, thanks! I have carried this for a very long time, and am pleased to pass it on in some form. It is old for me, so I have further options to describe.

JoshNH4H
I prefer a shake out, to be forced to be "Real" so thanks as well. Of course now I will continue.

Much of Mars will never be covered with water. The parts that make the most sense to cover at this time have the qualities of being suitable to hold a water cover, and also haveing large quantities of ice, and also the biggest prise is the precipitation which will always be dominantly at the polar ice caps (Until the axis of Mars changes in several 10,000 years).

So actually there are several options, and in my view they should all be used. However walking about in a pressure suit on the surface of Mars is going to be for adults only with rare exceptions, and such adults will have to be of a competent mind and in excellent health, and well trained. Even with that there will be risks such as radiation, so it would not be a prefered activity, just at times necessary. I would think that when possible avatar type virtual reality systems would be prefered over that when they could acctually acomplish a certain task.

I am guessing that a minority of Mars will ever be covered with water, and so the rest will require "Dry" methods. However if we capture the percipitation of the poles and create a reservoir that both is involved in energy production and having a large reservoir of water, then it is reasonable to draw water from those reservoirs, and "Pipe/Canal" it to locations dry to use as may be economically productive.

As for the layer of ice being too thick, the Dry Valley lakes in Antarctica do have photosynthisis in the top layers. The nature of those salty lakes is that the top layer is colder, and fresher, and has Oxygen in it. The lakes being isolated, they havea very limited number of species. Otherwise without the isolation, I expect that complex plants would have evoved to live there. However Photosynthis is limited. There is no point in acting like that is not true. The thickness of the ice could actually be thinner in places, to promote Photosynthisis, but of course then divers would have to be very careful not to get too high in the water column. Special safety measures would have to be employed. Keep in mind that under some circumstances ice can be much more transparant than we typically experience in our Temperate Earth Environments.

GW Johnson,

Although I have mentioned above that Photosysthisis does occur in the Dry Valley Lakes of Antarctica, I agree that it would be a weak boilogical system, perhaps strengthened by biological engineering to produce plants that are complex, and make the best use of the wavelengths available.

However I more favor Chemosynthisis. Methane seeps, Hydrothermal vents. All replicated artificially. Oxygen supplied, Chemical foods supplied, by industrial processes. Shellfish could extract calcium from the water which would disolve from the soils. The shells becomming a resource, perhaps for concrete?
Some of these life forms as food.

It is also true that the bottom of our ocean under the soil supports a living system without sunlight, just off of the reactions of chemicals, and from what I understand, that is very powerful. I don't know if some of it's properties of life would emerge into the water as well, but I am thinking it would.

Also I do support the use of transparent domes at low pressures, so that plants of a land type could be grown. Again, I am guessing eventually crops would be available which could be grown at 50 millibars, 20 Millibars and whatever, and so those domes could be pressurized accodingly to grow such a crop to produce bulk plant matter, and again in this case, waste plant matter could be dropped into water pools to support life. If these low pressure domes produced an excess of Oxygen, then that also could be injected into the water pools to support life.

Safety and also the happiness of humans: I see the value of creating some small very safe and rugged domes where humans could experience "Parks" the parks could have skylight sections where they could sit under the stars and moons, or sun themselves. However a safety feature might be a deep pool of water with an exit on it's bottom (And emergency Breathing apparatus at the bottom as well). If the dome became dangerous due to a drop in pressure or fire, or bad atmosphere,
then I presume well maintained alarms would direct them to dive into the pool and seek safety at the bottom.

Thanks much.

Last edited by Void (2012-03-19 12:37:32)

JoshNH4H · 2012-03-19 14:26:12

I'm not going to say that any of your suggestions are impossible, because they are very clearly not in violation of the laws of physics. It just seems to me that they are extremely implausible given that they require planetary engineering on a significant scale. Further, it is important not to conflate the goals of an initial colonization project with a long-term terraforming project. Terraforming, if it is desired at all, will likely not start for a fair amount of time (if at all), and the colony will likely not care if the minute changes to the environment of which it is capable serve to make it more earthlike.

I don't think that building pressurized structures will be too much of a hassle. It won't be easy, but it will be entirely doable. I think you also overestimate the risks of radiation; people likely won't be spending excessive amounts of time in the greenhouses because they will probably be largely automated and will be done on a rotation.

The ability to go outside in a spacesuit is going to be absolutely vital. I suspect it is a skill that people will be taught early on and will become expert at by an early age, rather like riding a bike on Earth. Martians will almost certainly use mechanical counterpressure suits, which are much easier to put on, take off, and maneuver in than the spacesuits used today.

Actually, I wonder. Do you guys think that bikes have a place on Mars? I think that there are definitely situations where it could make more sense to don a spacesuit and bike over to where you're going than to go to all the trouble of getting in an enclosed car-like vehicle and get there, probably much more slowly than you would otherwise.

Void · 2012-03-19 16:05:25

The profit margin is what matters.

I have edited my first response. I think I can do better.

It is a matter of prereferences. You could put forward the "It's my or the highway" attitude, but I might say, that there are various places and conditions on Mars, and I am not an enemy of pressure suits, especially counter pressure suits.

However there will be two budgets. One will be for maintainence, and one will be for expansion.

I really do not think that large money will be expended from either budget so that small children can hang out outside of the habitat. It would be spent on suits, so that well prepaired adults could do real and necessary work needed for survival and profit.

If that society were to work it's children, I would expect their chores would be mostly indoors.

And I do believe that it is unwise to have children accumulate radiation exposure before they have been raised and have become old enough to have had their children.

Outside would best be reserved for rational adults past prime, and still physically fit.

And I do believe that the best future is avatar machines, with which all persons including children could experience the Martian surface, such as smelling it, and seeing it in ultra violet light, and so on.

I actually have notions on a radically different type of Robot/Avatar. However it would be for heavy and crude work, but would compliment and also support the robots that NASA has been doing work on. The logic of it's structure is quite different.

So, you see a person and a child person as well, could do work from within the habitat, perhaps running a avatar/robot, and it could be structured like a video game, and not made into some repugnant task. (Although usually we make our own realitys a hell by our lack of perception of what truely matters).

And further, that child could in the same day swim in a diving bell filled with air at the bottom of an ice covered reservoir, and could in addition travel in a submarine, and could in addition run an underwater avatar, and could walk from one settlement to another in an underground tunnel lighted artificially, and filled with apple trees.

Not exactly being locked up in a tin can is it?

But returning to people working outside, the necessary work would be done by the most cost effective and morrally acceptable methods.

Last edited by Void (2012-03-19 21:20:50)

JoshNH4H · 2012-03-20 13:03:55

I absolutely agree that the most cost-effective method to do a task will be the method of choice. I just contest whether or not your proposed method is the best way to do things because of the high resource cost.

Walking around in an MCP suit is not actually very difficult. Most work will be inside, since that is easier, but as a basic matter of safety every person in the colony will have to be able to handle a suit. I would imagine that even with parks and farms going out to the surface will be considered rop be something good to do on the weekend.

Void · 2012-03-20 15:07:09

I am going to yield points to you. I had a look at some info on the suit, and I like it. (I read of such things long ago, but was not aware of current activities by MIT).

http://en.wikipedia.org/wiki/Space_activity_suit

However I am still going to say that I think that the ethusiasm is overdone. For instance if I was on Mars in one, and took my gloves off in the daytime, I might both freeze my fingers, and get my skin fried off by UV light (Big blisters in no time). However, that would be stupid, and I expect that their would be some type of protective cover or device.

Also, scuba divers do die from time to time, equipment failures, but as you imply, making the use of it from childhood could yield a population with a second sense about saftey with it. But it would still be risky business.

The other thing is that new things get old, especially in an abrasive environment with UV, and with natural aging, and mechanical wear. Maintaining safety margins is an unknown expense, and will be untill it is tried. The cost effectiveness of "Playing" outside would need proving.

I expect that from the time a real used working suit were demonstrated, the technology would improve and improve. As I said I can see a winner finally in the end if you give me time.

Still, I see no reason to abandon the notion of using the ice and water resources of Mars to a maximum benefit, altering the static condition where most water sits at the poles, to one where it is available dynamically. Particularly since I have shown that it can be integrated with certain power systems tied to the heat of the sun and the cold of the polar winters.

I do see the possibility for instance (Which I bet you will throw rocks at) where indeed greenhouses could be constructed on a large scale with a minimum necessary pressure, to grow some bulk vegitation, and to produce Oxygen. It is to be noted that a large body of cool water can hold significant Oxygen, and so then can serve as an Oxygen tank. Further, bulk vegitation could be dropped into such a reservoir, for cold blooded livestock to feed on. (Fish, filter feeders), and as I have mentioned, filter feeders could secrete shell from the waters, the minerals disolved in the water would provide what they need for that perhaps.

The counterpressure suits would make this type of industry more practicle.

Or prerhaps an advanced technology will allow skipping the fish, and simply making soilent green from the bulk vegitation.

Anyhow, it appears that most of our clashing is due to lack of communications, perhaps I could listen more, and you could present more details, and perhaps you might consider just a little more flexible thinking before making a decision. (If you want to).

I hope that is not too rude.

Last edited by Void (2012-03-20 15:11:34)

Void · 2012-03-20 15:22:17

I decided to separate this out, because I am interested in it specifically.

What about air locks? Can they be safe? Over time with wear?

For Polar Conditions with abundant water:
Because of my decompression phobia, I have felt that for instance a person emerging from a shelter would be best off to enter a reservoir of water and to emerge upwards into a partial pressure chamber. Perhaps 10-50 Millibars, depending on the temperature. A "Lid" would then be closed on the vertical door that the person emerged through, and then the partial pressure chamber would be decompressed and a horizontal door would be opened allowing access to the outside.

For "Tropical" conditions with sparce water:
I have to say I imagine it could also be done with brine very cold, so that the "Partial Pressure" chamber could actually stay at ambient. Instead of an air lock, it would be a "Vapor Lock". The person would emerge up, and close the lid. The the dry cold walls in the chamber would collect the moisture. Then the horizontal door would be opened. From time to time the "Vapor Lock would be heated up and the frost vaporized, and that being sucked into a compressor, to recapture the water.

The point of all this being that a water column does not require a pump so much, in the case of minimizing losses of O2 from the habitat.
I am aware that some very clever methods have been considered for baisically sheet metal doors that slide. But those imply dumping the contents of the airlock out.

I am also wary of the abrasive nature of the Martian environment as currently reported (These facts have a tendency to change over the years, so I am also aware of that).

So I am not wild about metal parts used over and over again for air locks. High maintenance and high risk I am thinking.

This time I will put up with what I consider abusive dismissal, as long as you understand that I won't consider myself dismissed.

I baisically need to have an outlet for this, and perhaps an opportunity for update, and then I consider I will be retired from an obligation to promote these alternate ideas, and can move on to more current and pleasant ideas what ever they might be.

So, thanks, for the opportunity to talk and get it done.

Last edited by Void (2012-03-20 15:24:42)

Void · 2012-03-20 16:18:22

Just some interesting stuff, I could intrude elsewhere with it, but why. It kind of fits here, and this thread is likey to go silent soon anyway.

http://www.universetoday.com/93059/larg … d-on-mars/

http://www.universetoday.com/91848/new- … tain-life/

JoshNH4H · 2012-03-20 22:49:50

Void- First of all, your posts were not rude in the slightest. I hope that I have not come across as rude. My short posts were not supposed to be dismissive so much as brief, because I did not have much of actual substance to add to the conversation; Seeing as water and irrigation are not easily comparable in cost to moving regolith without an actual Martian economy being established, I can only offer my feelings on the matter. If I am going to offer an unsubstantiated opinion I feel it's best for me to not disrupt the conversation with a long post.

On spacesuits, it's an art that could certainly bear a lot of improvement. We're just stating to see new work on them now, even though they've been largely similar since the 60s (Though modern spacesuits last longer and are probably a little easier to use, they are fundamentally the same as they were 40 years ago). I expect that we will see a lot of improvement in the coming years. I know that a suit very similar to the one being proposed as a MCP suit was limber enough that you could swim in it (e.g., the "supersuits" which were ubiquitous in the 2008 Olympics). I think that these suits have a very good potential to be very durable and very safe, as well as very easy to use.

While taking off your glove in such a suit would be an exceedingly bad idea, it would perhaps not be quite so bad as you suggest (While there would be bruising and possibly a sunburn, the atmosphere is too thin for its temperature to have any physical effect and one would likely not lose usage of the hand). I think that this is an example of an "exception that tests the rule" with regards to the safety of an MCP suit. That taking off a glove is a good example of what injury could befall a person in this kind of suit IMO demonstrates that they are on the whole pretty safe. So long as the helmet remains in place, even a small tear in the suit material will just cause a localized bruise and not death or significant injury.

I have no issue with low-pressure greenhouses, so long as it can be demonstrated that plants can survive at the pressures within that greenhouse. I would point out that as the pressure gets lower, it also becomes easier to make a more standard Glass-and-Steel greenhouse.

Airlocks are a particularly sticky problem. The internal pressure of the habitat will probably be 40-50 kPa. You can preserve an arbitrarily large amount of air by allowing it to escape into what is essentially a balloon, and then drawing it back in when you want to re-pressurize. To preserve 90% of your air without using some kind of pressurizer to shove it into the balloon, you need a balloon 9 times as large as the airlock. To preserve 50%, you need a balloon of equal size. I think that the best solution to minimize losses is to have a variety of airlock sizes, so that when people go outside they do it individually in an airlock hardly bigger than one person. Another solution is to fill the airlock with CO2 (make sure you step in quickly) so that the gas that is lost is not as valuable.

The latter strategy could perhaps be combined with the use of a pool of water that the suited individual could swim through. This would reduce the diffusion of CO2 into the main habitat, which is certainly a good thing. The colonists could dry off their MCP suit in the airlock chamber (A waterlogged suit is never good, especially if it started to freeze while outside, which could happen because unlike a body part it does not continuously have warm blood flowing through it. This would make the wearer very cold, as well as making the suit degrade much more quickly.) Compressing the CO2 would be energy intensive, but not nearly so much so as creating Nitrogen or Oxygen.

I know this doesn't speak to your concerns of metal wearing out or degrading, and those are legitimate concerns. But everything has a service life. If it makes a difference, it should be possible to cover the heavy equipment so that the dust doesn't get in the way of anything too badly. Because the dust is composed of Iron oxides it should be somewhat magnetic, and it might be possible to keep it away from important things by placing magnetite elsewhere.

I don't favor the idea of using a column of water as an airlock for a couple of reasons. Firstly, that requires that, for every airlock, you build a tower 11-14 m (calculated) high to contain the water. Secondly, it makes it very difficult to get big things into and out of the colony's structures. I would probably just go with a more-or-less traditional airlock for that. To be fair, your suggestion does not make that impossible as you were specifically talking about an airlock for people. In any case, I think a smaller active system for people is probably going to be less resource intensive than a tall tower (though it's an interesting idea; anyone else have a position on this?). I think it's worth noting that the top of the column of water will either freeze, evaporate at a pretty high rate, or both. I think it's also worth noting that a loss of pressurization on either end could have some pretty catastrophic effects.

In a general sense, I would like to point out that the idea of building a canal several thousand kilometers long is going to be completely beyond the ability of any martian colony for quite a while. In fact, the planetary engineering you're suggesting is more something that would be done for terraforming than for a simple colony. There are plenty of smaller bodies of ice near the equator that can be mined for use by the colony. In fact, there's an entire frozen sea (800 km by 900 km and 45 m deep) near Elysium.

Void · 2012-03-21 11:51:21

We seem to have a differnce in time scope. I am less concerned about the original establishment than the most powerful outcome.

I trust that people like you will work out the details of the first "Dry" settlement. It almost has to be such.

However, I am pleased to see that you innovated and added a potential water trap to your airlock.

The only way a first settlement would make sense in deep water is if a fision reactor were landed into a large body of ice, and melted into it, and if it then deployed methods to facilitate life, such as a Chemosynthis system, developing a pool of water filled with Oxygen and food. Then the people would land, and have food, power and Oxygen.

However, I don't think it is a best way.

I think your methods are the best for the start. However, I think that capturing and controlling the large bodies of ice at the poles and converting them to ice covered reserviors, are a very good objective to work towards.

I am not against greenhouse gasses. My understanding is that the poles should contain enough CO2 for a 10 Millibar average pressure to exist. Obviously this fits just fine with stabalizing the surface of cold ice, to decrease sublimination.

The pathway from First dry settlement to Polar Reservoirs might be decades long or longer. It might involve artificial salty dry valley lakes in the temperate zones, before getting the poles under control.

After the poles were under controll, an economy where water is moved in canals is reasonable. Particularly for the Southern Hemisphere. I believe that that ice cap is at high elivations, and Hellas is very low, so, gravity flow is reasonable. But you are correct this would be an action that a rather mature an powerful Martian society with millions or ever billions of people would be involved with.

As for the Vertical water column airlock. I agree not for the original dry methods. However, if you have a reservoir, and put a little dome on top of it you can pressurize it from 6-60 millibars as desired using outside atmosphere. (I think 6 to 12 might be enough if it is fresh ice water. 6 would be enough if it is a very cold brine).

The dome would have a hatch you entered from the side, for access to the lake surface, and it would have a hatch on it's bottom for access to the lake.

So at very maximum, if the dome pressurized to 50 millabars, it would take care of 1/20 of the pressure differential to 1 bar pressure inside the lake water column. The water column would take care of 19/20 of the differential.

If you used 11 milliabars for the pressurization, with the horizontal door closed and the floor hatch open (To ice water), then the dome would only carry 1/200 of the pressure differential. (More or less).

This mostly only makes sense if your object to access is inside of the lake. Perhaps a stone building on the bottom of the lake, perhaps a tunnel enterance to a underground facility, an entrence with either an air lock or a trap like a sink trap.

I like the idea you communicated about a balloon to capture air lock air.

John Creighton · 2012-03-21 12:45:25

Well, there are certainly some large challenges in the topic presented let me offer some intermediate prospects which are less challenging. The first is that you only need a 14 m column if the air lock is in one stage. Alternatively you could have 14, 1m columns and 14 stages. While this this may seem like a lot for of a person to go though it provides a very continuous transition for moving materials in a conveyer belt like fashion and would not have the same mechanical ware as a conventional air lock. There is of course nothing stopping people from using such a system (time permitting).

Multiple stages may be motivated by how the colony decides to expand and work. Hard structures may be preferred for living spaces but soft inflatable structures may enclose working spaces making it easier to build structures, reducing the requirements for the pressure suite and providing an extra level of safety for the hard structures.

If there is mining for either material or habitation reasons than a water reservoir could be used as a safety mechanism to provide containment pressure for the tunnels in the case of depressurization. For surface structures, like tunnels between domes, inflatables could be used to act like a check valve to provide some shutoff ability in the event of depressurization. They would work under the principle that when the pressure drops the gas inside the inflatables would expand which would effectively reduce or stop pressure losses. Manual or automated doors could further seal the tunnel if necessary.

Last edited by John Creighton (2012-03-21 12:45:39)

Void · 2012-03-21 16:47:43

That is exactly good. What is needed in my opionion is a catalog of options, as well as a plan of which to use when. But of course that has to allow some flexability.

I am very happy to learn of other options. Sometimes it takes a while for me to comprehend deeply however. But when I finally do grasp something it is integrated into the catalog, and then when possible linked to other ideas, sometimes with success, and sometimes not so much. Trial and error then.

One little trick I have tried to work on is a greenhouse inside of a greenhouse.

The first one holds a pool of sterile water, because we would not want micro-organisms to grow there and block the light. The first one would be at ambient Martian pressure, but with a significant humidity inside of it. It would frost up inside at night, and then the frost would evaporate (I hope, and condense elswhere on a surface of Ice I hope. It would have a layer of transparent ice inside of it covering a pool of water. However within that pool of water would be a second greenhouse. That second greenhouse might have a layer of air 1 or 2 feet thick (Sorry for the archaic units). And warm water under the air layer. Floating plants, and swimming perhaps. However the two might not be compatable. If you wanted to grow floating plants, then perhaps you would want a column of water and ice 5 to 10 (Or more) feet thick, since you would want the minimum blockage of light. Duckweed is an option, a more cool water plant. However Hyacynth is not out of the question.

Again this is for the circumstances of a plentiful supply of makeup water from local ice.

The plants could be collected and directed to a deeper body of water to feed livestock (Fish, filter feeders).

For swimming, the layer of water in the first greenhouse needs to be deep. Perhaps 32 feet (Sorry again).

The 2nd greenhouse should not be made of glass. Plastic. I believe that glass has poor mechanical properties in water, but very good in a vacuum.

As for the collapsable tunnels you have suggested, I am curious. Can you give details? Or a diagram?

As JoshNH4H suggested or seemed to suggest:
The most valuable greenhouse would be one where ambient pressure could support actual rooted plants. Perhaps in the Hellas Depression at the best pressures avaiable, with a genetically engineered plant? Then as has been suggested we could have plant growth with a simple greenhouse and some moisture to the roots. However the plant would have to tollerate being watered with ice water.

Perhaps other people could come up with a better plan for this.

Perhaps it would be like rice but the water it was in would be ice water. This would help to compensate for the cold nights, if the ice water did not freeze and damage the plants.

Last edited by Void (2012-03-21 17:06:54)

New Mars Forums

Announcement

#1 2012-03-17 11:32:22

The use of hydrostatic pressure on Mars.

#2 2012-03-18 00:22:47

Re: The use of hydrostatic pressure on Mars.

#3 2012-03-18 08:26:13

Re: The use of hydrostatic pressure on Mars.

#4 2012-03-18 10:00:36

Re: The use of hydrostatic pressure on Mars.

#5 2012-03-18 15:06:08

Re: The use of hydrostatic pressure on Mars.

#6 2012-03-18 15:29:57

Re: The use of hydrostatic pressure on Mars.

#7 2012-03-18 23:53:19

Re: The use of hydrostatic pressure on Mars.

#8 2012-03-19 08:35:52

Re: The use of hydrostatic pressure on Mars.

#9 2012-03-19 14:26:12

Re: The use of hydrostatic pressure on Mars.

#10 2012-03-19 16:05:25

Re: The use of hydrostatic pressure on Mars.

#11 2012-03-20 13:03:55

Re: The use of hydrostatic pressure on Mars.

#12 2012-03-20 15:07:09

Re: The use of hydrostatic pressure on Mars.

#13 2012-03-20 15:22:17

Re: The use of hydrostatic pressure on Mars.

#14 2012-03-20 16:18:22

Re: The use of hydrostatic pressure on Mars.

#15 2012-03-20 22:49:50

Re: The use of hydrostatic pressure on Mars.

#16 2012-03-21 11:51:21

Re: The use of hydrostatic pressure on Mars.

#17 2012-03-21 12:45:25

Re: The use of hydrostatic pressure on Mars.

#18 2012-03-21 16:47:43

Re: The use of hydrostatic pressure on Mars.

Board footer