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View Full Version : Feasibility of Stillsuits


yBeayf
11-14-2003, 04:31 PM
A recent thread (http://boards.academicpursuits.us/sdmb/showthread.php?s=&threadid=223146) on eating one's own feces in a survival situation got me thinking: Are Dune-style stillsuits possible with today's technology, and if they are, how expensive / difficult would it be to construct one? For those who aren't familiar with Dune, a stillsuit is a suit covering almost all of the body, that collects all liquids excreted (sweat, urine, feces, moisture from exhalation), filters them, and delivers them back to the user in the form of potable water.

gonzoron
11-14-2003, 06:22 PM
I'm interested to hear people's takes on this one. For me, the tough part to accept was that it did all that using only the energy of the person's movements. I'd imagine that with a sufficient power supply, you could recycle enough to delay, but not totally prevent, dehydration. But I don't buy the perpetual motion aspect of it.

Ike Witt
11-14-2003, 06:55 PM
Stillsuits are not possible today, and I doubt that they would ever work. Have you seen the size of a sewage treatment plant? And those things don't produce potable water, they only clean it enough to release back into nature, AFAIK. If there was a simple technology that would make it possible for a stillsuit, it would be used in municipal plants first.

Plus, would you really want to spend any amount of time in a form fitting bodysuit that you defecate in? I know that I wouldn't.

bughunter
11-14-2003, 06:59 PM
It's not perpetual motion... you have to eat. This is an energy input.

And the fremen do drink water... they just pretend they don't need to.

With modern materials and processes, you could make one that recycled most of the urine, and some of the sweat, and maybe a little condensation from the breath and feces, but the suit would be nowhere near as efficient as the one Herbert depicts, nor would I make any guarantees about the palatability of the water, and you'd have to spend a lot of effort cleaning it out regularly...

Ick.

bughunter
11-14-2003, 07:01 PM
Oh, and it would also be prohibitively expensive, and require external power sources to operate.

Nothing's impossible, but not everything is practical.

CookingWithGas
11-14-2003, 08:47 PM
Science. Fiction.

ftg
11-14-2003, 10:04 PM
The real problem with stillsuits is fouling up shedding heat. How on Arrakis are you supposed to cool off if you're not evaporating water??? If the freemen have a low tech way of cooling off without losing water, recycling it would be a breeze.

Broomstick
11-14-2003, 11:01 PM
Strictly speaking, deserts don't have to be hot. There's nothing to keep the average ambient temperature of Arakis from being a chilly 3 degrees C, which would solve the whole heat problem.

Herbert never delved into the actual details of the stillsuits. Perhaps the recycling utilized some sort of engineered bacteria that would munch on the organic molecules in the urine and feces and excrete something drinkable, or leave something drinkable. Which would also solve the energy problem. Sort of.

psychomonkey
11-15-2003, 03:47 AM
Obligatory Red Meat link (http://redmeat.com/redmeat/2003-08-12/index.html)

Blake
11-15-2003, 05:24 PM
Originally posted by adam yax
Stillsuits are not possible today, and I doubt that they would ever work. Have you seen the size of a sewage treatment plant? And those things don't produce potable water, they only clean it enough to release back into nature, AFAIK. . If there was a simple technology that would make it possible for a stillsuit, it would be used in municipal plants first.

A tertiary treatment plant will produce water that is clean enough to drink. The whole aim of most tertiary plants is to reduce the faecal coliform load of the effluent to below that of the water source into which it is discharging.

Here is no place for stillsuit technology is sewage treatment. A treatment plan is designed to remove bacteria and requires vast amount of water to do so. A stillsuit is designed to remove water, and whether the effluent is sterile or not is irrelevant. They do completely different jobs.

Plus, would you really want to spend any amount of time in a form fitting bodysuit that you defecate in? I know that I wouldn't.

If it were a choice between that and death then I know that I would.

Originally posted by ftg
The real problem with stillsuits is fouling up shedding heat. How on Arrakis are you supposed to cool off if you're not evaporating water???

According to the Dune Encyclopedia, which I no longer own, the heat is shed as normal. The sweat soaks into an inner layer of cloth and evaporates just as it would if you were wearing normal clothes. The water vapour is then caught by a chemical in the next layer a few millimetres away. If anything the design would increase cooling because humidity next to the skin would always be close to 0.

'possum stalker
11-16-2003, 12:10 AM
It seems distantly possible until the "feces processed in the thighpads part..." I could conceivably imagine a membrane filter for sweat, or urine, but I can't even imagine a mechanism for handling solid waste.


Plus, would you really want to spend any amount of time in a form fitting bodysuit that you defecate in? I know that I wouldn't.


Reading Dune, I often chuckled to think of proud Fremen warriors crapping in their pants whenever the mood struck. I guess I'd rather spend my time in a form-fitting sewage-eating suit than a droopy, sagging one.

Mr. Excellent
11-16-2003, 01:58 AM
They wouldn't be "crapping in their pants whenever the mood struck." I can't remember which book it was, but at one point a character explains that one should never leave water in the stillsuit catchpockets, but drink it immediately, because "the best place to conserve water is in your body." For this reason, and the fact that solid waste excretion carries a water cost, I imagine that Fremen children would be taught to "hold it in" as long as practical to conserve water - the thighpads are a contingency option, but not the preferred one. Just my take, of course - your milleage may vary.

mmmiiikkkeee
11-16-2003, 03:23 AM
What would you do about the bacterial growth and resulting BO that would build up inside that kind of suit after like, 12 hours? Most people feel icky if they don't shower every day while wearing breathable cloths.

I think that what grew on the outside the body would be just as big a hassle as filtering what came from the inside of the body.

MonkeyMensch
11-16-2003, 03:31 AM
Mmmm.

Sietch Tabr. Smells like home to me.

scr4
11-16-2003, 04:19 AM
Originally posted by Blake
According to the Dune Encyclopedia, which I no longer own, the heat is shed as normal. The sweat soaks into an inner layer of cloth and evaporates just as it would if you were wearing normal clothes. The water vapour is then caught by a chemical in the next layer a few millimetres away. If anything the design would increase cooling because humidity next to the skin would always be close to 0.
This would merely transfer heat from the skin to the suit. It's the water vapor that carries the heat away, so if you recapture the water vapor then you are recapturing the heat as well. I think a stillsuit, if used in a hot desert, would need a powerful active cooling system to make up for this.

Bromley
11-16-2003, 06:51 AM
So the general consensus would be to use only at night and to have a Mad Max poop hole?

If heat retention was not a problem, solid waste was not recycled and you were only filtering what needed to be filtered to make the liquid not harmful, could all that be done using motion, a small battery and filters?

Also, could it every be used in a hot environment? If we go with the idea that Blake mentions and have the heat transferred from the skin to a layer within the suit, is there any way of ensuring that that heat was then passively shed outwards rather than either just sitting there and cooking us or being shed back in to the body? What we need is a heat Gore-Tex :) .

scr4
11-16-2003, 07:11 AM
Unfortunately a "heat Gore-Tex" (i.e. a material/device that passes heat only one way) would violate the laws of thermodynamics. So that's out.

If the air temperature is at least a few degrees below body temperature, you can use forced convection for cooling. That means using a fan. Your suit would need to be impermeable to water yet have high thermal conductivity; fortunately this is easy, a simple aluminum foil does the job. You'd also want to minimize radiative heating (absorption of visible and infrared light), but a simple parasol may suffice. In addition you need a fan to maximize convection (that's the "forced" part in forced convection.)

If the air temperature is higher but the exposure duration is limited (e.g. it gets cool/cold at night), you could use a material that can absorb heat throughout the day and "refreshed" overnight. Similar to what we use in coolers.

But I think it'd be easier to use an active cooling system and try to think of ways to obtain energy somewhere. In addition to temperature control, you'd need a heat exchanger to reclaim water which has evaporated from your body. If it's a hot desert you can probably use solar cells.

bordelond
11-16-2003, 09:02 AM
yBeafy, you the man (or woman)! I've been wanting to ask this question for the longest.

I know this won't stick to the Fremen stillsuit specs, but perhaps we can simplify the design to better accomodate what existing technology can deliver. Forget processing the feces. Forget processing most or all all of the sweat. Perhaps a feasible suit could be built collecting moisture from aspiration and from urine?

IIRC, the amount of moisture lost during aspiration dwarfs the amount of moisture lost from sweat, urine, and feces anyway.

bordelond
11-18-2003, 09:47 AM
Boy, I sure know how to kill a thread.

thewiz
11-18-2003, 11:44 AM
Why not use the recycled water to help cool the suit? I see microtubes running throughout the suit. Movement (especially in the knees and elbows) help pump and circulate the water. Chemical reactions in the storage areas cool the water. Before leaving, the user "primes" the suit with water. The amount expired is captured and added to the suit's reserves. Eventually, the suit would run out of water but a user could probably last for a few weeks at least.

chorpler
11-18-2003, 12:00 PM
I have a hard time believing that I lose more moisture from breathing than sweating, at least since I started taking this @#$% medication that makes me sweat buckets under the influence of any heat or exertion whatsoever. I've had to raise my water intake by half a gallon a day to compensate for the increase. (Anybody know of any anti-perspiration medications or creams or whatever out there? I've actually tried using conventional underarm anti-perspirant gel on my forehead and face, but that doesn't work. Maybe I should start a thread to ask about this...)

Anyway, I would be interested to find out how much water I lose from breathing, so I can see how that compares with the water I lose sweating, and also how it compares to what a normal person loses from sweating (which I assume is less than what I do).

bordelond
11-18-2003, 12:17 PM
Originally posted by chorpler
Anyway, I would be interested to find out how much water I lose from breathing, so I can see how that compares with the water I lose sweating, and also how it compares to what a normal person loses from sweating (which I assume is less than what I do).

This link (http://gorp.away.com/gorp/publishers/ics/hea_medb2.htm) suggests that I was wrong about water lost through respiration vs. sweating. However, it does seem that water lost during normal defecation is fairly minimal, so I wouldn't feel bad about skipping the fecal-processing issues of designing a working stillsuit.

Bromley
11-18-2003, 01:16 PM
Originally posted by thewiz
Why not use the recycled water to help cool the suit? I see microtubes running throughout the suit. Movement (especially in the knees and elbows) help pump and circulate the water. Chemical reactions in the storage areas cool the water. Before leaving, the user "primes" the suit with water. The amount expired is captured and added to the suit's reserves. Eventually, the suit would run out of water but a user could probably last for a few weeks at least.

That's the point. You heat the water up and need to shed that heat, but what chemical reaction allows you to do that? It has to be a reaction that can be maintained using something that is commonly available. In the desert, that's likely to be sun, sand, salts from your drippings and camel dung.

@chorpler. Start a thread on your question. As a fellow sweaty bastard I'd like to see if anything relevant to me comes up :) .

CalMeacham
11-18-2003, 01:17 PM
I don't care what youse all say -- a stillsuit sounds too much like wrapping yourself up in a plastic bag out in the desert, which sounds like a recipe for heatstroke.

bordelond
11-18-2003, 01:23 PM
Originally posted by CalMeacham
I don't care what youse all say -- a stillsuit sounds too much like wrapping yourself up in a plastic bag out in the desert, which sounds like a recipe for heatstroke.

I think an essential element of designing a working stillsuit is to allow open areas in which the skin can breath. It seems to me that not all the sweat need be reclaimed -- maybe only half of it.

bughunter
11-18-2003, 02:10 PM
The function of the large intestine is to remove water from the stool, anyway... why not let it do the job? It's pretty efficient as long as one is healthy. I know I've taken some poops I would have qualified as coprolithic...

I imagine Fremen would have adapted to maximize this efficiency.

(And I also imagine they would consider diarrhea to be the most dreadful of all afflictions... :eek: )

As for the rest of the suit, I've been with bordelond all along... it makes no sense to try and duplicate the fictional suit, but to establish some performance specs you know you can meet, and design to those.

Recovery of water from respiration and urine are probably the two easiest things. Sweat would be easy if there were an efficient means to collect it, but that would take some ingenious fabric design...

Cooling is indeed a problem. You need some sort of heat pump to perform condensation... either that, or use a reverse osmosis type filter.

And like I said, it's not going to recover 100%, but even 50% would reduce the water you need to carry by a significant amount.

GargoyleWB
11-18-2003, 02:28 PM
The fecal-processing burden on the suit would also be minimal. When the human body is running on the dehydrated side, the rate at which you...expunge?...solid waste drops dramatically.

As examples, I have a couple of friends who desribed in great detail how their poop-cycles changed while they were going through desert warfare training in the military. I'm sure that there are dopers around that could corroborate. They said that after the first big dump or two, they dropped down to about once every two weeks. Also, the consistency changed from the healthy squishyness that we are all accustomed to, to more of a pebbly/caramel like consistency. To quote my friend "I shat taffy kibble".

An episode of Survivor last season had one competitor remark that he only pooped once during the entire 3 week run he was on.

So I would bet that the "thigh pad processors" are really not critical to the suit's function and are more useful for storage and cleanliness than water reclamation.

badmana
11-18-2003, 02:33 PM
I believe NASA would be very interested in such a system. AFAIK they haven't be able to properly process feces into water without bulky equipment (I believe they burn it for fuel and extract moisture).

"stillsuites" would be best utilized in space, not in a desert. Heat transfer can be controlled (space is cold but isn't a very good for heat transfer). I would imagine such a system is possible if the suit covered the entire body and absorbed all moisture to be processed. The suit could also keep the lost salt inside the water to be ingested again (salt loss would also be an issue).

It probably wouldn't taste "good" and the suit would still have to shed some material that cannot be processed (feces and solid liquid waste) but probably would work to keep whoever alive much longer than without.

Also, if you use the motion of the body, wouldn't the extra work load on the person cause more water to be shed, thus requiring more work to process the water? I think solar power would be a better subsitute.

bordelond
11-18-2003, 02:37 PM
Originally posted by bughunter
Sweat would be easy if there were an efficient means to collect it, but that would take some ingenious fabric design...

Collecting the sweat can be made loads easier by not attemptig to collect all of it -- just some of it.

Gravity can do some of the work -- perhaps there can be material at the forehead, neck, wrists, waist, lower thighs, and ankles that collects sweat. Think sweatband material.

lokij
11-18-2003, 05:50 PM
It seems to me that everybody is making some assumptions about a 'stillsuit' like technology that might not be necessary. I get the impression that alot of people think that a 'stillsuit' is supposed to be form fitting, and that it's development depends on advances in materials science alone. I think a looser fitting, multi-layered garment utilizing bio-engineered symbiotic bacterias as well as smart materials and nanotechnology could make a water reclaimation and waste processing suit with a high degree of efficiency. It might even be solar powered to some extent and provide the wearer with a food source through artificial photosynthesis, a compact little ecosystem that you wear and are a part of.

bughunter
11-18-2003, 06:24 PM
There are no unnecessary assumptions. The OP was pretty clear.

The question from the OP:
Are Dune-style stillsuits possible with today's technology, and if they are, how expensive / difficult would it be to construct one? That's "Dune-style" and "today's technology" -- not an exact functional replica of a Fremen stillsuit using hypothetical technology.

Yes, it could be Dune style. No, it wouldn't work as well as in Frank Herbert's vision. And yes, it would be expensive, and anywhere from somewhat difficult to extremely difficult depending on which wastewater products it needed to recycle.

DocCathode
11-18-2003, 10:31 PM
RE-Heat

I can't recall the name, but cloaks are worn over the stillsuits. They allow heat transfer in one direction only. During the day, they're used to dissipated body heat. At night, they're used to keep warm. The cloaks can also be fashioned into tents in case of sand storm.

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