#1
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Minimal space-suit
I've been wondering, just what is the minimum protection you can get
away with and still be able to function effectively in a vacuum? Say you're breathing pure oxygen at 2psi. That's a partial pressure of 1/3 below sea-level, which should be adequate providing you site the training facility on a mountain or dope your astronauts with Epo. If my math is on (flipping imperial system!) then the pressure at the bottom of a 4 foot column of water is about 2ps1. 4 feet is less than the distance from my heart to my feet. Therefore I hand-wave that the vascular system can support an internal pressure of 2psi without any outside help, and so, I'm guessing, can the skin. In that case, there's no actual need for a pressure suit. You ought to be able to get away with an oxygen mask covering the eyes, nose and mouth. So, the only additional problem I see is being able to expel air from your lungs at 2psi. I doubt this is possible, mind you. However, a tunic made out of some elastic material to squeeze the lungs (and maybe the stomach while you're at it, this could be uncomfortable otherwise) ought to suffice. Add a thermal-control overall to prevent you from frying or freezing, and voila... Or am I overlooking something? |
#2
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Minimal space-suit
James Moughan wrote:
I've been wondering, just what is the minimum protection you can get away with and still be able to function effectively in a vacuum? Say you're breathing pure oxygen at 2psi. That's a partial pressure of 1/3 below sea-level, which should be adequate providing you site Various places use 5PSI pure O2 as a second choice to sea-level mix. This corresponds quite well to the 4.6 PSI you need to get the same partial pressure of oxygen at the lung wall (there is water vapour and CO2 there too). In the article with message-ID: posted in april 2002, I posted the results of some sums. At 1.8PSI you'r groggy and weak, even if acclimitised. At 2.1PSI, more or less OK. snip vascular system can support an internal pressure of 2psi without any outside help, and so, I'm guessing, can the skin. In that case, there's no actual need for a pressure suit. You ought to be able to get away with an oxygen mask covering the eyes, nose and mouth. snip Or am I overlooking something? Yes. Fluid will rapidly pool in the limbs causing them to become swolen and useless. You need something to provide a pressure in the flesh that's high enough to squeeze the blood back from the extremeties to the heart. The skin usually does this, with the help of the lymphatic system. However, in space this won't work nearly well enough. However, do some searching on "skin suit". Basically, you use a tight elasticated suit to maintain a pressure over the body, hope the lymphatic system can iron out any minor inconsistancies, and don't pressurise the suit, only having a pressurised helmet. Gloves are a big problem, owing to the complex geometry. The torso is another problem, leading some to suggest just doing the limbs, and using a hard torso. -- http://inquisitor.i.am/ | | Ian Stirling. ---------------------------+-------------------------+-------------------------- Two fish in a tank: one says to the other, "you know how to drive this thing??" |
#4
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Minimal space-suit
Skinsuits have been posited by SF writers for some time. Niven I think did a
riff on them once or twice. A skin-tight membrane similar to a wetsuit contains the body under pressure, in some versions, it is semi-permeable to allow sweat cooling of the body. Usually in the stories a thermal and micrometeroid overgarment still is worn over it. It would make a fascinating experiment in materials science. Once you can make a suit so form-fitting as to become usable as pressure garment, how do you get into and out of it? Maybe it is painted on you? ;-) A tear in such a garment would probably make for an ugly wound, looking like what happens when you boil a kielbasa too long... |
#5
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Minimal space-suit
2psi without any
outside help, and so, I'm guessing, can the skin. In that case, there's no actual need for a pressure suit. You ought to be able to get away with an oxygen mask covering the eyes, nose and mouth. So, the only additional problem I see is being able to expel air from your lungs at 2psi Nope. The breath will rush from your lungs, but you can't *inhale* if you body is under vacuum. The water vapor and CO2 produced in the lungs has a partial pressure of 1psi; this will distend the thorax and make breathing movements impossible, besides which 1psi of oxygen is insufficient for human life. Bear in mind, oxygen masks deliver gas at *ambient* pressure. For Everest climbers this is 29,000 ft; in space, it is zero. Besides which, most of a body is water at 37C, and above 63,000 ft, water *boils* at 37C. Even if you could somehow get your breath, your blood vessels would fill with steam bubbles in a very nasty way. |
#6
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Minimal space-suit
In article ,
James Moughan wrote: Say you're breathing pure oxygen at 2psi. That's a partial pressure of 1/3 below sea-level, which should be adequate providing you site the training facility on a mountain... Not necessarily. What you care about is the partial pressure at the lung wall, not in the surrounding air. They differ because air going into the lungs is diluted by CO2 and water vapor coming out. That dilution is by roughly an absolute amount, *not* proportional to total pressure, so it affects thinner atmospheres more. So you need more than just a similar partial pressure. The Apollo suits -- which would have run at a lower pressure if they possibly could, for greater flexibility -- ran pure oxygen at 3.85psi. If my math is on (flipping imperial system!) then the pressure at the bottom of a 4 foot column of water is about 2ps1. 4 feet is less than the distance from my heart to my feet. Therefore I hand-wave that the vascular system can support an internal pressure of 2psi without any outside help, and so, I'm guessing, can the skin. Plausible reasoning, but the details don't work out. As little as 1.5psi excess pressure in your lungs, relative to your skin, involves serious risk of lung rupture. This is not just theory; scuba divers deal with this operationally. If you take dive training, you will get it hammered into you that you MUST NOT hold your breath even momentarily during ascent, because as little as 1 meter of ascent with a closed airway can become a life-threatening medical emergency. -- MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer first ground-station pass 1651, all nominal! | |
#7
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Minimal space-suit
"James Moughan" wrote in message om... I've been wondering, just what is the minimum protection you can get away with and still be able to function effectively in a vacuum? Say you're breathing pure oxygen at 2psi. That's a partial pressure of 1/3 below sea-level, which should be adequate providing you site the training facility on a mountain or dope your astronauts with Epo. If my math is on (flipping imperial system!) then the pressure at the bottom of a 4 foot column of water is about 2ps1. 4 feet is less than the distance from my heart to my feet. Therefore I hand-wave that the vascular system can support an internal pressure of 2psi without any outside help, and so, I'm guessing, can the skin. In that case, there's no actual need for a pressure suit. You ought to be able to get away with an oxygen mask covering the eyes, nose and mouth. So, the only additional problem I see is being able to expel air from your lungs at 2psi. I doubt this is possible, mind you. However, a tunic made out of some elastic material to squeeze the lungs (and maybe the stomach while you're at it, this could be uncomfortable otherwise) ought to suffice. Add a thermal-control overall to prevent you from frying or freezing, and voila... Or am I overlooking something? Two things. Partial pressure at 2psi is not enough. I believe you really need almost the full partial pressure of oxygen to make this work. In any case, google for skinsuit and you should find a bunch of research on this very subject. (note, the skin itself can handle even higher pressure differentials than 2psi. But there are other issues thta come up. |
#8
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Minimal space-suit
There are other factors to consider. The sunlight in space is ~7 times
brighter than on the surface of the earth, and completely unfiltered. Anyone lounging around in a tank top will get the worst sunburn of their life not to mention a raging case of leukemia or worse. this coupled with subdural hematommas over every exposed surface will make for a rather unhappy afternoon. See dick see dick go EVA without his pressure suit see dick go blind as his inner-ocular pressure blows his optic nerve out the back of his eyeball. see dick get a bad bad sun burn and funny lumps on all his major organs see dick get one REALLY BIG BRUISE over his entire body see dick gasp for air as his blood tries to take the path of least resistance out of his lungs dont be a dick, wear your space suit. -- "Yea, all israel have transgressed thy law, even by departing, that they might not obey thy voice; therefore the curse is poured upon us, and the oath that is written in the law of Moses the servant of God, because we have sinned against him." Daniel 9-11 "James Moughan" wrote in message om... I've been wondering, just what is the minimum protection you can get away with and still be able to function effectively in a vacuum? Say you're breathing pure oxygen at 2psi. That's a partial pressure of 1/3 below sea-level, which should be adequate providing you site the training facility on a mountain or dope your astronauts with Epo. If my math is on (flipping imperial system!) then the pressure at the bottom of a 4 foot column of water is about 2ps1. 4 feet is less than the distance from my heart to my feet. Therefore I hand-wave that the vascular system can support an internal pressure of 2psi without any outside help, and so, I'm guessing, can the skin. In that case, there's no actual need for a pressure suit. You ought to be able to get away with an oxygen mask covering the eyes, nose and mouth. So, the only additional problem I see is being able to expel air from your lungs at 2psi. I doubt this is possible, mind you. However, a tunic made out of some elastic material to squeeze the lungs (and maybe the stomach while you're at it, this could be uncomfortable otherwise) ought to suffice. Add a thermal-control overall to prevent you from frying or freezing, and voila... Or am I overlooking something? |
#9
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Minimal space-suit
James Moughan wrote:
I've been wondering, just what is the minimum protection you can get away with and still be able to function effectively in a vacuum? ... Or am I overlooking something? Interesting thoughts. As a mixed-gas diving instructor I have some thoughts regarding your post: First, please excuse my use of metric units instead of imperial. (For reference: 1 ATM = 14.7 psi ~= 1 bar) Normal ppO2 (partial pressure of oxygen) in sea-level atmosphere is 0.21 bar. A normal human can survive, without training, with 0.16 bar ppO2. With some training, this can be reduced to about 0.13-0.11 for a short periods, but this reduces also physical and mental performance. So, let's keep it in 0.16 bar, what is also the minimum accepted level in mixed-gas diving (while in rest). So, if you use pure oxygen instead of air, you can drop the ambient pressure to 0.16 bar, which is 1/6 of sea-level ambient pressure (1 bar, 1 ATM). But you can't drop the pressure suddenly. See: Decompression (Google etc.) Anyway, with proper decompression time you can be exposed to one sixth of sea level pressure, if you're breathing pure oxygen. And for short periods and some acclimation, you can reach even one tenth of sea-level pressure. But this is the limit, no matter what you do, without pressure suit. The vacuum conditions: If you are exposed to vacuum, there are some lethal aspects: 1) If exposed suddenly, you do need to exhale your lungs *fast*, otherwise your lungs will explode. Not like in horror-movies (cheast open), but you'll rip your lung tissue and get an embolia/emphysema. 2) If you survive above, then you'll have few seconds before black-out due to the lack of oxygen. 3) Keep your eyes shut. They are moist, and water evaporates (boils...) from the surface of your eyes. This happens also to your tongue and mouth. You won't freeze, even in cold space, for some time. Human body is water, and water has large heat capacity, and freezing to icycle takes some time. And you won't explode due to the internal blood pressure. Your lungs might, in worst conditions, if you don't exhale. Anyway, with some kind of "belt" in your chest, you still can't survive. While human propably can be exposed to vacuum for some seconds without "exploding", the pain due to the internal pressure could be awful. You do need full protection. And in space, you have to take the thermal aspects into account also. And possible radiation issue etc. So, in my opinion, the minimum space suit would be a suit that can take the one sixth of sea level pressure, and the suit would have a rebreather system to provide you oxygen and get rid of the carbondioxiode. Matti Anttila www.antti.la |
#10
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Minimal space-suit
"Matti Anttila" wrote in message ... James Moughan wrote: I've been wondering, just what is the minimum protection you can get away with and still be able to function effectively in a vacuum? ... Or am I overlooking something? Interesting thoughts. As a mixed-gas diving instructor I have some thoughts regarding your post: First, please excuse my use of metric units instead of imperial. (For reference: 1 ATM = 14.7 psi ~= 1 bar) Normal ppO2 (partial pressure of oxygen) in sea-level atmosphere is 0.21 bar. A normal human can survive, without training, with 0.16 bar ppO2. With some training, this can be reduced to about 0.13-0.11 for a short periods, but this reduces also physical and mental performance. So, let's keep it in 0.16 bar, what is also the minimum accepted level in mixed-gas diving (while in rest). So, if you use pure oxygen instead of air, you can drop the ambient pressure to 0.16 bar, which is 1/6 of sea-level ambient pressure (1 bar, 1 ATM). But you can't drop the pressure suddenly. See: Decompression (Google etc.) Anyway, with proper decompression time you can be exposed to one sixth of sea level pressure, if you're breathing pure oxygen. And for short periods and some acclimation, you can reach even one tenth of sea-level pressure. But this is the limit, no matter what you do, without pressure suit. The vacuum conditions: If you are exposed to vacuum, there are some lethal aspects: 1) If exposed suddenly, you do need to exhale your lungs *fast*, otherwise your lungs will explode. Not like in horror-movies (cheast open), but you'll rip your lung tissue and get an embolia/emphysema. 2) If you survive above, then you'll have few seconds before black-out due to the lack of oxygen. 3) Keep your eyes shut. They are moist, and water evaporates (boils...) from the surface of your eyes. This happens also to your tongue and mouth. You won't freeze, even in cold space, for some time. Human body is water, and water has large heat capacity, and freezing to icycle takes some time. And you won't explode due to the internal blood pressure. Your lungs might, in worst conditions, if you don't exhale. Anyway, with some kind of "belt" in your chest, you still can't survive. While human propably can be exposed to vacuum for some seconds without "exploding", the pain due to the internal pressure could be awful. You do need full protection. And in space, you have to take the thermal aspects into account also. And possible radiation issue etc. So, in my opinion, the minimum space suit would be a suit that can take the one sixth of sea level pressure, and the suit would have a rebreather system to provide you oxygen and get rid of the carbondioxiode. Matti Anttila www.antti.la How about a suit with tight leather straps all around - that should provide the pressure, but you'd still need some type of helmet in a vacuum. If you had a helmet with an O2 supply but no real suit, perhaps you could wrap some Duct Tape around your body, reaaaal, real tight (over your clothes ) and a jacket and snow pants or something similar over it - this could possibly protect the duct tape from coming apart due to exposure to the bright sunlight. In a pinch, it's better than nothing, I suppose. |
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