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?

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??"

(James Moughan) :

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?

You just re-invented the skinsuit. Check out:

http://yarchive.net/space/science/skinsuits.html

http://www.google.com/search?&q=skinsuit+vacuum

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SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to
the time? http://webhome.idirect.com/~earlcp

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...

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.

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! |

"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.

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?

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

"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.