Date: 7 Jan 90 23:14:00 GMT
From: cs.utexas.edu!jarvis.csri.toronto.edu!utgpu!utzoo!henry@tut.cis.ohio-state.edu  (Henry Spencer)
Subject: Re: Simpler space suits?

In article <641@halley.UUCP> watson@halley.UUCP (William Watson) writes:
>3)	Maintain a "suitable" air pressure over the entire body of the
>	wearer.  (Is this actually required, in that cells exposed to vacuum
>	burst, or die in some other way?)  This requirement forces the
>	design to be quite complex...

Maintaining pressure on the body surface is unfortunately necessary.
Exposure to vacuum does not (contrary to folklore) have any immediate
disastrous effect, as skin really is pretty tough stuff.  However, the
loss of pressure causes gas to be generated internally, which causes
swelling to start after a few seconds.  Initial swelling is reversible
with no ill effects, but later stages undoubtedly do permanent harm.
Eventually the major body fluids will boil.

A significant side issue is that pressures inside the lung and outside
the chest must balance fairly well, else breathing will be impossible
(and lung damage is possible).

It is possible to maintain *pressure* without *air pressure*, however,
using what are essentially very tight and strong leotards.  The skin is
exposed to vacuum, but swelling and other ill effects are prevented by
mechanical pressure.  This concept works; it has been tried in vacuum
chambers.  Problems remain, and more work would be needed to produce a
viable spacesuit based on it, but it appears likely that a much less
restricting spacesuit could be built along those lines.  The early work
was funded by NASA; no work is currently being done on it.

>5)	Protect the wearer from exposure to intense solar radiation.
>	(First cut approximation:  assume near-Earth use - UV induced
>	melanoma seems to be a concern...

So is sunburn.  Naked skin exposed to raw near-Earth sunlight will start
to burn in something like 30 seconds, as I recall.

>6)	Protect the wearer from micro-meteors.  (Is the flux of high-speed
>	sand significant?  Does the current design really provide any
>	effective protection?)

The current designs provide considerable protection, with a substantial
outer suit that is basically thermal insulation plus armor.  My guess,
made without checking the numbers, is that natural debris is not much
of a concern, but in low orbit the man-made junk is a real issue.

>7)	Be comfortable enough that the wearer can stay in the suit for
>	extended periods of time.  Extended wear also implies methods
>	for feeding and relieving the wearer.

Such means are currently rather primitive, actually.  Today's suits do
have minimal provisions for water and food, but "relief" is basically
via a high-tech diaper.  Well, the male astronauts have a relief-tube
arrangement for urine, but that doesn't work for the females, and there
just ain't no graceful way to deal with crapping in a suit.  "Extended
periods" currently means 4-6 hours at most.  The diaper is mostly for
female urine and, uh, sudden emergencies.
-- 
1972: Saturn V #15 flight-ready|     Henry Spencer at U of Toronto Zoology
1990: birds nesting in engines | uunet!attcan!utzoo!henry henry@zoo.toronto.edu

Date: 23 May 87 23:58:45 GMT
From: mnetor!utzoo!henry@seismo.css.gov  (Henry Spencer)
Subject: Re: Erythropoietin for extra blood O2 capacity

> Gee what about human heat?

Cooling is done the same way it is here on Earth:  sweat.  The S.A.S. does
not seal the body inside an impermeable bag, remember.

> What about water transport?

I'm not sure what water you are referring to.  There is no water cooling
system such as conventional spacesuits use.

> You are basically right about pressure and about joints being a problem,
> but please don't over simplify by creating a straw man in NASA.

Well, read NASA CR-1892, "Development of a Space Activity Suit", by
James Annis and Paul Webb, and tell me what you think.  (Note to people
asking me about references:  this is the major one.)
-- 
"The average nutritional value    Henry Spencer @ U of Toronto Zoology
of promises is roughly zero."     {allegra,ihnp4,decvax,pyramid}!utzoo!henry

Newsgroups: sci.space.policy
From: henry@spsystems.net (Henry Spencer)
Subject: Re: Space "Capsule" Space Suits... a possible alternative?
Date: Wed, 19 Jan 2000 21:43:20 GMT

In article <Dp9e4.687$vL5.13002@news2.jacksonville.net>,
William Icquatu Jr. <equation@gnr.net> wrote:
>>By the way, the suit itself may be "unpressurized" in the sense that there
>>is no air in it, but it has to supply *mechanical* pressurization to the
>>skin.  You can't have the lungs at significantly higher pressure...
>
>does this mean the skin in its' totality (from head to toe) or is the
>pressure balance requirement only over the head and chest area?

All of it.  Remember, a fraction of an inch below any part of the skin
there is blood, which is connected through uninterrupted plumbing to blood
in the lungs.  Pressurizing one area of the body more than another just
squeezes all the blood out of the overpressurized area, for starters.

>>>...seals against the neck and chest areas, allowing pressurization of the
>>>atmosphere in the helmet to 15 psi -- normal sea level pressure.
>>It's doubtful that this is possible, at least not without some serious
>>magic in the fabric...
>
>I understand the difficulty in articulating joints and providing adequate
>tactile sensation under pressurization -- even under the nominal 3 psi
>differential in current shuttle suits -- but why would there be a problem in
>a case where there is no difference in pressure between the interior of the
>suit and the outside?

The whole skin *must* be pressurized to more or less match the air
pressure within the helmet.  The inside/outside pressure difference is not
optional.  The fact that the pressure is being supplied mechanically
rather than through air does change the exact nature of the problems, but
it doesn't eliminate them.

Tailoring of the suit is critical, as are the exact properties of the
fabric.  For example, tailoring a glove which can apply an even pressure
of 15psi without distorting the hand unbearably is not simple; that's
quite a lot of pressure (equivalent to a column of water 10m high!) if
it's squeezing your hand the wrong way.  It's been done at 3.5psi, but the
outfit which did it -- they normally design pressure garments for treating
burn victims -- concluded that their techniques couldn't be pushed to
8psi, let alone double that.

>    2)  provide the necessary pressure to maintain lung integrity as the
>bladder would be pressing against the structure of the carapace on the
>outside and the chest area of the wearer on the inside... the carapace does
>not have to stop at the chest, it could cover the entire abdomen and lower
>back as well.

Note that you don't need a rigid carapace for this -- the NASA skinsuits
simply used a bladder within the stretch fabric to provide for lung
inflation, as I recall.  Small air-filled shaped balloons were also the
solution to providing mechanical support for various concave areas of the
body.  (They didn't work perfectly, and that's one of the unresolved
problems.)

>    4)  within certain limits, provide a true 'one size fits all'
>application for suits, as inflation is adjustable depending on the wearer...
>as an added benefit, the carapace would fit quite snugly once the bladder is
>inflated... if the entire suit is 'hard' enough, every segment (arms/legs
>etc) could have an airmat lining, and enjoy the same advantages...  in
>addition, as each segment has its' own (semi)independent airmat lining,
>there should be few if any serious problems with joint articulation... the
>benefits of a pressurized suit, witout the drawbacks...

The more closely this approximates a conventional pressurized suit, the
more closely it will duplicate the problems of the pressurized suit.  In
particular, you can't avoid the joint problems just by waving your hands
about independent segments.  If those bladders are butted up against each
other inside the carapace, they *will* be at the same pressure as each
other, and you've got the same old problems.  If there are gaps between
them, how do you pressurize the skin under the gaps?
--
The space program reminds me        |  Henry Spencer   henry@spsystems.net
of a government agency.  -Jim Baen  |      (aka henry@zoo.toronto.edu)

From: Doug Jones <random@qnet.com>
Newsgroups: sci.space.tech
Subject: Re: Non-pressurized "pressure suit"?
Date: Sat, 18 Mar 2000 00:18:26 -0800

Bruce Behrhorst wrote:
>
> I tend to think the idea although sounds good
> is a tough workable senario. A skin tight
> wetsuit type "space girdle" to balance the
> vacuum envio. has to be tough to squeeze
> into. Your asking someone to step into a
> suit strong enough withstand 0 psi and erratic
> tempertures and expect the body to feel comfort at
> 15psi and also the subject has to bend to
> perform tasks.

I seem to recall pics of 40s-50s vintage partial pressure suits which
used bladders along the arms and legs (apparently at lung pressure) to
draw the garment tight only when pressure was applied in the helmet and
lungs.  Presumably similar features could be built into advanced
skinsuits to allow a reasonably loose fit while donning or removing, but
good pressurization in vacuum.

> Arteries/veins need the
> right mix of pressure (pressure on the heart)
> this would be cutoff in a full body wetsuit for
> space applications unless you provide the
> circulation would not be in constriction.

I can visualize how excess pressure on the extremities could reduce
circulation, while insufficient pressure would allow bloating... but
small local blood volume increases would serve to equalize the pressure
as the elasticity of the garment would raise the local pressures.

The wearer would probably adjust helmet pressure to get best comfort and
fit- if the gloves feel tight, increase helmet pressure, if the hands
feel bloated, reduce helmet pressure.  Certainly the skinsuit would
require some attention and care on the part of the wearer.  Flexing
muscles and doing some stretching exercises could help prevent edema and
blood pooling.

> Just how would you guarantee the subject
> won't passout in 15min. of activity in space?

I started to dismiss this, then on further thought I think that it may
be possible to have a dangerous amount of blood pooling in the
extremities if the helmet pressure is too high.  Tensioning bladders
connected to the helmet would help ensure constant pressures, even if
the wearer has gained or lost weight, or has eaten a large meal.
Dehydration can reduce total blood volume substantially, so the bladders
would provide volume makeup along with the pressure balancing.

The elbows and knees could be problematical- the bladders must be
discontinuous, or else you're back to the flexibility problems of
conventional suits.  This might make the elbow and knee joints
difficult, and I have no idea how hips and waist bending would work...
I'm not saying that it isn't doable, just that I don't know enough about
it, and some of the problems appear pretty tough.

Given the moribund state of skinsuit research, I doubt if they'll be
useful anytime soon.

--
Doug Jones
Rocket Plumber, XCOR Aerospace
http://www.xcor-aerospace.com

From: henry@spsystems.net (Henry Spencer)
Newsgroups: sci.space.tech
Subject: Re: Non-pressurized "pressure suit"?
Date: Sat, 18 Mar 2000 18:57:53 GMT

In article <38D1AAC7.B21CA59D@indra.com>,
Charles R Martin  <crmartin@indra.com> wrote:
>I'm more concerned about the effects of exposing the decending colon to a
>sudden 1 atm pressure differential.

Folks, do note that such suits *have been made* and real people have worn
them in vacuum chambers.  Nothing awful happened.  The suits did have some
problems -- funding ran out before solutions could be explored -- but the
basic concept definitely does work.

Note also that the suits done so far do not pressurize to 14.7psi; they
use a pure-oxygen atmosphere at circa 3psi in the helmet, and matching
mechanical pressure in the suit.

I suspect that the anus is being sealed fairly effectively and so there
is no issue with pressure differentials across the digestive tract.
--
Computer disaster in February?  Oh, you |  Henry Spencer   henry@spsystems.net
must mean the release of Windows 2000.  |      (aka henry@zoo.toronto.edu)

From: henry@spsystems.net (Henry Spencer)
Newsgroups: sci.space.tech
Subject: Re: Non-pressurized "pressure suit"?
Date: Sat, 18 Mar 2000 19:07:25 GMT

In article <38D37FFD.284E45D8@cableinet.co.uk>,
Matt Jackson  <Mattjackson@cableinet.co.uk> wrote:
>Another thing; wouldn't it lack the insulation which is provided by
>conventional suits?

You'd wear an insulating overgarment, but it would not be pressure-tight,
indeed it would be vented.

>Even with their chunky gloves astronauts risk frostbite in their fingers
>if they stay out too long.

Not really; there was no problem with this on the Moon, for example.

You're probably thinking of a few shuttle tests which were run in
deliberate worst-case conditions, to establish whether there might be a
problem in spacewalks constrained to occur in cold conditions.  (For
example, on the station you don't get to point the cargo bay at the Sun or
the Earth to help keep spacewalkers warm.)  They concluded that there was
a problem, but heated gloves and some other small changes solved it.
--
Computer disaster in February?  Oh, you |  Henry Spencer   henry@spsystems.net
must mean the release of Windows 2000.  |      (aka henry@zoo.toronto.edu)

From: henry@spsystems.net (Henry Spencer)
Newsgroups: sci.space.tech
Subject: Re: Non-pressurized "pressure suit"?
Date: Thu, 23 Mar 2000 03:17:24 GMT

In article <Pine.MAC.4.10.10003210004560.4404-100000@kapu.net>,
Michael J Wise  <mjwise@kapu.net> wrote:
>The bigger question is, if you had nothing but a space-helmet, sealed
>around your lower jaw (not the neck, obviousely), and a small source of
>breathable mix, what would kill you NEXT?

Lung rupture.  Scuba divers have to be very careful not to hold their
breaths during ascent.  It only takes about 1.5psi difference between
lungs and outside to kill you.
--
Computer disaster in February?  Oh, you |  Henry Spencer   henry@spsystems.net
must mean the release of Windows 2000.  |      (aka henry@zoo.toronto.edu)

From: Doug Jones <random@qnet.com>
Newsgroups: sci.space.tech
Subject: Re: Non-pressurized "pressure suit"?
Date: Fri, 24 Mar 2000 21:18:42 -0800

Michael J Wise wrote:
>
> Ian Stirling wrote:
>
> > > The bigger question is, if you had nothing but a space-helmet, sealed
> > > around your lower jaw (not the neck, obviousely), and a small source
> > > of breathable mix, what would kill you NEXT?
> >
> > Your lungs exploding.
>
> First question: To where do they explode?

With no counterpressure on the extremities, the blood volume pools
there. Then the alveoli expand into the network of (now-empty) blood
vessels, or the pleural spaces, and burst.  Your bloodstream turns to
foam and alveoli soup.

From http://www.mtsinai.org/pulmonary/books/scuba/sectionf.htm (SCUBA
DIVING EXPLAINED by Lawrence Martin, M.D.):

    1) Escaped air can dissect along tissue layers into the area
       known as the mediastinum, the large space between the two
       lungs. Once in the mediastinum, the air can go into spaces
       around the heart (but not in it), into the neck, and into
       spaces around the abdominal organs.

    2) Escaped air can rupture through the visceral pleura (thin
       membrane that lines the lungs), resulting in a pneumothorax,
       which is an abnormal air collection between the chest wall
       and the lung. This air collection can compress or collapse
       the lung.

    3) Escaped air can enter the pulmonary veins, from where it can
       travel to the arterial circulation as an air embolism
       (traveling air bubbles). This is by far the most serious
       complication of a ruptured lung, since the air embolism can
       block blood vessels to the brain or heart and be fatal.

> Second question: How fast after loss of preasure does this occur?

Essentially instantly. Again quoting Dr. Martin:

     The pressure difference across the lungs (from inside to outside)
     that is the threshold for experimental barotrauma is about 80 mm
     Hg; this can occur with a breath-hold ascent from only four feet!

Pop-erk-gasp-thud.

--
Doug Jones
Rocket Plumber, XCOR Aerospace
http://www.xcor-aerospace.com

From: Doug Jones <random@qnet.com>
Newsgroups: sci.space.tech
Subject: Re: Non-pressurized "pressure suit"?
Date: Mon, 27 Mar 2000 19:59:24 -0800

Michael J Wise wrote:
>
> Doug Jones wrote:
>
> > Essentially instantly.
> [snip]
> > Pop-erk-gasp-thud.
>
> So the 30 second figure is bogus?
> Exposure to hard vacuum kills instantly?

No- severe lung overpressure (gas in lungs, vacuum outside) causes
lethal lung *damage* instantly, but does not *kill* instantly (it's very
hard to kill a mammal in less than several tens of seconds unless the
brain is destroyed).  Conciousness would be lost in ten to fifteen
seconds as with any other vacuum exposure, but the victim would not be
revivable after being restored to pressure.

Hard vacuum can be suvived for around 30 to 60 seconds, with rescue and
emergency room treatment afterward- provided the lungs are emptied fast
enough to prevent air embolism.

--
Doug Jones
Rocket Plumber, XCOR Aerospace
http://www.xcor-aerospace.com

Newsgroups: sci.space.tech
From: henry@spsystems.net (Henry Spencer)
Subject: Re: Future space suits
Date: Thu, 8 Feb 2001 17:22:18 GMT

In article <95q969$abl$1@nnrp1.deja.com>,  <putaro@my-deja.com> wrote:
>> I think they'd get over it fast once they saw people wearing them in
>> vacuum chambers.
>
>So, I've seen the "skin suit" concept mentioned very often, especially
>in SF novels.  However, I have yet to see how the "tricky bits" of
>anatomy are going to be handled.  Specifically, the genitalia and
>anus.  Another pressurized hard area wrapped around the hips?

No, little shaped balloons inside the suit, to fill the space between the
simple convex suit shape and the complicated and sometimes concave body
shape.  The hips are not the only region where you need them, they show up
in places like the armpits too.

This is one of those areas where they made it sort of work, and it seemed
likely that satisfactory solutions were possible, but full engineering
development was never finished.

>...Have there been any
>serious treatments of the idea beyond "Oh yeah, if I wrap Spandex on my
>skin that will work"?

Fairly serious, during the short period when there was some R&D funding
for the idea.  Guys wore prototype suits in vacuum chambers.  There were
problems, but nothing disastrous.
--
When failure is not an option, success  |  Henry Spencer   henry@spsystems.net
can get expensive.   -- Peter Stibrany  |      (aka henry@zoo.toronto.edu)