Minimal space-suit

In article ,
Tom Burke wrote:
I think you're all missing an important point... HEAT...
I suppose you could cover your suit with a couple of layers of MLI,
though - but that stuff's pretty fragile, & you'd be quick to
overheat in it, because it's too good of an insulator while in a
vacuum (something like 99.5% efficient)

The orthodox answer to this for skinsuits is that you put an insulation
layer (not necessarily MLI), with vents, outside the suit itself. Since
it isn't airtight, it can be just clothes you put on, fastened with
zippers or buttons -- think of ski pants and parka. That evens out
extremes and blocks raw sunlight, leaving you with a need to get rid of
metabolic heat, which you do the same way you do on Earth: by sweating
into vacuum, straight through the suit.

That also provides some level of micrometeorite protection, which is
desirable.
--
MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer
first ground-station pass 1651, all nominal! |

In article ,
stmx3 wrote:
...I believe NASA has studied MCP gloves in the past
because of the advanced dexterity they provide. But I wonder how they
fare in the +/- 250 deg F in space or if they'll be usefull in on-orbit
construction, since touch temps. are so drastic.

Non-airtight insulating overgloves are a trivial solution. Standard
industrial gloves would probably work, although NASA would doubtless
want a custom design.
--
MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer
first ground-station pass 1651, all nominal! |

I think this thread could get better if it focussed on a minimal
requirement that the person be able to do survival work for at least
30 min once she finds herself in a space environment. If you are in a
real jam in space, far from anywhere, I don't see much payoff in
sitting there breathing and waiting for things to just get better.

Seems to me, some sort of a quick-donnable elastic outfit with a shell
around the chest region and in front of the face is needed for this.
The space in the chest shell maintains constant volume for breathing
-- gas moves between the lungs inside and the outside as the rib
structure opens and closes. So the wearer doesn't need to attend to
fighting for breath. And the face shell provides for vision and a gas
pathway for breathing.

Another idea is a sausage-shaped beachball suit with arms. You climb
in, get your arms into the suit's arms, zip it, and hit the
environment switch.

Cheers -- Martha Adams

(Henry Spencer) wrote:

In article ,
stmx3 wrote:
...I believe NASA has studied MCP gloves in the past
because of the advanced dexterity they provide. But I wonder how they
fare in the +/- 250 deg F in space or if they'll be usefull in on-orbit
construction, since touch temps. are so drastic.

Non-airtight insulating overgloves are a trivial solution. Standard
industrial gloves would probably work, although NASA would doubtless
want a custom design.

Only if NASA is unwilling to accept the extreme loss of dexterity that
such gloves commonly cause.

D.
--
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Corrections, comments, and additions should be
e-mailed to , as well as posted to
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discussion.

Ian Stirling wrote in message ...
snip
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.
snip

One problem skin suits that I've never seen discussed:
Assuming 7psi air pressure in the helmet and a 10 inch diameter
opening, there would be 550 pounds of force pushing the helmet
upwards. A pressurized suit would balance that force, carrying the
load over much of the outwardly-stretched non-permeable layers. But a
non-pressurized skin suit would tend to concentrate that force through
a groin-circling harness, would it not? Imagine doing a 8 hour EVA
wearing the equivalent of a parachute harness while under 3 gees
acceleration. Ice pack, please!

On this interesting topic, I noticed a relevant bit on public TV last
weekend. It concerned the Russian space effort, and the first man
(Russian) to "walk in space."

Apparently, to exit his space capsule, he had to transit a rather
narrow tunnel. He got out OK; but then came return time, he couldn't
make it. He finally did, by the expedient of "depressurizing his
space suit." (That is *definitely* the description used.) To me,
this implies time spent to 1) depressurize; 2) get through the
tunnel; 3) do a finely balanced operation of pressurizing the airlock
or capsule while opening the space suit to let the air in.

Maybe someone else was with him to choreograph the process, but that
wasn't defined in the piece I saw.

If someone could find authoritative word about this, I think it would
contribute to the discussion here.

Cheers -- Martha Adams

In article , Martha H Adams wrote:

Apparently, to exit his space capsule, he had to transit a rather
narrow tunnel. He got out OK; but then came return time, he couldn't
make it. He finally did, by the expedient of "depressurizing his
space suit." (That is *definitely* the description used.) To me,
this implies time spent to 1) depressurize; 2) get through the
tunnel; 3) do a finely balanced operation of pressurizing the airlock
or capsule while opening the space suit to let the air in.

Maybe someone else was with him to choreograph the process, but that
wasn't defined in the piece I saw.

He had a partner (Belyayev), but he was inside the spacecraft at the
time.

What happened, AIUI, was that Leonov had trouble fitting inside the
airlock due to the stiffness of the suit (thought experiment - a rubbery
baloon will pass through a slightly smaller hoop easily, a basketball
won't). After, no doubt, a modicum of panic and a selection of
interesting Russian epithets, he decided to bleed some air from the suit
to try and reduce the stiffness - not completely depressurising, but
partly; in the analogy above, think of deflating the basketball a bit.

(I haven't had a chance to examine the suit; I expect there was a manual
bleed valve or the like somewhere he could get at; to the best of my
knowledge, Voshkod worked at 1atm, so I believe his suit also did, and
working at 0.7atm was commonly used in the US - so it's not a
significant physiological hazard.)

Having scrambled back in, the hatch wouldn't seal properly, and the
cabin got flooded with oxygen; there wasn't automatically a "finely
balanced operation" there ;-)

The mission wen't downhill after this, too; the retrorockets failed, so
they used the backups, then the service module failed to separate and
they almost burned up. They proceeded to land in the middle of the
Urals, even further from anywhere than normal, and got to spend the
night in a freezing forest surrounded by wolves, before help arrived.

--
-Andrew Gray

Bill Bogen wrote:
Ian Stirling wrote in message ...
snip
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.
snip

One problem skin suits that I've never seen discussed:
Assuming 7psi air pressure in the helmet and a 10 inch diameter
opening, there would be 550 pounds of force pushing the helmet
upwards. A pressurized suit would balance that force, carrying the
load over much of the outwardly-stretched non-permeable layers. But a
non-pressurized skin suit would tend to concentrate that force through
a groin-circling harness, would it not? Imagine doing a 8 hour EVA
wearing the equivalent of a parachute harness while under 3 gees
acceleration. Ice pack, please!

It's a bit tricky to get the balance between keeping inward
pressure constant over the whole skin, and not pinching bits.
This is trivial for spherical astronauts.

However, looking at the outline of the body from the top and bottom, the
total areas match.

Consider a naked human in 0G and 14PSI.
Cover them with a rigid surface with a helmet at one end.
Now, exposure to vacuum won't change the internal pressure.

The trick in a skinsuit is to copy the internal stresses produced by this
rigid surface with a flexible one that lets the astronaut move around.

If done right, there is no problem.
However, this is rather tricky.

--
http://inquisitor.i.am/ | | Ian Stirling.
---------------------------+-------------------------+--------------------------
"The theory of everything falls out trivially." -- Etherman, sci.physics kook.

In article ,
MSu1049321 wrote:
I think painted on skinsuits, or pressure garment skinsuits made of a
thermally- set shrinking material, will eventually be the way to go over
something zippered. One size WOULD then fit all accurately. Too, such suits
might offer quite a savings in storage space over prefab traditional suits.
You'd go out in a fresh one every time, except for reusable parts of the PLSS,
the helmet, connectors, etc.

However, they'd have the same downside as other expendable devices:
because you get a fresh one each time, there is no way to *test* the
hardware that you are betting your life on. This is a big problem unless
rigorous quality control can reliably ensure very consistent behavior.
--
MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer
first ground-station pass 1651, all nominal! |