h a l f b a k e r yQuis custodiet the custard?
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So, I was thinking about spacesuits.
At the moment, there are two design options for spacesuits.
One is the mostly-fabric design that astronauts actually use.
It
is very sophisticated, but it is still exhausting to work in,
because the internal pressure tends to inflate to suit into a
particular posture, and any movement has to overcome that
force.
The other is the "lobster" type of suit (more familiar as a
deep-
sea suit). It consists of rigid sections articulated at various
points. It's designed such that its internal volume stays the
same in all positions, which means that air pressure does not
resist movement at all. It's said to be much less tiring to
work
in. However, it has some limitations imposed by the nature
of
the joints (which must all be airtight, of course). As a
result,
some movements must be made in the right order (eg, first
move the shoulder, then the elbow; not the other way
around)
or the suit "jams". It's also difficult to maintain good seals at
all the joints.
A third type of suit has been proposed in the past, consisting
of nothing more than a body-hugging mesh (except for the
head, which is sealed into a regular helmet). Skin can cope
quite well with vacuum as long as it is confined by a fairly
fine
mesh. The mesh has to provide a supporting force of only a
very few PSI. These "stocking suits" would be great, except
that they
don't work. The reason they don't work is that you can't
make
a mesh suit which presses evenly on all areas of skin, in all
body positions.
So, here are two possible ways to implement the mesh
spacesuit.
Way 1: glue-on mesh. The astronaut dons what is basically a
mesh leotard, and is then liberally sprayed with a flexible
glue
that bonds the mesh to the skin. Once glued in place, the
mesh will serve its compressive function regardless of
movements. The mesh suit can be removed by spraying with
a
suitable agent to break the mesh/skin bond. There are
plenty
of biological-based glues (for instance, the ones that mussels
use to glue their attachment threads to rocks) that will
serve
admirably and can be dissolved by fairly benign enzyme
solutions.
Way 2: thermally-responsive mesh. For this, we need the
mesh to be made of a bimetallic thread, oriented in the
right
way. If he/she moves in such a way as to create a gap
between body and mesh, the cooling of the body-side of the
mesh filaments will cause them to bend, until they once
again
contact the body. If the filaments of the mesh are fine
enough, this response could easily keep pace with
movements.
(*And yes, fishnet would be much too coarse and bits of you
would bulge out between the fibres.)
A song has been written about this idea ...
https://www.youtube...watch?v=zPwMdZOlPo8
[normzone, Aug 08 2019]
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Unfortunately, skin is elastic, so "glue-on" won't be
particularly good if you want to move & breathe & so
forth.
Thermal could work; I'm not sure it would respond fast
enough (or physically change enough) to the small
changes in temperature.
Way 3 is to use an "active" tension suit: pressure sensors
against the skin instruct nitinol / piezo / actuator /
something to maintain a particular pressure by
continuously adjusting the tension.
Complications (in all options) come in places of "negative
curvature", such as armpits, groin, front-of-ankle. A small
"active" bladder (specifically shaped to fit) in those places
could keep pressure while allowing movement. And of
course, breathing needs to be accommodated; unless a 2-
way-pumped air supply both fills AND empties the lungs,
without the need for chest/diaphragm movement.
(Yes, I have put quite a bit of thought in to tension suit
design before...) |
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//"glue-on" won't be particularly good if you want to move &
breathe & so forth// Depends on the stretchiness of the
fibres, at least for moving and breathing. If you want to get
up to so forth, it's probably safer for everyone if you do it
inside the space ship. |
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<Contemplates mental image of bits of [MB] bulging out between the fibres/> |
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<Considers mental image of [MB]'s siblings in similar circumstances /> |
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Interesting - so why wouldn't a neoprene scuba wetsuit (with water providing a thin layer between the body and the suit, and filling in any voids) together with a proper helmet work as a spacesuit? |
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Because you'd end up with a human-shaped balloon - the suit
would resist any movement that reduced its volume, just as
the current suits do. |
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Yes, so the astronaut might die from being unable to exhale |
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//bits of you would bulge out between the fibres. |
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<Frankie Howard>Oh no missus</FH> |
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How often do astronauts need to go outside? Seems a damn cheek when NASA spent oodles of tax payers cash making a nice capsule for them. |
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^Or accompanying regolith sampling stilettos? for that real 'time warp' capability. |
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