Space station future adrift (Soyuz purchase crisis)

In article ,
Rand Simberg wrote:
The best solution to the problem would be a mobile, high-pressure
suit, but NASA's never developed one.

While that's a possible solution to the spacewalk prebreathing problem, it
probably isn't enough to make spacesuit-based lifeboat/bailout methods
work. Such a suit is likely to be large and heavy -- the "hardsuit"
concepts are particularly massive -- meaning that you wouldn't have half a
dozen in each airlock. Moreover, getting into one is likely to be a slow
process, as for the current suits. A quick-donning, one-size-fits-all,
lightweight emergency suit is most unlikely to be a high-pressure suit,
at least not any time soon.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

In article ,
h (Rand Simberg) wrote:

The best solution to the [bends] would be a mobile, high-pressure
suit, but NASA's never developed one.

I've been thinking a lot about space suits lately. I'm starting to
wonder if they're not a good approach for orbital EVA-type work.

Has anyone considered instead a small mobile pod instead? I'm picturing
a hard shell slightly larger than a man, which the pilot/user
flies/wears around for assembly, maintenance, and perhaps even
sight-seeing tasks. It would have jointed arms & hands which the user
can stick his hands into to manipulate things, but when he doesn't need
to do that, he can withdraw his arms into the pod.

Possible advantages:

1. It could easily be made to withstand high internal pressure, so no
prebreathing is needed.

2. The user has a bit more freedom and comfort -- when you get an itch,
pretty much anywhere, you can scratch it, and internal controls (such as
for flying the thing, dispensing food/water, or taking a leak) can be
easily operated.

3. Probably less failure-prone, not that a spacesuit has ever failed as
far as I'm aware.

Disadvantages:

1. If you really need your legs for something, you're pretty much SOL --
I don't know how often this actually comes up on orbit.

2. If operated at a higher pressure, you still have the stiff-glove
problem that plagues other space suits.

One possible solution for #2 would be to have a pair of robotic waldoes,
perhaps on the other side of the pod, which can be used for some tasks
in place of gloves. But then, if the task could be done from a pod with
waldoes, it could probably be done via teleoperation.

But maybe we call that an advantage -- these pods could be operated
either by a wearer/pilot, or a remote pilot.

Anyway, this is off the top of my head, but it seems worth exploring,
don't you think? Any reactions?

Best,
- Joe

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On Tue, 30 Nov 2004 10:36:12 -0600, in a place far, far away, Earl
Colby Pottinger made the phosphor on my monitor
glow in such a way as to indicate that:

Why does prebreath take so long? Bubbles? But at the lower pressure tere is
not that much gas in the blood, is there? People often dive to 30 to 50 feet
and come back up in time measured in minutes not hours. So why so long?

Because it's a sudden pressure drop. It takes time to get the
nitrogen level down sufficiently to prevent the bends going from 10.2
to 4.3.

And
if caution is the main reason for such a long time how much can it be cut
back for an emergency?

Not much, unless life is threatened more than the bends.

The best solution to the problem would be a mobile, high-pressure
suit, but NASA's never developed one.

In article ,
Joe Strout wrote:
Has anyone considered instead a small mobile pod instead? I'm picturing
a hard shell slightly larger than a man, which the pilot/user
flies/wears around for assembly, maintenance, and perhaps even
sight-seeing tasks. It would have jointed arms & hands which the user
can stick his hands into to manipulate things, but when he doesn't need
to do that, he can withdraw his arms into the pod.

As Rand says, this is a very old idea. Unfortunately, it turns out that
legs are really quite useful in free fall, for holding you in place and
maneuvering you around (using foot restraints, of course). The pod
concepts mostly date from a time when people thought that working while
floating free would be easy, when in fact it's extremely difficult.

The idea is not ridiculous, but it's by no means obviously attractive.

1. It could easily be made to withstand high internal pressure, so no
prebreathing is needed.

Unfortunately, the place where high pressure bites worst is in the arms
and especially the gloves. Doing something else for the torso and legs
isn't that much of a win.

2. The user has a bit more freedom and comfort -- when you get an itch,
pretty much anywhere, you can scratch it, and internal controls (such as
for flying the thing, dispensing food/water, or taking a leak) can be
easily operated.

Some of the smaller astronauts can pull an arm into the shuttle suits to
scratch an itch. Just barely.

There have been a number of proposals for suits with a bit more room in
the torso, and other small changes, specifically to permit controls,
displays, and services inside. There are advantages and disadvantages.

3. Probably less failure-prone, not that a spacesuit has ever failed as
far as I'm aware.

There have been no serious failures in space, but the minor problems that
have happened have mostly been in arms and gloves.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

In sci.space.policy Ian Stirling wrote:
In sci.space.policy Henry Spencer wrote:
In article ,
Phil Paisley wrote:
Do I hear a MOOSE coming over the horizon?
Seriously, isn't it about time someone gave some serious thought to an
ultra-minimal personal re-entry scheme?

Alas for the notion, that's not really what's called for. A lifeboat that
can carry at least two or three people is generally superior, not least
because it doesn't require donning a spacesuit on short notice (which is
all too likely to cause decompression sickness, aka the bends -- not only
painful but also deadly dangerous).

And putting on my heretic hat...
Does a minimal reentry scheme require a spacesuit?
If there is a hole in your reentry vehicle, you'r probably already dead.


IMHO it goes (or should go) like:
life support in the suit - need suit
life support in the capsule - don't need

are the halfways really all that useful?


--
Sander

+++ Out of cheese error +++

On Tue, 30 Nov 2004 12:58:38 -0600, in a place far, far away, Joe
Strout made the phosphor on my monitor glow in such a
way as to indicate that:

The best solution to the [bends] would be a mobile, high-pressure
suit, but NASA's never developed one.

I've been thinking a lot about space suits lately. I'm starting to
wonder if they're not a good approach for orbital EVA-type work.

Has anyone considered instead a small mobile pod instead?

That's actually an idea as old as the space age itself. There used to
be a mural in the DEI Room at Rockwell Downey showing assembly workers
with them putting together a solar power satellite.

But NASA hadn't developed one of those, either.

"Joe Strout" wrote in message
...
In article

Has anyone considered instead a small mobile pod
instead? I'm picturing a hard shell slightly larger than a
man, which the pilot/user flies/wears around for assembly,
maintenance, and perhaps even sight-seeing tasks. It
would have jointed arms & hands which the user can
stick his hands into to manipulate things, but when he
doesn't need to do that, he can withdraw his arms into the
pod.

I have had similar thoughts, somewhere in the archives. This approach
strikes me as far easier and more effective than a suit.

It might also be directly docked to the habitat, perhaps avoiding the
need for an airlock.

The mass can actually be similar to that of a suit, it might even be
inflatable like Transhab, if packing volume was a real issue.

One of the things I really like about it is that it can be modular and
one size fits all. You could easily upgrade adding extra capabilities,
endurance, power, propulsion, extra inflatable volumes for passengers,
etc. It could serve as the basis for a truly multi role and even
emergency escape and rescue vehicle.

In an emergency situation it should give you the ability to do
something, retrieve stores, build stuff from the wreckage, etc. Options
would be greatly increased. I suppose it might even grab a heat shield
and parachute and return to earth. :-)

However I do not see anyone working on such things, so something is
wrong with it somewhere.

Pete.

Henry Spencer wrote:
When people talk about an "ultra-minimal personal re-entry scheme", they
usually mean something that doesn't even have an outer hull, just a
spacesuit and some sort of heatshield.

Nop. I have always though of something the size of a phone booth. Perhaps
teardrop shaped.

One option not mentioned is that of having the rewmember egress from the
escape pod at the right altitude and deploy a parachute for landing. This
would greatly simplify the escape pod by not requiring it to survive the landing.

Of course, of the escape pod must act as a cadillac ambulance, capable of
carrying someone and landing him/her safely without a bump, then the above may
not be applicable. But developping proper medical capability in orbit would
remove the need for "cadillac ambulance" service, and relagate espace pods to
only returning to earth after massive station failure.

Joe Strout wrote:
a hard shell slightly larger than a man, which the pilot/user
flies/wears around for assembly, maintenance, and perhaps even
sight-seeing tasks. It would have jointed arms & hands which the user
can stick his hands into to manipulate things, but when he doesn't need
to do that, he can withdraw his arms into the pod.


That is what the candarm is for and will be able to do once it gets its
"hand". Getting PGDF grapple points on the russian segment would be the smart
thing to do since the arm would then be able to service all of the station.
The hand is designed to have enough dexterity to change computer boards
outside of the station.

Note that NASA is developping such a unmanned pod to save Hubble from the
presidential decree that the Shuttle is no longer able to do what it was
supposed to do. (go to hubble and repair/improve it).

Henry Spencer wrote:
[...]
[...] A quick-donning, one-size-fits-all,
lightweight emergency suit is most unlikely to be a high-pressure suit,
at least not any time soon.

Are the "skin suit" designs a candidate for this? Perhaps with a
high-pressure helmet?

IIRC, previous discussions pointed out that "skin suits" hadn't completely
solved the joint problem yet, but limited mobility might be acceptable in
an emergency exit, as long as you had enough to be able to pull yourself
along.

The other issue, for Quick Donning, is how to get in fast and still be
able to seal it; something more than an O'Niell wetsuit zipper would seem
to be needed.

Guess it is time to google on "skin suit" again...

/dps

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