TransHab as storm shelter

In article ,
Josh Gigantino wrote:
While building out a TransHab-type inflatable station module, fill one
of the outer layers with up to a meter depth of water. Even 20cm of
H2O should help for day-to-day radiation shielding. This should
provide a very good shelter against solar storms...

20cm or so of water is a good storm shelter for interplanetary space or
high orbit. (There's no point in having it in LEO, which is largely
shielded by the magnetosphere.)

However, you *don't* want it around your entire living quarters. For one
thing, it's very heavy. For another, even 1m of water is not enough to
stop heavy cosmic rays and all their secondary particles, which means you
quite possibly get a higher radiation dose that way than with no
shielding. Unless you can provide complete shielding -- which is probably
more like 10t/m^2 than 1t/m^2 -- you want just a compact "storm shelter"
area shielded.

...Several layers of water bladders could
provide a frozen outer layer and liquids closer to the users - both
more comfortable and warmer...

Uh, there's no reason why the outer layer would be frozen. In fact, it
would probably be difficult to arrange for it to stay frozen. Manned
modules generate a lot of heat. (Thermal insulation goes *outside* the
pressure shell, for several reasons including the fact that it helps
provide micrometeorite protection.)

...For use as a storm shelter, assuming the 1m average
shielding, would the hatches/ends need to be blocked off with more
shielding? Would bags of water covering the hatches be enough to block
the omni-directional solar storm particles?

You would want to block the openings of a storm shelter unless they were
bent enough that there was no line of sight from interior to exterior.

...Would equpiment
inside such a module be able to survive repeated passes (in a highly
eccentric orbit) through the Van Allen belts?

That's one environment where shielding along these lines might be useful,
although I can't quote numbers off the top of my head.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

(Henry Spencer) wrote in message ...
In article ,
Josh Gigantino wrote:
While building out a TransHab-type inflatable station module, fill one
of the outer layers with up to a meter depth of water. Even 20cm of
H2O should help for day-to-day radiation shielding. This should
provide a very good shelter against solar storms...

20cm or so of water is a good storm shelter for interplanetary space or
high orbit. (There's no point in having it in LEO, which is largely
shielded by the magnetosphere.)

20cm is enough for shelter from solar storms? Ideally, the same unit
could be filled with foam or water depending on application.

However, you *don't* want it around your entire living quarters. For one
thing, it's very heavy. For another, even 1m of water is not enough to
stop heavy cosmic rays and all their secondary particles, which means you
quite possibly get a higher radiation dose that way than with no
shielding. Unless you can provide complete shielding -- which is probably
more like 10t/m^2 than 1t/m^2 -- you want just a compact "storm shelter"
area shielded.

Just re-examined the Millenium Project- Savage's numbers agree with
yours, his suggestion being to make 5m thick water-filled walls (1/2
shielding of Earth's atmosphere). For cosmic rays (from your previous
posts on subject), they basically scatter into highly ionized pieces
that do more damage in tissue. Is there a way to shield against them?
Something like M2P2 or that rad-plastic in the space news lately?

For the H2O-filled Hab, the requirement would be for solar storms and
the Van Allen belts mostly. The facility would mostly be company
workers, not tourists, rad limits would be somewhat more relaxed. For
LEO, would you recommend a foam-only TransHab? What about the HEEO
orbit I mention, and flights to Mars/asteroids?

...Several layers of water bladders could
provide a frozen outer layer and liquids closer to the users - both
more comfortable and warmer...

Uh, there's no reason why the outer layer would be frozen. In fact, it
would probably be difficult to arrange for it to stay frozen. Manned
modules generate a lot of heat. (Thermal insulation goes *outside* the
pressure shell, for several reasons including the fact that it helps
provide micrometeorite protection.)

What kind of processes could utilize this heat? The ones that I think
of include heating user water (showers) and boiling waste water as
part of a heat exchanger. Waste heat and available water could be used
for humidity control.

Would the water (plus several layers of kevlar, bladders, etc) provide
enough meteorite/impact protection?

You would want to block the openings of a storm shelter unless they were
bent enough that there was no line of sight from interior to exterior.

Ok. For what I'm thinking, any storm shelter is going to be in a
manufactured tube of some kind. Anything bigger is likely to be inside
an asteroid or Giant Space Tree(tm).

...Would equpiment
inside such a module be able to survive repeated passes (in a highly
eccentric orbit) through the Van Allen belts?

That's one environment where shielding along these lines might be useful,
although I can't quote numbers off the top of my head.

I'm probably using the "water balloon" idea in the books i'm working
on - the main use of the shielded Hab is for a giant HEEO
fuel/assembly depot. It just seemed like a natural combination of
techs. People are always saying that the Van Allen belts are
life-threatening, it seems like a good way to provide protection.

Would the 20cm (or 50?) around equipment and personnel be enough? (I
know you don't have numbers handy, just ballpark) These modules would
be integrated as part of a tankfarm, their mass becomes part of their
profit. Pointing and maneuvering would be less of an issue, it would
be gravity-gradient stable.

Would it be correct that a HEEO application might be the only
reasonable use of this type of inflatable? Would it actually be more
dangerous than a foam-filled inflatable (cosmic ray damage) on a Mars
mission?

thanx,
Josh

Henry Spencer wrote:
You would want to block the openings of a storm shelter unless they
were bent enough that there was no line of sight from interior to
exterior.

Even if they were bent, wouldn't you still get lots of radiation via
Compton scattering?
--
Keith F. Lynch - http://keithlynch.net/
Please see http://keithlynch.net/email.html before emailing me.

A group of engineers including David Cavalieri were granted a patent
on this very idea a few years ago. That patent is owned by Bigelow
Aerospace. Anthony Zupperro had an idea for a PBO bag that would be a
nuclear powered steam rocket "ice ship" even earlier. The existence of
prior art and the previously mentioned problems, (That much water is
heavy and it won't stop all cosmic rays) is all true, making the value
of the patent very dubious indeed.

NASA had a very small storm shelter baselined inside the transhab for
use during the infrequent and unpredictable solar proton storms from
the sun for long duration missions like the 9 month chemical rocket
transit from earth to mars.

In article ,
Keith F. Lynch wrote:
You would want to block the openings of a storm shelter unless they
were bent enough that there was no line of sight from interior to
exterior.

Even if they were bent, wouldn't you still get lots of radiation via
Compton scattering?

My impression is that this isn't a big issue at the energies of interest,
but I could be wrong -- I haven't looked into the details.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

In article ,
Josh Gigantino wrote:
20cm or so of water is a good storm shelter for interplanetary space or
high orbit. (There's no point in having it in LEO...

20cm is enough for shelter from solar storms?

Probably, yes -- it depends a little bit on what assumptions you make and
how conservative you are.

...For cosmic rays (from your previous
posts on subject), they basically scatter into highly ionized pieces
that do more damage in tissue. Is there a way to shield against them?
Something like M2P2 or that rad-plastic in the space news lately?

Nothing that will stop them reliably in a short distance, I fear. The
energies are still pretty high and they're fairly penetrating.

For LEO, would you recommend a foam-only TransHab? What about the HEEO
orbit I mention, and flights to Mars/asteroids?

For LEO, it depends a little on which LEO you're in, but by and large you
don't need a lot of shielding. For an orbit passing through the belts
with any regularity, you'd need a bunch, but I don't have numbers on hand.
Out in deep space, you want either complete shielding (5-10t/m^2,
impossibly heavy for near-future vehicles) or else a small shielded storm
shelter and relatively little shielding on the rest.

Uh, there's no reason why the outer layer would be frozen. In fact, it
would probably be difficult to arrange for it to stay frozen. Manned
modules generate a lot of heat...

What kind of processes could utilize this heat?

There isn't really anything terribly practical, because it's at quite low
temperatures, which makes exploiting it fundamentally difficult. About
all you can do is get rid of it, and even that's a nuisance, since you
need quite a bit of radiator area. (That's what the inside surfaces of
the shuttle cargo-bay doors are, for example.)

...Waste heat and available water could be used for humidity control.

Humidity control in a manned spacecraft with a recirculating air system
generally means dehumidification, not humidification. Human bodies put
out substantial amounts of water vapor.

Would the water (plus several layers of kevlar, bladders, etc) provide
enough meteorite/impact protection?

The way to protect against micrometeorites (and in LEO, space debris) is
with multiple thin "bumper" shields spaced well out from the main hull.
It's helpful to add low-density material, e.g. thermal insulation, in the
gaps... but the #1 way to improve the protection is to make the gaps
*wider*. An incoming object hits the first shield and turns into an
expanding cloud of plasma and fragments, and the more time that cloud has
to expand before it reaches the next layer, the less chance that enough of
it will hit in one place to penetrate. Wider gaps are more effective than
more mass, and multiple thin walls are more effective than one thick wall.

...People are always saying that the Van Allen belts are
life-threatening, it seems like a good way to provide protection.
Would the 20cm (or 50?) around equipment and personnel be enough? (I
know you don't have numbers handy, just ballpark)

Gut feeling, 20cm isn't enough but 50cm might be.

Would it be correct that a HEEO application might be the only
reasonable use of this type of inflatable? Would it actually be more
dangerous than a foam-filled inflatable (cosmic ray damage) on a Mars
mission?

Right, you *don't* want to live inside 20cm of shielding in deep space,
because the cosmic-ray-secondary dose inside that sort of shield is
rather higher than the cosmic-ray-primary dose outside it. Only when
a giant solar flare temporarily changes the outside environment for the
worse do you retreat inside, and that fortunately is rare.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

In article ,
Tim McDaniel wrote:
The way to protect against micrometeorites (and in LEO, space debris)
is with multiple thin "bumper" shields spaced well out...

I take it that that doesn't work for cosmic rays -- enough shielding
far out to break up the cosmic ray particles, and distance from the
bumper shields to let time take care of the cosmic ray fragments?
That could only work if the fragments were almost all slow or almost
all very quick to decay.

Alas, cosmic rays are very energetic, and so many of the secondaries are
moving very fast and go a long way before decaying. The showers of
secondaries from cosmic rays being stopped in the upper atmosphere are
easily detected on the ground; in fact, the muon and the pion were both
first discovered as cosmic-ray secondaries. Also, some of the eventual
decay products would themselves remain dangerous, e.g. fragments of nuclei
might decay a little but wouldn't disappear.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

In article ,
John wrote:
Right, you *don't* want to live inside 20cm of shielding in deep space,
because the cosmic-ray-secondary dose inside that sort of shield is
rather higher than the cosmic-ray-primary dose outside it.

Would you even want to live *near* such a structure? Since the cosmic
rays come from all directions, won't many of them traverse both 20cm
walls and creating a shower of secondary particles radiating away from the
storm shelter?

Indeed they would. It would be *less* of an issue outside the shelter,
because only the cosmic rays coming from the far side of the shelter would
be an issue, whereas inside the shelter you're getting it from all sides.
But it would be preferable to locate the shelter away from normal sleeping
and working quarters.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

In article ,
Travis P wrote:
...center of the ship is the water storage tanks, but the tanks have
storage rooms in the centers that are surrounded by the water. When
needed, the entire crew can fit in there for days at a time.
Uncomfortable, but it's good dual use. One problem would be the
diminished quantity of water towards the end of the mission.

Fortunately, both food -- even dehydrated -- and human wastes have plenty
of water content, so you can use them for storm-shelter shielding.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

(Travis P) wrote:
[...]

Kim Stanley Robinson used this idea in his Mars trilogy. In the
center of the ship is the water storage tanks, but the tanks have
storage rooms in the centers that are surrounded by the water. When
needed, the entire crew can fit in there for days at a time.

Well, I wouldn't swear that Robert Heinlein used the water tanks, but
the idea of a storm shelter had been figured out by the time he wrote
Podkayne of Mars, which was originally published in 1963. There was
more detail about being inside the shelter than on how the shelter was
built, but it sounds like the idea was well worked out back then.

/dps