Here's some stuff about storm shelters.

"When the sun flares, it produces x-rays, gamma-rays, and energetic
particles. The energetic particles are the worst, but they are
delayed compared to the X-rays and gamma-rays, so you have some
warning that they are coming. This gives you time to get into
a 'storm shelter', a well-shielded area that you can live in for a
few days until the particles die down. A good place for a storm
shelter would be in the center of the ship, surrounded by the water
tanks. If you don't have a storm shelter (e.g. if you are out
moonwalking in just your suit) a bad solar flare can kill you by
radiation sickness.

http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980119b.html

"...most SPEs (Solar Particle Events) are relatively short-lived
(less than 1-2 days), which allows for relatively small volume "storm
shelters" to be feasible. To minimize exposure, the crew would be
restricted to the storm shelter during the most intense portion of
the SPE, which may last for several hours. Storm shelters with
shielding of approximately with 20 g/cm2 or more of water equivalent
material will provide sufficient shielding to protect the crew. "

http://srag-nt.jsc.nasa.gov/docs/TM104782/techmemo.htm

====================
Now, with a storm shelter, you can afford to have less overall mass.

Besides increased mobility (if anyone ever wants to go there),
there's also the lower cost and ease of construction. Less weight to
lug around (or less pasting) means faster, and less laborious,
construction. Less material means less slag to cart around or bundle
up which also means faster, as well as more energy-efficient,
construction.

It's not just what works.

Walking works.

Riding a horse works.

If you can get there sitting on your butt, then why the hell walk?

George
http://cygo.com/

From: George Perkins [mailto:spacework@...]

Here's some stuff about storm shelters.

And it's fine, if we're talking about missions to Mars type situations
(which is where I'd guess this material comes from). My only problem was
that I can't see a diverse population of 10,000 or more living this way. If
the mobile habitats you're envisioning have populations much smaller than
that, composed of well-trained, alert, young adults, and with no birds or
wildlife in the ecology (or large animals in the agriculture), then we're
not really disagreeing, we're just discussing different topics.

O'Neill talked about a storm shelter in a proposed small spacecraft for
transporting a family to the Belt. I remember him commenting on the shelter
doubling as the nursery. The weight savings of a thinner outer shield made
this an advantageous approach. But here we're talking about a small crew
composed of one or maybe two nuclear families, all within a few tens of feet
of the shelter at all times.

Besides increased mobility (if anyone ever wants to go there),

An undeniable benefit. And I can see great usefulness in a mobile habitat.

there's also the lower cost and ease of construction.

We might well argue that the material costs are zero, since a slag shield
would use material which we would produce in any case. If we had no use for
it, I supposed there'd be certain cost associated with its proper disposal.
Construction would probably be along the lines of building a brick wall with
50-foot wide bricks. Since all the components would be identical, in
endlessly repeating patterns, this should lend itself well to automation.

The most demanding aspect of the contruction will be in creating a pressure
vessel with no leaks. The radiation shield won't require nearly the
precision.

Some people promote active shielding, which involves a powerful positive
charge on the hull, and a powerful magnetic field for deflecting the
lower-mass electrons. The engineering difficulties involved caused the
Ames-Stanford team to abandon that approach in favor of 6-foot thick passive
shielding. But if we want to instead talk about a mobile habitat, I
certainly think the savings in thrust needed for a given delta-V might make
a stronger case for active.

Regards,

Mike Combs

From:
George Perkins [mailto:spacework@...]
Here's some stuff about storm shelters.

And it's fine, if we're talking about missions to Mars type situations (which is where I'd guess this material comes from). My only problem was that I can't see a diverse population of 10,000 or more living this way. If the mobile habitats you're envisioning have populations much smaller than that, composed of well-trained, alert, young adults, and with no birds or wildlife in the ecology (or large animals in the agriculture), then we're not really disagreeing, we're just discussing different topics.

O'Neill talked about a storm shelter in a proposed small spacecraft for transporting a family to the Belt. I remember him commenting on the shelter doubling as the nursery. The weight savings of a thinner outer shield made this an advantageous approach. But here we're talking about a small crew composed of one or maybe two nuclear families, all within a few tens of feet of the shelter at all times.
Besides increased mobility (if anyone ever wants to go there),

An undeniable benefit. And I can see great usefulness in a mobile habitat.
there's also the lower cost and ease of construction.

We might well argue that the material costs are zero, since a slag shield would use material which we would produce in any case. If we had no use for it, I supposed there'd be certain cost associated with its proper disposal. Construction would probably be along the lines of building a brick wall with 50-foot wide bricks. Since all the components would be identical, in endlessly repeating patterns, this should lend itself well to automation.

The most demanding aspect of the contruction will be in creating a pressure vessel with no leaks. The radiation shield won't require nearly the precision.

Some people promote active shielding, which involves a powerful positive charge on the hull, and a powerful magnetic field for deflecting the lower-mass electrons. The engineering difficulties involved caused the Ames-Stanford team to abandon that approach in favor of 6-foot thick passive shielding. But if we want to instead talk about a mobile habitat, I certainly think the savings in thrust needed for a given delta-V might make a stronger case for active.

Regards,
Mike Combs

George Perkins wrote:

> Here's some stuff about storm shelters.
>
> "When the sun flares, it produces x-rays, gamma-rays, and energetic
> particles. The energetic particles are the worst, but they are
> delayed compared to the X-rays and gamma-rays, so you have some
> warning that they are coming. This gives you time to get into
> a 'storm shelter', a well-shielded area that you can live in for a
> few days until the particles die down. A good place for a storm
> shelter would be in the center of the ship, surrounded by the water
> tanks.

Or the low-g, cylindrical swimming pool. Much more fun.

> If you don't have a storm shelter (e.g. if you are out
> moonwalking in just your suit) a bad solar flare can kill you by
> radiation sickness.
>
> http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980119b.html
>
> "...most SPEs (Solar Particle Events) are relatively short-lived
> (less than 1-2 days), which allows for relatively small volume "storm
> shelters" to be feasible. To minimize exposure, the crew would be
> restricted to the storm shelter during the most intense portion of
> the SPE, which may last for several hours. Storm shelters with
> shielding of approximately with 20 g/cm2 or more of water equivalent
> material will provide sufficient shielding to protect the crew. "
>
> http://srag-nt.jsc.nasa.gov/docs/TM104782/techmemo.htm
>
> ====================>
> Now, with a storm shelter, you can afford to have less overall mass.
>
> Besides increased mobility (if anyone ever wants to go there),
> there's also the lower cost and ease of construction. Less weight to
> lug around (or less pasting) means faster, and less laborious,
> construction. Less material means less slag to cart around or bundle
> up which also means faster, as well as more energy-efficient,
> construction.
>
> It's not just what works.
>
> Walking works.
>
> Riding a horse works.
>
> If you can get there sitting on your butt, then why the hell walk?
>
> George
> http://cygo.com/
>
> Make good on the promise you made at graduation to keep
> high school alumni--chances are you'll find your friends!
>

Al Globus
aglobus@..., (650) 604-4404
http://www.nas.nasa.gov/~globus/home.html

The dinosaurs weren't spacefaring. We are. I don't think that's an accident.
Maybe we are life's taxi to the stars.

I think we should:

1. Devote half of NASA's budget ($7 billion) to reaching NASA's 2020 goal of
reducing launch costs to Low-Earth-Orbit to $220/kg with a 0.01% failure
rate.
This should enable space tourism. The resulting orbital hotels will need to
develop efficient orbital life support and other necessary technologies.

2. Build orbital space colonies. The materials in the largest asteroid are
sufficient for orbital colonies with a combined surface area about 500 times
greater than Earth's. Eros alone could make over ten thousand space colonies,

each with about about 10 square kilometers of 1g living area.

3. After a few generations of orbital living, people won't need their colony
to be near Sol. Then small groups of colonies with populations in the
tens-of-thousands can set out on multi-decade journeys to nearby stars.

Except the launch goals, none of this is even a little bit official.