I got my information from Dyffed Neal Dyar's web page. I asked him
where he got his information and this is what he sent me back.

<did,
however, specify composition, glass quartz, and basic "prism" design.
One design element is usually lost in the artistic license of every
illustration I've ever seen, which always show a clear view through
the
windows. In fact, the windows were intended to have a baffle or
louver,
so light incoming to the windows is refracted through a set of 45-
angle
mirrors, shield against cosmic radiation.

| | | | |
/ / / / /
| | | | |

This way, visible light passes through into the interior, but not
energetic particles or ionizing radiation. A simulation of a blue sky
is visible in daytime, but the solar disc would not, unless this was
simulated, too. The same would be true of the night sky, which would
also be starless.

Of course, a layer of clouds would block both the day and night sky
most
of the time. Actually, there would be two layers of cloud cover,
since
a circular or helical band of clouds would be halfway between the hull
and the axis, and you'd have look through a convex and a concave layer
to get the skylight directly above.

Z

>>

But I for one have found the idea of storing water over the windows
would serve as a radiation modifier, and would probably produce
more "natural" weather patterns inside the colony.

From: tomexe [mailto:tomexe@...]

I got my information from Dyffed Neal Dyar's web page. I asked him
where he got his information and this is what he sent me back.

<

Thanks. Now I know I didn't just miss it somehow.

But I for one have found the idea of storing water over the windows
would serve as a radiation modifier, and would probably produce
more "natural" weather patterns inside the colony.

Perhaps, but if at a high-orbital construction site, between 1 million tons
of water, and one million tons of slag, I know which is going to cost more.

Regards,

Mike Combs

From:
tomexe [mailto:tomexe@...]
I got my information from Dyffed Neal Dyar's web page. I asked him
where he got his information and this is what he sent me back.
<

Thanks. Now I know I didn't just miss it somehow.
But I for one have found the idea of storing water over the windows
would serve as a radiation modifier, and would probably produce
more "natural" weather patterns inside the colony.
Perhaps, but if at a high-orbital construction site, between 1 million tons of water, and one million tons of slag, I know which is going to cost more.
Regards,
Mike Combs

--- In spacesettlers@y..., "Combs, Mike" wrote:
> From: tomexe [mailto:tomexe@a...]
>

>
> But I for one have found the idea of storing water over the windows
> would serve as a radiation modifier, and would probably produce
> more "natural" weather patterns inside the colony.
>
> Perhaps, but if at a high-orbital construction site, between 1
million tons
> of water, and one million tons of slag, I know which is going to
cost more.
>
> Regards,
>
> Mike Combs

Well here is the thing. I have been visiting this website
http://silver.neep.wisc.edu/~neep533/neep533.html at the
University of Wisconsin for information about space construction. I
frequently refer to the lectures of 17 Feb, and 15,17,19 March. Its
three years old now, but it still seems to be a good site. At least I
havent found a better one yet in scouring the internet.

Acording to this, given the availability of enough electricity, to
produce heat, water is not hard to come by on the moon. It can be
acqured from the lunar soil.

Slag may be what the solid areas of the colony are made out of. This
same design that has 40 foot thick glass windows also has 50ft of
mooncrete or or slag bricks or both, making up the structure of the
solid panels and end caps. The actual thickness is actually more than
50 feet because of access tunnels, but any partical trying to get in
would have to pass through 50 feet of materaial-before coming into
contact with the landscaped topsoil yet. While particles trying to
get in on the windows would have to pass through 40 feet of glass and
4 miles of atmosphere to get to a person on the surface even without
water over the windows. Also the glass can be made denser than just
pure silicon. Leaded crystal, which mixes a couple percent of
powdered lead with the sand, also has good light transmission
qualities and would be denser.

Water may be more expensive to gather in the short run, but it is
reuseable, and has a lot of other functions than being a radiation
blanket. It can be used to transport heat energy through the colony,
from the sunward endcap and the cylinders in the factory ring, back
to the cold endcap, moderating temperatures and also creating a
current which could be tapped to provide even more electricity. Using
the mirrors as resevours would also humidify the atmosphere inside,
producing clouds and rain, a more natural habitat for the people,
plants and animals inside. The free water vapor would serve to
thicken the atmosphere inside and act as a further barrier to
radiation.

If you go to this page:
http://silver.neep.wisc.edu/~neep533/LEC16/0slide.html the last
half dozen slides (47-53) have charts that explain the amount of
cosmic background radiation exposure that a astronaut recieves on
three different missions, one to a space station, one to the moon,
and one to Mars, in a "standard" spacraft hull of 2g/cm2 Aluminum
alloy. It does not allow for solar flare events. Compare this with
the shielding provided by such large thicknesses of concrete and
glass. I think that for a Island 3 type colony only the endcap that
faced the sun all the time would require solar flare sheilding, the
rest of the colony would be in the shadow of that shield, and would
need only sheilding for cosmic background radiation.

The problem with relying on "appeal to authority" type arguments is
that there is no independent verification of results. While I admire
the work that Dyffed Neal Dyar did on his web page, I think it is
troubling to be relying on the physics underlying a sci-fi site.

Let's look at a few numbers to try to come to a better understanding
of the thicknesses involved in the pressure shell and the windows.

The 50 feet of mooncrete and 40 feet of windows don't ring true for
me. When I consider the thickness of radiation shielding for a
nuclear power plant and compare it to the above thicknesses, I'm led
to believe that something is askew.

Also, the mass involved is staggering. Consider:

4*pi*r2 is surface area of sphere.
2*pi*r*L is surface area of a cylinder

r = 2 miles * 5,280 feet = 10,560 feet
L = 20 miles * 5,280 feet = 105,600 feet

Two endcaps = 1,401,885,257 ft2
Cylinder = 7,009,426,286 ft2

The endcaps have no window area so they are 50 ft thick, thus there
is 70,094,262,860 ft3 of material.

The cylinder is half window and half shell, therefore

3,504,713,143 ft2 * 40 = 140,188,525,700 ft3 of glass
3,504,713,143 ft2 * 50 = 175,235,657,100 ft3 of slag.

Altogether, that is a volume of material, just for the shell not
including any buildings or support structure insided the habitat nor
exterior mirrors and farming modules, of 385,518,445,086 ft3 of
material.

If we assign a mass of 173.9 lbs/ft3 (lunar regolith) to that volume
we end up with a mass of 33,523,343,040 tons.

If we assume that this material must be launched from the surface of
the moon over a period of 20 years, then we're launching 53.1509
tons per second, every second for that 20 years.

Considering that 1 ft3 of lunar regolith takes 374 MW of energy to
propel up to the 3000 m/sec escape velocity, the power required to
launch that 53 tons per second will have to be 228.6 GW.

That power has to be a good portion of what is available on the
earth right now!!

ALso, if the payload size from the mass launcher is no smaller than
1 ft3, then we'll have to have 611 mass launchers firing once a
second with no downtime at all for 20 years.

For me to buy into the 50 ft/ 40 ft scenario, I'd have to be
convinced why a habitat would need more shielding that a nuclear
power plant, and even if I was convinced on that point, I'd then
have to conclude that an Island 3 would never be built. EVER.
Because the economics just wouldn't work based on the scale of
operation I've just outlined. Even if you could get 5,000,000
people living in it. That would be, at most, a productive workforce
of 3,000,000 people. That would mean constructing a mass of 11,174
tons of material per "economic person." Assign your own value to the
cost of that material - I just can't see it.

No, I think that Dyffed Neal Dyar is wrong with respect to his
physics. Proposing radiation protection greater than that for
nuclear power plants makes his whole scenario wrong. But he does
have a nice site where he pulls together information and tries to
address real world feasability issues. But he shouldn't be taken as
an authority and used to buttress arguments.

--- In spacesettlers@y..., "tomexe" wrote:
> --- In spacesettlers@y..., "Combs, Mike" wrote:
> > From: tomexe [mailto:tomexe@a...]
> >
> > But I for one have found the idea of storing water over the
windows
> > would serve as a radiation modifier, and would probably produce
> > more "natural" weather patterns inside the colony.
> >
> > Perhaps, but if at a high-orbital construction site, between 1
> million tons
> > of water, and one million tons of slag, I know which is going to
> cost more.
> >
> > Regards,
> >
> > Mike Combs
>
> Well here is the thing. I have been visiting this website
> http://silver.neep.wisc.edu/~neep533/neep533.html at the
> University of Wisconsin for information about space construction.
I
> frequently refer to the lectures of 17 Feb, and 15,17,19 March.
Its
> three years old now, but it still seems to be a good site. At
least I
> havent found a better one yet in scouring the internet.
>
> Acording to this, given the availability of enough electricity, to
> produce heat, water is not hard to come by on the moon. It can be
> acqured from the lunar soil.
>
> Slag may be what the solid areas of the colony are made out of.
This
> same design that has 40 foot thick glass windows also has 50ft of
> mooncrete or or slag bricks or both, making up the structure of
the
> solid panels and end caps. The actual thickness is actually more
than
> 50 feet because of access tunnels, but any partical trying to get
in
> would have to pass through 50 feet of materaial-before coming into
> contact with the landscaped topsoil yet. While particles trying to
> get in on the windows would have to pass through 40 feet of glass
and
> 4 miles of atmosphere to get to a person on the surface even
without
> water over the windows. Also the glass can be made denser than
just
> pure silicon. Leaded crystal, which mixes a couple percent of
> powdered lead with the sand, also has good light transmission
> qualities and would be denser.
>
> Water may be more expensive to gather in the short run, but it is
> reuseable, and has a lot of other functions than being a radiation
> blanket. It can be used to transport heat energy through the
colony,
> from the sunward endcap and the cylinders in the factory ring,
back
> to the cold endcap, moderating temperatures and also creating a
> current which could be tapped to provide even more electricity.
Using
> the mirrors as resevours would also humidify the atmosphere
inside,
> producing clouds and rain, a more natural habitat for the people,
> plants and animals inside. The free water vapor would serve to
> thicken the atmosphere inside and act as a further barrier to
> radiation.
>
> If you go to this page:
> http://silver.neep.wisc.edu/~neep533/LEC16/0slide.html the
last
> half dozen slides (47-53) have charts that explain the amount of
> cosmic background radiation exposure that a astronaut recieves on
> three different missions, one to a space station, one to the moon,
> and one to Mars, in a "standard" spacraft hull of 2g/cm2 Aluminum
> alloy. It does not allow for solar flare events. Compare this
with
> the shielding provided by such large thicknesses of concrete and
> glass. I think that for a Island 3 type colony only the endcap
that
> faced the sun all the time would require solar flare sheilding,
the
> rest of the colony would be in the shadow of that shield, and
would

--- In spacesettlers@y..., "victoriatangoman"
> The problem with relying on "appeal to authority" type arguments
is
> that there is no independent verification of results. While I
admire
> the work that Dyffed Neal Dyar did on his web page, I think it is
> troubling to be relying on the physics underlying a sci-fi site.
>
> Let's look at a few numbers to try to come to a better
understanding
> of the thicknesses involved in the pressure shell and the windows.
>
> The 50 feet of mooncrete and 40 feet of windows don't ring true
for
> me. When I consider the thickness of radiation shielding for a
> nuclear power plant and compare it to the above thicknesses, I'm
led
> to believe that something is askew.
>
> Also, the mass involved is staggering. Consider:
>
> 4*pi*r2 is surface area of sphere.
> 2*pi*r*L is surface area of a cylinder
>
> r = 2 miles * 5,280 feet = 10,560 feet
> L = 20 miles * 5,280 feet = 105,600 feet
>
> Two endcaps = 1,401,885,257 ft2
> Cylinder = 7,009,426,286 ft2
>
> The endcaps have no window area so they are 50 ft thick, thus
there
> is 70,094,262,860 ft3 of material.
>
> The cylinder is half window and half shell, therefore
>
> 3,504,713,143 ft2 * 40 = 140,188,525,700 ft3 of glass
> 3,504,713,143 ft2 * 50 = 175,235,657,100 ft3 of slag.
>
> Altogether, that is a volume of material, just for the shell not
> including any buildings or support structure insided the habitat
nor
> exterior mirrors and farming modules, of 385,518,445,086 ft3 of
> material.
>
> If we assign a mass of 173.9 lbs/ft3 (lunar regolith) to that
volume
> we end up with a mass of 33,523,343,040 tons.
>
> If we assume that this material must be launched from the surface
of
> the moon over a period of 20 years, then we're launching 53.1509
> tons per second, every second for that 20 years.
>
> Considering that 1 ft3 of lunar regolith takes 374 MW of energy to
> propel up to the 3000 m/sec escape velocity, the power required to
> launch that 53 tons per second will have to be 228.6 GW.
>
> That power has to be a good portion of what is available on the
> earth right now!!
>
> ALso, if the payload size from the mass launcher is no smaller
than
> 1 ft3, then we'll have to have 611 mass launchers firing once a
> second with no downtime at all for 20 years.
>
> For me to buy into the 50 ft/ 40 ft scenario, I'd have to be
> convinced why a habitat would need more shielding that a nuclear
> power plant, and even if I was convinced on that point, I'd then
> have to conclude that an Island 3 would never be built. EVER.
> Because the economics just wouldn't work based on the scale of
> operation I've just outlined. Even if you could get 5,000,000
> people living in it. That would be, at most, a productive
workforce
> of 3,000,000 people. That would mean constructing a mass of 11,174
> tons of material per "economic person." Assign your own value to
the
> cost of that material - I just can't see it.

Just one more thought. Let's apply a generous charge for energy -
how about 2 cents per kilowatt hour. 1 ft3 of lunar regolith at 374
MW, would take 103.89 kilowatt hours, for a cost of energy of 2.08
dollars. 11,174 tons per person would cost $266,996.52 JUST for the
energy to propel the mass of the payloads off of the lunar surface.
Now factor in the mining, base maintenance, SMF, fabrication costs,
etc. No, the 50ft/40ft model is too scaled up. It's overkill.

>
> No, I think that Dyffed Neal Dyar is wrong with respect to his
> physics. Proposing radiation protection greater than that for
> nuclear power plants makes his whole scenario wrong. But he does
> have a nice site where he pulls together information and tries to
> address real world feasability issues. But he shouldn't be taken
as
> an authority and used to buttress arguments.
>
> --- In spacesettlers@y..., "tomexe" wrote:
> > --- In spacesettlers@y..., "Combs, Mike" wrote:
> > > From: tomexe [mailto:tomexe@a...]
> > >
> > > But I for one have found the idea of storing water over the
> windows
> > > would serve as a radiation modifier, and would probably
produce
> > > more "natural" weather patterns inside the colony.
> > >
> > > Perhaps, but if at a high-orbital construction site, between 1
> > million tons
> > > of water, and one million tons of slag, I know which is going
to
> > cost more.
> > >
> > > Regards,
> > >
> > > Mike Combs
> >
> > Well here is the thing. I have been visiting this website
> > http://silver.neep.wisc.edu/~neep533/neep533.html at the
> > University of Wisconsin for information about space
construction.
> I
> > frequently refer to the lectures of 17 Feb, and 15,17,19 March.
> Its
> > three years old now, but it still seems to be a good site. At
> least I
> > havent found a better one yet in scouring the internet.
> >
> > Acording to this, given the availability of enough electricity,
to
> > produce heat, water is not hard to come by on the moon. It can
be
> > acqured from the lunar soil.
> >
> > Slag may be what the solid areas of the colony are made out of.
> This
> > same design that has 40 foot thick glass windows also has 50ft
of
> > mooncrete or or slag bricks or both, making up the structure of
> the
> > solid panels and end caps. The actual thickness is actually more
> than
> > 50 feet because of access tunnels, but any partical trying to
get
> in
> > would have to pass through 50 feet of materaial-before coming
into
> > contact with the landscaped topsoil yet. While particles trying
to
> > get in on the windows would have to pass through 40 feet of
glass
> and
> > 4 miles of atmosphere to get to a person on the surface even
> without
> > water over the windows. Also the glass can be made denser than
> just
> > pure silicon. Leaded crystal, which mixes a couple percent of
> > powdered lead with the sand, also has good light transmission
> > qualities and would be denser.
> >
> > Water may be more expensive to gather in the short run, but it
is
> > reuseable, and has a lot of other functions than being a
radiation
> > blanket. It can be used to transport heat energy through the
> colony,
> > from the sunward endcap and the cylinders in the factory ring,
> back
> > to the cold endcap, moderating temperatures and also creating a
> > current which could be tapped to provide even more electricity.
> Using
> > the mirrors as resevours would also humidify the atmosphere
> inside,
> > producing clouds and rain, a more natural habitat for the
people,
> > plants and animals inside. The free water vapor would serve to
> > thicken the atmosphere inside and act as a further barrier to
> > radiation.
> >
> > If you go to this page:
> > http://silver.neep.wisc.edu/~neep533/LEC16/0slide.html the
> last
> > half dozen slides (47-53) have charts that explain the amount of
> > cosmic background radiation exposure that a astronaut recieves
on
> > three different missions, one to a space station, one to the
moon,
> > and one to Mars, in a "standard" spacraft hull of 2g/cm2
Aluminum

Thanks for some calculations that put this into perspective.

From: victoriatangoman [mailto:tango_dancer@...]

For me to buy into the 50 ft/ 40 ft scenario, I'd have to be
convinced why a habitat would need more shielding that a nuclear
power plant, and even if I was convinced on that point, I'd then
have to conclude that an Island 3 would never be built. EVER.
Because the economics just wouldn't work based on the scale of
operation I've just outlined.

And in fact, one of the things I read just today while looking at the
Stanford Study was that when one scales up from Island 1 to Island 3, one
finds that the increase in structural mass, soil, and atmosphere results in
there no longer being a need for a separate radiation shield. And that for
this reason, habitats on the scale of Island 3 will become economical to
build before they would have otherwise.

In other words, building a habitat for 100x the population would not cost
100x as much.

Regards,

Mike Combs

From:
victoriatangoman [mailto:tango_dancer@...]

For me to buy into the 50 ft/ 40 ft scenario, I'd have to be
convinced why a habitat would need more shielding that a nuclear
power plant, and even if I was convinced on that point, I'd then
have to conclude that an Island 3 would never be built. EVER.
Because the economics just wouldn't work based on the scale of
operation I've just outlined.

And in fact, one of the things I read just today while looking at the Stanford Study was that when one scales up from Island 1 to Island 3, one finds that the increase in structural mass, soil, and atmosphere results in there no longer being a need for a separate radiation shield. And that for this reason, habitats on the scale of Island 3 will become economical to build before they would have otherwise.

In other words, building a habitat for 100x the population would not cost 100x as much.

Regards,
Mike Combs

Why just water, could we not use other liquid or
frozen forms of material which will perform the same
absorption?

Joe Russo
Helping make our space a better place.

OuterSpaceDevelopment Community: Read our story to
learn about a man from NASA that is helping to make
fiction into reality at

--- "Combs, Mike" wrote:

--- In spacesettlers@y..., "victoriatangoman"
> --- In spacesettlers@y..., "victoriatangoman"
> wrote:
> > The problem with relying on "appeal to authority" type arguments
> is
> > that there is no independent verification of results. While I
> admire
> > the work that Dyffed Neal Dyar did on his web page, I think it is
> > troubling to be relying on the physics underlying a sci-fi site.
> >
> > Let's look at a few numbers to try to come to a better
> understanding
> > of the thicknesses involved in the pressure shell and the
windows.
> >
> > The 50 feet of mooncrete and 40 feet of windows don't ring true
> for
> > me. When I consider the thickness of radiation shielding for a
> > nuclear power plant and compare it to the above thicknesses, I'm
> led
> > to believe that something is askew.
> >
> > Also, the mass involved is staggering. Consider:
> >
> > 4*pi*r2 is surface area of sphere.
> > 2*pi*r*L is surface area of a cylinder
> >
> > r = 2 miles * 5,280 feet = 10,560 feet
> > L = 20 miles * 5,280 feet = 105,600 feet
> >
> > Two endcaps = 1,401,885,257 ft2
> > Cylinder = 7,009,426,286 ft2
> >
> > The endcaps have no window area so they are 50 ft thick, thus
> there
> > is 70,094,262,860 ft3 of material.
> >
> > The cylinder is half window and half shell, therefore
> >
> > 3,504,713,143 ft2 * 40 = 140,188,525,700 ft3 of glass
> > 3,504,713,143 ft2 * 50 = 175,235,657,100 ft3 of slag.
> >
> > Altogether, that is a volume of material, just for the shell not
> > including any buildings or support structure insided the habitat
> nor
> > exterior mirrors and farming modules, of 385,518,445,086 ft3 of
> > material.
> >
> > If we assign a mass of 173.9 lbs/ft3 (lunar regolith) to that
> volume
> > we end up with a mass of 33,523,343,040 tons.
> >
> > If we assume that this material must be launched from the surface
> of
> > the moon over a period of 20 years, then we're launching 53.1509
> > tons per second, every second for that 20 years.
> >
> > Considering that 1 ft3 of lunar regolith takes 374 MW of energy
to
> > propel up to the 3000 m/sec escape velocity, the power required
to
> > launch that 53 tons per second will have to be 228.6 GW.
> >
> > That power has to be a good portion of what is available on the
> > earth right now!!
> >
> > ALso, if the payload size from the mass launcher is no smaller
> than
> > 1 ft3, then we'll have to have 611 mass launchers firing once a
> > second with no downtime at all for 20 years.
> >
> > For me to buy into the 50 ft/ 40 ft scenario, I'd have to be
> > convinced why a habitat would need more shielding that a nuclear
> > power plant, and even if I was convinced on that point, I'd then
> > have to conclude that an Island 3 would never be built. EVER.
> > Because the economics just wouldn't work based on the scale of
> > operation I've just outlined. Even if you could get 5,000,000
> > people living in it. That would be, at most, a productive
> workforce
> > of 3,000,000 people. That would mean constructing a mass of
11,174
> > tons of material per "economic person." Assign your own value to
> the
> > cost of that material - I just can't see it.
>
> Just one more thought. Let's apply a generous charge for energy -
> how about 2 cents per kilowatt hour. 1 ft3 of lunar regolith at 374
> MW, would take 103.89 kilowatt hours, for a cost of energy of 2.08
> dollars. 11,174 tons per person would cost $266,996.52 JUST for the
> energy to propel the mass of the payloads off of the lunar surface.
> Now factor in the mining, base maintenance, SMF, fabrication costs,
> etc. No, the 50ft/40ft model is too scaled up. It's overkill.
>
> > No, I think that Dyffed Neal Dyar is wrong with respect to his
> > physics. Proposing radiation protection greater than that for
> > nuclear power plants makes his whole scenario wrong. But he does
> > have a nice site where he pulls together information and tries to
> > address real world feasability issues. But he shouldn't be taken
> as
> > an authority and used to buttress arguments.
> >
> > --- In spacesettlers@y..., "tomexe" wrote:
> > > --- In spacesettlers@y..., "Combs, Mike" wrote:
> > > > From: tomexe [mailto:tomexe@a...]
> > > >
> > >
> > > >
> > > > But I for one have found the idea of storing water over the
> > windows
> > > > would serve as a radiation modifier, and would probably
> produce
> > > > more "natural" weather patterns inside the colony.
> > > >
> > > > Perhaps, but if at a high-orbital construction site, between
1
> > > million tons
> > > > of water, and one million tons of slag, I know which is going
> to
> > > cost more.
> > > >
> > > >
> > > > Regards,
> > > >
> > > > Mike Combs
> > >
> > > Well here is the thing. I have been visiting this website
> > > http://silver.neep.wisc.edu/~neep533/neep533.html at the
> > > University of Wisconsin for information about space
> construction.
> > I
> > > frequently refer to the lectures of 17 Feb, and 15,17,19 March.
> > Its
> > > three years old now, but it still seems to be a good site. At
> > least I
> > > havent found a better one yet in scouring the internet.
> > >
> > > Acording to this, given the availability of enough electricity,
> to
> > > produce heat, water is not hard to come by on the moon. It can
> be
> > > acqured from the lunar soil.
> > >
> > > Slag may be what the solid areas of the colony are made out of.
> > This
> > > same design that has 40 foot thick glass windows also has 50ft
> of
> > > mooncrete or or slag bricks or both, making up the structure of
> > the
> > > solid panels and end caps. The actual thickness is actually
more
> > than
> > > 50 feet because of access tunnels, but any partical trying to
> get
> > in
> > > would have to pass through 50 feet of materaial-before coming
> into
> > > contact with the landscaped topsoil yet. While particles trying
> to
> > > get in on the windows would have to pass through 40 feet of
> glass
> > and
> > > 4 miles of atmosphere to get to a person on the surface even
> > without
> > > water over the windows. Also the glass can be made denser than
> > just
> > > pure silicon. Leaded crystal, which mixes a couple percent of
> > > powdered lead with the sand, also has good light transmission
> > > qualities and would be denser.
> > >
> > > Water may be more expensive to gather in the short run, but it
> is
> > > reuseable, and has a lot of other functions than being a
> radiation
> > > blanket. It can be used to transport heat energy through the
> > colony,
> > > from the sunward endcap and the cylinders in the factory ring,
> > back
> > > to the cold endcap, moderating temperatures and also creating a
> > > current which could be tapped to provide even more electricity.
> > Using
> > > the mirrors as resevours would also humidify the atmosphere
> > inside,
> > > producing clouds and rain, a more natural habitat for the
> people,
> > > plants and animals inside. The free water vapor would serve to
> > > thicken the atmosphere inside and act as a further barrier to
> > > radiation.
> > >
> > > If you go to this page:
> > > http://silver.neep.wisc.edu/~neep533/LEC16/0slide.html
the
> > last
> > > half dozen slides (47-53) have charts that explain the amount
of
> > > cosmic background radiation exposure that a astronaut recieves
> on
> > > three different missions, one to a space station, one to the
> moon,
> > > and one to Mars, in a "standard" spacraft hull of 2g/cm2
> Aluminum
> > > alloy. It does not allow for solar flare events. Compare this
> > with
> > > the shielding provided by such large thicknesses of concrete
and
> > > glass. I think that for a Island 3 type colony only the endcap
> > that
> > > faced the sun all the time would require solar flare sheilding,
> > the
> > > rest of the colony would be in the shadow of that shield, and
> > would
> > > need only sheilding for cosmic background radiation.

Well, if it doesnt need to be that thick, so much the better! But
most of the threads here were about worring if it would need special
sheilding, and I think except for solar flare protection for the
sunward end, the hull construction alone would be adequate.

--- In spacesettlers@y..., "Combs, Mike" wrote:
> Thanks for some calculations that put this into perspective.
>
> From: victoriatangoman [mailto:tango_dancer@h...]
>
> For me to buy into the 50 ft/ 40 ft scenario, I'd have to be
> convinced why a habitat would need more shielding that a nuclear
> power plant, and even if I was convinced on that point, I'd then
> have to conclude that an Island 3 would never be built. EVER.
> Because the economics just wouldn't work based on the scale of
> operation I've just outlined.
>
> And in fact, one of the things I read just today while looking at
the
> Stanford Study was that when one scales up from Island 1 to Island
3, one
> finds that the increase in structural mass, soil, and atmosphere
results in
> there no longer being a need for a separate radiation shield. And
that for
> this reason, habitats on the scale of Island 3 will become
economical to
> build before they would have otherwise.
>
> In other words, building a habitat for 100x the population would
not cost
> 100x as much.
>
> Regards,
>
> Mike Combs

I thought so

After reading many of very enlightening posts about windows, shields and
other things with respects to building O'Neil colonies, I have come to a few
things. One, while we know a lot of many ways to build a colony, we have no
real solid facts on which actually work best both techincally and
economiclly. It seems to me that before we can even begin building a large
colony, we need to build smaller scale versions as research labs in various
aspects of space life and work. I would suggest starting with a simple torus
based on O'Neil farm ring and experiment with light, shielding, material, and
building methods and another for housing experiments. The farm ring could be
used for experiment with landscaping and lvestocks as well as crops. One
advantage to this beside the savings in trial and error experiments would be
having two additional source of income as both educational tourism site and
food output (the one that work that is) to hotels and stations, thereby
cutting down on their food budget. Together, we can learn what we need to do
before spending $20 billion on Island One!

Carl Mullin
www.ravenartstudio.com

Mike C wrote:
> when one scales up from Island 1 to Island 3, one finds that
>the increase in structural mass, soil, and atmosphere results in
>there no longer being a need for a separate radiation shield.

That's what I was looking for, as I followed this thread.
The figures of 50 feet hull, and 40 feet windows are just bonkers.

Somewhere back in the archives, I submitted a review of the "Concrete space
colonies" article. Shepard speculated on making blocks of window material of
equal thickness of the hull (~1.6 meter), but said that this was a complete
unknown.

I tossed a couple of drawings into a folder here.
The shielded windows are plagiarised from an article I ran across (No credits,
but I'll gladly include them if somebody slaps me across the face with info).
Picture 'slits' of windows like this going circumferentially around, on the "roof" in
a stanford torus. Basically the same effect as the old studies, but somewhat
more "streamlined" and simple. It's also more failsafe, with multiple panes of
glass to hold pressure.

We also went over the idea of "light pipes" here. Expand on the idea of a
channel or duct for light, with mirror to send light where you want. If a cylinder
has several sub-floor decks under the inner colony cvolume, then light can still
come in from "above" via light pipes.
Another thing to consider in looking over the old colony designs, is this: Do we
really need equal areas of window for a land surface? Couldn't light come in
through smaller areas through the "floor" above, and diffuse onto the land
opposite? This makes the windows smaller & less vulnerable, and saves
surface area for land & sub-floors.

The sphereoid colony is a compromise shape, allowing a large inner floor level
like a cylinder, but without the basic & inescapable instability of a cylinder.

Another quibble with something I've seen on these recent threads: The scarcity
of materials on the Moon, arguing against certain design features.
If we need thousands of tons of a latex sealant, then we'll import hydrocarbons
from an NEA. If we need several meters of H2O over the inner area for
radiation shielding, then we'll go to the NEAs, instead of Lunar topsoil (silly
idea! Even though it's based on real science, it's silly economics. Why soft-land
a nuclear rector to bake regolith, or use solar power which shuts down half of
the time, when there are floating mountains & icebergs just a few km/sec
away?)
Less delta-V than going to/from Luna typically, _FAR_ better resources, better
energy availability, instant colony location with everything you need to make
more colonies.

Really, every argument we use against the fanatical Martian fans, goes even
more for Luna. It's not even a good mine site!