> That would make a near sun location my first choice were it is
> possible, to use direct sun irradiation to heat up the concrete. For
> instance using black painted forms for the parts of a bernal sphere
> and than place it in a appropriate distance to sun to get the positive
> overall temperature .
In space you can have any temperature you want, within reasonable limits. If you want low temperatures, use a sun shade. If you want heat, concentrate the sunlight with parabolic mirrors. If you want more heat, use a bigger mirror, or more than one.
In space you can have any temperature you want, within reasonable limits. If you want low temperatures, use a sun shade. If you want heat, concentrate the sunlight with parabolic mirrors. If you want more heat, use a bigger mirror, or more than one.
And in fact, for that very reason, I think cast basalt would be better for this application than wet setting cement. I'm sure wet cement will be used quite a bit in the interiors of space habitats, since the water which escapes during the drying process will remain a part of the biosphere. But if curing cement in space, the water vapor would be lost, and at least the hydrogen component of the water would be a little too pricey to tolerate that. There was a guy who wrotea paper for the Journal of the British Interplanetary Society (can't think of his name) who criticizedthe automatic assumption that space habitats will be built from aluminum as an example of "aerospace thinking". (In other words, "this thing is kinda like a big space ship, so we should build it out of the same materials we use for space ships".) His argument was that given the shielding requirements, we might as well go ahead and build space habitats out of prestressed concrete, which he felt had several advantages over metals for this application. But even though he used the term "concrete", I think what he was proposing was more along the lines of cast basalt. Solar mirrors could easily provide the heat necessary for casting.
Mike Combs
--- In ssi_list@... "Combs, Mike"
> Interplanetary Society (can't think of his name) who criticized the
> automatic assumption that space habitats will be built from
aluminum as an
> example of "aerospace thinking". (In other words, "this thing is
kinda like
> a big space ship, so we should build it out of the same materials
we use for
> space ships".) His argument was that given the shielding
requirements, we
> might as well go ahead and build space habitats out of prestressed
concrete,
> which he felt had several advantages over metals for this
application. But
> even though he used the term "concrete", I think what he was
proposing was
> more along the lines of cast basalt.
Mike,
I too am aware of this study. The author makes an excellent prima
facia case for concrete over aerospace.
Do you have any means to find out the author's name or the title of
the article?
I'd like to actually read the case he makes rather than relying on a
synopsis.
Preferrably I'd like an on-line citation to add to my collection,
but even a Journal citation would be fine. That's what libraries are
for :)
Hope you can help.
TangoMan
Message I don't have any issues of the JBIS, which is where his paper was published,but I'm pretty sure it gets treatment in "The Illustrated Encyclopedia of Space Technology, 2nd ed." by Kenneth Gatland, 1989, Orion Books, ISBN: 0-517-57427-8 which I do have. Tonight I'll look it up and give you the author's name, and maybe even a cite, Monday morning.
Mike,
I too am aware of this study. The author makes an excellent prima
facia case for concrete over aerospace.
Do you have any means to find out the author's name or the title of
the article?
I'd like to actually read the case he makes rather than relying on a
synopsis.
Preferrably I'd like an on-line citation to add to my collection,
but even a Journal citation would be fine. That's what libraries are
for :)
Hope you can help.
TangoMan
> And in fact, for that very reason, I think cast basalt would be
better for
> this application than wet setting cement. I'm sure wet cement will
be used
> quite a bit in the interiors of space habitats, since the water
which
> escapes during the drying process will remain a part of the
biosphere. But
> if curing cement in space, the water vapor would be lost, and at
least the
> hydrogen component of the water would be a little too pricey to
tolerate
> that.
>
> There was a guy who wrote a paper for the Journal of the British
> Interplanetary Society (can't think of his name) who criticized the
> automatic assumption that space habitats will be built from
> aluminum as an example of "aerospace thinking".
want to go too far into Mining metallurgy, but there are some very
basic misconceptions that I hear with respect to lunar materials.
The first one is that the various percentages of mettles reported by
the Apollo analysis are readily available..
Example of a false statement is "sample X from Apollo 15 had a
Aluminum Oxide content of 16%therefore we can use this to extract
aluminum". The fact is that, even on the moon, it would be very
costly to produce mass quantities of Aluminum with ore of this
quality. Aluminum and Calcium are very strongly bonded in minerals
such as orthoclase and plagioclase. You will commonly see in the
Apollo data a list of oxide percentages for each sample. These data
are designed to show bulk percentages of elements. They typically do
not show mineral phases present. On Earth, aluminum comes from ores
that are weathered clay minerals such as bauxite. I have yet to see
any data showing mineral phases that would be considered low quality
Aluminum ore.
Calcium (lime) has the same problem as aluminum. So, I have some
reservations about lunar concrete. Although, slag from other
processes could be reprocessed in to a similar but untested lime like
powder. I believe that if you tried to mass produce lunar concrete,
you would have mass quantities of ductile iron as a byproduct. A
little irony for you.
The easy materials to extract form moon rock are; Rock, glass,
oxygen, ductile iron and titanium.
> Aluminum may be the worst choice for a building material. I don't
> want to go too far into Mining metallurgy, but there are some very
> basic misconceptions that I hear with respect to lunar materials.
statement, so I'm assuming you've got a background in metallurgy
that most of us lack. I'm eager to delve into the details if you'd
spare some time and go into more details as to why you make the case
you do.
> The first one is that the various percentages of mettles reported
> by the Apollo analysis are readily available..
>
> Example of a false statement is "sample X from Apollo 15 had a
> Aluminum Oxide content of 16%therefore we can use this to extract
> aluminum". The fact is that, even on the moon, it would be
> very costly to produce mass quantities of Aluminum with ore of
> this quality.
Costly is relative, isn't it? If you need aluminum on the moon and
your alternative is to bring it all from Earth, then working with
anorthosite rather than bauxite is just a cost of doing business.
Also, who's your competition that's going to undercut your price?
> Aluminum and Calcium are very strongly bonded in minerals
> such as orthoclase and plagioclase. You will commonly see in the
> Apollo data a list of oxide percentages for each sample. These
data
> are designed to show bulk percentages of elements. They typically
do
> not show mineral phases present.
Would you elaborate the above comment? What amount of energy is
required to break the bonds, etc?
On Earth, aluminum comes from ores
> that are weathered clay minerals such as bauxite. I have yet to
see
> any data showing mineral phases that would be considered low
quality
> Aluminum ore.
>
> Calcium (lime) has the same problem as aluminum. So, I have some
> reservations about lunar concrete. Although, slag from other
> processes could be reprocessed in to a similar but untested lime
like
> powder. I believe that if you tried to mass produce lunar
concrete,
> you would have mass quantities of ductile iron as a byproduct. A
> little irony for you.
Why is this so? If you use anorthosite (CaAl2Si2O8)as your base
mineral, it is plentiful in the lunar highlands, and broke it down
into its constituent parts, you'd have your oxides of aluminum,
silicon and calcium, all of which are can be used in concrete.
Where does the iron come from? Do you mean ilmenite?
>
> The easy materials to extract form moon rock are; Rock, glass,
> oxygen, ductile iron and titanium.
How so?
Looking forward to your response.
TangoMan
TangoMan
of concrete or aluminum
Anorthosite is a rock not a mineral
Anorthosite is a mixture of other crystalline minerals;
Anorthite or calic-feldspare - Ca(Al2Si2O8)
Pyroxene - (Mg,Fe)SiO3
Olivine FESiO4
Since we don't have limestone, Anothosite would be a good choice of
rock for extracting calcium. And it is farley common on the moon.
Now if we have a sample of this rock and we melted it we would have
molten anorthosite and when it solidified we would have a fine
crystalline anorthosite. In order to get calcium or aluminum out of
the melt you would need use electrolysis and that would require shirt-
loads of electricity. The relative free energy needed to separate
oxygen from metals varies from metal to metal. The process of
electrolysis will remove the weaker bonded metals first such as iron,
potassium, phosphorus and Silicon. The most difficult metals to
separate are Al, Mg, and finally Ca. I have to be honest in that I
don't know why we would go though this to obtain lime for concrete.
If you need aluminum for wiring for your habitat, it would be worth
it. If you need mass quantities of aluminum for the pressure hull it
would not be worth it.
Lets talk about ductile iron. We humans have allot of experience
building things with iron. Because the Moon is a reduced
environment, there exists, native Iron in the soil. It could be
separated using a magnet. Iron also exists in ilmenite that can be
reacted with H2 to product native iron and TiO2. the H2 is
recyclable and the TiO2 is Ore quality.
Producing Iron will require considerably less energy than aluminum.
I don't believe that that there will be an unlimited amount of energy
on the moon. So, yes cost is relative, but aluminum on the moon does
not compete with aluminum from earth. I am comparing the cost in
energy compared with other lunar materials.
The molten basalt idea is intriguing because it only requires heat
which is much easier to come by than electricity.
more
> TangoMan
>
> I was responding specifically to the idea of building a habitat
out
> of concrete or aluminum
>
> Anorthosite is a rock not a mineral
> Anorthosite is a mixture of other crystalline minerals;
> Anorthite or calic-feldspare - Ca(Al2Si2O8)
> Pyroxene - (Mg,Fe)SiO3
> Olivine FESiO4
accurate :)
>
> Since we don't have limestone, Anothosite would be a good choice
of
> rock for extracting calcium. And it is farley common on the
moon.
Yes, especially in the Lunar Highlands.
> Now if we have a sample of this rock and we melted it we would
have
> molten anorthosite and when it solidified we would have a fine
> crystalline anorthosite.
I'm following you so far.
In order to get calcium or aluminum out of
> the melt you would need use electrolysis and that would require
shirt-
> loads of electricity.
Shirt-loads ? :) Don't you mean, well, ah, you know :)
The relative free energy needed to separate
> oxygen from metals varies from metal to metal.
I've uploaded this graphic to the Files section in the hopes that it
is relevant to our discussion.
http://f4.grp.yahoofs.com/v1/sGM0P3h-
1UhYGteNYNQoGBRH8OqY8C7TrG9FjMMCaj97g9waXXL9CX37nWxXPNweZLqH8Bq4vtGG3
gry4nOcb-PpIBzUDknB_yuGcA/Energy%20Requirements%20for%20Breaking%
20Lunar%20Oxides.jpg
You can unwrap the above URL and paste the entire thing into your
web browser or just go to the YahooGroups website and in the Files
section click on the file entitled:
Energy Requirements for Breaking Lunar Oxides.jpg
The process of
> electrolysis will remove the weaker bonded metals first such as
iron,
> potassium, phosphorus and Silicon.
Are we both on the same page here? Doesn't the energy requirement
for electrolysis refer to breaking the oxide bonds to seperate the
metal from the bound oxygen.
Surely the energy requirements would be considerably less for
extracting the oxides of calcium, silicon and aluminum from the
anorthite or feldspar?
A typical portland cement consists of 65% CaO, 23% SiO2, 4% Al2O3.
How much energy would be required to break the anorthite into these
constituent oxides?
The most difficult metals to
> separate are Al, Mg, and finally Ca. I have to be honest in that
I
> don't know why we would go though this to obtain lime for
concrete.
> If you need aluminum for wiring for your habitat, it would be
worth
> it. If you need mass quantities of aluminum for the pressure hull
it
> would not be worth it.
I'm in agreement with you on this point. Even though solar energy
will be free for the taking, it'll still require infrastructure to
use it.
Aluminum production is very energy intensive so that detracts from
it's merits.
Now processing ilmenite will yield Iron, Titanium and Oxygen.
Perhaps the Titanium can be used for the pressure hull because of
its light weight and high tensile strength. The Iron can be used
for the construction of SPS where it's mass won't be subjected to
centripetal forces and it's tensile strength would be irrelevant in
a Zero-g environment.
The Oxygen is used for the Habitat atmosphere and for propulsive
oxidizer.
Finally, after the Habitat shell is constructed, perhaps the
anorthite is now finally processed. Energy will be more readily
available becasue of the orbiting SPSs.
The anorthite will yield alumium which we may use in our Habitat
building construction in order to lessen building loads on the
pressure hull. Surely this would be better than iron girders.
The remaining silicon oxides and calcium oxides can be used for
Habitat internal ground cover and radiation shielding.
Thus all of the constituent parts of ilmenite and anthorite are
directed to specific purposes.
Having said all of the above, I'm still not sure about the metal-
concrete debate for Habitat shell construction.
> Lets talk about ductile iron. We humans have allot of experience
> building things with iron. Because the Moon is a reduced
> environment, there exists, native Iron in the soil. It could be
> separated using a magnet. Iron also exists in ilmenite that can be
> reacted with H2 to product native iron and TiO2. the H2 is
> recyclable and the TiO2 is Ore quality.
>
> Producing Iron will require considerably less energy than
aluminum.
> I don't believe that that there will be an unlimited amount of
energy
> on the moon. So, yes cost is relative, but aluminum on the moon
does
> not compete with aluminum from earth. I am comparing the cost in
> energy compared with other lunar materials.
Good point, but wouldn't you have to cover a lot of lunar area to
find the native iron in the soil?
> The molten basalt idea is intriguing because it only requires heat
> which is much easier to come by than electricity.
>
> more
Looking forward to more.
TangoMan
--- In ssi_list@... "Combs, Mike"
> quite a bit in the interiors of space habitats, since the water
which
> escapes during the drying process will remain a part of the
biosphere. But
> if curing cement in space, the water vapor would be lost, and at
least the
> hydrogen component of the water would be a little too pricey to
tolerate
> that.
I'm not so sure. A technique called Dry-Mix/Steam Injection was
developed that may address this very issue.
I've uploaded a file called Lunar Concrete to the Files section.
http://f3.grp.yahoofs.com/v1/sGM0P09ZoHZYGteNKwAouC1GIdgj5KGbFkMNoQpJ
-dvaQ43IB9blYDroJ4u-n5kloEgpz5fJqgvPvL6NwK6H7s40Rihd5dmj0O3F2Q/Lunar%
20Concrete.pdf
TangoMan
Message OK, here's the cite. I was wrong about the article being in the JBIS (probably was just remembering that the author was British), it was "Spaceflight". The author's name is D. J. Sheppard, and here's the cite: "Concrete Space Colonies" Spaceflight, Jan 1979
Mike Combs
I don't have any issues of the JBIS, which is where his paper was published,but I'm pretty sure it gets treatment in "The Illustrated Encyclopedia of Space Technology, 2nd ed." by Kenneth Gatland, 1989, Orion Books, ISBN: 0-517-57427-8 which I do have. Tonight I'll look it up and give you the author's name, and maybe even a cite, Monday morning.
Regards,
Mike,
I too am aware of this study. The author makes an excellent prima
facia case for concrete over aerospace.
Do you have any means to find out the author's name or the title of
the article?
I'd like to actually read the case he makes rather than relying on a
synopsis.
Preferrably I'd like an on-line citation to add to my collection,
but even a Journal citation would be fine. That's what libraries are
for :)
Hope you can help.
TangoMan
--- In ssi_list@... "Combs, Mike"
> OK, here's the cite. I was wrong about the article being in the
JBIS
> (probably was just remembering that the author was British), it was
> "Spaceflight". The author's name is D. J. Sheppard, and here's
the cite:
>
> "Concrete Space Colonies"
> Spaceflight, Jan 1979
TangoMan