> Hello. I am a builder of homes utilizing a construction process that
> makes concrete dome homes. We use a proprietary process that would be
> well suited for construction of bases of operation/living quarters for
> astronauts. The process could be easily automated, and could be
> finished by the time it is needed when the astronaut arrives. The
> cost of the building materials is comparable with a similar sized home
> of conventional construction materials.
>
It sounds neat. Where can we read more about this process? Would
you anticipate any problems with the materials in a vacuum?

Concrete tends to be strong in compression, but weak under tension.
A pressurized dome on, say, the Moon is under significant tension
(like a balloon). I worry that a concrete dome would blow out.
> My present interest is to do testing of the construction process
> underwater; so that we can refine the process to be used on other
> planets, and the moon. The reason that I would like to test it
> underwater, is so that we could test how well it would work as a
> closed ecosystem.
>
Well, I'd be less concerned with ecosystems and more concerned with
the basic physics of it. Unfortunately, underwater is a very
different environment than vacuum. I'm not sure what we would learn
from such a test.

Best,
- Joe

> Concrete tends to be strong in compression, but weak under tension.
> A pressurized dome on, say, the Moon is under significant tension
> (like a balloon). I worry that a concrete dome would blow out.

D.J. Sheppard thought that concrete would make a fine material from which to make an orbital habitat, provided in was run through with steel cables under tension to address the issue you raise. But although he referred to his proposed material as "concrete" I think it was actually a kind of cast basalt.
ref. D.J. Sheppard, "Concrete space colonies", Spaceflight 21: 3-8 (January 1979).

Regards,
Mike Combs

> Hello. I am a builder of homes utilizing a
> construction process that
> makes concrete dome homes.

I have seen a concrete dome home just outside Taos,
NM, and it is beautiful inside. Not that I think that
this is representative, but it does show what can be
done.

>We use a proprietary
> process that would be
> well suited for construction of bases of
> operation/living quarters for
> astronauts. The process could be easily automated,
> and could be
> finished by the time it is needed when the astronaut
> arrives. The
> cost of the building materials is comparable with a
> similar sized home
> of conventional construction materials.

Let's suppose that the dome you are building is on the
moon as an example. Would the raw materials for the
concrete or preformed panels of the concrete be
shipped up from the earth, or would the panels or
blocks be formed from lunar material? The answer to
this question changes the total cost of the structure
by a couple orders of magnitude, as the cost of
shipping is pretty high.

> My present interest is to do testing of the
> construction process
> underwater; so that we can refine the process to be
> used on other
> planets, and the moon.

It has been pointed out by others that underwater is a
very different environment than vacuum. However, if
this was being built on the moon one would then want
to cover the entire structure in several meters' depth
of lunar dust and rock for use as radiation shielding;
5 meters depth of lunar regolith would have a weight
about 25% in excess of the pressure inside the dome
(assuming 14.7 psi and 1/6 gee, and not counting the
weight of the dome itself). So yeah, it could be
built underwater, as long as your zenith is less than
2.5 meters from the surface of the water.

My only concern would be that once it is built, you
would have to pump the water out of the inside and
pump in air. It would require some pretty serious
ballast to keep it from floating. IIRC there is a
competition every year among university engineering
departments to build concrete boats, and what you are
proposing is in essence an immobile concrete
submarine. One wouldn't want to build this thing
underwater and then find out "oops! it pops to the
surface".

> The reason that I would like
> to test it
> underwater, is so that we could test how well it
> would work as a
> closed ecosystem.
>

Before going to testing it as a closed ecosystem, I
would be sure that you have a CELSS that works. One
of the chief lessons of the BiosphereII project was
that concrete absorbs oxygen as it cures. So, you
could start out your experiment with a beautiful dome
underwater that had an absolutely perfect ecosystem,
and have everything die or require oxygen input after
only a few months.

My suggestion is to build one of your concrete dome
homes on land, wait for the concrete to cure,
completely seal it inside and out, and then do your
ecosystem experiment aboveground. At least then you
can sell your concrete home after the experiment is
over.

Another suggestion is to have no windows in the
experimental ecosystem. Have everything growing under
artificial lighting so that you can meter energy usage
precisely. You may want to do a preliminary
experiment / literature search for the best type(s) of
artificial lighting to use in your experiment. Pay
particular attention to any literature you find about
growing marijuana indoors, as that is probably the
number one use of indoor artificial lighting optimized
for plant growth.

I expect that creating large mine shafts in a crater
rill would be a more effective approach to Lunar
housing.

GAry 7