some comments on space colony habitat design (from Space Prizes and Contests)

Hi John,

Yes, what you say is true, however Al Globus uses
smaller cylinders inside the 1-gee outer cylinder for
a number of purposes. This detracts from the open sky
value that you mentioned, and we all agree it would be
very nice if we had access to unlimited resources. I
allocated 40% of the floor space be taken away for
open volume. If I changed it to 60% the sphere's
inhabitants would decrease by 1/3rd from 5200 to 3500,
and have a huge (vertical cylindrical shaped) open
volume at it center, the bottom could be a lake with
beaches. The inhabitants would live on mezzanine
floors surrounding the open space. I think it would
be quite nice and reminds me of the "Freedom Ship" a
very, very large cruise ship
(http://www.freedomship.com/) that was planned to
constantly circle the world every 2 years.

As for light, sunlight would be collected,
concentrated, selectively reflected several times,
then passed through several large windows probably of
multiple layers of glass and water. It could be
directed to a final interior mirror where it would
radiate quite similar to the sun we see on earth.

I don't advocate the dumbbell shape as the long thin
(elevator) tube to the smaller low- & zero- gee
spheres would waste precious resources. Instead I
would add shielded elevators that travel between the
main 1-gee sphere and the other smaller ones.

Although the size, mass and volume of the sphere is
smaller than the cylinder (and hence the shielding,
the atmosphere, and general resources to build are
smaller too), the external size is much larger, due to
the long tethers and counter weight. This could be
made into a platform and solar power could be
generated right there. In fact this platform, in made
into a circular disk, would measure about 12.5 square
Km. At 1350 W/m/m, This would amount to about 10
Megawatts (electric) if we use the new Diamond
thermionic conversion technology, with it's high
efficiency.

I admit I like the cylinders too, but from an
engineering standpoint the sphere would probably be
cheaper, faster and easier to build, and if we could
find some interior designers who could spruce it up,
it may be a shorter route to space colonies and
eventually the stars.

On another related issue, Al Globus says that below
the Van Allen Belts we would need 5 Tons of shielding
per square meter, and above it, around 10 Tons. A
quick calculation shows the mass of the atmosphere
above us on earth to be 10.357 Tons per square meter.
Long ago, during the cold war, I remember reading
somewhere that 10 feet of water would stop neutrons,
and all ionizing radiation up to and including cosmic
rays. 10' of water is 3.048 meters, hence at 1 Ton
(metric) per cubic meter, we would need only about 3
Tons per square meter if we used water for shielding.
IS THIS TRUE? If so, Hydrogen nuclei, must have
better stopping power then Nitrogen nuclei (pound for
pound).

Anyway if this is so, water would be a valuable
shielding material as it would reduce shielding mass
to less than 30% of other materials. I suppose I
should do a little research, but nah. I have other
things that need my attention.

regards,

Dave

--- ANTIcarrot wrote:

> > From: Dave Handwerk
> > 2. Al Globus claims the short cylinder is the best
> as
> > far as far as a comfortable living space verses
> mass
> > of shielding goes.
>
> If all you want is a massive towerblock in space,
> this is true. (This is in
> fact the kind of station we would want as a
> construction shack to build the
> lager ones.)

Yah, the 100 m diameter sphere for 650 people could do
the job nicely. D. H.