From: spacesettlers@yahoogroups.com
[mailto:spacesettlers@yahoogroups.com] On Behalf Of ralph buttigieg

> If you want to properly conteract Zubrin design a colony of say,
> 100 people not 10,000 but can expand.

I think such a thing could be done with a baton geometry.

Regards,

Mike Combs

How important is it to have the option of expanding the same colony,
over a large size range, rather than building separate new colonies?

--- In spacesettlers@yahoogroups.com, "Combs, Mike"

From: spacesettlers@yahoogroups.com
[mailto:spacesettlers@yahoogroups.com] On Behalf Of Dan Wylie-Sears

> How important is it to have the option of expanding the same
> colony, over a large size range, rather than building
> separate new colonies?

That seems to be a recurring point of contention between the original,
1970's concepts of space habitats, and more recent attempts by some to
update the concept. In the original designs, it was considered no big
deal that you had to build the entire habitat before you could move in,
and that when expansion was desired it would be accomplished by building
another habitat, rather than by attempting to somehow enlarge the
original structure.

I still don't have a problem with it. It's important to remember that
even Earth-like habitats would start out at the Bernal Sphere or
Stanford Torus level, so expansion would occur in discrete units with
10,000 population capacity. Even by the time we've moved up to the
Island 3 stage, it's occurred to me that one needn't necessarily develop
the entire interior of a cylinder at once. One might initially only
develop one end of each of the three valleys, leaving the biggest length
of each unfinished (perhaps provided with soil but left without
landscaping or other furnishing), and then only grow down the length of
each valley as population increases.

For some reason, some more recent thinkers seem to feel that it's
vitally important for the habitat to be able to grow in size but remain
a single unit. And (as Ralph touched on) I've even had it argued to me
that we must settle Mars rather than orbital space because on Mars we
can expand incrementally, whereas in orbit we must always build a
completely new habitat to grow. (I'm unconvinced that this outweighs
the many good points O'Neill made about orbital locations.) Other than
its discrete vs. incremental nature, I'm not sure what the objection is
to a new habitat vs. enlargement of an existing one. Maybe people are
thinking about the fact that going from one habitat to another will
always involve "space travel". But I've often visualized a string of
co-orbiting habitats interconnected by a maglev system. In that case, I
don't see a big advantage to enlargement of an existing structure vs.
replication of the small structure you're living in. In fact, I can see
the many small structures as being safer in the sense of being more
segmented and isolated.

Coming back to my "baton" suggestion before, I suppose one might start
out with a two-armed baton, and then later expand it to four arms. One
might even do it without halting the rotation, if one was cautious about
keeping construction workers and equipment from "falling off" (being
flung off, actually). Then four arms might later get extended to six
and then to eight. Somewhere along this process it would be
advantageous to install curving tunnels that connected each sphere to
its neighbor, so that one needn't go all the way up to the spin axis
just to get from one sphere to the other (and can remain under normal
gravity for the entire trip). So one might start out with a baton, and
in the long run wind up with a torus-shaped bead necklace.

Regards,

Mike Combs

Zubrin like to say that the smallest O'Neill colony is "a billion
tons." But the NASA/Ames study at Stanford in the 1970's (the study
from which the Stanford Torus takes its name) suggested a one million
(that's "million" with an "m" not "billion" with a "b") ton colony
would be quite doable. There would be about ten million tons of slag
left over, which would be used for radiation shielding. So there you:
eleven million tons for Stanford Torus. Since 1976. I'm not sure
where Zubrin gets his numbers. Actually, I do have an idea, but
that's smelly.

Anyhoo, I have here the 1989 edition of _The High Frontier_, and on
pg. 324 Dr. O'Neill states: "A colony providing half of Earth's
gravity at its equator and rotating three
times per minute would bee 100 metres in diameter, would have the
right land area for 500 people, and would reqire a pressure hull of
only 700 tons. The smallest colony of the spacious, visually open
spherical design would be 60 metres in diametre, would house 150
people comfortably, and would require only 130 tons in its spherical
pressure shell. The necessary metel for it could be obtained from
external fuel tanks left in orbit from just four Space Shuttle Flights."

Even if one thinks that three or four RPM would be just be too danged
much, just throw in another 50 to 100 tons for kevlar cable, and there
you go. It is inaccurate to state that the "smallest O'Neill colony
is a billion tons," and inaccurate by multiple orders of magnitude.

From: spacesettlers@yahoogroups.com
[mailto:spacesettlers@yahoogroups.com] On Behalf Of Xenophile

> Zubrin like to say that the smallest O'Neill colony is "a billion
tons."

snip

> I'm not sure where Zubrin gets his numbers.

Zubrin used the habitat mass number that got him the results he was
after, i.e. the economics of this whole thing are laughable, so quit
bringing it up and let's all go back to the idea of colonizing Mars.

What I tell people about the one billion ton Island 3 is to not worry
about it, because Island 3 won't get built by Earth people or the
current civilization. Island 3 will get built by a future space-based
civilization which will get its start in much smaller and more modest
habitats.

Zubrin pretended that an Earth-based corporation wishing to make SPS in
space would first have to build Island 3. He even avoided referring to
the structure as "Island 3" because the very name itself makes explicit
that it would not represent a first generation habitat (not even the
first generation of Earthlike habitats).

I used to wonder if I was the only one who thought Zubrin was not above
sometimes making a disingenuous argument to make things come out his
way. I've since heard many others voice the same complaint, and in
various areas outside of Zubrin's rough treatment of O'Neill.

Regards,

Mike Combs

Do little things that you know are obviously going to succeed, and of course
do succeed, and get them one by one in the local newspaper, on the internet,
send out those press releases, etc.

And the point is made.

The purpose is published.

And you are building a record of success.. in that direction.

The direction is wherever you want to go, even a beautiful city in space.

On 1/12/06, Dan Wylie-Sears wrote:

--- In spacesettlers, "Combs, Mike" wrote:

> I used to wonder if I was the only one who thought Zubrin was not
> above sometimes making a disingenuous argument to make things come out
> his way. I've since heard many others voice the same complaint, and
> in various areas outside of Zubrin's rough treatment of O'Neill.
>
> Regards,
>
> Mike Combs

It may be 'disingenuous' to say "an O'Neill colony weighs a billion
tons," because after all there is one design that does, even though
the suggestion that they *all* mass a gigaton is not true. But to say
"the *smallest* O'Neill colony weighs a billion tons" is not
disingenuous, that's a lie.

From: spacesettlers@yahoogroups.com
[mailto:spacesettlers@yahoogroups.com] On Behalf Of Xenophile

> It may be 'disingenuous' to say "an O'Neill colony weighs a
> billion tons," because after all there is one design that does,
> even though the suggestion that they *all* mass a gigaton is
> not true. But to say "the *smallest* O'Neill colony weighs a
> billion tons" is not disingenuous, that's a lie.

To be honest, I don't think he said the smallest habitat would have to
weigh a billion tons. But he did imply that O'Neill's plan involved
building a billion ton habitat before commencing to build the first SPS
from space materials.

Regards,

Mike Combs