Hi,

I was preparing a report on space settlements as a means of
colonization and came across the island one, two and three designs.
There seems to be some contradicting info on the web.

Wikipedia's entry says:

* Bernal sphere - "Island One"
(http://en.wikipedia.org/wiki/Bernal_sphere)

* Stanford torus - "Island Two"
(http://en.wikipedia.org/wiki/Stanford_torus)

* O'Neill cylinder - "Island Three"
(http://en.wikipedia.org/wiki/O%27Neill_cylinder)

and the space settlement FAQ by Mike Combs says the following -

A low-end design is Island One, also known as a Bernal Sphere.
Sunlight is reflected in through two ring-shaped rows of windows at
either end. Agriculture takes place in external tori. The Bernal
Sphere is 1 km (0.6 mi.) in circumference, and could support a
population of 10,000.
- This is consistent with Wikipedia's entry

Island Two is shaped like a cold capsule, with sunlight entering
through 3 windows running the length of the cylinder. 1.8 km (>1 mi.)
in diameter, it would house 140,000.
- contradicts the Wikipedia entry

A scaled-up version, Island Three, would be a cylinder 6.4 km (4 mi.)
in diameter and 32 km (20 mi.) long. Four miles of atmosphere is
enough to produce a blue sky overhead, and cloud banks would form at
the same level they do here on Earth (approx. 900 m or 3,000 ft).
Natural rainstorms would occur (Bernal Spheres would probably have a
sprinkler system). Island Three would have over 400 square km (250
square mi.) of living space, and be home to 10,000,000 individuals.

- doesn't really say what shape the structure it is, is this an
o'neill cylinder???

There are other designs as well. NASA's Ames Research Center did a
study with Stanford University which produced the Stanford Torus, a
six-spoked wheel over a mile across.
- Wikipedia says Island two is a stanford torus

If somebody could clarify the shapes of the various islands and their
capacities, it would be really helpful. In addition to that if you
could tell me about how expandable the above designs are, it would be
very helpful.

Thanks in advance
Saatvik Agarwal
High school student

I neve bothered with the 'Island' tags, and just referred to them in
increasing order of size:

Stanford Torus: shaped like a bicycle wheel and housing up to 10,000 people.
Actually, to avoid torque effects, there should be two wheels spinning in
opposite directions. Population would be 20,000. A whole wheel could be
used for agriculture.

http://lifesci3.arc.nasa.gov/SpaceSettlement/75SummerStudy/Table_of_Contents1.html

Bernal Sphere: the designs I've seen give it a radius of just under 900
meters and a population of 75,000. But there are also some that are smaller
and house around 10,000 people. Farms are placed in coiled rings along the
long axis outside the habitat.

http://www.l5news.org/bernalspheredetail.htm
http://www.l5news.org/bernalsphere.htm

O'Neil cylinder: shaped like a cold capsule, this habitat type depends on
how big you want to make it. There are some grandiose designs out there,
but why build a habitat to house 10 million people before you even know how
many people are going to want to live in that particular spot? Also, the
O'Neil cylinders should be built in linked pairs rotating in opposite
directions to avoid torque effects.
the first O'Neil cylinders will most likely be more modest sizes than
envisioned by O'Neil.

http://www.l5news.org/oneillcylinder.htm

As for expanding the various settlement types, the torus and cylinder are
the easiest. Just add another wheel to the torus (the axis is very long to
place reactors, factories and radiators away from the habitat), or another
"cold capsule" module onto the end of the cylinder. The Bernal Sphere is
not expandable -- you'd have to build a whole new habitat and attach it to
one end of the first habitat; might as well build a whole new town.

Thanks a lot Michael

The island tags do seem superficial now.

Which design would be most suitable for a colony of about 25,000-30,000 in orbit at L5? (If you could explain why too, it'll be really helpful)

Also you mention that the Stanford torus can accomodate 10,000-20,000, can't we construct a larger torus which can house about 30,000 people?

And do you think an O'Neill cylinder would be suitable for such a small population? Is it economically viable?

Thanks
Saatvik

Michael Capriola wrote:
I neve bothered with the 'Island' tags, and just referred to them in
increasing order of size:

Stanford Torus: shaped like a bicycle wheel and housing up to 10,000 people.
Actually, to avoid torque effects, there should be two wheels spinning in
opposite directions. Population would be 20,000. A whole wheel could be
used for agriculture.

http://lifesci3.arc.nasa.gov/SpaceSettlement/75SummerStudy/Table_of_Contents1.html

Bernal Sphere: the designs I've seen give it a radius of just under 900
meters and a population of 75,000. But there are also some that are smaller
and house around 10,000 people. Farms are placed in coiled rings along the
long axis outside the habitat.

http://www.l5news.org/bernalspheredetail.htm
http://www.l5news.org/bernalsphere.htm

O'Neil cylinder: shaped like a cold capsule, this habitat type depends on
how big you want to make it. There are some grandiose designs out there,
but why build a habitat to house 10 million people before you even know how
many people are going to want to live in that particular spot? Also, the
O'Neil cylinders should be built in linked pairs rotating in opposite
directions to avoid torque effects.
the first O'Neil cylinders will most likely be more modest sizes than
envisioned by O'Neil.

http://www.l5news.org/oneillcylinder.htm

As for expanding the various settlement types, the torus and cylinder are
the easiest. Just add another wheel to the torus (the axis is very long to
place reactors, factories and radiators away from the habitat), or another
"cold capsule" module onto the end of the cylinder. The Bernal Sphere is
not expandable -- you'd have to build a whole new habitat and attach it to
one end of the first habitat; might as well build a whole new town.

From: asaatvik [mailto:asaatvik@...]

> Island Two is shaped like a cold capsule, with sunlight entering
> through 3 windows running the length of the cylinder. 1.8 km
> (>1 mi.) in diameter, it would house 140,000.
>
> - contradicts the Wikipedia entry

Obviously I'll side with the Combs FAQ ;) but to the best of my
knowledge, the Wikipedia is mistaken in referring to the Stanford Torus
as Island 2. The Stanford Torus came out of the NASA-Ames/Stanford
study, and I'm pretty sure you can go through the entire report they
published without seeing any reference to "Island 2". They felt that
they were designing for the first permanent space habitat, not the
second generation. O'Neill, on the other hand, thought that a sphere
was a better choice for 1st generation space habitats. The Stanford
Torus population (10,000) compares to that of the Bernal Sphere, which
I'm pretty sure O'Neill, at least at a later point, referred to as
Island One.

> A scaled-up version, Island Three, would be a cylinder 6.4 km
> (4 mi.) in diameter and 32 km (20 mi.) long.
>
> - doesn't really say what shape the structure it is,

This has the same shape as the previously-mentioned structure i.e. a
cylinder with rounded end caps and three windows.

> is this an o'neill cylinder???

Yes, you can consider "O'Neill Cylinder" and "Island 3" to be
synonymous.

Regards,

Mike Combs

From: Michael Capriola [mailto:capcartoonist@hotmail.com]

> Stanford Torus: shaped like a bicycle wheel and housing up to 10,000
people.
> Actually, to avoid torque effects, there should be two wheels
spinning in
> opposite directions.

The NASA/Ames researchers didn't consider this to be a problem, as they
had arranged for the torus to rotate in the same plane as the orbit.
That's why the big oval mirror above is needed. It's the mirror that
tracks the sun, rather than the habitat.

Or alternately, one might try the same trick as with the Bernal Sphere:
spin the radiation shield in the opposite direction. It might need to
be a bit stronger in that case, but not a whole lot so since it would
only be rotating at around 1/10th the RPMs of the pressure hull.

Regards,

Mike Combs

From: Saatvik Agarwal [mailto:asaatvik@....uk]

> Also you mention that the Stanford torus can accomodate 10,000-20,000,

> can't we construct a larger torus which can house about 30,000 people?

Off the top of my head, I can't think of any reasons why the Stanford
Torus could not be scaled up some.

Regards,

Mike Combs

Saatvik Agarwal wrote:

"Which design would be most suitable for a colony of about 25,000-30,000 in
orbit
at L5? (If you could explain why too, it'll be really helpful)

"Also you mention that the Stanford torus can accomodate 10,000-20,000,
can't we
construct a larger torus which can house about 30,000 people?

"And do you think an O'Neill cylinder would be suitable for such a small
population? Is it economically viable?"

Okay, if we postulate a Stanford habitat needs two rings rotating in
opposite directions, and that half the area/volume must be set aside for
farming, then each torus wheel needs to be 1250 meters in radius (assuming a
minor radius for the tube of 65 meters); this allows 68m^2 per person in
surface area, just above NASA's optimum of 67m^2. The habitat would rotate
at 0.845 rpm.

A Bernal Sphere of 800meters radius can house 30,000 people at 134m^2 per
person. At 800 meters, the sphere rotates at 1.05 rpm. You don't want to
go much higher than 1rpm, which means you don't want to let your radius get
too small. A sphere of radius 575 can hold 30,000 people at 69m^2 per
person, but the rpm is now up to over 1.246. I'm not sure offhand what the
optimum level is to avoid extreme coriolis effects.

A double torus can do the job, but I'd elect for the 800 meter-radius Bernal
Sphere -- it has room to grow, being able top hold 60,000 people at 67^2 per
person (but see below).

The cylinder design doesn't seem to work for numbers this small. One
cylinder housing 30,000 people has a radius greater than its length. In
effect, it is a torus without the hole in the middle, and therefore wasteful
of material.

Also note that it is because we want to avoid unnecessary waste of
construction materials that the Stanford Torus is considered a better buy
than the Bernal Shpere. So, unless you plan on seeing the population double
in a short while, your best bargain is a double Stanford Torus 2.5 km
across.

Check out Election 2004 for up-to-date election news, plus voter tools and

From: Michael Capriola [mailto:capcartoonist@hotmail.com]

> Okay, if we postulate a Stanford habitat needs two rings rotating in
> opposite directions,

Please don't state this as a "need". It is not "necessary", as I
explained in another posting. Simply express it as your preference.

> Also note that it is because we want to avoid unnecessary waste of
> construction materials that the Stanford Torus is considered a better
buy
> than the Bernal Shpere.

It seems that you're picking your own unique dimensions for the
existing, published designs (your Stanford Torus is a bit smaller in
diameter, though you have two of them, and your Bernal Sphere is a good
deal larger). Not being an engineer, I can only work from the published
designs. The published designs for the Stanford Torus and the Bernal
Sphere had the same population (10,000; you're aiming higher), so that's
a basis for direct comparison. The masses listed in those studies were
10 million tons for a Stanford Torus and less than 4 million tons for a
Bernal Sphere.

As we scale upward, this ratio might change, but I don't really see it
reversing.

This would seem to suggest that a sphere is more efficient of building
materials than a torus. And I suspect that's the reason why O'Neill
presented the Bernal Sphere as a better alternative for a 1st generation
habitat than the Stanford Torus.

O'Neill came to different conclusions than the Ames Study because
someone on the Ames study felt strongly that any rotation rate beyond 1
RPM was asking for trouble. This pushed them toward a larger diameter,
and then toward reducing hull mass by going with a torus. O'Neill felt
we had good data supporting that up to 3 RPMs would be OK for most
people, and that 2 was a good compromise. So his 1st generation design
is a smaller-diameter sphere rotating around twice as fast.

Regards,

Mike Combs

Island Three: those huge, paired cylindars of O'Neil's.

Island Two: Bernal Sphere, about 1,800 metres in diameter.

Island One: Bernal Shere, about 500 metres in diameter OR...

Island One: Stanford Torus, about 1,800 metres in diameter.

There may be other contenders, but this is how I understand things.
I myself like the One = Turus, Two = Sphere, Three = Cylindar idea
best, simply because it gives a different shape for each of the three
stages.

My personal "tweak" on Island One increases the Stanford Torus
diameter to 2,000 metres, and the tube diameter (minor diameter?)
is... well...
http://f6.grp.yahoofs.com/v1/kA1sQase_MZ6ZiSuXS46DbX9x1GCjcUlpNO_O1u-
lv4y5FMc0xUU3pkpZv0M9D6tPmN94mTfD7bktt_o9wAhmFtet5hbq9dHVH0z/Island%
20One%20-%20CS-01.gif

The shorter (side-to-side) axis is 150 metres, the longer (up-and-
down) axis is 175 metres. The light is brought in via fiber optics.
As a lot of glass fibers are used in the construction of the hull, it
is no big deal to make more for use as optical fibers.

There is only one torus, because there doesn't need to be any
counterrotation. Or if there is need for that, then the radiation
shield (iron shell stuffed with slag) can be counterspun, as has been
pointed out in this thread.

Xenophile (who uses the advances made since the mid-70's as his
excuse for these changes)

"Combs, Mike" responding to
From: Michael Capriola [mailto:capcartoonist@...]

>Okay, if we postulate a Stanford habitat needs two rings rotating in
>opposite directions,

"Please don't state this as a "need". It is not "necessary", as I
explained in another posting. Simply express it as your preference."

Granted. I posted this before I saw your posting explaining how to avoid
torque effects.

>Also note that it is because we want to avoid unnecessary waste of
>construction materials that the Stanford Torus is considered a better
buy
>than the Bernal Shpere.

"It seems that you're picking your own unique dimensions for the
existing, published designs (your Stanford Torus is a bit smaller in
diameter, though you have two of them, and your Bernal Sphere is a good
deal larger)"

http://www.belmont.k12.ca.us/ralston/programs/itech/orbital/sphere.html
provides a java worksheet for creating habitat stats. The defaults for the
Torus and Sphere are set for populations of 10,000 and 75,000 respectively.
The radius of each would be 830 and 895 meters respectively. Scaling down
the sphere for a population of 10,000 (at 68m^2 per person surface area) we
find we only need a radius of 330 meters. The sphere would rotate at 1.645
rpm.

"O'Neill felt
we had good data supporting that up to 3 RPMs would be OK for most
people, and that 2 was a good compromise."

That answers my question about the coriolis effects. If 2 rpm is not going
to cause problems, then let's go with it.

Now for the big question: how accurate is the belmont site? Here's their
intro:

"PLEASE BE PATIENT WHILE JAVA APPLET LOADS. We will help you with the
calculations. First select the geometric shape of your design using the
radio buttons. Enter the population and physical dimensions (radius, length
etc) of your colony design. Press the button to calculate the corresponding
values. You can then "fine tune" your design by changing the gravity, air
pressure and energy per person. Many default values and calculations are
based on "Space Settlements-A Design Study" by NASA publications even though
any error(s) belong to Web authors. There may be slight differences between
the default values and the calculated values because of rounding off the
numbers. All units are in metrics. See also Regenerative Life Support
Systems for other calculations. For multi-component space settlement
illustrations see Figure 4-2 in Space Settlements."

The intro provides a link to "Space Settlements-A Design Study" by NASA
publications for those of you who do not own a copy, or (as in my case) are
too lazy to pull it off the bookshelf.

--- In spacesettlers@yahoogroups.com, "Michael Capriola"
wrote:

> Now for the big question: how accurate is the belmont site?

You can play around with this Excel file designed for creating a torus
Habitat. You can double check the math by looking at the formulas in
the cells.

http://tinyurl.com/4goyl

or get the file from the FILES section in the spacesettlers group website.

TangoMan

Hi,

Could you guys please explain what are the effects of torque which you've been talking about? Being a newbie to this field I wasn't quite sure.
And if torque has an effect on the motion of the space settlement can we ignore it (I presume not)?

QUOTE
>Okay, if we postulate a Stanford habitat needs two rings rotating in
>opposite directions,

"Please don't state this as a "need". It is not "necessary", as I
explained in another posting. Simply express it as your preference."

Granted. I posted this before I saw your posting explaining how to avoid
torque effects.
UNQUOTE

Assuming we can't ignore the effect of torque, am I correct in thinking that from the above you mean that either we can counterrotate the radiation shield or we can counterrotate one torus relative to the other (i.e. the second torus)?
Or can we ignore the effects of torque? Once again if you could explain what torque actually does in this case it would very helpful.

Michael -- in one of your posts you mentioned the following:

"A double torus can do the job, but I'd elect for the 800 meter-radius Bernal
Sphere -- it has room to grow, being able top hold 60,000 people at 67^2 per
person (but see below)."

I wasn't really clear what you meant by a double torus. Do you mean this - http://mathworld.wolfram.com/DoubleTorus.html
or do you just mean a torus stacked on top of another torus?

You guys are a great help.
Thanks and regards
Saatvik Agarwal

Michael Capriola wrote: "Combs, Mike" responding to
From: Michael Capriola [mailto:capcartoonist@...]

>Okay, if we postulate a Stanford habitat needs two rings rotating in
>opposite directions,

"Please don't state this as a "need". It is not "necessary", as I
explained in another posting. Simply express it as your preference."

Granted. I posted this before I saw your posting explaining how to avoid
torque effects.

>Also note that it is because we want to avoid unnecessary waste of
>construction materials that the Stanford Torus is considered a better
buy
>than the Bernal Shpere.

"It seems that you're picking your own unique dimensions for the
existing, published designs (your Stanford Torus is a bit smaller in
diameter, though you have two of them, and your Bernal Sphere is a good
deal larger)"

http://www.belmont.k12.ca.us/ralston/programs/itech/orbital/sphere.html
provides a java worksheet for creating habitat stats. The defaults for the
Torus and Sphere are set for populations of 10,000 and 75,000 respectively.
The radius of each would be 830 and 895 meters respectively. Scaling down
the sphere for a population of 10,000 (at 68m^2 per person surface area) we
find we only need a radius of 330 meters. The sphere would rotate at 1.645
rpm.

"O'Neill felt
we had good data supporting that up to 3 RPMs would be OK for most
people, and that 2 was a good compromise."

That answers my question about the coriolis effects. If 2 rpm is not going
to cause problems, then let's go with it.

Now for the big question: how accurate is the belmont site? Here's their
intro:

"PLEASE BE PATIENT WHILE JAVA APPLET LOADS. We will help you with the
calculations. First select the geometric shape of your design using the
radio buttons. Enter the population and physical dimensions (radius, length
etc) of your colony design. Press the button to calculate the corresponding
values. You can then "fine tune" your design by changing the gravity, air
pressure and energy per person. Many default values and calculations are
based on "Space Settlements-A Design Study" by NASA publications even though
any error(s) belong to Web authors. There may be slight differences between
the default values and the calculated values because of rounding off the
numbers. All units are in metrics. See also Regenerative Life Support
Systems for other calculations. For multi-component space settlement
illustrations see Figure 4-2 in Space Settlements."

The intro provides a link to "Space Settlements-A Design Study" by NASA
publications for those of you who do not own a copy, or (as in my case) are
too lazy to pull it off the bookshelf.

Hi, hope you don't me jumping in.

You wrote

"I wasn't really clear what you meant by a double torus. Do you mean
this - http://mathworld.wolfram.com/DoubleTorus.html
or do you just mean a torus stacked on top of another torus?"

If your trying to picture a double Torus just imagine two bicycle
wheels joined at the hub but rotating in opposite directions.The
space-station in the Film 2001 is a double Torus, the second Torus is
shown still under construction.

David

--- In spacesettlers@yahoogroups.com, Saatvik Agarwal
> Hi,
>
> Could you guys please explain what are the effects of torque which
you've been talking about? Being a newbie to this field I wasn't quite
sure.
> And if torque has an effect on the motion of the space settlement
can we ignore it (I presume not)?
>
> QUOTE
> >Okay, if we postulate a Stanford habitat needs two rings rotating
in
> >opposite directions,
>
> "Please don't state this as a "need". It is not "necessary", as I
> explained in another posting. Simply express it as your
preference."
>
> Granted. I posted this before I saw your posting explaining how to
avoid
> torque effects.
> UNQUOTE
>
> Assuming we can't ignore the effect of torque, am I correct in
thinking that from the above you mean that either we can counterrotate
the radiation shield or we can counterrotate one torus relative to the
other (i.e. the second torus)?
> Or can we ignore the effects of torque? Once again if you could
explain what torque actually does in this case it would very helpful.
>
> Michael -- in one of your posts you mentioned the following:
>
> "A double torus can do the job, but I'd elect for the 800
meter-radius Bernal
> Sphere -- it has room to grow, being able top hold 60,000 people at
67^2 per
> person (but see below)."
>
> I wasn't really clear what you meant by a double torus. Do you mean
this - http://mathworld.wolfram.com/DoubleTorus.html
> or do you just mean a torus stacked on top of another torus?
>
> You guys are a great help.
> Thanks and regards
> Saatvik Agarwal
>
> Michael Capriola wrote: "Combs, Mike" responding to
> From: Michael Capriola [mailto:capcartoonist@h...]
>
> >Okay, if we postulate a Stanford habitat needs two rings rotating
in
> >opposite directions,
>
> "Please don't state this as a "need". It is not "necessary", as I
> explained in another posting. Simply express it as your
preference."
>
> Granted. I posted this before I saw your posting explaining how to
avoid
> torque effects.
>
> >Also note that it is because we want to avoid unnecessary waste of

> >construction materials that the Stanford Torus is considered a
better
> buy
> >than the Bernal Shpere.
>
> "It seems that you're picking your own unique dimensions for the
> existing, published designs (your Stanford Torus is a bit smaller in
> diameter, though you have two of them, and your Bernal Sphere is a
good
> deal larger)"
>
> http://www.belmont.k12.ca.us/ralston/programs/it
ech/orbital/sphere.html
> provides a java worksheet for creating habitat stats. The defaults
for the
> Torus and Sphere are set for populations of 10,000 and 75,000
respectively.
> The radius of each would be 830 and 895 meters respectively.
Scaling down
> the sphere for a population of 10,000 (at 68m^2 per person surface
area) we
> find we only need a radius of 330 meters. The sphere would rotate
at 1.645
> rpm.
>
> "O'Neill felt
> we had good data supporting that up to 3 RPMs would be OK for most
> people, and that 2 was a good compromise."
>
> That answers my question about the coriolis effects. If 2 rpm is
not going
> to cause problems, then let's go with it.
>
> Now for the big question: how accurate is the belmont site? Here's
their
> intro:
>
> "PLEASE BE PATIENT WHILE JAVA APPLET LOADS. We will help you with
the
> calculations. First select the geometric shape of your design using
the
> radio buttons. Enter the population and physical dimensions (radius,
length
> etc) of your colony design. Press the button to calculate the
corresponding
> values. You can then "fine tune" your design by changing the
gravity, air
> pressure and energy per person. Many default values and calculations
are
> based on "Space Settlements-A Design Study" by NASA publications
even though
> any error(s) belong to Web authors. There may be slight differences
between
> the default values and the calculated values because of rounding off
the
> numbers. All units are in metrics. See also Regenerative Life
Support
> Systems for other calculations. For multi-component space
settlement
> illustrations see Figure 4-2 in Space Settlements."
>
> The intro provides a link to "Space Settlements-A Design Study" by
NASA
> publications for those of you who do not own a copy, or (as in my
case) are

From: Saatvik Agarwal [mailto:asaatvik@....uk]

> Could you guys please explain what are the effects of torque
> which you've been talking about?

When O'Neill was designing his first habitat (O'Neill Cylinder), he
quickly realized he had a problem. His design was dependent on the
habitat pointing continuously at the sun. But since the cylinder was
rotating, that made it a gigantic gyroscope. Gyroscopes tend to keep
pointing in one direction relative to the stars. Which means that a
single rotating cylinder would circle the sun like the pedal of a
bicycle when what was needed was for it to circle like the spoke of a
wheel.

O'Neill realized that he could solve the problem by having not one but
two cylinders of equal masses rotating in opposite directions. From an
angular momentum point of view, the two momentums cancel out and the
connected pair has 0 net angular momentum. Thus there's no problem with
the pair continuously turning to follow the sun (at the rate of about a
degree a day at our distance from the sun). There is a modest force
trying to turn each cylinder relative to the other. This can be
countered by a cable under tension at one end, and a tower under
compression at the other end. But these are relatively modest forces.
The cable would only be about the diameter of a teacup, and the tower
would be comparable to a radio mast.

Other habitat designs came up with other solutions. In both the
Stanford Torus, and in this design
(http://www.ssi.org/assets/images/Ch06p088.gif), the habitat spins in
the same plane as the orbit, and a large, oval-shaped mirror tracks the
sun rather than the habitat itself. In the Bernal Sphere, the radiation
shield is set counter-rotating relative to the pressure hull so that the
overall structure has 0 angular momentum (and so can continuously point
at the sun). Since the shield is something in the neighborhood of ten
times the mass of the pressure hull and its interior furnishings, it
doesn't need to rotate nearly as fast.

Regards,

Mike Combs

So I guess that for the Stanford torus we don't need to counterrotate
anything. Right?

Thanks and regards
Saatvik Agarwal

Combs, Mike wrote:

I'm not clear about what is better - the Stanford torus or the Bernal
sphere, or is there no clear answer?
Does the answer depend on RPM? If yes, what happens at 1 rpm and what
happens at 3 or 2 rpm?

Sorry for being such a pain but O'Neill's book isn't available in my
city, I looked for it everywhere...I've asked someone to bring it for me
from the US though.

Thanks once again and regards
Saatvik Agarwal

Combs, Mike wrote:

From: Saatvik Agarwal [mailto:asaatvik@....uk]

> So I guess that for the Stanford torus we don't need to counterrotate
> anything. Right?

Correct. (Unless we wanted to change it from a fixed, permanent habitat
into a roaming interplanetary vehicle, in which case it might be helpful
to be able to turn the axis when doing maneuvers. But if we plan on
leaving it in the orbit it was built in, then there should never arise a
need to turn the axis.)

Regards,

Mike Combs

From: Saatvik Agarwal [mailto:asaatvik@....uk]

> I'm not clear about what is better - the Stanford torus or the Bernal
> sphere, or is there no clear answer?

Depends on who you ask. The participants of the Stanford study probably
all think their design is better. I'm sure O'Neill felt the Bernal
Sphere was better. It does have a smaller mass budget for the same
population. I remember hearing him voice one complaint about the
Stanford Torus; you're dependent on elevators to get from the torus to
an exit. One thing that he liked about spheres and cylinders with
rounded end-caps was that a person could get up to the spin axis under
their own power in an emergency situation.

> Does the answer depend on RPM? If yes, what happens at 1 rpm and what
> happens at 3 or 2 rpm?

I believe Lawrence Winkler is the name of the Summer Study participant
who felt strongly that anything over 1 rpm was going to be trouble.
O'Neill felt that he could point to references indicating that most
people could adapt to 2 or even 3 RPMs. He settled on 2 for the Bernal
Sphere, and suggested that people simply be tested for unusual
susceptibility in the screening process until larger habitats came
on-line.

> Sorry for being such a pain but O'Neill's book isn't available in my
> city, I looked for it everywhere...I've asked someone to bring it for
me
> from the US though.

You can get it thought the web here
http://www.space-frontier.org/HighFrontier/ and here
http://www.amazon.com/exec/obidos/ASIN/189652267X/qid=1097764468/sr=2-1/
ref=pd_ka_b_2_1/002-7615123-5258465

Regards,

Mike Combs

--- In spacesettlers@yahoogroups.com, Saatvik Agarwal
> I'm not clear about what is better - the Stanford torus or the Bernal
> sphere, or is there no clear answer?
> Does the answer depend on RPM? If yes, what happens at 1 rpm and what
> happens at 3 or 2 rpm?
>
> Sorry for being such a pain but O'Neill's book isn't available in my
> city, I looked for it everywhere...I've asked someone to bring it
for me
> from the US though.
>
> Thanks once again and regards
> Saatvik Agarwal
>
To put it bluntly, we don't know. We can make good guesses. How good
is another question. I got my engineering degree in 1968. Computer
aided design was just starting.

Computers are nice, but there is no substitute for building a working
prototype and testing it to destruction. It is impractical to do this
with something as big as as a torus or sphere.

But I still believe that we will have to build a few and use them a
while before we understand all the advantages and disadvantages. We
will probably have to fix stuff as we go.

The trouble with a computer model is that you need to put in all the
factors. Miss some and your answer will be distorted. Miss an
important factor and your answer will probably be useless.

It's good to do the theory work first and it will clear up a lot of
potential problems. But I can't believe that it will clear up all the
problems.

It would be very good if we could solve everything on the ground. But
I'm afraid, we will have to go out there and muddle through as best we
can.

Rick Brooks

--- In spacesettlers, "Richard" wrote:

> To put it bluntly, we don't know. We can make good guesses. How
> good is another question. I got my engineering degree in 1968.
> Computer aided design was just starting.
>
> Computers are nice, but there is no substitute for building a
> working prototype and testing it to destruction. It is impractical
> to do this with something as big as as a torus or sphere.
>
> But I still believe that we will have to build a few and use them a
> while before we understand all the advantages and disadvantages. We
> will probably have to fix stuff as we go.
>
> The trouble with a computer model is that you need to put in all the
> factors. Miss some and your answer will be distorted. Miss an
> important factor and your answer will probably be useless.
>
> It's good to do the theory work first and it will clear up a lot of
> potential problems. But I can't believe that it will clear up all
> the problems.
>
> It would be very good if we could solve everything on the ground.
> But I'm afraid, we will have to go out there and muddle through as
> best we can.
>
> Rick Brooks

One thing that makes me feel better about all this is that we are
unlikely to jump from ISS to Island One. There will be some space
hotels, industrial facilities, millitary facilities, etc. But even
with all that, I'd rather live in the second Island One than in the
first. Maybe the fifteenth.

Xenophile (who would live in the first rather than none at all)

Saatvik Agarwal queried about the "double torus."

Sorry if I wasn't more explicit. Hmmm, it could look like the space
station from the movie "2001: A Space Oddyssey" except that the two
rings/wheels would rotate in opposite directions to cancel out torque
effects.

Dont just search. Find. Check out the new MSN Search!

From: Saatvik Agarwal wrote:

"I'm not clear about what is better - the Stanford torus or the Bernal
sphere, or is there no clear answer?
Does the answer depend on RPM? If yes, what happens at 1 rpm and what
happens at 3 or 2 rpm?"

The site listed here

http://lifesci3.arc.nasa.gov/SpaceSettlement/teacher/materials/ringworld/ringworld.html

can give you an example of what happens to objects in a spinning habitat.

If spinward is to my left, and I toss a ball to you, in which direction do
you move in order to catch the ball? And the faster the spin, the greater
the distance the ball travels away from you.

But the basic problem of too rapid a spin lies in what it does to your
inner ear. Hard to get any work done if you're dizzy all of the time. Even
in a spinning habitat that doesn't bother you when you are standing still, a
sudden move in the wrong direction could bring on an attack of dizziness.

And the reason we can't say for sure what happens at 3 rpm or 2 rpm is that
we haven't tested it. Everyone reacts differently. At the other end of the
scale, 0 rpm causes one-third of people affected to become nauseous. So
it's anybody's guess at this point.

From: Michael Capriola [mailto:capcartoonist@hotmail.com]

> And the reason we can't say for sure what happens at 3 rpm or 2 rpm is
that
> we haven't tested it.

Well, let's say we haven't tested it in space. There have been
Earthbound experiments. The question is to what extent the experimental
results we get here on Earth would apply in space.

Personally, I can't help but wonder if we'll find that adapting to spin
in space is easier than on Earth. On Earth, gravity is an additional
force acting on the inner ear. In space, that'd be one less force to
complicate things.

Regards,

Mike Combs

In a message dated 10/11/04 3:01:01 AM, asaatvik@... writes:

>

I don't agree, you need a simple catchy name to communicate the idea of
orbital settlements to people who are not as well informed as we are.

Carl E. Mullin
visionary artist and entrepreneur
homo asteralis
ravenart@...
www.ravenartstudio.com

The more you love, the more you can love-and the more intensely you love.
Nor is there any limit on how many you can love.
If a person had time enough, he could love all of the majority who are decent
and just.
-Robert A. Heinlein (Time Enough For Love)

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obliteration." -- Dune

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