There's a problem with tori I hadn't thought of: to minimize shielding mass you
need to wrap the spokes in shielding. That means they need to rotate. At
increases the structural strength requirements of the spokes immensely. Of
course, you could have the torus spin inside a stationary cylindrical shielding
mass, but then, why not make a thin cylinder?
Al Globus
aglobus@..., (650) 604-4404
http://www.nas.nasa.gov/~globus/home.html

The dinosaurs weren't spacefaring. We are. I don't think that's an accident.
Maybe we are life's taxi to the stars.

I think we should:

1. Devote half of NASA's budget ($7 billion) to reaching NASA's 2020 goal of
reducing launch costs to Low-Earth-Orbit to $220/kg with a 0.01% failure rate.
This should enable space tourism. The resulting orbital hotels will need to
develop efficient orbital life support and other necessary technologies.

2. Build orbital space colonies. The materials in the largest asteroid are
sufficient for orbital colonies with a combined surface area about 500 times
greater than Earth's. Eros alone could make over ten thousand space colonies,
each with about about 10 square kilometers of 1g living area.

3. After a few generations of orbital living, people won't need their colony
to be near Sol. Then small groups of colonies with populations in the
tens-of-thousands can set out on multi-decade journeys to nearby stars.

Except the launch goals, none of this is even a little bit official.

Al Globus wrote:

> There's a problem with tori I hadn't thought of: to minimize shielding mass you
> need to wrap the spokes in shielding. That means they need to rotate. At
> increases the structural strength requirements of the spokes immensely. Of
> course, you could have the torus spin inside a stationary cylindrical shielding
> mass, but then, why not make a thin cylinder?

Why not ditch the spokes? If a cylinder can survive without them so can
a torus can't it?

> --
> Al Globus
> aglobus@..., (650) 604-4404
> http://www.nas.nasa.gov/~globus/home.html

--
- Ian Woollard (ian.woollard@...)

"Is a planetary surface the right place for an expanding technological
civilization?"
- Gerard O'Neill

--- In spacesettlers@y..., Al Globus wrote:
> There's a problem with tori I hadn't thought of: to minimize
shielding mass you
> need to wrap the spokes in shielding. That means they need to
rotate. At
> increases the structural strength requirements of the spokes
immensely. Of
> course, you could have the torus spin inside a stationary
cylindrical shielding
> mass, but then, why not make a thin cylinder?
> --
> Al Globus
> aglobus@m..., (650) 604-4404
> http://www.nas.nasa.gov/~globus/home.html
>
> The dinosaurs weren't spacefaring. We are. I don't think that's an
accident.
> Maybe we are life's taxi to the stars.
>
> I think we should:

Hi Al,

>From what I understand of the Stanford Torus design the spokes have 3
functions.

1. Structural strength for the Torus (stiffening to help keep it's
shape with differential loading due to mass distribution of internal
structures)

2. Access for power feeds and heat exchange to outside radiators.

3. Human access to the torus itself.

Since human occupation of the spokes would be minimal I don't think
they need shielding. If shielding was required couldn't a shielded
elevator type affair suffice for the minimal time people would spend
in there?

Mark
>
> 1. Devote half of NASA's budget ($7 billion) to reaching NASA's
2020 goal of
> reducing launch costs to Low-Earth-Orbit to $220/kg with a 0.01%
failure rate.
> This should enable space tourism. The resulting orbital hotels will
need to
> develop efficient orbital life support and other necessary
technologies.
>
> 2. Build orbital space colonies. The materials in the largest
asteroid are
> sufficient for orbital colonies with a combined surface area about
500 times
> greater than Earth's. Eros alone could make over ten thousand space
colonies,
> each with about about 10 square kilometers of 1g living area.
>
> 3. After a few generations of orbital living, people won't need
their colony
> to be near Sol. Then small groups of colonies with populations in
the
> tens-of-thousands can set out on multi-decade journeys to nearby
stars.

Whatever is used to carry people from the centre to the torus would probably be
electrically powered, so it would be able to be shielded provided your willing
to add a little extra mass to it and give it a bit more power.

Although it may be considered deserible to have a way for people to move though
them when the power goes out (might happen, but unlikely).

The other possibility is active shielding, although that has problems of its
own.

--- Mark Collins wrote:

From: Al Globus [mailto:aglobus@...]

There's a problem with tori I hadn't thought of: to minimize shielding mass
you
need to wrap the spokes in shielding.

Do we really? I understand that the 6-ft thickness requirement is what's
needed to make a lifetime spent in the environment safe. Nobody would be
living inside the spokes. People would only spend a few minutes passing
through a couple of times a day, even assuming their job was at the hub.

I would leave them unshielded; I think this was the intention of the
Stanford Study as well. I do know that putting inadequate shielding on the
spokes would actually make them more hazardous than no shielding at all.

Alternately, shielding the elevators would take a lot less mass than
shielding the spokes.

Of
course, you could have the torus spin inside a stationary cylindrical
shielding
mass, but then, why not make a thin cylinder?

True. I don't see a problem with the idea of a bicycle-tire-shaped shield,
chevron shields in the windows, and unshielded spokes.

Regards,

Mike Combs

From:
Al Globus [mailto:aglobus@...]
There's a problem with tori I hadn't thought of: to minimize shielding mass you
need to wrap the spokes in shielding.

Do we really? I understand that the 6-ft thickness requirement is what's needed to make a lifetime spent in the environment safe. Nobody would be living inside the spokes. People would only spend a few minutes passing through a couple of times a day, even assuming their job was at the hub.

I would leave them unshielded; I think this was the intention of the Stanford Study as well. I do know that putting inadequate shielding on the spokes would actually make them more hazardous than no shielding at all.

Alternately, shielding the elevators would take a lot less mass than shielding the spokes.
Of
course, you could have the torus spin inside a stationary cylindrical shielding
mass, but then, why not make a thin cylinder?

True. I don't see a problem with the idea of a bicycle-tire-shaped shield, chevron shields in the windows, and unshielded spokes.

Regards,
Mike Combs

From: Ian Woollard [mailto:ian.woollard@...]

Why not ditch the spokes? If a cylinder can survive without them so can
a torus can't it?

In a spinning cylinder (or sphere), one can make their way up to the spin
axis and leave. In a torus with no spokes or hub, there would be no way to
come or go.

Regards,

Mike Combs

From:
Ian Woollard [mailto:ian.woollard@...]
Why not ditch the spokes? If a cylinder can survive without them so can
a torus can't it?

In a spinning cylinder (or sphere), one can make their way up to the spin axis and leave. In a torus with no spokes or hub, there would be no way to come or go.

Regards,
Mike Combs

To zero-G rec. you need to get to the center and have something there. To me this
is a killer trade. Space colonies must offer something unique and wonderful, e.g.,
0g rec. and the views. Otherwise, why not live on the ocean or in Antartica? They
have plenty of elbow room. Also, docking ports should probably be at the center of
rotation. In addition, manufacturing may wish to take advantage of various low-g
possibilities near the hub.

Ian Woollard wrote:

> Al Globus wrote:
>
> > There's a problem with tori I hadn't thought of: to minimize shielding mass you
> > need to wrap the spokes in shielding. That means they need to rotate. At
> > increases the structural strength requirements of the spokes immensely. Of
> > course, you could have the torus spin inside a stationary cylindrical shielding
> > mass, but then, why not make a thin cylinder?
>
> Why not ditch the spokes? If a cylinder can survive without them so can
> a torus can't it?
>
> > --
> > Al Globus
> > aglobus@..., (650) 604-4404
> > http://www.nas.nasa.gov/~globus/home.html
>
> --
> - Ian Woollard (ian.woollard@...)
>
> "Is a planetary surface the right place for an expanding technological
> civilization?"
> - Gerard O'Neill
>

Al Globus
aglobus@..., (650) 604-4404
http://www.nas.nasa.gov/~globus/home.html

The dinosaurs weren't spacefaring. We are. I don't think that's an accident.
Maybe we are life's taxi to the stars.

I think we should:

1. Devote half of NASA's budget ($7 billion) to reaching NASA's 2020 goal of
reducing launch costs to Low-Earth-Orbit to $220/kg with a 0.01% failure rate.
This should enable space tourism. The resulting orbital hotels will need to
develop efficient orbital life support and other necessary technologies.

2. Build orbital space colonies. The materials in the largest asteroid are
sufficient for orbital colonies with a combined surface area about 500 times
greater than Earth's. Eros alone could make over ten thousand space colonies,
each with about about 10 square kilometers of 1g living area.

3. After a few generations of orbital living, people won't need their colony
to be near Sol. Then small groups of colonies with populations in the
tens-of-thousands can set out on multi-decade journeys to nearby stars.

Except the launch goals, none of this is even a little bit official.

Combs, Mike wrote:

>
> *From:* Ian Woollard [mailto:ian.woollard@...]
>
> Why not ditch the spokes? If a cylinder can survive without them so can
> a torus can't it?
>
> In a spinning cylinder (or sphere), one can make their way up to the
> spin axis and leave. In a torus with no spokes or hub, there would be
> no way to come or go.

The shielding doesn't have to rotate. All that is needed is to enter
the shield and then accelerate upto the rotation speed and then dock.

> Regards,
>
> Mike Combs
--
- Ian Woollard (ian.woollard@...)

"Is a planetary surface the right place for an expanding technological
civilization?"
- Gerard O'Neill

depending on the author, habitat shielding requirements are 5 to 10 tons per square
meter (see
http://lifesci3.arc.nasa.gov/SpaceSettlement/75SummerStudy/Chapt4.html#Shielding
for one discussion). That seems like a lot to add to the elevator. It's possible
one could get by with less, but people might be reluctant to use the elevators
frequently if they felt they were being irradiated. In any case, it's one more
thing to add to the trade study.

Ryan Healey wrote:

> Whatever is used to carry people from the centre to the torus would probably be
> electrically powered, so it would be able to be shielded provided your willing
> to add a little extra mass to it and give it a bit more power.
>
> Although it may be considered deserible to have a way for people to move though
> them when the power goes out (might happen, but unlikely).
>
> The other possibility is active shielding, although that has problems of its
> own.
>
> --- Mark Collins wrote:
> > Hi Al,
> >
> > From what I understand of the Stanford Torus design the spokes have 3
> > functions.
> >
> > 1. Structural strength for the Torus (stiffening to help keep it's
> > shape with differential loading due to mass distribution of internal
> > structures)
> >
> > 2. Access for power feeds and heat exchange to outside radiators.
> >
> > 3. Human access to the torus itself.
> >
> > Since human occupation of the spokes would be minimal I don't think
> > they need shielding. If shielding was required couldn't a shielded
> > elevator type affair suffice for the minimal time people would spend
> > in there?
> >
> > Mark
>

Al Globus
aglobus@..., (650) 604-4404
http://www.nas.nasa.gov/~globus/home.html

The dinosaurs weren't spacefaring. We are. I don't think that's an accident.
Maybe we are life's taxi to the stars.

I think we should:

1. Devote half of NASA's budget ($7 billion) to reaching NASA's 2020 goal of
reducing launch costs to Low-Earth-Orbit to $220/kg with a 0.01% failure rate.
This should enable space tourism. The resulting orbital hotels will need to
develop efficient orbital life support and other necessary technologies.

2. Build orbital space colonies. The materials in the largest asteroid are
sufficient for orbital colonies with a combined surface area about 500 times
greater than Earth's. Eros alone could make over ten thousand space colonies,
each with about about 10 square kilometers of 1g living area.

3. After a few generations of orbital living, people won't need their colony
to be near Sol. Then small groups of colonies with populations in the
tens-of-thousands can set out on multi-decade journeys to nearby stars.

Except the launch goals, none of this is even a little bit official.

Mag Lev motors could probably get the power needed to move fully shielded
compartments out, although if there is at least 5 minutes warning then surely
we wouldn't really have much of a problem with the radiation.

Also I am wondering i it would be possible to somehow make the spokes part of
the radiation shield, the problem is that we would have to move the people up
to the speed of the pressure vessel with such a system, which might be harder
to solve then just having good warnings of solar flares.

--- Al Globus wrote:
> depending on the author, habitat shielding requirements are 5 to 10 tons per
> square
> meter (see
>
http://lifesci3.arc.nasa.gov/SpaceSettlement/75SummerStudy/Chapt4.html#Shielding

From: Ian Woollard [mailto:ian.woollard@...]

Combs, Mike wrote:

> In a spinning cylinder (or sphere), one can make their way up to the
> spin axis and leave. In a torus with no spokes or hub, there would be
> no way to come or go.

The shielding doesn't have to rotate. All that is needed is to enter
the shield and then accelerate upto the rotation speed and then dock.

Could probably be done that way, but wouldn't be as simple as a system which
was not dependent on a conveyance which speeded you up to match circular
velocity with the pressure vessel. Such a system would probably have to be
powered. In a sphere or cylinder, would could conceivably exit in an
emergency without use of any powered conveyances.

Regards,

Mike Combs

From:
Ian Woollard [mailto:ian.woollard@...]
Combs, Mike wrote:
> In a spinning cylinder (or sphere), one can make their way up to the
> spin axis and leave. In a torus with no spokes or hub, there would be
> no way to come or go.
The shielding doesn't have to rotate. All that is needed is to enter
the shield and then accelerate upto the rotation speed and then dock.

Could probably be done that way, but wouldn't be as simple as a system which was not dependent on a conveyance which speeded you up to match circular velocity with the pressure vessel. Such a system would probably have to be powered. In a sphere or cylinder, would could conceivably exit in an emergency without use of any powered conveyances.

Regards,
Mike Combs

Al Globus wrote:

> depending on the author, habitat shielding requirements are 5 to 10 tons per square
> meter (see
> http://lifesci3.arc.nasa.gov/SpaceSettlement/75SummerStudy/Chapt4.html#Shielding
> for one discussion). That seems like a lot to add to the elevator. It's possible
> one could get by with less, but people might be reluctant to use the elevators
> frequently if they felt they were being irradiated. In any case, it's one more
> thing to add to the trade study.

Ok. I'm probably missing something, aren't the astronauts in the ISS
being irradiated like this right now pretty much for months at
a time?

There are many ways to solve this problem, but it's not exactly instant
death to go into the elevator. I don't know about you, but most
people spend only a short time in elevators.

I would be more concerned with anyone who lives near the base of the
elevators, perhaps some kind of shielding would be required around
the base to ensure that no radiation reaches the rim down the shaft?

> --
> Al Globus
> aglobus@..., (650) 604-4404
> http://www.nas.nasa.gov/~globus/home.html

--
- Ian Woollard (ian.woollard@...)

"Is a planetary surface the right place for an expanding technological
civilization?"
- Gerard O'Neill

Al Globus wrote:

> To zero-G rec. you need to get to the center and have something there. To me this
> is a killer trade. Space colonies must offer something unique and wonderful, e.g.,
> 0g rec. and the views. Otherwise, why not live on the ocean or in Antartica? They
> have plenty of elbow room. Also, docking ports should probably be at the center of
> rotation. In addition, manufacturing may wish to take advantage of various low-g
> possibilities near the hub.

Suppose you pressure seal the torus shaped radiation shield. You have
a large pressurised non-rotating zero-g area to have fun in.

You can then have a rotating torus within it. Sure, it will take power
to keep it running. However, there's plenty of solar power, you can run
a heat engine of some kind to keep it turning, or an electric motor.

Zero-g when you want it. 1g when you don't.

> Ian Woollard wrote:
>
>> Al Globus wrote:
>>
>>
>>> There's a problem with tori I hadn't thought of: to minimize shielding mass you
>>> need to wrap the spokes in shielding. That means they need to rotate. At
>>> increases the structural strength requirements of the spokes immensely. Of
>>> course, you could have the torus spin inside a stationary cylindrical shielding
>>> mass, but then, why not make a thin cylinder?
>>
>> Why not ditch the spokes? If a cylinder can survive without them so can
>> a torus can't it?
>>
>>
>>> --
>>> Al Globus
>>> aglobus@..., (650) 604-4404
>>> http://www.nas.nasa.gov/~globus/home.html
>>
>> --
>> - Ian Woollard (ian.woollard@...)
>>
>> "Is a planetary surface the right place for an expanding technological
>> civilization?"
>> - Gerard O'Neill
>>
>>
>>
>>
>>
>
> --
> Al Globus
> aglobus@..., (650) 604-4404
> http://www.nas.nasa.gov/~globus/home.html
>
> The dinosaurs weren't spacefaring. We are. I don't think that's an accident.
> Maybe we are life's taxi to the stars.
>
> I think we should:
>
> 1. Devote half of NASA's budget ($7 billion) to reaching NASA's 2020 goal of
> reducing launch costs to Low-Earth-Orbit to $220/kg with a 0.01% failure rate.
> This should enable space tourism. The resulting orbital hotels will need to
> develop efficient orbital life support and other necessary technologies.
>
> 2. Build orbital space colonies. The materials in the largest asteroid are
> sufficient for orbital colonies with a combined surface area about 500 times
> greater than Earth's. Eros alone could make over ten thousand space colonies,
> each with about about 10 square kilometers of 1g living area.
>
> 3. After a few generations of orbital living, people won't need their colony
> to be near Sol. Then small groups of colonies with populations in the
> tens-of-thousands can set out on multi-decade journeys to nearby stars.
>
> Except the launch goals, none of this is even a little bit official.
>

--
- Ian Woollard (ian.woollard@...)

"Is a planetary surface the right place for an expanding technological
civilization?"
- Gerard O'Neill

--- In spacesettlers@y..., Ian Woollard wrote:
>
> Ok. I'm probably missing something, aren't the astronauts in the ISS
> being irradiated like this right now pretty much for months at
> a time?

The ISS is inside the Van Allen belts, which shield them from most of
the nasty radiation.

> There are many ways to solve this problem, but it's not exactly
> instant death to go into the elevator. I don't know about you,
> but most people spend only a short time in elevators.

Mostly likely this is true. But consider how much time we're talking
about: For a fairly large habitat (say, 1 mile in diameter), we're
talking an unshielded elevator length of about 2000 feet or so. I
expect we could run our elevator cars at 60 mph, or 88 fps, which
would require them to be in the unshielded part for about 22 seconds,
not counting accelleration/decelleration. Not sure what the
radiation levels are during a large solar flare, but it is unlikely
to kill you to take 22 seconds of that level. HOWEVER, it might make
your accumulated dosage to high to risk further exposure.

An alternative to tons of shielding on torus spokes, or no shielding
at all, would be to provide a minimal amount of shielding... one foot
instead of 10. Enough to knock out normal background levels, and
most everything except peak events. Then, accumulated exposures
don't add up to much except during the worst solar flares, and you
CAN see those coming (at least a few minutes ahead). The obvious
solution is to minimize elevator rides during heavy radiation.

> I would be more concerned with anyone who lives near the base of the
> elevators, perhaps some kind of shielding would be required around
> the base to ensure that no radiation reaches the rim down the shaft?

Taper the shielding from where the spoke enters the torus out for the
first 50 feet or so. The amount of radiation that could make its way
in at an angle will be small, and for short durations as the spoke
aims toward the sun. Even the, the far side of the torus will block
the worst of it, I would think.

Mike Eckardt
mike@...
http://orbitalhabitat.com

From: Al Globus
To:
Sent: Tuesday, March 27, 2001 8:48 PM
Subject: Re: [spacesettlers] Re: tori

> depending on the author, habitat shielding requirements are 5 to 10 tons
per square
> meter (see
>
http://lifesci3.arc.nasa.gov/SpaceSettlement/75SummerStudy/Chapt4.html#Shiel
ding
> for one discussion). That seems like a lot to add to the elevator. It's
possible
> one could get by with less, but people might be reluctant to use the
elevators
> frequently if they felt they were being irradiated. In any case, it's one
more
> thing to add to the trade study.
>

By the way, if the goal is simply to experience weightlessness, that can
also be done *inside* the torus (and therefore inside its shield, of
course). Imagine a track running along the torus circunferemce and a wagon
accelerating on that track in the direction opposite to the torus rotation.
When the velocity of the wagon equals the rotational velocitiy of the torus,
then the wagon is actually still, canceling the rotation - and people
onboard would be in weightlessness.

[snikt]
Lucio Coelho