Questions about "The High Frontier"

Damien Sullivan wrote:
Lofstrom launch loop. 2000 km long, 80 km high. Can rise pretty
straight, and above the atmosphere. No supervelocity needed.


Mind you it needs the total GDP of a country for a year or two to
build., and the effect of the winds of the jet stream on its support
structure would be interesting to see. :-D

Pat

Johnny1a wrote:

That doesn't make the effort totally wasted, it's fun, and it might
contribute something eventually to what actually does get built. For
an example, consider the early days of trans-atlantic air travel. An
idea that kept getting floated (literally) was to build artificial
islands in the midst of the ocean, to make air travel between North
America and Europe viable, since the planes could use them to refuel.
It never actually got built, because technology advanced to the point
that non-stop trans-Atlantic flight was viable without the islands.

But some of the thinking that went into that idea eventually went into
aircraft carriers.


Made of ice, no less: http://en.wikipedia.org/wiki/Project_Habakkuk

Pat

Johnny1a wrote:
By which I mean: is the best comparison for an operational O'Neill
Hab a city, or a ship? Ships at sea, for ex, are not and can not be
run democratically. The ship's master _might_, depending on the
situation, take the wishes of the crew into account in his decisions,
but that isn't democracy in the political sense.


Considering how these things seem to be geared toward the best and the
brightest...not to mention wealthiest... in Libertarian pipe dreams,
maybe a cruise ship might be a closer analogy. There's all the lads
thinking deep thoughts while the hired help under the strict command of
the captain actually does the dirty work that keeps the whole thing running.
Jules Verne came up with a idea somewhat like this in his story
"Propellor Island"; a huge ship full of rich people that is a nation
unto itself. Unfortunatly, a social breakdown occurs as the inhabitants
break down into two opposing groups:
http://www.fantasticfiction.co.uk/v/...ler-island.htm
I think he hit that right on the nose also...the people who would love
to move into a space habitat would be a bunch of individulists and
dreamers, and that would make for the biggest mess you ever saw, as no
one would want to be told what to do by anyone else. A army made up
entirly of generals.

I could imagine various social arrangements that _might_ work on an
O'Neill Hab other than dictatorship or strict military regimentation,
but I can't see any way to avoid the necessity for a very strong
executive and a state that can override individual wishes pretty
firmly and quickly. There wouldn't be much margin for error.


There could be a _lot_ that could go wrong on one of those things.

Pat

Johnny1a wrote:
By which I mean: is the best comparison for an operational O'Neill
Hab a city, or a ship? Ships at sea, for ex, are not and can not be
run democratically. The ship's master _might_, depending on the
situation, take the wishes of the crew into account in his decisions,
but that isn't democracy in the political sense.


Considering how these things seem to be geared toward the best and the
brightest...not to mention wealthiest... in Libertarian pipe dreams,
maybe a cruise ship might be a closer analogy. There's all the lads
thinking deep thoughts while the hired help under the strict command of
the captain actually does the dirty work that keeps the whole thing
running.
Jules Verne came up with a idea somewhat like this in his story
"Propeller Island"; a huge ship full of rich people that is a nation
unto itself. Unfortunately, a social breakdown occurs as the inhabitants
break down into two opposing groups:
http://www.fantasticfiction.co.uk/v/...ler-island.htm
I think he hit that right on the nose also...the people who would love
to move into a space habitat would be a bunch of individualists and
dreamers, and that would make for the biggest mess you ever saw, as no
one would want to be told what to do by anyone else. A army made up
entirely of generals.

I could imagine various social arrangements that _might_ work on an
O'Neill Hab other than dictatorship or strict military regimentation,
but I can't see any way to avoid the necessity for a very strong
executive and a state that can override individual wishes pretty
firmly and quickly. There wouldn't be much margin for error.


There could be a _lot_ that could go wrong on one of those things.

Pat

Johnny1a wrote:

I don't think an O'Neill Habitat would _have_ to be a fascist state.
It would not, however, lend itself well to the dreamy visions of
participatory democracy that have too often been coupled to it.

One interesting question about an O'Neill Habitat: is it a place, or
is it a vehicle?

By which I mean: is the best comparison for an operational O'Neill
Hab a city, or a ship? Ships at sea, for ex, are not and can not be

Dreams of the Culture notwithstanding, large habitats probably won't be
changing orbits very often or very quickly, so I think you can make a
case for "more like a climate controlled place".

run democratically. The ship's master _might_, depending on the
situation, take the wishes of the crew into account in his decisions,
but that isn't democracy in the political sense.

Why *can't* ships be run democratically? Especially as pirate ships
apparently were often pretty democratic. There's an executive who has
to be obeyed in combat, but is otherwise quite answerable to the ship's
assembly.

http://a4a.mahost.org/pirates.html
quoting _Raiders and Rebels_ says they didn't just elect captains, but
subjected most decisions to referendum. And it's not the only source.
If actual ships could run on such lines, I see no reason an O'Neill
colony couldn't be run via New England town meetings -- the early models
are just the right size for it, too.

-xx- Damien X-)

Johnny1a wrote:


I would like to see experiments done to establish just what levels of
gravitational attraction (or the equivalent) are necessary for Human
health, and what durations are dangerous. We just don't have the data
to make anything but WAGs on the subject as matters stand.

Agreed. Even more importantly, human tolerance to angular velocity
(revolutions per minute) needs to be determined.

Centrifugal force is w^2 * r, w being angular velocity and r being
radius. A 4-fold increase in w could mean a 16-fold decrease in radius.

Hop

Hop David wrote:

Agreed. Even more importantly, human tolerance to angular velocity
(revolutions per minute) needs to be determined.

Centrifugal force is w^2 * r, w being angular velocity and r being
radius.

That's centripetal/centrifugal acceleration, not force.

--
Erik Max Francis && && http://www.alcyone.com/max/
San Jose, CA, USA && 37 20 N 121 53 W && AIM, Y!M erikmaxfrancis
It's hard to say what I want my legacy to be when I'm long gone.
-- Aaliyah

Eivind Kjorstad wrote:

Hop David skreiv:


However small orbital hotels with artificial gravity may be possible. If
lunar gravity is sufficient to maintain health, the rotating hab radius
need only be 1/6 of the radius necessary for earth gravity.

Nyrath has mentioned recent research on tolerance to angular velocity.
It indicates humans can tolerate higher rpms if transition is gradual. 4
as opposed to 1 rpm would mean a sixteen fold difference in radius length.

So much smaller and less expensive rotating habs may be possible.


High-rpm-low-radius habs have a different problem though, the apparent
gravity inside them has a sharp gradient, and coriolis would be a bitch.

Early research had indicated sharp gradients and coriolis made
high-rpm-low-radius environments intolerable for workers. Nyrath (an
occasional RASS poster) has said recent research indicates higher
tolerance can be acquired if transition to a high rpm environment is
gradual.


Wouldn't it be easier to hang the hotel on a tether, with a counter-mass
on the other end, and spin it ? (the counter-mass can be a second hotel
if desired)

Indeed that's one of the structures I imagine. I call this a "bolo".
Another is two habs connected by a rigid length, I call this a "baton".

I expect most early rotating habs to be either bolos or batons.

Zubrin proposed a bolo for his Mars missions. Critics charged Zubrin
hadn't demonstrated a tether between a hab and a spent fuel tank would
be controllable. Waves and harmonics along the tether were a concern.

I believe a short tether would be easier to control. A shorter tether
would also be less expensive than a long tether.

A baton with a central airlock and rigid connecting lengths thick enough
to accomodate workers would be less of a problem to dock with than a
bolo. And in this case, short connecting lengths would certainly be less
expensive.

Hop

Matthias Warkus wrote:


People have held out in zero-g space stations for more than one year
without serious health problems AFAIK.


Yes and no. Long-term stays require extensive exercise while in orbit
(on the order of 2 hours a day).

If we start to build SPS and the like, almost certainly some form of
rotating stations (or at least sleeping quarters) will be built.


I'd think it cheaper to let people live in zero-g and put two hours of
mandatory daily exercise into their contracts.


There are other health problems associated with weightlessness that
exercise doesn't help:
http://en.wikipedia.org/wiki/Weightl...Health_effects

You also seem to be assuming rotating habs would be more expensive than
non-rotating habs. I've mentioned some factors that may make small
rotating habs workable. Do you have a reason to believe rotating habs
would be a lot more expensive?

Hop

Pat Flannery wrote:



Mike Combs wrote:

Seems to suggest that Winkler was being overly-conservative when he
insisted that anything over 1 RPM would be a mistake.



NASA did a study on this to determine the minimum diameter of a rotating
station where the crew wouldn't feel dizziness as they moved around in
it due to the perception of what "up" was, particularly in regards to
their inner ear.
IIRC, it was around 400 feet diameter for a 1g station.

Pat


400 feet = 122 meters, so the radius would be 61 meters.

w^2 * 61 meters = 9.8 meters/sec^2

w^2 = 9.8/61sec^2

w = .4 radians/sec = 3.8 RPM

Hop