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Questions about "The High Frontier"



 
 
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  #281  
Old October 24th 07, 07:10 PM posted to rec.arts.sf.science,sci.space.history
Mike Combs[_1_]
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Default Questions about "The High Frontier"

"Pat Flannery" wrote in message
...

Still a significant amount of energy required per kilogram of material
ending up in HEO.
At some point it makes more sense just to shoot it up from Earth, or at
least from the Moon.


The energy per kilogram is exactly the point. One figure I know off the top
of my head is that such energy costs from the moon to HEO are 1/20 the cost
as from the Earth. And there are some NEAs where the delta-V is even lower
than for the moon. The moon might compete with asteroids if the market is
in HEO, and if the desired material is oxygen, silicon, iron, or aluminum.
The Earth probably won't be able to compete for anything other than stuff
like computer systems or certain kinds of precision (and low-mass) parts.

The other problem is mining the asteroids per-say... solar flux at that
distance is a lot lower than here on Earth, so a major source of free
energy is not as effective.


Making concentrating mirrors bigger ought to be easy in free fall. Having
to double or triple your mirror area might not add that much to your total
material costs since the mirror can be very flimsy.

If you are going to try and colonize them, then it makes more sense just
to leave the material right in the orbit it's in, and build your colonies
out in the asteroid belt itself, rather than using all the energy to move
it inwards toward Earth.


Long-term, I'm sure you're right. But short-term the goal will not be
colonization, it will be making a profit by serving an existing market.
(The colonization will more or less happen as a consequence, not as the
original goal.) So I think asteroidal material will be moved into Earth
orbits because I think the initial enterprises will want to be close to the
markets they serve, and at the onset that's going to be Earth.

But then later on down the road, when commerce with Earth becomes the
smaller part of the space economy, yeah, it makes lots of sense to build
habitats in the Belt. Long-term, more may be built there than anywhere
else.

The Moon is a lot closer at hand for mining, you can walk and drive around
on it, it has a lot more sunlight falling on it, and you have a reasonable
transit time to and from Earth.


The last argument is the strongest.

One of the big problems of this scenario though is that it presumes that
humanity will continue growing in numbers like yeast colonies and
eventually run out of room on Earth to live.


I would agree that, contrary to the expectations of some early 70's-era
supporters, space habitats will not get built to relieve overcrowding on
Earth. They will get built when we become serious about pursuing a destiny
beyond the Earth. But that said, space habitats will permit the formation
of a space-based civilization which may outgrow our planetary one by several
orders of magnitude.

or, in a different timeline, turn the bipedal apes into servants, with
hilarious results somewhere down the line when they learn to speak, and
begin to plot against us. :-)


Heh. I was starting to flash on the current network TV sitcom "Cavemen"
(Neanderthals coexist with modern Homo Sapiens, with hilarious results)
before I saw where you were going with that.

--


Regards,
Mike Combs
----------------------------------------------------------------------
By all that you hold dear on this good Earth
I bid you stand, Men of the West!
Aragorn


  #282  
Old October 24th 07, 07:10 PM posted to rec.arts.sf.science,sci.space.history
Johnny1a
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Default Questions about "The High Frontier"

On Oct 24, 12:32 pm, Pat Flannery wrote:
Hop David wrote:

We're talking about payloads sent from an asteroid, not the entire
asteroid. The former is much more plausible than the latter.


Still a significant amount of energy required per kilogram of material
ending up in HEO.
At some point it makes more sense just to shoot it up from Earth, or at
least from the Moon.
The other problem is mining the asteroids per-say... solar flux at that
distance is a lot lower than here on Earth, so a major source of free
energy is not as effective.
The other thing is that with there low gravity fields getting around on
them is going to be more like EVAing than driving or walking.
If you are going to try and colonize them, then it makes more sense just
to leave the material right in the orbit it's in, and build your
colonies out in the asteroid belt itself, rather than using all the
energy to move it inwards toward Earth.
The Moon is a lot closer at hand for mining, you can walk and drive
around on it, it has a lot more sunlight falling on it, and you have a
reasonable transit time to and from Earth.
One of the big problems of this scenario though is that it presumes that
humanity will continue growing in numbers like yeast colonies and
eventually run out of room on Earth to live.
There's no particular reason for that to be the case, as Spartan Condoms
are cheaper than Space Colonies.
Dropped to about 1/2 - 3/4 its present size by natural mortality and
lowered birth rates over the next century if desired, there's no reason
that the human population of Earth...particularly given new sources of
renewable energy and recycling of materials... can't be quite happy and
stable for the next few millenia.


Population growth rates aren't controlled by the availability of birth
control. In fact, nobody knows what determines population growth and
decrease rates once the basic necessities of life are covered, they
seem to follow a logic of their own.

  #283  
Old October 24th 07, 07:12 PM posted to rec.arts.sf.science,sci.space.history
Hop David
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Posts: 656
Default Questions about "The High Frontier"

Pat Flannery wrote:



Hop David wrote:


We're talking about payloads sent from an asteroid, not the entire
asteroid. The former is much more plausible than the latter.



Still a significant amount of energy required per kilogram of material
ending up in HEO.
At some point it makes more sense just to shoot it up from Earth, or at
least from the Moon.


The earth is a steep gravity well with substantial atmospheric drag and
gravity penalty.

The moon has a shallower gravity well and no atmosphere. I believe the
moon is the best source of oxidizer.

Perhaps the lunar poles will provide other rocket fuel components and
reaction mass, but I don't regard it as a given. If the moon is volatile
poor then near earth asteroids, Phobos and Deimos could be the best
source of hydrogen and hydrogen compounds.

For various delta vee distances see
http://clowder.net/hop/railroad/deltaveemap.html


The other problem is mining the asteroids per-say... solar flux at that
distance is a lot lower than here on Earth, so a major source of free
energy is not as effective.


We've been talking about NEOs, not main belt asteroids. Some NEOs get
_more_ solar flux than earth.

The other thing is that with there low gravity fields getting around on
them is going to be more like EVAing than driving or walking.


This is a good point. Learning how to get along with no gravity is a
substantial obstacle.


If you are going to try and colonize them, then it makes more sense just
to leave the material right in the orbit it's in, and build your
colonies out in the asteroid belt itself, rather than using all the
energy to move it inwards toward Earth.


Initially, I don't think they'd be colonized at all if they had no
useful export to terrestial or near terrestial markets.

The Moon is a lot closer at hand for mining, you can walk and drive
around on it, it has a lot more sunlight falling on it, and you have a
reasonable transit time to and from Earth.


I got nothing against the moon. FWIW here's my current list of favorite
low hanging fruit:

1) Moon
2) Phobos & Deimos
3) NEOs
4) Mars

in that order.

One of the big problems of this scenario though is that it presumes that
humanity will continue growing in numbers like yeast colonies and
eventually run out of room on Earth to live.


I don't see space development as a way to deal with population growth
but as a way to increase options.

Of course, if we do settle NEOs and then the main belt, the population
ceiling could increase by a factor of thousands.

Hop
  #284  
Old October 24th 07, 07:22 PM posted to rec.arts.sf.science,sci.space.history
Johnny1a
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Posts: 25
Default Questions about "The High Frontier"

On Oct 23, 9:16 am, Hop David wrote:


While CCs may be poor in some those materials, there are other asteroids
that aren't.

I acknowledge that one asteroid containing all these resources would be
rare. It would be hard for colonists on a metallic asteroid to use
nitrogen from an NEO on a different orbit.

On the other hand, there's no superhighways, oceans or rivers that can
be used for transportation on Mars. Transportation will be a substantial
barrier to self sufficiency on Mars as well as among the NEOs.


But once an initial presence is established on Mars, i.e. a
functioning town or other colony, constructing such (superhighways or
the equivalent) is a relatively straightforward project, in comparison
to establishing a viable interplanetary transport system between the
asteroids.


  #285  
Old October 24th 07, 08:10 PM posted to rec.arts.sf.science,sci.space.history
Pat Flannery
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Posts: 18,465
Default Questions about "The High Frontier"



Johnny1a wrote:
Mike, you're a good guy and everything, but the above is a textbook
example of thinking with your heart instead of your head. In any
other context except space (you yourself bring up oil rigs) you
would quickly recognize the absurdities. But since this is space
we're talking about...well, things are different in space, right?

Jim Davis- Hide quoted text -

- Show quoted text -


The only way any of that would make sense is if the cost of returning
workers to Earth, and the related turnover, was less than the cost of
constructing a habitat. Slot in selected assumptions about relative
cost and you can reach an answer. The answer is almost surely going
to be 'no'.



What this all reminds me of is the Shuttle/ISS argument:
"What can the Shuttle do, now that its military and commercial missions
have been canceled?"
"It can build a Space Station!"
"What purpose will the Space Station serve?"
"It will give the Shuttle something to build!" :-)

Pat
  #286  
Old October 24th 07, 09:21 PM posted to rec.arts.sf.science,sci.space.history
Hop David
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Posts: 656
Default Questions about "The High Frontier"

Pat Flannery wrote:



What this all reminds me of is the Shuttle/ISS argument:
"What can the Shuttle do, now that its military and commercial missions
have been canceled?"
"It can build a Space Station!"
"What purpose will the Space Station serve?"
"It will give the Shuttle something to build!" :-)

Pat


Except there's nothing in LEO.

Ferdinand III of Castille would've been correct if he had pointed out
there's nothing in the middle of the Atlantic Ocean worth the expense of
building and sending carracks.

Evidently Isabella didn't subscribe to that argument.

Hop
  #287  
Old October 24th 07, 09:38 PM posted to rec.arts.sf.science,sci.space.history
Hop David
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Posts: 656
Default Questions about "The High Frontier"

Johnny1a wrote:

On Oct 23, 9:16 am, Hop David wrote:


While CCs may be poor in some those materials, there are other asteroids
that aren't.

I acknowledge that one asteroid containing all these resources would be
rare. It would be hard for colonists on a metallic asteroid to use
nitrogen from an NEO on a different orbit.

On the other hand, there's no superhighways, oceans or rivers that can
be used for transportation on Mars. Transportation will be a substantial
barrier to self sufficiency on Mars as well as among the NEOs.



But once an initial presence is established on Mars, i.e. a
functioning town or other colony, constructing such (superhighways or
the equivalent) is a relatively straightforward project, in comparison
to establishing a viable interplanetary transport system between the
asteroids.


Given backhoes, bulldozers & other heavy equipment, sure. Mars won't
have the manufacturing infra structure to make a fleet of these any time
soon. What finances sustaining and developing Martian settlements until
they become self sufficient? I wouldn't rely on U.S. tax payers,
political climate changes and leadership changes too frequently for the
sustained prolonged effort that would be needed.

Exports from the Moon, Phobos, Deimos and NEOs are a long shot, granted.
But they're more plausible than exports from Mars.

Hop
  #288  
Old October 24th 07, 09:50 PM posted to rec.arts.sf.science,sci.space.history
Pat Flannery
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Posts: 18,465
Default Questions about "The High Frontier"



Johnny1a wrote:
Population growth rates aren't controlled by the availability of birth
control. In fact, nobody knows what determines population growth and
decrease rates once the basic necessities of life are covered, they
seem to follow a logic of their own.


One problem they had with birth control in the third world (besides
religious taboos, and macho issues) was that a lot of the people
couldn't understand that the principle the condom worked on was (there's
actually one culture I read about somewhere out there that recognizes no
connection between sex and pregnancy. Women get pregnant when the gods
deem they should get pregnant, and if a husband is away from his wife
for a year and comes back to find her nursing a baby...well, that was
just her time to get pregnant, that's all). :-)
In one village in Africa, a family planning nurse demonstrated how the
condom was to be used by putting it over the end of a broom handle; on
her next visit, she noted that the villagers were now convinced that the
birth rate was going to drop as every broom handle in the village now
had a condom on it.
Considering the number of unwanted pregnancies that occur here in the
U.S. even nowadays, I suspect that easily available, reliable and low
priced birth control worldwide would lead to a major decline in
birthrate to below replacement levels, especially in non-sustenance
agrarian societies - as that is one of the few areas where a large
family is a asset, as many children means many workers to till the land.
Even here in North Dakota average farm family size is far lower since
the advent of advanced farm machinery, as back in the 1930's farm
families with ten or more children were not uncommon. I even knew a farm
girl born in the late 1950's who had eleven brothers and sisters.

Pat


  #289  
Old October 24th 07, 09:57 PM posted to rec.arts.sf.science,sci.space.history
Hop David
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Posts: 656
Default Questions about "The High Frontier"

Johnny1a wrote:

On Oct 23, 5:58 pm, Jim Davis wrote:


Mike, you're a good guy and everything, but the above is a textbook
example of thinking with your heart instead of your head. In any
other context except space (you yourself bring up oil rigs) you
would quickly recognize the absurdities. But since this is space
we're talking about...well, things are different in space, right?

Jim Davis- Hide quoted text -

- Show quoted text -



The only way any of that would make sense is if the cost of returning
workers to Earth, and the related turnover, was less than the cost of
constructing a habitat. Slot in selected assumptions about relative
cost and you can reach an answer. The answer is almost surely going
to be 'no'.


Slot in selected assumptions? You're leaving yourself wide open there.

Bigelow Aerospace hopes to rent their habs at these rates:
4 weeks $15 million
8 weeks $18 million
1 year $88 million
http://en.wikipedia.org/wiki/Bigelow_Aerospace

A shuttle mission to carry workers would probably cost $450 million or
more per round trip.
http://www.nasa.gov/centers/kennedy/...uttle_faq.html

These are just two selected assumptions from a multitude of possible
scenarios. The Shuttle doesn't have to be the last word in
transportation costs and there's a very wide spectrum of habs between
Bigelow and O'Neill.

Your conclusion that the answer is "almost surely going to be no" needs
more back up before I accept it.

Hop

  #290  
Old October 24th 07, 10:29 PM posted to rec.arts.sf.science,sci.space.history
Pat Flannery
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Posts: 18,465
Default Questions about "The High Frontier"



Hop David wrote:
"What can the Shuttle do, now that its military and commercial
missions have been canceled?"
"It can build a Space Station!"
"What purpose will the Space Station serve?"
"It will give the Shuttle something to build!" :-)


Except there's nothing in LEO.

Ferdinand III of Castille would've been correct if he had pointed out
there's nothing in the middle of the Atlantic Ocean worth the expense
of building and sending carracks.

Evidently Isabella didn't subscribe to that argument.


They didn't build anything for Columbus's voyage; all three ships
already existed from Spain's already large merchant fleet doing business
with the Indies, and they wanted a way there that was shorter and didn't
have to deal with Muslim middleman for the spices and what-not they were
getting from Asia.
Even then the ships they gave Columbus were anything but top-notch, so
they wouldn't be any great loss if they sailed off never to be seen again.
It would have barely shown up on Spain's annual expenditures for 1492.
Now, if you could do space exploration on a budget like that... say,
grab a 1970's era 747, and a couple of fairly beat-up 1980's 737's and
fly them to Mars or the asteroid belt, more power to you.
Whereas colonization of North America panned out...though not for the
Spanish in the long run...South America had too much jungle in its
northern half, and Australia proved to be a huge wasteland that you
could only inhabit the coastlines of.
Yet either of those places were far, far, more amiable for habitation
than the Moon, Mars, or the asteroids.
As I pointed out before, you could start building cities in Antarctica
in conditions more pleasant than Mars; you can breath the air, and water
is already proven to be plentiful. There's bound to be minerals of one
sort or another, transportation to and from the place is fairly quick
and low cost, and assuming you like a diet high in meat rather than
vegetables, the seas surrounding its coast will provide it in abundance.
But you don't see cities springing up all over it or in the Australian
outback (even Brazil pretty much admitted Brasilia was a flop of an
idea), and that doesn't bode any too well for places that are even more
uncomfortable in regards to climate. Say ones lacking breathable air and
getting sprayed with the solar wind.

Pat
 




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