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Questions about "The High Frontier"



 
 
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  #291  
Old October 24th 07, 10:55 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:

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


And we hoped to launch payloads on the Shuttle at around $118.00 per pound.
When Bigelow gets a habitat in orbit and people start renting it, then
we'll see what the price is, and how many customers are lining up.

Pat

  #292  
Old October 24th 07, 10:56 PM posted to rec.arts.sf.science,sci.space.history
Quadibloc
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Default Questions about "The High Frontier"

On Oct 23, 12:02 pm, "Mike Combs"
wrote:
There seems to be an assumption that overland travel on Mars has got to be
easier than moving between asteroids because the latter is space travel and
the former isn't, and as everybody knows, space travel is difficult,
dangerous, and hideously expensive. I think this notion overlooks two
points:

1. Overland travel on Mars, unlike same on Earth, will have pressurization
and other life-support requirements little different from space travel.

2. Our notions of space travel are influenced by our most common experience
of it, which is to say, travel from the surface of the Earth into orbit.
Such travel requires large amounts of thrust (greatly in excess of vehicle
weight in 1-G) quickly achieved, and an aerodynamic shape. None of these
will be requirements for systems traveling from one asteroid to another.


These are legitimate points. If one is _in_ space, one doesn't need an
awful lot of thrust to go places.

However, while a Mars buggy needs to be pressurized, a voyage from one
asteroid to another, if it is to have modest fuel requirements, will
take a while. Trips between the Kuiper Belt for biomass and the
Asteroid Belt for metals will take many years.

So, while you are right that the commonplace view based on past
experience of an Apollo moon mission versus a drive to the country in
one's car exaggerates the situation, Mars is a single body that has
both metals and carbon, hydrogen, oxygen, and nitrogen available. So I
think it is still favored for lower start-up costs despite the fact
that the disparity can be exaggerated.

John Savard

  #293  
Old October 24th 07, 11:48 PM posted to rec.arts.sf.science,sci.space.history
Hop David
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Default Questions about "The High Frontier"

Pat Flannery wrote:


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;


You're ignoring some of my points. There's nothing in LEO. Just as, from
Ferdinand III's point of view, there was nothing in the middle of the
Atlantic.

There were no Carracks in the time of Ferdinand III. And the resources
of the mid-Atlantic would not have justified the development and
building of Carracks.

Again, pointing out that LEO is a dead end is not an argument that we
shouldn't bother to build our spacefaring capabilities.


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.


I've mentioned Mars and the asteroid belt as possibilities only after
other intermediate steps are accomplished.

Skipping these steps would be like sending the Santa Maria straight to
Sutter's Mill.

And on his first voyage, Columbus did little more than bring back
information. It was more comparable to the Clementime Mission and other
Discovery missions around our neighborhood in the solar system.

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.


http://www.globalwarmingart.com/imag...from_Space.jpg
I can see the growing corridor between Tucson and Phoenix near where I
live. These cities are expanding and fusing into a single huge
megapolis. Driving to Phoenix, I can see many formerly uninhabited
regions that are now row after row of houses. Who's to say what this
picture will look like 100 years from now?

And again, I don't see space development as an escape valve for mounting
population pressures. I see it as a way to increase options.

Hop
  #294  
Old October 25th 07, 12:10 AM posted to rec.arts.sf.science,sci.space.history
Hop David
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Posts: 656
Default Questions about "The High Frontier"

Quadibloc wrote:

On Oct 23, 12:02 pm, "Mike Combs"
wrote:

There seems to be an assumption that overland travel on Mars has got to be
easier than moving between asteroids because the latter is space travel and
the former isn't, and as everybody knows, space travel is difficult,
dangerous, and hideously expensive. I think this notion overlooks two
points:

1. Overland travel on Mars, unlike same on Earth, will have pressurization
and other life-support requirements little different from space travel.

2. Our notions of space travel are influenced by our most common experience
of it, which is to say, travel from the surface of the Earth into orbit.
Such travel requires large amounts of thrust (greatly in excess of vehicle
weight in 1-G) quickly achieved, and an aerodynamic shape. None of these
will be requirements for systems traveling from one asteroid to another.



These are legitimate points. If one is _in_ space, one doesn't need an
awful lot of thrust to go places.

However, while a Mars buggy needs to be pressurized, a voyage from one
asteroid to another, if it is to have modest fuel requirements, will
take a while. Trips between the Kuiper Belt for biomass and the
Asteroid Belt for metals will take many years.


Trips to the Kuiper belt for biomass are unnecessary, in my opinion.
http://clowder.net/hop/railroad/asteroidresources.html

Nor are trips to the asteroid belt. I suspect both metallic asteroids
and asteroids with ice interiors exist among the NEOs.


So, while you are right that the commonplace view based on past
experience of an Apollo moon mission versus a drive to the country in
one's car exaggerates the situation, Mars is a single body that has
both metals and carbon, hydrogen, oxygen, and nitrogen available. So I
think it is still favored for lower start-up costs despite the fact
that the disparity can be exaggerated.


And what would the return on investment for martian start up costs be? I
can imagine profitable exports from the Moon, Phobos, Deimos or NEOs to
near earth space. These may be unlikely but profitable Martian exports
are far more unlikely.

Hop
  #295  
Old October 25th 07, 12:45 AM posted to rec.arts.sf.science,sci.space.history
Michael Ash
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Posts: 128
Default Questions about "The High Frontier"

In rec.arts.sf.science Pat Flannery wrote:
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). :-)


These perceptions can be changed in time, though.

A perhaps greater problem is that children are the only form of social
security and retirement planning that exists in many countries, and these
countries tend to have high child mortality rates as well. If you want to
be highly confident of having enough children around to take care of you
when you're old and your children have a fair chance of dying first, you
need to have a *lot* of them. And of course most of the time most of them
live and you have a lot more than needed. Hence, population explosion.

In first world countries you can be very comfortable in your old age with
no children at all with good retirement planning, and if there's a good
social security system you don't even need that, so the number of children
you need to have to ensure a comfortable old age drops to zero.

There's a looming crisis now in the first world countries in the form of
the rapidly aging population and the rapidly increasing health care costs
which go with it. This will no doubt be manageable, but largely because
the first world countries have lots of economic output with which to
manage it. Foisting this problem on poor countries without first
addressing the problem of them being poor seems like putting the cart
before the horse to me.

--
Michael Ash
Rogue Amoeba Software
  #296  
Old October 25th 07, 01:42 AM 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:


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



And we hoped to launch payloads on the Shuttle at around $118.00 per pound.
When Bigelow gets a habitat in orbit and people start renting it, then
we'll see what the price is, and how many customers are lining up.

Pat


You snipped a lot of context. I was arguing against the notion that
worker transportation costs would surely not justify hab construction.

Even given more pessimistic hab costs and more optimistic transportation
costs (the website you snipped said $450 million per shuttle trip),
transportation expense could justify construction of habs.

Hop
  #297  
Old October 25th 07, 01:51 AM 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:


There were no Carracks in the time of Ferdinand III. And the resources
of the mid-Atlantic would not have justified the development and
building of Carracks.


As to carracks, there were indeed carracks around in the 15th century...
in fact, I hate to do this... but the Santa Maria was a carrack:
http://en.wikipedia.org/wiki/Carrack
http://en.wikipedia.org/wiki/Santa_M...ADa_%28ship%29

http://www.globalwarmingart.com/imag...from_Space.jpg
I can see the growing corridor between Tucson and Phoenix near where I
live. These cities are expanding and fusing into a single huge
megapolis. Driving to Phoenix, I can see many formerly uninhabited
regions that are now row after row of houses. Who's to say what this
picture will look like 100 years from now?


So we build a highway and rail link to the Moon and Mars? That's been
suggested befo
http://www.vanishingbooks.com/featur...omearthfxd.jpg

Pat
  #298  
Old October 25th 07, 01:54 AM posted to rec.arts.sf.science,sci.space.history
John Schilling
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Posts: 391
Default Questions about "The High Frontier"

On Mon, 22 Oct 2007 13:09:20 -0500, "Mike Combs"
wrote:

"Bryan Derksen" wrote in message
news:E8SSi.105062$th2.51759@pd7urf3no...

Seems like a lot of extra expense moving an entire asteroid to L5 before
mining volatiles out of it when one could mine the volatiles on-site and
ship just those back.


Then there's one idea that I like: If you're using a mass-driver as your
reaction engine, the beauty of it is that you can use literally anything for
reaction mass. So maybe you start materials processing on the way home, and
use the dross for reaction mass. Then by the time you get home, what's left
is the high-dollar materials.


You know, for someone who just one post ago was proclaiming how energy was
and always will be the dominant factor in space operations, you're awfully
free with the gigawatts here.

Because even a measly hundred-meter asteroid, delivered to L5 using the
mass-driver approach you describe, is going to require a gigawatt or so
of continuous electric power for several years.

No doubt you are going to just wave your hands and say, "in space,
sunlight is free!".

Solar power generation equipment is *not* free, and I'm pretty sure that
whoever winds up actually paying the bills, is just going to go and bring
back whatever asteroidal materials they actually need, when they need
them. Not entire asteroids, just becacuse it would be nifty to have
one close at hand.


--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
* for success" *
*661-951-9107 or 661-275-6795 * -58th Rule of Acquisition *
  #299  
Old October 25th 07, 01:54 AM posted to rec.arts.sf.science,sci.space.history
John Schilling
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Posts: 391
Default Questions about "The High Frontier"

On Tue, 23 Oct 2007 08:26:08 -0700, Hop David wrote:

Michael Turner wrote:


I don't think hysteria is the right word. Large payloads would be harder
to control and a tiny error could change aerobraking to lithobraking. I
would call it "Deep Impact sensible fear". Again, I advocate payload
mass ceilings well below Tunguska size.


I'm still curious whether there might be a way to increase payload
mass and reduce terrestrial hazards by delivering asteroid-derived
payloads to Earth orbit in the form of large spherical shells of
material. As I've probably mentioned in this forum before, I was once
asked to look at an RFP for "demisable tanks" -- i.e., satellite fuel
tanks guaranteed to burn up on reentry. That inquiry went nowhere,
AFAIK. Which underscores a point: maybe you don't need ablative
shielding or heat-soaking tiles to bring stuff down intact. After
all, LEO satellite fuel tanks have been found in desert regions with
little more than scorch marks and dents from hitting the ground (at a
relatively low terminal velocity, obviously.) Maybe that's a bug for
satellite fuel tanks, but it's arguably a feature if you're interested
in aerobraking or aerocapture of resources delivered from cislunar or
interplanetary space.


Now let's say you want to deliver a lot of asteroid-mined metal to an
L-point, using aerobraking in the Earth's atmosphere. Blow the metal
up into a big, relatively thin-walled sphere. Maybe store some
asteroid-derived volatiles inside, which would coat the interior as
they freeze down to the point where you get into equilibrium with
sublimation losses.


Asteroid mined metal would come from a metallic asteroid which is
unlikely to have volatiles.


Actually, the stony chondrites are typically 10% metal or so, and metal
in a much more easily recovered form - the stuff can be magnetically
seperated from finely crushed rock, and there's reason to believe that
lots of stony chondrites have pre-crushed surfaces. If not, well, we
know how to make rock-crushers.

Metal asteroids, seem to be solid metal. Solid nickel steel, rather
like the stuff battleships used to be made out of. This poses certain
obvious problems for any wannabe asteroid-miner...


--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
* for success" *
*661-951-9107 or 661-275-6795 * -58th Rule of Acquisition *
  #300  
Old October 25th 07, 01:54 AM posted to rec.arts.sf.science,sci.space.history
John Schilling
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Posts: 391
Default Questions about "The High Frontier"

On Mon, 22 Oct 2007 12:56:53 -0500, "Mike Combs"
wrote:

"John Schilling" wrote in message
.. .

OK, let's see: How about useful concentrations of Helium, Lithium,
Beryllium, Boron, Nitrogen, Fluorine, Neon, Sodium, Aluminum, Chlorine,
Argon, Potassium, Titanium, Chromium, Manganese, Copper, Zinc, Arsenic,
Bromine, Krypton, Strontium, Zirconium, Niobium, Molybdenum, Silver, Tin,
Antimony, Iodine, Xenon, Barium, Hafnium, Tantalum, Tungsten, Gold,
Mercury, Lead, Bismuth, Thorium, and Uranium.


You may have a point here, although I would venture to say that we use minor
quantities of these materials in comparison to steel, glass, and concrete.
Perhaps asteroidal settlements will buy aluminum and titanium from lunar
colonies, who in turn will be interested in buying hydrogen, carbon, and
nitrogen from asteroid settlements.


What sort of asteroid were you imagining had useful concentrations of
Nitrogen, again?

And the Moon seems scarcely better, though it's at least different and
it's big enough that there's still room for surprises. Mostly, though,
both the Moon and the Asteroids are very boring, geologically speaking,
each rich in about half a dozen or so sorts of useful stuff and that's
about it.

For the full range of minerals you need to support a civilization, you
really want something with a more interesting geology.


Making them useful requires more than just keeping them spinning, as you
ought to know by now.


Yes, but the question we were dealing with was what is the extra expense of
having to provide your own gravity. So it's a valid point.


If all you want is gravity, you don't need to fly to an asteroid. If what
you want is gravity in a location that's conveniently placed to whatever
unique advantages the asteroid environment offers, you need to not only
*have* gravity, but you need a convenient way to get from where the
gravity is to where the asteroid is.

Unless your goal is to just watch the asteroid spin by your window every
minute or so, which seems pointless. Otherwise, making something spin
is the easy part. The interface between the spinning part and the rest
of the universe, is where it gets hard.


But the premise is false, because real-world economics are a whole lot
more complicated than that. Energy is rarely the dominant consideration.


It's currently the dominant consideration in space, and is likely to remain
so for the foreseeable future.


Energy is the dominant consideration in space?

Why is it that my copy of Larson & Wertz's "Space Mission Analysis and
Design", devotes only seventy-one of its nine hundred seventy pages, to
the chapters on power and propulsion systems?

Why is it that in ten years of work as a professional space mission
analyst, I have *never* had a customer say, "My spacecraft would work
best if it were in Orbit X, but it would take lots of energy to get
there so I'll settle for more accessible Orbit Y instead"?

Heck, why have none of them ever even said, "Hey, interesting idea,
I'll have to think about that" when I suggested Orbit Y myself?


Energy has *never* been the dominant consideration in space.

At least, not if you're talking about people who actually do stuff
with actual spacecraft. Imaginary spacecraft are a different matter,
obviously.


--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
* for success" *
*661-951-9107 or 661-275-6795 * -58th Rule of Acquisition *
 




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