Questions about "The High Frontier"

"Pat Flannery" wrote in message
...

A space habitat is going to be a pretty experience limiting place to raise
young children.

Nonsense. Just this morning I read an article about a young man who was
born in a North Korean forced-labor camp. He didn't even know the name of
the leader of his country, or the slightest detail about the outside world.
He had to watch his mother be executed by hanging, and his brother by being
shot. Why did his parents choose to have children in such a dismal setting?
They were permitted to marry and to have a 5 day "honeymoon" before being
separated. A child resulted. It's a very powerful instinct.

You could do holographic projections of a sky with clouds and birds in it
and add appropriate sounds, breezes, and smells...but making a ersatz
Earth in space when there's a real one around to live on seems pointless.

I would agree that the less fakery in a space habitat, the better. I don't
think space settlements should be simulations of the Earth, they should be
recreations.

There's no real good reason to live in a huge can in space or a desolate
lifeless world when you could be actually be living on a pretty nifty and
friendly planet instead, that has lots of junk food that wasn't made from
soy protein derived from plants grown in human crap and a cup of lemonade
that was inside someone's bladder yesterday.
Don't even get me stated to what happens to the bodies of the dead on the
space colony, and where the breakfast sausages come from.

But of course much the same kind of closed ecology exists here on Earth.
We're just less conscious of it because the loops are bigger.

You've certainly demonstrated that you're very imaginative in this thread.
But I don't think you've demonstrated that your imagination is a good guide
to future events.

--


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

On Thu, 1 Nov 2007 13:01:48 -0500, in a place far, far away, "Mike
Combs" made the phosphor on my
monitor glow in such a way as to indicate that:


You've certainly demonstrated that you're very imaginative in this thread.
But I don't think you've demonstrated that your imagination is a good guide
to future events.

I've never noticed that Pat's imagination is a good guide to much of
anything at all, other than amusement.

John Schilling wrote:

But I can see those temperatures are for objects in circular orbits 1 AU

from the sun.


An ordinary short period comet would have an aphelion greater than 1 AU.
It moves slower at aphelion and so would spend more time in the colder
regions of its orbit.


Given an NEO with an insulating mantle, a greater than 1 A.U. aphelion
and a 1 A.U. perihelion what would the temperature be beneath the mantle?


From page 13 of _Atmospheric Holes and Small Comets by L. A. Frank and
J. B Sigwarth:


[inside stays frosty through perihelion]

Yes; given any reasonable thickness of regolith, temperature variations
during an orbit will be confined to the surface layers. The interior will
remain at approximately orbit-average equilibrium conditions. Simplest
approximation is to treat the interior as if it were a body in a circular
orbit with the same semimajor axis as the actual body.

Here's a picture of orbital radii of an ellipse with e = sqrt(1/2).

http://clowder.net/hop/railroad/elli...ipseradii.html

"a" in the top graph is the semimajor axis.

This seems to indicate the object would spend more time at distances a
than closer to the sun.

So, given two similar objects, one in elliptical orbit, the other
circular, ellipse semi-major axis = circle radius, I'd expect the object
in the elliptical orbit to have a cooler interior.


For long-term survival of an iceteroid, you're going to need a semimajor
axis of 1.5-2.0 AU; at least as far out as Mars and probably at least as
hard to get to/from.

Given that eccentric orbits seem more prone to healthy inclinations, I
would agree with that.




Somewhat more important is any layer of dusty regolith overlaying the
ice. However, even half a kilometer of regolith with 10% porosity
and ten-micron pore size only gets you about 350,000 years lifetime,
which doesn't add up to a hill of beans on an astronomical timescale.
So you really are going to want to cool things down just a tad more,
I think.


I was surprised to learn of a substantial change to Tempel 1's orbit in
the last 100 years. I was amazed to see in my lifetime Shoemaker Levy's
collision with Jupiter. These lead me to believe substantial orbit
changes are common. I'm not sure how rare the very recent arrivals are.
So an NEO that's only been in our neighborhood 350,000 years isn't out
of the question, in my opinion.


Per Lewis in "Mining the Sky: Resources of Near-Earth Space", the usual
evolutionary path for a NEO takes ~100E6 years, though there is a rare
"fast path" that only takes ~1E6 years. 350,000 is pushing it. And to
have useful ammounts of ice still remaining in a body less ideal than
the thought-experiment version above, you need to get hold of it rather
sooner than that.



And also I'm guessing the 350,000 year figure is based on an object with
a circular 1 A.U. orbit, which would be different than most NEOs.

Was I correct in believing your 350,000 year figure is based on a 1 A.U.
circular orbit? Eccentric orbits with greater semi major axis might last
more appreciable fractions of the evolutionary paths Lewis mentions.

I might be able to model circular orbits if I knew the a/e of cometary
mantles (I can't seem to find guesstimates in the papers I've found).
But elliptical orbit models are still a mystery to me. Also I don't know
how to get mass loss rates due to sublimation.

I'd like to be able to model iceteroid lifespans in various orbits. One
of my favorite orbits has an semi major axis of 1.31 A.U. and
eccentricity of .24.




Also, the ice we're mostly concerned with here is ammonia.


Aren't there other nitrogen compounds common to comets that have a
higher freezing point than ammonia?


Only at fractional-percent levels, and even those still somewhat
volatile and will thus deplete somewhat over a megayear or so.
Nitrogen is notoriously hard to bind into anything really stable;
the only really good sources are likely to be atmospheres (where
the tendency of just about every *other* gas to react with something
solid, leaves nitrogen preferentially enhanced).

Well, then the availability of nitrogen on Mars is a good argument in
Mars' favor.

Hop

Mike Combs wrote:
"Pat Flannery" wrote in message
...

A space habitat is going to be a pretty experience limiting place to raise
young children.


Nonsense. Just this morning I read an article about a young man who was
born in a North Korean forced-labor camp. He didn't even know the name of
the leader of his country, or the slightest detail about the outside world.
He had to watch his mother be executed by hanging, and his brother by being
shot. Why did his parents choose to have children in such a dismal setting?
They were permitted to marry and to have a 5 day "honeymoon" before being
separated. A child resulted. It's a very powerful instinct.


What exactly the relationship of a child born in a prison camp i what is
probably the most ruthless nation on the face of the Earth has to do
with voluntarily liing on a space colony is beyond me.
I note their are not many children living on oil platforms or Antarctic
science stations, both environments that somewhat resemble a space
colony due to their isolation on a day-to-day basis from mainstream
civilization, particularly in regards to the science station.


You could do holographic projections of a sky with clouds and birds in it
and add appropriate sounds, breezes, and smells...but making a ersatz
Earth in space when there's a real one around to live on seems pointless.


I would agree that the less fakery in a space habitat, the better. I don't
think space settlements should be simulations of the Earth, they should be
recreations.


As long as we're on this subject, I was wondering about something in
regards to the ecology of things living on the space colony. What
screwed up the Biosphere 2 experiment was the aerobic bacteria getting
out of control, and screwing up the oxygen balance. How exactly are you
going to control the conditions inside the space colony to the point
where a new person arriving from Earth doesn't bring along something
microscopic, either on them or in them, that gets loose on the habitat
and screws up the ecology of it....the flip side is also
important...with only a very limited exposure to a diverse set of
microscopic flora and fauna, the inhabitants of the colony may never
develop a resistance to numerous microorganisms, and find themselves as
vulnerable as H.G. Wells' Martians if they ever visit Earth.
In fact, the Biosphere 2 was a the closet simulation of the ecology and
social dynamics of a space colony ever done on Earth, and it was a
complete disaster area in both regards, with the inhabitants breaking
down into two opposed groups, oxygen needing to be added, and the crops
not producing sufficient food for the test inhabitants.
At least they had the option of leaving if things went bad enough; on a
space colony, abandoning it means the inhabitants must be sent somewhere
else, and if you are out in the asteroid belt doing mining operations,
the only logical place from a time and energy point of view is other
space colonies. T increased population due to the new immigrants would
then screw up their ecology also.


There's no real good reason to live in a huge can in space or a desolate
lifeless world when you could be actually be living on a pretty nifty and
friendly planet instead, that has lots of junk food that wasn't made from
soy protein derived from plants grown in human crap and a cup of lemonade
that was inside someone's bladder yesterday.
Don't even get me stated to what happens to the bodies of the dead on the
space colony, and where the breakfast sausages come from.


But of course much the same kind of closed ecology exists here on Earth.
We're just less conscious of it because the loops are bigger.


Psychology is a important aspect to things. Even though the water
recycled from urine and humidity from sweat on the ISS is perfectly safe
to drink, people don't drink it, but rather use it for washing themselves.

You've certainly demonstrated that you're very imaginative in this thread.
But I don't think you've demonstrated that your imagination is a good guide
to future events.


There are so many variables in the future that trying to predict it
accurately is almost impossible, as reading a lot of science fiction
from the past shows...it ended up a lot stranger than many authors
expected, even those writing in the 1950's.
One thing does hold true though; people tent to migrate toward areas
where conditions are more comfortable, less labor is needed to survive,
there is room for social interaction but not excessive crowding, and
varied food is more plentiful.
Space colonies may lack some of those.
The big problem economically is that it is virtually impossible due to
Earth's gravity well to manufacture goods in space that can't be
acquired on Earth more cheaply, with the possible exception of SPS and
sending the energy down via microwaves...and that means the goods made
in space have to be used in space.
The colonization of the New World was done with the specific intention
of shipping goods of to the Old World from it to generate a profit for
investors in it, whether it be gold, silver, and jewels, or tobacco and rum.
Take the ability to ship things back to make a profit for the investors
out of the equation, and North and South America may never have been
settled. by Europeans.
Once there is a large enough population living there, then a economy can
develop based on supplying the internal needs of that population...but
on the space colonies there isn't any real impetus to get the ball
rolling economically or population-wise, because all the products they
will make can be acquired far more cheaply cheaper on Earth; so your
left with the only people who want to go out there being zealots who
want to build the New Jerusalem somewhere out in space, untouched by the
baseness of Earth. For starters they aren't going to have the economic
resources to do that on there own, because the scale of this type of
project is something that's a challenge to a major first world nation,
which is why we don't have Brazilian space stations in orbit at the
moment. The only way they could get that scale of resources is to show
that the money is a investment that would generate a profit in a
reasonable period of time....and more importantly, generate a larger
profit in a reasonable period of time by this use than if it were
invested in some other enterprise.
.....and that's going to be a very tough nut to crack.

Pat

In article ,
Mike Combs wrote:
"Jim Davis" wrote

The absurdity comes in when logic that is accepted in one context
is rejected in another. Mike, you, and I recognize that on *earth*
uninhabitable places are not settled because it would be
fantastically expensive to do so, regardless of transportation
costs. This logic *should* apply to space settlements as well.

I think the one thing the kind of places you're thinking about have in
common is that there are currently no economic opportunities to exploit. If
such opportunities present themselves, places previous generations might
have declared "uninhabitable" become steadily more so over time, until later
generations see nothing so unusual about the idea of living in such a dismal
place because steady economic development (and technological advance) has
made it considerably less dismal.

I think the problem with this argument is Siberia; economic
development and technological advance has not made Yakutsk any more
habitable, and people with the choice of staying in Yakutsk and being
diamond-miners, or leaving Yakutsk for whatever work's available in,
say, the big city of Irkutsk, have tended to leave.

With the focussed resources of the Soviet Union, and the Soviet
Union's restrictions on movement, it was possible to make Yakutsk just
about livable.

There's no shortage of valuable materials to extract in the environs
of Yakutsk, but if you wish to build a processing plant then almost
anywhere further south or further west is more viable.

Tom

Thomas Womack wrote:

I think the problem with this argument is Siberia; economic
development and technological advance has not made Yakutsk any more
habitable, and people with the choice of staying in Yakutsk and being
diamond-miners, or leaving Yakutsk for whatever work's available in,
say, the big city of Irkutsk, have tended to leave.

Which causes serious problems for any invader stabilizing an eastern
front, as any kid who's played Risk would know :-).

--
Erik Max Francis && && http://www.alcyone.com/max/
San Jose, CA, USA && 37 20 N 121 53 W && AIM, Y!M erikmaxfrancis
Well there's too much living / And not enough life
-- Nik Kershaw

Jim Davis wrote:
Hop David wrote:


Upthread you wrote "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?"

In space as well as on earth, transportation costs can exceed
costs of constructing better worker facilities.


Two points:

1.) We're not merely discussing "better worker facilities". We're
discussing permanent settlement.

Hab improvement can be incremental. A possible path to permanent settlement:

1st generation: small, spartan habs.

2nd generation: slightly larger habs connected in pairs by rigid tunnels
(what I call batons). These would still be spartan, but slightly roomier
and providing centrifugal acceleration to maintain health.

3rd generation: a series of batons joined together to form a torus. This
also makes economic sense since a torus has a better volume to surface
area ratio than batons.

4th generation: Enlargements of existing tori (increasing livable space
and further improving volume to surface area ratio).

With huge transportation costs, any investment that enables lengthier
worker stays has potential ROI. As space infra structure accumulates,
costs of building better habs will fall. Over time the habs will reach a
level of quality enabling permanent settlement.

The absurdity comes in when logic that is accepted in one context
is rejected in another. Mike, you, and I recognize that on *earth*
uninhabitable places are not settled because it would be
fantastically expensive to do so, regardless of transportation
costs.

http://www.ghosttowns.com/states/az/fortuna.html
Prior to a pump and water line, this region was uninhabitable to either
Europeans or Native Americans. I don't believe the saloon keepers or
hotelier commuted to their work place - they were settlers. Had the
Fortuna ore body been as rich as the Ajo ore body, I believe it would
have been surrounded by homes occupied by families.

You point to oil rigs and ask why don't they have permanent homes for
families. Well, if helicopter rides to the shore cost $500,000,000 (or
even $5,000,000), the two weeks on - two weeks off shifts would not be
workable. The oil companies would have a much larger incentive to build
permanent homes onto the rig.

Given high transportation costs and a long lasting resource valuable
enough to enable ROI, a desolate region _can_ be settled.

Hop

On Fri, 02 Nov 2007 10:47:09 -0700, Hop David wrote:

John Schilling wrote:

But I can see those temperatures are for objects in circular orbits 1 AU

from the sun.


An ordinary short period comet would have an aphelion greater than 1 AU.
It moves slower at aphelion and so would spend more time in the colder
regions of its orbit.


Given an NEO with an insulating mantle, a greater than 1 A.U. aphelion
and a 1 A.U. perihelion what would the temperature be beneath the mantle?


From page 13 of _Atmospheric Holes and Small Comets by L. A. Frank and
J. B Sigwarth:


[inside stays frosty through perihelion]

Yes; given any reasonable thickness of regolith, temperature variations
during an orbit will be confined to the surface layers. The interior will
remain at approximately orbit-average equilibrium conditions. Simplest
approximation is to treat the interior as if it were a body in a circular
orbit with the same semimajor axis as the actual body.

Here's a picture of orbital radii of an ellipse with e = sqrt(1/2).

http://clowder.net/hop/railroad/elli...ipseradii.html

"a" in the top graph is the semimajor axis.

This seems to indicate the object would spend more time at distances a
than closer to the sun.

So, given two similar objects, one in elliptical orbit, the other
circular, ellipse semi-major axis = circle radius, I'd expect the object
in the elliptical orbit to have a cooler interior.

But temperature isn't linear with distance; the 1/R^2 attenuation of the
solar flux means the close-in period contributes disproportionately to the
energy balance. The two don't quite cancel, but I only get a 3.6% drop in
average temperature for your eccentricity of sqrt(1/2).

And a body that is either reasonably accessible from Earth, or any great
way along the evolutionary path from comet to asteroid, is going to have
an eccentricity rather less than 0.7


--
*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" *
*661-718-0955 or 661-275-6795 * -58th Rule of Acquisition *

On Thu, 1 Nov 2007 12:47:31 -0500, "Mike Combs"
wrote:

"John Schilling" wrote

For long-term survival of an iceteroid, you're going to need a semimajor
axis of 1.5-2.0 AU; at least as far out as Mars and probably at least as
hard to get to/from.

The former does not automatically lead to the latter.

It pretty much does.

The propulsive delta-V for a minimum-energy round trip between LEO and the
Martian surface, is 10.97 km/s. For a minimum-energy round trip between
LEO and an average 1.5-2.0 AU asteroid, it's 9.64 km/s.

Anyone who thinks that 12% reduction in delta-V means the asteroid is
significantly easier to get to, here's the rest of the story: The maximum
single-stage delta-V for the Mars round trip is 4.320 km/s; to get to the
asteroid and back you need to generate 4.675 km/s between opportunities to
refuel. And Mars is, by virtue of atmosphere and ice caps, a much easier
place to refuel - no heavy mining equipment required. Finally, with Mars
you get a chance for a repeat trip every 2.15 years at roughly the same
cost. For the asteroid, lining up the eccentricity and inclination for a
minimum-energy round trip is essentially a once-in-a-lifetime opportunity,
and the cost goes up if you want to go back at any other time.


Nitrogen is notoriously hard to bind into anything really stable;
the only really good sources are likely to be atmospheres (where
the tendency of just about every *other* gas to react with something
solid, leaves nitrogen preferentially enhanced).

That's good info. I need to remember that atmospheres may be of some
economic interest, if only for this reason.

Other advantages of atmospheres: whatever they do have in them, is much
much *much* easier to get at than anything bound up in solid form. On
the rare occasions when space-development activists run their plans for
lunar/martian/asteroidal resource extraction past actual professional
mining engineers, the result tends to involve a great deal of laughter,
and what few attempts have been made to even extract samples from those
environments have usually run into problems.

Pumping air, on the other hand, is pretty much foolproof. You have to
worry about dust, sometimes, but that's still much easier than mining.


Also, atmospheres are very handy things to have when it comes to slowing
down. And, in general, about half of space travel is about slowing down.
You really don't want to have to do that with rockets if you can possibly
avoid it.


--
*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" *
*661-718-0955 or 661-275-6795 * -58th Rule of Acquisition *

On Tue, 30 Oct 2007 12:22:17 -0500, "Mike Combs"
wrote:

"John Schilling" wrote in message
.. .

It's the workers you are rotating to and from Earth every month
or two where the week spent in transit is going to be a significant
loss, and where each worker has half a dozen opportunities every
year to say, "Screw it; I'm sick of living in a tin can and I've
made enough of a fortune already and I just found a girl I don't
want to leave quite yet, so I won't be back for the next tour."

We're viewing this similarly, save that I visualize tours of duty being
closer to 2 years than 2 months.

Even the military hasn't assigned two-year tours since World War II,
and that's without considering the adverse health effects of spending
two years at a time in a habitat without full radiation shielding and
gravity.

For two-year tours, you're going to need either a motivation on par
with Saving The World From The Forces of Darkness, conscription, or
living quarters where the staff will feel comfortable bringing (or
forming) their families.

More realistic figures would be the ~2-week tours on oil rigs, the
~6-week tours at arctic mining operations or on a supertanker crew,
or the ~90-day patrols of an SSBN. Even ISS does crew rotation every
six months or so, and that's with a staff out at the six-sigma level
of motivation.


--
*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" *
*661-718-0955 or 661-275-6795 * -58th Rule of Acquisition *