Questions about "The High Frontier"

Hop David wrote:

Mike had said transportation and turnover costs can justify
construction of better worker housing.

No. Mike said transportation and turnover costs can justify
construction of better worker housing in *space*.

You labeled his notion
absurd and asked him why should space be different from the
earth. Upthread it was _you_ who was equating earth and space.

Right. I equated an uninhabitable place in space with other
uninhabitable places on *earth*. Mike understood this. You apparently
don't.

My reply was that on earth, as well as in space, transportation
and turnover costs can exceed costs of better worker housing.

And you provided an example on earth (Ajo, Arizona) but not space.
And I replied that comparing habitable places with unihabitable
places is not convincing.

Jim Davis

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.

2.) We're discussing places that are uninhabitable, whether on
earth or in space.

What's so absurd
about this notion?

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. But
instead we have a normally sane and sober individual trying to
argue in effect that if transportation costs can be kept *high*
enough space settlement might make economic sense!

Jim Davis

Hop David wrote:

Hotel rooms vs subway cars? Do you imagine transportation costs
to and from orbit will be the same as a subway ticket?

No. I can't imagine how you think I might, either.

The shuttle or any plausible orbital transportation is not even
remotely close to a subway car.

Nor are the shuttle or any plausible orbital transportation remotely
close to a permanent settlement either. Thus my amazement that you
brought it up.

Jim Davis

On Tue, 30 Oct 2007 17:51:29 -0700, Hop David wrote:

John Schilling wrote:

Water, you can get, though only bound up in a mass of carbonaceous
non-volatiles that bears a strong resemblence to coal. And you've
got to be pretty desperate to try and squeeze water from a lump of
coal. But it's at least within the bounds of reason and plausibilty.

Actually, some people here on Earth are trying to squeeze water from
coal; mainly to improve the coal's energy yield but also, in arid
regions like Australia, to reuse the water. (I'd guess that the best
use of water wrung/evaporated from coal is to recycle it into slurry
pipelines, an application where you don't have to worry about
detoxifying the water.)

As for the idea that being 1 AU out from the Sun precludes embedded
water ice, we shouldn't be so sure. The very notion of ablative
reentry was substantially inspired by the discovery that meteorites
landed with cold interiors. How cold can they get?

According to rough calculations here

http://www.meteorobs.org/maillist/msg20222.html

perhaps as low as -25 C.

OK, fine. Of course, a one-kilometer sphere of water ice, in vacuum
and maintained at a temperature of -25C, will sublimate away entirely
in about thirty days. So why were you considering that to be a "low"
temperature again?

I'm not sure where Ed Majden of the meteorobs.org mailist got -25C (for
earth sans atmosphere), -21C light silicate, 5 C carbonaceous, and 93 C
for an iron meteorite. Different a/e ratios?

Yep. Bare metals in particular get nice and toasty in space, on account
of differential a/e between solar and thermal-IR spectra.


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.

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.


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.

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).


--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
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* for success" *
*661-951-9107 or 661-275-6795 * -58th Rule of Acquisition *

Jim Davis wrote:


You labeled his notion
absurd and asked him why should space be different from the
earth. Upthread it was _you_ who was equating earth and space.


Right. I equated an uninhabitable place in space with other
uninhabitable places on *earth*. Mike understood this. You apparently
don't.

Oil rigs are uninhabitable places generally not far from shore.
Transportation costs from rig to shore is low. For this reason the
comparison is utterly absurd.

Mike has repeatedly pointed this out and it repeatedly sails over your head.




My reply was that on earth, as well as in space, transportation
and turnover costs can exceed costs of better worker housing.


And you provided an example on earth (Ajo, Arizona) but not space.

I have provided an example of space transportation. A shuttle trip _to
LEO_ costs $450 million. Comparing this to a subway ride is completely
and utterly absurd.

Hop

Hop David wrote:
Hop David wrote:


So if you want to make a terrestial transportation vs habs metaphor,
Lear Jet vs trailer home is more apt.

Make that a Lear Jet with all the space and comfort of a coffin vs
trailer home.

If you want to see a real coffin in space, check this thing out -
http://www.astronautix.com/craft/1crgterm.htm
Spending a year flying from Mars to Earth in something around the size
of a large refrigerator.

Pat

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. But
instead we have a normally sane and sober individual trying to
argue in effect that if transportation costs can be kept *high*
enough space settlement might make economic sense!


I still think if this happens it will be almost entirely automated...you
save a huge amount in total mass that needs to be launched, need zero
life support on a ongoing basis, and remove the need to transport people
to and from the mining destination.
If you want to build a L colony, you let the robots build it down to the
last blade of grass, then just move the people in after it's ready to go.
I don't know why they would want to live there, maybe it has low taxes
or legalized zero g prostitution with sex-robs....strange green-haired
androids with eyes the size of baseballs, beak-like noses, and mouths so
tiny that they'd have a hard time sucking their little fingers, much
less anything else. 'All-your-orgasms-are-belong-to-us' they would
girlishly coo in high pitched Japanese accents, then begin giggling as
their cheeks turned bright day-glow red, and a strange blue-white glow
that emits lightning bolts emanates from their crotches. ;-)

Pat

Mike Combs wrote:

I outlined the scenario of workers moving from small aluminum cylinders
comparable to ISS modules to the Stanford Torus (or Bernal Sphere). You
insist that they will live on Earth with a spouse, raise children on Earth,
and periodically commute to space. Some of us expect space workers to be
living in space, at least for a few years duration at a time (and after
radiation shielding and spin gravity are implemented).


A space habitat is going to be a pretty experience limiting place to
raise young children.
Around 90 percent of the biosphere that a kid might run into in even a
inner city won't be there.
Rats for instance, and cockroaches.
Seriously, you could raise a kid in a environment like that and have
them come down with a very severe panic attack the first time they hit
Earthside, 50 percent of what's around them is the empty sky, and the
horizon goes down rather than up...like it's supposed to.
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.
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.
It's rather like Spain setting off on voyages of discovery by inviting
people to live on huge ships anchored in mid-Atlantic for years at a
time, or getting to America....where they can live in caves and drink pee.
You're going to need very good pay indeed, or a black-jack equipped
press gang to round them up and drag them to the rocketship. :-D

Pat

"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.

--


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

"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.

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.

--


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