NASA Watch: "Bob Zubrin Steps In It Again"

In article ,
Thomas Lee Elifritz wrote:
James Nicoll wrote:

At this point in time, Earth is the richest known source of
fissionables, although it seems reasonable that Mars might also have
ore beds. Io is probably worth a close look, as well.

Sure, if you are interested in frozen mud, Mars has lots of it.


Mars has or had geological processes of the sort that
concentrated useful materials on Earth.


You'd be better off looking for meteorite fragments on Mars.

Meteors are not as far as I know particularly rich sources
of either uranium or thorium, If I recall correctly, any random
bit of granite has about 180x the uranium of a random meteor and
about 150x the thorium.

If some meteors have a lot of either uranium or thorium,
we'd probably be better off looking for the parent body in the
belt that they came from.
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wrote:

James Nicoll wrote:

In article . com,
wrote:

The inner solar system does not have the resources of the Kuiper Belt.


Oh, yes? Which resources do you have in mind?


Lighter elements, as you say, and a virtually non-existent gravity
well.

There are comets in the main belt.

http://www.ifa.hawaii.edu/~hsieh/mbc-release.html

The main belt is characterized as a bunch of rocks. But we really don't
know much about those asteroids. I would wager that a good number are
volatile rich.

As Paul Dietz mentioned, large outer Kuiper belt objects might be cold
enough and have enough gravity to hold He3.

Hop

Mike Combs wrote:
I'm almost ready to expect space mirrors the size of states before
fusion reactors.

And even if practical fusion reactors come along...a mirror the size
of a state is simply a sheet of aluminum. On Earth, yeah, that's *way*
impractical. But 100 AU out... it's a snap. Maintenance would be
relatively easy, either with robots or guys in suits. Of course, this
would be a low-g operation...

James Nicoll wrote:

In article ,
Hop David wrote:

James Nicoll wrote:


In article ,
Scott Lowther "scottlowtherAT ix DOT netcom DOT com" wrote:


John Savard wrote:



A spaceship going *to* the Kuiper Belt, or coming back from it,
certainly can rotate for artificial gravity.

Spaceships are largely short-term transportation systems, not permanent
homes.


A spaceship destined for the Kuiper doesn't seem likely to be short
term with any technology much below highly efficient [1] fusion. Take
MEDUSA: Vexhaust of perhaps 1000 km/s. Say we use a mass ratio of e^2 and
a total delta vee of 2,000 km: even with a high acceleration before
reaching the terminal velocity of 1,000 km/s (Because it would be nice
to slow down), you're looking at round trip times of at least seven
months, plus however long you want to stay to work. Voyage duration
comparable to the epic expeditions of the 1700s don't seem out of the
question.

I imagine the Main Belt, Trojans, Centaurs, and moons of the gas giants
will be colonized before we start sending people to the Kuiper Belt.


While I have an irrational interest in Saturn and Neptune,
I expect Jupiter's system will turn out to be the most useful site to
exploit, if we exploit space. While most of the resources of Jupiter
aren't easily accessable due to its escape velocity, the moons are
nicely various and both Jupiter's mass and its planetary magnetic field
are potentially useful resources.

Ah. You like to exploit the Oberth effect. A man after my own heart.

I seem to recall Manx' daughter using one of Jupiter's moons and the
strong Jupiter magnetic field to generate a ridiculous amount of power.
(Manx is a character appearing in a good number of Charlie Stross stories).


In fact, if you can use Jupiter, access to the rest of the
Solar System can become easier.

I believe you are correct.

Hop

In article ,
Hop David wrote:
James Nicoll wrote:

While I have an irrational interest in Saturn and Neptune,
I expect Jupiter's system will turn out to be the most useful site to
exploit, if we exploit space. While most of the resources of Jupiter
aren't easily accessable due to its escape velocity, the moons are
nicely various and both Jupiter's mass and its planetary magnetic field
are potentially useful resources.

Ah. You like to exploit the Oberth effect. A man after my own heart.

The Brain Eater gets us all and I don't want my later writings
to be entirely about the desirability of a trillion person Earth and
perfidity of benderites. Although they probably will be. Anyway, I'm
collecting mania now for use later.

I seem to recall Manx' daughter using one of Jupiter's moons and the
strong Jupiter magnetic field to generate a ridiculous amount of power.
(Manx is a character appearing in a good number of Charlie Stross stories).


I just read the sequel to ACCELERANDO, in fact. GLASS HOUSE,
out in late June.


In fact, if you can use Jupiter, access to the rest of the
Solar System can become easier.

I believe you are correct.

It therefore follows that [sf/x: voice of Dick Tracy] the nation
that controls Jupiter controls the Solar System.
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(James Nicoll) wrote:

ravening beams

Doc? Is that you?

More uses for a gas giant (I think this one is from John
Schilling): use the planet to brake small, extremely dense bodies
almost to orbital speeds, then finish the job within the small
bodies of the rings (Obviously, Jupiter wins in the "a very large
planet" contest, while Saturn wins in the "huge ring structures"
contest). This might allow us to recover stranglets and other
such exotic materials.

I'd take a close look at any small body with an unexplained
internal source of heat energy.
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James Nicoll wrote:

At this point in time, Earth is the richest known source of
fissionables, although it seems reasonable that Mars might also have
ore beds. Io is probably worth a close look, as well.


ISTR biological processes had a part in concentrating uranium ore.

The conventional wisdom is that asteroids lack the geologic processes
that concentrate ore. I would imagine an ordinary chondrite is fairly
homogenous with various substances distributed evenly throughout.

But I don't believe this the case with a comet (or extinct comet) with
an eccentric orbit.

At perihelion internal heat and pressure can liquify volatiles creating
a solution of dissolved minerals & colloids. Brin's model of comets has
a mantle accumulating as surface volatiles are boiled or sublimated off.
I imagine the outer mantle to have vents and tunnels in it leading to a
more volatile rich center. These tunnels are likely narrow in some
regions and wider in others. In the wide rooms of the tunnel some of the
heavier particles might accumulate in a similar fashion to the the wide,
sandy regions of a river.

Hop

In article ,
Hop David wrote:
The conventional wisdom is that asteroids lack the geologic processes
that concentrate ore. I would imagine an ordinary chondrite is fairly
homogenous with various substances distributed evenly throughout.

Bear in mind that nickel-iron meteorites are clear testimony that some
asteroids briefly had active geology -- enough so for the inside to melt
and a core/mantle distinction to get started, with rock in the mantle and
metal in the core -- before they froze and were then broken up.
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James Nicoll wrote:
More uses for a gas giant (I think this one is from John
Schilling): use the planet to brake small, extremely dense bodies
almost to orbital speeds, then finish the job within the small
bodies of the rings (Obviously, Jupiter wins in the "a very large
planet" contest, while Saturn wins in the "huge ring structures"
contest). This might allow us to recover stranglets and other
such exotic materials.

I'd take a close look at any small body with an unexplained
internal source of heat energy.

Enceladus?