[ExI] Lunar dirt

[Keith Henson]

On Fri, Jan 7, 2011 at 5:00 AM,  Adrian Tymes <atymes at gmail.com> wrote:

snip

> Silicon dioxide can be reacted with carbon - in coal or charcoal form -
> and heat like so: SiO2 + C -> Si + CO2

I understand the chemistry, perhaps better than most having made a
number of metals and working a lot of chemistry in my misspent youth.
Also have spent serious time inside monster processing plants like a
30,000 ton per day concentrator, copper and aluminum smelters, and oil
refineries.  Plus a few power plants.

The question I have is how remotely run robots relate to a processing
plant able to do something serious.  I.e., what are you proposing to
*do* with them.

> From: "spike" <spike66 at att.net>

snip

> The end game would be to create a rail launcher so that we could hurl lunar
> soil into lunar orbit, and make stuff from it there.  This task is harder
> than any space engineering feat I have seen to date.

Although space elevators may not be possible from earth, they can be
built out through L1 with Spectra, currently used for dental floss.
One able to lift a thousand tons per day (using a moving cable design)
can probably be constructed for a lower mass budget than a lunar seed.
 It's still in the range of 100,000 tons, but it would lift it's own
mass in 100 days.

Lunar elevator pretty much displaces magnetic launchers of all kinds.

That's a big change from the days of Dr. O'Neill.

> From: Eugen Leitl <eugen at leitl.org>

> On Thu, Jan 06, 2011 at 06:21:14PM -0700, Keith Henson wrote:
>> Will someone enlighten me about what remote manipulators on the moon
>> are going to be doing?
>
> The first task would be exploration and mapping of the south
> and north poles. The second part would be building large scale
> thin-film PV arrays to mine volatiles and to build more
> thin-film panels, and then to expand the industry base
> until you can build linear motor launchers.

You can't build lunar mass drivers just anywhere.  Google achromatic
orbits heppenheimer to see why.  So you need a road or something from
the poles to the Lunar equator.  You also need a "catcher" which is a
massive structure in its own right.

>> You don't have a lot to work with; lunar dirt is about as far from
>> useful objects as I can imagine.
>
> http://en.wikipedia.org/wiki/In-situ_resource_utilization

snip

That wasn't the question.  Specifically what are you doing with the
robots to construct something useful>
>
>> I have followed this topic since the mid 1970 and, far as I know,
>> there was never a believable flow chart with rock going in and useful
>> stuff coming out the other.
>
> Keith, I thought your knowledge of chemistry and geology was
> better than this.

snip

It good enough, I think, to call BS on vague handwaving.

>> Take solar cells.  Anyone have an idea of what sort of plant it takes
>
> I have a very good idea of that, yes. I've even toured the facilities.

The oil refinery like facilities where they purify the silicon?  Where
did you find one that would give you a tour?  Or do you just mean the
end stage where they mount cells?

>> make silicon?  What inputs the plant takes?  What has to be frequently
>> replaced?
>
> Current CdTe takes about 10 g/m^2. That's 100 m^2/kg. 10^5 m^2/ton.
> At 10% and 1.3 kW/m^2, that's 13 kW/kg, 1.3 MW/100 kg, or 13 MW/ton.
>
> Assuming you deliver 100 kg packages, each will be good for over
> a MW of power.

What are you going to deposit the CdTe on?  How do you make it?  What
do you use for wires to get the power from where you make it to where
you use it?

I am not saying it's impossible, just poorly thought out.  Few numbers
on power consumption, heat rejection, production rates, etc.  And
don't forget the scaling problems up *or* down.

Keith