[extropy-chat] Space elevator numbers III

[Keith Henson]

At 12:55 PM 2/17/2007 +0100, Eugen wrote:

snip

>I don't have a particular bootstrap scenario, because this is something
>which needs to be tested in practice, in the lunar simulator. What I would
>start with, however, is by setting up large parabolic mirrors from mylar
>(whether inflatable, or spanned on a foldable truss structure), and melt
>regolith in the focus to sheet glass (left in situ) and sputter materials
>(not yet produced locally) producing large areas full of thin-film
>photovoltaics.

If you are at the pole, you can't leave them on the ground.  And how are 
you going to collect the current from the PV surface?

>Once you have large local PV output, you can do things
>like microwave processing, electron beam patterning and welding, and
>ion beam patterning. Structural material would be fused glass (regolith
>is good enough), spun glass, and metal (electrolytically prepared from
>molten ore,

If you want to make metals, you need to sort out the oxides before you 
reduce the metals.  There is lot of aluminum in lunar rock, but getting it 
out as Al2O3 is going to be a major effort.  The Hall process to reduce 
aluminum not only requires 99% aluminum oxide, but uses huge amounts of 
carbon, which is burned up at the anodes.

http://en.wikipedia.org/wiki/Hall-H%C3%A9roult_process

It takes sorting very large amounts of regolith with a magnet, but there is 
a bit of reduced iron from iron containing meteorites.

>might require low-melting salts as additives, but then,
>if you've got a lot of power, being wasteful is not that large an issue
>as long as you're in a bootstrap phase. What would be interesting in
>how how much control logic you need, and whether you can write them
>directly by ion and molecular beams onto substrate.
>
> > Lunar rock is silicon, aluminum, iron (a little free state) and
> > oxygen.  The silicon and aluminum are tightly bound in complex oxides.  Do
> > you have any idea of the steps and chemicals needed to process such rock
> > into metals and very high purity silicon?
>
>Yes. You don't need high purity silicon, because a 100 kg monocrystal
>goes a long way, if sputtered onto glass in um layers. Initially.
>There are several separation stages possible. Microsorting of the
>regolith is possible. Hydrogen reduction

Off hand I don't think there is much in regolith that hydrogen is going to 
reduce.  Please list for my edification.

>(closed-circuit water electrolysis)
>of regolith, and magnetic sorting. Electrolysis in the melt.
>Fractional destillation. Preparative mass spectroscopy.

http://en.wikipedia.org/wiki/Calutron

>About a dozen
>other things I haven't thought of, but other people will.

>It's an experiment, where you improvise and invent along the way.

It not blind though.  Chemistry is a very well understood subject.

>Because this is expensive, you have to scale down size, and do most
>of the prototype work Earth-side, in lunar simulators. NASA has just ordered
>a large batch of simulated regolith, and UHV chambers where you could
>walk in are expensive, but not nearly as expensive as actually soft-landing
>a kiloton of hardware on Moon surface.

Ah, we are already up to a kiloton.

>There's a continuum between macroscale plants and nanoscale plants,
>so a mesoscale tabletop plant can produce output, and can be scaled
>up by replication. It's all about replication closure, not efficiency.

They are closely related.  See the paper Eric Drexler and I wrote on vapor 
phase fabrication.  In that case the apparatus was able to deposit its own 
mass in metal every 8 hours.

> > Am I the only one on this group with industrial process experience?
>
>Keith, you might have lots of industrial process experience, but I'm
>pretty sure you have little to none industrial process experience where
>UHV and energy glut are present, and you have to really strange things.

To this day I have a chunk of sheet metal I made in a high vacuum chamber 
by vaporizing aluminum with a 10 kw electron beam.  I might add that 
getting rid of waste heat is often more of a problem than energy.

>Nobody has such experience, because such processes have largely to be
>yet to be developed.
>
> > Please point out where I have put a price tag on this project.  I don't
> > think I have because I don't have any idea of what it would cost to build
> > or even the sub parts.
>
>How many launches into high Earth orbit would it take to get to get your
>material (counterweight and the carbon nanotube cloth belt) up?

The counterweight is salvaged space junk.  Brad Edwards thinks you can 
start with an 18 ton seed cable.  The cable is not cloth and not a 
belt.  There are no climbers, just elevator cars going up a moving cable.

>If the
>counterweight is an asteroid, which specifically, and how much energy
>is needed to capture it?

Please go back and text search.  Have I mentioned an asteroid as the 
counterweight?

snip
>
> > I think we live an energy poor lifestyle right now.
>
>I agree, but in terms of what you get for a unit of energy, we're
>ridiculous. In a solid state civilization, given a liter of computronium
>and an energy budget of about 100 W, the lifestyle is really really
>really different. And you still get to play with the energy output of
>a star, or more (assuming, the population is so high that a star is not
>enough, and you have to start converting matter to energy on a very
>large scale).

I am writing a novel where 99% of the population has uploaded so in the 
long run I too see a computronium future.  This project is a stop gap 
measure to bridge between now and full scale nanotechnology.  You can't 
quit farming now because people will be living on electricity some time in 
the future.

If discussing space elevators and power sats is too low tech and too near 
term to hold on this group I will move it.

Keith