[ExI] Mining the Sky SL Talk I gave today

spike spike66 at att.net
Tue Apr 27 16:16:46 UTC 2010

> ...On Behalf Of Adrian Tymes
> Subject: Re: [ExI] Mining the Sky SL Talk I gave today
> --- On Mon, 4/26/10, spike <spike66 at att.net> wrote:
> > OK, I thought about it longer.  Now I will now explain my 
> thoughts in a parable...Jesus.
> It is also flawed.  I have already explained most of the 
> errors (like your assumption that platinum has no 
> non-financial value on the ground, or even that the value in 
> orbit necessarily dwarfs the value on the ground*)...
> * Another way to think of it: even if the eventual value in 
> orbit is extreme, that's still eventual.Arian

Ja, my notion is that platinum creates its own value in orbit as soon as we
figure out how to use it to make reflective surfaces.  In the asteroid belt,
we have plenty of iron, plenty of silicon.  These are good structural metals
but neither of these are particularly good reflectors in the sunlight
spectrum.  We use the platinum, chromium and silver as reflective layers
over the iron and silicon.

We already have this technology.  Imagine a very thin mylar balloon, 100
meter radius, launched gently from an asteroid, in interstellar space far
from the nearest gravitational influence, inflated to about 10
nano-atmospheres, with a free-floating ion-deposition gun inside the
balloon, vaporizing a ten kilogram hunk of chromium or platinum.  The
balloon is set to rotation about the X axis, the ion gun rotates about the Y
axis, while spraying a tenuous mist of vaporized metal at a rate of about a
milligram per second.  The inside of the balloon is eventually coated with a
reflective surface.  Cut circular pieces out of the balloon, reshape
slightly and you have an enormous solar concentrator.

The free floating ion deposition device need not be connected in any way to
the balloon, for as the ion gun drifted toward the wall of the balloon, the
force of the ions hitting the nearer surface would gently nudge the balloon
away, keeping the ion gun roughly near the center of the balloon.  

With the numbers I arbitrarily called out, the average thickness of the
coating would be about 4 nanometers, or close enough to 30 atomic radii for
platinum.  The ion gun I specified could work on solar power alone at that
flux level and would accomplish the complete ionization of the 10 kg mass in
about four months.  A 15 atom thick average coating of chromium on mylar
would reflect about 20 percent-ish of the sunlight that hits it (if I recall

What could we do with that?

We have all the technology needed to do this today, with the possible
exception of the device needed to cut circular pieces of the balloon and set
them to gently rotating.  But that doesn't sound too hard to me.  The
platinum would make great solar concentrators and solar sails.  I see little
justification for dropping down into the gravity well to collect interest on
it, instead of going straight to the solar sails now.


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