Re: Beamer

From: Robert J. Bradbury (
Date: Fri Dec 14 2001 - 08:10:00 MST

On Fri, 14 Dec 2001, Anders Sandberg wrote:

> What would the efficiency of simple moon made photovoltaics be, and
> what about the energy requirements for mass sorters and robots?

Regular Si solar cells are certainly feasible in the 10-20% region
(the lower efficiencies being poly-silicon which may be easier to
produce on the Moon). You might be able to push it up to ~24%. But
you have to use multi-layer cells made from different materials with
higher and lower energy band gaps to get into the 30+% region.

If you are using nano-mass sorters like the single proton massometer
from Nanomedicine, I suspect the energy requirements are very low.
If you are talking macro-tech they are probably quite a bit higher.
In mass-spec sorting you have ionize the atoms to put a charge on
them so you can accelerate them through a field that will sort them
by mass.

> Seems like a fun exercise to calculate the optimal rate of
> construction of photovoltaics, mass sorters, utility robots and
> assembly factories to get maximal growth rate.

Most of the information needed for this is in the Freitas Space
Automation study and related "Space Manufacturing" conferences
from the '80's and early '90s. I just haven't had time to get
much of it online and it seems unlikely that that will be the
case in the near future.


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