From: Eugene Leitl (Eugene.Leitl@lrz.uni-muenchen.de)
Date: Sun Oct 21 2001 - 16:10:58 MDT
On Sun, 21 Oct 2001, Spike Jones wrote:
> Why would we need to patch holes? Assume an inflatable dish
> could be coated on orbit, then no bother if it gets a few holes.
It needs not even be inflatable, an aluminized mylar foil spanned over a
very light truss structure would do. Experiments with inflatable
structures which polymerize after inflation have also been done a brief
while back by the Russians (where are they now?).
Notice that all this is worse than useless in LEO: the drag will deorbit
you very quickly.
> Depends. PVs are harder to make on orbit than coating
> an inflatable surface on orbit, assuming current technology.
Costs for current space-grade PVs are so high because due to very
expensive transport costs/kg they're attempting to minimize the weight.
Given that some of the cell types have highest efficiency at twice to
thrice the solar constant flux, using (very lightweight) mirrors still
does make sense.
If material is essentially free (Luna surface, asteroids) you would
optimize for given cell plant processivity and cell efficiency. For
instance, you could melt lunar regolith with a mylar foil solar oven, and
sputter diverse silicon/dopant and metal layers on top of it. Since the
layers are just microns thin, you can just transport raw pure silicon and
metal to ramp up surface area quickly. After that, you can start producing
everything in situ but the dopants, and later even them, making full
closure.
-- Eugen* Leitl leitl
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