>Excellent commentary. However, I point out one concept in asteroidal
>refining that is illustrated in Jerry Pournelle and Charles Sheffield's
>novel _Higher_Education_, which just came out late last year. THis uses
>a large tube constructed of a carbon/carbon type matrix, possibly using
>buckyfiber, surrounded by induction heaters. The asteroid is shut inside
>the tube and heated up to molten level. It is then spun to provide
>centrifugal separation of its components by element, which are each
>drained in series from spigots on the outside.
It's a cool concept, but nature has tried it, and the separation is not that
good. All the planets and most large asteroids have been entirely molten at
some time in their past, and they have seperated into only three chemically
distinct units, thanks to the miscibility of elements:
--Iron, nickel, carbon, and heavy metals. Geologists call this "core" and
steelworkers call it "molten steel".
--Silicates rich in aluminum and magnesium. Geologists call this "mantle
and crust" and steelworkers call it "slag".
--Water, carbon dioxide, and various bad smells. Geologists call this
"atmosphere and oceans", and steelworkers call it "flue gases".
You can spin all you want, but I don't think things will seperate much more
than this, any more than a bottle of ocean water will seperate into a pile
of salt with fresh water on top.
--CarlF