Michael Lorrey (
Thu, 01 Jan 1998 14:59:20 -0500

Damien Broderick wrote:
> [after bouncing twice from here's another try -
> sorry if it doubles up]
> At 11:05 PM 12/29/97 -0800, JKC wrote:
> > >Mining asteroids will, IMO, completely eliminate Earth mining.
> >
> >
> >I may be a wimp but the idea of using the Earth's atmosphere as a brake to
> >slow down a large irregularly shaped asteroid to change its orbit, as some
> >have suggested, scares the hell out of me. I think there will always be a
> lot
> >of opposition to crashing any asteroid larger than a small bus to the Earth,
> >and if they were that small I wonder if it would be economic.
> The sensible versions I've read use solar mirrors to melt asteroid metals
> in situ, then railgun standardised ingots to a relay station at one of the
> earth-moon libration points, for redirection to earth (after, perhaps,
> reshaping into lifting bodies). Still pretty scary.

Talk about global warming. However, considering that most of the earths
surface is water, even a drunk dart thrower in charge could put a rather
large tonnage in the drink rather than on someone's head. The trolley
sized ingot idea is the way to go. Merely dropping unrefined rocks to
earth is highly wasteful. Use solar energy to power magnetic induction
heated centrifugal refiners, as illustrated in Jerry Pournelle and
Charles Sheffield's sf book _Higher_Education_.

Better yet, why send any metal to earth at all??? Now that the Russian
metals industry is open to the marketplace, metals prices have hit rock
bottom, and since we aren't likely to have any huge world wars anytime
soon (wars are great for eating up metals), rigorous recycling programs
can help limit the need for new ores. Space based metal refining is
meant to eliminate the transportation cost of materials in space from
the present $2000-$10,000 per pound down to earthside commodity levels.
DOing this will open the door for large industrialization of space.

			Michael Lorrey
------------------------------------------------------------	Inventor of the Lorrey Drive
MikeySoft: Graphic Design/Animation/Publishing/Engineering
How many fnords did you see before breakfast today?