New Book on Space Colonies

>>>
>>
>> This paper is pretty good on the subject: "J.
> Kargel, "Metalliferous
>> Asteroids as potential sources of precious metals", Journal of
>> Geophysical Research, v. 99, no E10, p. 21129-21141, October 25,
> 1994."
>
> Thanks for the info. I'll be ordering a copy of this paper. Is there
> a version on-line or do you have a pdf copy that you can place in
> the files section of the website?

Unfortunately there is no electronic version that I am aware of. I'm
not even sure where my paper copy has gotten to :-(
>
> Sorry, sloppy question on my part. What I meant to ask was how is
> the payload delivered to the Earth's surface. I'm assuming a lack of
> orbital infrastructure, afterall the PGM venture would be at the
> vanguard of orbital development so other than the dedicated mission
> hardware I wouldn't expect there to be much useful equipment in
> orbit. So the material is mined at the NEO site, then shipped by
> reusable transport to LEO. Then what? Thundering impacts into
> desolate areas of the Earth? Or space shuttles waiting around in
> orbit to take on PGM and ferry them down to Earth?

I think you can only make sense of a PGM exploitation mission in the
context of at least some orbital infrastructure. OTOH, if you simply
vapor deposit the PGMs onto the inside of balloons you might end up
with sufficiently low ballistic coefficient that just dropping the
resulting hollow sphere in the desert somewhere would be practical. You
wouldn't want to just drop solid lumps of PGM because they'd bury
themselves on impact if they didn't vaporize.

Alternatively you can just send up a supply of heat shields. I think
you probably don't want to invest any money in trying to bring the PGMs
back to a spaceport in an RLV. Just drop them in big chunks near the
facility that will further process them.

>
> Can specific infrastructure in orbit for PGM mining help other
> industries? How?

Anything in LEO that's specialized for providing delta-v is useful.
Also anything that's capable of repair and refurbishment is useful. If
you have a regular stream of PGM mining ships headed out to NEOs it
makes it easier to send out a ship to mine volatiles (or more likely it
would happen the other way). Just having regular launches of anything
at all would bring down prices.

>> Platinum isn't the most useful - Rhenium has the highest melting
> point
>> of any metal, and it's insanely expensive. Dropping the price of
>> rhenium may help drop launch costs,
>
> Can you tell me more. How is Rhemium used in launch vehicles? I'm
> assuming it has something to do with rocket nozzles?

Rhenium is used in radiatively cooled nozzles. If it was cheaper it
would probably also see use in turbopumps for the turbine blades (which
see very high heat loads from the gas generators). Also it could be
used in thermal protection for reentry, though I think it may be too
easily oxidized to be used without some sort of coating. If the price
comes down then it may be possible to come up with an alloy of rhenium
and something else that can serve as TPS without oxidation concerns.

> As a scientist how would you go about finding more information so as
> to make a better proposal? What info are we missing?

The single biggest problem I foresee is in working with ultrafine
particles of asteroid regolith in micro gravity. The dust is going to
get everywhere, and it is *fine* - moving parts will quickly destroy
themselves if not protected. As soon as you scoop up a little bit of it
you are surrounded by a cloud of dust.

The other major problem I see is simply finding the right asteroid.
Really good ore bodies are on in ten thousand or so. Lousy odds. For
volatiles the odds are much better, maybe one in a hundred or so. I
have ideas about how to do the prospecting, but it's been a while since
I really looked closely at them. I should dust off my old notes and see
if the ideas hold up in light of what I've learned. It'll be a while,
but I'll post something here when I finally get around to it.

......Andrew