AsterAnts

> A lot of things are cast. Casting isn't particularly difficult, but
> there are economies of scale- you need quite a lot of energy to
> melt metal and its cheaper in bulk. It's typical to only melt metal
> once a week or so if you have the facilities and many shops don't
> have the facilities. Solar ovens remove this scaling issue don't
they?

Yes, one of the HUGE advantages to forging in orbit.

> Drill bits I'm not totally sure about, but I think they cast them,
> and then sharpen using millstones. Clearly you need a less
> malleable and more brittle metal for drill bits; the metallurgy is
> important- carbon levels.

Yes, carbon levels are important as well as how you quench the
original cast, but I don't want to go off on a metallurgy discussion.
Drill bits, lathe tools and milling tools are relatively light
compaired to the machinery necessary to make them. They can be sent
up on resupply missions. At a later time, when the station operations
are expanded, they could be made on orbit (is "on orbit" or "in
orbit" the correct phrase?).

>

> > It takes only a 2 or 3 days to go
> > to the Moon, but perhaps 8 months to Mars, and this is a
discussion of going
> > a comparable or greater distance.

Time is only a significant factor when you send people.

> Yeah, but leaving the moon requires much more propellent. ION
> drives only need tens of kilos of propellent, whereas the moon
> needs more like equal propellent to the mass you are launching. And
> the Russian Hall effect thruster ION drives can run on mostly
> oxygen which is easy to separate from ore.

>

Also, you require more propellant to LAND. An asteroid of the size
and mass we are discussing has no apreciatable gravity well. You
don't land on it, you dock with it.
Don't forget that if you're mining the moon, you have to send a lot
more equipment for the propellant manufacturing. You also have to
send people to maintain it, and supplies to maintain the people, and
all the propellant to land all of it AND launch it all from earth.
You're now talking about an order of magnitude larger operation.

king_rodent (putting the eek in geek)