According to project Thor, it would not be that cost efficient. The wikipedia page states that the rods would need to be at around 8 tons. A ton of tungsten is around 50k$ so 8 tons is rather negligible. What is very expensive is to get 8 tons of material to space. During the space shuttles era, bringing a kilogram of matter to space would cost around 20k$. A ton is 907 kilograms.
8 x 907 x 20 000 = 145M$ per payload.
I don't have the exact numbers for the cost of an ICMB with a nuclear warhead but I'm pretty sure that it is less than that. We also didn't factor in the cost of maintaining an orbital launcher, possibly manning that thing and other costs which being in space incur.
Maybe with newer launch methods bringing goods to space will be cheaper, but I don't think we'll see this kind of tech unless costs decrease to around 2000$/kg to space (1/10th of what it is now).
> As of March 2013, Falcon Heavy launch costs are below $1,000 per pound ($2,200/kg) to low-Earth orbit when the launch vehicle is transporting its maximum delivered cargo weight.
Well we are reaching an age (of asteroid mining) where it's probably more cost efficient to manufacture in space and ship (or railgun, I guess) the mass to earth. Probably not for a while, but I don't think it's science fiction anymore.
That gives me an interesting idea. Do you think it could be feasible to mine ore from space and then drop-ship it to some low-depth (a few hundred feet at most) part of the ocean? The heat from re-entry would likely turn the metal into a molten blob, and the sea water would rapidly cool it.
8 x 907 x 20 000 = 145M$ per payload.
I don't have the exact numbers for the cost of an ICMB with a nuclear warhead but I'm pretty sure that it is less than that. We also didn't factor in the cost of maintaining an orbital launcher, possibly manning that thing and other costs which being in space incur.
Maybe with newer launch methods bringing goods to space will be cheaper, but I don't think we'll see this kind of tech unless costs decrease to around 2000$/kg to space (1/10th of what it is now).
http://en.wikipedia.org/wiki/Kinetic_bombardment