Asteroids vs Planetary Mines

[Varyon]

A tangent in another thread threatened to derail it, so I felt it would make sense to split it off here. The discussion is between the merits of processing asteroids for their raw materials and getting those same materials from mining planet-side deposits.

Originally Posted by Daigoro

There might be a cost-benefit crossover point where it's cheaper to mine out a vein of ore than pulverise and process a whole asteroid to get the same output.

Potentially, yes. From what I understand, however, for a lot of materials a good deal of the cost is strongly related to rarity, and if you can economically mine asteroids, that rarity largely goes away, making the cost simply a function of processing the material and taking it from source to destination.

For planetary uses, mining from the ground is probably cheaper, but has a lot of issues associated with it. First off, I suspect it's easier (particularly at TL10) to locate which asteroids have decent concentrations of the material(s) you want than it is to find a vein of said material on a planet. Also, while you need to have your space mine designed to be vacuum capable (and radiation-shielded), you don't need to worry as much about gravity or the environment. Planetside, you often need to dig carefully to avoid collapses, and likely need to be careful with what you do with excess/waste material so you don't end up with environmentalists coming after you. In space, you can basically just chew your way through the asteroid, keeping what you want and using the rest as reaction mass for mass drivers.

It seems to me that, unless there are materials that can only be found planetside (like various flavors of unobtanium), a colonized planet would be unlikely to contain any mines (because who wants to punch holes in a perfectly-good planet?). The planet the TL10 civilization originated on certainly would, but by the time they've reached TL10, those are likely sufficiently tapped-out as to no longer be economically mine-able.