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.

[Fred Brackin]

Originally Posted by 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.

You speak of "concentrations" and "deposits" and asteriods probably lack those due to a lack of geological processes. It's probably easy to mine for water ice or similar things but if you're going to grab all those precious metals in those M-type asteroids be prepared to take the whole thing apart atom by atom and then sift those one at a time.

In a certain sort of fiction from the late 70s this was done with a "Santa Claus machine" which was a fusion torch that ionized the asteroid material and then separated the different isotopes in a giant magnetic ring.

A couple of decades alter they started doing it all with magic nanotech but yo don't do it at all with any process comparable to a TL7-8 terrestrial mining operation. Maybe your space setting has Santa Claus machines or magic nanotech but decide that first before people there routinely do asteroid mining for heavy elements.

[AlexanderHowl]

From the evidence that we have seen from exosolar asteroid belts, ours is pretty puny. Systems with large asteroid belts will likely be prime candidates for colonization, as they would have massive amounts of available resources. NASA has already figured out asteroid mining, by the way, and you only need a solar oven to separate out the materials by melting temperature.

In general, it seems that every +1/-1 change in RVM would roughly correspond to a quadrupling/quartering of the mass of an asteroid belt relative to our Main Belt. Within our own system, this would mean that, if the Main Belt was a RVM 0, the NEAs would be a -4, the Hilda Asteroids a -3, the Centaurs a -2, the Jupiter Trojans a -1, the Neptunian Trojans a +2, and the Kuiper Belt a +3. We have already found examples of +5.

Even if a system is only less rich in astetoids than our system, a single large M-type asteroid could supply its needs for tens of thousands of years. A system low in asteroids probably has correspondingly low RVM on its planets, as it is the bombardment from asteroids that renew supplies of rare elements that are being drawn into the planetary mantle by subduction, so asteroid mines will be even more valuable. In addition, superscience that allows for easy space travel makes asteroid mines even more attractive, not less attractive, as it becomes affordable to ship low cost materials like iron down the gravity well in order to exchange them for organics.

[Fred Brackin]

Originally Posted by AlexanderHowl

NASA has already figured out asteroid mining, by the way, and you only need a solar oven to separate out the materials by melting temperature.

Someone associated with NASA in soem way may ahv3e waived his hands over a piece of papre and said 'Hey Presto!" but there have been _zero_ practical demonstrations of melting M-type asteroid material in microgravity to extract the platinum from the nickel-iron.


If you want to melt the water out of an asteroid and collect that vapor that's probably easy enough.

[malloyd]

Originally Posted by Fred Brackin

You speak of "concentrations" and "deposits" and asteriods probably lack those due to a lack of geological processes.

This is definitely still the major bit of information we don't have but need to decide if asteroid mining is practical at all. We just don't know how differentiated asteroids are, and won't until we have samples from multiple spots on several of them.

If there aren't any high concentration deposits then no, asteroid mining is not competitive - if you can get something out of "average" concentration rocks, we have plenty of them on the ground, not to mention much more concentrated "ores" like sea water. Or landfills.

[AlexanderHowl]

Analysis of metallic meteorites suggest levels of up to 250 ppm of precious metals (a typical rich vein in planetary mines has 5 ppm), so we are talking about undifferentiated objects that are equivalent to the richest veins in the richest mines on Earth. Even 'poor' M-type asteroids likely have 30 ppm of precious metals, making them more than competitive with planetary mines (by comparison, seawater is less than 1 ppb precious metals and mine tailings are usually less than 0.5 ppm). Now, S-type asteroids are likely not that worthwhile to mine because of a lack of differentiation, at least as a primary activity.

[Anthony]

The main virtue of asteroids is that most siderophile elements on Earth are trapped in the core; hence the reason people talk about platinum-group metals (most of the group 4/5 elements are common enough that being relatively rare is still not a huge issue, though palladium might be of interest).

[Anaraxes]

Originally Posted by AlexanderHowl

a typical rich vein in planetary mines has 5 ppm),

The World Gold Council defines "high grade" ore as 8+ g/t (ppm), while "low grade" ore is 1-4 g/t. Open pit mines have lower standards (perhaps a tenth as high). 5 g/t wouldn't be considered especially "rich", but merely average. The highest grade underground mine in operation is 44.1 g/t, with a couple of runner-ups over 20 g/t, and the top ten all clocking in at over 11.

[johndallman]

Originally Posted by Varyon

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?).

Possibly no metal mines, but sand and gravel are naturally created and partly sorted by weathering processes. They are used in such vast quantities for construction that bringing them down from orbit is unlikely to be worth the cost.

[Tyneras]

In a realistic near-future setting where the cost of getting into space out of a gravity well is massive, the primary value of asteroids is getting material for space infrastructure that doesn't have to be lifted out of a gravity well. The occasional asteroid with a high concentration of something will be valuable to Earth, but that's more of a "crash the gold market" sort of event, not really the sort of thing that radically changes the balance of common industrial metals like iron. Cool new things might happen when gold or platinum or iridium become common and relatively cheap, but that's still a specialist niche.

If you come up with a mega-engineering project that lets you mine directly into the earths core, you render the entire asteroid belt industrially irrelevant, you now have more of everything than the entire belt combined. Of course, that also sounds like the kind of project that would been a lot of platinum and other stuff from the asteroid belt to get started.