The founders of the Silicon Valley startup, Planetary Resources, have announced plans for mining asteroids for valuable metals. Peter Diamandis, Eric Anderson and investors including director James Cameron and Google CEO Larry Page are behind this venture.
I’m trying to be positive here. Perhaps these fellows should visit some earthly mines and see what it takes to break actual rock and extract the value from it.
Earth bound ore bodies near the surface are commonly the result of concentration by hydrothermal flows. In the absence of water-based geothermal concentration processes, or recrystallization of PGM’s in magma chambers, the reality of economically viable ore bodies in asteroids is an open question. A lot of survey work needs to be done to answer this question.
Oh, and one more thing. When you blast rock on a largish planet like earth, the fragments fall back to the ground. This won’t happen on an itty bitty asteroid.
The talk about recovering water from asteroids to subsequently crack and make propellant is a large challenge all by itself.
I predict that civilization will slump back to a 19th century Dickensian-style world of robber barons and sharecroppers before any hardware gets to an asteroid. Children will ask “Momma, what’s an iPad?” as they walk from their rundown subdivision to a quonset where they strip insulation from wire for copper to barter for food. It’s all so clear now …
Lamentations on Chemistry 
Why mine. Priced at $4 per gram, there’s money in meteorites. A mere 250t and we’re rich I tells ya.
Aim a resonably sized one at someplace you don’t like. Stand well back and prepare to reap the rewards. Premelted into funky shapes.
Civilisation slump as an added bonus.
\;-)
Asteroids wouldn’t have ores as we know them, however some asteroids are lumps of metal which have undergone a multimillion year long slow cooling cycle from a molten state. I would expect this to result in fractional crystallization of metals from the melt. At the minimum, giant lumps of recoverable metals are better than ores. Blasting would be tough though, you would need some sort of cutting torch or laser.
The main advantage of mining in space is to then use the materials to build things in space, without lifting more material from the gravity well. Between nickel-iron objects and carbonaceous chondrites, quite a range of elements are available.
I don’t disagree that raw materials in space have the advantage that you mentioned. But the industrial capacity to process them into useable objects will have to be lifted into space as well. Let’s say that you find an asteroid with an abundance of Fe or Fe/Ni. The miners will need to detach suitably sized pieces from the asteroid, crush them to a size suitable for their processing equipment, and then, depending on the composition of the ore, ether concentrate it by extraction or flotation to concentrate the value, dewater, smelt or electrolyze to win the metal to some specification to make an ingot. Then the ingot must be formed by casting or machining to a suitable shape for end use. All of this requires vast energy and material inputs and is economical on earth only because of the very large scale and the abundance of energy in the form of electricity. Reductants like coke and slag modifying materials are crucial to the whole process and must be trucked.
Metal properties are sensitive to other elements that are present, like phosphorus, silicon, carbon, oxygen, etc.
Take some time and investigate mineral extraction and metallurgy. You’ll find that it is quite energy intensive and requires a long list of highly specialized equipment, refractory materials, additives, oxygen, lixiviants, water, reductants, etc.
Metals by their nature may be isolated and formed into useful objects only after considerable effort and energy. Maybe there is an abundance of iron and nickel in the asteroid belt. So we’re going to make iron or steel … everything? Aluminum alloys have many advantages over iron in terms of density, but again is highly energy intensive in it’s isolation if taken from alumina.
It seems to me that finding metal rich asteroids is actually only 10 % of the problem. And, processing costs are going to severly wear down the advantages of the raw material already being in orbit.
Hi Gaussling, I think https://www.911metallurgist.com/blog/asteroid-mining complements your article very nicely.