It’s amazing how people, even smart people, can be trapped by the past.
Take the acquisition of metal, for example. For all of its existence, two hundred thousand years, the human race has known only one general way to get metal.
Having single humans go wandering around beating on rocks and dirt at random. And when that single human finds rocks or dirt with the desired metal, huge groups of humans descend and start beating metal out of all the rocks and dirt they can find. And when the surface rocks and dirt run out, tearing giant holes in the Earth to get more rocks and dirt to beat on. Holes so big you can see them from space.
From Day One of the human race’s existence, this has been how we get metal. Even today, two hundred thousand years on, we still do this the exact same way, if more efficiently and in greater quantity. We send individual humans wandering around beating metal out of rocks and dirt, then groups of humans descend to beat more metal out of more rocks and dirt.
And people have become trapped by this old way, this old idea. To the point where, when they consider space and the future, all they see out there is the past---and more rocks, if not dirt. To the point where nations are actually starting to fight and snarl at each over asteroid and Moon mining rights, even when a far more, efficient better way to get metal was found over a hundred years ago. Even academics, who of all people should know better, are getting into the act.
Entrepreneurs are also starting to form asteroid mining companies. (And here.) Somebody needs to gently jog their elbow and show them this article. Before these tech geniuses wind up flat broke and living under a bridge in San Jose.
There is a problem with that old way of getting metal which has a direct bearing on why asteroid mining will never, ever, be allowed to happen.
The concentration of metal in rock is in general EXTREMELY low. A gold concentration of forty-four parts per million (forty-four grams in a million grams) is considered high-grade ore. Twenty thousand ppm copper (a mere 2%) ore is considered to be very high-grade ore. So to get, say, a pound of metal, you basically have to process fifty to a hundred thousand pounds of rock.
For space mining, all of the above problems with getting metal will continue to be true. Even in space, you will have to send out hundreds and hundreds of prospectors, miners, and robots, and you will still have to process a LOT of rocks.
How incredibly inefficient--- and EXPENSIVE---to say the least. But people have just gotten used to this, and the idea there’s a much, much better, simpler way is going to seem bizarre.
But there is a truly extreme danger that is completely unique to space mining. So extreme I suspect the human race, after balancing the risks and benefits, will simply decide to ban all forms of space mining, period.
Rather than mining an asteroid---it is also possible to DROP an asteroid.
Consider the security risk. Hundreds and hundreds of lone asteroid prospectors. Hundreds and hundreds of space miners. Every single one of whom is going to know exactly how to drop all the asteroids he wants on Earth.
One asteroid from nowhere the human race could handle. Not ten asteroids. Not a HUNDRED asteroids. The threat potential is just unbelievable. 9/11 times a thousand. Entire cities, countries gone, all in the same ten minutes. The more the responsible authorities contemplate the threat potential, the more the responsible authorities will be inclined to never let this threat happen in the first place.
Particularly when they are made aware of a much, much better, easier, CHEAPER way, with an easily manageable threat potential.
What is this easier way?
Well, along about 1900 or so, the human race figured out what elements---metals, for the problem we are considering---were made of. They're made of neutrons and protons and electrons. Now the human race understood exactly what elements were and why they had the properties they did.
In particular, they knew what to do to change one element into another element. Add protons to or subtract protons from a nucleus, maybe add some neutrons to stabilize the new nucleus, sprinkle with electrons to taste, and waddya know, you have changed one element into another element. Transmutation, that Holy Grail of the alchemists, suddenly was, at least theoretically, an easy thing.
Practice was another matter. The power needed was well beyond anything technically possible, then or today. Gigawatts and gigawatts of power pouring in for basically forever. All that power is needed to generate both very high temperatures and very strong magnetic fields, to force protons together close enough so they bind to each other instead of repelling each other.
I suspect you would have to have tight control of your reaction plasma. VERY tight control. If your control slips, you stand a good chance of an accidental megaton thermonuclear blast wiping out a significant fraction of the Earth's surface.
I hasten to add fusion reactors are not a problem because the plasmas are so very small. If your control slips a little, they just go out. A fusion factory, on the other hand, will have to generate huge amounts of mass that will require very large plasmas, hence I imagine there will always be a risk of a fusion factory going up in a mushroom cloud.
If you add all these factors up, there is simply no place on Earth with enough power and with enough safety space around it that a fusion factory could be built.
Not on Earth, anyway.
Strangely enough, there is actually one place fairly close where there is power flooding out by the gigawatt forever and the occasional accidental megaton thermonuclear blast is not a biggie.
Sun-powered fusion factories.
It all fits. Here is the broad outline of one way, although I certainly challenge the physicists out there to find a better way.
Drag ONE iron asteroid in from the Asteroid Belt. Dangle it close enough to the Sun to make it a little mushy. (If purity is a problem, there is a chemical technique called “zone refining” that will solve the problem quite neatly.) While it’s mushy, forge it into a series of concentric iron doughnuts. Pull it back and let it cool.
Iron is a conductive metal. Position the concentric doughnuts close enough to the Sun so electric currents are induced in the rings. This will generate an electromagnetic field in the middle of the rings. With big enough doughnuts, you will easily have a field intense enough in the middle to generate practical transmutation plasmas.
One fortunate accident of Nature. Iron can also be a feedstock for our fusion factory. There’s plenty of it floating around out there. It’s conductive so it’s easy for an electromagnetic field to grab it. The left-overs from our starting asteroid can be the first material to be transmuted. The first batch will be free.
The Sun is, I point out, ALREADY a transmutation plasma. It is transmuting hydrogen into helium. We would only be re-directing the transmutation to more useful elements.
And now instead of scrabbling around in the rocks, risking our lives and our civilization, crossing our fingers and hoping for a one-in-a-million strike, we can simply turn the dial to “Samarium” or whatever and make all we want. One more ancient problem of the human race vanishes quietly away, one more victim of the human race’s advancing technological power, no muss, no fuss.
And no security problem. No looking up at the sky and watching the asteroids coming in to destroy civilization because some terrorist finally got lucky.
Gold, well, now, the sudden ability to manufacture gold bars by the million could be a problem, but the human race has already mostly moved away from gold as a measure of value.
Sun-powered fusion factories could be reconfigured for other purposes. The Sun is known in astronomical circles as a "mildly variable" star. What this means in the real world is every once in a great while the Sun emits titanic blasts of civilization-destroying plasma. If we made those Sun-powered fusion factories self-replicating, it would then be possible to predict and control those random, civilization-destroying outbursts, and possibly even stop them from happening in the first place.
The Sun is also going to have a problem with expanding into a giant red ball and burning up the Earth one day because it has run out of hydrogen. Self-replicating fusion factories could also be re-purposed for removing helium and injecting hydrogen to keep the Sun a nice stable yellow medium-sized star for as long as the human race wants.
If those SETI scientists really want to find advanced alien civilizations (which would show my initial postulate was wrong), the way to do it is look for Suns that are somehow far more stable than they ought to be. Not Dyson spheres, not ring worlds, not Kardashev-type civilizations. Just Suns that have done lots and lots of nothing for millions of years.
If Yuri Milner really wants to do some good for the human race, he should abandon that foolishly conceived SETI project and put the money into developing space-based Sun-powered fusion factories. Return On Investment, which is impossible to calculate with prospecting, is easily calculable for Sun-powered fusion factories, before you have to spend a single dime. Unlike that SETI rathole, Yuri will certainly get much, much richer, maybe even enough to become the world's first trillionaire.
And that’s why asteroid mining will never happen.
Erbium? Thulium? Californium? Ytterbium? Gadolinium? Scandium? Yttrium? Lutetium? Lanthanum? Neodymium? How many thousand tons do you want? Any particular isotopic ratio?