It's early days, but costs per pound to space are going down fast. The tech itself isn't science fiction we can sinter a cannonball from lunar dirt or extract a

It's early days, but costs per pound to space are going down fast. The tech itself isn't science fiction we can sinter a cannonball from lunar dirt or extract aluminum and make a ball to put in a catapult. It's just plenty expensive as yet, but costs are coming down. You're right, according to me, about getting minerals from the asteroid belt, for earth use. That's not happening until the farther future: the delta is extreme, and down to earth itself not trivial. But extraction from the moon or mars moons (about the same delta to a lagrange point as the moon believe it or not) can be economical in bulk precisely because the cost to get to earth orbit can only go down so far (the cost of the fuel). Fulton used to loiter around the fences around his steamship as it was being built; you should find and read all the scorn every single passerby had for the mad, doomed project that seems pretty ordinary now. When I was young, maybe 1963, I had dreams in which people in the future were carrying around small devices with screens they kept looking at, about the size of my fathers pocket calender planner (3" by 6" maybe). Not a wholly original idea, Dick Tracy comics showed a TV watch back then. My father, a very competent electronics engineer who was very well read, poured absolute scorn on the idea. He didn't just say that no known tech could do that, he said that the device was strictly impossible, and that no matter how long the world lasted, no such device would or could exist. His reason: you can't flatten a cathode ray tube that much. Time easily dispenses with our reasons why not.