Comment Re:Controlled descent? (Score 1) 148
It would probably be a lot cheaper to bring an asteroid to Earth first and then mine it, rather than send robots up to do it.
That's true of the first asteroid, but after that, you get too much loss from having to send out the scouts and sample collectors from the Earth's surface. The advantage with this system is that once it's set up, they can build their spacecraft in space. That saves the energy costs of a ground to space launch.
It's also worth noting that energy is cheap in space. On the ground, you either have to worry about radiation (fission reactions) or atmospheric loss (solar power). In space, solar panels are effectively more efficient, as they can operate around the clock (no night) and with direct solar radiation. Therefore, a factory built in space does not require earth bound resources to operate.
The first phase (where they launch everything from the ground) is incredibly expensive and offers minimal return. Once they are set up though, it becomes much cheaper. Your proposal would leave them always in the expensive first phase. It is a cheaper version of the first phase, but that doesn't help since the first phase is so much more expensive.
That's essentially been the problem with our space program. We've always been in the first phase. We launch everything from the ground, which uses up ground based resources. This is expensive. What if we changed to only launch people from the ground? It would be much cheaper and easier to obtain iron and other needed minerals in space. Until we do that, our space program cannot sustain itself. It's a drain of resources, not a generator.