You've got to find a way to go from over 20,000k per second to stationary on the ground. For any worthwhile mass of asteroid you bring back to Earth, it's going to require one hell of a heat shield during reentry.
So maybe you leave the heat shield in orbit, but you've still got get it there.
I think space mining becomes possible when you're no longer cornered by the rocket equation. That is, it's going to require a breakthrough in propulsion systems.
> I think space mining becomes possible when you're no longer cornered by the rocket equation. That is, it's going to require a breakthrough in propulsion systems.
I think near-Earth space mining and manufacturing is what can help us get over that limit in some way - LEO is halfway to anywhere in the Solar System ∆v-wise, so whatever part of your mission you don't have to lift upwell makes for huge savings in fuel (and for many missions, you can use weaker and more efficient engines once you're on a stable orbit).
I imagine that platinum will be the most important metal mined from asteroids and returned to Earth. Thick platinum shielding should hold up well on atmospheric entry.
So maybe you leave the heat shield in orbit, but you've still got get it there.
I think space mining becomes possible when you're no longer cornered by the rocket equation. That is, it's going to require a breakthrough in propulsion systems.