That's where meteoric iron comes from: https://en.wikipedia.org/wiki/Meteoric_iron https://en.wikipedia.org/wiki/Meteoric_iron Two problems with this: • There

That's where meteoric iron comes from: https://en.wikipedia.org/wiki/Meteoric_iron https://en.wikipedia.org/wiki/Meteoric_iron Two problems with this: • There's not that many meteorites to go around. • Elements more volatile than metals (say, water) boil off and/or ablate off during atmospheric entry. If we want to have those, we'll need to mine them in space and shield them during re-entry. That is assuming we even want to bring those minerals back to Earth. Most proposals intend to use them in-situ to supply spaceborne operations – theoretically, launching the equipment necessary to strip-mine an asteroid is vastly cheaper than sending up the same amount of raw resources. If we can refine those resources efficiently enough in space, things like the ISS or Lunar bases become a lot cheaper. (Practice is, as always, a lot more complicated.)