I'm curious if we could mine in areas where large asteroids impacted and gets lots of minerals. Why do asteroid mining if we already have a few in the ground?
• 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.
I did a short analysis on the all the different types and sizes of meteorites if you are interested. The data is based on the meteorite dataset provided by the US Meteoritical Society.
I saw a documentary a couple of years back which looked into a correlation of former (likely/suspected) meteor impact sites and natural resources. It looked like lots of areas rich in interesting metals/minerals turned out to probably have been hit by meteors in the past.
So in a way, we are doing that already (at least if that documentary was not totally bogus).
One factor is that we can choose which of perhaps hundreds of thousands of asteroids are worth mining, while with past impacts we only get what we happen to have been given.
