The main governing body for this type of work is the international seabed authority:
A hot area they have looked at is the longing of poly metallic nodules:
While no one has actually started mining operations yet, they are working in that direction, trying to get ahead of the environmental impacts first and foremost.
While there is a strong argument for “protecting” the environment, I don’t see that as a justification in it if itself to not do resource extraction. While not perfect, they seem to be heading toward a conservative approach to mining. In it (at least last I heard) they are deliberately setting aside large swaths of areas with the valuable resource as “wildlife reserves” similar to what we do in the United States, and Australia is going for the Great Barrier Reef.
I don’t know the future here, but there are too many people in this planet clamoring for resources not to look at all options (though personally I would prefer to enable space mining).
Or have been pressured into silence.
There's no argument that environment impact needs to be evaluated--that's just not what these particular people are qualified to assess. It's unlikely that the entirety of academia will avoid discussing the potential consequences of these ideas. Those who are qualified to do so will.
Let's pay the tremendous up-front costs of lifting mining operations out and reap the long (caveat: very long) term benefits of doing so.
edit: In case that came across as sarcasm, I am in dead earnest. Whatever the relative costs of so-called asteroid mining versus deep sea mining, the ecological cost tips the balance waaay in the favor of asteroid mining. It's just that we'd have to have a longer-term mindset than we currently do.
seriously, whatever the (overstated, imo) danger of moving mass into Earth orbit is, it can be mitigated - and probably a lot more easily than the dangers of deep sea drilling can be.
Perhaps this is why China wants to build a moon base
Of course, it's still likely that the costs involved mean this idea wouldn't work in today's market conditions. That doesn't mean that conditions would never change...
Across all materials from coal, diamonds, salt, copper, etc it all adds up to just ~600billion per year in revenue and profit margins that jump all over the pace from year to year.
PS: Rare earth minerals are also generally discarded. It’s the effort to remove them from ore that’s the issue not finding them.
The kind of thing that kind of makes you second guess the "whacky" conspiracy crackpots.