People tend to have a completely inaccurate view on this because of bad popsci, out-of-context feasibility studies from the 1950s and fiction that just leans toward the "fantasy" on that.
The reasons for this is are very simple:
1) There is no "high ground". Being in orbit does not enable you to throw things "down" for free, thats simply not how orbital dynamics work. All the impact energy you have to pay for up front, and delta-v on some orbital object is almost inevitably more expensive than the equivalent amount of explosives on the ground.
2) Anything launched from beyond earth orbit would be unusably delayed. And telegraphed.
3) The concept does not have a single selling point from a military perspective; not really faster than an ICBM, penetration is limited by newtonian physics regardless of speed and more expensive than just delivering the equivalent amount of explosives (or nuclear payload) via missile.
edit: Yes an interplanetary transport system could be weaponized. But so could the explosives currently used in mining (~tens of millions of tons per year), no one cares.
And we're not even talking about "orbital" bombardment. We're talking about a continuous stream of material at well above escape velocity, whose delta-V is already paid for. Simply redirecting a few pieces of this stream would not be more telegraphed than any other attack. By the way, are you sure the control systems of the mine owners are resilient to coercion of their executives by "legitimate" terrestrial governments? I'm not. None of your reasons are effective.
The energies are substantially more than mining explosives, with wildly different properties as far as threat detection and mitigation. To put it charitably, that's a quite silly comparison.
Edit: now that I'm thinking about it, maybe the best mitigatiom would be to extrude all the mined material into some other very high surface area shape that can't survive reentry, no matter the mass, but can survive being accelerated for the trip home. Maybe a big long truss, with the engine at one end. And then also limit the payload size.
I don't know what exact scenario you are talking about here.
Even a huge construct (1000 tons?) at escape velocity has less energy than the smallest of nuclear weapons (20kt), and a tiny fraction of the explosives used in mining right now (at least megaton TNT equivalent/year).
> By the way, are you sure the control systems of the mine owners are resilient to coercion of their executives by "legitimate" terrestrial governments? I'm not. None of your reasons are effective.
Are you just playing devils advocate here? There is few things that I'm less concerned about than mining explosives being confiscated and repurposed for some shady-government terror campaign.
> If North Korea or Iran could hold the world hostage with a threat of a mass-extinction-level event, they absolutely would. Similar for many terrorists of various stripes. Are you sure the control systems of whatever company ends up trying to bring back mass from space will be sufficiently resilient to hacking? I'm not. So, I worry.
North Korea has weapons of mass destruction already, and delivery vehicles for them. So what? Those destructive capabilities are already much greater than anything they could ever hope to gain from ursurping some space-mining operation within the next centuries.
Russia has even greater capabilities and plenty of imperialist desires to fulfill, but those nuclear threats did not seem to help them gain anything of consequence over the last decade, and not for lack of trying.
The thing is that any organization wealthy/powerful enough to realistically gain access to militarily relevant systems will typically also have enough to lose to disincentivize haphazard use. Rare exceptions like 9/11 demonstrate how much circumstance is required to get around this.
Anyway, in your other reply you're lecturing me about the relevance if the K/T impactor when I'm not the one who brought it up. At least we agree it's irrelevant. If you want to tell me I'm overestimating the threat per ton of incoming meteor, which might be true, go ahead and say that instead of all this other faff.