If you look up the wikipedia article on nuclear test ban treaties, you will see that they are explained in terms of "environmental concerns", and pressure from environmental groups. Now, I have no doubt that environmental groups have no great love for nuclear bomb explosions on land or sea, or even in the atmosphere, the environmental damage in the immediate area would be instantaneous and massive. Actually, almost absolute. However, I very much doubt the first partial nuclear test ban treaty, signed in 1963, just after the Cuban Missile Crisis, was primarily motivated by environmental concerns, in any normal sense of the term.
Kennedy: "You know, Nikita, it's true that I'm from a family that believes in winning at all cost, that my father got rich rum running and hanging out with gangsters, and that I just launched a 20 Megaton thermonuclear missile into space specifically to screw up the Van Allen Belts, and make it more dangerous for your unmanned Sputniks and manned Vostoks to travel there, but, I've turned over a new leaf. I've become a born again environmentalist. I've even written a speech in which I say 'Ask not what your country can do for you, but what you can do for the environment.' So let's sign a nuclear best ban treaty."
Khrushchev: "Jack, you're right. Yes, I'm a virulent Marxist who exterminated millions of his own people in Ukraine for purely political reasons. And, it's true that I just exploded a 50 Megaton Tsar Bomba in the high arctic just to show you what the USSR is capable of. But, suddenly, I'm deeply concerned about the possibility of the ice caps melting. So, let's sign the nuclear test ban treaty."
Actually, what Kennedy and Khrushchev were concerned about was the very real possibility of an all out thermonuclear holocaust occurring by accident, as may have almost occurred during the Cuban Missile Crisis. And, what they were trying to do, by banning all nuclear testing except deep underground, was move towards the elimination of nuclear weapons. Period. Clearly banning the explosion of nuclear bombs in outer space, as the 1963 treaty certainly did, does not bear very directly on the earth's environment. "Outer space" extends to the very end of the universe, after all.
So, really, the nuclear test ban treaties aren't about protecting the earth's environment, particularly, they're about the ultimate elimination of this explosive nuclear technology because nuclear explosives represent a direct threat to government authority and power.
Arguably, governments have been trying to shut down nuclear research since 1952, with the first explosion of the H-bomb -- a weapon so powerful, that even the largest governments in the world couldn't possibly survive the explosion of just a few dozen of them on their territory. There is nothing on this planet so regulated as nuclear explosives. Aside from the nuclear international test ban treaties, regulating all governments, there are the limitations on the possession of Uranium by individuals, institutions or businesses -- in the U.S., no one is allowed to possess more than a few pounds of Uranium.
Now, the problem here, is that pretty much anything that can be useful, can also be harmful. So, the immense power of nuclear explosives, which could probably be harnessed for space travel, energy production, etc. is simply not being exploited, at all. Surely, we could explode nuclear bombs in deep space without destroying the earth's environment. And, isn't it likely that opening up this area to research again might well yield practical benefits for civilian application? So, let's suppose we put aside the nuclear test ban treaties, at least for nuclear research in deep space. Wouldn't that be a positive thing, on the whole?
