I think that, when all is said and done, the end result of three decades' worth of environmentalism is that we're going to get the propulsion system we need and be able to sleep soundly at night knowing it won't End Life On Earth As We Know It.

Things were a lot looser forty years ago when they were working on Orion. That technology was brought to us by the same people who assured us that we could survive a nuclear war by digging a shallow trench in the dirt and covering it with plywood. It's not a bad thing that the nuclear safety bar is a lot higher today than it was then.

NASA's going to be fully mindful of the need to prove that any nuclear propulsion system it builds won't have harmful side effects. It'll have to satisfy the majority of environmentalists, though I'll concede that the more extreme environmentalists will never see beyond the word "nucular".

It won't be hard to prove the safety of a propulsion system intended for use only in space--vacuum is a powerful prophylactic. The sticking point is going to be construction and launch, and there we have the precedent of almost four decades of RTG use to go on.

No need to borrow trouble, Phil. Preemptively taunting environmentalists is simply going to cue them to oppose the idea. It's better for now if the plan gets a minimum of publicity.

I think it'll fly...

--Robert