Personally, launching under nuclear power, using properly-designed bombs from a sufficiently isolated area (the middle of the southern ocean), would not create that much damage. Attention would have to be paid to neutron emissions, EMP effects (this might be a problem even in near-earth space), and a few other issues.

None of those are the things to worry about. Ok, maybe EMP's up in the ionosphere... Actually that will be a larger and larger issue as the scale of electronics continues to shrink.

The biggie health wise is the fission daughter products, radioactive Iodines, Strontiums, and other goodies that you get when you split Uranium. Perhaps they can make "cleaner" fission reactions these days but I don't think it's worth it. I'd wan't to see the production ratios before I change my mind on this.

As for the arms, I didn't see any "thrusters" on the arms during the extentions or retractions.

Any thoughts on Buzz's cycler idea?