An Orion pulse unit would be good against an asteroid in that, unlike a gravity tractor that means you have a long Rosetta style matching trajectory before you can even begin a mission.
Huh? I get what you're saying about the Orion engine, but the above sentence does not make grammatical sense. Are gravity tractors made by John Deere or Caterpillar?
A gravity tractor is a spacecraft orbiting an asteroid and using its own gravity to pull the asteroid off couse my thrusting away from it slightly.
Not much more purchase than a gnat pushing a semi, but that's the idea. I'll take the nuke.
Comsats are in geosynchronous orbit. They don't wander around. They're either over the U.S. or not.
Yes and no. Such comsats are are over the equator. The USA is below them, down and to the northeast. From our vantage point, the comsat is up and to the southwest. That is why most if not all dishes are pointed in the same direction.
Now in terms of wandering, geosynch comsats do wander a very little bit--a halo orbit in a figure eight. http://en.wikipedia.org/wiki/Analemma
There is a difference between geosynchronus and true geostationary.