The Orion would have to be WAY high orbit, so the EMP doesn't fry all the damn satelites.
Read Niven/Pournelle's FootFall for a fascinating look at an Orion spaceship.
> The Orion would have to be WAY high orbit, so the EMP doesn't fry all the damn satelites.
You say that like it's a bad thing.
If you fry all the satellites, you have to launch all-new ones. That, coupled with the launch system market needed to launch the Orions and their support and maintenance infrastructure, will meant hat flight rate for launch systems will go through the roof, and price will plummet. This means that you will be able to launch a lot *more* satellites, as well as people, including colonists. Which means that even if the Orions fail to stop the comet, civilization will go on... just on the Moon, Mars and asteroids.
Plus... I'm unlcear that high-orbit (GEO to L4/L5) would result in meaningful EMP. EMP is a result of the Compton effect... charged particles hitting the upper ionosphere and causing a big magnetic bloom. But if the bombs are *far* away from the ionosphere, then the charged particle flux would be pretty low, and the ionosphere would not take much of a hit.
> Read Niven/Pournelle's FootFall for a fascinating look at an Orion spaceship.
Even better: Look up back issues from Volumes 1 and 2 of Aerospace Projects Review for info on the *real* Orion spacecraft designs...
http://up-ship.com/apr/apr.htm