...Though it was never built or tryed, Orion seems to be a good workhorse for heavy-moving...and could be parked and idle for long periods in orbits awaiting future use. It could never be ordinarily used in-atmosphere due to the fall-out it would create. I say "Ordinarily"...But.. if a large asteroid were to approach on collision-course, it might be the only means available to reach and deflect such an object.