The rule system is predicated on the assumption that targets are moving and actively avoiding trying to be hit. But I've seen no mention of what sort of bonus should be applied to attacks against targets that aren't moving or can't move. Things like orbital stations, or fixed gun emplacements and shield generators on the ground. Is there any RAW for this already? If not, what do you do in your games?
On a related note, it's always bothered me that a shooter gets a setback for a target that's prone, but no bonus because that same target isn't moving. IRL it's easier to hit a stationary & prone target than a moving & upright target.