Planetary weapons has the Smart Bombs for taking out Resupply Depots and Space Ports. They are in the upper half of the field, at tech levels 8, 9, 10 but it's not a very expensive field. You might possibly move them to computers, since they involve 'homing' technology that has to figure out which facility is to be the target. I wouldn't move them down very far in the Planetary Weapons field, though. They can be very powerful. A drone with a 'smart bomb' warhead might be even more effective than a ship armed with the direct-fire weapon. You could send a swarm of drones fairly cheaply (erm, if drones are modded to be cheaper...
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