Planetary Defense Weapons (think v-150 Ion Cannon from SW)

So as the title implies, I think it would be a nice addition to the game if there were planetary defense systems. But not like the ones that we currently have, that increase the number of boots on the ground, or prevent x amount of population/system improvements from being destroyed during an invasion, but planetary defense weaponry. 

Mechanically it would act similar to the 'Ward of Auriga' from Endless Legend, damaging enemy fleets (ones from factions in a Cold War or War) for x amount of damage if they orbit or blockade one of your systems. 

They could also affect battles similar in the way Ion Cannons and Planetary Turbolasers could fire on ships during a space battle in Star Wars: Empire at War (if anyone remembers that game). 

However, in ES2, the planetary defense system could be used by a battle card and/or when you're in a space battle over a planet with the system improvement, it'll fire at enemy ships in the battle. For balancing purposes it would work similarly to the 'Blast Effect Battery' firing once every phase or every battle (and probably hitting only one ship or a cluster of ships).

Also since planetary defenses are generally the first thing targeted during an invasion, the system improvement could be disabled or destroyed by orbital bombardments. 

Visually they could be similar to the v-150 Ion Cannon (SW), w-165 Planetary Turbolaser (SW), the SMAC orbital platform (Halo), or any other similar improvement. 

There could also be a quest specifically for it, similar to the Mavros Fighter Bomber Quest. 

Or a searchable tier 4/5 Curiosity that gives you Endless Technology that you can reverse engineer to make one (since there is already a number of buildings that you can build after receiving them from searching an anomaly) 

v-150 Ion Cannon

w-165 Planetary Turbolaser 

SMAC Orbital Platform 

Cheers~