Planetary defense systems are very weak when compared to the defense systems of even a medium sized starship.
The firepower of the planet is added to the fire power of the starbase.
The number of fighters that a planet can launch is the number of fighters that on the orbiting starbase plus the SQR( defense outposts ).
The number of fighter bays that a planet has is the SQR( defense outposts ). If the planet has a starbase then the planet gets 5 extra fighter bays.
If a fighter from a planet side based fighter is hit by enemy fire he is beamed back to the planet .001 milliseconds before the fighter explodes. He is then ready to attack the next incoming ship in a new fighter if the planet survives the attack. Fighter pilots from a starbase are unable to beam out.
The tech level of the beam weapons on a planet is SQR( ( defense outposts ) * 0.5 ) or the tech level of beam weapons of the starbase ( the greater of the two ).
The number of beam weapons that a planet has depends on the SQR( ( defense outposts + starbase defense ) * 0.3 ).
Shield power and resistance to damage in KT/SHIELD is 100 + ( defense outposts ) + ( starbase defense ) You can compare this number to these ships:
B200 CLASS PROBE 30 KT/SHIELD
OUTRIDER CLASS SCOUT 75 KT/SHIELD
MISSOURI CLASS BATTLESHIP 395 KT/SHIELD
BIOCIDE CLASS CARRIER 860 KT/SHIELD
MERLIN CLASS ALCHEMY SHIP 920 KT/SHIELD
GORBIE CLASS BATTLECARRIER 980 KT/SHIELD
Planets can attack ships in orbit using the "NUK" or "ATT" planetary friendly codes.