The issue i tend to run into with the defense platforms is the fact that ships always just swing around them and run to bombarding my planet. If everything was built "orbiting" then even things like trade ports, refineries, and research labs would still stay within the net of the defense platforms.

One way to do it is for the player to be able to set a path (like a track) that the turrets will move back and forth on. Of course there would be a limit to the size of the track and say you wouldnt be able to create a path that intercepts any other structures so there are no collisions. Also once an enemy comes in range the turret will hold position within firing range. If the enemy moves away in the same direction as the turrets track then the turret would follow until it runs out of track and the enemy leaves firing range.

Just an idea. I'm fine with defenses the way they are since you can build a whole lot if really needed.

I agree. With as many as we can deploy, I find them useful, though obviously they won't stop an attack. If they did, imagine what we would have to go through to take a planet.

The point of the defensive structures is to slow down the enemy and/or aid your fleet. Personally, it's all about placement of certain structures to draw the pirates into the defensive net I create. The AI, on the other hand, doesn't bee line to my trade centers, so . . .

Well, if everything orbits at the same pace, "Collisions" wouldn't be an issue... unless you have your ships in the way but they should be smart enough to avoid sitting in the path of an oncoming structure... then again this would also be a good use of the Z axis

That's true the AI does work a little differently than the pirates, but I normally put a ring of defenses around my planet that keeps anything sieging it within range. Also I make sure my next farthest defense is within the firing range of his neighbors. So no matter where the enemy may be they are most likely getting hit by two turrets at once.

I'm not really surprised - the maths alone would be a nightmare.

The thing about Newtonian mechanics is that, while there are always people who think they'd be a great idea, they're generally a complete pain in the unmentionables when it comes to gameplay.

Trying to calculate orbital mechanics, escape velocities and intercepts is hard enough for professional astronomers. I don't really want to get another degree in order to play a game.