The orbital layer is dependent on the ground layer. Your airspace is useful to you but not so much for someone else, and airspace over neutral ground doesn't do much at all, so why fight over it? Getting more territory is good for you, but gaining more airspace is really only useful if you own the land beneath it. You can cover enemy airspace to block them from using it with tacnets but they cost maintenance and resources so why do that unless your at war? For the orbital layer to be a second place to compete you need to be able to gain from it even if you don't own what's underneath it. Have the solar collector gain 30% of a city's energy for the empire that owns the orbital, not the city. That way you could put collectors in someone else's territory and eat their lunch. Weather controlers if outside your work range could function as weather research satellites and give science for each bonus resource underneath. Or make a new class of invasive but non hostile orbitals.