The Dea Dia System discovery research require the Rocket Turret tech, but there is no space lane that would actually require the rocket turret until you travel to Jarbid, or to Mirandus-A within the Metal and Stars system. The techs and space lanes also lock the Metal and Stars system behind Dea Dia system, and therefore behind Metallurgic, Electromagnetic, and Biological sciences, putting it almost on the same tier of research difficulty as Aquilo, when I believe it is intended to be accessible earlier.

That is the normal requirements for Dea Dia. I did not change them. I only added the "Core System Travel" also as a requirement.

I did actually miss that Dea Dia required rockets to access though. But all of the Metal and Stars planets except for the Shipyard should require rockets because they have big asteroids so I am on the fence if I should change it. The Shipyard, on its own, is not that useful without one of the other 3 planets.

Neumann and Circa both only have medium asteroids, it is only Mirandus and Nix that have Big asteroids.