Jupiter

Ruler of the skies, now in fact and not just in name. Governed by the Jovian Consortium Corporate Council.

The Jupiter Sphere technically includes over 100 moons, most of which are uninhabited. The main four, Io, Europa, Callisto, and Ganymede are all inhabited, with resources extracted from Europa forming the backbone of the Sphere's ability to sustain life.

Jupiter's magnetosphere, on top of its many more obvious environmental pressures, makes mining it incredibly dangerous and forces significant design compromises to be able to operate any machinery whatsoever inside it for long.