The high demand for hydrogen and helium-derived fuel during the initial phases of human expansion to other planets caused Jupiter's mining corporations to sky-rocket in power and influence. These days Jupiter has been eclipsed by other suppliers, but it is still a hub for mining and fabrication conglomerates without the cash to establish themselves in the Kuiper belt.
One of the more uninteresting moons in Jupiter's vast swathe of satellites, Europa underwent several abortive and abandoned colonisation attempts, most famously the Yonaguni disaster that resulted in the collapse of several colony domes and the lonely deaths of thousands of people. More information So-far unexplained signal disturbances render the moon far more remote than mere distance would account for, but a handful of colonists and corporate research bodies still inhabit the desolate place.
A once-bustling facility servicing the Europa colonies; now largely abandoned other than automated systems and once-a-year maintenance crews.
Due to its size and magnetosphere, Ganymede came to house the majority of the facilities constructed during Jupiter's exploitation. The abundant water and silicates, combined with geologically stability, made it an ideal base of operations for the fuel refining companies and their workers. Much of Jupiter's bounty was packaged and shipped from Ganymede, and it rapidly gained a relatively huge population despite significant population and capital loss following a fuel crash towards the end of human expansion. Ganymede is still home to millions of people, facilities and data havens, and several engineering and technical universities have established themselves there.
Largely unimportant in terms of resource exploitation and uninteresting for civilian uses, Callisto was claimed by the central government shortly after it became economically feasible to construct facilities there. The orbit of this moon rapidly became host to immense numbers of habitat modules, maintenance shipyards and naval bases. Today, Callisto is called 'The barracks of Sol', as most of the system fleet is housed there; the orbital habitats are predominantly populated by naval officers, marines and their families.