A skybase was an orbital command centre used by the Earth Empire. Skybases were modular constructs, used in various forms for over three hundred years. They were linked to the planet below via transmat, and functioned as an orbital docking hub for starships.
Chris Cwej and Nyssa intercepted a load of fusion bombs aboard a skybase orbiting an Earth Empire colony in the 27th century. (PROSE: Cold Fusion)
The Earth Empire Overlords of the planet Solos were based on Skybase One in the 30th century. (TV: The Mutants)