They lacked the idea of a traditional nation-state, but remained cohesive still, and the few worlds they had permanently settled were industrial powerhouses, funded by automated mining operations that imported valuable resources from nearby systems.
I've always been enchanted by the idea of polities that exist despite not being true nation-states so this caught my eye. On another note, the motto "Ever Vigilant" was almost my choice here but I decided it was probably best to go for something more substantial.