The Courageous is outbound from the Earth-Moon system, on an exploration mission to the asteroid belt. Its low thrust, high efficiency ion engines produce only a few hundredths of a G of acceleration, but it can thrust continuously for weeks, unlike rocket engines. A nuclear reactor supplies the electricity for the ion drive, to allow operations far beyond the Earth’s orbit, where solar cells can’t provide enough power. The reactor counterbalances the Habitat module on the far end of the boom. The whole ship spins around the engine/hub module, to produce half a gee of centrifugal force to the habitat.
The design is based on a NASA study, but the details are mine.
Rendered and modeled in Lightwave, with post work in Photoshop CS3.