What shape is the main equipment bus of each Voyager spacecraft?

The main equipment bus of each Voyager spacecraft is a decagonal prism—a ten-sided, three-dimensional structure.

The bus is the spacecraft’s central equipment housing. It contains engineering subsystems and supports major components such as the high-gain antenna, instrument platform, propulsion hardware, electronics, and the attachment points for booms and other equipment. NASA describes it more informally as a large ten-sided box.

The two Voyagers were designed as nearly identical twins, so both use the same basic decagonal bus geometry. The shape is not merely decorative: it provides a compact, rigid structure with multiple exterior sides for mounting equipment while enclosing the spacecraft’s electronics and other systems.

Images can make the bus look circular because the large dish antenna dominates the spacecraft’s profile. The spherical shape visible elsewhere belongs to a hydrazine fuel tank, not the main bus. Voyager’s ten-sided body is also distinct from the hexagonal bodies of the Pioneer spacecraft and the octagonal body used by Galileo.