What is the mass of a Voyager spacecraft at launch?

Each Voyager spacecraft had a launch mass of 815 kilograms. That figure includes the spacecraft structure, scientific instruments, electronics, propellant, communications hardware, and other equipment needed for its long journey through the outer Solar System.

Voyager’s design was built around a large high-gain antenna, a central electronics body, a movable science platform, and long instrument booms. The spacecraft also carried hydrazine propellant for attitude control and radioisotope thermoelectric generators to produce electricity far from the Sun. Scientific instruments accounted for about 105 kilograms of the launch mass.

The 815-kilogram figure describes the spacecraft at launch, not its current mass. As Voyager used propellant, its mass decreased to roughly 733 kilograms. The number can also be confused with the mass of an individual instrument or with later mission estimates that exclude fuel. Voyager 1 and Voyager 2 were nearly identical spacecraft, so the same launch-mass figure applies to both.