All of the spacecraft's power is generated, stored and distributed by the electrical power subsystem. The system obtains its power from an array of gallium arsenide solar cells. A power distribution and drive unit contains switches that send power to various loads around the spacecraft. Power is also stored in a 16-amp-hour nickel hydrogen battery.
The electrical power subsystem operates the gimbal drives on the high-gain antenna and the solar array. It contains also a pyro initiator unit, which fires pyrotechnically actuated valves, activates burn wires, and opens and closes thruster valves.
The electrical power subsystem weighs 86.0 kilograms (189.6 pounds).