NASA reveals new plans to extend Voyager missions

Launched in 1977, the Voyager probes are the longest-serving spacecraft in history, capturing data from Jupiter, Saturn, Neptune and Uranus before continuing their journeys beyond the heliosphere to interstellar space. Voyager 1 is now almost 22 billion km from the Sun, while its sibling is a mere 18 billion km.

Each of the probes is powered by three radioisotope thermoelectric generators, or RTGs, which produce heat via the natural decay of plutonium-238 radioisotopes and convert that heat into electrical power. Because the heat energy of the plutonium in the RTGs declines and their internal efficiency decreases over time, each spacecraft is producing about 4 fewer watts of electrical power each year. That means the generators produce about 40 per cent less than at the time of launch nearly 42 years ago, limiting the number of systems that can run on the spacecraft.

The mission's new power management plan explores multiple options for dealing with the diminishing power supply on both spacecraft, including shutting off additional instrument heaters over the coming years.