NASA's aging spacecraft taps backup power to continue exploring interstellar space

NASA's Voyager 2 spacecraft has been exploring interstellar space for more than 45 years, making it one of history's most durable and long-lasting space missions. To keep its science instruments operating despite a diminishing power supply, the veteran spacecraft has started using a small reservoir of backup power set aside as part of an onboard safety mechanism.

The new power strategy will keep Voyager 2's science instruments turned on for a few years longer than previously anticipated, the agency said in a statement on Wednesday.

"The science data that the Voyagers are returning gets more valuable the farther away from the Sun they go, so we are definitely interested in keeping as many science instruments operating as long as possible," said Linda Spilker, Voyager's project scientist at NASA's Jet Propulsion Laboratory in Southern California, which manages the mission for NASA.

Voyager 2 and its twin Voyager 1 are powered by radioisotope thermoelectric generators (RTGs) that generate electricity by converting heat from decaying plutonium. However, the generator produces slightly less power each year due to the decay process. Although this decline hasn't affected the mission's scientific output, engineers have shut down non-essential systems such as heaters to offset the power loss and keep the spacecraft operational.

To prevent the shutdown of a science instrument on Voyager 2, the team analyzed the safety mechanism that safeguards the instruments in case of significant voltage changes. The spacecraft has a voltage regulator that activates a backup circuit to prevent damage to the instruments. The circuit can access a limited amount of power from the RTG that's kept aside for such an event. Rather than keeping this power in reserve, the mission will now utilize it to keep the science instruments operating for a few more years.

Operating more than 12 billion miles (20 billion km) from Earth, @NASAVoyager 2 uses five science instruments to study interstellar space. To keep those instruments operating, the spacecraft has begun using a small reserve of backup power: https://t.co/ftEcZrDjd7 pic.twitter.com/0ILCjfOEkC

— NASA JPL (@NASAJPL) April 26, 2023