NASA scientists have found a way to extend the working life of a science instrument on Voyager 2 by managing the spacecraft’s dwindling power supply more efficiently. The change matters because Voyager 2 is one of only two probes operating in interstellar space, where its measurements provide rare data about the boundary of the Sun’s influence and the surrounding environment.

Launched in 1977, Voyager 2 was more than 12 billion miles from Earth and running five science instruments. Its power supply declines as its plutonium-based generator produces less electricity, but the new strategy was expected to delay the next instrument shutdown until 2026 rather than 2023, allowing additional years of observations.