“Mission engineers at NASA’s Jet Propulsion Laboratory in Southern California turned off the cosmic ray subsystem experiment aboard Voyager 1 on Feb. 25 and will shut off Voyager 2’s low-energy charged particle instrument on March 24. Three science instruments will continue to operate on each spacecraft. The moves are part of an ongoing effort to manage the gradually diminishing power supply of the twin probes. Launched in 1977, Voyagers 1 and 2 rely on a radioisotope power system that generates electricity from the heat of decaying plutonium. Both lose about 4 watts of power each year,” says a NASA update on the nearly half-century-old probes.
“‘The Voyagers have been deep space rock stars since launch, and we want to keep it that way as long as possible,’ said Suzanne Dodd, Voyager project manager at JPL. ‘But electrical power is running low. If we don’t turn off an instrument on each Voyager now, they would probably have only a few more months of power before we would need to declare end of mission.”
It’s not clear what if any new discoveries or insights about outer space the Voyager probes are still making as they drift out into the interstellar void or if the whole point of keeping them active is to be able to say they’re still active. Maybe NASA should just come clean and say that if so.