It’s been 47 years since the twin Voyager spacecraft started their historic mission. Having travelled through interstellar space, farther from Earth than any other human-made objects, their nuclear batteries are depleting — but NASA is taking measures to squeeze as much life out of the aging probes as possible.

However, NASA isn’t ready to say goodbye just yet, and is taking measures to get as much life out of the pair as possible. On March 5, Voyager mission engineers at the Jet Propulsion Laboratory in southern California confirmed they have already turned off Voyager 1’s cosmic ray subsystem experiment.

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.