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.

Nearly 50 years after they were first launched, Voyager 1 and 2 are still traveling around interstellar space — though they've faced some setbacks over the years. Now, NASA has announced that the twin Voyager spacecraft are losing some of their features in a bid to extend their lifespans in the face of a diminishing power supply.

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.