NEW YORK (AP) — NASA has switched off another scientific instrument on its Voyager 2 spacecraft to save power.

The space agency said Tuesday the instrument that measures the flow of charged atoms was powered down so Voyager can keep exploring for as long as possible.

Four remaining instruments will continue collecting information about magnetic fields and particles as Voyager 2 drifts through interstellar space.

Launched in 1977 alongside its twin, Voyager 2 is the only spacecraft to visit Uranus and Neptune and is currently more than 12 billion miles from Earth.