NASA has deactivated one of Voyager 2’s science instruments as the spacecraft’s power levels continue to decline. Launched in 1977, Voyager 2 is currently more than 12.8 billion miles (20.5 billion kilometers) from Earth, exploring the interstellar medium beyond the heliosphere, the outermost layer of the Sun’s influence. While still functioning, the spacecraft is powered by slowly decaying plutonium, leading to gradual reductions in the energy available to operate its systems. The Decision to Power Down Voyager 2The deactivated instrument is the plasma science instrument, one of the key tools…