NASA shut down Voyager 1's Low-energy Charged Particles instrument on April 17 after nearly 49 years of continuous operation to preserve the spacecraft's dwindling power supply — the probe loses about 4 watts per year from its plutonium-fueled reactor. The shutdown buys the mission roughly a year while engineers test a major power-conservation upgrade called 'the Big Bang,' which could extend Voyager 1's operations further and possibly restore the LECP later. Voyager 1 remains the only human-made object in interstellar space and still carries two working science instruments measuring plasma waves and magnetic fields from a region no other spacecraft has reached.