March 5 (UPI) -- Engineers at NASA's Jet Propulsion Laboratory have conserved energy supplies on the record-setting Voyager 1 & 2 deep space probes nearly 50 years after their missions launched to extend them further. NASA launched the probes in 1977, which rely on a diminishing radioisotope power system that uses the heat from decaying plutonium to generate electrical power. Advertisement Each probe loses about 4 watts of power every year, but NASA has extended their respective missions by