Saving Voyager: NASA's Race Against Time in Interstellar Space.

NASA's Voyager spacecraft, which are the oldest running and farthest flung machines of humanity, are still going strong in interstellar space thanks to the ingenuity of scientists operating them from the ground. The spacecraft are equipped with Radioisotope Thermoelectric Generators (RTGs) that generate electrical power from the heat produced by the decay of Plutonium-238. As the fuel decays, the available power declines, and NASA scientists have had to come up with creative solutions to keep Voyager 1 and 2 in action, including cutting power to the heating systems and allowing the craft to dip into reserve power meant to protect them from voltage spikes.