Iconic Voyager spacecraft are powering down for good after 45 years

Voyager 1 and 2 were launched into space on September 5th, 1977, and August 20th, 1977, respectively.

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Credit: Graphic by Matthew Twombly and Juan Velasco (5W Infographic); Consultants: John Richardson (principal investigator, Voyager Plasma Science, Massachusetts Institute of Technology, Center for Space Research) and Merav Opher (professor, Department of Astronomy, Boston University)

Both Voyager spacecraft have identical designs, and both have reached interstellar space, the first human-made objects to do so. Almost 45 years later, they are still in service, returning data to Earth from beyond the solar system. This makes the Voyager spacecraft the longest-lasting spacecraft in history after initially only being designed for a four-year mission.

"The amount of software on these instruments is slim to none. There are no microprocessors-they didn't exist! On the whole. I think the mission lasted so long because almost everything was hardwired. Today's engineers don't know how to do this. I don't know if it's even possible to build such a simple spacecraft [now]. Voyager is the last of its kind," said Stamatios Krimigis, who designed the Voyager's Low-Energy Charged Particle (LECP) detector system.

Each Voyager launched with ten different scientific instruments, but Voyager 2 only has five still functioning, while Voyager 1 has four. They are all powered by electricity converted from heat generated by the radioactive decay of plutonium in their radioisotope thermoelectric generators (RTGs).

Power output is slowly decreasing by roughly four watts per year, leading NASA engineers to turn off instruments one by one to extend the spacecrafts' life. Even still, the Voyager spacecraft remain valuable, and have returned data to enable a new study published in the The Astrophysics Journal on June 15th, 2022.

"If everything goes really well, maybe we can get the missions extended into the 2030s. It just depends on the power. That's the limiting point," said Linda Spilker, a NASA Jet Propulsion Laboratory (JPL) planetary scientist who started working on the Voyager missions in 1977, a few months before their launch.

Check out this article in Scientific American for more information on this story.

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Credit: Graphic by Matthew Twombly and Juan Velasco (5W Infographic); Consultants: John Richardson (principal investigator, Voyager Plasma Science, Massachusetts Institute of Technology, Center for Space Research) and Merav Opher (professor, Department of Astronomy, Boston University)