How NASA found an ingenious way to bring Voyager 1 back to life

Flying more than 15 billion miles from Earth, Voyager 1 is the first man-made object to travel in interstellar space. Traveling at about 38,000 miles per hour relative to the Sun, Voyager 1 is currently the farthest man-made object. It is a technological marvel that has been whizzing through planetary orbits for nearly 50 years, sending useful information. However, in November 2023, the 46-year-old spacecraft got stuck in a loop and began sending eerie signals in the form of incomprehensible, unreadable data. After months of encoding and decoding, NASA reported in April 2024 that it had begun sending readable data for the first time since the glitch.

“Today was a great day for Voyager 1,” Linda Spilker, Voyager project scientist at JPL, said, according to CNN. “We’re back in contact with the spacecraft. And we’re excited to get science data back.” Call it a happy coincidence or the work of engineers that Voyager is now hurtling into interstellar space, well beyond the orbit of Pluto. The problem in question was fixed after a series of trials and errors after engineers discovered that the secret to the failure lay in a single chip embedded in the spacecraft’s memory.

When the error was first discovered, engineers were able to tell mission controllers that while Voyager was still receiving their commands and functioning normally, the data was still coming in nonsense. In March 2024, engineers announced that the error came from one of the three onboard computers, called the Flight Data Subsystem (FDS). The FDS is responsible for bundling the scientific and engineering data before sending it to Earth in a binary code format.

The team searched the subsystem and found the cause of the failure – a single chip in the FDS memory. They concluded that the chip was damaged and not repairable, so they planned to place the affected code elsewhere in the FDS memory. However, the location had to be large enough to accommodate this code, and they could not think of a suitable location.

So they did something unconventional. They split the code into very small segments and stored each segment in a different part of the FDS. After this process, they also had to adapt and organize all of these code segments so that they could work as a whole. They also had to update all references to the previous location of this code in all systems.

After completing this procedure, the team announced in April 2024 that they had transferred the code to its new location in the FDS memory. After that, they just had to wait a while. A radio signal takes about 22½ hours to reach Voyager 1 and another 22½ hours to return to Earth. Their wait proved fruitful, because on April 20, the mission flight team reported receiving a readable signal from the spacecraft. Their command had worked. The team also promised to repair the other parts of the FDS memory so that the system could work even more efficiently.

Voyager 1 was launched in the summer of 1977 along with its twin Voyager 2 and was designed to explore and collect information about Saturn and Jupiter, Saturn’s rings and the moons of both planets. Equipped with the Deep Space Network (DSN), a global spacecraft tracking system, the probe was designed to provide valuable data, which it did for decades thanks to its sophisticated communications systems. The spacecraft is equipped with instruments to conduct ten different experiments.

Instruments include television cameras, infrared and ultraviolet sensors, magnetometers, plasma detectors, and cosmic ray, radio and charged particle sensors, not to mention the soulful Golden Record. The intelligent spacecraft is also equipped with a feature called radioisotope thermoelectric generators (RTGs), which convert heat generated by the natural radioactive decay of plutonium into electricity to power the spacecraft’s instruments, computers, radios and other systems.

Now that the spacecraft is back in good working order, engineers are intrigued by the prospects it offers for exploring deeper parts of space. “We never know exactly what’s going to happen with the Voyagers, but it always amazes me when they just keep going,” Voyager project manager Suzanne Dodd said, according to CNN. “We’ve had a lot of anomalies and they’re getting worse. But we’ve been lucky so far to recover from them. And the mission continues. And younger engineers are coming onto the Voyager team and contributing their knowledge to keep the mission going.”