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 navigate interstellar space. Traveling at about 38,000 mph relative to the Sun, Voyager 1 is currently the most distant human object. It is a technological marvel that has been whizzing around planetary orbits and sending useful information for almost 50 years. However, in November 2023, the 46-year-old spacecraft became stuck in a loop and began sending mysterious signals in the form of meaningless, unreadable data. After months of encoding and decoding, NASA announced in April 2024 that it had started sending readable data again for the first time since the error.

“Today was a great day for Voyager 1,” said Linda Spilker, JPL’s Voyager project scientist, according to CNN. “We’re back in touch with the spacecraft. And we’re looking forward to getting the science data back.” Call it coincidence or engineering that Voyager is now hurtling into interstellar space, far beyond Pluto’s orbit. The problem in question was solved after a series of trials and errors that the engineers carried out after discovering that the mystery of the malfunction lay in a single chip embedded in the spacecraft’s memory.

When the glitch was first discovered, engineers could tell from mission control that Voyager was still receiving their commands and operating normally, but the nonsense data kept coming in. In March 2024, engineers reported that the fault came from one of the three on-board computers, called the Flight Data Subsystem (FDS). FDS is responsible for packaging scientific and technical data before sending it to Earth in binary code format.

While searching the subsystem, the team dug up the root cause of the failure – a single chip located in the FDS memory. They concluded that the chip was damaged beyond repair. So they planned to put the affected code elsewhere in the FDS memory. But the place had to be big enough to hold this code, and there was no such place they could make up.

So they made something out of the box. They split the code into small segments and stored each segment in a different part of the FDS. After this process, they also needed to edit and organize all these code segments to work as a whole. Additionally, all references to the previous location of this code had to be updated on all systems.

After implementing this procedure, the team reported in April 2024 that they had moved the code to a new location in FDS memory. After that, all they had to do was wait for some time. It takes about 22½ hours for the radio signal to reach Voyager 1 and another 22½ hours for the signal to return to Earth. Their wait proved fruitful, as on April 20 the mission’s flight team reported receiving a legible signal from the spacecraft. Their command worked. The team also promised to fix other parts of the FDS memory to make the system work even more efficiently.

Voyager 1, launched in the summer of 1977, was designed with its twin, Voyager 2, to explore and obtain information about Saturn and Jupiter, Saturn’s rings, and the moons of both planets. Equipped with the Deep Space Network (DSN), the global spacecraft tracking system, the probe was expected to return valuable data, which it has done for decades using its highly sophisticated communications systems. The craft is equipped with instruments to perform 10 different experiments.

The instruments include television cameras, infrared and ultraviolet sensors, magnetometers, plasma detectors and cosmic ray, radio and charged particle sensors, not to forget the sentimental Golden Plate. The intelligent spacecraft is also equipped with a feature called “Radioisotope Thermoelectric Generators (RTGs)” that converts the heat produced 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 health, engineers are intrigued by the prospects it offers for deeper space exploration. “We never know for sure what will happen to the Voyagers, but it continues to amaze me that they keep going,” Voyager project manager Suzanne Dodd told CNN. “We’ve had many anomalies and they’re getting harder. But so far we have been lucky to recover from them. And the mission continues. And younger engineers are coming into the Voyager team and contributing their knowledge to sustaining the mission.”