For about 5 months, experts have been tirelessly working to fix issues and restore communication with Voyager 1, a spacecraft that has been operational for nearly half a century.
After five months of efforts to re-establish contact with the farthest human-made object, NASA announced that the Voyager 1 spacecraft finally “called home” on April 20. For the engineers and scientists involved in NASA’s longest-running space mission, it was an incredibly relieving and exhilarating moment.
Simulation of the Voyager 1 spacecraft entering interstellar space.
“That Saturday morning, all of us gathered around boxes of donuts, waiting for data to come in from Voyager. We knew exactly when it would happen; it was all very quiet, with everyone just sitting there staring at the screen,” recalled Linda Spilker, a scientist on the Voyager 1 mission at NASA’s Jet Propulsion Laboratory (JPL).
When the spacecraft finally responded to the call, the room erupted with celebration. “There were cheers, everyone raised their hands, and there was a sense of relief. After all the hard work, from the near impossibility of receiving signals from Voyager to re-establishing communication, it was a huge relief and an amazing feeling,” Spilker shared.
The problems with Voyager 1 were first detected in November of last year. At that time, NASA was still able to communicate with the spacecraft and could see that it was receiving signals from Earth. However, what was being sent back to the control station—including scientific data, health status information, and system reports—was distorted and unreadable. This initiated a “battle” lasting several months to determine what had gone wrong and to save Voyager 1.
Spilker and her colleagues remained hopeful and optimistic, but they faced significant challenges. First, engineers had to troubleshoot while the spacecraft was moving through interstellar space, over 24 billion kilometers from Earth.
Voyager team members celebrating in the workshop at NASA’s Jet Propulsion Laboratory (JPL) on April 20. (Photo: NASA)
“For Voyager 1, it takes 22.5 hours to send a signal out and another 22.5 hours to receive a response. So, we prepared commands, sent them out, and about two days later would find out if they were effective,” Spilker explained.
Ultimately, the team identified that the issue originated from one of the three computers onboard the spacecraft. Spilker indicated that a hardware failure—likely due to age or radiation—may have corrupted a segment of code in the computer’s memory. This malfunction prevented Voyager 1 from transmitting clear information related to its health and scientific observations.
NASA engineers concluded that they would not be able to repair the damaged software storage chip. The faulty code was also too large for Voyager 1’s computer to store alongside any new instructions sent to it. Given that the technology on Voyager 1 dates back to the 1960s and 1970s, its memory is less capable than that of today’s smartphones. Spilker noted that it is roughly equivalent to the internal memory capacity of an electronic car key.
Eventually, the experts found a solution. They divided the code into smaller parts and stored them in different areas of the computer’s memory. After that, they reprogrammed the necessary segments while ensuring that the entire system continued to function smoothly. This was a remarkable feat, as Voyager 1 was built long ago and there was no testing platform or simulation equipment on Earth to validate new code segments before sending them to the spacecraft.
“Three people reviewed every line of the code we intended to send, looking for anything that might have been overlooked. It was like a visual inspection,” Spilker said. This painstaking work ultimately yielded valuable results, restoring communication with Voyager 1.
As of now, the research team has determined that Voyager 1 is still in good condition and operating normally, NBC News reported on April 27. Spilker indicated that the spacecraft’s scientific instruments are still powered on and seem to be functioning, but it will take some time before the spacecraft resumes transmitting scientific data.
Titan/Centaur-6 launch vehicle carrying Voyager 1 from Kennedy Space Center on September 5, 1977. (Photo: NASA)
Voyager 1 and its “twin” Voyager 2 were launched into space in 1977 with the mission to explore the outer regions of the Solar System. According to Spilker, the spacecraft may continue to operate until the 2030s. Eventually, they will either run out of power or their components will become too old to function.
The day that Voyager 1 and 2 must cease operations will be a very difficult day, but they will continue to exist as “silent ambassadors.” Both spacecraft carry valuable messages on the Golden Record. The records contain images and sounds representing life on Earth and human culture, including music, animal sounds, laughter, and greetings recorded in many languages. The duo of spacecraft will carry these messages until they are discovered by future space travelers.
“Perhaps in about 40,000 years, they will come close to another star. At that time, they may be found,” Spilker said.
