NASA’s Voyager 1 probe, which has been traversing interstellar space, has once again begun sending intelligible radio signals to Earth. The spacecraft had been experiencing a computer glitch that rendered its data transmissions incomprehensible for five months.
Engineers have been working diligently to resolve the issue and have now successfully fixed the computer problem, allowing Voyager 1 to transmit usable data regarding the status of its onboard systems. However, the team is still working on fixing the software that will enable the spacecraft to resume transmitting scientific data.
Voyager 1, along with its twin probe Voyager 2 which continues to operate normally, was launched nearly 47 years ago and is among the most distant human-made objects in existence. The spacecraft is currently approximately 15 billion miles (24 billion kilometers) away from Earth, resulting in a 22.5-hour delay in communications.
The glitch was first detected on November 14, 2023, when Voyager 1 started transmitting an unintelligible string of ones and zeros instead of its usual structured data. While the probe continued to receive commands from Earth, indicating that its vital systems were operating normally, the data it sent back was unusable.
After thorough analysis, NASA engineering teams identified the problem as originating from the flight data subsystem (FDS), one of three onboard computer systems responsible for packaging data for transmission. The FDS is crucial for ensuring that the data collected by the probe is properly formatted before being sent to Earth.
To troubleshoot the issue, engineers sent a command to the FDS, prompting it to attempt different sequences of code in its software, hoping to bypass the corrupted section. This command triggered a response from the spacecraft, giving engineers a vital clue.
Further investigation revealed that a single chip responsible for storing a portion of the FDS memory, including computer software code, had malfunctioned. The loss of that code rendered the probe’s science and engineering data unusable.
To overcome this obstacle, the team split the code that was previously stored on the affected chip into smaller sections and distributed it among the remaining functioning memory portions of the FDS. They then rewrote parts of the rearranged code to ensure it would function as a cohesive whole. These modifications were saved to the FDS memory on April 18.
Two days later, the team received a response from Voyager 1 indicating that the code rearrangement had been successful. For the first time in five months, the probe’s transmission contained readable data, prompting celebration at the Jet Propulsion Laboratory in Southern California.
While the restoration of the probe’s data transmission is a significant milestone, NASA emphasizes that further repairs are needed to resolve the issue affecting the transmission of science data. The team is continuing to work on addressing the remaining corrupted portions of the FDS software, ensuring Voyager 1 can continue to transmit valuable scientific data from the depths of interstellar space.
