The Voyager probes, humanity’s most distant emissaries, are back in the headlines after a potential communication loss with Voyager 1 in December 2023. NASA reported that the spacecraft’s flight data system, comprising three onboard computers, began transmitting what seemed like binary gibberish—a string of ones and zeros—back to Earth, leaving engineers perplexed. While engineers could still send signals and confirm the probe’s operational status, something was clearly amiss.

Initially, NASA engineers attempted to reboot the system, but the strange data persisted. After months of trial and error, they finally found a solution that brought the probe back online. To fully understand the challenge, we must first appreciate the sheer scale of Voyager 1’s mission and the technical marvel that it represents.

Launched in September 1977, Voyager 1 was never meant to last this long. Originally designed for a four-year mission, the probe has now been traveling through space for nearly 47 years—an unimaginable duration for any spacecraft. Its twin, Voyager 2, was launched just weeks earlier, and together, they are the oldest active space probes in history. NASA’s goal now is to keep these probes operational for as long as possible, especially with their 50th anniversary approaching.

When the communications issue arose, engineers feared the worst. After all, Voyager 1 had already accomplished scientific feats that were beyond their wildest expectations. It revealed that Jupiter’s moon Io wasn’t just a barren rock, but a geologically active world with erupting volcanoes. The probe’s photos of Saturn and its largest moon, Titan, which might harbor liquid water, were equally groundbreaking. These discoveries, among many others, cemented Voyager 1’s place as one of the most important spacecraft ever built.

So, what caused the glitch? Engineers discovered that 3% of Voyager 1’s flight data system memory had become corrupted. This system, which manages the probe’s functions, is crucial for its autonomous operations, especially as Voyager 1 is currently over 15.5 billion miles from Earth. The cause of the malfunction could have been space radiation or simply the age of the probe. Unable to fix the faulty chip, engineers cleverly reallocated the corrupted code into spare memory sections, and after sending the first fix in April 2024, they received a successful response after a two-day wait.

This fix is just the beginning. Engineers now have to rewrite the rest of the lost code to restore the probe’s ability to send back important scientific data. However, even with these ongoing challenges, the Voyager probes continue to provide invaluable information about deep space. Despite their advanced age, both Voyager 1 and 2 are still transmitting data, although only a fraction of their original instruments are still operational.

NASA has been forced to shut down non-essential systems, like heaters, to conserve power for the high-gain antenna, which remains the primary communication link with Earth. Still, key instruments like the magnetometers, which study the Sun’s magnetic fields, and the particle instruments, which helped locate the heliopause (the boundary of our solar system), continue to function. Even the propulsion systems and micrometeorite shields are active, keeping the probes safe and operational.

However, the day will eventually come when both spacecraft cease to function. Their power sources, radioisotope thermoelectric generators, which use plutonium-238 to power the probes, are gradually losing their strength. When they finally stop, the Voyager missions will conclude. But their silence won’t render them useless. Both probes carry a message for any advanced civilizations that might one day discover them.

The Voyager Golden Records, which are mounted on both spacecraft, contain sounds, music, and images that provide a snapshot of life on Earth. Among the recordings are natural sounds like bird songs, greetings in 55 languages, and musical pieces ranging from Bach to Chuck Berry’s Johnny B. Goode. These golden records were designed to withstand the harshness of space for billions of years, providing a potential bridge for future extraterrestrial civilizations to learn about humanity.

In a fascinating twist, the ongoing communication with the Voyager probes is partly due to Earth’s orbit. As Earth moves around the Sun, it periodically approaches the spacecraft, temporarily reducing their distance. During these times, the probes get a little closer to Earth, allowing for a more efficient exchange of data.

As they continue their journey through interstellar space, the Voyager probes remain the farthest human-made objects from Earth, operating beyond the influence of the Sun’s solar wind. They are a testament to the ingenuity and perseverance of human exploration, and their journey is far from over. Despite the inevitable end of their mission, the data they have provided, and the message they carry, will resonate for generations to come.