Last month, NASA briefly lost Voyager 1 in the expanse of interstellar space, and when the craft reappeared it was communicating with a transmitter it hasn’t used in more than 40 years. NASA is now troubleshooting the issue.
The trouble began on October 16, when NASA beamed a command to Voyager 1 to turn on one of its heaters. An innocent enough request, but the spacecraft responded by ghosting Earth.
It actually took the agency two full days to notice the issue. That’s because Voyager 1 is the most distant human-made object, and being almost 25 billion kilometers (15.3 billion miles) away, it takes nearly 23 hours for a message to get there – even at the speed of light – and another 23 hours for a response.
On October 18, Voyager 1 missed its scheduled return call. NASA’s Deep Space Network (DSN) scanned for the signal and eventually found it on a slightly different frequency band.
It seems that the heater triggered Voyager 1’s built-in fault protection system. If an instrument tries to draw too much power, this mechanism will automatically shut off other, non-essential systems to conserve energy.
In this case, the casualty was its X-band radio transmitter, the spacecraft’s main line of communication with Earth. To save power, the fault protection system had reduced the rate of data transmission, and changed the X-band signal.
DSN reestablished the connection, and things seemed stable while the flight team began investigating the issue. But the next day, comms cut out completely.
NASA’s suspicion is that the X-band transmitter had set off the fault protection system twice more, which would have caused the craft to turn it off completely. In its place, Voyager 1 would have switched to the S-band transmitter, which uses less power.
Unfortunately, it’s also far fainter, and the crew feared that it could no longer be detected from this far away. After all, Voyager 1 hasn’t used the S-band transmitter to talk to Earth since 1981, when it was obviously much, much closer to us.
Thankfully, DSN engineers were able to reconnect with this instrument, sending a command on October 22 that confirmed it’s still working. The team doesn’t want to turn the X-band transmitter back on before they can figure out what the problem is, but troubleshooting is ongoing. Hopefully, Voyager 1 will be returned to normal operations soon.
The most impressive part of the story is that it’s still possible to run these kinds of diagnostics from across the width of the solar system, on tech that’s almost 50 years old. Although, as they age, the Voyager probes are having more and more technical troubles.
In 2022, a glitch caused Voyager 1 to send back garbled telemetry data for a few months. And between November 2023 and June 2024, the probe sent back nothing but nonsense, which was eventually traced to a corrupted chip in its memory system.
It’s important to keep the two probes in working order, as they move through a region of space that no other human-made objects have yet experienced – interstellar space. There, beyond the Sun’s influence, the Voyager twins have made some intriguing discoveries.
Sadly, we might not have too much time left. Due to a dwindling power supply, it’s expected that they’ll stop collecting science data after 2025. By 2036, they’ll be out of range of the DSN, so we’ll likely lose track of them completely.
It might take them tens of thousands of years to exit the Oort Cloud, the icy structure that’s hypothesized to surround our solar system. In about 40,000 years’ time, both Voyagers are expected to zip within two light-years of neighboring stars.
After that, these little monuments to human ingenuity will continue to whizz through the darkness for eons, carrying what may end up being the final vestiges of human culture.
