Ones and zeros. That’s the love language of computers. It’s how NASA’s long-lived Voyager 1 spacecraft communicates with its team back on Earth. Voyager 1 is still talking to NASA, but it’s not making much sense after a glitch impacted one of its onboard computers.

The computer in question is the flight data system. The FDS isn’t communicating properly with the spacecraft’s telecommunications unit. “As a result, no science or engineering data is being sent back to Earth,” NASA said in a statement on Tuesday. The FDS pulls data from Voyager 1’s science instruments and also monitors the health of the spacecraft. It hands that data off to the probe’s telecommunications unit, known as the TMU, to be sent home.

The Voyager 1 team became aware of a glitch when the TMU began to send back a repeating pattern of ones and zeros. NASA said it seemed like the TMU was “stuck.” Engineers tried a simple fix first: turn it off and turn it back on again. The team attempted to restart the FDS in hopes it would return to a functioning state. It didn’t work. That means NASA will now have to engage in a more involved troubleshooting process.

Voyager 1 launched in 1977 and spent decades exploring our solar system before crossing into interstellar space in 2012. The original mission was meant to last four years as the probe visited Jupiter and Saturn. It’s now spent 46 years in space, making Voyager 1 and its twin Voyager 2 the longest-operating spacecraft in history. Both explorers are sending back valuable data on their interstellar surroundings. Sometimes it’s downright poetic, as when Voyager 1 detected the “gentle rain” of vibrating interstellar plasma.

There are many challenges with maintaining Voyager 1’s operations. The spacecraft is far, far away. Sending a command to the probe takes 22.5 hours as the data traverses over 15 billion miles of distance. It takes just as long for Voyager 1 to send back an answer and for the team to know if the command worked.