Voyager 1, the world’s most faraway space probe, is sending back weird signals. is calling the mysterious set of signals a “telemetry issue,” and experts say it shouldn’t be surprising that an interstellar ship launched 45 years ago would start getting a little confused about where it is and which way it’s heading:

“A mystery like this is sort of par for the course at this stage of the Voyager mission,” Suzanne Dodd, project manager for Voyager 1 and its twin, Voyager 2, at NASA’s Jet Propulsion Laboratory in California, said in a statement.

“The spacecraft are both almost 45 years old, which is far beyond what the mission planners anticipated,” Dodd added. “We’re also in interstellar space — a high-radiation environment that no spacecraft have flown in before.”

The glitch has to do with Voyager 1’s attitude articulation and control system, or AACS, which keeps the spacecraft and its antenna in the proper orientation. And the AACS seems to be working just fine, since the spacecraft is receiving commands, acting on them and sending science data back to Earth with the same signal strength as usual. Nevertheless, the AACS is sending the spacecraft’s handlers junk telemetry data.

The twin Voyager 2 probe, also launched in 1977, is behaving normally, NASA said.

You can read the full NASA statement here.