Mystery issue experienced on NASA’s Voyager 1 probe from 1977

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The Voyager 1 probe is still exploring interstellar space 45 years after launching, but it has encountered an issue that mystifies the spacecraft’s team on Earth.

Voyager 1 continues to operate well, despite its advanced age and 14.5 billion-mile distance (23.3 billion kilometers) from Earth. And it can receive and execute commands sent from NASA, as well as gather and send back science data.

But the readouts from the attitude articulation and control system, which control the spacecraft’s orientation in space, don’t match up with what Voyager is actually doing. The attitude articulation and control system, or AACS, ensures that the probe’s high-gain antenna remains pointed at Earth so Voyager can send data back to NASA.

Due to Voyager’s interstellar location, it takes light 20 hours and 33 minutes to travel one way, so the call and response of one message between NASA and Voyager takes two days.

So far, the Voyager team believes the AACS is still working, but the instrument’s data readouts seem random or impossible. The system issue hasn’t triggered anything to put the spacecraft into “safe mode” so far. That’s when only essential operations occur so engineers can diagnose an issue that would put the spacecraft at risk.

This artist's concept depicts NASA's Voyager 1 spacecraft entering interstellar space, or the space between stars. Interstellar space is dominated by the plasma, or ionized gas, that was ejected by the death of nearby giant stars millions of years ago. The environment inside our solar bubble is dominated by the plasma exhausted by our sun, known as the solar wind. The interstellar plasma is shown with an orange glow similar to the color seen in visible-light images from NASA's Hubble Space Telescope that show stars in the Orion nebula traveling through interstellar space. The Voyager spacecraft were built and continue to be operated by NASA's Jet Propulsion Laboratory, in Pasadena, Calif. Caltech manages JPL for NASA. The Voyager missions are a part of NASA's Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission Directorate at NASA Headquarters in Washington. Image Addition Date: 2013-09-12

Voyager spacecraft detects 'persistent hum' beyond our solar system

And Voyager’s signal is as strong as ever, meaning the antenna is still pointed to Earth. The team is trying to determine if this incorrect data is coming directly from this instrument or if another system is causing it.

“Until the nature of the issue is better understood, the team cannot anticipate whether this might affect how long the spacecraft can collect and transmit science data,” according to a NASA release.

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