Voyager 1 is in trouble. The engineering team with NASA’s Voyager 1 spacecraft is trying to solve a mystery: readouts from the probe’s attitude articulation and control system (AACS) don’t reflect what’s actually happening onboard. The AACS controls the 45-year-old spacecraft’s orientation. Among other tasks, it keeps Voyager 1’s high-gain antenna pointed precisely at Earth, enabling it to send data home. All signs suggest the AACS is still working, but the telemetry data it’s returning is invalid. For instance, the data may appear to be randomly generated or does not reflect any possible state the AACS could be in. The issue hasn’t triggered any onboard fault protection systems, which are designed to put the spacecraft into “safe mode” – a state where only essential operations are carried out, giving engineers time to diagnose an issue. Voyager 1’s signal hasn’t weakened, either, which suggests the high-gain antenna remains in its prescribed orientation with Earth. While the engineers continue to work at solving the mystery that Voyager 1 has presented them, the mission’s scientists will continue to make the most of the data coming down from the spacecraft’s unique vantage point.