Voyager 1 is the most distant human-made object in existence, having launched 44 years ago. It is currently operating at the edge of the solar system, flying through the “interstellar medium” beyond the Sun’s influence.
However, scientists found that the craft is receiving and executing commands from Earth successfully – but the readouts from the probe’s attitude articulation and control system (AACS) do not reflect what is actually happening on board Voyager 1.
The system maintains the craft’s orientation, keeping its antenna pointed precisely to the Earth so that data can be sent from it to Nasa. While all indications suggest that the AACS is working as normal, the telemetry data it is returning appears to be randomly generated – failing to reflect any possible state that the system could be in.
Further, the issue has not triggered any fault protection system that could put Voyager into safe mode, and the signal has not weakened – suggesting that the antenna is still in its normal position, pointing towards Earth.
Nasa says that it will continue to monitor the situation, as it is possible that the invalid data could be being produced by another system, but says that it does not understand why it is happening or how long this issue could continue. It takes approximately two days for a message from Earth to reach Voyager and get a response from the craft.
“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 Southern California.
“The spacecraft are both almost 45 years old, which is far beyond what the mission planners anticipated. We’re also in interstellar space – a high-radiation environment that no spacecraft have flown in before. So there are some big challenges for the engineering team. But I think if there’s a way to solve this issue with the AACS, our team will find it.”
There is a possibility that Nasa will not find the source of the issue and instead have to issue software changes or use one of the craft’s backup systems – something that has been done before in 2017 when Voyager had to switch from its primary thrusters to secondary ones because of signs of degradation.