Voyager 1 continues to perform well, despite its advanced age and its distance of 14.5 billion miles (23.3 billion kilometers) from Earth. And it can receive and execute commands sent by NASA, as well as collect and send back scientific data.
But the readings from the articulation and attitude control system, which control the spacecraft’s orientation in space, don’t match what Voyager is actually doing. The Attitude and Articulation 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 calling and replying a message between NASA and Voyager takes two days.
So far, the Voyager team thinks the AACS is still working, but data readings from the instrument seem random or impossible. So far, the system glitch hasn’t triggered anything to put the spacecraft into “safe mode.” This is when only essential operations occur so engineers can diagnose a problem that would put the spacecraft in danger.
And Voyager’s signal is stronger than ever, meaning the antenna is still pointed at Earth. The team is trying to determine if this incorrect data comes directly from this instrument or if another system is the cause.
“Until the nature of the problem is better understood, the team cannot predict whether this could affect how long the spacecraft can collect and transmit science data,” according to a NASA statement.
“A mystery like this is somewhat normal at this point in the Voyager mission,” Suzanne Dodd, project manager for Voyager 1 and 2 at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., said in a statement. .
“The spacecraft are both nearly 45 years old, which is far beyond what mission planners had anticipated. We are also in interstellar space – a high-radiation environment in which no spacecraft can ‘ve flown before. So there are big challenges for the But I think if there’s a way to fix that with AACS, our team will find it.”
If the team doesn’t determine the source of the problem, they can just adapt to it, Dodd said. Or if they can find it, the problem can be solved by modifying the software or relying on a redundant hardware system.
Voyager has relied on backup systems before to last as long as it has. In 2017, the probe fired thrusters that were used in its first planetary encounters in the 1970s – and they were still working after sitting unused for 37 years.
Aging probes produce very little power per year, so subsystems and heaters have been turned off over the years so that critical systems and scientific instruments can continue to function.
Voyager 2, a sister spacecraft, continues to perform well in interstellar space 19.5 billion kilometers from Earth. In comparison, Neptune, the furthest planet from Earth, is at most only 2.9 billion kilometers away. Both probes were launched in 1977 and far exceeded their original goal of flying past planets.
Now they have become the only two spacecraft to collect data from interstellar space and provide information about the heliosphere, or the bubble created by the sun that extends beyond the planets of our solar system.