NASA's VOYAGER 1 spacecraft is on a perilous and unknown voyage into deep space. It and its sister probe, Voyager 2, are the most farthest human-made objects from our planet, having travelled beyond the Solar System's boundaries and into the interstellar medium. Anything can go wrong at such a distance. Add to that the fact that this is an ancient craft: The Voyagers first appeared in the 1970s. When Voyager 1 began sending back strange, garbled nonsense instead of telemetry data in May of this year, NASA engineers could have been forgiven for calling it a day and pouring one out for possibly the greatest successful space project of all time.
But that is not how NASA operates. Instead, they began work on a remote diagnosis and repair for the world-record-breaking spacecraft. They are now victorious, four months later. Voyager 1 has returned to service and is speaking with ground control as if nothing had happened. In truth, the solution was very easy — or as simple as anything can be with a 22-hour communications lag in either direction and billions of kilometres between.
WHAT BECOME OF VOYAGER 1?
NASA’S VOYAGER 1 is on a fraught and unknowable journey into deep space. Some 14.6 billion miles from Earth, it and its sister craft, Voyager 2, are the furthest human-made objects from our planet, having made it beyond the edges of the Solar System and out into the interstellar medium. At such distances, anything can go wrong. Add to that the fact that these are old craft: The Voyagers launched in the 1970s. So when Voyager 1 started to send home weird, garbled nonsense instead of telemetry data in May of this year, NASA engineers might have been forgiven for calling it a day and pouring one out for perhaps the most successful space mission of all time.
But that’s not how NASA works. Instead, they started working on a remote diagnosis and fix for the record-breaking spacecraft. Now, some four months later, they are triumphant. Voyager 1 is back online and communicating perfectly with ground control as if it never happened. In fact, the fix turned out to be relatively simple — or as simple as anything can be with a 22-hour communications lag in each direction and billions of miles of space in between.
WHAT HAPPENED TO VOYAGER 1?
The high-gain antenna seen on the left in this figure is how Voyager 1 communicates with NASA engineers on Earth.
The 45-year-old spacecraft appeared to be performing admirably in interstellar space, sending gobs of data back to Earth. However, in mid-May, Voyager 1's onboard component responsible for maintaining its high-gain antenna pointed at Earth, known as the attitude articulation and control system, or AACS, began beaming home incomprehensible jumbles of data instead of the regular bulletins about the spacecraft's health and status. From our perspective, it appeared that the spacecraft had suffered an electronic form of aphasia, a disorder that causes the loss of fluent speech.
“The data may appear to be randomly generated, or does not reflect any possible state the AACS could be in,” explained NASA in a statement from the time.
Even more perplexing for engineers, despite the spacecraft's strange status updates, Voyager 1 appeared to be in fine condition. The radio signal from the spacecraft remained strong and consistent, indicating that the antenna was still pointing at Earth — and not in the configuration the AACS claimed to NASA in the reports. Similarly, Voyager 1's science systems continued to gather and transmit data as usual, with no peculiarity influencing the AACS. Furthermore, whatever was wrong with the AACS did not trigger a fault prevention system designed to put the spaceship in safe mode when there is a problem.
Fortunately, NASA engineers identified the issue. They could also use the diagnosis to find a cure.
THE FIX – It was discovered that the AACS had been sending telemetry data via an onboard computer that had stopped working years before. The corrupted data was caused by the deceased computer. All NASA engineers had to do was instruct the AACS to utilise the appropriate computer to send its data home.
BUT THERE'S STILL A PROBLEM — The next step will be to determine what prompted the AACS to swap systems in the first place. According to NASA, the system most likely received an incorrect order from another onboard computer. While they claim it is not a serious concern for Voyager 1's well-being at the moment, the underlying culprit must be located and rectified to prevent future strangeness.
LIVES ON VOYAGER 1
No one could have imagined the discoveries made by Voyager 1 regarding our Solar System. Universal History Archive/Universal Images Group/Getty Images
Voyager 1 is currently more than 23.4 billion kilometres or 14.6 billion miles away from Earth (and gaining most of the time). On NASA's website, you can watch the distance develop and view the current positions of both Voyager spacecraft in space.
Voyager 1 has spent the last decade drifting in interstellar space, beyond the reach of our Sun's magnetic field. The field shielded the craft from cosmic rays and other interstellar radiation in the same way that Earth's magnetic field shields us from high-energy particles and radiation from the Sun. When one of those high-speed energetic particles strikes a computer chip, it can cause minor memory errors that mount up over time, and it's realistic to expect that to be a concern for Voyager 1's onboard computers as well.
“A mystery like this is sort of par for the course at this stage of the Voyager mission,” said Voyager 1 and 2 project manager Suzanne Dodd in a statement dated to May.
“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.”
We'll have to wait and see what new dangers await Voyager on its next journey — and what new discoveries await.
Reference(s): NASA
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