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Engineers sent a “nudge” to the Voyager 1 probe and received a potentially encouraging response as they hoped to solve a five-month-old communications problem on the aging spacecraft.
Launched in 1977, Voyager 1 and its twin, Voyager 2, venture into uncharted cosmic regions along the outer reaches of the solar system.
While Voyager 1 continued to send a steady radio signal to mission control staff on Earth, that signal had not carried any usable data since November, indicating a problem with one of the spacecraft’s three onboard computers.
A new signal recently received from the spacecraft indicates that the NASA mission team may be making progress in its quest to understand what Voyager 1 is experiencing. Voyager 1 is currently the furthest spacecraft from Earth, at approximately 15 billion miles (24 billion kilometers).
Meanwhile, Voyager 2 has moved more than 12.6 billion miles (20.3 billion kilometers) from our planet. Both are in interstellar space and are the only spacecraft operating beyond the heliosphere, the sun’s bubble of magnetic fields and particles that extends far beyond Pluto’s orbit.
Originally designed to last five years, the Voyager probes are the two longest-operating spacecraft in history. Their exceptionally long lifetimes mean that both spacecraft are providing additional information about our solar system and beyond after achieving their preliminary goal of flying past Jupiter, Saturn, Uranus and Neptune decades ago.
But both probes encountered difficulties as they aged.
Cosmic communications disruption
The mission team first became aware of the communications problem with Voyager 1 on November 14, 2023, when the flight data system’s telemetry modulation unit began sending a repeating code pattern.
Voyager 1’s flight data system collects information from the spacecraft’s science instruments and combines it with engineering data that reflects Voyager 1’s current health status. Mission control on Earth receives this data in binary code or a string of ones and zeros.
But since November, Voyager 1’s flight data system has been stuck in a loop.
The spacecraft was still able to receive and execute commands transmitted from the mission team, but a problem with the telecommunications unit meant that Voyager 1 did not transmit any science or engineering data to Earth.
Since the discovery of the problem, the mission team has attempted to send commands to reboot the computer system and learn more about the underlying cause of the problem.
The team sent a command called a “nudge” to Voyager 1 on March 1 to make the flight data system run different sets of software in case some kind of glitch caused the problem.
On March 3, the team noticed that activity in one part of the flight data system stood out from the rest of the corrupted data. Although the signal was not in the format the Voyager team was accustomed to when the flight data system worked as expected, an engineer from NASA’s Deep Space Network was able to decode the signal.
The Deep Space Network is a system of radio antennas on Earth that helps the agency communicate with the Voyager probes and other spacecraft exploring our solar system.
According to an update shared by NASA, the decoded signal involved reading the memory of the entire flight data system.
“(The flight data system) contains memory, code, or instructions for what to do, as well as variables or values that can change depending on the commands used in the code or the state of the spacecraft,” according to a NASA blog post. “It also includes science or engineering data for the downlink. The team will compare this reading with information from before the problem occurred and look for inconsistencies in the code and variables to potentially find the source of the ongoing problem.”
How do the Voyager probes keep going?
Voyager 1 is so far away that commands sent from Earth take 22.5 hours to reach the spacecraft. Additionally, the team must wait 45 hours to receive a response. Currently, the team is analyzing Voyager 1’s memory read after starting the decoding process on March 7 and finding the read three days later.
“It will take time to use this information to design a potential solution and try to put it into action,” according to the space agency.
The last time Voyager 1 experienced a similar but not identical problem with its flight data system was in 1981, and the current problem does not appear to be linked to other glitches the spacecraft has experienced in recent years.
Over time, both spacecraft encountered unexpected problems and disruptions; This includes a seven-month period in 2020 when Voyager 2 was unable to communicate with Earth. In August 2023, after a command accidentally pointed the spacecraft’s antenna in the wrong direction, the mission team used the long-shot “shout” technique to restore communication with Voyager 2.
As the aging twin Voyager probes continue to explore the universe, the team is slowly shutting down the instruments on these “senior citizens” to preserve power and expand their mission, Voyager’s project manager Suzanne Dodd previously told CNN.
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