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NASA engineers have received decipherable data from Voyager 1 for the first time in five months after coming up with a creative solution to solve humanity’s communications problem on the most distant spacecraft in the universe.
Voyager 1 is now about 15 billion miles (24 billion kilometers) away and the 46-year-old probe has shown numerous quirks and signs of aging in recent years.
The latest problem experienced by Voyager 1 was first revealed in November 2023, when the flight data system’s telemetry modulation unit began sending an undecipherable 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 its current health status. Mission control on Earth receives this data as binary code or a string of ones and zeros.
But since November, Voyager 1’s flight data system has been stuck in a loop. Although the probe continued to send a steady radio signal to mission control on Earth for the past several months, the signal was not carrying any usable data.
The mission team received the first consistent data on the health and status of Voyager 1’s engineering systems on April 20. While the team is still reviewing the information, everything they’ve seen so far indicates that Voyager 1 is healthy and functioning properly.
“Today was a great day for Voyager 1,” Linda Spilker, Voyager project scientist at JPL, said Saturday. “We are in communication with the spacecraft again. “And we look forward to getting the science data back.”
This breakthrough came as a result of clever trial and error and solving the mystery that led the team to a single chip.
Troubleshooting from billions of kilometers away
After discovering the problem, the mission team attempted to send commands to reboot the spacecraft’s 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 get the flight data system to run different sequences of software in hopes of finding the cause of the glitch.
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 that the Voyager crew was accustomed to seeing 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 radio antenna system on Earth that helps the agency communicate with the Voyager probes and other spacecraft exploring our solar system.
The decoded signal involved reading the memory of the entire flight data system.
By examining the reading, the team determined the cause of the problem: 3% of the flight data system memory is corrupt. A single chip responsible for storing some of the computer’s system memory, including some of its software code, is not working properly. The team said that although the cause of the chip’s failure is unknown, it may have worn out or been hit by an energetic particle from space.
The loss of the code on the chip rendered Voyager 1’s science and engineering data unusable.
Since there was no way to repair the chip, the team opted to store the affected code on the chip elsewhere in the system’s memory. Although they could not determine a place large enough to hold the entire code, they were able to divide the code into sections and store them at different points within the flight data system.
“For this plan to work, they needed to adjust these sections of code, for example, to make sure they all still worked as a whole,” according to an update from NASA. “Any reference to the location of this code in other parts of the (flight data system) memory also had to be updated.”
After engineers determined the code needed to package Voyager 1’s engineering data, they sent a radio signal to the probe on April 18 that directed the code to a new location in the system’s memory.
Given that Voyager 1 is so far from Earth, it takes approximately 22.5 hours for the radio signal to reach the probe, and the response signal from the spacecraft also takes 22.5 hours to reach Earth.
On April 20, the team received the response from Voyager 1 stating that the clever code change had worked and that they were finally able to receive readable engineering data from the probe once again.
Exploring interstellar space
Over the coming weeks, the team will continue to relocate other affected parts of the system software, including those responsible for sending back the valuable science data Voyager 1 collected.
Originally designed to last five years, Voyager 1 and its twin, Voyager 2, were launched in 1977 and are the 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.
Probes are currently passing through unexplored cosmic regions throughout the outer regions of the solar system. 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.
Operating normally, Voyager 2 traveled more than 12.6 billion miles (20.3 billion kilometers) from our planet.
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, the mission team used the long-shot “shout” technique to restore communications with Voyager 2 after a command accidentally directed the spacecraft’s antenna in the wrong direction.
The team estimates that science data from Voyager 1 is several weeks away, and they can’t wait to see what that data contains.
“We never know for sure what will happen to the Voyagers, but it continually amazes me that they keep going,” Voyager Project Manager Suzanne Dodd said in a statement. “We have had many anomalies and they are becoming increasingly difficult. But we’ve been lucky to avoid them so far. And the mission continues. And young engineers come to the Voyager team and contribute their knowledge to keep the mission going.”
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