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For the first time in five months, NASA engineers have received detectable data from Voyager 1 after creating a creative solution to a communication problem on mankind’s most distant spacecraft in the cosmos.
Voyager 1 is currently about 15 billion miles (24 billion kilometers) away, and at 46 years old, the probe has shown many quirks and signs of aging over the years.
The most recent issue experienced by Voyager 1 first surfaced in November 2023, when the telemetry modulation unit of the flight data system began sending an insurmountable repeating pattern of code.
Voyager 1’s flight data system collects information from the spacecraft’s science instruments and bundles it with engineering data that shows its current health status. Mission control on Earth receives that data in binary code, or a series 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 its mission control team on Earth for the past few months, the signal contained no usable data.
The mission team received the first coherent data about the health and status of Voyager 1’s engineering systems on April 20. Although 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 in a statement Saturday. “We are back in communication with the spacecraft. And we look forward to getting scientific data back.”
The change came about as a result of a clever bit of trial and error and the revelation of a mystery that left the team on edge.
Troubleshooting from billions of miles away
After discovering the issue, the mission team attempted to send commands to restart the spacecraft’s computer system and learn more about the root cause of the problem.
The team sent Voyager 1 a command called “poke” on March 1 to make the flight data system run different software sequences in hopes of finding out what caused the glitch.
On March 3, the team noticed that activity from one part of the flight data system stood out from the rest of the garbled data. Although the signal was not in the format the Voyager crew is used to seeing when the flight data system is operating as expected, an engineer with NASA’s Deep Space Network was able to decode it.
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.
The decoded signal included a readout of the entire flight data system memory.
By investigating the readout, the team determined the cause of the issue: 3% of the flight data system memory is corrupted. One chip responsible for storing some of the system’s memory, including some of the computer’s software code, is not working properly. While the cause of the chip’s failure is unknown, it could have worn out or been hit by an energetic particle from space, the team said.
Because the code on the chip was lost, Voyager 1’s science and engineering data was unusable.
Since there was no way to repair the chip, the team opted to store the affected code from the chip elsewhere in the system’s memory. Although they were unable to find a location large enough to hold all of the code, they were able to split the code into parts and store it in different spots within the flight data system.
“For this plan to work, they also had to adjust those code segments to make sure, for example, that they all still function as a whole,” according to an update from NASA. “Any references to the location of that code in other parts of the (flight data system) memory would also need to be updated.”
After determining the code necessary to package Voyager 1’s engineering data, engineers sent a radio signal to the probe directing the code to a new location in the system’s memory on April 18.
Because of Voyager 1’s great distance from Earth, it takes about 22.5 hours for the probe’s radio signal to reach Earth, and another 22.5 hours for a response signal from the spacecraft to reach Earth.
On April 20, the Voyager 1 team received a response indicating that the clever code modification had worked, and that they could finally receive readable engineering data from the probe again.
Exploration of interstellar space
In the coming weeks, the team will continue to relocate other parts of the affected system software, including those responsible for returning the valuable science data being collected by Voyager 1.
Originally conceived five years ago, Voyager 1 and its twin, Voyager 2, launched in 1977 and are the longest operating spacecraft in history. Their extremely long life spans mean that both spacecraft have provided further insights into our solar system and beyond after reaching their initial targets of flybys of Jupiter, Saturn, Uranus and Neptune decades from now. shin.
The probes are currently venturing through uncharted cosmic territory along the way beyond the solar system. Both are in interstellar space and are the only spacecraft ever to operate beyond the heliosphere, the Sun’s bubble of magnetic fields and particles that extends far beyond Pluto’s orbit.
Voyager 2, which is operating normally, has traveled more than 12.6 billion miles (20.3 billion kilometers) from our planet.
Over time, both spacecraft have encountered unexpected issues and crashes, including a seven-month period in 2020 when Voyager 2 was unable to communicate with Earth. In August 2023, the mission team used a long-shot “smile” technique to re-establish communications with Voyager 2 after the spacecraft’s antenna command was inadvertently pointed in the wrong direction.
The team estimates that it is a few weeks away from receiving science data from Voyager 1 and they are looking forward to seeing what that data holds.
“We never know for sure what will happen with the Voyagers, but it always amazes me when they keep going,” Suzanne Dodd, Voyager Project Manager, said in a statement. “We’ve had a lot of anomalies, and they’re getting harder. But we have so far been lucky to recover from them. And the mission keeps going. And younger engineers are joining the Voyager team and adding their knowledge to keep the mission going.”
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