For the first time since November 2023, NASA’s Voyager 1 spacecraft has started transmitting useful data back to Earth about the status and functionality of its onboard systems.
The mission team is now preparing for the spacecraft to resume sending back scientific data. Voyager 1, along with its sibling Voyager 2, are the only spacecraft to venture into interstellar space.
Malfunction in Voyager’s computers
Voyager 1 had ceased transmitting intelligible science and engineering data on November 14, 2023. Although the spacecraft appeared to be receiving instructions and operating as expected, the data it sent back was unreadable.
In March, the engineering team at NASA’s Jet Propulsion Laboratory (JPL) in Southern California diagnosed the problem as being related to a malfunction in one of the spacecraft’s three onboard computers, specifically the flight data subsystem (FDS). This system is responsible for organizing the science and engineering data before it is sent to Earth.
Resurgence of Voyager data
The resurgence of data transmission in April 2024 was met with celebrations by the Voyager team at JPL. The malfunction was traced back to a single memory chip within the FDS that had failed.
This chip was crucial as it held part of the FDS’s memory, including segments of its software code, essential for processing the data sent to Earth.
With the chip non-functional and irreplaceable, the team attempted to reassign the code to different parts of the FDS memory. However, no single section of the memory was sufficiently large to accommodate the entire code.
Process of retrieving the Voyager data
The solution involved fragmenting the code into smaller segments and reallocating these across several memory locations. This intricate process required adjustments to ensure the fragmented code could operate seamlessly as a whole. This also involved updating references to the code’s location in the FDS memory.
The focus initially was on the segment of the code responsible for collating the spacecraft’s engineering data. This was successfully relocated within the FDS memory on April 18. Given Voyager 1’s immense distance – over 15 billion miles (24 billion kilometers) from Earth – it takes about 22 ½ hours for a signal to travel from Earth to the spacecraft and another 22 ½ hours for the response to return.
Enduring missions
When communications were reestablished on April 20, the team confirmed that the adjustments were successful, marking the first time in five months that they could verify the spacecraft’s operational health and status.
In the upcoming weeks, the Voyager team plans to reposition and modify the remaining sections of the FDS software, which are crucial for resuming the transmission of scientific data.
Meanwhile, Voyager 2 remains fully functional. Launched more than 46 years ago, the Voyager spacecraft – both Voyager 1 and Voyager 2 – are the most enduring and farthest-traveling spacecraft ever launched. Prior to entering interstellar space, each spacecraft conducted flybys of Jupiter and Saturn, with Voyager 2 also visiting Uranus and Neptune.
More about the Voyager mission
The NASA Voyager mission consists of two spacecraft, Voyager 1 and Voyager 2, which were launched in 1977 to explore the outer solar system and beyond. The primary goal of the mission was to take advantage of a rare planetary alignment that allowed for a grand tour of the outer planets – Jupiter, Saturn, Uranus, and Neptune.
This alignment occurs only once every 176 years, and the mission’s timing capitalized on this to extend our knowledge of these distant worlds.
Voyager 1
Voyager 1’s trajectory took it past Jupiter in March 1979 and Saturn in November 1980, providing detailed images and data on the planets and their moons. After its encounter with Saturn, Voyager 1’s path was adjusted so it would pass close to Saturn’s moon Titan and then head out of the solar system.
Voyager 2
Voyager 2, on a longer trajectory, passed Jupiter in July 1979, Saturn in August 1981, Uranus in January 1986, and Neptune in August 1989. Each flyby yielded significant scientific discoveries, including the first detailed images of these planets’ atmospheres, magnetic fields, rings, and numerous moons.
Interstellar space
After completing their primary missions, both Voyagers continued into the heliosheath – the outermost layer of the heliosphere where the solar wind is slowed by the pressure of interstellar gas. Voyager 1 entered interstellar space in August 2012, making it the first human-made object to do so. Voyager 2 followed into interstellar space in November 2018.
Ongoing communication
Despite their vast distance from Earth, the Voyagers continue to communicate with the NASA Deep Space Network to send back scientific data.
This enduring mission has expanded our understanding of the heliosphere and provides unique insights into the nature of the interstellar space beyond our solar system.
The spacecraft carry a golden record containing sounds and images selected to portray the diversity of life and culture on Earth, intended as a message for any intelligent extraterrestrial life that might find them.
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