NASA’s Voyager 1 and Voyager 2 spacecraft continue their journey through interstellar space powered by aging hardware, leaving a shrinking roster of engineers to maintain code written nearly fifty years ago, according to recent mission updates from the agency.
The Hardware and Code Keeping Voyager Alive
Launched in 1977, the twin Voyager spacecraft operate using onboard computers that run assembly language written for custom General Electric processors, according to technical reports published by TechRadar. Each spacecraft carries three separate computer systems with a total memory capacity ranging between 64 and 70 kilobytes across all systems—giving the probes less storage than a single small image file on a modern smartphone. NASA’s Suzy Dodd has compared operating Voyager to flying an Apple II computer, highlighting how primitive the computing resources have become by modern standards.
Popular accounts frequently suggest the spacecraft run on Fortran, but that description blurs two different functions. The low-level flight work depends on assembly language programming tailored to specialized hardware designed in the early 1970s, while Fortran has historically been associated with ground systems and older mission tooling rather than onboard flight software. When NASA searched for a replacement engineer in 2015, the job posting required both assembly language skills and a deep understanding of the unique hardware architecture.
Shrinking Institutional Memory and Aging Engineering Teams
Decades of continuous operations have created knowledge gaps that present greater challenges than the programming language itself. Around the start of the interstellar mission following Voyager 2’s flyby of Neptune in August 1989, the flight software was updated to increase spacecraft autonomy. That version, augmented by command sequences uploaded by the mission team every few months, forms the basis of the software running on both probes today.
However, the engineering team has shrunk and aged across decades, and much of the original paper documentation has been lost or fragmented. Larry Zottarelli was the last original Voyager engineer still working on the project when he retired in 2016 at the age of 80. All other original engineers are deceased or over 90 years old, including Dr. Gary Flandro, an aerospace/trajectory engineer now living in retirement. Suzy Dodd told Live Science that the people who built the spacecraft are no longer alive, leaving a small team to maintain code that no one fully understands.
Current Operations in Interstellar Space
Operating the probes requires managing vast communication delays. A signal from Voyager now takes more than 23 hours to reach Earth, and by the time NASA receives a status check, the spacecraft is already 1.5 million kilometers further into interstellar space. While the mission continues, institutional memory is fading faster than the plutonium power sources keeping the probes active. When the final engineers familiar with the assembly code retire or pass away, NASA will rely entirely on paper documentation and a diminishing signal to communicate with spacecraft beyond the solar system.
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