Voyager 1 Sends Nonsense Data from Deep Space

For months, the most distant human-made object in existence stopped making sense. Voyager 1, currently sailing through interstellar space over 15 billion miles from Earth, began sending back a repeating stream of indecipherable binary code in late 2023. What followed was a high-stakes troubleshooting mission by NASA engineers to save one of humanity’s greatest scientific achievements using technology from the 1970s.

The Day Voyager Stopped Speaking

In November 2023, the flight controllers at NASA’s Jet Propulsion Laboratory (JPL) in Southern California noticed a critical error. While the spacecraft was still receiving commands and operating normally, the data returning to Earth was useless. The telemetry modulation unit, which is responsible for packaging engineering and science data for transmission, began streaming a repeating pattern of ones and zeros.

The issue was traced to the Flight Data System (FDS). This is one of the probe’s three onboard computers. The FDS is responsible for collecting data from the science instruments and bundling it with engineering data about the spacecraft’s health. When the FDS failed, Voyager 1 effectively became a mute wanderer. It was alive, but it could not tell NASA what it was seeing or how it was feeling.

Diagnosing a Glitch 15 Billion Miles Away

Fixing a computer glitch on Earth is usually a matter of rebooting or replacing a part. Fixing a glitch on Voyager 1 involves a communication lag of roughly 22.5 hours each way. Every time engineers at JPL sent a command, they had to wait 45 hours to see if it worked.

After months of analyzing the gibberish data, the team attempted a “poke” command on March 1, 2024. This command was designed to prompt the FDS to try different sequences in its software package in case the corruption was located in a specific area.

The gamble paid off. On March 3, the team received a signal that differed from the repeating loop. While still not standard data, an engineer with the Deep Space Network was able to decode it. The decoding revealed a complete memory dump of the FDS. By comparing this to the code Voyager 1 had before the glitch, the team identified the specific culprit: a single chip responsible for storing a portion of the FDS memory had failed.

The Likely Cause

Engineers cannot physically inspect the probe, but they have two leading theories for the hardware failure:

Cosmic Rays: A high-energy particle from deep space may have struck the chip, corrupting its ability to store data.
Hardware Fatigue: The spacecraft launched in 1977. After 46 years of operation in the harsh environment of space, the silicon simply wore out.

The "Impossible" Software Patch

Because the chip was physically broken, it could not be fixed. The only solution was to move the affected code to a different location in the FDS memory. However, there was a significant catch. No single location in the remaining memory was large enough to hold the section of code that needed moving.

The team at JPL had to devise a complex plan to slice the code into smaller chunks. These chunks were then stored in various free spaces within the FDS memory. This was not a simple “copy and paste” job. The code had to be rewritten so that the different chunks could still reference each other and function as a cohesive whole. Additionally, other parts of the FDS memory had to be updated to recognize where the code had moved.

The Restoration Timeline

April 18, 2024: NASA sent the code to move the specific section responsible for engineering data.
April 20, 2024: After a tense 45-hour wait, the team received clear, readable data for the first time in five months. They could finally confirm the health and status of the spacecraft.
May 2024: The team sent subsequent commands to relocate the remaining code responsible for returning science data.
Current Status: As of late May 2024, Voyager 1 resumed normal science operations. Instruments like the plasma wave subsystem and magnetometer began returning unique data about interstellar space once again.

Understanding the Voyager Technology

The feat of fixing Voyager 1 is even more impressive when considering the hardware involved. The computers aboard Voyager have less than 70 kilobytes of memory total. For comparison, a standard modern smartphone has hundreds of thousands of times more memory than the Voyager spacecraft.

The FDS itself was the first computer on a spacecraft to use volatile memory. The engineers essentially performed delicate software surgery on a machine built when disco was popular, using documentation that was written on paper almost 50 years ago.

Frequently Asked Questions

How long does it take for a signal to reach Voyager 1? As of 2024, it takes approximately 22.5 hours for a radio signal traveling at the speed of light to reach Voyager 1. A round-trip communication takes roughly 45 hours.

Is Voyager 1 still in the Solar System? Voyager 1 crossed the heliopause in August 2012, entering interstellar space. This is the region between stars, beyond the bubble of hot plasma generated by our Sun. It is the first human-made object to do so.

How much longer will Voyager 1 last? The spacecraft is powered by a radioisotope thermoelectric generator (RTG), which converts heat from decaying plutonium into electricity. The power output decreases by about 4 watts per year. NASA expects to have to turn off the final science instruments around 2025 or shortly thereafter, though the probe may continue to send weak engineering signals until the 2030s.

What happens after Voyager 1 runs out of power? Once the power is depleted, Voyager 1 will drift silently through the Milky Way. It carries the Golden Record, a gold-plated copper disk containing sounds and images selected to portray the diversity of life and culture on Earth, intended for any extraterrestrial intelligence that might find it.