Space 4 November 2026 4 MIN READ
How Voyager 1 Was Repaired from Space
A memory chip died in a 46-year-old computer, 24 billion kilometres away. How engineers found the fault, cut the code into pieces and fixed it.
THE SHORT ANSWER
Voyager 1 stopped sending readable data in November 2023 because one memory chip in a 46-year-old computer failed. Engineers split the affected code into pieces and stored them elsewhere, then sent the patch across a 22.5-hour delay. By June 2024 all four remaining instruments were working again.
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A 1977 computer with a 2024 problem
Voyager 1 left Earth in 1977 and is now the most distant human-made object. Each Voyager has three programmable computers: one for commands, one for flight data and one for attitude control. NASA’s 1980 backgrounder says the command computer has two independent memories of 4,096 words each, and a pre-launch JPL description puts each word at 18 bits. The computers were built by General Electric to JPL’s specifications and execute only about 8,000 instructions per second.
We could not find a primary NASA source for the memory size of the flight data computer, the one that failed. The total often quoted online is unverified.
November 2023: the data turns to gibberish
On 14 November 2023, Voyager 1 stopped sending readable science and engineering data, although it still received commands and otherwise seemed fine. In December 2023 NASA reported that the telemetry unit was sending a repeating pattern of ones and zeros, and traced the problem to the flight data computer.
Every step was slow. A command and its answer took 45 hours. The team worked from original design documents that are decades old.
The diagnosis
On 1 March 2024 engineers sent a “poke” command that gently prompted the computer to try different software sequences, in case it could route around a corrupted section. The response, received on 3 March, turned out to be a readout of the computer’s entire memory, which a Deep Space Network engineer decoded and confirmed on 10 March.
Comparing it with the expected contents showed that about 3% of the memory was corrupted, traced to a single chip that had stopped working. NASA says it could not determine whether a hit by a cosmic particle or simple wear after 46 years killed the chip.
The fix
The chip could not be repaired, and no single memory location was big enough to hold the affected code. So the engineers split the code into sections, stored them in different places in the computer’s memory, and updated the references between them.
The first relocated section, which packages engineering data, was sent on 18 April 2024. The team heard back on 20 April and received health and status data for the first time in five months. The one-way travel time was about 22.5 hours, at a distance of more than 15 billion miles (24 billion kilometres). A second step on 19 May restored science data, and by 13 June 2024 all four remaining science instruments were returning usable data.
Keeping a veteran running
Since then, the fixes have been about power. Each Voyager loses about 4 watts a year as its plutonium decays. In March 2025, engineers revived thrusters that had been considered dead since 2004, after suspecting a mis-set switch in a heater circuit. In April 2026, the Low-Energy Charged Particles instrument was switched off to save power, and in early September 2026 engineers swapped three devices for lower-power alternatives. Without that swap, another instrument would have had to be turned off as early as the summer of 2027.
In October 2026 the spacecraft briefly fell silent after a thruster group went offline and automatic fault protection switched on the backups; contact was back by 20 October.
One light-day
On 18 November 2026, Voyager 1 is due to reach a distance of one light-day from Earth: 16,094,799,096 miles by NASA’s count. A radio signal then takes 24 hours one way, 48 hours for a round trip.
Why it matters
This was a software patch for a 46-year-old computer, cut into pieces, scattered across free memory and sent across a 22.5-hour delay. And it worked.
Our take: a repair made across 24 billion kilometres. The lesson is not nostalgia. It is that careful documentation, patience and a design with room to move can outlast the people who built it.
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Sources
- The Voyager Spacecraft (NASA/JPL Voyager backgrounder, release 80-160) · NASA / JPL via NASA Technical Reports Server · Accessed
- Voyager Mission Description (E. C. Kohlhase and P. A. Penzo) · NASA Planetary Data System (JPL preprint) · Accessed
- Frequently Asked Questions · NASA Science · Accessed
- Engineers Working to Resolve Issue With Voyager 1 Computer · NASA Science (Voyager blog; repost of Dec. 12, 2023 post) · Accessed
- NASA’s Voyager 1 Resumes Sending Engineering Updates to Earth · NASA Jet Propulsion Laboratory · Accessed
- NASA Engineers Make Progress Toward Understanding Voyager 1 Issue · NASA Science (Voyager blog; repost of Mar. 13, 2024 post) · Accessed
- Engineers Pinpoint Cause of Voyager 1 Issue, Are Working on Solution · NASA Science (Voyager blog) · Accessed
- Voyager 1 Returning Science Data From All Four Instruments · NASA Science (Voyager blog) · Accessed
- NASA’s Voyager 1 Revives Backup Thrusters Before Command Pause · NASA Science / JPL · Accessed
- NASA’s Voyager 1 Conserves Power, Resolves Brief Communications Pause · NASA Jet Propulsion Laboratory · Accessed
- Voyager 1: What Is a Light-Day · NASA Science · Accessed
- Where Are Voyager 1 and 2 Now? · NASA Science · Accessed
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