NASA Restores Voyager 1 Data Transmission from Interstellar Space
After five months of suspense and silence, NASA has successfully reestablished meaningful communication with Voyager 1. The spacecraft, currently the farthest human-made object in existence, stopped sending readable data in late 2023. Through a clever software fix executed over 15 billion miles away, engineers at the Jet Propulsion Laboratory (JPL) have saved the historic mission.
The Glitch That Silenced a Probe
The trouble began on November 14, 2023. While Voyager 1 continued to phone home, the signal it returned contained no usable information. Instead of the usual stream of binary code containing science and engineering updates, the spacecraft began transmitting a repeating pattern of ones and zeros. It was essentially speaking gibberish.
The mission team at NASA’s JPL in Southern California traced the issue to the Flight Data System (FDS). This is one of the probe’s three onboard computers. The FDS is responsible for packaging data from the science instruments and bundling it with engineering data about the health of the spacecraft before sending it back to Earth.
For months, the team attempted to restart the system and troubleshoot the error. The process was agonizingly slow. Because Voyager 1 is more than 15 billion miles (24 billion kilometers) from Earth, a radio signal takes 22.5 hours to reach the spacecraft. A response takes another 22.5 hours to return. This means the team had to wait nearly two days to see if any specific command worked.
Identifying the Hardware Failure
In early March 2024, the engineering team attempted a “poke” command. This command was designed to prompt the FDS to try different sequences in its software package in case a corrupted section was causing the loop.
The gamble paid off. On March 3, the team received a signal that looked different from the repeating loop they had seen since November. While it was not yet standard data, an engineer at the Deep Space Network was able to decode it. The signal contained a complete memory dump of the FDS computer.
By comparing this new memory readout to one from before the glitch, the team pinpointed the exact problem. A single chip responsible for storing a portion of the FDS memory had failed. This chip accounted for about 3% of the computer’s system memory. Unfortunately, that specific 3% contained the software code required to package and transmit data.
The "Impossible" Fix from 15 Billion Miles Away
Since the chip is hardware, it could not be repaired from Earth. The only option was a software workaround. The engineers needed to move the affected code to a different location in the FDS memory.
However, there was a significant hurdle. No single location in the remaining memory was large enough to hold the entire section of code that needed to be moved. The memory on Voyager 1 is incredibly limited by modern standards. The computers on board have less than 70 kilobytes of total memory.
The team devised a complex solution:
- Code Slicing: They broke the code into smaller chunks.
- Distribution: These chunks were scattered across different available spots in the FDS memory.
- Relinking: The team had to rewrite the code to ensure all the chunks could still function together as a cohesive unit. This involved updating references and “pointers” so the system knew exactly where to find the next instruction.
Restoration of Science Data
On April 18, 2024, the team sent the code to move the first section of the data. This section was responsible for packaging the spacecraft’s engineering data. After a tense 45-hour wait, the team received a reply on April 20. The fix worked. For the first time in five months, Voyager 1 sent back readable data regarding its health and status.
Following this initial success, the team began relocating the remaining portions of the code responsible for the science instruments. By late May 2024, two of the four science instruments resumed sending data. By mid-June, NASA confirmed that all four remaining operational instruments were returning usable science data.
These instruments include:
- The Plasma Wave Subsystem
- The Magnetometer
- The Cosmic Ray Subsystem
- The Low Energy Charged Particle instrument
The Significance of Voyager 1
Voyager 1 was launched in 1977, originally designed for a five-year mission to study Jupiter and Saturn. It has now been operating for over 46 years. In August 2012, it became the first human-made object to cross the heliopause and enter interstellar space.
The region Voyager 1 explores is outside the heliosphere, the protective bubble of particles and magnetic fields created by our Sun. The data it provides gives scientists their only direct look at the interstellar medium. Without Voyager 1, we would have to rely entirely on remote observations from telescopes.
The spacecraft is powered by a radioisotope thermoelectric generator (RTG), which converts heat from decaying plutonium into electricity. The power output decreases by about four watts per year. To keep the probe alive, mission controllers have gradually turned off non-essential systems, including heaters and cameras, to conserve energy for the science instruments and the transmitter.
Comparison with Voyager 2
Voyager 1 has a twin, Voyager 2, which also launched in 1977. Voyager 2 entered interstellar space in 2018 and is currently about 12.6 billion miles from Earth. While Voyager 2 is functioning normally, the distance between the two probes means they are sampling different parts of the interstellar medium. Keeping both operational provides a stereo view of the environment surrounding our solar system.
This successful repair extends the life of the Voyager 1 mission, likely allowing it to continue gathering data until the power supply becomes too weak to support the instruments, which is expected to happen sometime around 2030.
Frequently Asked Questions
How long does it take to send a command to 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.
What caused the communication breakdown? The breakdown was caused by a single failed memory chip in the Flight Data System (FDS). This chip stored code necessary for packaging science and engineering data for transmission.
Is Voyager 1 still sending photos? No. The cameras on Voyager 1 were turned off in 1990 to save power and memory after it took the famous “Pale Blue Dot” image. The current mission focuses on measuring plasma waves, magnetic fields, and cosmic rays.
How much memory does Voyager 1 have? The computers aboard Voyager 1 have roughly 68 to 70 kilobytes of memory. For comparison, a standard smartphone today has hundreds of thousands of times more memory than the Voyager spacecraft.
What happens when Voyager 1 runs out of power? Once the power output drops below what is needed to run the transmitter and instruments, Voyager 1 will fall silent. It will continue to drift through the Milky Way galaxy as a silent ambassador, carrying the Golden Record, effectively forever.