Voyager 1 Restoration: NASA Resumes Data Collection from Interstellar Space

For nearly half a century, Voyager 1 has served as humanity’s most distant outpost. When the probe stopped sending readable data in late 2023, fears mounted that the mission was finally over. However, in a remarkable display of remote engineering, NASA’s Jet Propulsion Laboratory (JPL) successfully implemented a complex software fix. The probe is once again returning vital scientific data from the space between the stars.

The Crisis: When Voyager Went Silent

The trouble began in November 2023. While Voyager 1 continued to broadcast a steady radio signal back to Earth, the information within that signal became unreadable. Instead of the binary code (0s and 1s) that represents scientific measurements and engineering health, the telemetry stream turned into a repeating pattern of gibberish.

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 packaging data from the science instruments and engineering sensors before sending it to the Telemetry Modulation Unit (TMU) for transmission to Earth. When the FDS failed, the communication line remained open, but the message was blank.

Diagnosing the problem was difficult due to the extreme distance. Voyager 1 is over 15 billion miles away from Earth. A radio command takes about 22.5 hours to reach the spacecraft, and the response takes another 22.5 hours to return. This means the engineering team had to wait nearly two days to see the result of any single test.

Finding the Fault

In March 2024, the team sent a “poke” command to the spacecraft. This command was designed to prompt the FDS to try different software sequences in hopes of bypassing the corrupted section. One of the responses contained a memory dump of the FDS computer.

By analyzing this readout, engineers pinpointed the exact cause of the silence. A single memory chip within the FDS had failed. This chip held a specific portion of the software code responsible for bundling the spacecraft’s data. Because that chip was physically broken, the computer got stuck in a loop and could not process information correctly.

Since there is no way to physically repair a computer chip located 15 billion miles away, the team had to resort to a software workaround.

The Solution: A High-Stakes Code Transplant

The solution involved moving the affected code to a different location in the FDS memory. However, this was not a simple copy-and-paste operation. The 1970s-era computer has extremely limited memory capacity. There was no single block of free memory large enough to hold the entire section of code they needed to move.

The engineers devised a plan to slice the code into sections. They stored these chunks in various free spots throughout the memory bank. To make this work, they also had to update the code to ensure that every reference to the old memory location was redirected to the new locations.

This required modifying the assembly code instructions manually. If a single reference was missed, the computer could crash entirely, potentially ending the mission.

Timeline of the Restoration

• November 2023: Voyager 1 begins sending unreadable data.
• March 1, 2024: NASA sends a “poke” command to prompt a memory readout.
• April 18, 2024: The team sends the new code to the spacecraft.
• April 20, 2024: JPL receives confirmation that the fix worked. Voyager 1 begins returning readable engineering data regarding its health and status.
• May/June 2024: The team sends commands to restart the science instruments.
• Present: All four operational science instruments are returning usable data.

Current Status of Scientific Instruments

Following the restoration of engineering data, the team focused on bringing the scientific instruments back online. As of mid-2024, Voyager 1 is fully operational. The probe is actively collecting information using its four remaining instruments:

1. Plasma Wave Subsystem: This instrument measures the density of the plasma (ionized gas) in the interstellar medium. It helps scientists determine the density of the environment outside our solar bubble.
2. Magnetometer: This tool measures the magnetic field. It is crucial for understanding how the sun’s magnetic influence interacts with the magnetic field of the galaxy.
3. Cosmic Ray Subsystem: This detects high-energy particles. It helps researchers understand the radiation environment in interstellar space.
4. Low Energy Charged Particle Instrument: This measures the intensity of charged particles, such as electrons and protons.

The data provided by these instruments is unique. No other active spacecraft is in the interstellar medium (though Voyager 2 is close behind). This makes every bit of data retrieved from Voyager 1 irreplaceable.

The Challenges of 1970s Hardware

The success of this repair highlights the incredible durability of the Voyager hardware and the ingenuity of the current team. The computers on Voyager 1 have less than 70 kilobytes of memory. For comparison, a standard smartphone photo uses vastly more data than the Voyager’s entire memory bank.

The engineers often have to consult paper documents written in the 1970s to understand the original design logic. The software is written in archaic languages that are rarely used today. This restoration ensures that the probe can continue to function until its power supply eventually dwindles.

What Comes Next for Voyager 1?

With the FDS fixed, the primary constraint on Voyager 1 is now power. The spacecraft runs on a radioisotope thermoelectric generator (RTG), which converts heat from decaying plutonium into electricity. The generator produces about 4 watts less power each year.

To keep the probe running, engineers have already turned off non-essential systems, including heaters and cameras. The team estimates that they will have to start turning off science instruments one by one around 2025 or 2026 to conserve power. However, thanks to the FDS repair, the probe is expected to continue sending at least some data until roughly 2030.

Frequently Asked Questions

How long does it take to send a message to Voyager 1? As of the current distance, it takes approximately 22.5 hours for a radio signal to travel from Earth to Voyager 1. A round-trip communication takes roughly 45 hours.

Why can’t NASA replace the broken chip? Voyager 1 is over 15 billion miles away from Earth. It is physically impossible to send a repair crew or robot to the spacecraft. All repairs must be done via software commands sent from Earth.

Is Voyager 2 also having problems? Voyager 2 is currently operating normally. It is slightly closer to Earth than Voyager 1 and continues to transmit data from the interstellar medium. The patch used on Voyager 1 may be used on Voyager 2 in the future as a preventative measure.

When will Voyager 1 stop working permanently? NASA expects the power supply to drop below the level needed to operate a single instrument around 2030. At that point, the probe will continue to fly through the galaxy as a silent ambassador, but it will no longer communicate with Earth.