NASA/JPL-Caltech
NASA’s Voyager 1 is shown in an artist’s illustration as the spacecraft travels through interstellar space, or the space between stars.
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The Voyager 1 spacecraft is sending back a steady stream of scientific data from uncharted territory for the first time since a computer glitch knocked out NASA’s historic mission seven months ago.
The currently farthest spacecraft from Earth, Voyager 1, stopped communicating coherently with mission control in November 2023. The probe appeared to be in a “Groundhog Day” scenario, with its flight data system’s telemetry modulation unit sending back an indecipherable repeating code pattern from a billion miles away.
A creative repair by the Voyager mission team restored communications with the spacecraft, and technical data began being transmitted back to mission control in April, informing the team of the health and operational status of the spacecraft.
However, data from Voyager 1’s four science instruments, which study plasma waves, magnetic fields and particles, have remained elusive. This information is important to show scientists how particles and magnetic fields change as the probe travels further.
On May 19, the Voyager team sent the spacecraft a command to begin returning science data. Two of the instruments responded, but it took a long time to get data from the other two and the instruments required recalibration. Now, all four instruments are transmitting back usable science data, according to an update shared by NASA on June 13.
Voyager 1’s flight data system is responsible for collecting information from the spacecraft’s science instruments and combining it with technical data that reflect the health of the probe. Mission Control on Earth, located at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, receives this data in binary code, or a series of ones and zeros.
It took Voyager specialists some time and some thought to decode the spacecraft’s garbled code. But once they did, they determined the cause of the problem: 3% of the flight data system’s memory was corrupted.
A single chip responsible for storing part of the system’s memory, including some of the computer’s software code, malfunctioned, and the loss of the code on the chip rendered Voyager 1’s science and engineering data unusable.
With no way to repair the chip, the team stored the affected code from the chip elsewhere in the system’s memory. They could not determine a location large enough to hold the entire code, so they divided it into sections and stored them in different locations in the flight data system.
There are still minor fixes needed to handle the effects of the initial problem.
“Among other tasks, engineers will resynchronize the timing software in the spacecraft’s three on-board computers to execute commands at the correct time,” the agency said. “The team will also maintain the digital tape recorder that records some of the data for the plasma wave instrument that is sent to Earth twice a year.
(Most Voyager science data is sent directly to Earth and not recorded.)
Meanwhile, Voyager 1 returns to what it does best: Sharing insights from uncharted space territory.
The probe is currently about 24 billion kilometers from Earth, while its sister vehicle Voyager 2 has traveled more than 20 billion kilometers from Earth. The twin probes took off within weeks of each other in 1977, and after initially flying past Jupiter, Saturn, Uranus and Neptune, their missions have been extended to 46 years and counting.
Both are located in interstellar space and are the only spacecraft operating outside the heliosphere—the sun’s bubble of magnetic fields and particles that extends far beyond Pluto’s orbit.
As humanity’s only extension outside the protective bubble of the heliosphere, the two probes are alone on their space journeys as they travel in different directions.
Imagine the planets of Earth’s solar system as existing in one plane. Voyager 1’s trajectory took it up and out of the plane after passing Saturn, while Voyager 2 passed over the top of Neptune and moved down and out of the plane, Suzanne Dodd, Voyager’s project manager at JPL, previously told CNN.
The information collected by these long-lived probes, the only two probes to directly sample interstellar space with their instruments, is helping scientists learn about the cometary shape of the heliosphere and how it shields Earth from charged particles and radiation in interstellar space.
Over time, both probes encountered unexpected problems and outages, including a seven-month period in 2020 when Voyager 2 was unable to communicate with Earth. In August 2023, the mission team used the long “scream” technique to restore communications with Voyager 2 after the command inadvertently pointed the spacecraft’s antenna in the wrong direction.
“We never know for sure what will happen with the Voyagers, but it continues to amaze me that they keep going,” Dodd said in April.