For the first time since November, NASA’s Voyager 1 spacecraft is providing usable data on the status of its onboard engineering systems.
The next step, NASA reported, is to allow the spacecraft to begin sending scientific data again. The probe and its twin, Voyager 2, are the only spacecraft to have ever flown in interstellar space (the space between stars).
Voyager 1 stopped sending readable science and engineering data to Earth on Nov. 14, 2023, even though mission controllers were able to say the spacecraft was still receiving its commands and operating normally.
In March, Voyager’s engineering team at the Jet Propulsion Laboratory (JPL) confirmed that the problem was related to one of the three computers aboard the spacecraft, called the flight data subsystem (FDS). The FDS is responsible for packaging scientific and engineering data before sending it to Earth.
The team discovered that a single chip responsible for storing a portion of the FDS’s memory, including some of the FDS’s computer software code, is not working. The loss of that code left scientific and engineering data unusable. Unable to repair the chip, the team decided to place the affected code elsewhere in the FDS memory. But no location is large enough to contain the entire code section. So they came up with a plan to divide the affected code into sections and store those sections in different places on the SDS.
For this plan to work, they also needed to adjust those sections of code to ensure, for example, that they all continued to work as a whole. Any references to the location of that code elsewhere in the FDS memory also needed to be updated.
The team began by identifying the code responsible for packaging the spacecraft’s engineering data. It was sent to its new location in the FDS memory on April 18. It takes about 22 and a half hours for a radio signal to reach Voyager 1, which is more than 15 billion miles from Earth, and another 22 and a half hours to receive a signal from the spacecraft on Earth. When the mission flight team heard back from the spacecraft on April 20, they saw that the modification was working: for the first time in five months, they were able to check the health and condition of the spacecraft.
Over the next few weeks, the team will relocate and adjust the other affected parts of the FDS software. These include the parts that will begin to return scientific data.
Voyager 2 continues to operate normally. Launched more than 46 years ago, the twin Voyager spacecraft are the most distant and operational in history. Before the start of their interstellar exploration, both probes flew by Saturn and Jupiter, and Voyager 2 flew by Uranus and Neptune.
