For the first time in five months, NASA’s Voyager 1 spacecraft is returning usable data about the health and status of its onboard engineering systems. The next step is to enable the spacecraft to begin returning science data again. The probe and its twin, Voyager 2, are the only spacecraft to depart the Solar System and fly in interstellar space.
Voyager 1 stopped sending readable science and engineering data back to Earth on 14th November 2023, although ground controllers could tell the spacecraft was still receiving their commands and otherwise operating normally. In March, the Voyager engineering team at NASA’s Jet Propulsion Laboratory in Southern California confirmed that the issue was tied to one of the spacecraft’s three onboard computers, called the Flight Fata Subsystem (FDS). The FDS is responsible for packaging the science and engineering data before it’s sent to Earth.
The team discovered that a single chip responsible for storing a portion of the FDS memory — including some of the FDS computer’s software code — isn’t working. The loss of that code rendered the science and engineering data unusable. Unable to repair the chip, the team decided to place the affected code elsewhere in the FDS memory. But no single location is large enough to hold the section of code in its entirety.
So they devised a plan to divide the affected code into sections and store those sections in different places in the FDS. To make this plan work, they also needed to adjust those code sections to ensure that they all still function as a whole. Any references to the location of that code in other parts of the FDS memory needed to be updated as well.
The team started by singling out the code responsible for packaging the spacecraft’s engineering data. They sent it to its new location in the FDS memory on 18th April. A radio signal takes about 22.5 hours to reach Voyager 1, which is over 15 billion miles (24 billion kilometres) from Earth, and another 22.5 hours for a signal to come back to Earth. When the mission flight team heard back from the spacecraft on 20th April, they saw that the modification worked: For the first time in five months, they have been able to check the health and status of the spacecraft.
Voyager 2 continues to operate normally. Launched over 46 years ago, the twin Voyager spacecraft are the longest-running and most distant spacecraft from Earth in history. Before the start of their interstellar exploration, both probes flew by Saturn and Jupiter, and Voyager 2 flew by Uranus and Neptune.
Source: JPL News Release