Hurray! Voyager 1 has phoned home with engineering updates

Voyager 1: Group of people around a big table with laptops and papers on it. They are clapping and look happy.
After receiving data about the health and status of Voyager 1 for the first time in 5 months, members of the Voyager flight team celebrate in a conference room at NASA’s Jet Propulsion Laboratory on April 20. Image via NASA/ JPL-Caltech.
  • NASA’s Voyager 1 spacecraft has been traveling outward from Earth for 46 years and 7 months, as of today. It is now 15 billion miles (24 billion km) from Earth, making communications with its Earthly controllers nearly a 2-day round trip.
  • In November 2023, Voyager 1 began sending back only gibberish. As of late last month, the Voyager 1 team was trying various things to prompt the craft to respond, including a special command, called a “poke” by the team. Following the “poke,” the team was able to decipher a message from the spacecraft, although with difficulty.
  • Now Voyager 1 has begun sending an intelligible signal back to Earth again. The signal contains engineering updates. Scientists hope they can prompt the craft to resume sending science data again.

On April 22, 2024, Naomi Hartono posted this update on the status of Voyager 1 at NASA blogs. Edits by EarthSky.

Voyager 1 has phoned home

For the first time since November, 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 earthly spacecraft to ever fly in interstellar space (the space between stars).

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Voyager 1 stopped sending readable science and engineering data back to Earth on November 14, 2023, even though mission 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 data 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.

Here’s how they fixed it

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, for example, 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 April 18. A radio signal takes about 22 1/2 hours to reach Voyager 1, which is over 15 billion miles (24 billion kilometers) from Earth, and another 22 1/2 hours for a signal to come back to Earth. When the mission flight team heard back from the spacecraft on April 20, 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.

During the coming weeks, the team will relocate and adjust the other affected portions of the FDS software. These include the portions that will start returning science data.

Meanwhile, Voyager 1’s twin spacecraft – Voyager 2 – continues to operate normally. Launched over 46 years ago, the twin Voyager spacecraft are the longest-running and most distant spacecraft in history. Before the start of their interstellar exploration, both probes flew by Saturn and Jupiter, and Voyager 2 flew by Uranus and Neptune.

Bottom line: Now Voyager 1 has begun sending an intelligible signal back to Earth again. The signal contains engineering updates. Scientists hope they can prompt the craft to resume sending science data again.


April 23, 2024

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