NASA’s interstellar spacecraft, Voyager 1, is coming back online, the space agency announced on April 22.
After months of troubleshooting a glitch on Voyager 1 that caused the spacecraft to send home unusable data, the probe is working again and returning usable data about the health and status of its onboard engineering systems.
The next step, NASA said, is to enable the probe to begin returning science data.
NASA launched Voyager 1 — and later its twin Voyager 2 — in the summer of 1977 from Cape Canaveral, Fla., as part of a mission to explore interstellar space. In August 2012, Voyager 1 made its historic entry into interstellar space and beyond the influence of our Sun.
However, for the last year the probe has been experiencing several software and data glitches that could bring its mission to an end.
Engineers discovered a glitch on one of the probe’s three onboard computers, the flight data system (FDS). The FDS collects data – including engineering data about the health and status of the spacecraft. It then combines that information into a single data “package” which is sent back to Earth.
For the last year, the spacecraft has received and executed commands sent from Earth. However, the FDS was not communicating suitably with one of the probe’s subsystems – the telemetry modulation unit – and, as a result, it was returning distorted data.
The team attempted to fix the glitch by patching the software to prevent the recurrence of the glitch and prevent the issue from occurring again in Voyager 1 or arising in Voyager 2, but that that fix did not work.
Voyager 2 continues to operate normally.
Unable to repair the chip, the team placed the affected code elsewhere in the FDS memory because no single location was large enough to hold the section of code in its entirety.
According to NASA, the engineering team devised a plan to divide the affected code into sections and store those sections in different places in the FDS.
For the plan to work, the team needed to adjust those code sections to ensure they still function, and the location of that code in other parts of the FDS memory needed to be updated.
“The team started by singling out the code responsible for packaging the spacecraft’s engineering data,” according to a NASA statement.
The team sent the code to the new location in the FDS memory on April 18. The mission flight team heard back from the spacecraft on April 20, and the modification worked.
“For the first time in five months, they have been able to check the health and status of the spacecraft,” NASA said.
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.
