In May, NASA reported that its Voyager 1 spacecraft was sending strange data back to Earth.
After going through decades-old manuals to debug it, the Voyager team solved the problem in August.
Why this happened is still uncertain. Engineers believe this could be due to the spacecraft’s age or location in interstellar space.
In May, NASA scientists said the Voyager 1 spacecraft was returning inaccurate data from its attitude control system. In order to find a solution, engineers delved into decades-old textbooks.
The Voyager team resolved the mysterious issue in late August, NASA officials wrote in an update. It turns out the spacecraft was transmitting information using a dead computer that was corrupting the data.
Voyager 1, along with its twin Voyager 2, was launched in 1977 with a five-year lifespan to closely study Jupiter, Saturn, Uranus, Neptune and their respective moons.
After nearly 45 years in space, both spacecraft are still functioning. In 2012, Voyager 1 became the very first man-made object to venture beyond the limit of our sun’s influence, known as the heliopause, and into interstellar space. It is now about 14.8 billion kilometers from Earth and is sending data back beyond the solar system.
“No one thought it would last this long,” Suzanne Dodd, project manager for the Voyager mission at NASA’s Jet Propulsion Laboratory, told Insider over the summer before the Voyager team found a solution. adding, “And here we are.”
Digging up old spacecraft documents
Voyager 1 was designed and built in the early 1970s, complicating efforts to fix the spacecraft’s problems.
Although Voyager’s current engineers have documentation—or order media, the technical term for documents containing details of the spacecraft’s design and procedures—from those early mission days, other important documents may have been lost or misplaced.
During the first 12 years of the Voyager mission, thousands of engineers worked on the project, Dodd said. “When they retired in the 70s and 80s, there wasn’t a lot of pressure to have a library of project materials. People would take their boxes home to their garage,” Dodd added. In modern missions, NASA maintains stronger documentation records.
There are a few boxes with documents and schematics stored off-site from the Jet Propulsion Laboratory, and Dodd and the rest of Voyager’s handlers can request access to these records. Still, it can be a challenge. “To get that information, you need to figure out who’s working in that area on the project,” Dodd said.
For Voyager 1’s recent telemetry issue, mission engineers had to specifically search boxes under the names of engineers who helped design the attitude control system – which was “a time-consuming process. “Dodd said.
Origin of the bug
The spacecraft’s attitude control system, which feeds telemetry data back to NASA, indicates Voyager 1’s orientation in space and keeps the spacecraft’s high-gain antenna pointed at the Earth, allowing it to transmit the data home.
“Telemetry data is essentially a state of system health,” Dodd said. But during the glitch this summer, the telemetry readings spacecraft handlers were getting from the system were garbled, Dodd said, meaning they didn’t know if the attitude control system was working properly.
Dodd and his team had long suspected this was due to an aging part. “Not everything works forever, even in space,” she said over the summer.
Engineers also believed that Voyager’s problem might be influenced by its location in interstellar space. According to Dodd, data from the spacecraft suggests that high-energy charged particles are in interstellar space. “It’s unlikely anyone will hit the spacecraft, but if it did, it could cause more damage to the electronics,” Dodd said, adding, “We can’t pinpoint that as the source of the the anomaly, but that could be a factor.”
In late August, Voyager engineers located the source of the scrambled data: the spacecraft’s attitude control system was routing the information through a dead computer. They believe it was triggered by a faulty command from another on-board computer.
“We are pleased to have telemetry back,” Dodd said in a NASA statement released in August. Still, the team doesn’t know why this happened in the first place. “We will do a full memory read of the AACS and review everything it has done. This will help us try to diagnose the issue that caused the telemetry issue in the first place. So we’re cautiously optimistic, but we still have more investigations to do,” Dodd said in the statement.
Voyager 1’s journey continues
As part of an ongoing power management effort that has intensified in recent years, engineers have turned off non-technical systems aboard the Voyager probes, such as its science instrument heaters, in hopes of maintain them until 2030.
From the discovery of unknown moons and rings to the first direct evidence of the heliopause, the Voyager mission has helped scientists understand the cosmos. “We want the mission to last as long as possible, because science data is very valuable,” Dodd said.
“It’s really remarkable that both spacecraft are still working and working well – small issues, but working extremely well and still returning this valuable data,” Dodd said, adding, “They’re still talking to us.”
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