by After working for five months to re-establish communication with the longest human object in existence, NASA announced this week that the Voyager 1 probe had finally called home.
For the engineers and scientists who work on NASA’s longest-running mission in space, it was more intense joy and relief.
“That Saturday morning, we all came in, we’re sitting around boxes of donuts and waiting for the data to come back from Voyager,” said Linda Spilker, Voyager 1 mission project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California. “We knew exactly what time it was going to happen, and it got really quiet and everyone just sat there and they’re looking at the screen.”
When the spacecraft finally returned the agency’s long-awaited call, Spilker said the room erupted in celebration.
“There was cheering, people raising their hands,” she said. “And a sense of relief, too – that it was okay, after all this hard work and going from barely being able to get a signal from Voyager to being able to communicate again, what a great relief and it was a great feeling.”
Voyager 1 first discovered the problem in November. At the time, NASA said it was still in contact with the spacecraft and could see that it was receiving signals from Earth. But what was being sent back to mission controllers – including science data and information about the health of the probe and its various systems – was garbled and unreadable.
That began a months-long push to identify what happened and try to save Voyager 1’s mission.
Spilker said she and her colleagues remained hopeful and optimistic, but the team faced enormous challenges. In one case, engineers were trying to troubleshoot a spacecraft traveling in interstellar space, more than 15 billion miles away—the ultimate long-distance call.
“With Voyager 1, it takes 22 1/2 hours to get the signal up and 22 1/2 hours to get the signal back, so we’d get the commands ready, send them up, and then like for two days later, you must. “You would get the answer if it worked or if it didn’t work,” said Spilker.
The team eventually determined that the issue came from one of the three computers on board the spacecraft. Spilker said that hardware failure, perhaps as a result of age or being hit by radiation, likely messed up a small portion of the code in the computer’s memory. The glitch meant Voyager 1 was unable to send consistent updates about its health and science observations.
NASA engineers determined that they would not be able to repair the chip where the mangled software is stored. And the bad code was also too big for Voyager 1’s computer to store it and any new upload instructions. Because the technology on board Voyager 1 dates back to the 1960s and 1970s, the computer’s memory pales in comparison to any modern smartphone. Spilker said it is roughly equivalent to the amount of memory in an electronic car key.
However, the team found a workaround: They could divide the code into smaller parts and store them in different areas of the computer’s memory. Then, they could reprogram the part that needed to be fixed and make sure the whole system would still work cohesively.
That was quite an achievement, because the longevity of the Voyager mission means that there are no test beds or working simulators here on Earth to test the new pieces of code before they are sent to the spacecraft.
“Three different people were looking through the patch of code we were going to send up line by line, looking for anything they had missed,” Spilker said. “And so it was just one eye check on the software that we put up.”
The hard work paid off.
NASA reported the happy development on Monday, writing in a post on X: “Sounding a little more like yourself, #Voyager1.” The spacecraft’s own social media account responded, saying, “Hi, it’s me.”
So far, the team has determined that Voyager 1 is healthy and functioning normally. Spilker said the probe’s science instruments are on and appear to be working, but it will take some time for Voyager 1 to send back science data again.
Voyager 1 and its twin, the Voyager 2 probe, each launched in 1977 on missions to study the outer solar system. On its way through space, Voyager 1 flew past Jupiter and Saturn, studying the moons of nearby planets and snapping images along the way.
Voyager 2, which is 12.6 billion miles away, has had close encounters with Jupiter, Saturn, Uranus and Neptune and continues to function as usual.
In 2012, Voyager 1 advanced beyond the solar system, becoming the first man-made object to enter interstellar space, or the space between the stars. Voyager 2 followed suit in 2018.
Spilker, who first started working on the Voyager missions when she graduated college in 1977, said the missions could last into the 2030s. Eventually, however, the probes will run out of power or their components will be too old to continue working.
Spilker said it will be difficult to finally shut down the missions someday, but Voyager 1 and 2 will live on as “our silent ambassadors.”
Both explorers carry time capsules — messages on gold-plated copper discs collectively known as the Golden Record. The discs contain images and sounds that represent life on Earth and the culture of humanity, including snippets of music, animal sounds, laughter and greetings recorded in different languages. The idea is that the probes would carry the messages until future astronauts find them.
“Maybe in 40,000 years or so, they’ll be getting close enough to another star,” Spilker said, “and they could be found at that point.”
This article was originally published on NBCNews.com
