After working for five months to reestablish communication with the most distant man-made object in existence, NASA announced this week that the Voyager 1 probe finally called home.
For the engineers and scientists working on NASA’s longest-running space mission, it was a moment of joy and intense relief.
“That Saturday morning, we all walked in, sitting around boxes of donuts and waiting for the data to come back from Voyager,” said Linda Spilker, project scientist for the Voyager 1 mission at NASA’s Jet Propulsion Laboratory in Pasadena. California. “We knew exactly what time it was going to happen, and it was very quiet and everyone was just sitting there looking at the screen.”
When the spacecraft finally returned the agency’s call, Spilker said the room erupted in celebration.
“There was applause, people raising their hands,” she said. “And a sense of relief too – okay, after all this hard work and barely getting a signal from Voyager to be in communication again, it was a tremendous relief and a great feeling.”
The problem with Voyager 1 was first detected 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 transmitted to mission controllers – including scientific data and information about the status of the probe and its various systems – was distorted and unreadable.
This began a months-long effort to identify what went wrong and try to save Voyager 1’s mission.
Spilker said she and her colleagues remained hopeful and optimistic, but the team faced enormous challenges. On one hand, engineers were trying to troubleshoot a spacecraft traveling in interstellar spaceover 15 billion miles away — the best long-distance calling.
“With Voyager 1, it takes 22 and a half hours to get the signal and 22 and a half hours to get it back, so we would prepare the commands, send them, and two days later we would get the answer to whether it had worked or not,” Spilker said.
The team eventually determined that the problem came from one of the spacecraft’s three onboard computers. Spilker said a hardware failure, perhaps due to age or because it was hit by radiation, likely messed up a small section of code in the computer’s memory. The failure meant that Voyager 1 was unable to send back coherent updates on its scientific and health 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 both it and any newly uploaded instructions. Because the technology aboard Voyager 1 dates back to the 1960s and 1970s, the computer’s memory is puny compared to any modern smartphone. Spilker said it’s roughly equivalent to the amount of memory in an electronic car key.
The team found an alternative solution: they could divide the code into smaller parts and store them in different areas of the computer’s memory. Then, they could reprogram the section that needed fixing, while ensuring the entire system still worked cohesively.
This was quite a feat, because the longevity of the Voyager mission means that there are no test beds or simulators here on Earth to test the new bits of code before they are sent to the spacecraft.
“There were three different people going through the code patch we were going to ship line by line, looking for anything we had missed,” Spilker said. “And then it was kind of a visual check of the software that we shipped.”
The hard work paid off.
NASA reported the happy development on Monday, writing in a post on X: “Sounding a little more like you, #Voyager1.” The spaceship itself social media account respondedsaying, “Hi, it’s me.”
So far, the team has determined that Voyager 1 is healthy and operating normally. Spilker said the probe’s science instruments are powered on and appear to be working, but it will take some time for Voyager 1 to resume sending back science data.
Voyager 1 and its twin, the Voyager 2 probe, were launched in 1977 on missions to study the outer solar system. As it sped through the cosmos, Voyager 1 passed Jupiter and Saturn, studying the planets’ moons up close and taking images along the way.
Voyager 2, which is 20.2 billion kilometers away, has had close encounters with Jupiter, Saturn, Uranus and Neptune and continues to operate normally.
In 2012, Voyager 1 ventured 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 began working on the Voyager missions when he graduated from college in 1977, said the missions could last until 2030. Eventually, though, the probes will run out of power or their components will simply be too old to continue operating.
Spilker said it will someday be difficult to finally end the missions, but Voyager 1 and 2 will live on as “our silent ambassadors.”
Both probes carry time capsules – messages on gold-plated copper discs that are collectively known as The golden record. The discs contain images and sounds that represent life on Earth and the culture of humanity, including excerpts of music, animal sounds, laughter and greetings recorded in different languages. The idea is that the probes carry the messages until they are possibly found by space travelers in the distant future.
“Perhaps within 40,000 years or so, they will be relatively close to another star,” Spilker said, “and could be found at that point.”
This article was originally published in NBCNews. with
