Voyager 1 is once again returning data from two of four science instruments onboard.

Updates:

(June 13, 2024) Another update to the code on one of Voyager 1's computers has brought the two remaining systems back online. Additional information can be found on NASA's Voyager blog.

The original story continues below.


Voyager
An artist's concept, of Voyager 1 in deep space.
NASA

Things are looking better for one of NASA’s longest running deep space missions. After a several-month period of problems, engineers have announced that the Voyager 1 spacecraft is not only back online but also transmitting useful data from two of four science instruments. Work is now underway to bring the remaining two instruments up to operational status.

Problems began last November, when Voyager 1 suddenly began sending a repeating gibberish signal instead of the science and engineering data it typically sends. Troubleshooting on the 46-year-old spacecraft revealed the culprit: a memory chip in one of the spacecraft’s three onboard computers was corrupted, perhaps due to a strike from a speedy charged particle known as a galactic cosmic ray. The corrupted chip in turn prevented communication with one of the probe's subsystems, known as the telemetry modulation unit.

Mission control
The Space Flight Operations Facility in Pasadena, California, which processes the signals sent from Voyager 1 as well as other spacecraft throughout the solar system, has changed a lot between 1964 and 2021. (Voyager 1 launched in 1977.)
NASA / JPL-Caltech

Without the ability to replace the chip, the team instead focused on a software-based workaround, moving affected code elsewhere. A key challenge was to find space to move the code, because no spot was large enough to hold the entire affected piece. The team broke the affected code into pieces and relocated them to different positions in the computer, while ensuring the code could still function as a whole. Also, any reference points to the affected code needed to be updated.

The first test of this approach was to focus on code for the spacecraft's engineering data. That modification was done on April 18th. Voyager 1 is currently 163 astronomical units away from Earth, and a signal takes 22.5 hours (45 hours round trip) to reach the spacecraft. The team thus had to wait two days to see if the fix had taken hold. When they finally saw that it had worked on April 20th, they once again had access to the general status of the spacecraft.

Additional updates allowed the spacecraft to resume sending back science data on May 17th from two of its instruments. Voyager 1’s magnetometer and plasma wave subsystem are now back to returning useful data.

Engineers are currently working to get two other systems back online: the low-energy charged particle instrument and the cosmic ray subsystem. Six other instruments are either no longer operational or were switched off after the spacecraft’s Saturn encounter in 1980.

A Long Mission, Nearly Lost

Voyager 1 has dodged disaster before, though of a different kind. After launch on September 5, 1977, an early shutdown of the second-stage engine nearly doomed Voyager 1. A longer burn of the Centaur stage just barely managed to correct the situation, with less than four seconds of fuel remaining.

It worked, though, and even though Voyager 1 was launched after Voyager 2, its more direct trajectory toward the outer solar system had it arrive at Jupiter and Saturn first. A close flyby of Titan, Saturn’s largest moon, ejected Voyager 1 out of the plane of the solar system in the direction of the constellation Ophiuchus.

Timeline
Voyager 1: A Timeline.
NASA

With both Voyager 1 and Voyager 2 having exited the solar system, their current mission objective is to explore the interstellar environment beyond the heliosphere, the region of space controlled by the Sun's magnetic field. Beyond the bow shock created by the solar wind, the spacecraft can chronicle the particles of the interstellar medium.

The Voyager spacecraft also both carry a copy of the Golden Record, a kind of time capsule with sounds and images from Earth for any would be alien salvagers that may come across the spacecraft.

Golden record
The Golden Record is a kind of time capsule sent along with both Voyager missions into interstellar space.
NASA / JPL

The Voyagers are two of five spacecraft escaping the solar system, along with New Horizons and the no longer operational Pioneers 10 and 11. Also headed outbound are the Star-37E/48B upper stage motors for each mission.

"For Voyager 1, the current power output is 220 watts. So Voyager 1 is currently producing a little less than 47% of its initial power," says Calla Cofield (NASA/JPL). "The probes both need about 200 watts to operate their antenna, so that's a big consumer onboard. The instruments each use about 4 watts of power each, and we lose about 4 watts of power each year."

With its plutonium fuel now just below half power, Voyager 1 is expected to continue operating through 2025, and it would be even more amazing to see the mission survive until the half-century mark in 2027. It represents humanity’s first footsteps out into the galaxy beyond.

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Comments


Image of Robert-LaPorta

Robert-LaPorta

May 31, 2024 at 3:00 pm

These 5 spacecraft shouldsurvive well past any structure built or existing in the solar system. I feel profoundly lucky being born at this time. When I was a child we did not know what the back of the moon looked like and had only fuzzy pictures of the other planets.

We are all around at a very special time!

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RC Silk

May 31, 2024 at 5:48 pm

R-LP wrote (in brief):> "These 5 spacecraft [should survive] well past any structure built or existing in the solar system."

Unless, of course, some Klingon decides to take pot-shots at one for target practice....

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RC Silk

May 31, 2024 at 5:51 pm

Besides which, the sun alone has an expected ~4.5 billion more years of life remaining. Do you suspect it's possible for those craft to have avoided interspace rubble during all that time?

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John

May 31, 2024 at 5:57 pm

I remember the fuzzy images we had of even the nearby planets in the 50's and 60's - now even amateurs with human-sized telescoes and digital cameras can make amazing images. My 1970-ish Saturn image was a fuzzy blob with ears, probably what Galileo first saw. My latest aren't what the elite imagers can do but a whole lot better than my 1970 image on film.

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Anthony Barreiro

June 1, 2024 at 12:49 am

According to wikipedia ( https://en.wikipedia.org/wiki/Voyager_program ), the original Voyager program cost $865 million, and the extended mission has cost an additional $30 million. This is less than we're spending on hubcaps for the Artemis mission to send humans to the Moon.

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Brian-Karas

June 1, 2024 at 10:04 am

It's amazing that these spacecraft are still operational. I worked on the Pioneer 10/11 missions and every day we set new records. We got to the point there in order to keep the HGA pointed toward the Earth we had to turn off the transmitter to fire the thruster, meaning we were maneuvering blind. The first time we did that we weren't even sure we could do it, because the TWTs had never been turned off in over 25 years. So many electrons had been boiled off of the helix coil we were afraid the thermal shock of turning it off and then back on would cause it to shatter. We contacted Watkins Johnson, who built the TWTs, for advice and even they didn't know, because nothing like this had ever been tried before. Fortunately it worked, and we all got to keep our jobs! So, congratulations to Voyager for stating alive this long!

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Gg

June 2, 2024 at 11:32 pm

Any idea why the plutonium power source is half depleted? The shortest lived isotope has a half life >6000 years.

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David Dickinson

June 3, 2024 at 4:51 am

I actually have a query on that oft-quoted stat out to researchers; spacecraft MMRTGs use Pu-238, which has a half-life of about ~88 years: https://en.wikipedia.org/wiki/Plutonium-238

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Gg

June 3, 2024 at 9:49 am

Thanks. I pulled a bad reference that gave the longer half-life. Stupid AI and me for believing it.

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David Dickinson

June 5, 2024 at 6:29 am

Never a problem... I actually got an answer back from NASA (now in the post) on the power situation for the Voyager spacecraft.

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