voyager 1 interstellar space sound

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Voyager 1 Presents the “Sounds” of Interstellar Space

By Dr. Tony Phillips, NASA Science November 8, 2013

A new ScienceCast video answers the question, what does interstellar space sound like?

Sci-Fi movies are sometimes criticized when explosions in the void make noise. As the old saying goes, “In space, no one can hear you scream.” Without air there is no sound.

But if that’s true, what was space physicist Don Gurnett talking about when he stated at a NASA press conference in September 2013 that he had heard “the sounds of interstellar space?”

It turns out that space can make music … if you know how to listen.

Gurnett is the James Van Allen professor of physics at the University of Iowa and the principal investigator for the Plasma Wave Science instrument on Voyager 1. At the press conference, he played some plasma wave data for the audience. The sounds, he explained, were solid evidence that Voyager 1 had left the heliosphere.

The heliosphere is a vast bubble of magnetism that surrounds the sun and planets. It is, essentially, the sun’s magnetic field inflated to enormous proportions by the solar wind. Inside the heliosphere is “home.” Outside lies interstellar space, the realm of the stars.

For decades, researchers have been on the edge of their seats, waiting for the Voyager probes to leave. Ironically, it took almost a year for NASA to realize the breakthrough had occurred. The reason is due to the slow cadence of transmissions from the distant spacecraft. Data stored on old-fashioned tape recorders are played back at three to six-month intervals. Then it takes more time to process the readings.

Gurnett recalls the thrill of discovery when some months-old data from the Plasma Wave Instrument reached his desk in the summer of 2013. The distant tones were conclusive: “Voyager 1 had made the crossing.”

Strictly speaking, the plasma wave instrument does not detect sound. Instead, it senses waves of electrons in the ionized gas or “plasma” that Voyager travels through. No human ear could hear these plasma waves. Nevertheless, because they occur at audio frequencies, between a few hundred and a few thousand hertz, “we can play the data through a loudspeaker and listen,” says Gurnett. “The pitch and frequency tell us about the density of gas surrounding the spacecraft.”

The frequency range shown from about 1.75 kiloHertz to 3.5 kiloHertz is a portion of the actual frequency range detected by PWS and is well within the audio frequency range. Importantly, the frequency is directly related to the number of electrons per unit volume in the vicinity of Voyager and corresponds to about 1 electron per 10 cubic centimeters or a cube about 1 inch on a side. The time scale for this presentation represents 225 days or a bit more than 7 months, while it only takes about 12 seconds to play the audio file. Hence, the time compression is about 1.6 million to one. It should be noted that this compression was done in such a way as to not change the frequencies.

In this animation, there are two events of interest. In the October-November 2012 time frame there is a tone near 2.1 kHz which gradually increases in frequency. Again, in the April-May 2013 time frame there is another event, somewhat more intense and at a higher frequency near 2.6 kHz. We conclude that these two events indicate an ongoing trend to higher frequencies. The second graphic frame which appears in the animation includes a dashed line showing this increase in frequency and suggests that the density of electrons is continually increasing over this time interval as Voyager moves outwards from the heliopause (which was crossed on 25 August 2012).

When Voyager 1 was inside the heliosphere, the tones were low, around 300 Hz, typical of plasma waves coursing through the rarified solar wind. Outside, the frequency jumped to a higher pitch, between 2 and 3 kHz, corresponding to denser gas in the interstellar medium. The transition music to Gurnett’s ears.

So far, Voyager 1 has recorded two outbursts of “interstellar plasma music”–one in Oct-Nov. 2012 and a second in April-May 2013. Both were excited by bursts of solar activity.

“We need solar events to trigger plasma oscillations,” says Gurnett.

The key players are CMEs, hot clouds of gas that blast into space when solar magnetic fields erupt. A typical CME takes 2 or 3 days to reach Earth, and a full year or more to reach Voyager. When a CME passes through the plasma, it excites oscillations akin to fingers strumming the strings on a guitar. Voyager’s Plasma Wave Instrument listens … and learns.

“We’re in a totally unexplored region of space,” says Gurnett. “I expect some surprises out there.”

In particular, Gurnett is hoping for plasma waves not excited by solar storms. He speculates that shock fronts from outside the solar system could be rippling through the interstellar medium. If so, they would excite new plasma waves that Voyager 1 will encounter as it plunges ever deeper into the realm of the stars.

The next “sounds” from out there could be surprising indeed.

Image: NASA/ JPL -Caltech

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2 comments on "voyager 1 presents the “sounds” of interstellar space".

It seems to me now would be a better chance to hear a signal transmission from ET, I hope someone is not just thinking the Noise is “Sounds of Interstellar Space” ! 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89……

Please note that “We need solar events to trigger plasma oscillations,”.. Here in this case the plasma oscillations are manipulated to give the sound effect as it videographs (or rather audiographs) the voyager 1 travel beyond Pluto in the rarefied solar particles field where the magnetic bursts from the Sun gives this electronic impulses, magnified to be heard as sound. But be sure that ET cannot give signal transmission to be felt. The so called signal transmission by ET was found to be none other than Cosmic Microwave Backround, which is the Doppler attenuation of Big Bang gamma radiations suffered due to the galloping galaxies. After such a long period the voyager has not completely left solar gravity zone since there is a Kuiper cloud still there with streaming asteroids and comets racing towards the Sun. Once it leaves solar gravity completely it will go towards the nearest star no doubt, which will also have the same complexion like ours.Thank You.

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• Published: 10 May 2021

Persistent plasma waves in interstellar space detected by Voyager 1

• Stella Koch Ocker   ORCID: orcid.org/0000-0002-4941-5333 1 ,
• James M. Cordes   ORCID: orcid.org/0000-0002-4049-1882 1 ,
• Shami Chatterjee   ORCID: orcid.org/0000-0002-2878-1502 1 ,
• Donald A. Gurnett   ORCID: orcid.org/0000-0003-2403-0282 2 ,
• William S. Kurth   ORCID: orcid.org/0000-0002-5471-6202 2 &
• Steven R. Spangler 2  

Nature Astronomy volume  5 ,  pages 761–765 ( 2021 ) Cite this article

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• Interstellar medium
• Space physics

In 2012, Voyager 1 became the first in situ probe of the very local interstellar medium 1 . The Voyager 1 Plasma Wave System has given point estimates of the plasma density spanning about 30 au of interstellar space, revealing a large-scale density gradient 2 , 3 and turbulence 4 outside of the heliopause. Previous studies of the plasma density relied on the detection of discrete plasma oscillation events triggered ahead of shocks propagating outwards from the Sun, which were used to infer the plasma frequency and, hence, density 5 , 6 . We present the detection of a class of very weak, narrowband plasma wave emission in the Voyager 1 data that persists from 2017 onwards and enables a steadily sampled measurement of the interstellar plasma density over about 10 au with an average sampling distance of 0.03 au. We find au-scale density fluctuations that trace interstellar turbulence between episodes of previously detected plasma oscillations. Possible mechanisms for the narrowband emission include thermally excited plasma oscillations and quasi-thermal noise, and they could be clarified by new findings from Voyager or a future interstellar mission. The emission’s persistence suggests that Voyager 1 may be able to continue tracking the interstellar plasma density in the absence of shock-generated plasma oscillation events.

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Data availability

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Acknowledgements

S.K.O., J.M.C., S.C. and S.R.S. acknowledge support from the National Aeronautics and Space Administration (NASA 80NSSC20K0784). S.K.O., J.M.C. and S.C. also acknowledge support from the National Science Foundation (NSF AAG-1815242) and are members of the NANOGrav Physics Frontiers Center, which is supported by the NSF award PHY-1430284. The research at the University of Iowa was supported by NASA through Contract 1622510 with the Jet Propulsion Laboratory.

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Stella Koch Ocker, James M. Cordes & Shami Chatterjee

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Donald A. Gurnett, William S. Kurth & Steven R. Spangler

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S.K.O. conducted the data analysis and wrote the initial draft of the paper. J.M.C., S.C., S.R.S. and S.K.O. are NASA Outer Heliosphere Guest Investigators on the Voyager Interstellar Mission. D.A.G. is the Principal Investigator of the Voyager PWS investigation and W.S.K. is a co-investigator of Voyager PWS and was responsible for the initial processing of the data at the University of Iowa. All authors contributed to the discussion of the results and commented on the draft.

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Ocker, S.K., Cordes, J.M., Chatterjee, S. et al. Persistent plasma waves in interstellar space detected by Voyager 1. Nat Astron 5 , 761–765 (2021). https://doi.org/10.1038/s41550-021-01363-7

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News | May 11, 2021

As nasa's voyager 1 surveys interstellar space, its density measurements are making waves.

Until recently, every spacecraft in history had made all of its measurements inside our heliosphere , the magnetic bubble inflated by our Sun. But on Aug. 25, 2012, NASA's Voyager 1 changed that. As it crossed the heliosphere's boundary , it became the first human-made object to enter – and measure – interstellar space. Now eight years into its interstellar journey, a close listen of Voyager 1's data is yielding new insights into what that frontier is like.

If our heliosphere is a ship sailing interstellar waters, Voyager 1 is a life raft just dropped from the deck, determined to survey the currents. For now, any rough waters it feels are mostly from our heliosphere's wake. But farther out, it will sense the stirrings from sources deeper in the cosmos. Eventually, our heliosphere's presence will fade from its measurements completely.

"We have some ideas about how far Voyager will need to get to start seeing more pure interstellar waters, so to speak," said Stella Ocker, a Ph.D. student at Cornell University in Ithaca, New York, and the newest member of the Voyager team. "But we're not entirely sure when we'll reach that point."

Ocker's new study, published on Monday in Nature Astronomy , reports what may be the first continuous measurement of the density of material in interstellar space. "This detection offers us a new way to measure the density of interstellar space and opens up a new pathway for us to explore the structure of the very nearby interstellar medium," Ocker said.

When one pictures the stuff between the stars – astronomers call it the "interstellar medium," a spread-out soup of particles and radiation – one might reimagine a calm, silent, serene environment. That would be a mistake.

"I have used the phrase ‘the quiescent interstellar medium' – but you can find lots of places that are not particularly quiescent," said Jim Cordes, space physicist at Cornell and co-author of the paper.

Like the ocean, the interstellar medium is full of turbulent waves. The largest come from our galaxy's rotation, as space smears against itself and sets forth undulations tens of light-years across. Smaller (though still gigantic) waves rush from supernova blasts, stretching billions of miles from crest to crest. The smallest ripples are usually from our own Sun, as solar eruptions send shockwaves through space that permeate our heliosphere's lining.

These crashing waves reveal clues about the density of the interstellar medium – a value that affects our understanding of the shape of our heliosphere, how stars form, and even our own location in the galaxy. As these waves reverberate through space, they vibrate the electrons around them, which ring out at characteristic frequencies depending on how crammed together they are. The higher the pitch of that ringing, the higher the electron density. Voyager 1's Plasma Wave Subsystem – which includes two "bunny ear" antennas sticking out 30 feet (10 meters) behind the spacecraft – was designed to hear that ringing.

An illustration of NASA's Voyager spacecraft showing the antennas used by the Plasma Wave Subsystem and other instruments. Credit: NASA/JPL-Caltech Full Image Details

In November 2012, three months after exiting the heliosphere, Voyager 1 heard interstellar sounds for the first time. Six months later, another "whistle" appeared – this time louder and even higher pitched. The interstellar medium appeared to be getting thicker, and quickly.

NASA's Voyager 1 spacecraft captured these sounds of interstellar space. Voyager 1's plasma wave instrument detected the vibrations of dense interstellar plasma, or ionized gas, from October to November 2012 and April to May 2013. Credit: NASA/JPL-Caltech

These momentary whistles continue at irregular intervals in Voyager's data today. They're an excellent way to study the interstellar medium's density, but it does take some patience.

"They've only been seen about once a year, so relying on these kind of fortuitous events meant that our map of the density of interstellar space was kind of sparse," Ocker said.

Ocker set out to find a running measure of interstellar medium density to fill in the gaps – one that doesn't depend on the occasional shockwaves propagating out from the Sun. After filtering through Voyager 1's data, looking for weak but consistent signals, she found a promising candidate. It started to pick up in mid-2017, right around the time of another whistle.

"It's virtually a single tone," said Ocker. "And over time, we do hear it change – but the way the frequency moves around tells us how the density is changing."

Weak but nearly continuous plasma oscillation events – visible as a thin red line in this graphic/tk – connect stronger events in Voyager 1's Plasma Wave Subsystem data. Use the slider to switch between graphs showing only the strong signals (blue background) and the filtered data showing weaker signals. Credit: NASA/JPL-Caltech/Stella Ocker

Ocker calls the new signal a plasma wave emission, and it, too, appeared to track the density of interstellar space. When the abrupt whistles appeared in the data, the tone of the emission rises and falls with them. The signal also resembles one observed in Earth's upper atmosphere that's known to track with the electron density there.

"This is really exciting, because we are able to regularly sample the density over a very long stretch of space, the longest stretch of space that we have so far," said Ocker. "This provides us with the most complete map of the density and the interstellar medium as seen by Voyager."

Based on the signal, electron density around Voyager 1 started rising in 2013 and reached its current levels about mid-2015, a roughly 40-fold increase in density. The spacecraft appears to be in a similar density range, with some fluctuations, through the entire dataset they analyzed which ended in early 2020.

Ocker and her colleagues are currently trying to develop a physical model of how the plasma wave emission is produced that will be key to interpreting it. In the meantime, Voyager 1's Plasma Wave Subsystem keeps sending back data farther and farther from home, where every new discovery has the potential to make us reimagining our home in the cosmos.

The Voyager spacecraft were built by NASA's Jet Propulsion Laboratory, which continues to operate both. JPL is a division of Caltech in Pasadena. The Voyager missions are a part of the NASA Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission Directorate in Washington.

For more information about the Voyager spacecraft, visit:

https://voyager.jpl.nasa.gov

News Media Contact

Calla Cofield Jet Propulsion Laboratory, Pasadena, Calif. 626-808-2469 [email protected] Written by Miles Hatfield 2021-101

Sound Of Interstellar Space Captured For First Time Ever By Voyager 1 Spacecraft (VIDEO)

Thanks to NASA's far-flung Voyager 1 spacecraft, now exploring the final frontier beyond our solar system, humanity can tune into the sounds of interstellar space.

Scientists announced today (Sept. 12) that Voyager 1 left the solar system in August 2012 after 35 years of spaceflight, making it the first craft ever to reach interstellar space. No other manmade object has ever travelled so far away from its home planet.

To mark the occasion, NASA unveiled the first Voyager 1 recording of the sound of interstellar space , offering the probe's strange, otherwordly take on its new frontier. The sounds are produced by the vibration of dense plasma, or ionized gas; they were captured by the probe's plasma wave instrument, NASA officials wrote in a video description. [ Voyager 1's Journey to Interstellar Space: A Photo Tour ]

"When you hear this recording, please recognize that this is an historic event. It's the first time that we've ever made a recording of sounds in interstellar space," Don Gurnett, principle investigator for the Voyager plasma wave investigation, said in a press conference today.

Researchers used the plasma data to infer that Voyager 1 first came into contact with the interstellar medium, effectively taking humanity between the stars, on or around Aug. 25, 2012.

"There were two times the instrument heard these vibrations: October to November 2012 and April to May 2013," NASA officials wrote. "Scientists noticed that each occurrence involved a rising tone. The dashed line indicates that the rising tones follow the same slope. This means a continuously increasing density."

Voyager 1's plasma sensor broke in 1980, so scientists had to get creative, and a little lucky, to figure this out. A massive solar eruption in March 2012 arrived at the location of Voyager 1 about 13 months later, making the plasma around the probe vibrate, NASA officials said.

That vibration helped researchers understand the density of the plasma, determining that it was 40 times more dense than measurements taken in the outer layer of the heliosphere, the bubble of charged particles and magnetic fields that the sun puffs out around itself.

The observed density matched up very well with what researchers expected to find in interstellar space.

"Now that we have new, key data, we believe this is mankind's historic leap into interstellar space," Ed Stone, Voyager project scientist based at the California Institute of Technology, Pasadena, Calif., said in a statement. "The Voyager team needed time to analyze those observations and make sense of them. But we can now answer the question we've all been asking — 'Are we there yet?' Yes, we are."

Voyager 1 launched on Sept. 5, 1977, about two weeks after its twin Voyager 2. The two spacecraft made it through their "grand tour" of the solar system, taking close-up looks at the Jupiter, Saturn, Uranus and Neptune systems. Their original mission ended in 1989, but the probes soldiered on, streaking through the unexplored regions at the outer reaches of the solar system.

The Voyager team still communicates with the two spacecraft every day, but the probes' extreme distances pose a challenge. At the speed of light, it takes about 17 hours for a message to reach Earth from Voyager 1, which is currently about 12 billion miles (19 billion kilometers) from the sun.

Follow Miriam Kramer @mirikramer and Google+ . Follow us @Spacedotcom , Facebook and Google+ . Original article on SPACE.com.

• Voyager 1 Records 'Sounds' From Interstellar Space | Video
• Voyager Welcomed To Interstellar Space | Video
• How the Voyager Space Probes Work (Infographic)
• Solar System Explored: Today's Deep-Space Spacecraft (Gallery)

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Launched in 1977, travelled passed the gas giant planets in our solar system and now off into interstellar space. It's a great journey.

We have an instrument on Voyager, which can measure the density of the ions, the plasma, which is out there.

In March of 2012 it turns out there was a massive eruption from the sun, which eventually reached Voyager 1 in April of 2013.

When that blast wave reached Voyager, it caused the plasma around Voyager to vibrate or oscillate in a certain particular tone.

Literally, they're the sounds of interstellar space.

(Sound of interstellar space)

And by measuring that sound wave, we could measure the density of the plasma and we're amazed to find out that we were in interstellar space.

This is a historic milestone in the great journeys of exploration that have been undertaken by humankind.

The Very Large Baseline Array took a radio image of Voyager 1 spacecraft slightly over 11-billion miles from the Earth.

And it's a very small radio dot amongst a sea of darkness.

It is quite remarkable when you think about it, that far off now at ever increasing differences, there's this little vehicle, two of them, which were built here many years ago and launched 36 years ago.

Now, on a journey that will basically last for billions of years.

NASA Jet Propulsion Laboratory, California Institute of Technology

14.1 billion miles from Earth, Voyager 1 detects a new cosmic "hum"

“And I was like, ‘am I starting to see things?’”

A weak but persistent signal from the Voyager 1 spacecraft at first seemed like a fluke to Cornell University Ph.D. candidate Stella Koch Ocker .

“I was literally just kind of staring at a plot, and I thought I saw something really faint,” Koch Ocker tells Inverse . “And I was like, ‘am I starting to see things?’”

She wasn’t. In a new study, Koch Ocker and colleagues report a new signal coming in from the Plasma Wave System instrument aboard the craft. They used these observations to obtain a new measurement of the density of the interstellar medium , the thinly distributed mix of molecules, atoms, and ionized gas or plasma that fills the space between stars.

The research , published Monday in the journal Nature Astrophysics, provides the first continuous measurement of the density of the plasma in the interstellar medium, which previously had only been known in isolated spots.

By looking back at the last three years of observations from Voyager 1, the researchers were able to assemble consistent measurements of this elusive interstellar plasma. They continue to monitor it as Voyager 1 speeds out of the Solar System at more than 38,000 miles per hour. It is approximately 14.1 billion miles from Earth.

What’s new — Prior methods of measuring the plasma density relied on picking up strong, intermittent bursts of signal from Voyager 1 , which seemed to occur about once every year. The intermittency of the signal made it akin to a once-a-year massive “storm” of large plasma oscillation events.

Emerging in data taken from 2017 to 2020, the new signal is only a few times stronger than the sensitivity of the instrument, making it barely noticeable. The Plasma Wave System allows Voyager 1 to measure vibrations of plasma at specific frequencies — the newly detected signal is a low-frequency “ hum ” at roughly 3 kHz.

And rather than being associated with intermittent events, the signal came across steadily over the entire duration of the three years, with little change in its character.

“When we looked between and below these plasma oscillation events, we found this very weak persistent signal of plasma waves that appears to not be related to solar activity,” says Koch Ocker.

The continuity of the new signal means the researchers can produce measurements of plasma density all along the trajectory of the spacecraft, rather than at the isolated locations of the “storms.” Discovering this trickle in the furthest reaches of space was almost entirely unexpected.

A 2016 NASA illustration of the various regions Voyager will pass through on its journey to parts unknown.

Here’s the background — Voyager 1 is one of two groundbreaking NASA missions launched in 1977 with a mission to explore the outer planets of the Solar System. Voyager 1 and 2 have obtained stunning pictures and information about the cosmos, and have both been in continuous contact with Earth since their launch. Voyager 1 is the most distant human-made object in space.

To accomplish these feats, mission planners took advantage of a particular alignment between the planets that happens only once every 175 years. This alignment allowed the spacecraft to consecutively slingshot between them purely through the use of natural, gravitational forces.

After their main missions ended in 1989, with Voyager 2’s encounter of Neptune, the craft were both transitioned to an interstellar phase on their path out of the Solar System. In 2012, Voyager 1 reached interstellar space — an area no longer dominated by the influence of the Sun.

Physicists always expected there to be tenuous plasma out there. Plasma is a phase of matter formed when a gas is heated so hot that its atoms and molecules are torn apart into their constituent ions and electrons. In the region of space closest to us, our solar neighborhood, plasma is formed with distinctive characteristics from the heat and radiation of the Sun.

Space isn’t a true void — it’s filled with stray molecules of gas and solid matter, which get turned by the Sun's heat and radiation into plasma.

Outside this bubble, known as the heliosphere, the plasma of the interstellar medium was expected to take on alternate characteristics. Voyager 1 showed exactly how.

A diagram of the Voyager spacecraft. The Plasma instrument on the top right is currently only functioning on Voyager 2.

How they did it — Prior to Voyager 1, researchers could only get clues on the interstellar plasma from observations with distant telescopes. But once Voyager 1 passed beyond the heliopause , separating the Sun’s neighborhood from interstellar space, it began registering direct signals from the plasma. These signals came in the form of occasional bursts of strong electrical discharge.

The bursts were detected by Voyager 1’s Plasma Wave System, one of the few instruments still operating on the craft. The Plasma Wave System works a bit like a voltage meter an electrician might use on a household electric outlet. (The spacecraft had a more robust plasma spectrometer that was defective on Voyager 1, though the one aboard Voyager 2 is still functioning.)

The occasional torrents of plasma picked up by the instrument were strong, like measuring a hundred pounds on a weight scale whose smallest measurement is one pound. Scientists gradually put together a picture of these signals as being caused by shock waves that occasionally barge out from the sun, making the plasma in the vicinity of the spacecraft vibrate, which in turn causes oscillations in its electric field.

However, when analyzing the overall electrical measurements collected from 2017 to 2020, researchers discovered a weak yet smooth signal hiding in the background of the data. Though this signal has the same fundamental electrical nature, it is more like a constant pitter-patter, rather than the occasional rush of a storm.

Why it matters — Both the strong, intermittent signals and the weak, steady signal provide important information on the nature of the interstellar plasma. In particular, the way that the plasma’s electric field fluctuates can be traced back directly to the plasma’s density.

Previously, researchers could only estimate the plasma’s density during the solar shock wave events. With the continuous data from the new signal, researchers can estimate the density of the plasma all along the spacecraft’s trajectory from 2017 to 2020. Moreover, the researchers find that the new density measurements are consistent with the old ones, having the same values when they were measured at the same time.

“It's pretty incredible how a mission that's so old can still produce such exciting new discoveries.”

The new results allow the researchers to turn a spotty record of plasma density with year-long gaps into a smooth, consistent record over space and time. The researchers find variations in the density with characteristic scales of 1 astronomical unit (AU), the distance between the earth and the sun. These variations have long been expected to arise due to turbulence in the interstellar medium.

The exact nature of the variations measured by the researchers will help inform whether the turbulence is primarily driven by huge, faraway sources like supernovae, or more local sources like the solar wind, Koch Ocker says.

What’s next — In addition to determining the nature of the interstellar turbulence, the researchers plan to find out more about the somewhat mysterious nature of the weak signal, which seemed to clearly emerge only in 2017, without any clear reason why.

For now, their best tool to attain further progress continues to be the 1970s era spacecraft of Voyager 1, the most loyal of probes, along with its sister probe of Voyager 2.

“It's pretty incredible how a mission that's so old can still produce such exciting new discoveries,” Koch Ocker says.

Abstract: In 2012, Voyager 1 became the first in situ probe of the very local interstellar medium 1 . The Voyager 1 Plasma Wave System has given point estimates of the plasma density spanning about 30 au of interstellar space, revealing a large-scale density gradient 2 , 3 and turbulence 4 outside of the heliopause. Previous studies of the plasma density relied on the detection of discrete plasma oscillation events triggered ahead of shocks propagating outwards from the Sun, which were used to infer the plasma frequency and, hence, density 5 , 6 . We present the detection of a class of very weak, narrowband plasma wave emission in the Voyager 1 data that persists from 2017 onwards and enables a steadily sampled measurement of the interstellar plasma density over about 10 au with an average sampling distance of 0.03 au. We find au-scale density fluctuations that trace interstellar turbulence between episodes of previously detected plasma oscillations. Possible mechanisms for the narrowband emission include thermally excited plasma oscillations and quasi-thermal noise, and they could be clarified by new findings from Voyager or a future interstellar mission. The emission’s persistence suggests that Voyager 1 may be able to continue tracking the interstellar plasma density in the absence of shock-generated plasma oscillation events.

This article was originally published on May 11, 2021

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Listen to What NASA's Voyager 1 Encountered in The Space Between Stars

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NASA launched Voyager 1, humanity’s first interstellar traveler, from Cape Canaveral on September 5, 1977. Monday marks the 45th anniversary of this momentous event.

Voyager’s original mission was to photograph Jupiter and Saturn, a 5-year assignment; but the unstoppable spacecraft continued to zip around the solar system and beyond, communicating with NASA and sending back data.

Voyager 1 crossed beyond the heliosphere into interstellar space in 2012. Not long after, it detected something and sent it back. A whistle. And then it picked up another one.

In this episode of KQED’s Audible Cosmos, we explore what Voyager encountered in that space between stars, and what else it might find on its journey.

• See how far away both Voyager 1 and Voyager 2 are right now
• Hear the original sound picked up by Voyager 1

Audible Cosmos is produced and reported by Amanda Font and Lowell Robinson, with original scoring by Lowell Robinson. 

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NASA spacecraft detects a constant 'hum' deep in the cosmos

Beyond the edge of the solar system, more than 14 billion miles from Earth, a NASA spacecraft has detected a curious and persistent "hum" in interstellar space.

The faint but constant vibrations were picked up by the Voyager 1 spacecraft , which, after more than four decades journeying deep into the cosmos, is the most distant human-made object in space. Scientists say the new discovery, published Monday in the journal Nature Astronomy , is providing a unique and never-before-seen glimpse of the interstellar environment — the frontier beyond the reaches of the sun and planets in our cosmic neighborhood.

"Voyager 1 is in an interesting region of space that is outside this thing called the heliosphere, which is the protective bubble that encases all the planets in the solar system," said Stella Ocker, a doctoral student at Cornell University in Ithaca, New York, and one of the authors of the new study. "So, it's really our only tool for directly sampling the nature of interstellar space."

Ocker and her colleagues don't yet know what's causing the "hum," but it was measured through ripples of plasma in what's known as the interstellar medium, the hodgepodge of gas, radiation and particles that make up the space between stars. While it's not an actual audio signal, the faint drone showed up as vibrations in a narrow frequency bandwidth, Ocker said.

Previously, scientists could only take fleeting measurements of the interstellar medium after periodic but isolated eruptions from the sun, which would unleash shockwaves that coursed through the solar system and beyond.

The new findings suggest that by tracking these persistent vibrations in the interstellar medium, it may be possible to tease out specific properties of this environment, such as its density. This, in turn, will help astronomers better understand the mysterious environment beyond the solar system.

"Rather than trying to map the geography around my house based on one or two trees in my yard, this will let me map all the way from my house to the next neighborhood," said Merav Opher, a professor of astronomy at Boston University who was not involved with the new research.

Voyager 1 crossed into interstellar space in 2012, but the plasma "hum" was first detected in 2017, Ocker said. It's not yet understood why the signal didn't appear sooner or what that lag could mean, she added.

The scientists are also keen to see whether the persistent drone continues as the probe travels deeper through interstellar space.

Opher called the new findings "phenomenal," because they could reveal much about how the cocoon-like magnetic bubble around the solar system interacts with what lies beyond it.

There are questions, for instance, about how much the sun's activity shapes the solar system's protective cocoon and interacts with the interstellar medium.

"It's almost 10 years now that Voyager 1 has been in interstellar space, and we see that the influence of the sun is still pretty strong," Opher said.

Voyager 1, and its twin Voyager 2 probe, were launched in 1977. Both spacecraft flew past all of the giant planets in the outer solar system before crossing the heliosphere's boundary. Voyager 1 entered interstellar space in 2012, and Voyager 2 followed in 2018 .

Ocker said the new research is a testament to the pioneering Voyager 1 mission, which continues to beam back data 44 years after its launch.

"It’s the engineering gift to science that keeps on giving," she said.

Denise Chow is a reporter for NBC News Science focused on general science and climate change.

The farthest spacecraft from Earth has detected a 'hum' in the space beyond our solar system

• NASA's Voyager 1 probe has detected a faint, constant hum in the space beyond our solar system.
• When charged gas ripples through interstellar space, those ripples emit a detectable vibration.
• The Voyager 1 spacecraft left Earth more than 40 years ago and entered interstellar space in 2012.

More than 14 billion miles from Earth, NASA's Voyager 1 spacecraft is listening to the background music of interstellar space.

The probe, which launched more than 40 years ago, exited our solar system in 2012. Five years after its interstellar foray began, Voyager 1 began picking up a monotonous droning.  

According to a study published Monday in the journal Nature Astronomy , the spacecraft is detecting the constant burble of charged gas, known as plasma. The sound is created as this plasma ripples through the interstellar medium — a soup of radiation, gaseous particles, and dust that fills the space between stars.

"We're detecting the faint, persistent hum of interstellar gas," Stella Koch Ocker, a Cornell University astronomer and co-author of the new study, said in a release .

The humming would not be audible to the human ear, Ocker said, but Voyager 1's onboard instruments can pick up the vibrations.

"If we could hear it, it would sound like a single steady note, playing constantly but changing very slightly over time," she told Reuters .

Related stories

Keeping tabs on those vibrations as Voyager 1 travels further could help astronomers learn more about what interstellar space is like, and whether the mixture of gas and radiation differs from place to place in the universe.

'A quiet or gentle rain'

Voyager 1 has traveled farther from Earth than any other spacecraft in history. It's one of only two human-made objects that have ever crossed into interstellar space — the other i sits counterpart, Voyager 2 , which left the solar system in 2018.

NASA launched the twin Voyagers in 1977 to swing around Jupiter and Saturn over the course of a 5-year mission. The spacecraft taught astronomers about the composition of Saturn's rings and the existence of volcanoes on Jupiter's moon, Io. Then Voyager 2 went on to visit Uranus and Neptune, while Voyager 1 continued on toward the edge of our solar system.

To truly reach interstellar space, both Voyager probes had to cross the heliopause — the outer boundary of the stream of charged particles shot out by the sun. This solar wind, as the stream is known, extends beyond our solar system, but at the heliopause , it encounters pressure from the wind in interstellar space and gets turned back toward the sun.

Research suggests the sun's influence can sometimes extend beyond the heliopause, though. Occasionally, the sun spits out billions of tons of charged particles from its atmosphere in the form of solar flares. These eruptions can cause violent disturbances in interstellar gas. Voyager 1 has detected such shockwaves before.

But the farther into the heliopause Voyager 1 goes, the less the sun's energy should ooze into the interstellar medium and push or pull on the gas therein.

According to NASA , there will come a point in Voyager 1's travels when solar particles no longer influence its measurements. Once the probe gets there, "it will sense the stirrings from sources deeper in the cosmos," the agency said.

Indeed, the humming outlined in the new study seems unrelated to what the sun is doing — unlike those erratic shockwaves, this is a constant vibration in the interstellar medium, which suggests a different source of energy that astronomers might not know about yet.

"The interstellar medium is like a quiet or gentle rain," James Cordes, a Cornell astronomer and another study co-author, said in the release. "In the case of a solar outburst, it's like detecting a lightning burst in a thunderstorm and then it's back to a gentle rain."

Listening for the hum of that gentle rain could help researchers better understand how dense the space between stars is — and whether that density changes — as Voyager 1 gets farther and farther from Earth. It could also reveal clues about how and where the most stellar nurseries are, since stars form in high-density interstellar clouds.

Watch: NASA is flying a $1.5 billion spacecraft into the sun — here's why

• Main content

The most distant human-made object

No spacecraft has gone farther than NASA's Voyager 1. Launched in 1977 to fly by Jupiter and Saturn, Voyager 1 crossed into interstellar space in August 2012 and continues to collect data.

Mission Type

What is Voyager 1?

Voyager 1 has been exploring our solar system for more than 45 years. The probe is now in interstellar space, the region outside the heliopause, or the bubble of energetic particles and magnetic fields from the Sun.

• Voyager 1 was the first spacecraft to cross the heliosphere, the boundary where the influences outside our solar system are stronger than those from our Sun.
• Voyager 1 is the first human-made object to venture into interstellar space.
• Voyager 1 discovered a thin ring around Jupiter and two new Jovian moons: Thebe and Metis.
• At Saturn, Voyager 1 found five new moons and a new ring called the G-ring.

In Depth: Voyager 1

Voyager 1 was launched after Voyager 2, but because of a faster route, it exited the asteroid belt earlier than its twin, having overtaken Voyager 2 on Dec. 15, 1977.

Voyager 1 at Jupiter

Voyager 1 began its Jovian imaging mission in April 1978 at a range of 165 million miles (265 million km) from the planet. Images sent back by January the following year indicated that Jupiter’s atmosphere was more turbulent than during the Pioneer flybys in 1973–1974.

Beginning on January 30, Voyager 1 took a picture every 96 seconds for a span of 100 hours to generate a color timelapse movie to depict 10 rotations of Jupiter. On Feb. 10, 1979, the spacecraft crossed into the Jovian moon system and by early March, it had already discovered a thin (less than 30 kilometers thick) ring circling Jupiter.

Voyager 1’s closest encounter with Jupiter was at 12:05 UT on March 5, 1979 at a range of about 174,000 miles (280,000 km). It encountered several of Jupiter’s Moons, including Amalthea, Io, Europa, Ganymede, and Callisto, returning spectacular photos of their terrain, opening up completely new worlds for planetary scientists.

The most interesting find was on Io, where images showed a bizarre yellow, orange, and brown world with at least eight active volcanoes spewing material into space, making it one of the most (if not the most) geologically active planetary body in the solar system. The presence of active volcanoes suggested that the sulfur and oxygen in Jovian space may be a result of the volcanic plumes from Io which are rich in sulfur dioxide. The spacecraft also discovered two new moons, Thebe and Metis.

Voyager 1 at Saturn

Following the Jupiter encounter, Voyager 1 completed an initial course correction on April 9, 1979 in preparation for its meeting with Saturn. A second correction on Oct. 10, 1979 ensured that the spacecraft would not hit Saturn’s moon Titan.

Its flyby of the Saturn system in November 1979 was as spectacular as its previous encounter. Voyager 1 found five new moons, a ring system consisting of thousands of bands, wedge-shaped transient clouds of tiny particles in the B ring that scientists called “spokes,” a new ring (the “G-ring”), and “shepherding” satellites on either side of the F-ring—satellites that keep the rings well-defined.

During its flyby, the spacecraft photographed Saturn’s moons Titan, Mimas, Enceladus, Tethys, Dione, and Rhea. Based on incoming data, all the moons appeared to be composed largely of water ice. Perhaps the most interesting target was Titan, which Voyager 1 passed at 05:41 UT on November 12 at a range of 2,500 miles (4,000 km). Images showed a thick atmosphere that completely hid the surface. The spacecraft found that the moon’s atmosphere was composed of 90% nitrogen. Pressure ad temperature at the surface was 1.6 atmospheres and 356 °F (–180°C), respectively.

Atmospheric data suggested that Titan might be the first body in the solar system (apart from Earth) where liquid might exist on the surface. In addition, the presence of nitrogen, methane, and more complex hydrocarbons indicated that prebiotic chemical reactions might be possible on Titan.

Voyager 1’s closest approach to Saturn was at 23:46 UT on 12 Nov. 12, 1980 at a range of 78,000 miles(126,000 km).

Voyager 1’s ‘Family Portrait’ Image

Following the encounter with Saturn, Voyager 1 headed on a trajectory escaping the solar system at a speed of about 3.5 AU per year, 35° out of the ecliptic plane to the north, in the general direction of the Sun’s motion relative to nearby stars. Because of the specific requirements for the Titan flyby, the spacecraft was not directed to Uranus and Neptune.

The final images taken by the Voyagers comprised a mosaic of 64 images taken by Voyager 1 on Feb. 14, 1990 at a distance of 40 AU of the Sun and all the planets of the solar system (although Mercury and Mars did not appear, the former because it was too close to the Sun and the latter because Mars was on the same side of the Sun as Voyager 1 so only its dark side faced the cameras).

This was the so-called “pale blue dot” image made famous by Cornell University professor and Voyager science team member Carl Sagan (1934-1996). These were the last of a total of 67,000 images taken by the two spacecraft.

Voyager 1’s Interstellar Mission

All the planetary encounters finally over in 1989, the missions of Voyager 1 and 2 were declared part of the Voyager Interstellar Mission (VIM), which officially began on Jan. 1, 1990.

The goal was to extend NASA’s exploration of the solar system beyond the neighborhood of the outer planets to the outer limits of the Sun’s sphere of influence, and “possibly beyond.” Specific goals include collecting data on the transition between the heliosphere, the region of space dominated by the Sun’s magnetic field and solar field, and the interstellar medium.

On Feb. 17, 1998, Voyager 1 became the most distant human-made object in existence when, at a distance of 69.4 AU from the Sun when it “overtook” Pioneer 10.

On Dec. 16, 2004, Voyager scientists announced that Voyager 1 had reported high values for the intensity for the magnetic field at a distance of 94 AU, indicating that it had reached the termination shock and had now entered the heliosheath.

The spacecraft finally exited the heliosphere and began measuring the interstellar environment on Aug. 25, 2012, the first spacecraft to do so.

On Sept. 5, 2017, NASA marked the 40th anniversary of its launch, as it continues to communicate with NASA’s Deep Space Network and send data back from four still-functioning instruments—the cosmic ray telescope, the low-energy charged particles experiment, the magnetometer, and the plasma waves experiment.

The Golden Record

Each of the Voyagers contain a “message,” prepared by a team headed by Carl Sagan, in the form of a 12-inch (30 cm) diameter gold-plated copper disc for potential extraterrestrials who might find the spacecraft. Like the plaques on Pioneers 10 and 11, the record has inscribed symbols to show the location of Earth relative to several pulsars.

The records also contain instructions to play them using a cartridge and a needle, much like a vinyl record player. The audio on the disc includes greetings in 55 languages, 35 sounds from life on Earth (such as whale songs, laughter, etc.), 90 minutes of generally Western music including everything from Mozart and Bach to Chuck Berry and Blind Willie Johnson. It also includes 115 images of life on Earth and recorded greetings from then U.S. President Jimmy Carter (1924– ) and then-UN Secretary-General Kurt Waldheim (1918–2007).

By January 2024, Voyager 1 was about 136 AU (15 billion miles, or 20 billion kilometers) from Earth, the farthest object created by humans, and moving at a velocity of about 38,000 mph (17.0 kilometers/second) relative to the Sun.

National Space Science Data Center: Voyager 1

A library of technical details and historic perspective.

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A comprehensive history of missions sent to explore beyond Earth.

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This gives hope that the spacecraft can be fixed and resume its operations.

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The Voyager 1 spacecraft is finally giving us a clue as to what went wrong.

Image Credit: Caltech/NASA-JPL modified by IFLScience

The farthest human-built object is in trouble. Voyager 1 is 24 billion kilometers (15 billion miles) from our planet, flying through interstellar space, and over the last several months NASA has not been able to properly communicate with it. But a first step towards a solution has been achieved. The engineering team has recognized a message within the stream of 0s and 1s coming from the spacecraft.

“In September 2023, an issue arose with the data coming back from Voyager 1. Normally transmitted in binary code, or a series of 0s and 1s representing words, the probe was instead sending only alternating 1s and 0s . Effectively, the call between the spacecraft and the Earth was still connected, but Voyager’s 'voice' was replaced with a monotonous dial tone,” the NASA Voyager engineering team explained to IFLScience in February .

“Because of this issue, scientists are not receiving any science data or updates about the probe’s health and status, including information that might reveal the source of the problem. Through various indirect means, the team has concluded that the issue is most likely with the Flight Data System [FDS], one of the probe’s onboard computers. The team is working hard to resolve the issue, but this process may take months.”

Several approaches were attempted but something changed early this month. On March 1, the engineering team sent a poke – a command designed to force the FDS to try different sequences within its software package – just in case there is a corrupted section and it can be bypassed.

Voyager 1 is 22 light-hours and 34 light-minutes away , so it took almost a day for the signal to get there and almost a day for something to get back to NASA. The poke did not solve the problem but it did something for sure.

“On March 3, the Voyager mission team saw activity from one section of the FDS that differed from the rest of the computer’s unreadable data stream. The new signal was still not in the format used by Voyager 1 when the FDS is working properly, so the team wasn’t initially sure what to make of it,” the Voyager team wrote in a blog post .

 “But an engineer with the agency’s Deep Space Network, which operates the radio antennas that communicate with both Voyagers and other spacecraft traveling to the Moon and beyond, was able to decode the new signal and found that it contains a readout of the entire FDS memory.”

The FDS memory contains not just its code but also data about the status of the spacecraft. The team is now comparing this data with data received before September to work out what might have happened and how it could be fixed.

“There is no backup FDS, so if the team cannot fix this issue, it would likely be the end of operations for Voyager 1. However, Voyager 2 is operating nominally; the Voyager mission will continue as long as one probe is still working,” the Voyager team told IFLScience previously. 

NASA’s planned budget for the coming years shows commitment to keeping the Voyager mission going well past its 50th anniversary in 2027.

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Voyager 1, First Craft in Interstellar Space, May Have Gone Dark

The 46-year-old probe, which flew by Jupiter and Saturn in its youth and inspired earthlings with images of the planet as a “Pale Blue Dot,” hasn’t sent usable data from interstellar space in months.

By Orlando Mayorquin

When Voyager 1 launched in 1977, scientists hoped it could do what it was built to do and take up-close images of Jupiter and Saturn. It did that — and much more.

Voyager 1 discovered active volcanoes, moons and planetary rings, proving along the way that Earth and all of humanity could be squished into a single pixel in a photograph, a “ pale blue dot, ” as the astronomer Carl Sagan called it. It stretched a four-year mission into the present day, embarking on the deepest journey ever into space.

Now, it may have bid its final farewell to that faraway dot.

Voyager 1 , the farthest man-made object in space, hasn’t sent coherent data to Earth since November. NASA has been trying to diagnose what the Voyager mission’s project manager, Suzanne Dodd, called the “most serious issue” the robotic probe has faced since she took the job in 2010.

The spacecraft encountered a glitch in one of its computers that has eliminated its ability to send engineering and science data back to Earth.

The loss of Voyager 1 would cap decades of scientific breakthroughs and signal the beginning of the end for a mission that has given shape to humanity’s most distant ambition and inspired generations to look to the skies.

“Scientifically, it’s a big loss,” Ms. Dodd said. “I think — emotionally — it’s maybe even a bigger loss.”

Voyager 1 is one half of the Voyager mission. It has a twin spacecraft, Voyager 2.

Launched in 1977, they were primarily built for a four-year trip to Jupiter and Saturn , expanding on earlier flybys by the Pioneer 10 and 11 probes.

The Voyager mission capitalized on a rare alignment of the outer planets — once every 175 years — allowing the probes to visit all four.

Using the gravity of each planet, the Voyager spacecraft could swing onto the next, according to NASA .

The mission to Jupiter and Saturn was a success.

The 1980s flybys yielded several new discoveries, including new insights about the so-called great red spot on Jupiter, the rings around Saturn and the many moons of each planet.

Voyager 2 also explored Uranus and Neptune , becoming in 1989 the only spacecraft to explore all four outer planets.

Voyager 1, meanwhile, had set a course for deep space, using its camera to photograph the planets it was leaving behind along the way. Voyager 2 would later begin its own trek into deep space.

“Anybody who is interested in space is interested in the things Voyager discovered about the outer planets and their moons,” said Kate Howells, the public education specialist at the Planetary Society, an organization co-founded by Dr. Sagan to promote space exploration.

“But I think the pale blue dot was one of those things that was sort of more poetic and touching,” she added.

On Valentine’s Day 1990, Voyager 1, darting 3.7 billion miles away from the sun toward the outer reaches of the solar system, turned around and snapped a photo of Earth that Dr. Sagan and others understood to be a humbling self-portrait of humanity.

“It’s known the world over, and it does connect humanity to the stars,” Ms. Dodd said of the mission.

She added: “I’ve had many, many many people come up to me and say: ‘Wow, I love Voyager. It’s what got me excited about space. It’s what got me thinking about our place here on Earth and what that means.’”

Ms. Howells, 35, counts herself among those people.

About 10 years ago, to celebrate the beginning of her space career, Ms. Howells spent her first paycheck from the Planetary Society to get a Voyager tattoo.

Though spacecraft “all kind of look the same,” she said, more people recognize the tattoo than she anticipated.

“I think that speaks to how famous Voyager is,” she said.

The Voyagers made their mark on popular culture , inspiring a highly intelligent “Voyager 6” in “Star Trek: The Motion Picture” and references on “The X Files” and “The West Wing.”

Even as more advanced probes were launched from Earth, Voyager 1 continued to reliably enrich our understanding of space.

In 2012, it became the first man-made object to exit the heliosphere, the space around the solar system directly influenced by the sun. There is a technical debate among scientists around whether Voyager 1 has actually left the solar system, but, nonetheless, it became interstellar — traversing the space between stars.

That charted a new path for heliophysics, which looks at how the sun influences the space around it. In 2018, Voyager 2 followed its twin between the stars.

Before Voyager 1, scientific data on the sun’s gases and material came only from within the heliosphere’s confines, according to Dr. Jamie Rankin, Voyager’s deputy project scientist.

“And so now we can for the first time kind of connect the inside-out view from the outside-in,” Dr. Rankin said, “That’s a big part of it,” she added. “But the other half is simply that a lot of this material can’t be measured any other way than sending a spacecraft out there.”

Voyager 1 and 2 are the only such spacecraft. Before it went offline, Voyager 1 had been studying an anomalous disturbance in the magnetic field and plasma particles in interstellar space.

“Nothing else is getting launched to go out there,” Ms. Dodd said. “So that’s why we’re spending the time and being careful about trying to recover this spacecraft — because the science is so valuable.”

But recovery means getting under the hood of an aging spacecraft more than 15 billion miles away, equipped with the technology of yesteryear. It takes 45 hours to exchange information with the craft.

It has been repeated over the years that a smartphone has hundreds of thousands of times Voyager 1’s memory — and that the radio transmitter emits as many watts as a refrigerator lightbulb.

“There was one analogy given that is it’s like trying to figure out where your cursor is on your laptop screen when your laptop screen doesn’t work,” Ms. Dodd said.

Her team is still holding out hope, she said, especially as the tantalizing 50th launch anniversary in 2027 approaches. Voyager 1 has survived glitches before, though none as serious.

Voyager 2 is still operational, but aging. It has faced its own technical difficulties too.

NASA had already estimated that the nuclear-powered generators of both spacecrafts would likely die around 2025.

Even if the Voyager interstellar mission is near its end, the voyage still has far to go.

Voyager 1 and its twin, each 40,000 years away from the next closest star, will arguably remain on an indefinite mission.

“If Voyager should sometime in its distant future encounter beings from some other civilization in space, it bears a message,” Dr. Sagan said in a 1980 interview .

Each spacecraft carries a gold-plated phonograph record loaded with an array of sound recordings and images representing humanity’s richness, its diverse cultures and life on Earth.

“A gift across the cosmic ocean from one island of civilization to another,” Dr. Sagan said.

Orlando Mayorquin is a general assignment and breaking news reporter based in New York. More about Orlando Mayorquin

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March 14, 2024

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Voyager 1’s Immortal Interstellar Requiem

NASA is reaching across more than 15 billion miles to rescue its malfunctioning Voyager 1 probe—but this hallowed interstellar mission can’t live forever

By Nadia Drake

An artist's concept of NASA's Voyager 1, the space agency's venerable and farthest-flung interplanetary probe.

Mark Garlick/Science Photo Library

In the fall of last year, one of NASA’s most venerable spacecraft started beaming home nonsense. Its usual string of 1’s and 0’s—binary code that collectively told of its journey into the unknown—became suddenly unintelligible.

Some 15 billion miles from Earth, beyond the protective bubble blown by the sun and in interstellar space, Voyager 1 was in trouble.

“We’d gone from having a conversation with Voyager, with the 1’s and 0’s containing science data, to just a dial tone,” says Linda Spilker , Voyager project scientist at NASA’s Jet Propulsion Laboratory (JPL).

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Spilker joined JPL in 1977, the same year that NASA launched Voyager 1 and its twin, Voyager 2 , on what, in a way, was an endless odyssey: from Earth, to the outer solar system and ultimately to interstellar infinity . Today there are several billion people on Earth who have never taken a breath without the Voyagers in our sky, people who, like me, have only ever existed in a cosmos shared with these talkative twin spacecraft. But like people, spacecraft get old. They break down .

And all good things—and even great ones—must come to an end. After days, and weeks and then months of nothing but indecipherable binary babbling, Voyager 1’s earthbound stewards had to reckon with the idea that maybe, after more than 46 years, its time had at last run out.

The Voyager 1 team at JPL had traced the problem to the spacecraft’s Flight Data System, an onboard computer that parses and parcels engineering and science measurements for subsequent radio transmittal to Earth. One possibility was that a high-energy cosmic particle had struck Voyager 1 and caused a bit flip within the system’s memory — something that has happened more frequently as the craft navigates the hostile wilds of interstellar space. Normally, the team would simply ask the spacecraft for a memory readout, allowing its members to find and reset the errant bit.

“We’ve recovered from bit flips before. The problem this time is we don’t know where the bit flip is because we can’t see what the memory is,” says Suzanne Dodd , Voyager project manager at JPL, who, like Spilker, began her long career with work on the probes. “It’s the most serious issue we’ve had since I’ve been the project manager, and it’s scary because you lose communication with the spacecraft.”

Yesterday, the team announced a significant step in breaking through to Voyager 1. After months of stress and unsuccessful answers they have managed to decode at least a portion of the spacecraft’s gobbledygook, allowing them to (maybe) find a way to see what it has been trying to say.

“It’s an excellent development on Voyager,” says Joe Westlake , director of NASA’s heliophysics division, which oversees the mission.

In the time it will take you to read this story, Voyager 1 will have traversed approximately 10,000 miles of mostly empty space ; in the weeks it took me to report it, the probe traveled some 26 million miles. And since its communication first became garbled last November, the spacecraft has sailed another 10 light-minutes away from home. Voyager 1 and its twin are slipping away from us as surely as the passage of time itself. Sooner or later, these hallowed space-age icons will fall silent, becoming no more than distant memories.

And even among the space community, which of course loves all of its robotic explorers equally, the Voyagers are special. “They are incredibly important and much beloved spacecraft,” says Nicola Fox , NASA’s associate administrator for science. “Voyager 1 is a national treasure, along with Voyager 2 .”

As envisioned, the Voyager mission would exploit a once-in-175-year alignment of Jupiter, Saturn, Uranus and Neptune to slingshot through the solar system’s sparsely charted hinterlands. Legend has it that NASA’s administrator sold the project to President Richard Nixon by noting that the last time the planets were so favorably arranged, Thomas Jefferson was living in the White House. Outfitted with nuclear power sources, the Voyagers were built to last—in utter defiance of the adage that what must go up, must come down. Neither was ever intended to make planetfall again; instead they were bound for the stars. And now, nearly a half-century later, the pair have become the longest-lived and farthest-flung probes ever dispatched by humankind. (Voyager 1 is the front-runner, with its sibling trailing close behind.)

Spilker was straight out of college when she started working on the Voyagers, eager to see the outer solar system through their robotic eyes as they surfed the rare celestial alignment. “I had a telescope in third grade that I used to look at Jupiter and Saturn,” she says. “I wanted to get up really close and get a look at what these planets look like.”

Between 1979 and 1981, Voyager 1 and Voyager 2 zipped by the gas giants , returning stunning images of banded Jupiter and buttery Saturn and their bewildering collection of moons. Voyager 2 went on to scrutinize the ice giants: Uranus in 1986 and Neptune in 1989. These were the first and only times anyone had seen each of these bluish ringed worlds up close.

“They were small little pinpoints of light, and now you’re flying close,” Spilker says. “And you see the cliffs of Miranda”—a bizarre Uranian moon—“and Triton, with active geysers going off.” (Nobody had expected to see an active icy world in orbit around Neptune, and even now Voyager’s 35-year-old image is still the best we have of that strange little moon.)

When the Voyagers left the realm of the known planets, each followed a different path into darkness: Voyager 1 arced up and out of the plane of the solar system, and Voyager 2 looped downward. Spilker also followed her own path: she went to graduate school and earned her doctorate in planetary science using Voyager data—not knowing that several decades later, after leading NASA’s Cassini mission to Saturn, she’d again be part of the mission that started it all.

“The chance came to go back to Voyager,” she says. “And I said, ‘Of course. I’d love to go back.’”

In the interim, as the Voyagers sailed farther from their Earthly harbor, teams shut down many of the onboard instruments, including the cameras. But the pair kept studying the space that they alone were visiting. Their main job was now to characterize the heliosphere—the solar-system-encompassing, cosmic-ray-blocking bubble formed by our sun’s wind and magnetic field. They would document the alien mix of particles and fields that pervade near nothingness. And maybe, if they got lucky, the twins would each escape the protective solar caul entirely to be reborn as true interstellar wanderers.

In 2012 Voyager 1 transcended this boundary , known as the heliopause, where the sun’s influence wanes. Before that scientists could only guess at what lay beyond this barrier and could only model how it shielded Earth from the harshness of the void. Now Voyager 1 could tell us directly about the stuff between the stars. Voyager 2 followed in 2018 , and Fox—then the new chief of NASA’s heliophysics division—was in the midst of the action.

“You’re looking at the cosmic rays going up and the solar wind going down, and it was one of those ‘oh, my god, this is so exciting’ moments,” Fox recalls. “I think of the Voyagers as one mission,” she says. “We’re putting all the data together, but they’re the ones that are out there. They’re the brave spacecraft that have left the protective bubble of the heliosphere and are out exploring interstellar space. It’s hard not to be excited by them.”

This wasn’t the first time Voyager 1 had started speaking an unintelligible language. In 2022, when the probe suffered an earlier bout of garbled telemetry, JPL engineer Bob Rasmussen was shaken out of retirement. The lab wanted to know if Rasmussen, who’d joined the spacecraft’s systems engineering team in 1975, was willing to have a think about the situation.

“I’d been happily retired for a bit more than a year at that point, with plenty else to keep me busy,” Rasmussen says. “But I like solving puzzles, and this was a tough one that I just couldn’t pass up. Cracking it took a few months, but the puzzle stream hasn’t slowed since then.”

Afterward, he stayed on-call. So last November, when Voyager 1 again started transmitting nonsense, Rasmussen was ready for more problem-solving. He was joined by a hand-picked team of specialists, and together they dove into the details for getting the ailing spacecraft back in action.

The problems were at least three layers deep. First, it takes a long time to communicate with Voyager 1. Traveling at the speed of light, the radio signals used to command the spacecraft take 22.5 hours to travel 15 billion miles—and 22.5 hours to come back. Second, the Voyagers are not exactly modern technology.

“Most things don’t last 46 years. Your clock radio and toaster aren’t going to last 46 years,” says Dodd, who started on the Voyager project straight out of school, then worked on other missions and is now back on this one.

Plus, many of the people who built and developed the spacecraft in the 1970s aren’t around to explain the rationale behind the designs.

And third, unluckily enough, whatever had mangled the spacecraft had managed to take out Voyager 1’s ability to send meaningful communications. The team was in the dark, trying to find the invisible source of an error. (Imagine trying to revive a stalled desktop computer with a frozen screen: you can’t see your cursor, and your clicks risk causing more problems—except in this case each input carries a multiday lag and could damage a precious, misbehaving artifact that is more than 15 billion miles away.) Perhaps the most vexing part was the team’s knowledge that Voyager 1 was otherwise intact and functioning as it should be.

“It’s still doing what it’s supposed to be doing,” Westlake says. “It just can’t quite figure out how to send the correct message home.”

Rasmussen and his colleagues set out to understand the spacecraft in as much detail as possible. That meant poring over the original design schematics, now yellowed and pinned to various walls—an effort that resembled “a bit of an archaeology dig,” Dodd says—and studying how past teams had addressed anomalies. That was tricky, Dodd says, because even though the team members could figure out how engineers solved a problem, they couldn’t necessarily discern the rationale behind various solutions. They’d send commands to Voyager 1 about once a week—usually on Fridays—and by Sunday, they’d hear back from the spacecraft.

“There’s suspense after each cautious move, hope with each piece that falls into place, disappointment if our hunches are wrong,” Rasmussen says.

Progress was slow. And as time crept on, the team grew more concerned. But no one was giving up, at any level of leadership.

“I will rely on the Voyager team to say, ‘Hey, Nicky, we’ve done everything , ’” Fox says. “We wouldn’t make any decisions until we knew that every single thing had been tried and tried again because we really do want to get Voyager 1 back talking to us.”

And then, in early March, something changed. In response to a command, instead of beaming back absolute gibberish, the spacecraft sent a string of numbers that looked more familiar. It proved to be a Rosetta stone moment. Soon an unnamed engineer at NASA’s Deep Space Network—the globe-girdling array of radio dishes that relays information from Earth to spacecraft—had learned how to speak Voyager 1’s jumbled language.

After translating that vaguely familiar portion of the spacecraft’s transmission, the team could see that it contained a readout of the flight data system’s memory. Now they face new questions: Can they find and correct the source of the mutated code? Can they learn whether the spacecraft is sending useful science data? Can they restore Voyager 1’s lexicon to its original state—or will they need to continue speaking in the probe’s new postheliopause patois? “The hope is that we’ll get good science data back,” Westlake says. “Thinking about something that’s been a constant throughout my entire career going away is really tough to think about.”

But either by glitch or time’s slow decay of radioactive power sources, the Voyagers will, of course, eventually fade away. Each year they lose four watts of power, and they grow ever colder. “Whether it’s this particular anomaly that gets us or one downstream, or the spacecraft gets old enough and cold enough —one day you’ll go to look for it and it has just stopped working,” Spilker says.

Like silent ambassadors or wordless emissaries, the Voyagers will keep sailing outward, still carrying us with them into the stars—“sort of like a message a bottle,” Spilker says.

Besides their science payloads, a fraction of each spacecraft’s mass was devoted to casting a cosmic message into the interstellar ocean from a lonely island called Earth. Mounted to each probe is a golden record etched with grooves encoding a selection of sights and sounds from our small corner of space and time. An accompanying stylus is positioned to play the record from the beginning, alongside a pictographic and arithmetic instruction manual.

The records are gold because gold is stable for eons, and they’re records because that was the best way to store a lot of information in the 1970s. Should they ever be recovered and decoded, the message will tell the stories of we humans—at least as envisioned (and in some cases performed) by a small group of folks that included my parents ( the late astrophysicist Frank Drake and his surviving spouse Amahl Shakhashiri Drake), astronomer Carl Sagan, documentary producer Ann Druyan and science writer Timothy Ferris. Those stories are imperfect. They’re filled with lopsided optimism and scrubbed of references to war, famine, poverty and most any other Earthly failing—a deliberate decision to hide the defects of our broken world. I know this because my dad, the record’s technical director and a pioneer in the scientific quest to find cosmic civilizations, told me about the hard choices he’d made in selecting the photographs. And I know it because my mom, who recorded the message’s Arabic greeting (“Greetings to our friends in the stars. We wish that we will meet you someday”), helped, too.

For me, as the Voyagers travel through space , they’re not only helping us understand the cosmic context in which we exist; they’re also bearing a memento of my parents into the stars. These spacecraft—and their gleaming paean to Earth—will survive for billions of years. Long after our world, our sun and everything we hold dear becomes unrecognizable, the Voyagers will remain, resolutely speeding ever farther from a home that no longer exists and containing artifacts of a civilization that once was.

That’s why, over nearly half a century, the Voyagers and their interstellar tidings have come to be bigger than the already audacious mission they were designed to accomplish. Their reach is broader. And their inevitable silence will be profound.

“The thought that they’re out there on their own and you can no longer communicate with them—it’s traumatic,” Fox says. “It’s sad. It’s really sad.”

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Some hope —

Finally, engineers have a clue that could help them save voyager 1, a new signal from humanity's most distant spacecraft could be the key to restoring it..

Stephen Clark - Mar 15, 2024 11:23 pm UTC

It's been four months since NASA's Voyager 1 spacecraft sent an intelligible signal back to Earth, and the problem has puzzled engineers tasked with supervising the probe exploring interstellar space.

But there's a renewed optimism among the Voyager ground team based at NASA's Jet Propulsion Laboratory in California. On March 1, engineers sent a command up to Voyager 1—more than 15 billion miles (24 billion kilometers) away from Earth—to "gently prompt" one of the spacecraft's computers to try different sequences in its software package. This was the latest step in NASA's long-distance troubleshooting to try to isolate the cause of the problem preventing Voyager 1 from transmitting coherent telemetry data.

Cracking the case

Officials suspect a piece of corrupted memory inside the Flight Data Subsystem (FDS), one of three main computers on the spacecraft, is the most likely culprit for the interruption in normal communication. Because Voyager 1 is so far away, it takes about 45 hours for engineers on the ground to know how the spacecraft reacted to their commands—the one-way light travel time is about 22.5 hours.

The FDS collects science and engineering data from the spacecraft's sensors, then combines the information into a single data package, which goes through a separate component called the Telemetry Modulation Unit to beam it back to Earth through Voyager's high-gain antenna.

Engineers are almost entirely certain the problem is in the FDS computer. The communications systems onboard Voyager 1 appear to be functioning normally, and the spacecraft is sending a steady radio tone back to Earth, but there's no usable data contained in the signal. This means engineers know Voyager 1 is alive, but they have no insight into what part of the FDS memory is causing the problem.

But Voyager 1 responded to the March 1 troubleshooting command with something different from what engineers have seen since this issue first appeared on November 14.

"The new signal was still not in the format used by Voyager 1 when the FDS is working properly, so the team wasn’t initially sure what to make of it," NASA said in an update Wednesday. "But an engineer with the agency’s Deep Space Network, which operates the radio antennas that communicate with both Voyagers and other spacecraft traveling to the Moon and beyond, was able to decode the new signal and found that it contains a readout of the entire FDS memory."

Now, engineers are meticulously comparing each bit of code from the FDS memory readout to the memory readout Voyager 1 sent back to Earth before the issue arose in November. This, they hope, will allow them to find the root of the problem. But it will probably take weeks or months for the Voyager team to take the next step. They don't want to cause more harm.

"Using that information to devise a potential solution and attempt to put it into action will take time," NASA said.

This is perhaps the most serious ailment the spacecraft has encountered since its launch in 1977. Voyager 1 flew by Jupiter and Saturn before getting a kick from Saturn's gravity to speed into the outer solar system. In 2012, Voyager 1 entered interstellar space when it crossed the heliopause, where the solar wind, the stream of particles emanating from the Sun, push against a so-called galactic wind, the particles that populate the void between the stars.

Engineers have kept Voyager 1 and its twin, Voyager 2, alive for more than 46 years , overcoming technical problems that have doomed other space missions. Both probes face waning power from their nuclear batteries, and there are concerns about their thrusters aging and fuel lines becoming clogged, among other things. But each time there is a problem, ground teams have come up with a trick to keep the Voyagers going, often referencing binders of fraying blueprints and engineering documents from the spacecraft's design and construction nearly 50 years ago.

Suzanne Dodd, NASA's project manager for Voyager 1 and its twin, Voyager 2, recently told Ars that engineers would need to pull off their "biggest miracle" to restore Voyager 1 to normal operations. Now, Voyager 1's voice from the sky has provided engineers with a clue that could help them realize this miracle.

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The Voyager 1 spacecraft has a big glitch. Now, NASA must figure out how to fix it

Nell Greenfieldboyce

Regina G. Barber

Margaret Cirino

Geoff Brumfiel

This artist's concept shows the Voyager 1 spacecraft entering the space between stars. Interstellar space is dominated by plasma, ionized gas (illustrated here as brownish haze). NASA/JPL-Caltech hide caption

This artist's concept shows the Voyager 1 spacecraft entering the space between stars. Interstellar space is dominated by plasma, ionized gas (illustrated here as brownish haze).

The Voyager 1 space probe is the farthest human-made object in space. It launched in 1977 with a golden record on board that carried assorted sounds of our home planet: greetings in many different languages, dogs barking, and the sound of two people kissing, to name but a few examples. The idea with this record was that someday, Voyager 1 might be our emissary to alien life – an audible time capsule of Earth's beings. Since its launch, it also managed to complete missions to Jupiter and Saturn. In 2012, it crossed into interstellar space.

But a few months ago, the probe encountered a problem. "It's an elderly spacecraft," says NPR science correspondent Nell Greenfieldboyce , "and it had some kind of electronic stroke." Greenfieldboyce talks to Short Wave Host Regina G. Barber about the precarious status of Voyager 1 – the glitch threatening its mission, and the increasingly risky measures NASA is taking to try and restore it.

What interstellar adventure should we cover next? Email the show at [email protected] .

Listen to Short Wave on Spotify , Apple Podcasts and Google Podcasts .

Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave .

This episode was produced by Margaret Cirino and edited by Geoff Brumfiel. Gilly Moon was the audio engineer.

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NASA finds clue while solving Voyager 1's communication breakdown case

An outlier signal has brought ground control closer to decoding the troubling problem.

NASA engineers are a step closer to solving the communication problem that left the Voyager 1 spacecraft, which presently sits outside the solar system, unable to send usable data back to Earth.

In 2012, Voyager 1 became the first human-made object to leave the solar system and enter interstellar space . For 11 years following this achievement, the spacecraft dutifully sent data to ground control. This was data that detailed how space works beyond the influence of the sun. In Nov. 2023, however, Voyager 1's communications with ground operators stopped making sense. 

To be clear, however, Voyager 2 , which followed its spacecraft sibling out of the solar system in 2018, is still operational and communicating with Earth.

"Effectively, the call between the spacecraft and the Earth was still connected, but Voyager's 'voice' was replaced with a monotonous dial tone," Voyager 1's engineering team previously told Space.com .

The source of the issue appears to be one of Voyager 1's three onboard computers: The flight data subsystem (FDS). This computer, NASA says , is responsible for packaging science and engineering data before it's sent to Earth by the spacecraft's telemetry modulation unit.

Related: NASA's Voyager 1 glitch has scientists sad yet hopeful: 'Voyager 2 is still going strong'

The positive step towards solving communications issues between ground control and Voyager 1 came on March 3 when the Voyager mission team detected activity from one section of the FDS that was different from the rest of the computer’s garbled data stream.

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Voyager 1's messaging to Earth comes in the form of 1s and 0s, a computer language called binary code — but since the end of last year, this code has carried no meaning. Even the newly detected signal is still not in the correct format Voyager 1 should be using when FDS is functioning as designed, meaning the operating team was initially not quite sure what to make of it.

This changed, however, when an engineer at NASA's Deep Space Network , which is tasked with operating radio antennas that communicate with Voyager 1 and its interstellar sibling Voyager 2, as well as other NASA spacecraft closer to home, got a look at the code. The unnamed engineer was able to decode the outlier signal, discovering that it contained a readout of the FDS' entire memory.

Encoded with the FDS memory are performance instructions and code values that can change either if the spacecraft's status changes or if commanded to do so. Science and engineering data to be sent back to Earth are also locked up in the memory. 

The team will now compare this new signal, which occurred because of a prompt, or "poke," from mission control, to data that was sent back to Earth just before Voyager 1 started spouting binary nonsense. Finding discrepancies between regular Voyager 1 data and this poke-prompted signal will help the crew hunt for the source of the issue. The idea of the poke was to prompt FDS to try using different sequences in its software package and determine if the communication issue could be resolved by navigating around a corrupted or damaged section.

—  Voyager 2: An iconic spacecraft that's still exploring 45 years on

—  NASA's interstellar Voyager probes get software updates beamed from 12 billion miles away

—  NASA Voyager 2 spacecraft extends its interstellar science mission for 3 more years

Voyager 1 is currently around 15 billion miles (24 billion kilometers) from Earth, meaning that solving communication issues can be a painstaking process. It takes 22.5 hours to receive a radio signal from Voyager 1, then another 22.5 hours to receive a response via the Deep Space Network's antennas.

That means the results of NASA's poke were received on March 3, and on March 7 engineers started working to decode this signal. Three days later they determined the signal contains an FDS memory readout.

NASA scientists and engineers will continue to analyze this readout to restore communication with the pioneering space mission that extended humanity's reach beyond the solar system.

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: [email protected].

Robert Lea is a science journalist in the U.K. whose articles have been published in Physics World, New Scientist, Astronomy Magazine, All About Space, Newsweek and ZME Science. He also writes about science communication for Elsevier and the European Journal of Physics. Rob holds a bachelor of science degree in physics and astronomy from the U.K.’s Open University. Follow him on Twitter @sciencef1rst.

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Voyager 1 is 15 billion miles from home and broken. Here's how NASA is trying to fix it.

A scrambled computer signal may be the key that helps NASA engineers resume data transmission from the distant Voyager 1, a spacecraft that was launched in 1977 and now, 15 billion miles from home, is the farthest a human-made object has traveled from Earth.

Voyager 1 – and its sister craft, Voyager 2 – are robotic space probes that became the first spacecraft to leave our solar system and plunge into interstellar space, 11 billion miles from the sun.

They were designed to last five years , but have become the longest-operating spacecraft in history. Both carry gold-plated copper discs containing sounds and images from Earth, contents that were chosen by a team headed by celebrity astronomer Carl Sagan .

Voyager 2, now 12.7 billion miles from Earth, is functioning normally. However, a computer problem aboard Voyager 1 on Nov. 14, 2023, corrupted the stream of science and engineering data the craft is sending to Earth, making it unreadable , arstechnica.com reported.

Voyager 1 can receive communications from Earth. It is still transmitting, but its returning signals have been replaced “with a monotonous dial tone ,” according to space.com.

Unable to see our graphics? Click here to see them .

What's the problem with Voyager 1?

NASA and Jet Propulsion Laboratory engineers traced the problem to one of Voyager’s three onboard computers, one called a Flight Data System. The system collects information, including:

◾ Data from science instruments that monitor cosmic rays, solar wind particles, the sun's magnetic field, and other phenomena.

◾ Engineering data on spacecraft operating systems.

The Flight Data System gives that information to the spacecraft’s Telemetry Modulation Unit. The The unit converts the data to binary code – consisting of zeros and ones, the simplest form of computer code – then transmits that code to Earth, using Voyager's 12-foot antenna dish.

The data is received by NASA's Deep Space Network , giant 112-foot radio antennas placed around the world. The network handles space communications from several missions.

In November, the Telemetry Modulation Unit transmissions became a repeating pattern of zeros and ones " as if it were stuck ," NASA said.

Engineers restarted the Flight Data System in December, but that failed to fix the problem.

Voyager 1 is far away – and it's getting old

Voyager 1 has been in space for more than 46 years. Attempts to fix problems aboard the spacecraft often mean "consulting original, decades-old documents written by engineers who didn’t anticipate the issues that are arising today," NASA says. 

Engineers have consulted archived documents to find solutions to other Voyager problems in the past, wired.com says.

Engineers need time to understand how new commands will affect the spacecraft and to avoid unintended consequences. It's a complicated, time-consuming process.

A long time lag makes solving the problem more difficult. Voyager is moving at about 38,000 mph. It takes 22.5 hours for an Earth radio signal to reach Voyager and another 22.5 hours for the spacecraft’s reply to reach antenna networks on Earth.

That means engineers must wait 45 hours to get a response and learn if a command has been successful.

What was the key computer signal?

The key signal was received after engineers "poked" the spacecraft.

◾ March 1: Teams send a command known as a “poke” to Voyager. In essence, the poke tells the Flight Data System to try different sequences in its software program, in the hope a corrupted portion can be found and bypassed.

◾ March 3: Engineers receive a new signal from Voyager that is different from both the unreadable dial tone and the spacecraft’s original transmission stream.

◾ March 7: Engineers begin decoding the signal.

◾ March 10: A Deep Space Network engineer finishes decoding the new signal and finds it contains a readout of the spacecraft’s entire Flight Data System memory. That includes instructions for the spacecraft when it receives commands or when its operational status changes. 

The memory also contains science or engineering data for downlink, NASA says.

What happens next?

Engineers will compare the readout to those transmitted before the problem started. They hope to find differences that will help diagnose the problem.

Voyager 2 was launched first on Aug. 20, 1977. Voyager 1 was launched Sept. 5, 1977. It was put on a faster, shorter trajectory, which took it to interstellar space ahead of Voyager 2.

The Voyagers are the only spacecraft in the interstellar void. NASA's New Horizons probe , launched Jan. 19, 2006, flew past Pluto in 2015 and is expected to enter interstellar space in the 2040s.

NASA engineers have renewed hope to fix hobbled Voyager 1 after interstellar space data outage

The process of troubleshooting an issue with voyager 1 traveling through interstellar space is complicated. it takes about 45 hours for commands to be sent and a response to come back, but nasa engineers recently got a new clue to solving the spacecraft computer issue..

Discovering Uranus

FILE VIDEO: Uranus was discovered 241 years ago.

NASA engineers are acting as detectives to resolve a communication issue with the Voyager 1 spacecraft, one of the space agency's 46-year-old twin spacecraft zooming through interstellar space.

Voyager 1 and 2 launched in 1977 a few weeks apart, taking advantage of a 176-year planetary alignment to take a grand tour of all four giant outer planets – Neptune , Uranus , Saturn and Jupiter . The spacecraft missions have continued decades after those final planet flybys, eventually entering interstellar space.

Voyager 1 is more than 15.1 billion miles from Earth, and in mid-November, the spacecraft began sending back nonsense computer code instead of science data.

VOYAGER 1 AND 2 CONTINUE OFFERING NEW MYSTERIES FROM INTERSTELLAR SPACE

"It looked like it was just sending back what was the equivalent of just a single tone, you could think about, like a dial tone," Voyager Program scientist Linda Spilker said. "It had gone from sending back useful information, all those ones and zeros turning into data, to now just sort of being stuck sort of in a repetitive loop of ones and zeros and no longer basically communicating with us."

NASA engineers have honed in on one of three computers on the spacecraft, known as the Flight Data System (FDS), as the cause behind the communication problem. The FDS is returning unusable data from the telemetry modulation unit (TMU). 

" Its role is to basically collect all of the data from the science instruments and the spacecraft, package them all neatly up and send them back to the Earth," Spilker said of the FDS.

Artist rendering of the Voyager 1 spacecraft

These two systems work in tandem to get science and engineering data back to Earth from 15 billion miles away.  

Troubleshooting an issue with a spacecraft traveling through interstellar space is complicated. It takes about 22.5 hours for a message from Earth to reach the spacecraft and another 22.5 hours for a response back to Earth. The Voyagers were also constructed before the digital age.

Spilker said this combination makes the problem-solving effort multifaceted. Circuit diagrams for the FDS computer are posted in a room at JPL covered with sticky notes as engineers search through paper notes and contact retired Voyager engineers.

NASA REESTABLISHES CONTACT WITH VOYAGER 2 LOCATED MORE THAN 12 BILLION MILES FROM EARTH  

About once a week, Spilker said a team of engineers "sit down and think about what we can try next." After carefully creating and checking the plan, a command or a "poke" is sent to Voyager in hopes of fixing the corrupted section of the computer. Then, they wait two days to find out if it worked.

"The waiting in between is hard. That's for sure," Spilker said.

Archival image showing an engineer on the Voyager team working on the construction of the dish-shaped Voyager antenna. July 9, 1976.

(NASA/JPL-Caltech, NASA/JPL-Caltech Photojournal / NASA)

On Wednesday, NASA shared hopeful news that the Voyager team saw different activity on one section of the FDS but still not in the correct format. However, an engineer with NASA's Deep Space Network – a network of radio antennas to communicate with Voyagers and other spacecraft – was able to decode the signal and discovered a readout of the entire FDS memory.

This could be the breadcrumb Voyager's engineering team needs to get the spacecraft to speak the correct language again.

"The FDS memory includes its code, or instructions for what to do, as well as variables, or values used in the code that can change based on commands or the spacecraft’s status. It also contains science or engineering data for downlink," NASA's Jet Propulsion Laboratory wrote in a blog post . "The team will compare this readout to the one that came down before the issue arose and look for discrepancies in the code and the variables to potentially find the source of the ongoing issue."

This isn’t the first scare for either spacecraft. Another issue with garbled data for Voyager 1 in 2022 was fixed over several months. In 1981, the team experienced a similar communication issue to the current problem.

This illustration shows the positions of NASA’s Voyager 1 and Voyager 2 probes outside the heliosphere, the region surrounding our star, beyond which interstellar space begins. (Credit: NASA/JPL-Caltech)

Last year, an incorrect command sent Voyager 2 pointing away from Earth , unable to send back data. Teams were able to send a patch and reorient the spacecraft. 

Spilker and the rest of the Voyager team are used to bumps on this long road. However, it's worth it because the twin interstellar explorers are still collecting valuable data. 

Voyager 1 crossed the heliopause 11 years ago, and what it continues to send back is reshaping what scientists know about the interstellar medium. Eventually, future spacecraft missions traveling even farther from the Sun's influence will benefit from lessons learned from the Voyager missions. 

"It's just really an amazing story to think that two spacecraft are still operating after 46 years and having basically flown through the outer solar system … the entire heliosphere, across the heliopause, now on out into interstellar space," Spilker said. 

With the latest clue in this case, Voyager engineers are devising their next plan of action to help the spacecraft start sending back data from 15 billion miles from Earth.