what data does voyager send back

NASA has solved the mystery of Voyager 1's strange data transmissions

As NASA wrestles with Artemis 1's engine woes  that are delaying the return to human exploration of the moon, the agency has solved another mystery, one causing its 45-year-old spacecraft, Voyager 1, to transmit garbled data.   

NASA engineers have found the bug that was causing critical instruments on the four-decade-old spacecraft to send "garbled" health information to mission controllers on Earth.     

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Voyager 1's attitude articulation and control system (AACS), which keeps its antenna directed at Earth, earlier this year started to send back information that didn't reflect what was actually happening onboard . The AACS appeared to be functioning normally, but the data it was sending back was deemed invalid because it didn't match any possible state the system could be in. 

SEE: What is Artemis? Everything you need to know about NASA's new moon mission

Also, the rest of the probe appeared healthy, since it continued to gather and return science data.  

The agency today said it has found the source of the garbled information: a zombie computer that should not have been used to relay telemetry data. 

"The AACS had started sending the telemetry data through an onboard computer known to have stopped working years ago, and the computer corrupted the information," NASA said in a press release .  

While NASA engineers have solved the problem, they still don't know why the AACS started routing information through the non-functioning computer. However, they guess that the AACS probably received a faulty command from another onboard computer. 

NASA notes that if that other onboard computer generated a bad command, there could be an issue somewhere else on the spacecraft. The search continues for what the underlying issue is, but engineers believe it won't drastically harm its future. 

SEE:  NASA's new tiny, high-powered laser could find water on the Moon

"We're happy to have the telemetry back," said Suzanne Dodd, Voyager's project manager. 

"We'll do a full memory readout of the AACS and look at everything it's been doing. That will help us try to diagnose the problem that caused the telemetry issue in the first place. So we're cautiously optimistic, but we still have more investigating to do." 

Voyager 1 launched from Cape Canaveral in September 1977 and is now the farthest spacecraft from Earth, traveling in space at about 14.5 billion miles (23.3 billion kilometers) away. It would take light about 20 hours to travel from the spacecraft. 

The Voyager 1 was the first human-made object to reach into interstellar space and in 1998 overtook NASA's Pioneer 10 to become the most distant human-made object. 

It reached interstellar space in August 2012 and, among other things, takes measurements of the density of material in interstellar space . It will eventually exit the solar system but not for a long, long time.

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Voyager 1 Sends Clear Data to NASA for the First Time in Five Months

The farthest spacecraft from Earth had been transmitting nonsense since November, but after an engineering tweak, it finally beamed back a report on its health and status

Will Sullivan

Daily Correspondent

For the first time in five months, NASA has received usable data from Voyager 1, the farthest spacecraft from Earth.

The aging probe, which has traveled more than 15 billion miles into space, stopped transmitting science and engineering data on November 14. Instead, it sent NASA a nonsensical stream of repetitive binary code . For months, the agency’s engineers undertook a slow process of trial and error, giving the spacecraft various commands and waiting to see how it responded. Thanks to some creative thinking, the team identified a broken chip on the spacecraft and relocated some of the code that was stored there, according to the agency .

NASA is now receiving data about the health and status of Voyager 1’s engineering systems. The next step is to get the spacecraft to start sending science data again.

“Today was a great day for Voyager 1,” Linda Spilker , a Voyager project scientist at NASA’s Jet Propulsion Laboratory (JPL), said in a statement over the weekend, per CNN ’s Ashley Strickland. “We’re back in communication with the spacecraft. And we look forward to getting science data back.”

Hi, it's me. - V1 https://t.co/jgGFBfxIOe — NASA Voyager (@NASAVoyager) April 22, 2024

Voyager 1 and its companion, Voyager 2, separately launched from Earth in 1977. Between the two of them, the probes have studied all four giant planets in the outer solar system—Jupiter, Saturn, Uranus and Neptune—along with 48 of their moons and the planets’ magnetic fields. The spacecraft observed Saturn’s rings in detail and discovered active volcanoes on Jupiter’s moon Io .

Originally designed for a five-year mission within our solar system, both probes are still operational and chugging along through space, far beyond Pluto’s orbit. In 2012, Voyager 1 became the first human-made object to reach interstellar space, the area between stars. The probe is now about eight times farther from the sun than Uranus is on average.

Over the decades, the Voyager spacecraft have transmitted data collected on their travels back to NASA scientists. But in November, Voyager 1 started sending gibberish .

Engineers determined Voyager 1’s issue was with one of three onboard computers, called the flight data system (FDS), NASA said in a December blog post . While the spacecraft was still receiving and executing commands from Earth, the FDS was not communicating properly with a subsystem called the telemetry modulation unit (TMU). The FDS collects science and engineering data and combines it into a package that the TMU transmits back to Earth.

Since Voyager 1 is so far away, testing solutions to its technical issues requires time—it takes 22.5 hours for commands to reach the probe and another 22.5 hours for Voyager 1’s response to come back.

On March 1, engineers sent a command that coaxed Voyager 1 into sending a readout of the FDS memory, NASA said in a March 13 blog post . From that readout, the team confirmed a small part—about 3 percent—of the system’s memory had been corrupted, NASA said in an April 4 update .

The core of the problem turned out to be a faulty chip hosting some software code and part of the FDS memory. NASA doesn’t know what caused the chip to stop working—it could be that a high-energy particle from space collided with it, or the chip might have just run out of steam after almost 50 years spent hurtling through the cosmos.

“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,” Suzanne Dodd , Voyager project manager at JPL, told Scientific American ’s Nadia Drake in March.

To receive usable data again, the engineers needed to move the affected code somewhere else that wasn’t broken. But no single location in the FDS memory was large enough to hold all of the code, so the engineers divided it into chunks and stored it in multiple places, per NASA .

The team started with moving the code responsible for sending Voyager’s status reports, sending it to its new location in the FDS memory on April 18. They received confirmation that the strategy worked on April 20, when the first data on the spacecraft’s health since November arrived on Earth.

In the next several weeks, the team will relocate the parts of the FDS software that can start returning science data.

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Will Sullivan | | READ MORE

Will Sullivan is a science writer based in Washington, D.C. His work has appeared in Inside Science and NOVA Next .

Engineers Investigating NASA’s Voyager 1 Telemetry Data

NASA’s Voyager 1 spacecraft, shown in this illustration, has been exploring our solar system since 1977, along with its twin, Voyager 2.

While the spacecraft continues to return science data and otherwise operate as normal, the mission team is searching for the source of a system data issue.

The engineering team with NASA’s Voyager 1 spacecraft is trying to solve a mystery: The interstellar explorer is operating normally, receiving and executing commands from Earth, along with gathering and returning science data. But readouts from the probe’s attitude articulation and control system (AACS) don’t reflect what’s actually happening onboard.

The AACS controls the 45-year-old spacecraft’s orientation. Among other tasks, it keeps Voyager 1’s high-gain antenna pointed precisely at Earth, enabling it to send data home. All signs suggest the AACS is still working, but the telemetry data it’s returning is invalid. For instance, the data may appear to be randomly generated, or does not reflect any possible state the AACS could be in.

The issue hasn’t triggered any onboard fault protection systems, which are designed to put the spacecraft into “safe mode” – a state where only essential operations are carried out, giving engineers time to diagnose an issue. Voyager 1’s signal hasn’t weakened, either, which suggests the high-gain antenna remains in its prescribed orientation with Earth.

Get the Latest JPL News

The team will continue to monitor the signal closely as they continue to determine whether the invalid data is coming directly from the AACS or another system involved in producing and sending telemetry data. Until the nature of the issue is better understood, the team cannot anticipate whether this might affect how long the spacecraft can collect and transmit science data.

Voyager 1 is currently 14.5 billion miles (23.3 billion kilometers) from Earth, and it takes light 20 hours and 33 minutes to travel that difference. That means it takes roughly two days to send a message to Voyager 1 and get a response – a delay the mission team is well accustomed to.

“A mystery like this is sort of par for the course at this stage of the Voyager mission,” said Suzanne Dodd, project manager for Voyager 1 and 2 at NASA’s Jet Propulsion Laboratory in Southern California. “The spacecraft are both almost 45 years old, which is far beyond what the mission planners anticipated. We’re also in interstellar space – a high-radiation environment that no spacecraft have flown in before. So there are some big challenges for the engineering team. But I think if there’s a way to solve this issue with the AACS, our team will find it.”

It’s possible the team may not find the source of the anomaly and will instead adapt to it, Dodd said. If they do find the source, they may be able to solve the issue through software changes or potentially by using one of the spacecraft’s redundant hardware systems.

It wouldn’t be the first time the Voyager team has relied on backup hardware: In 2017, Voyager 1’s primary thrusters showed signs of degradation, so engineers switched to another set of thrusters that had originally been used during the spacecraft’s planetary encounters . Those thrusters worked, despite having been unused for 37 years.

Voyager 1’s twin, Voyager 2 (currently 12.1 billion miles, or 19.5 billion kilometers, from Earth), continues to operate normally.

Launched in 1977, both Voyagers have operated far longer than mission planners expected, and are the only spacecraft to collect data in interstellar space. The information they provide from this region has helped drive a deeper understanding of the heliosphere, the diffuse barrier the Sun creates around the planets in our solar system.

Each spacecraft produces about 4 fewer watts of electrical power a year, limiting the number of systems the craft can run. The mission engineering team has switched off various subsystems and heaters in order to reserve power for science instruments and critical systems. No science instruments have been turned off yet as a result of the diminishing power, and the Voyager team is working to keep the two spacecraft operating and returning unique science beyond 2025.

While the engineers continue to work at solving the mystery that Voyager 1 has presented them, the mission’s scientists will continue to make the most of the data coming down from the spacecraft’s unique vantage point.

More About the Mission

The Voyager spacecraft were built by JPL, 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://www.nasa.gov/voyager

News Media Contact

Calla Cofield

Jet Propulsion Laboratory, Pasadena, Calif.

626-808-2469

[email protected]

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How NASA Repaired Voyager 1 From 15 Billion Miles Away

Engineers have partially restored a 1970s-era computer on NASA's Voyager 1 spacecraft after five months of long-distance troubleshooting , building confidence that humanity's first interstellar probe can eventually resume normal operations.

Several dozen scientists and engineers gathered Saturday in a conference room at NASA's Jet Propulsion Laboratory, or connected virtually, to wait for a new signal from Voyager 1. The ground team sent a command up to Voyager 1 on Thursday to recode part of the memory of the spacecraft's Flight Data Subsystem (FDS) , one of the probe's three computers.

“In the minutes leading up to when we were going to see a signal, you could have heard a pin drop in the room,” said Linda Spilker, project scientist for NASA's two Voyager spacecraft at JPL. “It was quiet. People were looking very serious. They were looking at their computer screens. Each of the subsystem (engineers) had pages up that they were looking at, to watch as they would be populated.”

Finally, a Breakthrough

Launched nearly 47 years ago, Voyager 1 is flying on an outbound trajectory more than 15 billion miles (24 billion kilometers) from Earth, and it takes 22.5 hours for a radio signal to cover that distance at the speed of light. This means it takes nearly two days for engineers to uplink a command to Voyager 1 and get a response.

In November, Voyager 1 suddenly stopped transmitting its usual stream of data containing information about the spacecraft's health and measurements from its scientific instruments. Instead, the spacecraft's datastream was entirely unintelligible. Because the telemetry was unreadable, experts on the ground could not easily tell what went wrong. They hypothesized the source of the problem might be in the memory bank of the FDS.

There was a breakthrough last month when engineers sent up a novel command to “poke” Voyager 1's FDS to send back a readout of its memory. This readout allowed engineers to pinpoint the location of the problem in the FDS memory . The FDS is responsible for packaging engineering and scientific data for transmission to Earth.

After a few weeks, NASA was ready to uplink a solution to get the FDS to resume packing engineering data. This datastream includes information on the status of the spacecraft—things like power levels and temperature measurements. This command went up to Voyager 1 through one of NASA's large Deep Space Network antennae on Thursday.

Then, the wait for a response. Spilker, who started working on Voyager right out of college in 1977, was in the room when Voyager 1's signal reached Earth on Saturday.

“When the time came to get the signal, we could clearly see all of a sudden, boom, we had data, and there were tears and smiles and high fives,” she told Ars. “Everyone was very happy and very excited to see that, hey, we're back in communication again with Voyager 1. We're going to see the status of the spacecraft, the health of the spacecraft, for the first time in five months.”

Throughout the five months of troubleshooting, Voyager's ground team continued to receive signals indicating the spacecraft was still alive. But until Saturday, they lacked insight into specific details about the status of Voyager 1.

“It’s pretty much just the way we left it,” Spilker said. “We're still in the initial phases of analyzing all of the channels and looking at their trends. Some of the temperatures went down a little bit with this period of time that's gone on, but we're pretty much seeing everything we had hoped for. And that's always good news.”

Relocating Code

Through their investigation, Voyager's ground team discovered that a single chip responsible for storing a portion of the FDS memory had stopped working, probably due to either a cosmic ray hit or a failure of aging hardware. This affected some of the computer's software code.

“That took out a section of memory,” Spilker said. “What they have to do is relocate that code into a different portion of the memory, and then make sure that anything that uses those codes, those subroutines, know to go to the new location of memory, for access and to run it.”

Only about 3 percent of the FDS memory was corrupted by the bad chip, so engineers needed to transplant that code into another part of the memory bank. But no single location is large enough to hold the section of code in its entirety, NASA said.

So the Voyager team divided the code into sections for storage in different places in the FDS. This wasn't just a copy-and-paste job. Engineers needed to modify some of the code to make sure it will all work together. “Any references to the location of that code in other parts of the FDS memory needed to be updated as well,” NASA said in a statement.

Newer NASA missions have hardware and software simulators on the ground, where engineers can test new procedures to make sure they do no harm when they uplink commands to the real spacecraft. Due to its age, Voyager doesn't have any ground simulators, and much of the mission's original design documentation remains in paper form and hasn't been digitized.

“It was really eyes-only to look at the code,” Spilker said. “So we had to triple check. Everybody was looking through and making sure we had all of the links coming together.”

This was just the first step in restoring Voyager 1 to full functionality. “We were pretty sure it would work, but until it actually happened, we didn't know 100 percent for sure,” Spilker said.

“The reason we didn’t do everything in one step is that there was a very limited amount of memory we could find quickly, so we prioritized one data mode (the engineering data mode), and relocated only the code to restore that mode,” said Jeff Mellstrom, a JPL engineer who leads the Voyager 1 “tiger team” tasked with overcoming this problem.

“The next step, to relocate the remaining three actively used science data modes, is essentially the same,” Mellstrom said in a written response to Ars. “The main difference is the available memory constraint is now even tighter. We have ideas where we could relocate the code, but we haven’t yet fully assessed the options or made a decision. These are the first steps we will start this week.”

It could take “a few weeks” to go through the sections of code responsible for packaging Voyager 1's science data in the FDS, Spilker said.

That will be the key payoff, Spilker said. Voyager 1 and its twin spacecraft, Voyager 2, are the only operating probes flying in the interstellar medium, the diffuse gas between the stars. Their prime missions are long over. Voyager 1 flew by Jupiter and Saturn in 1979 and 1980, then got a gravitational boost toward the outer edge of the Solar System. Voyager 2 took a slower trajectory and encountered Jupiter, Saturn, Uranus, and Neptune.

For the past couple of decades, NASA has devoted Voyager's instruments to studying cosmic rays, the magnetic field, and the plasma environment in interstellar space. They're not taking pictures anymore. Both probes have traveled beyond the heliopause, where the flow of particles emanating from the Sun runs into the interstellar medium.

But any scientific data collected by Voyager 1 since November 14 has been lost. The spacecraft does not have the ability to store science data onboard. Voyager 2 has remained operational during the outage of Voyager 1.

Scientists are eager to get their hands on Voyager 1's science data again. “With the results we got on Saturday, we have new confidence that we can put together the pieces we need to now get back the science data,” Spilker said.

“One thing I'm particularly excited about—there's this feature in the Voyager 1 data. We nicknamed it Pressure Front 2,” Spilker said. “Pressure Front 2 is a jump in both the density of the plasma around the spacecraft and the magnetic field. It's lasted for three-and-a-half years.”

“We'd like to see, is this still there?” she continued. “It's different from what we've seen in the past, and we're trying to figure out, is it some influence coming from the Sun, or is it actually something coming from interstellar space that's creating this feature? So we'd like to see it again, get more data, and be able to study it more carefully.”

This story originally appeared on Ars Technica .

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April 22, 2024

After Months of Gibberish, Voyager 1 Is Communicating Well Again

NASA scientists spent months coaxing the 46-year-old Voyager 1 spacecraft back into healthy communication

By Meghan Bartels

NASA’s Voyager 1 spacecraft is depicted in this artist’s concept traveling through interstellar space, or the space between stars, which it entered in 2012.

NASA/JPL-Caltech

After months of nonsensical transmissions from humanity’s most distant emissary, NASA’s iconic Voyager 1 spacecraft is finally communicating intelligibly with Earth again.

Voyager 1 launched in 1977 , zipped past Jupiter and Saturn within just a few years and has been trekking farther from our sun ever since; the craft crossed into interstellar space in 2012. But in mid-November 2023 Voyager 1’s data transmissions became garbled , sending NASA engineers on a slow quest to troubleshoot the distant spacecraft. Finally, that work has paid off, and NASA has clear information on the probe’s health and status, the agency announced on April 22.

“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,” said Suzanne Dodd, Voyager project manager at NASA’s Jet Propulsion Laboratory in an interview with Scientific American when the team was still tracking down the issue.

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The Voyager 1 spacecraft is a scientific legend : It discovered that Jupiter’s moon Io, far from being a dead world like our own companion, is instead a supervolcanic world . The craft’s data suggested that Saturn’s moon Titan might have liquid on its surface. And for more than a decade, Voyager 1 has given scientists a glimpse at what space looks like beyond the influence of our sun.

Yet its long years in the harsh environment of space have done a number on the probe, which was designed to last just four years. In particular, degraded performance and low power supplies have forced NASA to turn off six of its 10 instruments, and its communication has gotten even spottier than can be explained by the fact that cosmic mechanics mean a signal takes nearly one Earth day to travel between humans and the probe.

When the latest communications glitch occurred last fall, scientists could still send signals to the distant probe, and they could tell that the spacecraft was operating. But all they got from Voyager 1 was gibberish—what NASA described in December 2023 as “a repeating pattern of ones and zeros.” The team was able to trace the issue back to a part of the spacecraft’s computer system called the flight data subsystem, or FDS, and identified that a particular chip within that system had failed.

Mission personnel couldn’t repair the chip. They were, however, able to break the code held on the failed chip into pieces they could tuck into spare corners of the FDS’s memory, according to NASA. The first such fix was transmitted to Voyager 1 on April 18. With a total distance of 30 billion miles to cross from Earth to the spacecraft and back, the team had to wait nearly two full days for a response from the probe. But on April 20 NASA got confirmation that the initial fix worked. Additional commands to rewrite the rest of the FDS system’s lost code are scheduled for the coming weeks, according to the space agency, including commands that will restore the spacecraft’s ability to send home science data.

Although, for now, Voyager 1 appears to be on the mend, NASA scientists know it won’t last forever. Sooner or later, a glitch they can’t fix will occur, or the spacecraft’s ever dwindling fuel supply will run out for good. Until then NASA is determined to get as much data as possible out of the venerable spacecraft—and its twin, Voyager 2, which experienced its own communications glitch earlier in 2023 .

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Voyager 2 sent back its first detailed data from interstellar space

By Leah Crane

4 November 2019

The two Voyager spacecraft have left the solar system

NASA/JPL-Caltech

Voyager 2 has sent back its first data from interstellar space. The spacecraft, launched in 1977 to study the outer planets of our solar system, passed Neptune in 1989 and then hurtled onwards to the edge of our solar system. It was declared to have exited the solar system in 2018, and has now sent back some of its first measurements from beyond.

The official edge of the solar system is called the heliopause. This is where particles blown out by the sun in the solar wind give way to the interstellar medium that permeates the entire galaxy. Voyager 2 is only the second spacecraft to have crossed the heliopause, after Voyager 1 left the solar system in 2012.

Now that researchers have analysed data from Voyager 2’s crossing, they have spotted a few differences between its measurements of the heliopause and the surrounding region and those from its predecessor. One is that Voyager 2’s crossing seemed to be smoother due to a thinner heliopause on its path.

Read more: We're hurtling into a new region of interstellar space. What now?

The probe also sent measurements from just beyond the heliopause. “Material from the solar bubble was leaking out into the galaxy at distances up to…170 million kilometres, and that was very different than what happened with Voyager 1, where barely any material was leaking out,” said Stamatios Krimigis at Johns Hopkins University in Maryland during a press conference. In fact, Voyager 1 actually saw material leaking into the galaxy from the interstellar medium.

One scientific instrument on Voyager 1 that measured the surrounding plasma – a form of matter in which a gas loses its electrons – was broken by the time the craft passed the heliopause, so Voyager 2 was able to look at some things that Voyager 1 could not. That included a layer inside the heliopause where the plasma seemed to pile up and get very dense, as well as a layer between the heliopause and interstellar space where the plasma from the two areas was mixed.

The heliopause remains largely mysterious despite the information from the Voyager missions: we don’t know its exact shape or structure, partially because both spacecraft left the solar system travelling in approximately the same direction. “Here’s an entire bubble that we’ve only crossed at two points,” said Krimigis. “Two examples are not enough.”

The spacecraft could still send back more data. Both are still functioning and taking measurements in interstellar space, but they will probably run out of power in the next five years or so. No further missions to interstellar space are currently planned.

Nature Astronomy DOI: 10.1038/s41550-019-0918-5

• solar system

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NASA's Voyager 1 is sending mysterious data from beyond our solar system. Scientists are unsure what it means.

• NASA said Voyager 1 is sending data that doesn't match the spacecraft's movements.
• The veteran spacecraft has been exploring our solar system and interstellar space since 1977.
• It is now 14.5 billion miles away from Earth, making it the most distant human-made object.

NASA's Voyager 1 is continuing its journey beyond our solar system, 45 years after it was launched. But now the veteran spacecraft is sending back strange data, puzzling its engineers.

NASA said on Wednesday that while the probe is still operating properly, readouts from its attitude articulation and control system — AACS for short — don't seem to match the spacecraft's movements and orientation, suggesting the craft is confused about its location in space. The AACS is essential for Voyager to send NASA data about its surrounding interstellar environment as it keeps the craft's antenna pointing right at our planet.

"A mystery like this is sort of par for the course at this stage of the Voyager mission," Suzanne Dodd, a project manager for Voyager 1 and 2 at NASA's Jet Propulsion Laboratory, said in a statement . "The spacecraft are both almost 45 years old, which is far beyond what the mission planners anticipated." NASA said Voyager 1's twin, the Voyager 2 probe, is behaving normally.

Launched in 1977 to explore the outer planets in our solar system, Voyager 1 has remained operational long past expectations and continues to send information about its journeys back to Earth. The trailblazing craft left our solar system and entered interstellar space in 2012 . It is now 14.5 billion miles away from Earth, making it the most distant human-made object.

NASA said that from what its engineers can tell, Voyager 1's AACS is sending randomly generated data that does not "reflect what's actually happening onboard." But even if system data suggests otherwise, the spacecraft's antenna seems to be properly aligned — it is receiving and executing commands from NASA and sending data back to Earth. It said that so far the system issue hasn't triggered the aging spacecraft to go into "safe mode," during which it carries out only essential operations.

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"Until the nature of the issue is better understood, the team cannot anticipate whether this might affect how long the spacecraft can collect and transmit science data," NASA said.

Dodd and her team hope to figure out what's prompting the robot emissary from Earth to send junky data. "There are some big challenges for the engineering team," Dodd said. A major one: It takes light 20 hours and 33 minutes to get to Voyager's current interstellar location, so a round-trip message between the space agency and Voyager takes two days.

"But I think if there's a way to solve this issue with the AACS, our team will find it," Dodd added.

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

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Voyager 1 and Voyager 2

Where are they now.

Both Voyager 1 and Voyager 2 have reached "interstellar space" and each continue their unique journey deeper into the cosmos. In NASA's Eyes on the Solar System app, you can see the actual spacecraft trajectories of the Voyagers updated every five minutes.

Mission Status

Instrument status.

Voyager 1 Present Position

Voyager 2 present position, discover more topics from nasa.

Voyager turns 45: What the iconic mission taught us and what's next

Can the first probe to visit Neptune and Uranus make it to its 50th anniversary?

Forty-five years ago, on Aug. 20, 1977, NASA's Voyager 2 spacecraft launched from Cape Canaveral, Florida, on a Titan III-Centaur rocket, embarking on a "grand tour" of the solar system that would include visits to the Jupiter and Saturn systems and would make it the first spacecraft to visit the ice giants Uranus and Neptune and their moons.  

Voyager 2 is now 12.1 billion miles (19.5 billion kilometers) away and still sending back data on the distant and unknown heliopause, and scientists are beginning to wonder how long the iconic space probe can keep going. 

Designed to take advantage of a once-every-176-years alignment in the 1970s that made it possible for spacecraft to take gravity-assist slingshots from planet to planet across the solar system , the Voyager mission consisted of two probes. Voyager 2 was the first to launch, with Voyager 1 following two weeks later. Both carried the famous " Golden Record ," a 12-inch gold-plated copper disc containing sounds and images portraying the diversity of life and culture on Earth . 

Now over 14.5 billion miles (23.3 billion km) away, Voyager 1 is the farthest artificial object from Earth. But Voyager 2 is arguably more iconic because of its incredible multidecade tour of the giant planets. 

Related: Celebrate 45 years of Voyager with these amazing images of our solar system (gallery)

Voyager's "grand tour"

Though it launched second, Voyager 1 was so called because it was to reach Jupiter and Saturn first — in March 1979 and November 1980, respectively — before exiting the plane of the planets where it took the famous "Pale Blue Dot" photo . Voyager 2 visited four planets: Jupiter in July 1979, Saturn in August 1981, Uranus in January 1986 and Neptune in August 1989. 

"Both Voyager 1 and Voyager 2 provided tremendous legacies for planetary exploration," Jonathan Lunine, a planetary scientist and physicist at Cornell University who is working on the Juno , Europa Clipper and James Webb Space Telescope missions, told Space.com. "Not only in what they accomplished in terms of science, but also demonstrating that it was really possible to explore the outer solar system with a couple of spacecraft."

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What did the Voyager probes reveal?

Voyager's discoveries are the stuff of legend among planetary scientists, many of whom still rely on the unique images from the spacecraft's wide-angle and narrow-angle cameras. The probes spotted volcanoes on Jupiter's moon Io , discovered that Jupiter's Great Red Spot is an Earth-size storm and found that the gas giant has faint rings. They studied Saturn's rings ; saw the giant moon Titan's thick, Earth-like atmosphere; and revealed the tiny moon Enceladus to be geologically active. 

Voyager 2 alone then visited Uranus and Neptune. The spacecraft's first-ever images of Uranus revealed dark rings, the planet's tilted magnetic field and its geologically active moon Miranda. Neptune, meanwhile, was also discovered to have rings and many more moons than scientists initially thought. We also got to see Triton , a geologically active moon that is orbiting "backward" and, like Pluto , is now believed to be a captured dwarf planet from the Kuiper Belt .  

Voyager as a catalyst 

In addition to making groundbreaking discoveries, the Voyager mission helped scientists determine what merited deeper exploration. The mission revealed Jupiter to be an incredibly complex planet, thus spurring NASA to launch the Galileo mission in 1989 and the Juno mission in 2011. The Voyager probes' work also helped to inspire the iconic Cassini mission to Saturn.

"Voyager 1's close flyby of Titan was the catalyst for the wonderful Cassini mission to Saturn and its Huygens probe," Lunine said. The Huygens probe landed on the surface of Titan in 2005 and sent back an incredible video . 

Voyager 2 has also been a catalyst for investigations into the role of the ice giant planets — not only in the solar system but also in distant star systems, since most of the exoplanets found so far are roughly the size of Neptune and Uranus. 

Voyager and NASA today 

NASA has spent decades following up on the Voyager missions, and those efforts continue today. The space agency's Dragonfly mission will reach Titan, Saturn's largest moon, in 2034, while Europa Clipper will study Jupiter's ocean moon, first imaged by Voyager, starting in 2030. In April, the National Academies Planetary Science Decadal Survey recommended that NASA send a $4.2 billion Uranus Orbiter and Probe mission to unveil the mysterious ice giant planet and its moons in the 2040s. 

It's the latest mission that's a direct consequence of Voyager 2's brief visit to the Uranus system in January 1986. "Voyager 2's flyby of Uranus was a bull's-eye — it went directly through the plane of the moons' orbits because of the orientation of Uranus' axis to the sun ," Lunine said. That made it unlike flybys at other planets, where the probes were able to visit one moon after another. "Voyager 2 got very brief images from these moons, so they're largely unexplored," Lunine said. 

Ariel and Miranda, in particular, are thought to be ocean worlds and so would be specifically targeted by the Uranus Orbiter and Probe. "It's been 45 years since the launch of Voyager 1 and Voyager 2, and here we are now finally talking about a Uranus Orbiter and Probe mission," Lunine said. "It seems like a long time because these missions take so long to conceive of, fund, build, launch and execute, but it all comes from the intriguing peeks that we got from Voyager 2." 

How long will Voyager last?

Both Voyager 1 and Voyager 2 still communicate with NASA's Deep Space Network (which itself was created to communicate with Voyager 2 at Uranus and Neptune), receiving routine commands and occasionally transmitting data to Earth. "We are still getting data from Voyager," Stamatios Krimigis, principal investigator for the Voyager 1 and 2 probes and the Voyager Interstellar Mission, said during a news conference held at COSPAR 22 in July. "We're looking forward to getting data for probably another five or six years."  

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Around the mid- to late 2020s , the probes' scientific instruments will be entirely switched off, and eventually, the spacecraft will go cold and silent — but their journeys into interstellar space will continue indefinitely. "My motto is, I want to be here after Voyager passes on," said Krimigis, who is in his 80s. "But I'm not sure that's going to happen."  

In around 300 years, Voyager 1 and 2 will enter the Oort cloud , the sphere of comets surrounding the solar system. About 30,000 years later, they'll exit the neighborhood and silently orbit the center of the Milky Way for millions of years. 

Their scientific work may be almost over, but the Voyager spacecraft have only just begun their journeys into the cosmos.

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Jamie is an experienced science, technology and travel journalist and stargazer who writes about exploring the night sky, solar and lunar eclipses, moon-gazing, astro-travel, astronomy and space exploration. He is the editor of  WhenIsTheNextEclipse.com  and author of  A Stargazing Program For Beginners , and is a senior contributor at Forbes. His special skill is turning tech-babble into plain English.

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