where is voyager 1 heading towards

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Where is Voyager 1 Headed and When Will It Get There?

Question:   The Voyager 1 spacecraft has left our solar system and is now in interstellar space but where exactly is it heading now and at its present speed how long will it take to get there.  — David

Answer:   I found the answer to this question on the Voyager FAQ page .  From the information on this page you can learn that Voyager 1 is escaping the solar system at a speed of about 3.5 Astronomical Units (AU: the average distance between the Earth and our Sun) per year along a direction that is 35 degrees out of the ecliptic plane to the north, in the general direction of the Sun’s motion motion relative to nearby stars. Voyager 1 in headed in the direction of the constellation Ophiuchus. In the year 40,272 AD, Voyager 1 will come within 1.7 light years of an obscure star in the constellation Ursa Minor called AC+79 3888.

Just for your information, Voyager 2 is also escaping the solar system at a speed of about 3.1 AU per year, 48 degrees out of the ecliptic plane to the south toward the constellations of Sagitarrius and Pavo. In about 40,000 years, Voyager 2 will come within about 1.7 light years of a star called Ross 248 the constellation of Andromeda.

Finally, if you want to see a very cool graphic which shows the trajectory of the Pioneer 10, Pioneer 11, Voyager 1, Voyager 2, and New Horizons spacecraft out of our solar system, check out the Spacecraft Escaping the Solar System page produced by the folks at Heavens Above .

Jeff Mangum

The Sun Spot

NASA Engineers Make Progress Toward Understanding Voyager 1 Issue

Since November 2023, NASA’s Voyager 1 spacecraft has been sending a steady radio signal to Earth, but the signal does not contain usable data. The source of the issue appears to be with one of three onboard computers, the flight data subsystem (FDS), which is responsible for packaging the science and engineering data before it’s sent to Earth by the telemetry modulation unit.

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. 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 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. 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 new signal resulted from a command sent to Voyager 1 on March 1. Called a “poke” by the team, the command is meant to gently prompt the FDS to try different sequences in its software package in case the issue could be resolved by going around a corrupted section.

Because Voyager 1 is more than 15 billion miles (24 billion kilometers) from Earth, it takes 22.5 hours for a radio signal to reach the spacecraft and another 22.5 hours for the probe’s response to reach antennas on the ground. So the team received the results of the command on March 3. On March 7, engineers began working to decode the data, and on March 10, they determined that it contains a memory readout.

The team is analyzing the readout. Using that information to devise a potential solution and attempt to put it into action will take time.

News Media Contact Calla  Cofield Jet Propulsion Laboratory, Pasadena, Calif. 626-808-2469 calla.e. cofield @jpl.nasa.gov

Interstellar Mission

Voyager 1 reached interstellar space in August 2012 and is the most distant human-made object in existence.

Mission Statistics

Launch Date

Sept. 5, 1977

About the mission

Voyager 1 reached interstellar space in August 2012 and is the most distant human-made object in existence. Launched just shortly after its twin spacecraft, Voyager 2, in 1977, Voyager 1 explored the Jovian and Saturnian systems discovering new moons, active volcanoes and a wealth of data about the outer solar system.

Voyagers 1 and 2 were designed to take advantage of a rare planetary alignment that occurs only once in 176 years and remain the most well traveled spacecraft in history. Both spacecraft carry a sort of time capsule called the Golden Record, a 12-inch gold-plated copper disk containing sounds and images selected to portray the story of our world to extraterrestrials.

Instruments

• Imaging system
• Infrared interferometer spectrometer
• Ultraviolet spectrometer
• Triaxial fluxgate magnetometer
• Plasma spectrometer
• Low-energy charged particles detectors
• Cosmic Ray System (CRS)
• Photopolarimeter System (PPS)
• Plasma Wave System (PWS)

Mission Highlights

Sept. 1, 2013

Interactive 3D model of Voyager 1. View the full interactive experience at Eyes on the Solar System .

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NASA's 40-year Voyage Continues

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Four decades ago, NASA launched two robotic spacecraft, Voyagers 1 and 2 , on a mission to cruise by the giant planets of the outer solar system on sweeping trajectories that would ultimately carry them far beyond.

Today, both spacecraft are still functioning, sending back data from the cold, dark reaches of the frontier of interstellar space. Voyager 2 is over 10.6 billion miles from the sun, 115 times farther than Earth. Voyager 1 is almost 13 billion miles out—a distance that takes radio signals, traveling at the speed of light, over 19 hours to traverse!

Voyager Mission Recap

The Voyagers were launched in 1977—Voyager 1 on September 5 and Voyager 2 on August 20, so their 40th anniversaries in space are close at hand.

Voyager 1’s objective was to explore Jupiter and Saturn, and gave us our first detailed images of Jupiter’s four large Galilean moons. It also made a close flyby of Saturn’s largest moon, Titan , giving us our first look at the moon’s cold, thick, hydrocarbon-smog-laced atmosphere.

Voyager 2 also passed by Jupiter and Saturn, before cruising onward to the cold and mysterious “ice giant” worlds Uranus and Neptune—which still have not been visited by any other spacecraft.

Pushing the Frontiers of Space

Upon completion of their primary missions, both Voyagers coasted onward to ever greater distances, having achieved escape velocity from the sun’s gravitation. And though they spent their earliest years of exploration traveling within the orbital plane of the solar system’s planets, the Voyagers’ final planetary encounters flung them in different directions. Voyager 1 is heading northward away from the plane of the solar system while Voyager 2 is going south.

Since leaving the realm of planets, the Voyagers have been monitoring the physical conditions within the heliosphere , the extended “bubble” of gas, plasma, and magnetic fields emanating from the sun and blowing outward into space, called the solar wind. The goal of this extended phase of the Voyagers’ mission was to find the boundary between the solar wind’s influence and the environment of interstellar space: the heliopause .

From Earth, we cannot detect that boundary—much in the way that you cannot “see” the boundary between Earth’s atmosphere and outer space by standing on the ground and looking up. To find where space beings, you must send up a rocket to measure the pressure and temperature of the air.

Voyager 1’s measurements of the solar wind tell us that in August 2012, it did in fact cross the heliopause and enter the frontier of interstellar space , becoming the first human artifact to do so.

Voyager 2 has not yet crossed the heliopause in the direction it is traveling, but when it does, researchers will receive data from two different points in the interstellar realm, which will offer a more detailed picture of the nature of space beyond the influence of the sun.

Built to Survive the Unknown

How have these robotic explorers lasted so long? What machinery in your experience can last forty years with no maintenance, refueling, or recharging?

The Voyagers had to last at least through their primary missions, which in Voyager 2’s case included encounters with four giant planets over a 10-year period. Engineers had to anticipate the harsh conditions their robots might encounter, and plan accordingly—even though the actual conditions around the target planets and in the vast stretches of space between them were largely unknown.

The Voyagers’ sensitive equipment and computer systems are heavily shielded against micrometeorite impacts and high-energy radiation. Critical systems were given multiple redundant backups, so that if a piece of equipment fails a backup duplicate will kick in to replace it.

As for their power supplies, the Voyagers are each equipped with three radioisotope thermoelectric generators , which generate electricity from heat produced by the decay of Plutonium-238. At the time of launch each trio of generators produced 470 Watts, though the output has declined steadily as the Plutonium decays. It is expected that by sometime between 2025 and 2030, power will have fallen below the level needed to run any of the Voyagers’ instruments.

Messengers for ET? Good idea?

Another ride-a-long feature on each Voyager is the “ Golden Record ,” a gold-plated analog phonograph record carrying information about our world and species in a set of selected sounds and images. The records are intended as combination time capsules and greeting cards, in the event that either spacecraft is recovered by an intelligent alien civilization who can follow the graphical instructions inscribed on the record covers and extract the information on the disks.

There are some who feel it may not be a good idea to randomly fling information of our existence and location into space for any would-be aliens to find–for how could we possibly know what those aliens are like, and what they would do with the information?

Still, the chances of recovery of the tiny, soon-to-be-derelict spacecraft in the vast expanse of interstellar space is exceedingly small, and neither are heading toward any star systems in the near or extended future. Voyager 1 is presently heading in the general direction of a star called Gliese 445, which it will pass within 1.6 light years of in about 40,000 years.

In the meantime, Voyagers 1 and 2 should continue to transmit home their measurements from the interstellar frontier, so may yet teach us a thing or two about our place in the cosmos.

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The Voyager missions

Highlights Voyager 1 and Voyager 2 launched in 1977 and made a grand tour of the solar system's outer planets. They are the only functioning spacecraft in interstellar space, and they are still sending back measurements of the interstellar medium. Each spacecraft carries a copy of the golden record, a missive from Earth to any alien lifeforms that may find the probes in the future.

What are the Voyager missions?

The Voyager program consists of two spacecraft: Voyager 1 and Voyager 2. Voyager 2 was actually launched first, in August 1977, but Voyager 1 was sent on a faster trajectory when it launched about two weeks later. They are the only two functioning spacecraft currently in interstellar space, beyond the environment controlled by the sun.

Voyager 2’s path took it past Jupiter in 1979, Saturn in 1981, Uranus in 1985, and Neptune in 1989. It is the only spacecraft to have visited Uranus or Neptune, and has provided much of the information that we use to characterize them now.

Because of its higher speed and more direct trajectory, Voyager 1 overtook Voyager 2 just a few months after they launched. It visited Jupiter in 1979 and Saturn in 1980. It overtook Pioneer 10 — the only other spacecraft in interstellar space thus far — in 1998 and is now the most distant artificial object from Earth.

How the Voyagers work

The two spacecraft are identical, each with a radio dish 3.7 meters (12 feet) across to transmit data back to Earth and a set of 16 thrusters to control their orientations and point their dishes toward Earth. The thrusters run on hydrazine fuel, but the electronic components of each spacecraft are powered by thermoelectric generators that run on plutonium. Each carries 11 scientific instruments, about half of which were designed just for observing planets and have now been shut off. The instruments that are now off include several cameras and spectrometers to examine the planets, as well as two radio-based experiments. Voyager 2 now has five functioning instruments: a magnetometer, a spectrometer designed to investigate plasmas, an instrument to measure low-energy charged particles and one for cosmic rays, and one that measures plasma waves. Voyager 1 only has four of those, as its plasma spectrometer is broken.

Jupiter findings

Over the course of their grand tours of the solar system, the Voyagers took tens of thousands of images and measurements that significantly changed our understanding of the outer planets.

At Jupiter, they gave us our first detailed ideas of how the planet’s atmosphere moves and evolves, showing that the Great Red Spot was a counter-clockwise rotating storm that interacted with other, smaller storms. They were also the first missions to spot a faint, dusty ring around Jupiter. Finally, they observed some of Jupiter’s moons, discovering Io’s volcanism, finding the linear features on Europa that were among the first hints that it might have an ocean beneath its surface, and granting Ganymede the title of largest moon in the solar system, a superlative that was previously thought to belong to Saturn’s moon Titan.

Saturn findings

Next, each spacecraft flew past Saturn, where they measured the composition and structure of Saturn’s atmosphere , and Voyager 1 also peered into Titan’s thick haze. Its observations led to the idea that Titan might have liquid hydrocarbons on its surface, a hypothesis that has since been verified by other missions. When the two missions observed Saturn’s rings, they found the gaps and waves that are well-known today. Voyager 1 also spotted three previously-unknown moons orbiting Saturn: Atlas, Prometheus, and Pandora.

Uranus and Neptune findings

After this, Voyager 1 headed out of the solar system, while Voyager 2 headed toward Uranus . There, it found 11 previously-unknown moons and two previously-unknown rings. Many of the phenomena it observed on Uranus remained unexplained, such as its unusual magnetic field and an unexpected lack of major temperature changes at different latitudes.

Voyager 2’s final stop, 12 years after it left Earth, was Neptune. When it arrived , it continued its streak of finding new moons with another haul of 6 small satellites, as well as finding rings around Neptune. As it did at Uranus, it observed the planet’s composition and magnetic field. It also found volcanic vents on Neptune’s huge moon Triton before it joined Voyager 1 on the way to interstellar space.

Interstellar space

Interstellar space begins at the heliopause, where the solar wind – a flow of charged particles released by the sun – is too weak to continue pushing against the interstellar medium, and the pressure from the two balances out. Voyager 1 officially entered interstellar space in August 2012, and Voyager 2 joined it  in November 2018.

These exits were instrumental in enabling astronomers to determine where exactly the edge of interstellar space is, something that’s difficult to measure from within the solar system. They showed that interstellar space begins just over 18 billion kilometers (about 11 billion miles) from the sun. The spacecraft continue to send back data on the structure of the interstellar medium.

After its planetary encounters, Voyager 1 took the iconic “Pale Blue Dot” image , showing Earth from about 6 billion kilometers (3.7 billion miles) away. As of 2021 , Voyager 1 is about 155 astronomical units (14.4 billion miles) from Earth, and Voyager 2 is nearly 129 astronomical units (12 billion miles) away.

The golden records

Each Voyager spacecraft has a golden phonograph record affixed to its side, intended as time capsules from Earth to any extraterrestrial life that might find the probes sometime in the distant future. They are inscribed with a message from Jimmy Carter, the U.S. President at the time of launch, which reads: “This is a present from a small, distant world, a token of our sounds, our science, our images, our music, our thoughts and our feelings. We are attempting to survive our time so we may live into yours.”

The covers of the records have several images inscribed, including visual instructions on how to play them, a map of our solar system’s location with respect to a set of 14 pulsars, and a drawing of a hydrogen atom. They are plated with uranium – its rate of decay will allow any future discoverers of either of the records to calculate when they were created.

The records’ contents were selected by a committee chaired by Carl Sagan. Each contains 115 images, including scientific diagrams of the solar system and its planets, the flora and fauna of Earth, and examples of human culture. There are natural sounds, including breaking surf and birdsong, spoken greetings in 55 languages, an hour of brainwave recordings, and an eclectic selection of music ranging from Beethoven to Chuck Berry to a variety of folk music.

Learn more Voyager Mission Status Bulletin Archives Experience A Message From Earth - Inspired by the Voyager Golden Record Neptune, planet of wind and ice

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Where is Voyager 1 heading?

NASA's Voyager 1 probe is heading toward an encounter with a distant star, about 40,000 years from now.

• By Mike Wall Space.com

September 13, 2013

Now that NASA 's Voyager 1 probe has left the solar system, its next big spaceflight milestone comes with the flyby of another star — in 40,000 years.

Voyager 1 entered interstellar space  in August 2012, nearly 35 years after blasting off, scientists announced Thursday (Sept. 12). As it leaves our solar system behind, the robotic spacecraft is streaking toward an encounter with a star called AC +79 3888, which lies 17.6 light-years from Earth.

"Voyager's on its way to a close approach with it in about 40,000 years," Voyager project manager Suzanne Dodd, of NASA's Jet Propulsion Laboratory in Pasadena , Calif., told reporters Thursday. "It's going to come within 1.7 light-years of this star — and it'll swing by it, and it will continue to orbit around the center of our Milky Way galaxy." [ Voyager 1 in Interstellar Space: Complete Coverage ]

The probe won't beam home any data from AC +79 3888's neighborhood, of course. Voyager 1's declining power supply will force the mission team to turn off its first instrument in 2020, and all of the science gear will stop working by 2025, Dodd said.

That time window still gives  Voyager 1  a dozen years or so to study interstellar space up close, and researchers can't wait to see what the probe observes in this unexplored realm.

For example, the spacecraft's data should shed light on how interstellar plasma flows around the heliosphere — the huge bubble of charged particles and magnetic fields that the sun puffs out around itself — said Voyager chief scientist Ed Stone, a physicist at the California Institute of Technology in Pasadena.

"So now, we will be able to understand and measure and observe that interaction, which is a very important part of how the sun interacts with what's around it," Stone told SPACE.com .

Voyager 1 and its twin, Voyager 2 , launched a few weeks apart in 1977 to study Jupiter, Saturn , Uranus and Neptune . The duo completed this unprecedented "grand tour" in 1989, and then embarked on a new mission to investigate the outer reaches of the solar system and  interstellar space .

Voyager 1, which is zipping along at 38,000 mph (61,000 km/h), is currently 11.7 billion miles (18.8 billion kilometers) from Earth. Voyager 2 took a different route through the solar system and is now 9.5 billion miles (15.3 billion km) from home.

Voyager 2 may join its twin in interstellar space three or four years from now, Stone said, stressing that it's tough to predict a departure date in advance.

Follow Mike Wall on Twitter  @michaeldwall  and  Google+ . Follow us  @Spacedotcom ,  Facebook  or  Google+ . Originally published on  SPACE.com.

• Voyager 1 Spacecraft's Road to Interstellar Space: A Photo Timeline
• Voyager 1 Goes Interstellar: Solar System Boundary Passed | Video
• 5 Facts About NASA's Far-Flung Voyager Spacecraft

Copyright 2013  SPACE.com , a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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NEWS... BUT NOT AS YOU KNOW IT

Nasa Voyager 1: What does it do and where in space is it right now?

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Nasa’s spacecraft Voyager 1 has been travelling in interstellar space for more than a decade.

Unsurprisingly, its findings pique the interest of scientists and… just about everybody else, given that it is the farthest manmade object from Earth, going further than any probe in history.

It is back in the news as of May 2022 – as Nasa reveals it has been sending back puzzling data .

Information from the probe’s attitude articulation and control system (AACS) doesn’t quite add up with what’s happening on board, apparently, leaving experts confused.

Back in 2021, Voyager 1 made headlines for picking up a faint hum coming from beyond the edge of our solar system .

Curious? Understandably so. Here’s a bit more information about Voyager 1.

What is Nasa Voyager 1 and what does it do?

Voyager 1 launched in 1977, along with another Nasa space probe called Voyager 2.

It initially travelled through our solar system, reaching interstellar space – beyond the heliosphere, ‘a protective bubble’ created by our solar system’s star, the Sun – in 2012.

Voyager 1 is the first probe to have reached interstellar space, with another spacecraft Pioneer 10 and also Voyager 2 making the fateful crossing at later dates.

Originally, the probe was designed to explore planets in the outer reaches of the solar system, Jupiter and Saturn, but has continued to operate far longer than expected.

Voyager 1 sends back different types of data to Earth, with significant discoveries emerging in the 1970s/1980s.

It discovered two Jupiter moons, Thebe and Metis, as well as a thin ring around the planet. Upon reaching Saturn, it found a new G-ring plus five then-unknown moons.

Voyager 1 then took around 60 incredible ‘family portraits’ of the Sun with its planets in 1990, at which point the camera was turned off – to save energy for the interstellar mission announced that year.

Nasa says that one major goal for the mission was to collect data regarding the transition from the heliosphere, through the heliopause and into interstellar space.

Just in case the probe runs into any aliens, it contains a vinyl-like disc of greetings in human languages, sounds from Earth and a message from then US president Jimmy Carter.

Symbols showing how to play the disc using a needle and cartridge are also included.

A full timeline of Voyager 1’s history is available on Nasa’s website .

Where exactly in space is the Nasa Voyager 1?

Voyager 1 is nearly 14.5 billion miles – or 155.6 astronomical units (AU) – away from planet Earth. It’s already more than 14.5 billion miles from the Sun.

These numbers continue to increase, as the probe is moving fast. You can see its progress on the live Nasa Mission Status tracker .

Eventually, Voyager 1 will reach other destinations in thousands of years’ time.

Nasa’s website reads: ‘In about 40,000 years, Voyager 1 will drift within 1.6 light years (9.3 trillion miles) of AC+79 3888, a star in the constellation of Camelopardalis which is heading toward the constellation Ophiuchus.’

However, it (obviously) won’t be sending home data then. Nasa says science data is expected to stop around 2025.

MORE : Nasa puzzled by ‘mysterious’ signals from Voyager space probe

MORE : Nasa warns asteroid larger than two football pitches is heading towards Earth

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Whatever happened to the Voyager spacecraft?

As the MIR moves outward from the Sun, it eventually will cross the termination shock, where the solar wind collides with the interstellar wind and slows. From there, the gas will continue until it reaches the heliopause, the edge of the heliosphere. There, it will mix with cooler gas in the interstellar medium.

If the MIR has retained sufficient energy, this event will create low-frequency radio waves that both Voyagers can detect. Scientists can calculate the distance to the heliopause — and, by inference, the termination shock — by comparing the arrival time of the MIR’s radio signal with the time the shock passed the spacecraft. One of the science goals of what we now call the Voyager Interstellar Mission is to encounter the termination shock so we can observe interactions between the solar wind and its interstellar counterpart.

In fact, Voyager 1 may be close already. Recent observations indicate Voyager 1 is in a region unlike any it has encountered in all its years of exploration. Some scientists believe Voyager 1 has begun its passage through the termination shock, but the phenomena we observe are somewhat different than what was expected. So the debate continues while scientists try to understand what the spacecraft’s instruments are telling us. If Voyager 1 has encountered the termination shock, it would be the first spacecraft to have entered the solar system’s final frontier, a vast expanse where wind from the Sun blows hot against the thin, cold gas between the stars. — ED B. MASSEY, GODDARD SPACE FLIGHT CENTER, GREENBELT, MARYLAND

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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's interstellar Voyager 1 spacecraft isn't doing so well — here's what we know

Since late 2023, engineers have been trying to get the Voyager spacecraft back online.

On Dec. 12, 2023, NASA shared some worrisome news about Voyager 1, the first probe to walk away from our solar system 's gravitational party and enter the isolation of interstellar space . Surrounded by darkness, Voyager 1 seems to be glitching. 

It has been out there for more than 45 years, having supplied us with a bounty of treasure like the discovery of two new moons of Jupiter, another incredible ring of Saturn and the warm feeling that comes from knowing pieces of our lives will drift across the cosmos even after we're gone. (See: The Golden Record .) But now, Voyager 1 's fate seems to be uncertain.

As of Feb. 6, NASA said the team remains working on bringing the spacecraft back to proper health. "Engineers are still working to resolve a data issue on Voyager 1," NASA's Jet Propulsion Laboratory said in a post on X (formerly Twitter). "We can talk to the spacecraft, and it can hear us, but it's a slow process given the spacecraft's incredible distance from Earth."

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

So, on the bright side, even though Voyager 1 sits so utterly far away from us, ground control can actually communicate with it. In fact, last year, scientists beamed some software updates to the spacecraft as well as its counterpart, Voyager 2 , from billions of miles away. Though on the dimmer side, due to that distance, a single back-and-forth communication between Voyager 1 and anyone on Earth takes a total of 45 hours. If NASA finds a solution, it won't be for some time .

The issue, engineers realized, has to do with one of Voyager 1's onboard computers known as the Flight Data System, or FDS. (The backup FDS stopped working in 1981.)

"The FDS is not communicating properly with one of the probe's subsystems, called the telemetry modulation unit (TMU)," NASA said in a blog post. "As a result, no science or engineering data is being sent back to Earth." This is of course despite the fact that ground control can indeed send information to Voyager 1, which, at the time of writing this article , sits about 162 AU's from our planet. One AU is equal to the distance between the Earth and the sun , or 149,597,870.7 kilometers (92,955,807.3 miles).

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From the beginning 

Voyager 1's FDS dilemma was first noticed last year , after the probe's TMU stopped sending back clear data and started procuring a bunch of rubbish. 

As NASA explains in the blog post, one of the FDS' core jobs is to collect information about the spacecraft itself, in terms of its health and general status. "It then combines that information into a single data 'package' to be sent back to Earth by the TMU," the post says. "The data is in the form of ones and zeros, or binary code." 

However, the TMU seemed to be shuffling back a non-intelligible version of binary code recently. Or, as the team puts it, it seems like the system is "stuck." Yes, the engineers tried turning it off and on again. 

That didn't work. 

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Then, in early February, Suzanne Dodd, Voyager project manager at NASA's Jet Propulsion Laboratory, told Ars Technica that the team might have pinpointed what's going on with the FDS at last. The theory is that the problem lies somewhere with the FDS' memory; there might be a computer bit that got corrupted. Unfortunately, though, because the FDS and TMU work together to relay information about the spacecraft's health, engineers are having a hard time figuring out where exactly the possible corruption may exist. The messenger is the one that needs a messenger.

They do know, however, that the spacecraft must be alive because they are receiving what's known as a "carrier tone." Carrier tone wavelengths don't carry information, but they are signals nonetheless, akin to a heartbeat. It's also worth considering that Voyager 1 has experienced problems before, such as in 2022 when the probe's "attitude articulation and control system" exhibited some blips that were ultimately patched up. Something similar happened to Voyager 2 during the summer of 2023, when Voyager 1's twin suffered some antenna complications before coming right back online again.

Still, Dodd says this situation has been the most serious since she began working on the historic Voyager mission.

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].

Monisha Ravisetti is Space.com's Astronomy Editor. She covers black holes, star explosions, gravitational waves, exoplanet discoveries and other enigmas hidden across the fabric of space and time. Previously, she was a science writer at CNET, and before that, reported for The Academic Times. Prior to becoming a writer, she was an immunology researcher at Weill Cornell Medical Center in New York. She graduated from New York University in 2018 with a B.A. in philosophy, physics and chemistry. She spends too much time playing online chess. Her favorite planet is Earth.

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• Classical Motion There must be more to this story. Let me see if I have this right. They can receive a carrier. But the modulator gives them junk. Or possibly the processor's memory. And they can send new software. New instructions. So, why not simply use the packet data, to key the carrier on and off. OOK On and Off Keying. Telegraphy. Reply

Admin said: NASA's Voyager 1 deep space probe started glitching last year, and scientists aren't sure they can fix it. NASA's interstellar Voyager 1 spacecraft isn't doing so well — here's what we know : Read more

• Classical Motion I wish something would kick one of them back to us. I would love to see an analysis of every cubic cm of it. Reply
• billslugg Modulating the carrier wave would do no good unless the carrier knew what information to send us. The unit that failed takes the raw data and then tells the carrier what to say. Without the modulation unit there is no data to send. Reply

Classical Motion said: I wish something would kick one of them back to us. I would love to see an analysis of every cubic cm of it.

• Classical Motion I read that they were not sure if it was the modulator or the packet memory. The packet buffer. If they can send patch, it's easy to relocate that buffer into another section of memory. This can be done at several different memory locations to verify if it is a memory problem. If that works, then the modulator is ok. If the modulator fails with all those buffers, then it's the modulator. Turn off modulator. Just enable the carrier for a certain duration for a 1 bit. And turn it off for that certain duration for a 0 bit. One simply rotates that buffer string thru the accumulator at the duration rate, and use status flags to key the transmitter. Very simple and very short code. The packet is nothing more that a 128 BYTE or multiple size string of 1s and 0s. OOK is a very common wireless modulation. That's why I commented on more must be going on. And I would like to see what 30 years naked in space does to man molded matter. Reply

Classical Motion said: I read that they were not sure if it was the modulator or the packet memory. The packet buffer. If they can send patch, it's easy to relocate that buffer into another section of memory. This can be done at several different memory locations to verify if it is a memory problem. If that works, then the modulator is ok. If the modulator fails with all those buffers, then it's the modulator. Turn off modulator. Just enable the carrier for a certain duration for a 1 bit. And turn it off for that certain duration for a 0 bit. One simply rotates that buffer string thru the accumulator at the duration rate, and use status flags to key the transmitter. Very simple and very short code. The packet is nothing more that a 128 BYTE or multiple size string of 1s and 0s. OOK is a very common wireless modulation. That's why I commented on more must be going on. And I would like to see what 30 years naked in space does to man molded matter.

• damienassurre I think they should make another space craft and have it pick up voyager 1 and bring it back the info it went through would very valuable to stellar travel Reply

damienassurre said: I think they should make another space craft and have it pick up voyager 1 and bring it back the info it went through would very valuable to stellar travel

• billslugg The newer forms of memory can't be used easily in outer space as their feature size is too small and too easily corrupted by a cosmic ray. Very large, bulky features keep spacecraft memory far smaller than what earthbound computers can enjoy. As far as returning one of the Voyagers to Earth, it would take several thousand years using available technology. Better to wait for more advanced propulsion technologies. Reply
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Asteroid bigger than the Empire State Building hurtling towards Earth as Nasa hires man to stop it

A n asteroid larger than the Empire State Building is heading towards Earth - and one man has detailed his role in Nasa's billion-dollar plan to stop it before it's too late.

The snappily-named 101955 Bennu is 490 metres across - almost 50m larger than the New York City landmark - meaning any impact with Earth could be cataclysmic.

The asteroid only has a one in 1,750 chance of actually hitting us - and even then, we'll have to wait for September 24, 2182 - but Nasa has already taken steps to mitigate the destruction an interstellar boulder like this will bring.

Those steps involved hiring Dante Lauretta, 54, a planetary science and cosmochemistry professor at the University of Arizona, to head up a mission to research, chart and even sample 101955 Bennu.

In an excerpt from his book, "The Asteroid Hunter: a Scientist's Journey to the Dawn of our Solar System", Lauretta detailed what the risk to life on Earth might look like if space agencies around the world didn't take reasonable precaution.

He said: "If it hits Earth, its path will blaze through the atmosphere many times brighter than the midday sun. The impact will release a blast of energy equivalent to 1,450 megatons of TNT."

The professor said that such a release of energy would make the combined historical payload of all humanity's nuclear testing - a paltry 510 megatons - pale in comparison.

The asteroid's initial impact would result in a mile-deep crater the size of Liverpool, and an earthquake clocking in at 6.7 on the Richter scale - the size of the 1994 Northridge quake which injured thousands and cost billions of dollars to clean up.

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Prof Lauretta said: "The sound wave would be louder than an orchestra of air-raid sirens, blaring from every direction.

"Curious onlookers who flocked to their windows to view the fireball would be greeted with a barrage of fragments as the glass imploded.

"Residential homes would be flattened, the few survivors determined by location and random luck.

"Office buildings and highway bridges would twist, distort, and ultimately collapse. Trees would be blown down; those that somehow managed to remain upright would be stripped of their branches and leaves."

Given the asteroid would, as Prof Lauretta says, be "a major natural and humanitarian disaster" yielding a "staggering" death toll, Nasa launched the OSIRIS-REx mission to study it - even taking a sample from the rock, returning it to Earth's surface for testing in September last year.

Nasa said the mission "will help scientists investigate how planets formed and how life began, as well as improve our understanding of asteroids that could impact Earth".

And OSIRIS-REx isn't the only Nasa mission to make contact with a celestial body - the space agency is also developing cutting-edge technology for ‘planetary defence’, with 2022’s Dart mission marking their first attempt to move an asteroid in space.

Both missions could be crucial in staving off the threat of an asteroid impact - even if we may be long gone by the time 101955 Bennu touches down.

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Voyager 1 starts making sense again after months of babble

Veteran spacecraft shows signs of sanity with poke from engineers.

Engineers are hopeful the veteran spacecraft Voyager 1 has turned a corner after spending the past three months spouting gibberish at controllers.

On March 1 , the Voyager team sent a command, dubbed a "poke," to get the probe's Flight Data System (FDS) to try some other sequences in its software in the hope of circumventing whatever had become corrupted.

Readers of a certain vintage will doubtless have memories of poke sheets for various 1980s games. Not that this hack ever used a poke to get infinite lives in Jet Set Willy , of course.

While Voyager 1's lifespan is not infinite, it has endured far longer than anticipated and might be about to dodge yet another bullet. On March 3, the mission team saw something different in the stream of data returned from the spacecraft, which had been unreadable since December.

An engineer with the Deep Space Network (DSN) was able to decode it, and by March 10, the team determined that it contained a complete memory dump from the FDS.

The FDS memory read-out contains its code, variables, and science and engineering data for downlink.

Prior to NASA's announcement, Dr Suzanne Dodd, project manager for the Voyager Interstellar Mission, said in a Pasadena Star-News report that the data being transmitted from the probe was "not exactly what we would expect, but they do look like something that can show us that the FDS is at least partially working."

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Dodd was referring to the ones and zeroes streaming from the spacecraft. Previously, the probe's telemetry modulation unit (TMU) had begun in mid-December transmitting a repeating binary pattern as though it was somehow stuck. Engineers reckoned the issue was somewhere within the FDS.

The next step is to study the memory read-out and compare it to one transmitted before the problem arose. A solution to the issue could then be devised.

One of the original Voyager scientists, Garry Hunt, told The Register that engineers at JPL were determined to get communications with the stricken probe working again: "This requires both skills and patience with the long time between communication instructions and response."

The time lag is a problem. A command from Earth takes 22.5 hours to reach the probe, and the same period is needed again for a response. This means a 45-hour wait to see what a given command might have done.

The availability of skills is also an issue. Many of the engineers who worked on the project - Voyager 1 launched in 1977 - are no longer around, and the team that remains is faced with trawling through reams of decades-old documents to deal with unanticipated issues arising today. ®

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• The Contents
• The Making of
• Where Are They Now
• Frequently Asked Questions
• Q & A with Ed Stone

golden record

Where are they now.

• frequently asked questions
• Q&A with Ed Stone

The Voyager Planetary Mission

The twin spacecraft Voyager 1 and Voyager 2 were launched by NASA in separate months in the summer of 1977 from Cape Canaveral, Florida. As originally designed, the Voyagers were to conduct closeup studies of Jupiter and Saturn, Saturn's rings, and the larger moons of the two planets.

To accomplish their two-planet mission, the spacecraft were built to last five years. But as the mission went on, and with the successful achievement of all its objectives, the additional flybys of the two outermost giant planets, Uranus and Neptune, proved possible -- and irresistible to mission scientists and engineers at the Voyagers' home at the Jet Propulsion Laboratory in Pasadena, California.

As the spacecraft flew across the solar system, remote-control reprogramming was used to endow the Voyagers with greater capabilities than they possessed when they left the Earth. Their two-planet mission became four. Their five-year lifetimes stretched to 12 and more.

Eventually, between them, Voyager 1 and 2 would explore all the giant outer planets of our solar system, 48 of their moons, and the unique systems of rings and magnetic fields those planets possess.

Had the Voyager mission ended after the Jupiter and Saturn flybys alone, it still would have provided the material to rewrite astronomy textbooks. But having doubled their already ambitious itineraries, the Voyagers returned to Earth information over the years that has revolutionized the science of planetary astronomy, helping to resolve key questions while raising intriguing new ones about the origin and evolution of the planets in our solar system.

History of the Voyager Mission

The Voyager mission was designed to take advantage of a rare geometric arrangement of the outer planets in the late 1970s and the 1980s which allowed for a four-planet tour for a minimum of propellant and trip time. This layout of Jupiter, Saturn, Uranus and Neptune, which occurs about every 175 years, allows a spacecraft on a particular flight path to swing from one planet to the next without the need for large onboard propulsion systems. The flyby of each planet bends the spacecraft's flight path and increases its velocity enough to deliver it to the next destination. Using this "gravity assist" technique, first demonstrated with NASA's Mariner 10 Venus/Mercury mission in 1973-74, the flight time to Neptune was reduced from 30 years to 12.

While the four-planet mission was known to be possible, it was deemed to be too expensive to build a spacecraft that could go the distance, carry the instruments needed and last long enough to accomplish such a long mission. Thus, the Voyagers were funded to conduct intensive flyby studies of Jupiter and Saturn only. More than 10,000 trajectories were studied before choosing the two that would allow close flybys of Jupiter and its large moon Io, and Saturn and its large moon Titan; the chosen flight path for Voyager 2 also preserved the option to continue on to Uranus and Neptune.

From the NASA Kennedy Space Center at Cape Canaveral, Florida, Voyager 2 was launched first, on August 20, 1977; Voyager 1 was launched on a faster, shorter trajectory on September 5, 1977. Both spacecraft were delivered to space aboard Titan-Centaur expendable rockets.

The prime Voyager mission to Jupiter and Saturn brought Voyager 1 to Jupiter on March 5, 1979, and Saturn on November 12, 1980, followed by Voyager 2 to Jupiter on July 9, 1979, and Saturn on August 25, 1981.

Voyager 1's trajectory, designed to send the spacecraft closely past the large moon Titan and behind Saturn's rings, bent the spacecraft's path inexorably northward out of the ecliptic plane -- the plane in which most of the planets orbit the Sun. Voyager 2 was aimed to fly by Saturn at a point that would automatically send the spacecraft in the direction of Uranus.

After Voyager 2's successful Saturn encounter, it was shown that Voyager 2 would likely be able to fly on to Uranus with all instruments operating. NASA provided additional funding to continue operating the two spacecraft and authorized JPL to conduct a Uranus flyby. Subsequently, NASA also authorized the Neptune leg of the mission, which was renamed the Voyager Neptune Interstellar Mission.

Voyager 2 encountered Uranus on January 24, 1986, returning detailed photos and other data on the planet, its moons, magnetic field and dark rings. Voyager 1, meanwhile, continues to press outward, conducting studies of interplanetary space. Eventually, its instruments may be the first of any spacecraft to sense the heliopause -- the boundary between the end of the Sun's magnetic influence and the beginning of interstellar space. (Voyager 1 entered Interstellar Space on August 25, 2012.)

Following Voyager 2's closest approach to Neptune on August 25, 1989, the spacecraft flew southward, below the ecliptic plane and onto a course that will take it, too, to interstellar space. Reflecting the Voyagers' new transplanetary destinations, the project is now known as the Voyager Interstellar Mission.

Voyager 1 is now leaving the solar system, rising above the ecliptic plane at an angle of about 35 degrees at a rate of about 520 million kilometers (about 320 million miles) a year. Voyager 2 is also headed out of the solar system, diving below the ecliptic plane at an angle of about 48 degrees and a rate of about 470 million kilometers (about 290 million miles) a year.

Both spacecraft will continue to study ultraviolet sources among the stars, and the fields and particles instruments aboard the Voyagers will continue to search for the boundary between the Sun's influence and interstellar space. The Voyagers are expected to return valuable data for two or three more decades. Communications will be maintained until the Voyagers' nuclear power sources can no longer supply enough electrical energy to power critical subsystems.

The cost of the Voyager 1 and 2 missions -- including launch, mission operations from launch through the Neptune encounter and the spacecraft's nuclear batteries (provided by the Department of Energy) -- is $865 million. NASA budgeted an additional $30 million to fund the Voyager Interstellar Mission for two years following the Neptune encounter.

Voyagers 1 and 2 are identical spacecraft. Each is equipped with instruments to conduct 10 different experiments. The instruments include television cameras, infrared and ultraviolet sensors, magnetometers, plasma detectors, and cosmic-ray and charged-particle sensors. In addition, the spacecraft radio is used to conduct experiments.

The Voyagers travel too far from the Sun to use solar panels; instead, they were equipped with power sources called radioisotope thermoelectric generators (RTGs). These devices, used on other deep space missions, convert the heat produced from the natural radioactive decay of plutonium into electricity to power the spacecraft instruments, computers, radio and other systems.

The spacecraft are controlled and their data returned through the Deep Space Network (DSN), a global spacecraft tracking system operated by JPL for NASA. DSN antenna complexes are located in California's Mojave Desert; near Madrid, Spain; and in Tidbinbilla, near Canberra, Australia.

The Voyager project manager for the Interstellar Mission is George P. Textor of JPL. The Voyager project scientist is Dr. Edward C. Stone of the California Institute of Technology. The assistant project scientist for the Jupiter flyby was Dr. Arthur L. Lane, followed by Dr. Ellis D. Miner for the Saturn, Uranus and Neptune encounters. Both are with JPL.

JUPITER Voyager 1 made its closest approach to Jupiter on March 5, 1979, and Voyager 2 followed with its closest approach occurring on July 9, 1979. The first spacecraft flew within 277,400 kilometers (172,368 miles) of the planet's cloud tops, and Voyager 2 came within 650,180 kilometers (404,003 miles).

Jupiter is the largest planet in the solar system, composed mainly of hydrogen and helium, with small amounts of methane, ammonia, water vapor, traces of other compounds and a core of melted rock and ice. Colorful latitudinal bands and atmospheric clouds and storms illustrate Jupiter's dynamic weather system. The giant planet is now known to possess 16 moons. The planet completes one orbit of the Sun each 11.8 years and its day is 9 hours, 55 minutes.

Although astronomers had studied Jupiter through telescopes on Earth for centuries, scientists were surprised by many of the Voyager findings.

The Great Red Spot was revealed as a complex storm moving in a counterclockwise direction. An array of other smaller storms and eddies were found throughout the banded clouds.

Discovery of active volcanism on the satellite Io was easily the greatest unexpected discovery at Jupiter. It was the first time active volcanoes had been seen on another body in the solar system. Together, the Voyagers observed the eruption of nine volcanoes on Io, and there is evidence that other eruptions occurred between the Voyager encounters.

Plumes from the volcanoes extend to more than 300 kilometers (190 miles) above the surface. The Voyagers observed material ejected at velocities up to a kilometer per second.

Io's volcanoes are apparently due to heating of the satellite by tidal pumping. Io is perturbed in its orbit by Europa and Ganymede, two other large satellites nearby, then pulled back again into its regular orbit by Jupiter. This tug-of-war results in tidal bulging as great as 100 meters (330 feet) on Io's surface, compared with typical tidal bulges on Earth of one meter (three feet).

It appears that volcanism on Io affects the entire jovian system, in that it is the primary source of matter that pervades Jupiter's magnetosphere -- the region of space surrounding the planet influenced by the jovian magnetic field. Sulfur, oxygen and sodium, apparently erupted by Io's many volcanoes and sputtered off the surface by impact of high-energy particles, were detected as far away as the outer edge of the magnetosphere millions of miles from the planet itself.

Europa displayed a large number of intersecting linear features in the low-resolution photos from Voyager 1. At first, scientists believed the features might be deep cracks, caused by crustal rifting or tectonic processes. The closer high-resolution photos from Voyager 2, however, left scientists puzzled: The features were so lacking in topographic relief that as one scientist described them, they "might have been painted on with a felt marker." There is a possibility that Europa may be internally active due to tidal heating at a level one-tenth or less than that of Io. Europa is thought to have a thin crust (less than 30 kilometers or 18 miles thick) of water ice, possibly floating on a 50-kilometer-deep (30-mile) ocean.

Ganymede turned out to be the largest moon in the solar system, with a diameter measuring 5,276 kilometers (3,280 miles). It showed two distinct types of terrain -- cratered and grooved -- suggesting to scientists that Ganymede's entire icy crust has been under tension from global tectonic processes.

Callisto has a very old, heavily cratered crust showing remnant rings of enormous impact craters. The largest craters have apparently been erased by the flow of the icy crust over geologic time. Almost no topographic relief is apparent in the ghost remnants of the immense impact basins, identifiable only by their light color and the surrounding subdued rings of concentric ridges.

A faint, dusty ring of material was found around Jupiter. Its outer edge is 129,000 kilometers (80,000 miles) from the center of the planet, and it extends inward about 30,000 kilometers (18,000 miles).

Two new, small satellites, Adrastea and Metis, were found orbiting just outside the ring. A third new satellite, Thebe, was discovered between the orbits of Amalthea and Io.

Jupiter's rings and moons exist within an intense radiation belt of electrons and ions trapped in the planet's magnetic field. These particles and fields comprise the jovian magnetosphere, or magnetic environment, which extends three to seven million kilometers toward the Sun, and stretches in a windsock shape at least as far as Saturn's orbit -- a distance of 750 million kilometers (460 million miles).

As the magnetosphere rotates with Jupiter, it sweeps past Io and strips away about 1,000 kilograms (one ton) of material per second. The material forms a torus, a doughnut-shaped cloud of ions that glow in the ultraviolet. Some of the torus's heavy ions migrate outward, and their pressure inflates the Jovian magnetosphere, while the more energetic sulfur and oxygen ions fall along the magnetic field into the planet's atmosphere, resulting in auroras.

Io acts as an electrical generator as it moves through Jupiter's magnetic field, developing 400,000 volts across its diameter and generating an electric current of 3 million amperes that flows along the magnetic field to the planet's ionosphere.

SATURN The Voyager 1 and 2 Saturn flybys occurred nine months apart, with the closest approaches falling on November 12 and August 25, 1981. Voyager 1 flew within 64,200 kilometers (40,000 miles) of the cloud tops, while Voyager 2 came within 41,000 kilometers (26,000 miles).

Saturn is the second largest planet in the solar system. It takes 29.5 Earth years to complete one orbit of the Sun, and its day was clocked at 10 hours, 39 minutes. Saturn is known to have at least 17 moons and a complex ring system. Like Jupiter, Saturn is mostly hydrogen and helium. Its hazy yellow hue was found to be marked by broad atmospheric banding similar to but much fainter than that found on Jupiter. Close scrutiny by Voyager's imaging systems revealed long-lived ovals and other atmospheric features generally smaller than those on Jupiter.

Perhaps the greatest surprises and the most puzzles were found by the Voyagers in Saturn's rings. It is thought that the rings formed from larger moons that were shattered by impacts of comets and meteoroids. The resulting dust and boulder- to house-size particles have accumulated in a broad plane around the planet varying in density.

The irregular shapes of Saturn's eight smallest moons indicates that they too are fragments of larger bodies. Unexpected structure such as kinks and spokes were found in addition to thin rings and broad, diffuse rings not observed from Earth. Much of the elaborate structure of some of the rings is due to the gravitational effects of nearby satellites. This phenomenon is most obviously demonstrated by the relationship between the F-ring and two small moons that "shepherd" the ring material. The variation in the separation of the moons from the ring may the ring's kinked appearance. Shepherding moons were also found by Voyager 2 at Uranus.

Radial, spoke-like features in the broad B-ring were found by the Voyagers. The features are believed to be composed of fine, dust-size particles. The spokes were observed to form and dissipate in time-lapse images taken by the Voyagers. While electrostatic charging may create spokes by levitating dust particles above the ring, the exact cause of the formation of the spokes is not well understood.

Winds blow at extremely high speeds on Saturn -- up to 1,800 kilometers per hour (1,100 miles per hour). Their primarily easterly direction indicates that the winds are not confined to the top cloud layer but must extend at least 2,000 kilometers (1,200 miles) downward into the atmosphere. The characteristic temperature of the atmosphere is 95 kelvins.

Saturn holds a wide assortment of satellites in its orbit, ranging from Phoebe, a small moon that travels in a retrograde orbit and is probably a captured asteroid, to Titan, the planet-sized moon with a thick nitrogen-methane atmosphere. Titan's surface temperature and pressure are 94 kelvins (-292 Fahrenheit) and 1.5 atmospheres. Photochemistry converts some atmospheric methane to other organic molecules, such as ethane, that is thought to accumulate in lakes or oceans. Other more complex hydrocarbons form the haze particles that eventually fall to the surface, coating it with a thick layer of organic matter. The chemistry in Titan's atmosphere may strongly resemble that which occurred on Earth before life evolved.

The most active surface of any moon seen in the Saturn system was that of Enceladus. The bright surface of this moon, marked by faults and valleys, showed evidence of tectonically induced change. Voyager 1 found the moon Mimas scarred with a crater so huge that the impact that caused it nearly broke the satellite apart.

Saturn's magnetic field is smaller than Jupiter's, extending only one or two million kilometers. The axis of the field is almost perfectly aligned with the rotation axis of the planet.

URANUS In its first solo planetary flyby, Voyager 2 made its closest approach to Uranus on January 24, 1986, coming within 81,500 kilometers (50,600 miles) of the planet's cloud tops.

Uranus is the third largest planet in the solar system. It orbits the Sun at a distance of about 2.8 billion kilometers (1.7 billion miles) and completes one orbit every 84 years. The length of a day on Uranus as measured by Voyager 2 is 17 hours, 14 minutes.

Uranus is distinguished by the fact that it is tipped on its side. Its unusual position is thought to be the result of a collision with a planet-sized body early in the solar system's history. Given its odd orientation, with its polar regions exposed to sunlight or darkness for long periods, scientists were not sure what to expect at Uranus.

Voyager 2 found that one of the most striking influences of this sideways position is its effect on the tail of the magnetic field, which is itself tilted 60 degrees from the planet's axis of rotation. The magnetotail was shown to be twisted by the planet's rotation into a long corkscrew shape behind the planet.

The presence of a magnetic field at Uranus was not known until Voyager's arrival. The intensity of the field is roughly comparable to that of Earth's, though it varies much more from point to point because of its large offset from the center of Uranus. The peculiar orientation of the magnetic field suggests that the field is generated at an intermediate depth in the interior where the pressure is high enough for water to become electrically conducting.

Radiation belts at Uranus were found to be of an intensity similar to those at Saturn. The intensity of radiation within the belts is such that irradiation would quickly darken (within 100,000 years) any methane trapped in the icy surfaces of the inner moons and ring particles. This may have contributed to the darkened surfaces of the moons and ring particles, which are almost uniformly gray in color.

A high layer of haze was detected around the sunlit pole, which also was found to radiate large amounts of ultraviolet light, a phenomenon dubbed "dayglow." The average temperature is about 60 kelvins (-350 degrees Fahrenheit). Surprisingly, the illuminated and dark poles, and most of the planet, show nearly the same temperature at the cloud tops.

Voyager found 10 new moons, bringing the total number to 15. Most of the new moons are small, with the largest measuring about 150 kilometers (about 90 miles) in diameter.

The moon Miranda, innermost of the five large moons, was revealed to be one of the strangest bodies yet seen in the solar system. Detailed images from Voyager's flyby of the moon showed huge fault canyons as deep as 20 kilometers (12 miles), terraced layers, and a mixture of old and young surfaces. One theory holds that Miranda may be a reaggregration of material from an earlier time when the moon was fractured by an violent impact.

The five large moons appear to be ice-rock conglomerates like the satellites of Saturn. Titania is marked by huge fault systems and canyons indicating some degree of geologic, probably tectonic, activity in its history. Ariel has the brightest and possibly youngest surface of all the Uranian moons and also appears to have undergone geologic activity that led to many fault valleys and what seem to be extensive flows of icy material. Little geologic activity has occurred on Umbriel or Oberon, judging by their old and dark surfaces.

All nine previously known rings were studied by the spacecraft and showed the Uranian rings to be distinctly different from those at Jupiter and Saturn. The ring system may be relatively young and did not form at the same time as Uranus. Particles that make up the rings may be remnants of a moon that was broken by a high-velocity impact or torn up by gravitational effects.

NEPTUNE When Voyager flew within 5,000 kilometers (3,000 miles) of Neptune on August 25, 1989, the planet was the most distant member of the solar system from the Sun. (Pluto once again will become most distant in 1999.)

Neptune orbits the Sun every 165 years. It is the smallest of our solar system's gas giants. Neptune is now known to have eight moons, six of which were found by Voyager. The length of a Neptunian day has been determined to be 16 hours, 6.7 minutes.

Even though Neptune receives only three percent as much sunlight as Jupiter does, it is a dynamic planet and surprisingly showed several large, dark spots reminiscent of Jupiter's hurricane-like storms. The largest spot, dubbed the Great Dark Spot, is about the size of Earth and is similar to the Great Red Spot on Jupiter. A small, irregularly shaped, eastward-moving cloud was observed "scooting" around Neptune every 16 hours or so; this "scooter," as Voyager scientists called it, could be a cloud plume rising above a deeper cloud deck.

Long, bright clouds, similar to cirrus clouds on Earth, were seen high in Neptune's atmosphere. At low northern latitudes, Voyager captured images of cloud streaks casting their shadows on cloud decks below.

The strongest winds on any planet were measured on Neptune. Most of the winds there blow westward, or opposite to the rotation of the planet. Near the Great Dark Spot, winds blow up to 2,000 kilometers (1,200 miles) an hour.

The magnetic field of Neptune, like that of Uranus, turned out to be highly tilted -- 47 degrees from the rotation axis and offset at least 0.55 radii (about 13,500 kilometers or 8,500 miles) from the physical center. Comparing the magnetic fields of the two planets, scientists think the extreme orientation may be characteristic of flows in the interiors of both Uranus and Neptune -- and not the result in Uranus's case of that planet's sideways orientation, or of any possible field reversals at either planet. Voyager's studies of radio waves caused by the magnetic field revealed the length of a Neptunian day. The spacecraft also detected auroras, but much weaker than those on Earth and other planets.

Triton, the largest of the moons of Neptune, was shown to be not only the most intriguing satellite of the Neptunian system, but one of the most interesting in all the solar system. It shows evidence of a remarkable geologic history, and Voyager 2 images showed active geyser-like eruptions spewing invisible nitrogen gas and dark dust particles several kilometers into the tenuous atmosphere. Triton's relatively high density and retrograde orbit offer strong evidence that Triton is not an original member of Neptune's family but is a captured object. If that is the case, tidal heating could have melted Triton in its originally eccentric orbit, and the moon might even have been liquid for as long as one billion years after its capture by Neptune.

An extremely thin atmosphere extends about 800 kilometer (500 miles) above Triton's surface. Nitrogen ice particles may form thin clouds a few kilometers above the surface. The atmospheric pressure at the surface is about 14 microbars, 1/70,000th the surface pressure on Earth. The surface temperature is about 38 kelvins (-391 degrees Fahrenheit) the coldest temperature of any body known in the solar system.

The new moons found at Neptune by Voyager are all small and remain close to Neptune's equatorial plane. Names for the new moons were selected from mythology's water deities by the International Astronomical Union, they are: Naiad, Thalassa, Despina, Galatea, Larissa, Proteus.

Voyager 2 solved many of the questions scientists had about Neptune's rings. Searches for "ring arcs," or partial rings, showed that Neptune's rings actually are complete, but are so diffuse and the material in them so fine that they could not be fully resolved from Earth. From the outermost in, the rings have been designated Adams, Plateau, Le Verrier and Galle.

Interstellar Mission

The spacecraft are continuing to return data about interplanetary space and some of our stellar neighbors near the edges of the Milky Way.

As the Voyagers cruise gracefully in the solar wind, their fields, particles and waves instruments are studying the space around them. In May 1993, scientists concluded that the plasma wave experiment was picking up radio emissions that originate at the heliopause -- the outer edge of our solar system.

The heliopause is the outermost boundary of the solar wind, where the interstellar medium restricts the outward flow of the solar wind and confines it within a magnetic bubble called the heliosphere. The solar wind is made up of electrically charged atomic particles, composed primarily of ionized hydrogen, that stream outward from the Sun.

Exactly where the heliopause is has been one of the great unanswered questions in space physics. By studying the radio emissions, scientists now theorize the heliopause exists some 90 to 120 astronomical units (AU) from the Sun. (One AU is equal to 150 million kilometers (93 million miles), or the distance from the Earth to the Sun.

The Voyagers have also become space-based ultraviolet observatories and their unique location in the universe gives astronomers the best vantage point they have ever had for looking at celestial objects that emit ultraviolet radiation.

The Ultraviolet Spectrometer (UVS) is the only experiment on the scan platform that is still functioning. The scan platform is parked at a fixed position and is not being articulated. The Infrared Spectrometer and Radiometer (IRIS) heater was turned off to save power on Voyager 1 on December 7, 2011. On January 21, 2014 the Scan Platform Supplemental Heater was also turned off to conserve power. The IRIS heater and the Scan Platform Heater were used to keep UVS warm. The UVS temperature has dropped to below the measurement limits of the sensor; however, UVS is still operating. The scientist expect to continue to receive data from the UVS until 2016, at which time the instrument will be turned off to save power.

Yet there are several other fields and particle instruments that can continue to send back data as long as the spacecraft stay alive. They include: the cosmic ray subsystem, the low-energy charge particle instrument, the magnetometer, the plasma subsystem, the plasma wave subsystem and the planetary radio astronomy instrument. Barring any catastrophic events, JPL should be able to retrieve this information for at least the next 20 and perhaps even the next 30 years.