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How fast are the Voyager spacecrafts travelling?

NASA's Voyage probes are speeding their way around the Solar System.

Keiron Allen

Asked by: Anonymous

Launched in 1977, NASA’s two Voyager probes surveyed Jupiter and Saturn, with Voyager 2 also visiting Uranus and Neptune before heading out of the Solar System. Voyager 1 has since become the fastest and most distant man-made object in the Universe, travelling at around 61,500km/h at a distance of 17.6 billion km from the Earth. Perhaps most incredible of all, NASA is still in communication with it, despite radio signals taking 16 hours to reach it.

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The remarkable twin Voyager spacecraft continue to explore the outer reaches of the solar system decades after they completed their surveys of the Outer Planets.  Launched in 1977 (September 5 for Voyager 1 (V1) and August 20 for Voyager 2 (V2), whose trajectory took it past Jupiter after Voyager 1), the spacecraft pair made many fundamental discoveries as they flew past Jupiter (March 1979 for V1, July 1979 for V2) and Saturn (November 1980 for V1, August 1981 for V2).  The path of Voyager 2 past Saturn was targeted so that it continued within the plane of the solar system, allowing it to become the first spacecraft to visit Uranus (January 1986) and Neptune (August 1989).  Following the Neptune encounter, both spacecraft started a new phase of exploration under the intriguing title of the Voyager Interstellar Mission.

Five instruments continue to collect important measurements of magnetic fields, plasmas, and charged particles as both spacecraft explore different portions of the solar system beyond the orbits of the planets.  Voyager 1 is now more than 118 astronomical units (one AU is equal to the average orbital distance of Earth from the Sun) distant from the sun, traveling at a speed (relative to the sun) of 17.1 kilometers per second (10.6 miles per second).  Voyager 2 is now more than 96 AU from the sun, traveling at a speed of 15.5 kilometers per second (9.6 miles per second).  Both spacecraft are moving considerably faster than Pioneers 10 and 11, two earlier spacecraft that became the first robotic visitors to fly past Jupiter and Saturn in the mid-70s.

This processed color image of Jupiter was produced in 1990 by the U.S. Geological Survey from a Voyager image captured in 1979. The colors have been enhanced to bring out detail. Zones of light-colored, ascending clouds alternate with bands of dark, descending clouds. The clouds travel around the planet in alternating eastward and westward belts at speeds of up to 540 kilometers per hour. Tremendous storms as big as Earthly continents surge around the planet. The Great Red Spot (oval shape toward the lower-left) is an enormous anticyclonic storm that drifts along its belt, eventually circling the entire planet.

As seen in the night sky at Earth, Voyager 1 is within the confines of the constellation Ophiuchus, only slightly above the celestial equator; no telescope can see it, but radio contact is expected to be maintained for at least the next ten years.  Voyager 2 is within the bounds of the constellation Telescopium (which somehow sounds quite appropriate) in the far southern night sky.

Both spacecraft have already passed something called the Termination Shock † (December 2004 for V1, August 2007 for V2), where the solar wind slows as it starts to interact with the particles and fields present between the stars.  It is expected that both spacecraft will encounter the Heliopause, where the solar wind ceases as true interstellar space begins, from 10 to 20 years after crossing the Termination Shock.  Theories exist for what should be present in interstellar space, but the Voyagers will become the first man-made objects to go beyond the influences of the Sun, hopefully returning the first measurements of what it is like out there.  Each spacecraft is carrying a metal record with encoded sounds and sights from Earth, along with the needle needed to read the recordings, and simplified instructions for where the spacecraft came from, in case they are eventually discovered by intelligent extra-terrestrials.

Keep track of the Voyager spacecraft on the official  Voyager Interstellar Mission website or follow  @NASAVoyager2 on Twitter.    † The sun ejects a continuous stream of charged particles (electrons, protons, etc) that is collectively termed the solar wind.  The particles are traveling extremely fast and are dense enough to form a very tenuous atmosphere; the heliosphere represents the volume of space where the effects of the solar wind dominate over those of particles in interstellar space.  The solar wind particles are moving very much faster than the local speed of sound represented by their low volume density.  When the particles begin to interact with interstellar particles and fields (the interaction can be either physically running into other particles or experiencing an electromagnetic force resulting from a charged particle moving within a magnetic field), then they start to slow down.  The point at which they become subsonic (rather than their normal hypersonic speed) is the Termination Shock.

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We Finally Know What Happened When Voyager 2 Reached Interstellar Space

A few big takeaways from the craft's incredible journey.

• The spacecraft reached the interstellar boundary between our solar system and interstellar space in 2018. Voyager 1 reached the boundary in 2012.
• Both spacecraft were launched in 1977, and have far surpassed scientists' expectations.

Scientists have finally analyzed data from Voyager 2’s journey to interstellar space and discovered a number of surprising differences—plus a few strange similarities.

Voyager 1 and 2 launched in August and October of 1977, respectively, and set out to explore the far reaches of the solar system and beyond. The spacecraft have revealed a vast amount of insight into distant planets and snapped pictures of previously undiscovered moons. Still, more than 40 years after their launch, they continue to provide scientists with an unparalleled look at the universe.

In 2012, Voyager 1 became the first spacecraft to reach interstellar space. Last year, Voyager 2 joined its companion in the interstellar medium, reaching the boundary set 119 times the Earth–sun distance away from Earth. The transition from our solar system to interstellar space, the researchers say, may take less than a day to cross. The data from Voyager 2’s crossing was published November 4 in a series of five papers in Nature Astronomy .

The heliopause is the theoretical boundary at which the sun’s solar wind meets interstellar winds, which are shot out from supernovae that have exploded millions of years ago. Additionally, galactic cosmic rays try to flow into our solar system, but only 30 percent of these rays actually reach Earth. Voyager 1 and 2 were also able to study changes in the magnetic fields within and outside of our solar system.

The two spacecraft reached interstellar space during different periods of solar activity, meaning conditions along the boundary were markedly different. Voyager 1 reached the interstellar boundary during the sun’s solar minimum, whereas Voyager 2 reached the boundary during the solar maximum, a period of heightened activity. Additionally, unlike its quicker counterpart, Voyager 2’s mission has largely taken place in Earth’s southern hemisphere.

The researchers also discovered that solar material was “leaking” out into the interstellar medium. “That was very different than what happened with Voyager 1, where hardly any material was leaking out,” said Tom Krimigis of John’s Hopkins’s Applied Physics Laboratory in an October 31 press conference.

In the case of Voyager 1, the team saw the opposite, where interstellar particles leaked into our solar system. The team hopes to reconvene to take a closer look at their data in the near future to understand how and why these particles slip out of the grasp of our solar system.

Another perplexing discovery? The direction of the magnetic fields both inside and outside of the heliopause is aligned, as was the case with Voyager 1. Leonard Burlaga of NASA Goddard Space Flight Center said scientists can dismiss the alignment of the magnetic fields once, but twice would be a remarkable coincidence. The strength of the magnetic field was stronger in interstellar space, the Voyager 2 found.

The scientists also discovered that the heliopause itself is much thinner and smoother than expected, and that the interstellar medium tucked close to the boundary layer, where solar and interstellar winds meet, is much hotter and unpredictable than expected. This newest research also revealed that the boundary layer itself may be more complex than initially thought, with multiple layers of different temperature, density, and speed.

Voyager 1 and 2 have roughly five years before they'll lose the use of their scientific instruments, said Ed Stone of the California Institute of Technology during the press conference. "When the two voyagers were launched, the space age was only 20 years old, Stone said. "So it was hard to know at that time that anything could last over 40 years."

There's still a lot left to explore, and the data dump has sparked a desire to explore faster, farther, and deeper into interstellar space.

Jennifer Leman is a science journalist and senior features editor at Popular Mechanics, Runner's World, and Bicycling. A graduate of the Science Communication Program at UC Santa Cruz, her work has appeared in The Atlantic, Scientific American, Science News and Nature. Her favorite stories illuminate Earth's many wonders and hazards.

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Voyager 2 Change-of-course Maneuver Successful

NASA's Voyager 2 spacecraft, now less than year away from its encounter with the planet Neptune, successfully completed critical change-of-course maneuver today that will bring Voyager 10,000 kilometers (6,200 miles) closer to the planet during its Neptune flyby next summer.

Voyager 2, operated by the Jet Propulsion Laboratory (JPL) in Pasadena, Calif., will pass about 5,000 kilometers (3,000 miles) from Neptune's cloudtops at 9 p.m. Pacific Daylight Time on Aug. 24, 1989. Five hours later, the spacecraft will also fly about 38,000 kilometers (24,000 miles) from Neptune's moon Triton, which may harbor lakes of liquid nitrogen.

Responding to commands radioed from Earth, Voyager 2 fired its hydrazine thrusters for 3 minutes and 29 seconds, beginning at 6:55 a.m. Pacific Standard Time today. Radio signals received from Voyager at JPL indicated that the maneuver was properly executed, according to Dr. Lanny Miller, manager of the Voyager flight engineering office.

Voyager 2, now 4.2 billion kilometers (2.6 billion miles) from Earth, is controlled by radio signals sent from giant dish antennas owned by NASA in California, Spain and Australia. Traveling at the speed of light (186,000 milesper second), the signals take nearly four hours to reach the spacecraft.

The Neptune flyby will be Voyager 2's fourth and final planetary encounter before the spacecraft heads out of the solar system to explore interstellar space. Voyager 2 was launched in 1977 along with twin spacecraft, Voyager 1. Voyager 1 completed flybys of Jupiter and Saturn and their moons, and is headed out of the solar system. After completing its Jupiter and Saturn encounters, Voyager 2 was sent on to explore Uranus, which it flew past in January 1986, and Neptune. The spacecraft is now 414.7 million kilometers (257.7 million miles) from Neptune.

The Voyager project is managed by JPL for NASA's Office of Space Science and Applications.

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Voyager 2’s Discoveries From Interstellar Space

In its journey beyond the boundary of the solar wind’s bubble, the probe observed some notable differences from its twin, Voyager 1.

By Kenneth Chang

The Voyager 2 spacecraft burst out of the bubble of gases expanding from the sun and into the wild of the Milky Way a year ago. It was the second spacecraft to cross that boundary and directly observe the interstellar medium. Its faster-moving twin, Voyager 1, made the crossing six years earlier, in August 2012.

Launched 42 years ago, when Jimmy Carter was president, the twin spacecraft have persisted far longer than envisioned, as has their ability to send scientific findings home to Earth.

In a series of papers published on Monday in Nature Astronomy, scientists report what Voyager 2 observed at the boundary of the solar wind’s bubble and beyond.

“We’re certainly surprised,” Edward C. Stone, the mission’s project scientist, said of the probe’s longevity during a news conference on Thursday. “We’re also wonderfully excited by the fact that they do. When the two Voyagers were launched, the space age was only 20 years old. It was hard to know at that time that anything could last over 40 years.”

In many ways, the measurements echoed Voyager 1’s: a jump in the density of particles accompanied by a sharp decrease in their speed, a shift in the magnetic fields.

Voyager 2 also noted some differences, which could give clues about the complicated dynamics in that region of the solar system.

The sun spews in all directions a continuous stream of particles called the solar wind traveling at a speed of a million miles per hour. The particles are mostly hydrogen, but, heated to some 3 million degrees Fahrenheit, the atoms are ripped apart into protons and electrons.

At a distance of more than 11 billion miles from the sun, the solar wind, thinning out, is increasingly buffeted by the flow of particles in the interstellar wind and a galactic magnetic field generated by the long ago explosions of distant stars. The interstellar wind is much cooler — just tens of thousands of degrees — and denser.

Voyager 2 is heading in a different direction than Voyager 1, which could explain some of the differences. The sun was also more active in 2012, near the maximum phase of its cycle of activity. The sun is now near its lull, known as the solar minimum.

With Voyager 1, the outward velocity of the solar wind dropped to zero long before the boundary; it was pushed sideways. With Voyager 2, the outward velocities fluctuated, sometimes dipping to zero but then rising again.

Curiously, the distances from the sun for the two crossings out of the solar system were similar. Scientists had expected that the bubble would be pushed outward during the solar maximum and collapse inward during the solar minimum.

“A lot of the models leave a lot to be desired,” Stamatios Krimigis, a scientists at the Johns Hopkins Applied Physics Laboratory in Laurel, Md., and the principal investigator of one of the Voyager instruments, said in an interview.

Voyager 2 also measured what scientists describe as a magnetic barrier, “like the pile-up of slowly moving cars on a major highway, a few miles ahead of the scene of an accident,” Leonard F. Burlaga, a scientist working with the spacecraft’s magnetometer, wrote in an email.

When solar wind slows, the density of particles increases and the magnetic field strengthens.

“Again, it’s like the cars, which turn away from the lanes of the accident and move slowly along the available lanes,” Dr. Burlaga said. “The cars are more densely spaced, the drivers are heated, but they eventually move along.”

The missions were originally designed to last four years to fly by Jupiter and Saturn. Voyager 2 also visited Uranus and Neptune. Voyager 2 still has five functioning instruments for measuring the void; Voyager 1 has four.

Both Voyagers are expected to last another five years or so until their batteries die out. Both are powered by electricity generated by the heat of radioactive plutonium. As the plutonium diminishes, the spacecraft receive less and less energy.

Once the Voyagers shut down, there will be no more data from beyond our solar system for years. Only one other spacecraft, the New Horizons probe that flew by Pluto in 2015 and visited another object in the distant Kuiper belt in January this year, is headed that way. But it is moving more slowly and its plutonium power will run out before it reaches interstellar space.

“Right now, when the Voyagers go offline, that’s kind of it unless we do something else,” said Ralph McNutt, a physicist at the Johns Hopkins Applied Physics Laboratory.

Dr. McNutt is leading a study to look at what it might take to build an ultrafast spacecraft that could leave the solar system in a hurry. The development of NASA’s long-delayed giant rocket, the Space Launch System, makes that mission more plausible.

The mission could also perform what is known as an Oberth maneuver, named after Hermann Oberth, a German physicist who came up with the idea in 1927. A probe would first head to Jupiter, using the giant planet’s gravity to accelerate toward the sun. As it then swings around the sun, the spacecraft would fire a rocket engine, accelerating to a speed where it could cover close to a couple of billion miles a year. That would be more than five times the speed of the Voyagers.

That would be tricky to pull off, however. For such a powered flyby to be effective, the probe would have to travel within a million miles or so from the sun.

“Well, it’s not as easy as it sounds,” said Dr. Krimigis, who is taking part in the study which should be completed in a couple of years. “At that distance, every metal we know melts.”

Kenneth Chang has been at The Times since 2000, writing about physics, geology, chemistry, and the planets. Before becoming a science writer, he was a graduate student whose research involved the control of chaos. More about Kenneth Chang

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First to visit all four giant planets

Voyager 2 is the only spacecraft to visit Uranus and Neptune. The probe is now in interstellar space, the region outside the heliopause, or the bubble of energetic particles and magnetic fields from the Sun.

Mission Type

What is Voyager 2?

NASA's Voyager 2 is the second spacecraft to enter interstellar space. On Dec. 10, 2018, the spacecraft joined its twin – Voyager 1 – as the only human-made objects to enter the space between the stars.

• Voyager 2 is the only spacecraft to study all four of the solar system's giant planets at close range.
• Voyager 2 discovered a 14th moon at Jupiter.
• Voyager 2 was the first human-made object to fly past Uranus.
• At Uranus, Voyager 2 discovered 10 new moons and two new rings.
• Voyager 2 was the first human-made object to fly by Neptune.
• At Neptune, Voyager 2 discovered five moons, four rings, and a "Great Dark Spot."

In Depth: Voyager 2

The two-spacecraft Voyager missions were designed to replace original plans for a “Grand Tour” of the planets that would have used four highly complex spacecraft to explore the five outer planets during the late 1970s.

NASA canceled the plan in January 1972 largely due to anticipated costs (projected at $1 billion) and instead proposed to launch only two spacecraft in 1977 to Jupiter and Saturn. The two spacecraft were designed to explore the two gas giants in more detail than the two Pioneers (Pioneers 10 and 11) that preceded them.

In 1974, mission planners proposed a mission in which, if the first Voyager was successful, the second one could be redirected to Uranus and then Neptune using gravity assist maneuvers.

Each of the two spacecraft was equipped with a slow-scan color TV camera to take images of the planets and their moons and each also carried an extensive suite of instruments to record magnetic, atmospheric, lunar, and other data about the planetary systems.

The design of the two spacecraft was based on the older Mariners, and they were known as Mariner 11 and Mariner 12 until March 7, 1977, when NASA Administrator James C. Fletcher (1919-1991) announced that they would be renamed Voyager.

Power was provided by three plutonium oxide radioisotope thermoelectric generators (RTGs) mounted at the end of a boom.

Voyager 2 at Jupiter

Voyager 2 began transmitting images of Jupiter April 24, 1979, for time-lapse movies of atmospheric circulation. Unlike Voyager 1, Voyager 2 made close passes to the Jovian moons on its way into the system, with scientists especially interested in more information from Europa and Io (which necessitated a 10 hour-long “volcano watch”).

During its encounter, it relayed back spectacular photos of the entire Jovian system, including its moons Callisto, Ganymede, Europa (at a range of about 127,830 miles or 205,720 kilometers, much closer than Voyager 1), Io, and Amalthea, all of which had already been surveyed by Voyager 1.

Voyager 2’s closest encounter to Jupiter was at 22:29 UT July 9, 1979, at a range of about 400,785 miles (645,000 kilometers). It transmitted new data on the planet’s clouds, its newly discovered four moons, and ring system as well as 17,000 new pictures.

When the earlier Pioneers flew by Jupiter, they detected few atmospheric changes from one encounter to the second, but Voyager 2 detected many significant changes, including a drift in the Great Red Spot as well as changes in its shape and color.

With the combined cameras of the two Voyagers, at least 80% of the surfaces of Ganymede and Callisto were mapped out to a resolution of about 3 miles (5 kilometers).

Voyager 2 at Saturn

Following a course correction two hours after its closest approach to Jupiter, Voyager 2 sped to Saturn, its trajectory determined to a large degree by a decision made in January 1981, to try to send the spacecraft to Uranus and Neptune later in the decade.

Its encounter with the sixth planet began Aug. 22, 1981, two years after leaving the Jovian system, with imaging of the moon Iapetus. Once again, Voyager 2 repeated the photographic mission of its predecessor, although it actually flew about 14,290 miles (23,000 kilometers) closer to Saturn. The closest encounter to Saturn was at 01:21 UT Aug. 26, 1981, at a range of about 63,000 miles (101,000 kilometers).

The spacecraft provided more detailed images of the ring “spokes” and kinks, and also the F-ring and its shepherding moons, all found by Voyager 1. Voyager 2’s data suggested that Saturn’s A-ring was perhaps only about 980 feet (300 meters) thick.

As it flew behind and up past Saturn, the probe passed through the plane of Saturn’s rings at a speed of 8 miles per second (13 kilometers per second). For several minutes during this phase, the spacecraft was hit by thousands of micron-sized dust grains that created “puff” plasma as they were vaporized. Because the vehicle’s attitude was repeatedly shifted by the particles, attitude control jets automatically fired many times to stabilize the vehicle.

During the encounter, Voyager 2 also photographed the Saturn moons Hyperion (the “hamburger moon”), Enceladus, Tethys, and Phoebe as well as the more recently discovered Helene, Telesto and Calypso.

Voyager 2 at Uranus

Although Voyager 2 had fulfilled its primary mission goals with the two planetary encounters, mission planners directed the veteran spacecraft to Uranus—a journey that would take about 4.5 years.

In fact, its encounter with Jupiter was optimized in part to ensure that future planetary flybys would be possible.

The Uranus encounter’s geometry was also defined by the possibility of a future encounter with Neptune: Voyager 2 had only 5.5 hours of close study during its flyby.

Voyager 2 was the first human-made object to fly past the planet Uranus.

Long-range observations of the planet began Nov. 4, 1985, when signals took approximately 2.5 hours to reach Earth. Light conditions were 400 times less than terrestrial conditions. Closest approach to Uranus took place at 17:59 UT Jan. 24, 1986, at a range of about 50,640 miles (81,500 kilometers).

During its flyby, Voyager 2 discovered 10 new moons (given such names as Puck, Portia, Juliet, Cressida, Rosalind, Belinda, Desdemona, Cordelia, Ophelia, and Bianca -- obvious allusions to Shakespeare), two new rings in addition to the “older” nine rings, and a magnetic field tilted at 55 degrees off-axis and off-center.

The spacecraft found wind speeds in Uranus’ atmosphere as high as 450 miles per hour (724 kilometers per hour) and found evidence of a boiling ocean of water some 497 miles (800 kilometers) below the top cloud surface. Its rings were found to be extremely variable in thickness and opacity.

Voyager 2 also returned spectacular photos of Miranda, Oberon, Ariel, Umbriel, and Titania, five of Uranus’ larger moons. In flying by Miranda at a range of only 17,560 miles (28,260 kilometers), the spacecraft came closest to any object so far in its nearly decade-long travels. Images of the moon showed a strange object whose surface was a mishmash of peculiar features that seemed to have no rhyme or reason. Uranus itself appeared generally featureless.

The spectacular news of the Uranus encounter was interrupted the same week by the tragic Challenger accident that killed seven astronauts during their space shuttle launch Jan. 28, 1986.

Voyager 2 at Neptune

Following the Uranus encounter, the spacecraft performed a single midcourse correction Feb. 14, 1986—the largest ever made by Voyager 2—to set it on a precise course to Neptune.

Voyager 2’s encounter with Neptune capped a 4.3 billion-mile (7 billion-kilometer) journey when, on Aug. 25, 1989, at 03:56 UT, it flew about 2,980 miles (4,800 kilometers) over the cloud tops of the giant planet, the closest of its four flybys. It was the first human-made object to fly by the planet. Its 10 instruments were still in working order at the time.

During the encounter, the spacecraft discovered six new moons (Proteus, Larissa, Despina, Galatea, Thalassa, and Naiad) and four new rings.

The planet itself was found to be more active than previously believed, with 680-mile (1,100-kilometer) per hour winds. Hydrogen was found to be the most common atmospheric element, although the abundant methane gave the planet its blue appearance.

Images revealed details of the three major features in the planetary clouds—the Lesser Dark Spot, the Great Dark Spot, and Scooter.

Voyager photographed two-thirds of Neptune’s largest moon Triton, revealing the coldest known planetary body in the solar system and a nitrogen ice “volcano” on its surface. Spectacular images of its southern hemisphere showed a strange, pitted cantaloupe-type terrain.

The flyby of Neptune concluded Voyager 2’s planetary encounters, which spanned an amazing 12 years in deep space, virtually accomplishing the originally planned “Grand Tour” of the solar system, at least in terms of targets reached if not in science accomplished.

Voyager 2's Interstellar Mission

Once past the Neptune system, Voyager 2 followed a course below the ecliptic plane and out of the solar system. Approximately 35 million miles (56 million kilometers) past the encounter, Voyager 2’s instruments were put in low power mode to conserve energy.

After the Neptune encounter, NASA formally renamed the entire project the Voyager Interstellar Mission (VIM).

Of the four spacecraft sent out to beyond the environs of the solar system in the 1970s, three of them -- Voyagers 1 and 2 and Pioneer 11 -- were all heading in the direction of the solar apex, i.e., the apparent direction of the Sun’s travel in the Milky Way galaxy, and thus would be expected to reach the heliopause earlier than Pioneer 10 which was headed in the direction of the heliospheric tail.

In November 1998, 21 years after launch, nonessential instruments were permanently turned off, leaving seven instruments still operating.

At 9.6 miles per second (15.4 kilometers per second) relative to the Sun, it will take about 19,390 years for Voyager 2 to traverse a single light year.

Asif Siddiqi

Beyond Earth: A Chronicle of Deep Space Exploration

Through the turn of the century, NASA's Jet Propulsion Laboratory (JPL) continued to receive ultraviolet and particle fields data. For example, on Jan. 12, 2001, an immense shock wave that had blasted out of the outer heliosphere on July 14, 2000, finally reached Voyager 2. During its six-month journey, the shock wave had plowed through the solar wind, sweeping up and accelerating charged particles. The spacecraft provided important information on high-energy shock-energized ions.

On Aug. 30, 2007, Voyager 2 passed the termination shock and then entered the heliosheath. By Nov. 5, 2017, the spacecraft was 116.167 AU (about 10.8 billion miles or about 17.378 billion kilometers) from Earth, moving at a velocity of 9.6 miles per second (15.4 kilometers per second) relative to the Sun, heading in the direction of the constellation Telescopium. At this velocity, it would take about 19,390 years to traverse a single light-year.

On July 8, 2019, Voyager 2 successfully fired up its trajectory correction maneuver thrusters and will be using them to control the pointing of the spacecraft for the foreseeable future. Voyager 2 last used those thrusters during its encounter with Neptune in 1989.

The spacecraft's aging attitude control thrusters have been experiencing degradation that required them to fire an increasing and untenable number of pulses to keep the spacecraft's antenna pointed at Earth. Voyager 1 had switched to its trajectory correction maneuver thrusters for the same reason in January 2018.

To ensure that both vintage robots continue to return the best scientific data possible from the frontiers of space, mission engineers are implementing a new plan to manage them. The plan involves making difficult choices, particularly about instruments and thrusters.

National Space Science Data Center: Voyager 2

A library of technical details and historic perspective.

A comprehensive history of missions sent to explore beyond Earth.

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Ready player two: where is Voyager 2 now

46 years of flying to infinity… That’s how long NASA’s Voyagers have been traveling through space. We’ve told you the story of Voyager 1 before, and now it’s the turn of its twin brother — Voyager 2. So, let’s dive into the details of the Voyager 2 mission.

General Voyager 2 facts

Voyager 2 is one of the most iconic and successful space probes ever launched by NASA. It is the first human-made object to fly by Neptune and Uranus, and the only spacecraft to study all four of the solar system’s giant planets at close range. Here are some key facts about Voyager 2:

• Voyager 2 launch date: August 20, 1977, from Cape Canaveral, Florida, aboard a Titan III-E/Centaur rocket.
• Primary mission objective: to learn the outer planets of the Solar System, including Jupiter, Saturn, Uranus, and Neptune, to study their atmospheres, magnetic fields, moons, and rings. Besides that similar to Voyager 1, Voyager 2 carries a “Golden Record” with sounds, images, and greetings from Earth, intended to communicate with potential extraterrestrial civilizations.
• Interstellar space : on November 5, 2018, Voyager 2 has exited the heliosphere (the region influenced by the Sun) and entered interstellar space. This made the probe the second human-made object to reach this milestone, after Voyager 1.
• Current mission status : Despite being launched 46 years ago, Voyager 2 is still operational and communicating with Earth. It continues to send back valuable data from the edge of our solar system, providing insights into the conditions of interstellar space.
• Current distance from Earth: over 19.9 billion kilometres (about 12.4 billion miles) or 133 A.U.

Planetary Flybys (closest approach):

• Jupiter: on July 9, 1979,
• Saturn: on August 25, 1981,
• Uranus: on January 24, 1986,
• Neptune: on August 25, 1989

How did the Voyager project originate?

The project idea originated in 1964 at the suggestion of Gary Flandro from NASA’s Jet Propulsion Laboratory. The young engineer pointed out that the alignment of the outer planets of the solar system, which occurs once every 175 years and was supposed to occur in the late 1970s, could allow one explorer to sequentially visit the systems of all four gas giants using a gravitational manoeuvre. Not wanting to miss this unique opportunity, NASA launched the Grand Tour program, in which it planned to build two new probes for two missions instead of one. The first launch was planned in 1977 (to Jupiter, Saturn and Pluto), and the second in 1979 to Jupiter, Uranus and Neptune. Such a scheme made it possible to reduce the total mission time, compared to the launch of one probe, by almost half: from 13 to 7.5 years.

But the American budget was not without limits, and in December 1971, the US Congress cancelled funding for the Grand Tour in favour of the already approved Space Shuttle program. Instead, NASA was asked to limit itself to visiting only two planets, Jupiter and Saturn, using two probes of the then-well-established Mariner class.

The program’s working title, Mariner Jupiter-Saturn, was changed to Voyager just a few months before launch. NASA felt that Mariner 11 and 12, improved specifically for the mission, were worthy of a separate name.

What is Voyager 2?

Voyager 2 is a space probe, unique, and so incredibly reliable and stable, that, even after 45 years of travelling into outer space, it is still proving itself. The probes are almost identical in design and set of scientific instruments. Each probe about five million parts, with minor differences due to different mission objectives.

Here are the specs of the Voyager 2 spacecraft:

Voyager 2 pictures

These photos from the NASA/SPL site help you to get an in-depth look at the science instruments aboard the Voyager spacecraft and the construction details of the probe.

When was Voyager 2 launched?

Voyager 2 launched on August 20, 1977, from Cape Canaveral SLC-41, on a Titan IIIE/Centaur launch vehicle.

Even though the study of Uranus and Neptune was not officially included in the mission program (a guaranteed reaching of these planets would require the construction of devices with more advanced characteristics), the flight trajectory was calculated based on this possibility.

Why was Voyager 2 launched first?

The launch order and flight paths of the probes were planned to ensure that the overall goals of the program were achieved.

Although Voyager 2 was launched 16 days before its companion, due to its longer trajectory, it should have reached Jupiter and Saturn later than Voyager 1 by 4 and 9 months, respectively. This made it possible to adjust the Voyager 2 flight program depending on the results obtained by Voyager 1; in particular, to decide whether to send it along the Grand Tour trajectory, that is, to Uranus and Neptune.

Besides, if the launch of Voyager 2 had failed, then Voyager 1 could have been sent along the Grand Tour trajectory.

Where did Voyager 2 visit?

During the first 12 years of its journey, Voyager 2 visited all four planets of the outer group, making a lot of important discoveries that significantly expanded the scientific understanding of these gas giants’ systems.

Between December 10, 1977, and October 21, 1978, Voyager 2 successfully crossed the asteroid belt and headed towards Jupiter. From April 24 to August 5, 1979, the probe made observations of Jupiter and its five satellites Callisto, Io, Ganymede, Amalthea and Europa, sending more than 17,000 images back to Earth. On July 9, 1979, the spacecraft made its closest approach to Jupiter at a distance of 350,000 miles from the planet’s upper layer clouds. Voyager 2 showed that the Great Red Spot is a complex system of storms, found signs of water on Io’s surface, confirmed the existence of a thin ring surrounding the planet, and discovered another moon beyond it, later named Adrastea.

Voyager 2 began its long-range observations of Saturn on June 5, 1981, when it was still 41 million miles away from the planet. By September 28, when observations of the Saturn system were completed, the spacecraft sent 16,000 images of the planet, its rings and moons back to Earth. On September 29, Voyager 2 fired its course correction thrusters to head towards its next target, Uranus.

Voyager 2 began observing Uranus on November 4, 1985, creating a series of time-lapse videos of the planet and its surroundings. Due to the axial tilt of Uranus by almost 98 degrees to its orbital plane (the planet is practically lying on its side), the meeting of Voyager 2 was like aiming for a bull’s eye. On January 24, 1986, about 11 hours before the closest approach, Voyager 2 entered the planet’s magnetosphere.

The encounter phase with Uranus was completed on February 25, 1986. What did Voyager 2 discover there? The spacecraft took over 7,000 pictures, revealing 11 new moons and two new rings.

Voyager 2 Neptune research continued from June 5 to October 2, 1989. The probe made more than 9,000 images of the planet and its surroundings, which helped to discover five new satellites of Proteus, Talas, Naiad, Despina, and Galatea, while also confirming the existence of the Larissa satellite. The probe also revealed traces of geysers on Triton that spew dark material into the rarefied atmosphere of the moon, which later settles back to its surface.

Interstellar space

After the reconnaissance of Neptune, Voyager 2 began its interstellar mission, which continues to this day. On November 5, 2018, the ship left the heliosphere and entered interstellar space.

On July 18, 2023, Voyager 2 overtook Pioneer 10 and became the second farthest spacecraft from the Sun after Voyager 1.

Where is Voyager 2 now in 2023?

Voyager 2 is currently in the constellation of Pavo, at a distance of 9.9 billion kilometres (about 12.4 billion miles) or 133 A.U from Earth. The current Right Ascension is 20h 08 m 36s and the Declination is -59° 13’ 56”.

Right now, from the United Kingdom, the spacecraft is not visible because it is below the horizon. You can check Voyager 2 Rise and Set Times to know when it will rise at your location.

How fast is Voyager 2 travelling?

Voyager 2 speed is approximately 55,470 km/h (or 34,390 miles per hour or 15 km/s) relative to the Sun. If it were in the atmosphere, it would fly around the Earth’s equator in 14 minutes. The ship has already passed all the large objects, so their gravity does not prevent it from developing a speed sufficient to leave the solar system.

In 2018, Voyager 2 reached the edge of the heliosphere, which extends twice as far as Pluto, but to break out of the Solar System, it needs to cross the Outer Limit of the Oort Cloud, which defines the hypothetical cosmographic boundary of the Solar System. According to scientists, this will take another 30,000 years. Incredibly long!

Has Voyager 2 lost contact?

On 21st July 2023, at a distance of 133 AU (19.9 billion km) from Earth, contact with the Voyager 2 probe was lost . The reason was an erroneous command sent to the Voyager computer, as a result of which it changed the orientation of the ship, and its antenna deviated from the line of communication with the Earth by two degrees. This was enough to stop the spacecraft from transmitting and receiving data.

Fortunately, just for such a case, the probe was programmed to “reset” its orientation data several times a year so that its antenna always remained directed towards the Earth. The next reset will take place on October 15th. But NASA decided not to risk it. They used a powerful radio telescope in the Australian capital, Canberra, to bombard the Voyager 2 area with messages containing the right command in the hope of regaining lost contact.

As a result, on 4th August, the space agency confirmed that the data from the spacecraft had been received and that it was working correctly.

Will Voyager 2 ever stop?

This can happen if the probe collides with another object or is pulled into the orbit of a celestial body by its gravity. But Voyager 2 travels in interstellar space, which is very rarefied, so scientists consider such a scenario unlikely. Even when a ship runs out of its energy sources and is no longer steerable, it will simply drift forever in desolate space.

Will Voyager 2 ever come back to Earth?

No, Voyager 2 will never return to Earth, primarily, because it was not built for a return. But even assuming NASA wants to bring the probe back, its engineers don’t have a plan for it. The probe is too far away from Earth and has lost too much power to make a thruster adjustment for the return course.

One can only hope that Voyager 2 fulfills its final mission — deliver a famous Golden Record , a message to any potential extraterrestrial civilizations. After all, there must be someone in this universe besides us.

Voyager 2 timeline

An amateur rocket enthusiast with a keen interest in all space-related activity. Looking forward to the day when the UK starts launching rockets into space and I'm able to watch launches (from a safe distance of course).

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A knotty problem: Boffins working on fuel-efficient trajectories for space travel

Not yet the london underground style efficient schematic we want, but it's a start.

Boffins at the UK's Surrey Space Centre have devised a way of determining the optimal route for spacecraft that doesn't require the engines to burn precious fuel.

The concept of shifting from one orbit to another without using fuel is not a new one. Engineers have turned to heteroclinic connections as a way of transferring a spacecraft between orbits without expending propellant. However, calculating these points presents a challenge, requiring either immense amounts of computing power or a human-in-the-loop to make an intelligent estimate that can be worked from.

In 2019, a paper was published, extolling the virtues of using artificial neural networks to identify heteroclinic connections.

The Voyager probes undertook the Grand Tour [PDF] based on a certain alignment of the planets that occurs once every 175 years. They used orbital mechanics and gravity assists to take in Jupiter, Saturn, and, in the case of Voyager 2, Uranus, and Neptune. However, the need to save fuel on missions closer to home has become a priority, thanks in part to NASA's Artemis program.

While a direct moonshot is all well and good, planners want to cut down on the fuel needed for expeditions around the vicinity of the Moon, particularly considering that a substantial chunk of the Artemis program involves the construction of the Lunar Gateway in orbit around the Moon. Hence the need for fuel-minimal trajectories in the vicinity of the Moon.

It's a variation of the classic three-body problem. One body is the spacecraft itself, while the other two are the Earth and the Moon. Yet calculating a trajectory to travel from point A to point B while using minimal fuel, thanks to heteroclinic connections, is no easy task.

The approach published by Postgraduate Research Student Danny Owen and Lecturer in Orbital Mechanics Dr Nicola Baresi this week uses knot theory , an area of mathematics. This is used to generate rough trajectories that can then be refined, effectively giving space agencies a variety of possible routes from a specific orbit.

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Owen said: "Previously, when the likes of NASA wanted to plot a route, their calculations relied on either brute force or guesswork.

"Our new technique neatly reveals all possible routes a spacecraft could take from A to B, as long as both orbits share a common energy level.

"This makes the task of planning missions much simpler. We think of it as a tube map for space."

The researchers have applied the technique to other planetary systems, including the Galilean moons of Jupiter, in addition to the Earth-Moon system. ®

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• Where Are They Now
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golden record

Where are they now.

• frequently asked questions
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Did You Know?

The Voyager mission was officially approved in May 1972. Through the dedicated efforts of many skilled personnel for over three decades, the Voyagers have returned knowledge about the outer planets that had not existed in all of the preceding history of astronomy and planetary science. The Voyager spacecrafts are still performing like champs.

It must come as no surprise that there are many remarkable, "gee-whiz" facts associated with the various aspects of the Voyager mission. These tidbits have been summarized below in appropriate categories. Several may seem difficult to believe, but they are all true and accurate.

Overall Mission

The total cost of the Voyager mission from May 1972 through the Neptune encounter (including launch vehicles, radioactive power source (RTGs), and DSN tracking support) is 865 million dollars. At first, this may sound very expensive, but the fantastic returns are a bargain when we place the costs in the proper perspective. It is important to realize that:

• on a per-capita basis, this is only 8 cents per U.S. resident per year, or roughly half the cost of one candy bar each year since project inception. the entire cost of Voyager is a fraction of the daily interest on the U.S. national debt.
• A total of 11,000 workyears was devoted to the Voyager project through the Neptune encounter. This is equivalent to one-third the amount of effort estimated to complete the great pyramid at Giza to King Cheops.

A total of five trillion bits of scientific data had been returned to Earth by both Voyager spacecraft at the completion of the Neptune encounter. This represents enough bits to fill more than seven thousand music CDs.

The sensitivity of our deep-space tracking antennas located around the world is truly amazing. The antennas must capture Voyager information from a signal so weak that the power striking the antenna is only 10 exponent -16 watts (1 part in 10 quadrillion). A modern-day electronic digital watch operates at a power level 20 billion times greater than this feeble level.

Voyager Spacecraft

Each Voyager spacecraft comprises 65,000 individual parts. Many of these parts have a large number of "equivalent" smaller parts such as transistors. One computer memory alone contains over one million equivalent electronic parts, with each spacecraft containing some five million equivalent parts. Since a color TV set contains about 2500 equivalent parts, each Voyager has the equivalent electronic circuit complexity of some 2000 color TV sets.

Like the HAL computer aboard the ship Discovery from the famous science fiction story 2001: A Space Odyssey, each Voyager is equipped with computer programming for autonomous fault protection. The Voyager system is one of the most sophisticated ever designed for a deep-space probe. There are seven top-level fault protection routines, each capable of covering a multitude of possible failures. The spacecraft can place itself in a safe state in a matter of only seconds or minutes, an ability that is critical for its survival when round-trip communication times for Earth stretch to several hours as the spacecraft journeys to the remote outer solar system.

Both Voyagers were specifically designed and protected to withstand the large radiation dosage during the Jupiter swing-by. This was accomplished by selecting radiation-hardened parts and by shielding very sensitive parts. An unprotected human passenger riding aboard Voyager 1 during its Jupiter encounter would have received a radiation dose equal to one thousand times the lethal level.

The Voyager spacecraft can point its scientific instruments on the scan platform to an accuracy of better than one-tenth of a degree. This is comparable to bowling strike-after-strike ad infinitum, assuming that you must hit within one inch of the strike pocket every time. Such precision is necessary to properly center the narrow-angle picture whose square field-of-view would be equivalent to the width of a bowling pin.

To avoid smearing in Voyager's television pictures, spacecraft angular rates must be extremely small to hold the cameras as steady as possible during the exposure time. Each spacecraft is so steady that angular rates are typically 15 times slower than the motion of a clock's hour hand. But even this was not steady enough at Neptune, where light levels are 900 times fainter than those on Earth. Spacecraft engineers devised ways to make Voyager 30 times steadier than the hour hand on a clock.

The electronics and heaters aboard each nearly one-ton Voyager spacecraft can operate on only 400 watts of power, or roughly one-fourth that used by an average residential home in the western United States.

A set of small thrusters provides Voyager with the capability for attitude control and trajectory correction. Each of these tiny assemblies has a thrust of only three ounces. In the absence of friction, on a level road, it would take nearly six hours to accelerate a large car up to a speed of 48 km/h (30 mph) using one of the thrusters.

The Voyager scan platform can be moved about two axes of rotation. A thumb-sized motor in the gear train drive assembly (which turns 9000 revolutions for each single revolution of the scan platform) will have rotated five million revolutions from launch through the Neptune encounter. This is equivalent to the number of automobile crankshaft revolutions during a trip of 2725 km (1700 mi), about the distance from Boston,MA to Dallas,TX.

The Voyager gyroscopes can detect spacecraft angular motion as little as one ten-thousandth of a degree. The Sun's apparent motion in our sky moves over 40 times that amount in just one second.

The tape recorder aboard each Voyager has been designed to record and playback a great deal of scientific data. The tape head should not begin to wear out until the tape has been moved back and forth through a distance comparable to that across the United States. Imagine playing a two-hour video cassette on your home VCR once a day for the next 33 years, without a failure.

The Voyager magnetometers are mounted on a frail, spindly, fiberglass boom that was unfurled from a two-foot-long can shortly after the spacecraft left Earth. After the boom telescoped and rotated out of the cannister to an extension of nearly 13 meters (43 feet), the orientations of the magnetometer sensors were controlled to an accuracy better than two degrees.

Each Voyager used the enormous gravity field of Jupiter to be hurled on to Saturn, experiencing a Sun-relative speed increase of roughly 35,700 mph. As total energy within the solar system must be conserved, Jupiter was initially slowed in its solar orbit---but by only one foot per trillion years. Additional gravity-assist swing-bys of Saturn and Uranus were necessary for Voyager 2 to complete its Grand Tour flight to Neptune, reducing the trip time by nearly twenty years when compared to the unassisted Earth-to-Neptune route.

The Voyager delivery accuracy at Neptune of 100 km (62 mi), divided by the trip distance or arc length traveled of 7,128,603,456 km (4,429,508,700 mi), is equivalent to the feat of sinking a 3630 km (2260 mi) golf putt, assuming that the golfer can make a few illegal fine adjustments while the ball is rolling across this incredibly long green.

Voyager's fuel efficiency (in terms of mpg) is quite impressive. Even though most of the launch vehicle's 700 ton weight is due to rocket fuel, Voyager 2's great travel distance of 7.1 billion km (4.4 billion mi) from launch to Neptune resultsed in a fuel economy of about 13,000 km per liter (30,000 mi per gallon). As Voyager 2 streaked by Neptune and coasts out of the solar system, this fuel economy just got better and better!

The resolution of the Voyager narrow-angle television cameras is sharp enough to read a newspaper headline at a distance of 1 km (0.62 mi).

Pele, the largest of the volcanoes seen on Jupiter's moon Io, is throwing sulfur and sulfur-dioxide products to heights 30 times that of Mount Everest, and the fallout zone covers an area the size of France. The eruption of Mount St. Helens was but a tiny hiccup in comparison (admittedly, Io's surface-level gravity is some six times weaker than that of Earth).

The smooth water-ice surface of Jupiter's moon Europa may hide an ocean beneath, but some scientists believe any past oceans have turned to slush or ice. In 2010: Odyssey Two, Arthur C. Clarke wraps his story around the possibility of life developing within the oceans of Europa.

The rings of Saturn appeared to the Voyagers as a dazzling necklace of 10,000 strands. Trillions of ice particles and car-sized bergs race along each of the million-kilometer-long tracks, with the traffic flow orchestrated by the combined gravitational tugs of Saturn, a retinue of moons and moonlets, and even nearby ring particles. The rings of Saturn are so thin in proportion to their 171,000 km (106,000 mi) width that, if a full-scale model were to be built with the thickness of a phonograph record the model would have to measure four miles from its inner edge to its outer rim. An intricate tapestry of ring-particle patterns is created by many complex dynamic interactions that have spawned new theories of wave and particle motion.

Saturn's largest moon Titan was seen as a strange world with its dense atmosphere and variety of hydrocarbons that slowly fall upon seas of ethane and methane. To some scientists, Titan, with its principally nitrogen atmosphere, seemed like a small Earth whose evolution had long ago been halted by the arrival of its ice age, perhaps deep-freezing a few organic relics beneath its present surface.

The rings of Uranus are so dark that Voyager's challenge of taking their picture was comparable to the task of photographing a pile of charcoal briquettes at the foot of a Christmas tree, illuminated only by a 1 watt bulb at the top of the tree, using ASA-64 film. And Neptune light levels will be less than half those at Uranus.

Through the ages, astronomers have argued without agreeing on where the solar system ends. One opinion is that the boundary is where the Sun’s gravity no longer dominates – a point beyond the planets and beyond the Oort Cloud. This boundary is roughly about halfway to the nearest star, Proxima Centauri. Traveling at speeds of over 35,000 miles per hour, it will take the Voyagers nearly 40,000 years, and they will have traveled a distance of about two light years to reach this rather indistinct boundary.

But there is a more definitive and unambiguous frontier, which the Voyagers will approach and pass through. This is the heliopause, which is the boundary area between the solar and the interstellar wind. When Voyager 1 crosses the solar wind termination shock, it will have entered into the heliosheath, the turbulent region leading up to the heliopause. When the Voyagers cross the heliopause, hopefully while the spacecraft are still able to send science data to Earth, they will be in interstellar space even though they will still be a very long way from the “edge of the solar system”. Once Voyager is in interstellar space, it will be immersed in matter that came from explosions of nearby stars. So, in a sense, one could consider the heliopause as the final frontier.

Barring any serious spacecraft subsystem failures, the Voyagers may survive until the early twenty-first century (~ 2025), when diminishing power and hydrazine levels will prevent further operation. Were it not for these dwindling consumables and the possibility of losing lock on the faint Sun, our tracking antennas could continue to "talk" with the Voyagers for another century or two!