Category: voyager

Solar System: 10 Things to Know This Week

Pioneer Days

Someone’s got to be first. In space, the first explorers beyond Mars were Pioneers 10 and 11, twin robots who charted the course to the cosmos.


1-Before Voyager


Voyager, with its outer solar system tour and interstellar observations, is often credited as the greatest robotic space mission. But today we remember the plucky Pioneers, the spacecraft that proved Voyager’s epic mission was possible.

2-Where No One Had Gone Before


Forty-five years ago this week, scientists still weren’t sure how hard it would be to navigate the main asteroid belt, a massive field of rocky debris between Mars and Jupiter. Pioneer 10 helped them work that out, emerging from first the first six-month crossing in February 1973. Pioneer 10 logged a few meteoroid hits (fewer than expected) and taught engineers new tricks for navigating farther and farther beyond Earth.

3-Trailblazer No. 2


Pioneer 11 was a backup spacecraft launched in 1973 after Pioneer 10 cleared the asteroid belt. The new mission provided a second close look at Jupiter, the first close-up views of Saturn and also gave Voyager engineers plotting an epic multi-planet tour of the outer planets a chance to practice the art of interplanetary navigation.

4-First to Jupiter


Three-hundred and sixty-three years after humankind first looked at Jupiter through a telescope, Pioneer 10 became the first human-made visitor to the Jovian system in December 1973. The spacecraft spacecraft snapped about 300 photos during a flyby that brought it within 81,000 miles (about 130,000 kilometers) of the giant planet’s cloud tops.

5-Pioneer Family


Pioneer began as a Moon program in the 1950s and evolved into increasingly more complicated spacecraft, including a Pioneer Venus mission that delivered a series of probes to explore deep into the mysterious toxic clouds of Venus. A family portrait (above) showing (from left to right) Pioneers 6-9, 10 and 11 and the Pioneer Venus Orbiter and Multiprobe series. Image date: March 11, 1982. 

6-A Pioneer and a Pioneer


Classic rock has Van Halen, we have Van Allen. With credits from Explorer 1 to Pioneer 11, James Van Allen was a rock star in the emerging world of planetary exploration. Van Allen (1914-2006) is credited with the first scientific discovery in outer space and was a fixture in the Pioneer program. Van Allen was a key part of the team from the early attempts to explore the Moon (he’s pictured here with Pioneer 4) to the more evolved science platforms aboard Pioneers 10 and 11.

7-The Farthest…For a While


For more than 25 years, Pioneer 10 was the most distant human-made object, breaking records by crossing the asteroid belt, the orbit of Jupiter and eventually even the orbit of Pluto. Voyager 1, moving even faster, claimed the most distant title in February 1998 and still holds that crown.

8-Last Contact


We last heard from Pioneer 10 on Jan. 23, 2003. Engineers felt its power source was depleted and no further contact should be expected. We tried again in 2006, but had no luck. The last transmission from Pioneer 11 was received in September 1995. Both missions were planned to last about two years.

9-Galactic Ghost Ships


Pioneers 10 and 11 are two of five spacecraft with sufficient velocity to escape our solar system and travel into interstellar space. The other three—Voyagers 1 and 2 and New Horizons—are still actively talking to Earth. The twin Pioneers are now silent. Pioneer 10 is heading generally for the red star Aldebaran, which forms the eye of Taurus (The Bull). It will take Pioneer over 2 million years to reach it. Pioneer 11 is headed toward the constellation of Aquila (The Eagle) and will pass nearby in about 4 million years.

10-The Original Message to the Cosmos


Years before Voyager’s famed Golden Record, Pioneers 10 and 11 carried the original message from Earth to the cosmos. Like Voyager’s record, the Pioneer plaque was the brainchild of Carl Sagan who wanted any alien civilization who might encounter the craft to know who made it and how to contact them. The plaques give our location in the galaxy and depicts a man and woman drawn in relation to the spacecraft.

Read the full version of this week’s 10 Things article HERE

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Voyager 1’s thrusters fired up for first time …

Voyager 1’s thrusters fired up for first time since 1980:

The venerable Voyager 1 spacecraft.  Still impressing after all these years. 

Spooky Sounds from Across the Solar System

Soaring to the depths of our universe, gallant spacecraft roam the cosmos, snapping images of celestial wonders. Some spacecraft have instruments capable of capturing radio emissions. When scientists convert these to sound waves, the results are eerie to hear.

In time for Halloween, we’ve put together a compilation of elusive “sounds” of howling planets and whistling helium that is sure to make your skin crawl.

Listen to a few here and visit our Soundcloud for more spooky sounds. 

Cassini Ring Crossing

This eerie audio represents data collected by our Cassini spacecraft, as it crossed through the gap between Saturn and its rings on April 26, 2017, during the first dive of the mission’s Grand Finale. The instrument is able to record ring particles striking the spacecraft in its data. In the data from this dive, there is virtually no detectable peak in pops and cracks that represent ring particles striking the spacecraft. The lack of discernible pops and cracks indicates the region is largely free of small particles. 

Voyager Tsunami Waves in Interstellar Space 

Listen to this howling audio from our Voyager 1 spacecraft. Voyager 1 has experienced three “tsunami waves” in interstellar space. This kind of wave occurs as a result of a coronal mass ejection erupting from the Sun. The most recent tsunami wave that Voyager experienced began in February 2014, and may still be going. Listen to how these waves cause surrounding ionized matter to ring like a bell.

Voyager Sounds of Interstellar Space

Our Voyager 1 spacecraft captured these high-pitched, spooky sounds of interstellar space from October to November 2012 and April to May 2013.

The soundtrack reproduces the amplitude and frequency of the plasma waves as “heard” by Voyager 1. The waves detected by the instrument antennas can be simply amplified and played through a speaker. These frequencies are within the range heard by human ears.

When scientists extrapolated this line even further back in time (not shown), they deduced that Voyager 1 first encountered interstellar plasma in August 2012.

Plasma Sounds at Jupiter

Ominous sounds of plasma! Our Juno spacecraft has observed plasma wave signals from Jupiter’s ionosphere. The results in this video show an increasing plasma density as Juno descended into Jupiter’s ionosphere during its close pass by Jupiter on February 2, 2017.  

Roar of Jupiter

Juno’s Waves instrument recorded this supernatural sounding encounter with the bow shock over the course of about two hours on June 24, 2016. “Bow shock” is where the supersonic solar wind is heated and slowed by Jupiter’s magnetosphere. It is analogous to a sonic boom on Earth. The next day, June 25, 2016, the Waves instrument witnessed the crossing of the magnetopause. “Trapped continuum radiation” refers to waves trapped in a low-density cavity in Jupiter’s magnetosphere.

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Thanks to the twin Voyager spacecraft, music is truly universal:…

Thanks to the twin Voyager spacecraft, music is truly universal: Each carries a Golden Record with sights, sounds and songs from Earth as it sails on through the Milky Way. Recalling the classic rock era of the late 1970s when the Voyagers launched, this poster is an homage to the mission’s greatest hits. Some of the most extraordinary discoveries of the probes’ first 40 years include the volcanoes on Jupiter’s moon Io, the hazy nitrogen atmosphere of Saturn’s moon Titan and the cold geysers on Neptune’s moon Triton. Voyager 1 is also the first spacecraft to deliver a portrait of our planets from beyond Neptune, depicting Earth as a ‘pale blue dot,’ as of Aug. 25, 2012, to enter interstellar space. Voyager 2 is expected to enter interstellar space in the coming years. Even after 40 years, the Voyagers’ hits just keep on coming.  

Enjoy this and other Voyager anniversary posters. Download them for free here:

Credit: NASA/JPL-Caltech

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The twin Voyager spacecraft, which launched in 1977, are our…

The twin Voyager spacecraft, which launched in 1977, are our ambassadors to the rest of the Milky Way, destined to continue orbiting the center of our galaxy for billions of years after they stop communicating with Earth. On Aug. 25, 2012, Voyager 1 became the first human-made object to enter interstellar space, and Voyager 2 is expected to cross over in the next few years. At age 40, the Voyagers are the farthest and longest-operating spacecraft and still have plenty more to discover. This poster captures the spirit of exploration, the vastness of space and the wonder that has fueled this ambitious journey to the outer planets and beyond.

Enjoy this and other Voyager anniversary posters. Download them for free here:

Credit: NASA/JPL-Caltech

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Voyager: The Space Between

Our Voyager 1 spacecraft officially became the first human-made object to venture into interstellar space in 2012. 


Whether and when our Voyager 1 spacecraft broke through to interstellar space, the space between stars, has been a thorny issue. 

In 2012, claims surfaced every few months that Voyager 1 had “left our solar system.” Why had the Voyager team held off from saying the craft reached interstellar space until 2013?


Basically, the team needed more data on plasma, which is an ionozied gas that exists throughout space. (The glob of neon in a storefront sign is an example of plasma).


Plasma is the most important marker that distinguishes whether Voyager 1 is inside the solar bubble, known as the heliosphere.  The heliosphere is defined by the constant stream of plasma that flows outward from our Sun – until it meets the boundary of interstellar space, which contains plasma from other sources.


Adding to the challenge: they didn’t know how they’d be able to detect it.

No one has been to interstellar space before, so it’s  like traveling with guidebooks that are incomplete.

Additionally, Voyager 1’s plasma instrument, which measures the density, temperature and speed of plasma, stopped working in 1980, right after its last planetary flyby.


When Voyager 1 detected the pressure of interstellar space on our heliosphere in 2004, the science team didn’t have the instrument that would provide the most direct measurements of plasma. 

Voyager 1 Trajectory

Instead, they focused on the direction of the magnetic field as a proxy for source of the plasma. Since solar plasma carries the magnetic field lines emanating from the Sun and interstellar plasma carries interstellar magnetic field lines, the directions of the solar and interstellar magnetic fields were expected to differ.

Voyager 2 Trajectory

In May 2012, the number of galactic cosmic rays made its first significant jump, while some of the inside particles made their first significant dip. The pace of change quickened dramatically on July 28, 2012. After five days, the intensities returned to what they had been. This was the first taste test of a new region, and at the time Voyager scientists thought the spacecraft might have briefly touched the edge of interstellar space.


By Aug. 25, when, as we now know, Voyager 1 entered this new region for good, all the lower-energy particles from inside zipped away. Some inside particles dropped by more than a factor of 1,000 compared to 2004. However, subsequent analysis of the magnetic field data revealed that even though the magnetic field strength jumped by 60% at the boundary, the direction changed less than 2 degrees. This suggested that Voyager 1 had not left the solar magnetic field and had only entered a new region, still inside our solar bubble, that had been depleted of inside particles.


Then, in April 2013, scientists got another piece of the puzzle by chance. For the first eight years of exploring the heliosheath, which is the outer layer of the heliosphere, Voyager’s plasma wave instrument had heard nothing. But the plasma wave science team had observed bursts of radio waves in 1983 and 1984 and again in 1992 and 1993. They determined these bursts were produced by the interstellar plasma when a large outburst of solar material would plow into it and cause it to oscillate.


It took about 400 days for such solar outbursts to reach interstellar space, leading to an estimated distance of 117 to 177 AU (117 to 177 times the distance from the Sun to the Earth) to the heliopause.

Then on April 9, 2013, it happened: Voyager 1’s plasma wave instrument picked up local plasma oscillations. Scientists think they probably stemmed from a burst of solar activity from a year before. The oscillations increased in pitch through May 22 and indicated that Voyager was moving into an increasingly dense region of plasma.

The above soundtrack reproduces the amplitude and frequency of the plasma waves as “heard” by Voyager 1. The waves detected by the instrument antennas can be simply amplified and played through a speaker. These frequencies are within the range heard by human ears.


When they extrapolated back, they deduced that Voyager had first encountered this dense interstellar plasma in Aug. 2012, consistent with the sharp boundaries in the charged particle and magnetic field data on Aug. 25.

In the end, there was general agreement that Voyager 1 was indeed outside in interstellar space, but that location comes with some disclaimers. They determined the spacecraft is in a mixed transitional region of interstellar space. We don’t know when it will reach interstellar space free from the influence of our solar bubble.


Voyager 1, which is working with a finite power supply, has enough electrical power to keep operating the fields and particles science instruments through at least 2020, which will make 43 years of continual operation.


Voyager 1 will continue sending engineering data for a few more years after the last science instrument is turned off, but after that it will be sailing on as a silent ambassador. 

In about 40,000 years, it will be closer to the star AC +79 3888 than our own Sun.

And for the rest of time, Voyager 1 will continue orbiting around the heart of the Milky Way galaxy, with our Sun but a tiny point of light among many.

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Planets: As Seen by Voyager

The Voyager 1 and 2 spacecraft explored Jupiter, Saturn, Uranus and Neptune before starting their journey toward interstellar space. Here you’ll find some of those images, including “The Pale Blue Dot” – famously described by Carl Sagan – and what are still the only up-close images of Uranus and Neptune.

These twin spacecraft took some of the very first close-up images of these planets and paved the way for future planetary missions to return, like the Juno spacecraft at Jupiter, Cassini at Saturn and New Horizons at Pluto.



Photography of Jupiter began in January 1979, when images of the brightly banded planet already exceeded the best taken from Earth. They took more than 33,000 pictures of Jupiter and its five major satellites. 



  • Erupting volcanoes on Jupiter’s moon Io, which has 100 times the volcanic activity of Earth. 
  • Better understanding of important physical, geological, and atmospheric processes happening in the planet, its satellites and magnetosphere.
  • Jupiter’s turbulent atmosphere with dozens of interacting hurricane-like storm systems.



The Saturn encounters occurred nine months apart, in November 1980 and August 1981. The two encounters increased our knowledge and altered our understanding of Saturn. The extended, close-range observations provided high-resolution data far different from the picture assembled during centuries of Earth-based studies.



  • Saturn’s atmosphere is almost entirely hydrogen and helium.
  • Subdued contrasts and color differences on Saturn could be a result of more horizontal mixing or less production of localized colors than in Jupiter’s atmosphere.
  • An indication of an ocean beneath the cracked, icy crust of Jupiter’s moon Europa. 
  • Winds blow at high speeds in Saturn. Near the equator, the Voyagers measured winds about 1,100 miles an hour.


The Voyager 2 spacecraft flew closely past distant Uranus, the seventh planet from the Sun. At its closest, the spacecraft came within 50,600 miles of Uranus’s cloud tops on Jan. 24, 1986. Voyager 2 radioed thousands of images and voluminous amounts of other scientific data on the planet, its moons, rings, atmosphere, interior and the magnetic environment surrounding Uranus.



  • Revealed complex surfaces indicative of varying geologic pasts.
  • Detected 11 previously unseen moons.
  • Uncovered the fine detail of the previously known rings and two newly detected rings.
  • Showed that the planet’s rate of rotation is 17 hours, 14 minutes.
  • Found that the planet’s magnetic field is both large and unusual.
  • Determined that the temperature of the equatorial region, which receives less sunlight over a Uranian year, is nevertheless about the same as that at the poles.


Voyager 2 became the first spacecraft to observe the planet Neptune in the summer of 1989. Passing about 3,000 miles above Neptune’s north pole, Voyager 2 made its closest approach to any planet since leaving Earth 12 years ago. Five hours later, Voyager 2 passed about 25,000 miles from Neptune’s largest moon, Triton, the last solid body the spacecraft had the opportunity to study.



  • Discovered Neptune’s Great Dark Spot
  • Found that the planet has strong winds, around 1,000 miles per hour
  • Saw geysers erupting from the polar cap on Neptune’s moon Triton at -390 degrees Fahrenheit

Solar System Portrait

This narrow-angle color image of the Earth, dubbed ‘Pale Blue Dot’, is a part of the first ever ‘portrait’ of the solar system taken by Voyager 1. 


The spacecraft acquired a total of 60 frames for a mosaic of the solar system from a distance of more than 4 billion miles from Earth and about 32 degrees above the ecliptic.


From Voyager’s great distance, Earth is a mere point of light, less than the size of a picture element even in the narrow-angle camera.


“Look again at that dot. That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives.” – Carl Sagan

Both spacecraft will continue to study ultraviolet sources among the stars, and their fields and particles detectors will continue to search for the boundary between the Sun’s influence and interstellar space. The radioisotope power systems will likely provide enough power for science to continue through 2025, and possibly support engineering data return through the mid-2030s. After that, the two Voyagers will continue to orbit the center of the Milky Way.

Learn more about the Voyager spacecraft HERE.

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Voyager: The Golden Record

It’s the 1970s, and we’re about to send two spacecraft (Voyager 1 & 2) into space. These two spacecraft will eventually leave our solar system and become the most distant man-made objects…ever. How can we leave our mark on them in the case that other spacefarers find them in the distant future?

The Golden Record.


We placed an ambitious message aboard Voyager 1 and 2, a kind of time capsule, intended to communicate a story of our world to extraterrestrials. The Voyager message is carried by a phonograph record, a 12-inch gold-plated copper disk containing sounds and images selected to portray the diversity of life and culture on Earth.

The Golden Record Cover

The outward facing cover of the golden record carries instructions in case it is ever found. Detailing to its discoverers how to decipher its meaning.

In the upper left-hand corner is an easily recognized drawing of the phonograph record and the stylus carried with it. The stylus is in the correct position to play the record from the beginning. Written around it in binary arithmetic is the correct time of one rotation of the record. The drawing indicates that the record should be played from the outside in.


The information in the upper right-hand portion of the cover is designed to show how the pictures contained on the record are to be constructed from the recorded signals. The top drawing shows the typical signal that occurs at the start of the picture. The picture is made from this signal, which traces the picture as a series of vertical lines, similar to ordinary television. Immediately below shows how these lines are to be drawn vertically, with staggered “interlace” to give the correct picture rendition. Below that is a drawing of an entire picture raster, showing that there are 52 vertical lines in a complete picture.


Immediately below this is a replica of the first picture on the record to permit the recipients to verify that they are decoding the signals correctly. A circle was used in this picture to ensure that the recipients use the correct ratio of horizontal to vertical height in picture reconstruction.


The drawing in the lower left-hand corner of the cover is the pulsar map previously sent as part of the plaques on Pioneers 10 and 11. It shows the location of the solar system with respect to 14 pulsars, whose precise periods are given.


The drawing containing two circles in the lower right-hand corner is a drawing of the hydrogen atom in its two lowest states, with a connecting line and digit 1 to indicate that the time interval associated with the transition from one state to the other is to be used as the fundamental time scale, both for the time given on the cover and in the decoded pictures.

The Contents

The contents of the record were selected for NASA by a committee chaired by Carl Sagan of Cornell University and his associates. 


They assembled 115 images and a variety of natural sounds, such as those made by surf, wind and thunder, birds, whales and other animals. To this, they added musical selections from different cultures and eras, and spoken greetings from Earth-people in fifty-five languages, and printed messages from President Carter and U.N. Secretary General Waldheim.


Listen to some of the sounds of the Golden Record on our Soundcloud page:


Songs from Chuck Berry’s “Johnny B. Goode,” to Beethoven’s Fifth Symphony are included on the golden record. For a complete list of songs, visit:


The 115 images included on the record, encoded in analog form, range from mathematical definitions to humans from around the globe. See the images here:

Making the Golden Record

Many people were instrumental in the design, development and manufacturing of the golden record. 


Blank records were provided by the Pyral S.A. of Creteil, France. CBS Records contracted the JVC Cutting Center in Boulder, CO to cut the lacquer masters which were then sent to the James G. Lee Record Processing center in Gardena, CA to cut and gold plate eight Voyager records.


The record is constructed of gold-plated copper and is 12 inches in diameter. The record’s cover is aluminum and electroplated upon it is an ultra-pure sample of the isotope uranium-238. Uranium-238 has a half-life of 4.468 billion years.

Learn more about the golden record HERE.

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Voyager: The Spacecraft

The twin Voyager 1 and 2 spacecraft are exploring where nothing from Earth has flown before. Continuing their more-than-40-year journey since their 1977 launches, they each are much farther away from Earth and the Sun than Pluto.


The primary mission was the exploration of Jupiter and Saturn. After making a string of discoveries there – such as active volcanoes on Jupiter’s moon Io and intricacies of Saturn’s rings – the mission was extended. 


Voyager 2 went on to explore Uranus and Neptune, and is still the only spacecraft to have visited those outer planets. The adventurers’ current mission, the Voyager Interstellar Mission (VIM), will explore the outermost edge of the Sun’s domain. And beyond.

Spacecraft Instruments

‘BUS’ Housing Electronics


The basic structure of the spacecraft is called the “bus,” which carries the various engineering subsystems and scientific instruments. It is like a large ten-sided box. Each of the ten sides of the bus contains a compartment (a bay) that houses various electronic assemblies.

Cosmic Ray Subsystem (CRS)

The Cosmic Ray Subsystem (CRS) looks only for very energetic particles in plasma, and has the highest sensitivity of the three particle detectors on the spacecraft. Very energetic particles can often be found in the intense radiation fields surrounding some planets (like Jupiter). Particles with the highest-known energies come from other stars. The CRS looks for both.

High-Gain Antenna (HGA)


The High-Gain Antenna (HGA) transmits data to Earth on two frequency channels (the downlink). One at about 8.4 gigahertz, is the X-band channel and contains science and engineering data. For comparison, the FM radio band is centered around 100 megahertz.

Imaging Science Subsystem (ISS)


The Imaging Science Subsystem (ISS) is a modified version of the slow scan vidicon camera designed that were used in the earlier Mariner flights. The ISS consists of two television-type cameras, each with eight filters in a commandable Filter Wheel mounted in front of the vidicons. One has a low resolution 200 mm wide-angle lens, while the other uses a higher resolution 1500 mm narrow-angle lens.

Infrared Interferometer Spectrometer and Radiometer (IRIS)

The Infrared Interferometer Spectrometer and Radiometer (IRIS) actually acts as three separate instruments. First, it is a very sophisticated thermometer. It can determine the distribution of heat energy a body is emitting, allowing scientists to determine the temperature of that body or substance.

Second, the IRIS is a device that can determine when certain types of elements or compounds are present in an atmosphere or on a surface.

Third, it uses a separate radiometer to measure the total amount of sunlight reflected by a body at ultraviolet, visible and infrared frequencies.

Low-Energy Charged Particles (LECP)


The Low-Energy Charged Particles (LECP) looks for particles of higher energy than the Plasma Science instrument, and it overlaps with the Cosmic Ray Subsystem (CRS). It has the broadest energy range of the three sets of particle sensors. 

The LECP can be imagined as a piece of wood, with the particles of interest playing the role of the bullets. The faster a bullet moves, the deeper it will penetrate the wood. Thus, the depth of penetration measures the speed of the particles. The number of “bullet holes” over time indicates how many particles there are in various places in the solar wind, and at the various outer planets. The orientation of the wood indicates the direction from which the particles came.

Magnetometer (MAG)


Although the Magnetometer (MAG) can detect some of the effects of the solar wind on the outer planets and moons, its primary job is to measure changes in the Sun’s magnetic field with distance and time, to determine if each of the outer planets has a magnetic field, and how the moons and rings of the outer planets interact with those magnetic fields.

Optical Calibration Target
The target plate is a flat rectangle of known color and brightness, fixed to the spacecraft so the instruments on the movable scan platform (cameras, infrared instrument, etc.) can point to a predictable target for calibration purposes.

Photopolarimeter Subsystem (PPS)

The Photopolarimeter Subsystem (PPS) uses a 0.2 m telescope fitted with filters and polarization analyzers. The experiment is designed to determine the physical properties of particulate matter in the atmospheres of Jupiter, Saturn and the rings of Saturn by measuring the intensity and linear polarization of scattered sunlight at eight wavelengths. 

The experiment also provided information on the texture and probable composition of the surfaces of the satellites of Jupiter and Saturn.

Planetary Radio Astronomy (PRA) and Plasma Wave Subsystem (PWS)

Two separate experiments, The Plasma Wave Subsystem and the Planetary Radio Astronomy experiment, share the two long antennas which stretch at right-angles to one another, forming a “V”.

Plasma Science (PLS)

The Plasma Science (PLS) instrument looks for the lowest-energy particles in plasma. It also has the ability to look for particles moving at particular speeds and, to a limited extent, to determine the direction from which they come. 

The Plasma Subsystem studies the properties of very hot ionized gases that exist in interplanetary regions. One plasma detector points in the direction of the Earth and the other points at a right angle to the first.

Radioisotope Thermoelectric Generators (RTG)


Three RTG units, electrically parallel-connected, are the central power sources for the mission module. The RTGs are mounted in tandem (end-to-end) on a deployable boom. The heat source radioisotopic fuel is Plutonium-238 in the form of the oxide Pu02. In the isotopic decay process, alpha particles are released which bombard the inner surface of the container. The energy released is converted to heat and is the source of heat to the thermoelectric converter.

Ultraviolet Spectrometer (UVS)

The Ultraviolet Spectrometer (UVS) is a very specialized type of light meter that is sensitive to ultraviolet light. It determines when certain atoms or ions are present, or when certain physical processes are going on. 

The instrument looks for specific colors of ultraviolet light that certain elements and compounds are known to emit.

Learn more about the Voyager 1 and 2 spacecraft HERE.

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Solar System: Things to Know This Week

Almost every day, we receive a message from a spacecraft more than 10.6 billion miles (about 17 billion km) away.

At that unimaginable distance, it takes the radio signal almost 16 hours to arrive. The spacecraft is Voyager 2, which launched 40 years ago this month. It’s still operating, sending back dispatches from the dark reaches well beyond the orbit of Pluto. Even now, scientists are still actively exploring the outer boundaries of the solar system using Voyager 2, decades after its “Grand Tour” of the giant planets Jupiter, Saturn, Uranus and Neptune revealed their splendors like never before. This week, we recall 10 highlights from one of the most epic voyages in human history.

1. A Journey of 10 Billion Miles Begins With the First Step


Voyager 2 set out from Earth on Aug. 20, 1977. Even though it launched before its twin spacecraft, Voyager 1, it carried the ‘2’ moniker because mission planners knew its trajectory would bring it to Jupiter after Voyager 1’s arrival there.

2. The Grand Tour

Voyager 2’s trajectory was special because it took advantage of a rare orbital alignment to fly by all four gas giant planets: Jupiter, Saturn, Uranus and Neptune. It was the first, and so far the only, spacecraft to carry out a close-up reconnaissance of Uranus and Neptune.

3. Not-So-Gentle Giant

Voyager 2 flew by Jupiter in April 1979, capturing striking images of the planet’s volcanic moon Io and its violent storms larger than the entire Earth.

4. Saturn’s Not the Only One


Jupiter has its own ring system, and Voyager 2 provided the first pictures.

5. An Ocean Under Ice

During its Jupiter encounter, Voyager 2 obtained close-up looks at Jupiter’s moon Europa, including linear cracks and other features which first led scientists to realize Europa probably hides a vast sea of liquid water beneath an icy shell, the first known world outside Earth that could have an ocean.

6. Ringworld, the Prequel

Voyager 2 zoomed through the Saturn system in August 1981. It saw hints of mysterious features that the Cassini mission would later reveal in stunning detail, including Enceladus, with its bright surface that suggested geologic activity, and Saturn’s intriguing hexagonal jet stream.

7. Swiftly by a Tilted Planet

In January 1984, Voyager offered humanity its first detailed look at the seventh planet, Uranus, the only one tilted on its side relative to the Sun. Voyager images revealed 11 new moons, including Juliet, Puck, Cressida, Rosalind and Ophelia. The moon Miranda presented a bizarre landscape that left scientists debating its origins for years. Voyager also captured views of the planet’s lacy rings, and found that it is the coldest in the solar system, at minus 353 degrees Fahrenheit (59 Kelvin).

8. In Neptune’s Blue Realm


After picking up a gravitational speed boost at each previous planetary encounter, by the time Voyager reached Neptune it shot through the entire system of Neptunian rings and moons in a matter of hours. Voyager saw a titanic storm in Neptune’s windy atmosphere, discovered new moons, and revealed active geysers erupting on Triton’s frigid surface.

9. Postcards From the Edge

Although their cameras are no longer functioning, other key scientific instruments on board both Voyager spacecraft are still collecting data. Voyager 1 is exploring the boundary between the Sun’s realm and interstellar space. Voyager 2 hasn’t traveled quite as far. In September 2007, it crossed the termination shock (where the speed of the solar wind of charged particles drops below the speed of sound) at a point about 84 Astronomical Units from the Sun (more than twice the distance to Pluto). See

10. Ride Along

Voyager’s mission is far from over. Engineers estimate the spacecraft will have enough power to operate into the mid-2020s. You can ride along at, or by following @NASAVoyager on Twitter and by downloading our free 3-D space simulation software, Eyes on the Solar System at


One more thing: Inspired by the messages of goodwill carried on Voyager’s Golden Record, you’re invited to send a short, uplifting message to Voyager and all that lies beyond it via social media. With input from the Voyager team and a public vote, one of these messages will be selected for us to beam into interstellar space on Sept. 5, 2017—the 40th anniversary of Voyager 1’s launch. Post your message on social media with the tag #MessageToVoyager by Aug 15. Details:

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