Artykuły o The Voyagers' Odyssey

[Orionid]

Voyager 2 Spacecraft Enters Interstellar Space
After a journey of more than four decades, Voyager 2 has passed beyond the sun’s influence
By Jonathan O'Callaghan on December 10, 2018


This illustration shows the position of NASA’s Voyager 1 and Voyager 2 probes beyond the heliosphere, a region of space dominated by our sun that extends well past the orbit of Pluto. Credit: JPL-Caltech and NASA

NASA’s Voyager 2 spacecraft has crossed into interstellar space, agency officials announced today.

The milestone makes Voyager 2 humanity’s second operating spacecraft in history to go interstellar after the Voyager 1 spacecraft did in August 2012. “One kind of feels like a lucky fluke,” says Justin Kasper, a scientist involved in the Voyager missions from the University of Michigan in Ann Arbor. “Two feels like we’re becoming a society that’s capable of exploring interstellar space.”

Voyager 2’s new interstellar status is based on data from its Plasma Science Experiment (PLS), which logged a decrease in particles around the spacecraft that had been ejected from our sun. The PLS measurements of this “solar wind” plummeted to zero on November 5—the official date of Voyager 2’s departure. Now the mission team is confident the spacecraft has joined its predecessor in passing beyond a key boundary called the heliopause and into interstellar space. “November 5 was the day that the galactic cosmic-ray intensity abruptly increased, and that same date was when the heliospheric particle intensity dropped significantly,” says Voyager project scientist Ed Stone. “That same day the magnetic field increased, and that’s also the point at which the plasma [instrument] quit measuring the solar wind. So that’s the correlation we were looking at [to confirm interstellar space].”

The heliopause is the region at which the solar wind’s outward expansion is countered by the influence of incoming interstellar particles. It is considered to be one of the limits of the sun’s influence on surrounding space—although the two spacecraft are still said to be inside the solar system, they are now in a region of space dominated more by the Milky Way Galaxy than our sun. Prior to this, Voyager 2 crossed a region known as the termination shock back in 2007, where the speed of the solar wind dropped dramatically as it began to encounter interstellar particles and radiation. The entire region of the sun’s bubble of influence in the galaxy is known as the heliosphere, whereas the region Voyager 2 has just traversed is called the heliosheath, which lies between the termination shock and the heliopause.

NASA launched the twin Voyager spacecraft in 1977 on a mission to explore the outer planets. After both studying Jupiter and Saturn—with Voyager 2 taking a detour to also visit Uranus and Neptune—the two probes continued their journeys toward the edge of the solar system. In August 2012 Voyager 1 became the first human-made vehicle in history to reach the heliopause and enter interstellar space. But both missions have raised questions about our solar system’s true boundary. Originally some scientists speculated our star’s winds would peter out in the vicinity of Mars, but the Voyager spacecraft have gradually pushed this boundary far beyond. The solar system’s actual limit remains contentious, however, with some researchers defining it not by solar winds but rather by the most distant objects thought to be held in thrall by our sun’s gravity—comets in the Oort Cloud up to about two light-years away. Regardless of where one believes the sun’s sphere of influence ends, both Voyagers are poised to greatly extend it—each has a famous Golden Record onboard in the event any other spacefaring species happens across them on their lonely, eons-long sojourns between the stars.

Voyager 2 has traveled about 120 astronomical units—one AU is the Earth–sun distance—which equates to just over 18 billion kilometers, a distance light itself takes more than 16 hours to traverse. Although far out, this is about one AU closer in than Voyager 1’s earlier exit from the solar system. The most obvious explanation for this disparity is that our solar system’s heliosphere is not perfectly spherical—instead it is oddly shaped and asymmetric, perhaps due to the influence of the Milky Way’s magnetic field. “You can think of the galactic magnetic field as an array of bungee cords,” says Eric Christian from NASA Goddard Space Flight Center, a scientist on the Voyager team. “The solar system is this soccer ball you’re pushing through these bungee cords,” flexing and distorting its shape as it moves.

Another possible explanation is the sun’s fluctuating activity, measured via outbursts such as solar flares and powerful explosions called coronal mass ejections. These events can affect the heliosphere much like gas pumped into a balloon, causing it to grow—conversely, when their numbers decrease the heliosphere can shrink, changing the location of the heliopause. It is possible that in coming years, as the sun reaches the peak of its roughly 11-year activity cycle, its outbursts could push the heliopause farther out again, perhaps even beyond Voyager 2. “There’s a chance [the probe could enter interstellar space twice],” Kasper says. “It’s all going to depend on how long the solar minimum lasts.” In fact, something like this happened when Voyager 2 crossed the termination shock in 2007. Fluctuating solar activity made the boundary oscillate, so the spacecraft ended up crossing the termination shock several times.

Voyager 2 is also entering interstellar space in a completely different region from its sister ship. Whereas the latter traveled out of the heliosphere’s northern hemisphere (the planet-filled ecliptic plane is the equator), Voyager 2 is heading out of the southern hemisphere. Here, the galactic magnetic field is thought to be weaker, which may also affect the shape of the heliosheath. Having outbound spacecraft from both heliospheric hemispheres opens up fascinating opportunities for science. Both spacecraft have a working magnetometer, to measure the local magnetic field, and two particle detectors—one for solar particles and another for incoming cosmic rays. Only Voyager 2, however, continues to have a functioning plasma instrument, which could tell us much more about this unexplored region, including the temperature, density and velocity of any electrically charged material flowing around the spacecraft.

The Voyager team will continue to take measurements as both spacecraft travel away from the sun into a region called the outer heliosheath, although neither probe has much time remaining to make observations. “We’re probably only going to have four to five years left of data,” Christian says. But they may later be joined in this region by other spacecraft in the coming years. Although NASA’s Pioneer 10 and 11 spacecraft launched before the Voyagers paved the way on similar journeys beyond the Asteroid Belt to the outer solar system, eventually leading into interstellar space, they are no longer communicating with Earth. But NASA’s New Horizons spacecraft, which flew by Pluto and is about to conduct the most distant-ever rendezvous in the solar system, could continue operating into interstellar space, giving us a third functioning interstellar probe in coming decades.

Source: Voyager 2 Spacecraft Enters Interstellar Space

[Orionid]

Voyager 2 enters interstellar space
by Jeff Foust — December 10, 2018 [SpaceNews]


Both of NASA's twin Voyager spacecraft have crossed the heliopause and entered interstellar space, with scientists hoping the spacecraft will keep operating for up to a decade. Credit: NASA

WASHINGTON — As NASA’s Voyager 2 spacecraft enters interstellar space, project officials have high hopes that it and its twin spacecraft will continue to operate for as long as a decade.

NASA announced Dec. 10 that Voyager 2 passed what is known as the heliopause, the boundary between where the solar wind from the sun dominates and where the interstellar medium is dominant. That crossing, around Nov. 5, was detected by Voyager 2 in the form of a sharp drop in solar wind particles and corresponding increase in galactic cosmic rays detected by the spacecraft’s instruments.

The discovery, announced at the Fall Meeting of the American Geophysical Union here, comes six years after Voyager 1 also crossed the heliopause into interstellar space.

“This is a very exciting time again in Voyager’s 41-year journey,” said Ed Stone, Voyager project scientist at Caltech and former director of the Jet Propulsion Laboratory, during a press conference announcing the discovery.

The signature of the heliopause crossing from Voyager 2 is not quite the same as Voyager 1, Stone noted. “That’s what makes it interesting,” he said. “We’re in a different place — one is in the northern hemisphere and the other is in the southern hemisphere — and it’s a different time in the solar cycle. We would have been amazed if it looked the same.”

With both Voyager 1 and Voyager 2 beyond the heliopause, scientists are eager to combine those measurements with those from spacecraft and instruments within the sun’s heliosphere. “I’ve been studying galactic cosmic rays for many years from within our heliosphere,” said Georgia Denolfo, a space scientist at NASA’s Goddard Space Flight Center, at the press conference. “So it’s especially exciting to be able to think that we will be having a mission in the very same space that I have been studying, and many others, from afar.”

“I often get asked, ‘Is this it for Voyager?’” said Nicky Fox, director of the heliophysics division at NASA Headquarters. “Absolutely not. This is really for me the beginning of a new era of heliophysics science.”

Project officials are hopeful that this new era can last for several years, despite the age of the two Voyager spacecraft. Both were launched within weeks of each other in 1977 on missions to fly by Jupiter and Saturn. Voyager 2 also made flybys of Uranus and Neptune.

“Both spacecraft are very healthy, if you consider them senior citizens,” said Suzanne Dodd, Voyager project manager at JPL. “They are operating just fine.”

The spacecraft, powered by radioisotope thermoelectric generators (RTGs), are gradually losing power as their plutonium power sources decay. Dodd said the power produced by each spacecraft’s RTG is declining by about four watts per year, and the heat they generate that keeps the spacecraft warm is also declining.

Dodd said they’re closely watching the temperatures on Voyager 2, which are approaching the freezing point for its hydrazine fuel. “So we have to make a lot of trades, particularly with Voyager 2, between power and thermal,” she said.

As the power levels continue to decline, project officials will have to turn off some of the instruments on each spacecraft. “The difficult decisions are going to be made by Dr. Stone and the science team on which instruments to turn off first,” she said. “Those decisions will be made with getting the most science value back.”

Dodd said it’s possible for each spacecraft to continue operating for up to 10 more years. “My own personal goal would be to get these spacecraft to last 50 years” from their 1977 launch, she said. “If we get out to 2027, that will be a 50-year mission. I think that would be fantastic.”

Source: Voyager 2 enters interstellar space

[Orionid]

Voyager 2 Has Just Entered Interstellar Space, NASA Confirms
By Tom Hale 10 DEC 2018 [www.iflscience.com]



Going, going, gone. After a momentous 41-year journey, Voyager 2 has fulfilled its fate to leave the heliosphere and become the second interstellar spacecraft after Voyager 1, NASA has just confirmed.

The Voyager 2 probe was launched by NASA on August 20, 1977, 16 days before its twin Voyager 1, on a mission to explore Jupiter and Saturn. After this success, Voyager 2’s mission to explore the Solar System continued and it went on to become the first spacecraft to explore the ice giants, Uranus and Neptune. Ever since completing this part of its mission in 1989, the pair of galactic wanderers has been pointed towards deep space.

"For the second time in history, a human-made object has reached the space between the stars," NASA said in a statement on Monday. "NASA’s Voyager 2 probe now has exited the heliosphere – the protective bubble of particles and magnetic fields created by the Sun."


This image shows the crescents of Neptune and Triton, acquired by Voyager 2 just three days after its closest approach to Neptune in 1989. Voyager 2/ARC/NASA

It’s worth noting that the spacecraft has not totally “left the Solar System”. Here, we are noting that Voyager 2 has entered interstellar space by passing the heliosheath, the outermost layer of the Sun’s “magnetic bubble” beyond which the velocity of solar winds dramatically drop.

In Voyager 1's case, it proved difficult to definitively confirm it had passed the heliosheath and entered interstellar space, taking almost a year to verify. However, it’s been noted that the Voyager 2 spacecraft was picking up on an ever-decreasing quantity of heliospheric particles since November this year, fueling rumors that its grand exit was imminent. Throughout early December, a further decline was noted.


Graph showing the decreasing heliospheric particles being registered by the Voyager 2 spacecraft on December 9, 2018. NASA/JPL

It may be goodbye for now, but there is still work to be done. Unlike its twin, the Voyager 2 spacecraft is still armed with its Plasma Science (PLS) instrument, meaning it should be able to beam back some invaluable information on the nature of the heliosheath and the interstellar medium outside our Solar System.

“Working on Voyager makes me feel like an explorer, because everything we’re seeing is new,” added John Richardson, principal investigator for the PLS instrument and a principal research scientist at the Massachusetts Institute of Technology in Cambridge. “Even though Voyager 1 crossed the heliopause in 2012, it did so at a different place and a different time, and without the PLS data. So we’re still seeing things that no one has seen before.”

The Voyager spacecraft are also known for their Golden Records, two phonograph records that contain sounds and images of life on Earth, designed to act as a time capsule for intelligent extraterrestrial life or future humans.

Farewell, Voyager 2, it's been a pleasure.

Source: Voyager 2 Has Just Entered Interstellar Space, NASA Confirms

[Orionid]

Voyager 2 spacecraft enters interstellar space
It’s the second probe ever to exit the heliosphere
BY LISA GROSSMAN 12:57PM, DECEMBER 10, 2018 [Sciencenews]


OVER AND OUT  The Voyager 2 spacecraft has crossed into interstellar space, six years after its twin probe, Voyager 1. The two spacecraft are providing an unprecedented look at the edge of the sun’s influence (lighter blue bubble in this illustration).

Voyager 2 has entered interstellar space. The spacecraft slipped out of the huge bubble of particles that encircles the solar system on November 5, becoming the second ever human-made craft to cross the heliosphere, or the boundary between the sun and the stars.

Coming in second place is no mean achievement. Voyager 1 became the first spacecraft to exit the solar system in 2012. But that craft’s plasma instrument stopped working in 1980, leaving scientists without a direct view of the solar wind, hot charged particles constantly streaming from the sun (SN Online: 9/12/13). Voyager 2’s plasma sensors are still working, providing unprecedented views of the space between stars.

“We’ve been waiting with bated breath for the last couple of months for us to be able to see this,” NASA solar physicist Nicola Fox said at a Dec. 10 news conference at the American Geophysical Union meeting in Washington, D.C.

NASA launched the twin Voyager spacecraft in 1977 on a grand tour of the solar system’s planets (SN: 8/19/17, p. 26). After that initial tour was over, both spacecraft continued travelling through the bubble of plasma that originates at the sun.

“When Voyager was launched, we didn’t know how large the bubble was, how long it would take to get [to its edge] and whether the spacecraft could last long enough to get there,” said Voyager project scientist Edward Stone of Caltech.

For most of Voyager 2’s journey, the spacecraft’s Plasma Science Experiment measured the speed, density, temperature, pressure and other properties of the solar wind. But on November 5, the experiment saw a sharp drop in the speed and the number of solar wind particles that hit the detector each second. At the same time, another detector started picking up more high-energy particles called cosmic rays that originate elsewhere in the galaxy.

Waning wind

Voyager 2 saw a steep drop in solar wind, or heliospheric, particles on November 5, and recorded an increase in galactic cosmic ray particles, which come from the rest of the galaxy. Those signs make scientists think the spacecraft has left the sun’s protective bubble.

Using particles to track Voyager 2’s journey



Those measurements suggest that Voyager 2 has reached the region where the solar wind slams into the colder, denser population of particles that fill the space between stars. Voyager 2 is now a little more than 18 billion kilometers from the sun.

Intriguingly, Voyager 2’s measurements of cosmic rays and magnetic fields — which Voyager 1 could still make when it crossed the boundary — did not exactly match up with Voyager 1’s observations.

“That’s what makes it interesting,” Stone said. The variations are probably from the fact that the two spacecraft exited the heliosphere in different places, and that the sun is at a different part of its 11-year activity cycle than it was in 2012. “We would have been amazed if they had looked the same.”

The Voyagers probably have between five and 10 years left to continue exploring interstellar space, said Voyager project manager Suzanne Dodd from NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

“Both spacecraft are very healthy if you consider them senior citizens,” Dodd said. The biggest concern is how much power they have left and how cold they are — Voyager 2 is currently about 3.6° Celsius, close to the freezing point of its hydrazine fuel. In the near future, the team will have to turn off some of the spacecraft’s instruments to keep the craft operating and sending data back to Earth.

“We do have difficult decisions ahead,” Dodd said. She added that her personal goal is to see the spacecraft last until 2027, for a total of 50 years in space. “That would be fantastic.”

Source: Voyager 2 spacecraft enters interstellar space

[Orionid]

To Keep Boldly Going: NASA's New Plan for the Voyager Mission
By Paul Scott Anderson, on July 9th, 2019 [AS]


Artist’s concept of one of NASA’s Voyager spacecraft, including the location of the cosmic ray subsystem (CRS) instrument. Image Credit: NASA/JPL-Caltech

With all of the current and recent planetary missions throughout the Solar System, it may be easy to forget sometimes that there are still some older spacecraft that have been traveling for decades now. Two of these – Voyagers 1 and 2 – have even left the Solar System entirely, and now engineers need to figure out how to keep them active and functioning with much lower power levels and degrading thrusters.

“It’s incredible that Voyagers’ instruments have proved so hardy,” said Voyager Project Manager Suzanne Dodd, at NASA’s Jet Propulsion Laboratory in Pasadena, California. “We’re proud they’ve withstood the test of time. The long lifetimes of the spacecraft mean we’re dealing with scenarios we never thought we’d encounter. We will continue to explore every option we have in order to keep the Voyagers doing the best science possible.”

So how do you maintain these aging probes so they can continue to return science data, after nearly 42 years? Mission engineers have come up with a new plan.

This involves making some difficult choices.

There is only so much power available, especially after such a long time in deep space, and it becomes harder to maintain both the science instruments and the heaters. So engineers have had to choose what continues to receive power and what gets turned off now.


Diagram of the various instruments and other components of the two Voyager spacecraft (both are identical). Image Credit: NASA/JPL-Caltech

One option is to turn off heaters for instruments that can get by now without them.

On Voyager 2, the decision was made to turn off the heater for the cosmic ray subsystem (CRS) instrument, despite it still returning data even though temperatures had dropped to minus 74 degrees Fahrenheit (minus 59 degrees Celsius). That is lower than the temperatures at which the instrument was tested more than 42 years ago, down to minus 49 degrees Fahrenheit, or minus 45 degrees Celsius, a testament to just how well the CRS was built. This decision was based on the fact that the CRS can only take data in certain fixed directions, so a bit more limited in its use.

The CRS was valuable last November, proving that Voyager 2 had finally exited the Solar System’s heliosphere, the protective bubble created by a constant “wind” of ionized particles from the Sun. Voyager 2 is now considered to be in interstellar space.

Even with the CRS heater now turned off, Voyager 2 still has five functioning instruments: the CRS, two instruments to study plasma (a gas with ionized atoms) and a magnetometer (to measure magnetic fields).

Voyager 1 reached interstellar space back in August 2012, and is still collecting data with its own CRS. Other instruments are still functioning as well, including a plasma instrument, the magnetometer and the low-energy charged particle instrument.


Illustration showing the locations of both spacecraft as of December 2018, when Voyager 2 reached interstellar space. Voyager 1 crossed into interstellar space in 2012. Image Credit: NASA/JPL-Caltech.


Voyager 2 Enters Interstellar Space. Video Credit: NASA/JPL

Both Voyager 1 and Voyager 2 are powered by three radioisotope thermoelectric generators (RTGs), which produce heat via the natural decay of plutonium-238 radioisotopes. The heat is then converted into electrical power. But they don’t last forever, and the heat energy produced gradually declines, with 4 less watts of electrical power per year. As of now, 40% less power is being generated than at launch 42 years ago. Because of this, additional heaters may need to be turned off over the next few years. That is not an easy decision to make, since temperatures on both spacecraft need to be carefully controlled to prevent freezing of working (and needed) instruments. If the fuel lines froze, that could affect the thrusters, and the spacecraft might not be able to keep its antenna oriented toward Earth.

Heat isn’t the only problem however.

The thrusters on both spacecraft have started to degrade. In 2017, engineers noticed that some thrusters on Voyager 1 needed to give off more “puffs” or tiny pulses in order to maintain orientation of the spacecraft and keep the antenna pointed at Earth. To fix this, engineers switched to another set of thrusters that hadn’t been used in 37 years. It’s a good thing those additional thrusters were there and still functioning.

With both spacecraft now nearly 42 years into their missions, since their launch in 1977, it is not surprising that more problems are showing themselves now as instruments and other hardware age. But the mission engineers have come up with clever ways to keep them going, hopefully for at least several more years. They are now literally in unchartered territory, sending back new data about the boundary between our Solar System and interstellar space.


Illustration of the paths through the outer Solar System, including the Kuiper Belt, of Voyager 1 and Voyager 2, as well as Pioneer 10, Pioneer 11 and New Horizons. Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory

There is also NASA’s Interstellar Boundary Explorer (IBEX), a mission that explores that boundary too, but by remote sensing. NASA is also preparing the Interstellar Mapping and Acceleration Probe (IMAP), scheduled to launch in 2024, to further build on the Voyagers’ observations.

“Both Voyager probes are exploring regions never before visited, so every day is a day of discovery,” said Voyager Project Scientist Ed Stone, at Caltech. “Voyager is going to keep surprising us with new insights about deep space.”

Before leaving the Solar System, the Voyagers conducted a Grand Tour of the outer Solar System, sending back close-up images and data of Jupiter, Saturn, Uranus and Neptune, helping to revolutionize our understanding of these distant worlds.

Even after both probes eventually die, they will continue to silently navigate the space between our Solar System and the nearby stars, but they are not programmed to fly past any particular stars. Instead they will just drift alone through deep space, having accomplished their incredible missions of exploring the Solar System and beyond.

You can read more about the Voyager mission at the JPL website.

Source: https://www.americaspace.com/2019/07/09/to-keep-boldly-going-nasas-new-plan-for-the-voyager-mission/#more-108666

[Orionid]

The Voyagers' Odyssey
BY STAMATIOS M. KRIMIGIS, ROBERT B. DECKER [NS]
THIS ARTICLE FROM ISSUE JULY-AUGUST 2015 VOLUME 103, NUMBER 4 PAGE 284 DOI: 10.1511/2015.115.284

A mission intended to last a mere four years has extended into a decades-long journey to interstellar space.


Both Voyager 1 and Voyager 2 flew by Saturn, in 1980 and 1981, respectively, returning unprecedented images of that planet before continuing farther into space. Voyager 1 became the first craft in interstellar space in 2012; Voyager 2 will soon follow. Image courtesy of NASA/JPL-Caltech.

When the two Voyager spacecraft were launched in 1977, they followed a legacy of space exploration that was only two decades old, but which had accomplished much in that time. The first spacecraft to orbit Earth, Sputnik 1, was launched in 1957, and NASA’s Mariner 2 spacecraft passed Venus on December 14, 1962. Mariner 4, which swung by Mars on July 15, 1965—some 50 years ago—was the first to carry a camera. Pioneer 10 and 11’s flybys of Jupiter in the early 1970s, and Pioneer 11’s continuation to Saturn in 1979, gave a first glimpse of the complexity of these two planetary systems. The outer planets (Jupiter, Saturn, Uranus, and Neptune) as a group, however, remained basically unexplored until the two Voyager spacecraft arrived.
https://www.americanscientist.org/article/the-voyagers-odyssey

Voyager 1 Nears Jupiter Rendezvous
By John Noble Wilford Feb. 27, 1979

BEYOND the orbit of Mars and the asteroid belt, out where sunlight is diminished and the worlds are large and virtually unexplored, Voyager 1 is moving swiftly toward a rendezvous next Mon- day with Jupiter and several of the moons in its mighty embrace.

PASADENA, Calif.

After a journey of 18 months, the 1,800‐pound American spacecraft is more than 400 million miles from Earth and within five million miles of Jupiter. All is reported to be in readiness for the . most comprehensive close‐up ‘investigation ever undertaken of Jupiter, the solar system's largest planet, and its major Satellites, two of which are bigger than the planet Mercury.

Voyager is approaching the planet at a rate ofinore than 600,000 miles a day, gathering speed from the pull of Jovian gravity. This Is a powerful attraction, for Jupiter is big enough to contain 1,200 Earths and, although it is primarily a gaseous body, It has a mass 317.9 times that of Earth.

Spacecraft on Target

Voyager is on target, after a brief rocket maneuver last week “trimmed” its‐trajectory. The spacecraft crossed the orbit of Sinope, the most distant of Jupiter's 13 known moons, on Feb. 10 and will spend more than six weeks swinging through the Jovian system. Its course was selected carefully so that it could fly within safe distances of Jupiter and five Jovian moons — Amalthea, lo, Europa, Ganymede and Callisto — then be able to proceed on a 20month cruise to Saturn.

Despite some nagging malfunctions early in flight, Voyager is “working very normally,” according to Robert J. Parks, the project manager at the Jet Propulsion Laboratory here. The spacecraft is a large drum‐shaped structure dominated by a 12‐foot‐wide dish antenna and bristling with other antennas and booms carrying the scientific instruments and two slowscan television cameras. For nearly two months, Voyager has been studying the puzzling radio emissions from Jupiter and returning Increasingly spectacular photographs of the planet's multicolored bands of upper‐atmosphere clouds and the familiar Great Red Spot. Earlier this month, the photography began surpassing in resolution and clarity the pictures taken by Pioneers 10 and 11, which flew by Jupiter in 1973 and 1974. Voyager 1 will be observing Jupiter longer and in greater detail than the Pioneers did.

As the moment of closest encounter approaches, project scientists exude the excitement of anticipated discovery. Dr. Bradford A. Smith of the University of Arizona, the leader of the imaging science team, remarked that he had worked on many photographic missions to the planets but “to me, this is unquestionably the most exciting one of all.”

“We're extending our eyes into the outer solar system and into the unknown,” Dr. Smith said. “Not since Mariner 4 to Mars, some 15 years ago, have we been less prepared, less certain of what we expect to see. The next couple of weeks will be great.”

Early results, reported last week, suggest what is in store. Voyager cameras and other instruments have detected what appears to be a persistent jet stream of frozen ammonia moving at a speed of 350 miles an hour above the Jovian clouds. Hydrogen and helium are known to be the principal constituents of the planet.

Sequences of time‐lapse pictures disclose the curious phenomenon of dark orange “hot spots” traveling through the upper cloud layers. Sometimes, one spot overtakes another and seems to gobble it up; at other times two spots merge for as long as 12 days, then break apart.

Although the Great Red Spot has been observed through ground‐based telescopes for more than three centuries, Voyager photographs show that it undergoes striking changes. Dr. Smith said the color of the huge, hurriCane‐like feature seems to have faded, becoming more dark brown, since the Pioneer. pictures in 1974. There also appear to be “atmospheric currents swirling around it that weren't there before.”

“We have found,” Dr. Smith concluded, “that Jupiter is far more complex in atmospheric motions than we had ever imagined.”

Voyager is also beginning to return some distant photographs of the larger Jovian moons. Dark reddish polar re gions are visible on lo. Europa appears to be coated with ice. Bright equatorial areas are visible on Callisto's dark face.

During the encounter phase of the mission, Voyager will fly within 258,000 miles of Amalthea, the innermost moon, early on March 5. Then it will fly within 174,000 miles of Jupiter's southern hemisphere at 7:05 A.M. New York time on the same day. Its closest approach to a Jovian body will be at lo, 12,752 miles away. The spacecraft will swing within 71,500 miles of Ganymede, the largest moon, and 455,000 miles of Europa — both on March 5. Early the next day, it will fly within 78,359 miles of Callisto and then begin searching for any heretofore undiscovered Jovian moons. There has been a sighting from

Earth, as yet unconfirmed, of a 14th moon.

All of Voyager's scientific instruments have been turned on and are working. In addition to wide‐angle and narrow‐angle television cameras, Voyager carries a cosmic‐ray detector, an infrared interferometer‐spectrometer‐radiometer, a low‐energy chargedparticle detector, magnetometers, a photopolarimeter, a planetary radioastronomy instrument, plasma and plasma‐wave experiments and an ultraviolet spectrometer.

These instruments were selected and designed for three broad areas of study of Jupiter: atmospheric sciences, satellite observations and investigations of magnetic fields and the trapped radiation environment.

With the ultraviolet and infrared sensors, for example, project scientists expect to learn much about the composi tion, temperature and structure of Jupiter's turbulent atmosphere. This should give them answers to such questions as: Why are the bands of light zones and dark belts so well‐defined? What gives them their colors? What lies beneath the upper clouds?

The dynamics of the atmosphere will be studied through photography. Dr. Edward C. Stone, a physics professor at the California Institute of Technology and the project's chief scientist, said that the time‐lapse photography shows mass motions of the Jovian clouds and enables scientists to measure velocities of small features and flow patterns and perhaps to identify the physical processes that cause the multi‐colored belts, zones and spots.

“Up to now, we have been working with pictures that are like one frame out of a movie,” Dr. Stone explained. “Now we have a movie, if you will, and can see flow patterns.”

From the pictures already taken at a distance, Dr. Stone said, scientists are identifying regions of high interest “so we can zoom in on them during the close approach.” Close‐up shots of the Great Red Spot should produce pictures of sufficient detail that objects five miles across can be distinguished.

Voyager should return data on the temperatures, composition, surface texture and general nature of Jupiter's four major satellites. The two largest ones, Ganymede and Callisto, are thought to be almost entirely ice, although there is a hypothesis that they possess oceans of liquid water covered by a thick crust of ice. Voyager has already detected ice covering Europa, but no one knows the depth of the ice or much of anything else about the satellite.

“These are objects unlike anything we have photographed in a solar system before,” Dr. Stone remarked.

Voyager will be concentrating much of its attention on lo, the most puzzling of the satellites. The closest large one to Jupiter, lo is blanketed with salts of various kinds and may be pocked with fresh,lunar‐like craters. It is ringed by a cloud of sodium vapor, perhaps generated by intense radiation bombardment of the satellite's surface. Voyager's photopolarimeter will analyze the composition of the sodium cloud, as well as study the density of satellite atmospheres, if there are any, and determine the texture and composition of the satellites’ surfaces.

Flux Tube to Be Penetrated

As lo moves through Jupiter's strong magnetic field, it generates an electric current that flows along the magnetic field lines connecting the satellite and the planet. This cylindrical region .is called the “flux tube.” Voyager is aimed so that it can penetrate the flux tube for five minutes during the spacecraft's swing under Io's south pole.

Several days before the close encounter, Voyager will enter the general sphere of Jupiter's magnetic field. As Pioneer 10 discovered, Jupiter has a powerful magnetic field and is surrounded by radiation belts similar to the Van Allen belts around Earth, but thousands of times more intense. This vast, rapidly spinning region makes Jupiter a major source of several types of radiation.

One of the mission's objectives will be to get a better understanding of the size and shape and nature of Jupiter's magnetic field. From the results of the two Pioneer missions, scientists believe the size and shape of the magnetic field changes periodically.

Voyager 1 is the first of two identical spacecraft in the $400‐million project of exploration. Only four months behind is Voyager 2, bound for an encounter with Jupiter on July 9. It will also go to Saturn and may even continue on to Uranus, with the encounter there occurring in January 1986.

This is possible because of a rare alignment at this time of all the outer planets, enabling a carefully aimed spacecraft to use the gravitational force of one planet to give it a boost of energy and a change of course toward the next planet. This shortens the flight time to the far outer planets and brings them within the range of present spacecraft capabilities.

There is also a possibility, albeit remote, that Voyager 2 could be targeted at Uranus to proceed on to Neptune, arriving there in September 1989. If that should happen, it would mean that history could say of the first 32 years of the space age, from 1957 to 1989, that vehicles of human design completed the initial reconnaissance of all the planets of the solar system, save Pluto, and of many of the planets’ fascinating moons.

NASA
https://www.nytimes.com/1979/02/27/archives/voyager-1-nears-jupiter-rendezvous-voyager-1-nears-jupiter.html

Voyager l Finds Stunning Variety on Jupiter's Moons
By John Noble Wilford June 5, 1979

AFTER three months of examining the photographs and data from Voyager l's rendezvous with Jupiter, scientists have concluded that they have never seen anything in the solar system to compare to the four major Jovian moons —Io. Europa. Ganvmede and Callisto — each a distinct world and a source of continuing surprise.

Reflecting the excitement of such a discovery, the Voyager photographic interpretation team, led by Dr. Bradford A. Smith of the University of Arizona, reported in the June 1 issue of the journal Science:

“The bodies in the Jupiter system explored by Voyager 1 do not resemble closely either the planets in the inner solar system or one another. The wide range of unexpected findings is due both to the real differences between the outer and the inner solar system and to the depth of our prior ignorance. The sense of novelty would probably not have been greater had we explored a different solar system.”

Before Voyager 1 cruised through the environs of Jupiter last March, the four largest of the 13 known Jovian moons had been little more than vague points of light in the sky. Galileo discovered them in 1610, which is why they are called the Galilean satellites. Other astronomers plotted their orbits and determined that Ganymede and Callisto were each as big as the planet Mercury and that Io and Europa were about the size of Earth's moon. But the nature and appearance of the moons were beyond the resolving power of pre‐Voyager science.

The report in Science and discussions by planetary specialists at the spring meeting of the American Geophysical Union in Washington last week painted this picture of the moons of Jupiter:

IO‐When scientists thought about it at all, they speculated that Io, the innermost of the Galilean satellites, would be a cold, essentially dead world resembling Earth's moon. Instead, Voyager found Io to be a diverse, colorful world (bright orange‐red mottled by irregular patches of white), devoid of lunar‐like impact craters and alive with spewing volcanoes. Finding the first active volcanoes elsewhere in the solar system was Voyager's most surprising and spectacular discovery.

Further analysis in recent weeks has led geologists to identify eight erupting volcanoes on Io. Some of the eruptions, greenish in color, sent plumes of gases and other material more than 150 miles above the surface at velocities of as much as 1,200 miles an hour. For unknown reasons, the volcanoes are distributed around the equatorial region.

According to Dr. John C. Pearl of the Goddard Space Flight Center, reporting on Voyager's infrared measurements, Io's volcanoes seem to be cooler than had been expected. Most of Io's surface has temperatures of about 235 degrees below zero Fahrenheit. One of the volcanic plumes showed a temperature of about 80 degrees above zero. If the volcanoes were venting molten sulfur, as has been speculated, the ternperatures should have been about 230 degrees above zero.

The cause of Io's violent volcanoes has not been determined. But the report by Dr. Smith and his team said a “likely explanation” was tidal heating generated in Io's interior by the competing gravitational forces of Jupiter, in one direction, and Europa and Ganymede, in others.

In addition to the erupting volcanoes, Io photographs show signs of more than 100 huge depressions that resemble the craters, or calderas, of volcanoes on Earth and Mars. But in contrast to most terrestrial and Martian calderas, few of the ones on Io appear to be associated with high domes or other mountain structures. In fact, the only rugged mountains seen on Io thus far occur mainly in the polar regions.

Mother phenomenon found primarily in the polar regions is “blue snow,” the discovery of which was announced last week at the American Geophysical Union meeting. A recent re‐examination of Io photography disclosed 30 to 40 wisps of blue material, probably venting gases that condensed into snow,

EUROPA - Although Voyager 1 did not make a close approach to Europa, the cameras were able to see enough to show that it was a much different place than Io. The most distinctive features standing out in the moon's pale reflected light were long linear structures criss‐crossing the visible surface. Some are estimated to be more than 100 miles wide and 1,000 miles long. Geologists said the lines resemble faults and “are strongly suggestive” of globalscale processes that are moving and shaking Europa's crust.

Recent Earth‐based, near‐infrared observations indicate large amounts of water, probably in the form of ice, on the surface of Europa.

GANYMEDE - The largest of Jupiter's moons, Ganymede is also believed to be covered with water‐ice mixed with rock and, because of its low density compared to such rocky bodies as Earth, may be 50 percent water by weight.

Ganymede's surface, heavily marked with apparently ancient impact craters, bears some resemblance to Earth's moon. The photographs also show puzzling patterns of bright and dark grooves traversing the surface, suggesting some crustal movements on Ganymede, too.

But “a striking fact” about Ganymede, according to the report in Science, is the absence of major relief.

CALLISTO - The most impressive feature on Callisto is an enormous multi‐ring meteorite Impact basin with a central, circular patch of light-colored material about 180 miles wide. Radiating out from it are at least 8 to 10 bright discontinuous ridges more or less equally spaced, extending out about 850 miles.

“The flatness and unusual ring spacing,” the report in Science said, “are presumably due to the difference in material properties between an icerich crust and the silicate crusts of the moon and Mercury. Viscous flow during or subsequent to the impact event probably reduced the topographic relief.”

In early July, scientists expect to reap a new harvest of information about Jupiter and its moons. Voyager 2, an identical spacecraft, will fly by the moons on July 9 in such a way as to obtain high‐resolution photographs of the hemispheres not surveyed by Voyager 1.

B.J. Poricbon
https://www.nytimes.com/1979/06/05/archives/voyager-1-finds-stunning-variety-on-jupiters-moons.html

NASA’s Voyager Will Do More Science With New Power Strategy
April 26, 2023

(...) With those options now exhausted on Voyager 2, one of the spacecraft’s five science instruments was next on their list. (Voyager 1 is operating one less science instrument than its twin because an instrument failed early in the mission. As a result, the decision about whether to turn off an instrument on Voyager 1 won’t come until sometime next year.)

In search of a way to avoid shutting down a Voyager 2 science instrument, the team took a closer look at a safety mechanism designed to protect the instruments in case the spacecraft’s voltage – the flow of electricity – changes significantly. Because a fluctuation in voltage could damage the instruments, Voyager is equipped with a voltage regulator that triggers a backup circuit in such an event. The circuit can access a small amount of power from the RTG that’s set aside for this purpose. Instead of reserving that power, the mission will now be using it to keep the science instruments operating. (...)
https://www.jpl.nasa.gov/news/nasas-voyager-will-do-more-science-with-new-power-strategy

[Orionid]

Sonda znajduje się obecnie ok. 24 mld km od Słońca (163,287 AU).

Contact restored with NASA’s Voyager 1 space probe
DOYLE RICE   USA TODAY, April 22, 2024

Contact restored.

That was the message relieved NASA officials shared after the agency regained full contact with the Voyager 1 space probe, the most distant human-made object in the universe, scientists announced Monday.

For the first time since November, the spacecraft is now returning usable data about the health and status of its onboard engineering systems, NASA said in a news release. (...)
https://voyager.jpl.nasa.gov/news/

Voyager 1 is sending data back to Earth for the first time in 5 months
Ashley Strickland By Ashley Strickland, CNN  Published 7:13 PM EDT, Mon April 22, 2024


An artist's illustration depicts Voyager 1 as it travels through interstellar space, or the space between stars. NASA/JPL-Caltech

(...) By investigating the readout, the team determined the cause of the issue: 3% of the flight data system’s memory is corrupted. A single chip responsible for storing part of the system’s memory, including some of the computer’s software code, isn’t working properly. While the cause of the chip’s failure is unknown, it could be worn out or may have been hit by an energetic particle from space, the team said. (...)
https://edition.cnn.com/2024/04/22/world/voyager-1-communication-issue-cause-fix-scn/index.html

A Reverie for the Voyager Probes, Humanity’s Calling Cards
By Dennis Overbye Aug. 21, 2017


Credit...Elwood Smith

In the shadow, one might say, of the Great American Eclipse, a major anniversary in the history of space exploration — and indeed cosmic consciousness — is being celebrated.

It was 40 years ago, on Aug. 20 and Sept. 5, 1977, that a pair of robots named Voyager were dispatched to explore the outer solar system and the vast darkness beyond.

What resulted was nothing less than a reimagining of what a world might be and what strange cribs of geology and chemistry might give rise to life in some form or other.

It was a real-life Star Trek adventure, but the crew stayed home, communicating with their two spacecraft through a billion-mile bucket brigade of data bits.

New computer programs went one way, and data — including scratchy photos of new landscapes and the whispering moans of interplanetary plasma fields — came back the other way. All of it was being carried out by a robot brain with the memory capacity of an old-fashioned digital watch.

The spacecraft had been designed to make what scientists called the Grand Tour, taking advantage of a once-every-175-year planetary alignment. Voyager 1 and Voyager 2 were to use the gravity of the outer planets to slingshot from Jupiter to Saturn, and to Uranus and Neptune, and then beyond the edge of the sun’s domain into interstellar space.

In the end, only half the tour — to Jupiter and Saturn — was actually approved. But the Voyager crew packed for a much longer journey. When they lifted off 40 years ago, the two spacecraft carried golden records inscribed with pictures and sounds from Earth, greetings from President Jimmy Carter and instructions on how to play it all.

The Voyagers would observe the universe, and give something back to whoever might one day find them.

The robot emissaries cruised the solar system through presidential administrations, wars and scandals, and the Challenger disaster, which happened as Voyager 2 was pulling away from Uranus.

At every planetfall, the crew members, a little older and a little grayer each time, reconvened at the Jet Propulsion Laboratory in Pasadena, Calif., for a weeklong marathon of discovery, a circus of science on the fly.

With imagery returned by probes, what had been fuzzy dots in the world’s biggest telescopes bloomed into worlds.

Back on Earth, some theoreticians claimed to be homing in on a putative theory of everything, an Einsteinian dream of an equation simple enough to be inscribed on a T-shirt.

But in space, scientists were finding that such theories were no help against nature’s endless capacity to invent and surprise. Each new world revealed by the Voyagers was a head-scratcher.

Once upon a time, it was presumed that the moons of the outer planets, so far from the sun and so close to the origins of the solar system, would be boring ice balls, geologically and in every other way dead.

But then Voyager 2 spotted volcanoes spraying fountains of sulfur from the surface of Jupiter’s innermost moon, Io. On close inspection, Saturn’s rings — the jewels of the solar system — dissolved into 10,000 grooves, like a vinyl record’s, braided, kinked and patrolled by tiny moonlets.

Voyager 1 plumbed a fat, smoggy atmosphere of Titan, where nitrogen and methane rains fall on a frozen slush pile of hydrocarbons and oily lakes, and then headed off toward interstellar space.

Voyager 2 cruised on to Uranus, mysteriously tipped on its axis and surrounded by rings that make it look like a bull’s eye.

The probe passed the restful methane blue of Neptune, besmirched by a dark spot, and its moon Triton, an ice rock flowing like soft ice cream with geysering nitrogen.

I’ve never had more fun as a science writer than during those weeklong encounters in Pasadena, when my colleagues and I — a little older and grayer ourselves, humbler but no wiser about the tricks that nature might be up to out there in the realm of dark and ice — gathered to watch the scientists watch their new worlds.

The television screens in the press room showed the latest images as they came in from the Voyager spacecraft. We had the same view as the scientists.

If on some distant world there had been a sign saying “Drink Coke,” or a pyramid, what we liked to call “the press room imaging team” would have had a chance to see it first.

Casting aside years of learned reserve and an addiction to speaking and writing in the passive voice, Voyager scientists had to parade to daily news briefings and venture explanations that they knew they would have to take back a few days later about things they (and we) had seen for the first time only a few hours before.

Part of the joy of “The Farthest: Voyager in Space,” a documentary to air on PBS on Wednesday, is reliving those moments of bafflement and intellectual ambition.

It was at the Voyager encounters that I first got to know my colleagues in the newspaper business, and learned by going out to dinner with them that they could drink me under the table before the appetizers arrived.

Other nights were spent in the bluesy, smoky company of science writers and planetary astronomers listening to the space ballads of Jonathan Eberhart, the late correspondent for Science News and a well-known folk singer. A rock band named for a feature of Titan, The Titan Equatorial Band, played at parties and gatherings.

The music stopped the morning after Voyager 2 passed by Uranus, on Jan. 28, 1986, when the Space Shuttle Challenger blew up with seven astronauts aboard, including Christa McAuliffe, the teacher in space.

That morning the televisions in a hushed newsroom at J.P.L. had Uranus on one screen and the Y-shaped cloud of the explosion on the other. By noon, my newspaper friends had packed their bags and headed for Houston or Cape Canaveral.

Voyager 2 went on. By the time it reached Neptune — the gatekeeper of our planetary realm, now that Pluto doesn’t count — the engineers at J.P.L. had enlisted antennas around the Earth to listen in unison, catching the trickle of data bits flowing from almost three billion miles away.

Chuck Berry, whose music was included on the spacecraft records, came to the lab to play for a Voyager farewell party.

There would be one last act. In 1990, as it ascended the void, Voyager 1’s crew commanded it to turn its cameras backward and snap a family portrait of the worlds it was leaving forever behind.

The Earth appears on this picture as the famous “pale blue dot” in a wash of scattered sunlight, a “mote of dust suspended in a sunbeam,” as the astronomer and cosmic sage Carl Sagan later described it.

Voyagers’ cameras are now turned off, but the probes continue to report back on the conditions in deepest space.

In October 2012, magnetic field and cosmic ray measurements indicated that Voyager 1 had reached the edge of the magnetic bubble that the sun extends like an umbrella over the planets, blocking outside radiation.

Voyager 1 was in interstellar space, the first human artifact to escape the solar system. It and its twin will go on circling the galaxy, long after it has ceased speaking to us.

In the fullness of galactic time, the Voyagers may be found, but by then the human race may be long extinct. The Voyager record might be the only physical remnant, the last lonely evidence that we, too, once lived in this city of stars, among these islands of ice and rock.

Back then, we were looking forward to an exploration of space that would go on forever. It was magic, and we were all on the spaceship.

A correction was made on Aug. 24, 2017: An article on Tuesday about the accomplishments of the Voyager 1 and Voyager 2 space missions misstated the date on which the PBS documentary “The Farthest” was broadcast. It was shown Wednesday night; it had not already aired at the time the article was published.
https://www.nytimes.com/2017/08/21/science/voyager-nasa-40th-anniversary.html
https://twitter.com/airandspace/status/1782861762011771028

Dr. Buzz Aldrin @TheRealBuzz Last edited 5:50 PM · Dec 2, 2024
It looks like there is some good news with Voyager 1 – communications have been restored, allowing the spacecraft to keep sending data back. The fact that Voyager 1 is 47 years old and still functioning and providing information to us is a testament to the quality of the research and engineering that went into its development by @NASA a half-Century ago. Voyager 1 is 15.4 billion miles from Earth – still venturing into deep space, on its own, carrying out its mission. An astounding accomplishment!
https://space.com/space-exploration/missions/voyager-1-interstellar-spacecraft-finds-its-voice-again-as-nasa-restores-communications

https://twitter.com/TheRealBuzz/status/1863626896916832598