Tag: Juno

Juno team creates dramatic animation of Ganymede/Jupiter fly-by

10:49 am

Using images from Juno’s fly-by of both Ganymede and Jupiter on June 7th and 8th, the science team has produced a dramatic animation, with background music, showing that fly-by from the point of view of the spacecraft.

I have embedded it below the fold.

The 3:30-minute-long animation begins with Juno approaching Ganymede, passing within 645 miles (1,038 kilometers) of the surface at a relative velocity of 41,600 mph (67,000 kph). The imagery shows several of the moon’s dark and light regions (darker regions are believed to result from ice sublimating into the surrounding vacuum, leaving behind darkened residue) as well as the crater Tros, which is among the largest and brightest crater scars on Ganymede.

It takes just 14 hours, 50 minutes for Juno to travel the 735,000 miles (1.18 million kilometers) between Ganymede and Jupiter, and the viewer is transported to within just 2,100 miles (3,400 kilometers) above Jupiter’s spectacular cloud tops. By that point, Jupiter’s powerful gravity has accelerated the spacecraft to almost 130,000 mph (210,000 kph) relative to the planet.

Among the Jovian atmospheric features that can be seen are the circumpolar cyclones at the north pole and five of the gas giant’s “string of pearls” – eight massive storms rotating counterclockwise in the southern hemisphere that appear as white ovals. Using information that Juno has learned from studying Jupiter’s atmosphere, the animation team simulated lightning one might see as we pass over Jupiter’s giant thunderstorms.

The lightning shown on Jupiter, while entertaining, is a complete fantasy. The flashes are much too bright and large. At the scale created, some would cover the Earth. In reality, that lightning wouldn’t be visible until you are very very close, and even then probably difficult to spot in the vastness of Jupiter.

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Craters on Ganymede’s striped surface

11:27 am

Craters on Ganymede
Click for full image.

Cool image time! The photo to the right, cropped to post here, is a color enhanced section taken from of one of the images taken by Juno when it did a close fly-by of the Jupiter moon Ganymede back on June 7, 2021.

The enhancement was done by citizen scientist Navaneeth Krishnan, using a wider Juno image of Ganymeded enhanced by citizen scientist Kevin Gill. That wider image is below, and marks the area covered by this first image with a white box.

In this one picture we can see many of the geological mysteries that have puzzled scientists since the Galileo orbiter first took close-up images back in the 1990s. We can see patches of grooved terrain with the grooves in the different patches often oriented differently. We can also see bright and dark patches that while they overlay the grooved terrain they bear no correspondence to those grooved patches. And on top of it all are these small craters, impacts that obviously occurred after the formation of the grooves.
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Juno takes first close-up images of Ganymede since 2000

9:21 am

Ganymede as seen by Juno
Click for full image.

Ganymede as seen by Juno
Click for full image.

On June 7th the Jupiter orbiter Juno made its first close fly-by of Ganymede, taking the first close-up images of this Jupiter moon since the orbiter Galileo flew past in 2000.

The first two images from NASA Juno’s June 7, 2021, flyby of Jupiter’s giant moon Ganymede have been received on Earth. The photos – one from the Jupiter orbiter’s JunoCam imager and the other from its Stellar Reference Unit star camera – show the surface in remarkable detail, including craters, clearly distinct dark and bright terrain, and long structural features possibly linked to tectonic faults.

…Using its green filter, the spacecraft’s JunoCam visible-light imager captured almost an entire side of the water-ice-encrusted moon. Later, when versions of the same image come down incorporating the camera’s red and blue filters, imaging experts will be able to provide a color portrait of Ganymede. Image resolution is about 0.6 miles (1 kilometer) per pixel.

In addition, Juno’s Stellar Reference Unit, a navigation camera that keeps the spacecraft on course, provided a black-and-white picture of Ganymede’s dark side (the side opposite the Sun) bathed in dim light scattered off Jupiter. Image resolution is between 0.37 to 0.56 miles (600 to 900 meters) per pixel.

Both images are to the right, each slightly reduced to post here. These images of this moon of Jupiter, the largest moon in the solar system and about 26% larger than the planet Mercury, reveal many of the same unsolved geological mysteries uncovered when the Galileo orbiter photographed it two decades ago. As I wrote in my Chronological Encyclopedia

Closer inspection of Ganymede revealed a strange topography, including patches of grooved terrain (not unlike the surface of a vinyl record) overlaying other patches of grooved terrain, the different patches oriented in random and totally unrelated directions. Moreover, the surface is overlain by bright and dark patches (the bright patches thought to be caused by water frost) that often had no apparent correspondence to topographical features. Planetary geologists could only scratch their heads in wonderment.

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Jupiter’s changing and unchanging Great Red Spot

9:40 am

The changing Great Red Spot of Jupiter
Click for full figure.

In a paper published in March in the Journal of Geophysical Research: Planets, scientists (using images from amateurs, the Hubble Space Telescope, and Juno, scientists) have mapped out the interactions between Jupiter’s Great Red Spot, the longest known storm on the gas giant, and the smaller storms that interact with it as they zip past.

The series of images to the right come from figure 5 of their paper, showing the Spot over a period of three days. The Spot in these images is about 9,000 miles across, less than half the size it had been back in the late 1800s.

The black arrows mark the shifting location and shape of one smaller vortice as it flowed past the Spot from east to west along its northern perimeter, ripping off portions of the Spot as it passed. From the paper’s absract:

During its history, the [Great Red Spot] has shrunk to half its size since 1879, and encountered many smaller anticyclones and other dynamical features that interacted in a complex way. In 2018–2020, while having a historically small size, its structure and even its survival appeared to be threatened when a series of anticyclones moving in from the east tore off large fragments of the red area and distorted its shape. In this work, we report observations of the dynamics of these interactions and show that as a result the [Spot] increased its internal rotation velocity, maintaining its vorticity but decreasing its visible area, and suffering a transient change in its otherwise steady 90‐day oscillation in longitude.

…From the analysis of the reflectivity of the [Spot] and flakes and model simulations of the dynamics of the interactions we find that these events are likely to have been superficial, not affecting the full depth of the [Spot]. The interactions are not necessarily destructive but can transfer energy to the [Spot], maintaining it in a steady state and guaranteeing its long lifetime.

In other words, the changes seen only involved the Spot’s cloud tops, even if those tops were many miles thick. The storm itself is much deeper, with its base embedded strongly inside Jupiter and largely unaffected by these passing smaller storms.

Why the Spot exists and remains so long-lived remains an unsolved mystery.

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Looking into one of Jupiter’s smaller cyclones

9:47 am

A northern cyclone on Jupiter
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Cool image time! The photo to the right, cropped and reduced to post here, was taken by the Juno probe orbiting Jupiter and enhanced first by citizen scientist Kenneth Gill and then further enhanced by citizen scientist Navaneeth Krishnan.

Sadly all the link tells us about this storm is that it is in the northern hemisphere. Based upon the colors, my guess is that it located at the high latitude where Jupiter’s bands transition to the chaotic region of storms at the poles, as seen in this earlier wide image of the gas giant’s south pole.

No scale is provided, but an earlier image of other northern hemisphere storms suggests this storm would probably cover the state of Arizona.

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Jupiter’s southern jet streams

9:21 am

Jupiter's southern jet streams
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Cool image time! The photo to the right, rotated and reduced slightly to post here, shows the southern jet streams in Jupiter’s atmosphere. From the press release:

The storm known as the Great Red Spot is also visible on the horizon, nearly rotated out of view as Juno sped away from Jupiter at about 30 miles per second (48 kilometers per second), which is more than 100,000 mph (160,900 kilometers per hour).

Citizen scientist Tanya Oleksuik created this color-enhanced image using data from the JunoCam camera. The original image was taken on Dec. 30, 2020 as the Juno spacecraft performed its 31st close flyby of Jupiter. At the time, the spacecraft was about 31,000 miles (about 50,000 kilometers) from the planet’s cloud tops, at a latitude of about 50 degrees South.

According to data obtained by Juno, these bands of storms extend about 1,800 miles into Jupiter’s interior, much deeper than expected.

The Great Red Spot is at about 22 degrees south latitude, so this tells us that this picture covers Jupiter’s southern hemisphere from about the equator down to about 80 degrees.

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NASA extends mission of Juno and InSight probes

8:08 am

NASA has decided to extend the missions of Juno and InSight probes, giving both several more years to gather data.

InSight main goal for the two-year extension will be to gather more seismic data of Mars. They will also continue their efforts to get the heat sensor into the ground, but that will have a lower priority.

Juno will be able to slowly adjust its orbit to better study Jupiter’s north polar regions, thus developing a more complete first rough map of the gas giant’s internal structure and atmosphere. The changing orbit will also allow the first close fly-bys of some of Jupiter’s moons, the first in more than twenty years.

The moon flybys could begin in mid-2021 with an encounter with Ganymede, Jupiter’s largest moon, at a distance of roughly 600 miles (1,000 kilometers), Bolton said last year.

After a series of distant passes, Juno will swoop just 200 miles (320 kilometers) above Europa in late 2022 for a high-speed flyby. Only NASA’s Galileo spacecraft, which ended its mission in 2003, has come closer to Europa.

There are two encounters with Jupiter’s volcanic moon Io planned in 2024 at distances of about 900 miles (1,500 kilometers), according to the flight plan presented by Bolton last year. Juno will be able to look for changes on the surfaces of Jupiter’s moons since they were last seen up close by NASA’s Voyager and Galileo probes.

While it will take images, Juno’s camera is not particularly high resolution. The main effort will be to use its instruments to study the surface make-up of the moons.

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Jupiter’s stormy southern polar regions

2:46 pm

Jupiter's polar regions
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Cool image time! The photo to the right shows the southern polar regions of Jupiter. The image, taken by Juno during its 29th close-fly of Jupiter, was enhanced by a citizen scientist who only goes by the nickname Flury-21. This in fact was this person’s first try at enhancing a Juno image. He or she did a nice job, but provided no additional information other than saying that he “used lightroom to enhance the image and mostly used the dehaze effect.”

Works nicely nonetheless to illustrate how the bands that dominate Jupiter’s equatorial and mid-latitude regions disappear at the pole. Instead, the pole is a region of chaotic independent hurricanes, many bigger than North America. Other images from Juno suggest that they change relatively quickly. For example, compare this image of the south pole with an earlier one taken during the 28th fly-by. While we might not be looking at the same hemisphere, it is hard to believe there is no overlap between both images. Yet I can find no corresponding features.

The two images of course were taken months apart, and thus it is not surprising the storms have changed completely. However, I also suspect, given their size, that even over this time span some storms have survived, but changed so much it is hard to link them together. The only way to do this would be to have an orbiter close enough all the time to make movies. Unfortunately, Juno cannot do this, and I don’t expect any orbiter like this to reach Jupiter for many decades.

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Analyzing the evolving “small” storms in Jupiter’s atmosphere

12:09 pm

The vortices in Jupiter's polar regions
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The cool image to the right is another Juno photo of Jupiter enhanced by citizen scientist Gerald Eichstädt. This time Eichstädt also did some analysis of the motions and interactions of many vortices found in the northern polar regions of Jupiter. The image to the right has been cropped and reduced to post here, with the state of Arizona, about 400 by 300 miles in size, added for scale. There is more annotation in the full image.

As Eichstädt writes:

Large vortices in an atmosphere layer of a rotating planet can be roughly split into two classes, cyclonic and anticyclonic vortices.

Based on this rough classification, two interacting vortices can either be of the same or of opposite sign. Tightly interacting vortices of opposite sign tend to mutually propel each other, hence the whole pair, if they are of similar strength and size.

Tightly interacting vortex pairs of the same sign tend to merge. More distant like-signed vortex pairs may essentially repel each other. Interacting vortices tend to create filaments, some of which may split into fragments and further collapse into streets of small eddies.

He also notes that in future orbits Juno will provide closer views of this stormy region, as with the orbit the closest point shifts northward.

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The beauty of Jupiter’s Great Red Spot

10:37 am

The cool image below needs little explanation. It shows, in all its beauty, Jupiter’s Great Red Spot, taken from a Juno image during the spacecraft’s 21st fly-by of Jupiter. Citizen scientists Navaneeth Krishnan S enhanced the image only slightly, but that slight work brought out the details quite wonderfully.

Jupiter and its Great Red Spot
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The face on Jupiter

9:56 am

The face on Jupiter!

Citizen scientist Gerald Eichstädt has created a two-image blink animation from Juno images of Jupiter that shows the changes in the two oppositely rotating storm vortices, shown on the right. As he notes.

Two vortices or eddies, one cyclonic, the other one anticyclonic, can propell themselves mutually and slowly within the overall context they are embedded in.

…The rotation of the two vortices is perceptible in the image sequence taken within nine minutes. The cyclonic eddy is located at the left, the anticyclonic one at the right. The motion of the vortex pair, however, is too slow to be resolved. But the morphology of the cloud tops points towards a relative upward motion in this rendition.

That the two storms also invoke face I am sure also had something to do with his decision to showcase this data. Unlike the face on Mars, this face is real, though relatively temporary. It will eventually break apart as Jupiter’s storms evolve.

The animation can be seen at the link.

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Juno science team proposes fly-bys of Jupiter’s moons

8:30 am

The Juno science team has proposed doing fly-bys of three of Jupiter’s moons, should NASA extend the mission beyond ’21.

Juno’s five-year primary mission phase ends in July 2021, and mission managers have proposed an extension that would continue operations until September 2025. The spacecraft’s additional orbits around Jupiter will bring Juno closer to the planet’s moons, allowing for a more diversified set of scientific targets.

…The moon flybys would begin in mid-2021 with an encounter with Ganymede, Jupiter’s largest moon, at a distance of roughly 600 miles (1,000 kilometers), according to Bolton.

After a series of distant passes, Juno would swoop just 200 miles (320 kilometers) above Europa in late 2022 for a high-speed flyby. Only NASA’s Galileo spacecraft, which ended its mission in 2003, has come closer to Europa.

There are two encounters with Jupiter’s volcanic moon Io planned in 2024 at distances of about 900 miles (1,500 kilometers), according to the flight plan presented by Bolton last month.

The extended mission would also allow scientists to get a better look at Jupiter’s north pole.

NASA will decide on the extension by the end of the year. From a cost and scientific perspective, it makes perfect sense to extend this mission for as long as possible. Compared to launching a new mission, extending an active one is far cheaper. It is also already in place.

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Flying over Jupiter

11:02 am

Cool movie time! Using images produced by Juno in orbit around Jupiter, citizen scientist Kevin Gill has produced a very nice movie of the spacecraft’s 27th fly-by on June 2, 2020.

During the closest approach of this pass, the Juno spacecraft came within approximately 2,100 miles (3,400 kilometers) of Jupiter’s cloud tops. At that point, Jupiter’s powerful gravity accelerated the spacecraft to tremendous speed — about 130,000 mph (209,000 kilometers per hour) relative to the planet.

I have embedded the movie below the fold. The choice of a piece of music by Vangellis might seem hokey, but I think in this case it works very nicely. I also was impressed with the addition of some 3D depth near the movie’s beginning.
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Juno’s 28th fly-by of Jupiter

10:20 am

Cool movie time! Below is a short movie created by citizen scientist Gerald Eichstädt from images taken by Juno as it swung past Jupiter on its 28th close pass since arriving in orbit in 2016.

In natural colors, Jupiter looks pretty pale. Therefore, the still images are approximately illumination-adusted, i.e. almost flattened, and consecutively gamma-stretched to the 4th power of radiometric values, in order to enhance contrast and color.

Like for all its previous flybys, Juno approached Jupiter roughly from north, and left Jupiter looking towards the soutern hemisphere. Closest approach to Jupiter was 3,500 km above the nominal IAU 1-bar level, and near 25.3 degrees north (planetocentric), according to long-term planning of November 2017.

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Lightning and mushballs on Jupiter

3:49 pm

Artist's illustration of Jupiter lightning
Click for full illustration.

Using data from Juno, scientists now theorize that Jupiter produces what they dub “shallow lightning” as well as ammonia-water hailstones dubbed “mushballs.”

The image to the right, cropped and reduced to post here, is only an artist’s illustration of the lightning. Sadly Juno’s camera doesn’t have the resolution to capture such flashes.

An unexpected form of electrical discharge, shallow lightning originates from clouds containing an ammonia-water solution, whereas lightning on Earth originates from water clouds.

Other new findings suggest the violent thunderstorms for which the gas giant is known may form slushy ammonia-rich hailstones Juno’s science team calls “mushballs”; they theorize that mushballs essentially kidnap ammonia and water in the upper atmosphere and carry them into the depths of Jupiter’s atmosphere.

As with the InSight results below, there is much uncertainty with these results, especially the hypothesis of mushballs. These features fit their present data from Juno, but we must remember that the data is still somewhat superficial.

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Jupiter’s south pole

10:59 am

The storms at the south pole of Jupiter
Click for full image.

Cool image time! The photo to the right, rotated and reduced to post here, was taken by Juno during its 28th close orbital fly-by of Jupiter, and then processed by citizen scientist Hemant Dara.

While not the first Juno image of the poles of Jupiter, this photo illustrates very well the evolution of the gas giant’s deep atmosphere as you move from the equator to the pole. From the equator to the high mid-latitudes the planet’s rotation, producing a day only 10 hours long, organizes that atmosphere into jet streams that form the bands that astronomers have spied from Earth since the first telescopes.

At the pole the influence of that rotation seems to wane, or at least influence the atmosphere differently, so that the storms seem to form randomly and incoherently.

The image also shows that there appear to be several types of storms at the south pole. Some appear as tight spirals, similar to hurricanes. Others appear chaotic, with no consistent shape, almost like clouds on Earth.

The processes that would explain all this are not yet understood, in the slightest, and won’t be until we get orbiters at Jupiter able to watch the atmosphere continuously, as we do here on Earth. Then it will be possible to assemble movies of the formation and dissipation of these storms, and begin (only begin) to decipher what causes them.

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New storm outbreak on Jupiter

10:00 am

Clyde's Spot
Click for full image.

A new storm, dubbed Clyde’s spot after its discoverer, developed suddenly in late May on Jupiter, and has been imaged by Juno during its most recent close fly-by of the gas giant planet.

The image to the right, cropped to post here, focuses in on this spot. It is the feature in the center of the full image, with the Great Red Spot to the upper left.

The new feature was discovered by amateur astronomer Clyde Foster of Centurion, South Africa. Early on the morning of May 31, 2020, while imaging Jupiter with his telescope, Foster noticed a new spot, which appeared bright as seen through a filter sensitive to wavelengths of light where methane gas in Jupiter’s atmosphere has strong absorption. The spot was not visible in images captured just hours earlier by astronomers in Australia.

On June 2, 2020, just two days after Clyde Foster’s observations, Juno performed its 27th close flyby of Jupiter. The spacecraft can only image a relatively thin slice of Jupiter’s cloud tops during each pass. Although Juno would not be travelling directly over the outbreak, the track was close enough that the mission team determined the spacecraft would obtain a detailed view of the new feature, which has been informally dubbed “Clyde’s Spot.”

The feature is a plume of cloud material erupting above the upper cloud layers of the Jovian atmosphere. These powerful convective “outbreaks” occasionally erupt in this latitude band, known as the South Temperate Belt

The coolest thing about this is that the storm was spotted by an amateur, using a ground-based telescope, within hours of its inception.

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Jupiter in glorious color

9:21 am

Jupiter in glorious color
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Cool image time! The photograph on the right, reduced to post here, was color enhanced by citizen scientist Emma Walimaki from the original Juno image in order to bring out the features and storms visible in the upper storm layers of Jupiter.

The photo was taken during Juno’s 25th close fly-by of the gas giant, and thus we are only seeing a small portion of Jupiter’s sphere.

In comparing this image with the original, it appears that Walimaki simply made the colors that were already there brighter and more distinctive. Thus, these colors represent real data. Jupiter’s cloud tops are really blue, orange, tan, and brown, unlike Earth’s consistently and boringly white water clouds.

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Juno’s first measurement of water content on Jupiter

3:40 pm

The uncertainty of science: Scientists today released their first measurements from Juno of the amount of water found in Jupiter’s atmosphere.

The Juno science team used data collected during Juno’s first eight science flybys of Jupiter to generate the findings. They initially concentrated on the equatorial region because the atmosphere there appears more well-mixed, even at depth, than in other regions. From its orbital perch, the radiometer was able to collect data from a far greater depth into Jupiter’s atmosphere than the Galileo probe – 93 miles (150 kilometers), where the pressure reaches about 480 psi (33 bar).

“We found the water in the equator to be greater than what the Galileo probe measured,” said Cheng Li, a Juno scientist at the University of California, Berkeley. “Because the equatorial region is very unique at Jupiter, we need to compare these results with how much water is in other regions.”

These results remain very preliminary, especially because they have not yet gathered data at higher latitudes. Regardless the amount so far detected, 0.25% of all molecules in Jupiter’s atmosphere. seems remarkably small, suggesting that Jupiter has relatively little hydrogen or oxygen in its atmosphere.

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A new Juno flyover movie above Jupiter

10:01 am

Citizen scientist Brian Swift has created a new movie from images taken by Juno during its December 25th close pass of Jupiter, the 24th such flyby of the spacecraft’s mission.

I have embedded the movie below. While it isn’t as spectacular as previous movies (see here, here, here, and especially here and here), as it appears that either Juno did not get quite as close, or Swift did not shape it to give that impression, it is still most breathtaking.

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