Juno detects the largest volcanic event on Io yet

Changes on Io since April 2024
Changes on Io since April 2024. Click for original image.

Infrared detection of volcanic hot spot
Infrared detection of volcanic hot spot.
Click for original image.

Using Juno’s Italian JIRAM infrared instrument image as well as its optical camera, scientists have detected what appears to be the largest volcanic event yet measured on the Jupiter moon Io, covering an area larger than Lake Superior,

Scientists with NASA’s Juno mission have discovered a volcanic hot spot in the southern hemisphere of Jupiter’s moon Io. The hot spot is not only larger than Earth’s Lake Superior, but it also belches out eruptions six times the total energy of all the world’s power plants.

…The JIRAM science team estimates the as-yet-unnamed feature spans 40,000 square miles (100,000 square kilometers). The previous record holder was Io’s Loki Patera, a lava lake of about 7,700 square miles (20,000 square kilometers). The total power value of the new hot spot’s radiance measured well above 80 trillion watts.

The pictures above were taken by Juno’s optical camera during the last three close flyby’s, looking down at the south pole, with the red arrows indicating the change to the pole’s right during each pass. The infrared image to the right shows a similar view during the fly-by, and shows that same hot spot as the bright area to the pole’s right.

Juno will do another fly-by of Io in March, though from a greater distance. Scientists plan to use both instruments to see how this hot spot has changed again since the end of December.

Juno spots changes on Io’s surface in just a two-month span

Before and after images by Juno of volcanic ring on Io
Click for original image.

New photos taken just two months apart by Juno of a region dubbed Nusk Patera on the Jupiter moon Io showed the appearance of a distinct ring that had hardly been there before.

The pictures, taken during two recent fly-bys of the moon, are above, and show the change. From the caption:

A red ring formed around Nusku Patera in the two months between the spacecraft’s 58th flyby on Feb. 3, 2024, and its 60th on April 9, 2024. The ring obscures some nearby features like Creidne Patera. This ring, 683 miles (1,100 kilometers) wide is likely from a Pele-type plume rich in sulfur. Similar transient red rings were observed by NASA’s Galileo mission around Grian Patera and Surt and were associated with intense but short-lived thermal “outburst” eruptions.

In other words, sulfur from eruption from the central vent/caldera was flung into the sky enough that when it eventually settled back down it landed in a ring about 340 miles away from the center.

Other data from Juno, also released this week here and here, detected fresh lava flows at another volcanic region of Io dubbed, Zal Patera.

Io’s volcanoes get their lava from separate magma chambers, not a global underground ocean of magma

Io's interior as presently theorized
Click for original animation.

Using data collected from Juno’s multiple fly-bys of the Jupiter moon Io, scientists now hypothesize that the moon does not have a global underground ocean of magma, feeding its many volcanoes, but that instead each volcano is fed its lava from a separate magma chamber.

The graphic to the right illustrates the present conclusion. You can read the paper here [pdf]. From the press release:

The Juno team compared Doppler data from their two flybys with observations from the agency’s previous missions to the Jovian system and from ground telescopes. They found tidal deformation consistent with Io not having a shallow global magma ocean.

“Juno’s discovery that tidal forces do not always create global magma oceans does more than prompt us to rethink what we know about Io’s interior,” said lead author Ryan Park, a Juno co-investigator and supervisor of the Solar System Dynamics Group at JPL. “It has implications for our understanding of other moons, such as Enceladus and Europa, and even exoplanets and super-Earths. Our new findings provide an opportunity to rethink what we know about planetary formation and evolution.” [emphasis mine]

The highlighted words indicate the significance of this data. It possibly suggests that the underground oceans of water that have been theorized for these other moons — where life could possibly exist — might be mistaken. Instead, they might have smaller pockets of water, similar to Io’s many magma chambers.

Everything here however is uncertain, including these new conclusions about Io. We just don’t have enough data from any of these moons to make any definitive conclusions.

A map of Io’s hot spots based on Juno data

The hot spots on Io
Click for original image.

The uncertainty of science: Using the JIRAM infrared camera on the Jupiter orbiter Juno, scientists have now created a global map of volcanic activity, showing where it appears the hottest and greatest activity is located.

That data is illustrated by the graphic to the right, taken from figure 1 of the paper. The top row shows the coverage of the planet, with Io’s southern hemisphere getting the fewest observations. The bottom row shows the observed regions with the greatest heat. This quote from the abstract is most revealing:

Using JIRAM, we have mapped where volcanoes are producing the most power and compared that to where we expect higher heat flow from the interior models. Our map doesn’t agree with any of these models very well. JIRAM observed more volcanic activity at the poles than we expected to see based on previous observations. However, since the south pole was only observed twice, it’s possible that these observations don’t represent the average volcanic activity of the south pole. Very bright volcanoes that may have been continuously active for decades were also imaged during these Juno fly-bys, some of which are nearer the poles than the equator.

The conflict between the data and the theories could very well be explained simply by the short term nature of these observations. The models could very well be right, over centuries. For example, the new volcano discovered by Juno is near the equator, suggesting with time those models will turn out to be correct.

Or not. A lot more observations will have to be made of Io before any model of its volcanic activity can be considered trustworthy.

Juno discovers new volcano on Io

New volcano on Io
Click for original image.

By comparing images taken twenty-seven years apart by the the Jupiter orbiters Galileo and Juno, scientists have discovered that during that time a new volcano appeared on the volcano-strewn Jupiter moon Io.

The two pictures to the right show the surface change on Io during those 27 years.

Analysis of the first close-up images of Io in over 25 years, captured by the JunoCam instrument on NASA’s Juno mission, reveal the emergence of a fresh volcano with multiple lava flows and volcanic deposits covering an area about 180 kilometres by 180 kilometres. The findings have been presented at the Europlanet Science Congress (EPSC) in Berlin this week.

The new volcano is located just south of Io’s equator. Although Io is covered with active volcanoes, images taken during NASA’s Galileo mission in 1997 did not see a volcano is in this particular region – just a featureless surface.

If anything, it has been somewhat surprising how little change the new Juno images have found on Io’s surface, considering its intensely active volcanic geology, with volcano plumes from eruptions captured in images repeatedly. Some volcanoes have shown change, but new features such as this new volcano have not previously been identified.

At the same time, the amount of high resolution imagery of the planet’s surface has been somewhat limited. Galileo sent back far fewer pictures than planned because its main antenna never deployed, and Juno had only a handful of close fly-bys. It will take a mission dedicated to studying Io to better map its violent surface.

Juno infrared data confirms existence of at least eleven lava lakes on Io

Cartoon describing Io's lava lakes
Click for original image.

Using infrared data from the Jupiter orbiter Juno, obtained during a close fly-by in May 2023 of the moon Io, scientists have identified what appear to be at least eleven active lava lakes, all filled with liquid magma under a surface crust and having a stable perimeter that apparently does not overflow the rim.

You can read the research paper here. The graphic to the right is figure 6 from the paper, describing two models for explaining why the lava in these lakes never rises high enough to pour out.

Unlike the April fly-by, which got as close as 10,777 miles and produced some amazing imagery, the May fly-by only got within 22,000 miles, but its course allowed Juno’s infrared instruments to collect good global data for six hours.

The JIRAM data reveal a common set of thermal characteristics for at least ten patera, with bright “thermal rings” around the perimeter of their floors. Loki, Surt, Fuchi, Amaterasu, Mulungu, Chors, and Dazhbog paterae, two unnamed paterae (here referred to as UP1 and UP2), and two other potential additional paterae (not discussed further because the spatial resolution is poor), all show the same pattern of surface temperatures.

That data suggested that each patera was a hot lava lake, with a stable rim in which little magma ever overflowed. As the scientists conclude in their paper, “Present findings highlight Io’s abundant lava reserves, resembling lava lakes on Earth in some ways, yet distinctly different from any other phenomena observed in the Solar System.” The scientists also note that no missions are being planned right now to get a better look at Io.

Analysis of Io’s atmosphere suggests it has been volcanically active for its entire 4+ billion year history

By analysizing the isotobes in Io’s atmosphere, scientists now believe that it has been volcanically active since its initial formation at the birth of the solar system 4.5 billion years ago.

de Kleer et al. found that both elements [ sulfer- and chlorine-bearing molecules] are highly enriched in heavy isotopes compared to average Solar System values due to the loss of lighter isotopes from the upper atmosphere as material is continuously recycled between Io’s interior and atmosphere. The findings indicate that Io has lost 94% to 99% of the sulfur that undergoes this outgassing and recycling process. According to the authors, this would require Io to have had its current level of volcanic activity for its entire lifetime.

This data suggests that Io, as well as Jupter’s other three large Galilean moons (Europa, Calisto, and Ganymeded) have been in their present orbits since their formation 4.5 billion years ago. It also means that, while Io’s geological history keeps getting wiped out by its volcanic activity, the other three contain detailed geological records of the solar system’s entire history. Combine that with the geological data we will eventually get from Mars, it appears that we shall someday be able to document that history far beyond anything expected.

Io on Juno’s 60th close fly-by of Jupiter

Volcano Plumes on Io
Click for original image.

Io as seen by Juno
Click for original image.

The photos above and to the right were both taken by Juno during its 60th close fly-by of Jupiter on April 9, 2024. The image above, cropped slightly to post here, was processed by citizen scientist Gerald Eichstädt, who states the following:

The stretched and enlarged crop is derived from a reprojected Io image with a margin of 100 km greater than Io’s nominal radius. Two plumes are obvious. The plume on the night siide is visible in several frames of the PJ60 Io sequence.

That Juno captures plumes like this on every close fly-by tells us the extent of activity that is on-going on the moon. Basically, eruptions are continuous and never ending.

The image to the right, reduced and sharpened to post here, was processed by Eichstädt and enhanced by citizen scientist Thomas Thomopoulos. It gives us a global view of Io’s many volcanoes and flood lava plains.

During that 60th fly-by Juno’s closest approach to Io was 10,778 miles. Though close, this is not as close as the approach of 930 miles during the 57th and 58th fly-bys. Nor will future fly-bys be as close again. This is essentially Juno’s last close look at the volcano world.

The volcanic world of Io, as seen by Juno in all its fly-bys

Map of Io
Click for full resolution image.

The mosaic of images above, reduced and sharpened to post here, was compiled by citizen scientists Gerald Eichstädt, Jason Perry, and John Rogers from images taken of the Jupiter moon Io during the three close fly-bys by the orbiter Juno that occurred during its 55th, 57th, and 58th orbits. From the caption:

Global map of Io by JunoCam, combining maps from PJ55, PJ57 and PJ58. Both the sunlit side and the Jupiter-lit-dark side are included. PJ55 map by Gerald Eichstädt; PJ57 map by Jason Perry; PJ58 map by Gerald Eichstädt and John Rogers. Some scaling and shifting was performed in order to align the maps with each other and with the USGS Voyager/Galileo map. Colours were adjusted for better compatability. –John Rogers.

A labeled version, showing the names of many volcanoes but only of the areas photographed during the most recent 58th orbit fly-by on February 3, 2024, can be seen here.

As Juno’s later fly-bys will be progressively farther away, we will no longer get better views of Io until another spacecraft arrives in a Jupiter orbit capable to returning to Io, possibly decades from now. Though Europa Clipper will arrive in Jupiter orbit April 2030, that orbit is designed to repeatedly fly close past Europa, and will likely never get close to Io.

Thus, this map provides a baseline for determing any changes that occur on Io in the coming years.

Juno completes its closest approach of the Jupiter moon Io

Io on February 3, 2024
Click for full image.

The Jupiter orbiter Juno successfully completed its 58th close fly-by of the gas giant, during which it also made its closest approach to the volcanic moon Io, zipping past at a distance of 932 miles. The image of Io to the right, cropped and reduced to post here, was taken at that closest Io approach, and shows a mountain on the horizon as well as a large shield volcano in the center (the dark splotch), with a major lava flow to the south. The picture was processed by citizen scientist Brian Swift.

Another image, processed by Björn Jónsson, shows the differences at one volcano dubbed Loki between the December 30, 2023 and the February 3, 2024 flybys. It appears that the brightness of the apron of lava that surrounds the volcano changes significantly depending on the lighting and the angle of view. In December it was almost black. In February it was greyish silver, almost shiny.

Another image, processed by Andrea Luck, captured faint eruption plumes on Io’s edge, caused by an ongoing eruption just beyond the horizon.

Juno still has four more flybys of Io coming up, but none will be as close as the February 3rd approach.

The Surt volcano on Io

The Surt volcano on Io in close-up
Click for original image.

Cool image time! The picture to the right, rotated, reduced, and sharpened to post here, was taken by Juno during its 57th close-fly of Jupiter on December 30, 2023. It shows of one of the many volcanoes that cover and continually recoat the surface of the Jupiter moon Io.

The picture was initially processed by citizen scientist Gerald Eichstädt. Thomas Thomopoulos then zoomed in and added additional enhancements to this particular area. (I thank Thomas for his additional help in making this post happen.)

The location is an active volcano named Surt, which has been observed to erupt several times since the 1970s, with its February 2001 eruption the most powerful yet observed on Io, though the pictures by the Jupiter orbiter Galileo taken before and after revealed few significant surface changes.

The picture itself shows a region where major changes have definitely occurred. The large arc of mountains across the photo’s center suggests the remaining half of a large caldera, its northern half now either buried or destroyed. The deep obvious hole inside that crescent appears to be the main vent from which the recent eruptions have spewed, as indicated by the light-colored apron surrounding it.

In the southwest section of that large mountain arc is a distinct ridgeline with a small circular curve in its middle that suggests a former volcanic cone, its northern half now gone.

To put it mildly, Io appears a very alien place, shaped entirely and continuously by endlessly volcanic eruptions that spread lava across its entire surface repeatedly.

First Juno images of Io from December 30th fly-by

Io as seen by Juno on December 30, 2023
For original global image go here. For original of inset go here.

The first raw Juno images taken of the Jupiter moon Io during its close fly-by on December 30, 2023, the closest in more than twenty years, have been released by the science team and citizen scientists have begun processing them.

The global picture to the right, rotated and reduced to post here, was processed by Kevin Gill. The inset of the volcanic mountains near the terminator was processed by Thomas Thomopoulos. As he notes, to obtain better detail he enhanced the colors and image and then zoomed in.

In the inset, note the northeast flows coming off the two mountains near the center. With the lower mountain, this flow appears to lie on top of a larger flow that extended out almost to the mountain to the right.

Io is a planet of continuous volcanic activity. For example, when the global image above was taken, the plume of a volcano eruption was visible on the right horizon, as shown in this version, its exposure adjusted by Ted Stryk. Catching such eruptions on Io is not unusual, considering its continuous volcanic activity generated by the tidal forces the planet undergoes from its orbit around Jupiter. In fact, the very first plume was imaged in 1979 by Voyager 1 during its short fly-by, and proved a hypothesis of such activity that scientists had only published one week earlier.

More Io images by Juno, enhanced by citizen scientists

Io in natural and enhance colors
Click here for original of top image,
here for bottom.

Since Juno completed its 55th close swing past Jupiter on October 15, 2023, including the closest fly by of its volcano-covered moon Io since the 1990s, citizen scientists have been grabbing the spacecraft’s raw images of the moon and enhancing them to bring out the details.

Immediately after the fly-by I posted on October 17, 2023 the top image to the right, processed by Ted Stryk. This version attempted to capture the view of Juno is natural color. As I noted then, “The dark patches are lava flows, with the dimensions of mountains along the terminator line between night and day clearly distinguishable.”

The bottom picture to the right was first processed by citizen scientist Gerald Eichstädt, who like Stryk attempted to capture Io’s natural colors. Thomas Thomopoulos then took Eichstädt’s image and enhanced the colors as well as reduced the brightness, in order to bring out the details as much as possible.

I have rotated, cropped, and reduced this bottom image further to post it here.

In comparing this image with earlier pictures of Io, taken by both Juno and Galileo in the 1990s, there is evidence that some of the lava flows visible now have changed significantly in the intevening time. This is not a surprise, as volcanic eruptions take place on Io so frequently that it has not unusual to capture one in the rare times close up images are possible, going back to the discovery of volcanic activity by Voyager-1 in 1979.

It will take a bit of time for scientists, both professional and amateur, to pick out the specific changes. That work will be further aided by Juno’s next fly-by on December 30, 2023, where it will dip to less than 1,000 miles of the surface.

New Io images from Juno

Io as seen on October 15, 2023 by Juno
Click for original image.

The Jupiter orbiter Juno completed its 55th close pass of the gas giant on October 15, 2023, which also included a close pass of the Jupiter moon Io. The science team has now released the first images of Io from that fly-by, and several citizen scientists have released their processed versions.

The picture to the right, cropped, reduced, and sharpened to post here, was processed by Ted Stryk. It is the best view seen of this volcano-covered world since the Galileo orbiter in the 1990s. The dark patches are lava flows, with the dimensions of mountains along the terminator line between night and day clearly distinguishable.

An even closer look will occur during Juno’s 57th Jupiter orbit on December 30, 2023, when it will get within 1000 miles of Io’s surface, crossing the mid- to high latitudes of the planet’s western hemisphere.

Juno gets new close-up images of Jupiter’s moon Io

Io as seen by Juno in July 2023
Click for original image.

During its July close fly-by of Jupiter the orbiter Juno also flew past the moon Io, getting within 14,000 miles. The picture to the right, cropped and reduced to post here, was one of the images taken during that fly-by and subsequently processed and color enhanced by citizen scientist Thomas Thomopoulos.

The picture was taken at about the spacecraft’s closest point. It shows the splotched and volcanic surface of Io, which because it orbits close to Jupiter tidal forces cause it to have an intensely active volcanic surface. All the black features are either volcanoes or lava flows. This set of all of Juno’s Io images taken during the fly-by, enhanced by citizen scientist Gerald Eichstädt, also shows a volcanic plume in the shadowed portion of the planet, just beyond the terminator, which Eichstädt believes is a mountain dubbed Tohil Mons.

Even closer flybys are scheduled for December ’23 and February ’24, both getting within 1,000 miles of the surface.

Juno’s next fly-by of Io coming on July 30

Io as seen by Juno
An image of Io from the March fly-by

The Juno science team is gearing up for the spacecraft’s next fly-by of the Jupiter moon Io, scheduled for July 30, 2023.

When NASA’s Juno mission flies by Jupiter’s fiery moon Io on Sunday, July 30, the spacecraft will be making its closest approach yet, coming within 13,700 miles (22,000 kilometers) of it. Data collected by the Italian-built JIRAM (Jovian InfraRed Auroral Mapper) and other science instruments is expected to provide a wealth of information on the hundreds of erupting volcanoes pouring out molten lava and sulfurous gases all over the volcano-festooned moon.

The image to the right was taken from 33,000 miles during the March fly-by, almost three times farther away. The dark spots are volcanoes, and some showed significant change from earlier images.

Juno captures close-up images of Jupiter’s moon Io

Io as seen by Juno

On March 1, 2023 the Jupiter orbiter Juno passed within 33,000 miles of the gas giant’s moon Io, getting its first close-up images.

Several citizen scientists have processed those images. The photo to the right, cropped and reduced to post here, was created by Andrew R Brown. This particular picture was one of five taken by Juno during the fly-by. Jason Perry processed all five here, with this caption:

Most of the dark spots seen across Io’s surface are the result of volcanic eruptions. These include East Girru, a dark spot that was not seen the last time Io was seen at this resolution during the New Horizons encounter with Jupiter in February 2007. East Girru was undergoing a major eruption at the time but hadn’t had time to produce a new lava flow before the end of the week-long encounter. This small flow field, measuring 3,200 square kilometers (1,390 square miles) in size, may have also been reactivated during an eruption in October 2021, as seen by Juno JIRAM.

Another apparent surface change is at Chors Patera, which has undergone a significant reddening since Galileo last observed it in October 2001. Reddish materials on Io are indicative of the presence of short-chain sulfur and are often associated with high-temperature, silicate volcanism. Additional dark spots near the terminator, the boundary between Io’s day and night sides, are the shadows of tall mountains. The dark spot at middle right in the upper right image may be due a mountain 5500 meters (18,000 feet) tall.

The smallest object resolved in this image is about 22 miles across.

Jupiter and two of its Moons, as seen by Cassini during 2018 fly-by

Cool video time! Back in December 2000 the spacecraft Cassini made a fly-by of Jupiter on its way to Saturn, which it then orbited from 2004 to 2017. In 2018 JPL scientist Kevin Gil took the images from that flyby to create a short movie, first showing two of Jupiter’s moons, Io and Europa, as they drifted above the Great Red Spot.

Then, for the second half of the movie Gil used Cassini images taken when in orbit around Saturn to show the moon Titan moving across the rings of Saturn.

I have embedded this short video below. If I had posted this back in 2018, I don’t remember. No matter. It is amazing enough to watch again.

Hat tip BtB’s stringer Jay.
» Read more

A new hotspot map of Io, based on Juno data

Hot spot map of Io
Click for original figure.

Scientists have compiled a new map of the many volcanic hotspots on the Jupiter moon Io, based on data obtained by Juno, including 23 spots previously undetected. From the paper’s abstract:

We mapped the hot spot distribution on Io’s surface by analyzing the images acquired by the JIRAM instrument onboard the Juno spacecraft. We identified 242 hot spots, including 23 not present in other catalogs. A large number of the new hot spots identified are in the polar regions, specifically in the northern hemisphere. The comparison between our work and the most recent and updated catalog reveals that JIRAM detected 82% of the most powerful hot spots previously identified and half of the intermediate-power hot spots, thus showing that these are still active. JIRAM detected 16 out of the 34 faint hot spots previously reported.

The map above is taken from figure 2 of the paper. The data, when compared to other earlier data, confirms that many of these hot spots are long-lived, and have been erupting now for decades.

Largest volcanic eruption in years detected on Io

Using instruments on a ground-based telescope, one scientist based at the Planetary Science Institute (PSI) in Arizona has detected the largest volcanic eruption in years on the Jupiter moon Io.

PSI Senior Scientist [Jeff] Morgenthaler has been using IoIO, located near Benson, Arizona to monitor volcanic activity on Io, since 2017. The observations show some sort of outburst nearly every year, but the largest yet was seen in the fall of 2022. Io is the innermost of Jupiter’s four large moons and is the most volcanic body in the Solar System thanks to the tidal stresses it feels from Jupiter and two of its other large satellites, Europa and Ganymede.

IoIO uses a coronagraphic technique which dims the light coming from Jupiter to enable imaging of faint gases near the very bright planet. A brightening of two of these gases, sodium and ionized sulfur, began between July and September 2022 and lasted until December 2022. The ionized sulfur, which forms a donut-like structure that encircles Jupiter and is called the Io plasma torus, was curiously not nearly as bright in this outburst as previously seen. “This could be telling us something about the composition of the volcanic activity that produced the outburst or it could be telling us that the torus is more efficient at ridding itself of material when more material is thrown into it,” Morgenthaler said.

The material released by this eruption could impact Juno during future close approaches of Jupiter.

Juno snaps heat image of Jupiter’s volcano-covered moon Io

Io's volcanoes
Click for full image.

The image to the right, cropped and reduced to post here, was taken on July 5, 2022 by one of the infrared instruments on the Jupiter orbiter Juno of the moon Io, known for having many many active volcanoes.

This infrared image was derived from data collected by the Jovian Infrared Auroral Mapper (JIRAM) instrument aboard Juno. In this image, the brighter the color the higher the temperature recorded by JIRAM.

Each bright spot is an active volcano, some of which have been in the past photographed during eruptions. In fact, the first such photo was taken in March 1979 by the Voyager-1 spacecraft just after its fly-by of Jupiter, and was the first time any active volcano outside of Earth had ever been identified.

What made that discovery more profound was that only a week earlier scientists had published a paper predicting active volcanoes on Io, caused by the strong tidal forces from Jupiter’s gravity.

Since then planetary scientists have been studying Io’s volcanism repeatedly, tracking the evolution of specific volcanoes over time as they erupt and then become dormant.

Dunes on Jupiter’s volcano moon Io?

Dunes on Io?
Click for full image.

The uncertainty of science: According to a just published paper, scientists now propose that the dune-like ridges long known to exist on Io, Jupiter’s volcano-covered moon, might actually be dunes, even though Io has no real atmosphere.

The photo to the right, cropped, reduced, and annotated to post here, was taken by the Galileo while it orbited Jupiter from 1995 to 2003. It illustrates what the scientists believe is the proposed process:

McDonald and his colleagues used mathematical equations to simulate the force required to move grains on Io and calculated the path those grains would take. The study simulated the movement of a single grain of basalt or frost, revealing that the interaction between flowing lava and sulfur dioxide beneath the moon’s surface creates venting that is dense and fast moving enough to form large dune-like features on the moon’s surface, according to the statement.

In what might be a monumental understatement about the reality of interplanetary geology, McDonald said this in the press release: “This work tells us that the environments in which dunes are found are considerably more varied than the classical, endless desert landscapes on parts of Earth.”

Damn right. The possibility of unexpected geology of all kinds on the millions of planets, moon, and asteroids not yet studied is endless, and guaranteed.

NASA extends mission of Juno and InSight probes

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.

Io’s shadow on Jupiter

Io's shadow on Jupiter
Click for full image.

Citizen scientists Kevin Gill and Tanya Oleksuik have used raw images from Juno to create several really cool images of the eclipse shadow of Io moving across the face of Jupiter. The image above, by Gill, is what I think is the most dramatic. The other images are here, here, here, here, and here.

Oleksuik notes that the colors are not true, and are enhanced for drama. Also, the shadow in many of the images are much too large relative to the globe of Jupiter. The last link above gives a better sense of the true size of that shadow against Jupiter’s giant sphere. Io’s shadow only covers a tiny part of the surface. The reason it appears larger is that the whole image does not see the entire hemisphere.

Io volcano erupts like Ol’ Faithful

Having determined that Io’s largest volcano appears to erupt on a regularly schedule, scientists have predicted that a new eruption should occur sometime in the next week or so.

The volcano Loki is expected to erupt in mid-September, 2019, according to a poster by Planetary Science Institute Senior Scientist Julie Rathbun presented today.

“Loki is the largest and most powerful volcano on Io, so bright in the infrared that we can detect it using telescopes on the Earth,” Rathbun said. Based on more than 20 years of observations, Loki undergoes periodic brightenings when it erupts on a relatively regular schedule. In the 1990s, that schedule was approximately every 540 days. It currently appears to be approximately every 475 days. Rathbun discovered the 540-day periodicity, described in her 2002 paper “L. Loki, Io: A periodic volcano” that appeared in Geophysical Research Letters.

These same scientists successfully predicted Loki’s last eruption based on this data, but also warn that there is no guarantee the volcano will do what they say. As stock brokers are required to say, past performance is no guarantee of future results.

Scientists catch a big volcano eruption on Io

Scientists reviewing twenty year old data from the Galileo orbiter that studied Jupiter and its moons in the 1990s have identified the most intense volcanic eruption yet found on Io.

While looking through the NIMS temperature data, Davies and his colleagues spotted a brief but intense moment of high temperatures that cooled oddly quickly. This signal showed up as a spike in heat from a region in the southern hemisphere called Marduk Fluctus. First, the researchers saw a heat signal jump to 4–10 times higher than background, or relatively normal, levels. Then just a minute later, the signal dropped about 20%. Another minute later, the signal dropped another 75%. Twenty-three minutes later, the signal had plummeted to the equivalent of the background levels.

This signature resembled nothing Davies had seen before from Io. The lava flows and lava lakes are familiar: Their heat signals peter out slowly because as the surface of a lava flow cools, it creates a protective barrier of solid rock over a mushy, molten inside. Heat from magma underneath conducts through this newly formed crust and radiates from Io’s surface as it cools, which can take quite a long time.

This new heat signature, on the other hand, represents a process never before seen on Io, Davies said: something intense, powerful, and—most important—fast.

There’s only one likely explanation for what the instruments saw, explained Davies, whose volcanic expertise starts here on Earth. Large, violent eruptions like those seen at Stromboli are capable of spewing huge masses of tiny particles into the air, which cool quickly.

The article makes it sound like we’ve never seen this kind of eruption on Io before, which isn’t really true. Such eruptions have been imaged, but this is the first time that infrared data of their temperature spike was captured, thus confirming its nature.

Io’s atmosphere freezes and reinflates daily

New data from the ground-based Gemini telescope suggests that Io’s sulfur dioxide atmosphere freezes and then reinflates each time the moon flies through Jupiter’s shadow.

A study led by SwRI’s Constantine Tsang concluded that Io’s thin atmosphere, which consists primarily of sulfur dioxide (SO2) gas emitted from volcanoes, collapses as the SO2 freezes onto the surface as ice when Io is shaded by Jupiter. When the moon moves out of eclipse and ice warms, the atmosphere reforms through sublimation, where ice converts directly to gas.

The data is somewhat uncertain, however, as it based on only two observations.

The location of the volcanoes on Titan are not where scientists had expected them to be.

The uncertainty of science: The location of the volcanoes on Titan are not where scientists had expected them to be.

As Io moves closer to Jupiter, the planet’s powerful gravity pulls hard on the moon, deforming it. This force decreases as Io retreats, and the moon bounces back. This cycle of flexing creates friction in Io’s interior, which in turn generates enormous amounts of volcano-driving tidal heat. Common sense suggests that Io’s volcanoes would be located above the spots with the most dramatic internal heating. But Hamilton and his colleagues found that the volcanoes are significantly farther to the east than expected.

Many of the news headlines, including the article above, have trumpeted how the volcanoes on Io are in the wrong place. (See also this article.) Not. The theories were wrong, not the volcanoes. Nature does what it wants to do. It is our job to figure out why.

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