21.12.2021
NASA’s Juno Spacecraft ‘Hears’ Jupiter’s Moon
An audio track collected during Jupiter mission’s Ganymede flyby offers a dramatic ride-along. It is one of the highlights mission scientists shared in a briefing at American Geophysical Union Fall Meeting.
Sounds from a Ganymede flyby, magnetic fields, and remarkable comparisons between Jupiter and Earth’s oceans and atmospheres were discussed during a briefing today on NASA’s Juno mission to Jupiter at the American Geophysical Union Fall Meeting in New Orleans.
Juno Principal Investigator Scott Bolton of the Southwest Research Institute in San Antonio has debuted a 50-second audio track generated from data collected during the mission’s close flyby of the Jovian moon Ganymede on June 7, 2021. Juno’s Waves instrument, which tunes in to electric and magnetic radio waves produced in Jupiter’s magnetosphere, collected the data on those emissions. Their frequency was then shifted into the audio range to make the audio track.
“This soundtrack is just wild enough to make you feel as if you were riding along as Juno sails past Ganymede for the first time in more than two decades,” said Bolton. “If you listen closely, you can hear the abrupt change to higher frequencies around the midpoint of the recording, which represents entry into a different region in Ganymede's magnetosphere.”
Detailed analysis and modeling of the Waves data are ongoing. “It is possible the change in the frequency shortly after closest approach is due to passing from the nightside to the dayside of Ganymede,” said William Kurth of the University of Iowa in Iowa City, lead co-investigator for the Waves investigation.
At the time of Juno’s closest approach to Ganymede – during the mission’s 34th trip around Jupiter – the spacecraft was within 645 miles (1,038 kilometers) of the moon’s surface and traveling at a relative velocity of 41,600 mph (67,000 kph).
Magnetic Jupiter
Jack Connerney from NASA’s Goddard Space Flight Center in Greenbelt, Maryland, is the lead investigator with Juno’s magnetometer and is the mission’s deputy principal investigator. His team has produced the most detailed map ever obtained of Jupiter’s magnetic field.
Compiled from data collected from 32 orbits during Juno’s prime mission, the map provides new insights into the gas giant’s mysterious Great Blue Spot, a magnetic anomaly at the planet’s equator. Juno data indicates that a change in the gas giant’s magnetic field has occurred during the spacecraft’s five years in orbit, and that the Great Blue Spot is drifting eastward at a speed of about 2 inches (4 centimeters) per second relative to the rest of Jupiter’s interior, lapping the planet in about 350 years.
In contrast, the Great Red Spot – the long-lived atmospheric anticyclone just south of Jupiter’s equator – is drifting westward at a relatively rapid clip, circling the planet in about four-and-a-half years.
In addition, the new map shows that Jupiter’s zonal winds (jet streams that run east to west and west to east, giving Jupiter’s its distinctive banded appearance) are pulling the Great Blue Spot apart. This means that the zonal winds measured on the surface of the planet reach deep into the planet’s interior.
The new magnetic field map also allows Juno scientists to make comparisons with Earth’s magnetic field. The data suggests to the team that dynamo action – the mechanism by which a celestial body generates a magnetic field – in Jupiter’s interior occurs in metallic hydrogen, beneath a layer expressing “helium rain.”
Data Juno collects during its extended mission may further unravel the mysteries of the dynamo effect not only at Jupiter but those of other planets, including Earth.
Earth’s Oceans, Jupiter’s Atmosphere
Lia Siegelman, a physical oceanographer and postdoctoral fellow at Scripps Institution of Oceanography at the University of California, San Diego, decided to study the dynamics of Jupiter’s atmosphere after noticing that the cyclones at Jupiter’s pole appear to share similarities with ocean vortices she studied during her time as a doctoral student.
“When I saw the richness of the turbulence around the Jovian cyclones, with all the filaments and smaller eddies, it reminded me of the turbulence you see in the ocean around eddies,” said Siegelman. “These are especially evident in high-resolution satellite images of vortices in Earth’s oceans that are revealed by plankton blooms that act as tracers of the flow.”
The simplified model of Jupiter’s pole shows that geometric patterns of vortices, like those observed on Jupiter, spontaneously emerge, and survive forever. This means that the basic geometrical configuration of the planet allows these intriguing structures to form.
Although Jupiter’s energy system is on a scale much larger than Earth’s, understanding the dynamics of the Jovian atmosphere could help us understand the physical mechanisms at play on our own planet.
Arming Perseus
The Juno team has also released its latest image of Jupiter’s faint dust ring, taken from inside the ring looking out by the spacecraft’s Stellar Reference Unit navigation camera. The brightest of the thin bands and neighboring dark regions scene in the image are linked to dust generated by two of Jupiter’s small moons, Metis and Adrastea. The image also captures the arm of the constellation Perseus.
“It is breathtaking that we can gaze at these familiar constellations from a spacecraft a half-billion miles away,” said Heidi Becker, lead co-investigator of Juno’s Stellar Reference Unit instrument at NASA’s Jet Propulsion Laboratory in Pasadena. “But everything looks pretty much the same as when we appreciate them from our backyards here on Earth. It’s an awe-inspiring reminder of how small we are and how much there is left to explore.”
More About the Mission
JPL, a division of Caltech in Pasadena, California, manages the Juno mission for the principal investigator, Scott J. Bolton, of the Southwest Research Institute in San Antonio. Juno is part of NASA’s New Frontiers Program, which is managed at NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington. Lockheed Martin Space in Denver built and operates the spacecraft.
Quelle: NASA
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Update: 12.01.2022
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Juno solves mystery of what drives Jupiter's polar cyclones
Giant cyclones around Jupiter's poles are sustained by the same processes that drive the creation of ocean vortices on Earth.
A multitude of swirling clouds in Jupiter's dynamic North Temperate Belt is captured in this image from NASA's Juno spacecraft. (Image credit: NASA)
Giant cyclones around the poles of the solar system's largest planet are generated by the same forces that move water in Earth's oceans, a new study has found.
Jupiter's gargantuan polar cyclones, which are up to 620 miles (1,000 kilometers) across, were first spotted in 2016 by NASA's probe Juno. Since then, scientists have speculated that these storms are driven by convection, the process known from Earth in which hotter air expands and rises to higher, colder and denser altitudes. Until now, however, they couldn't prove the existence of this process on Jupiter.
Oceanographer Lia Siegelman, a postdoctoral researcher at Scripps Institution of Oceanography at the University of California San Diego, realized that those polar cyclones looked strikingly similar to ocean vortices that scientists study on our planet.
"When I saw the richness of the turbulence around the Jovian cyclones with all the filaments and smaller eddies, it reminded me of the turbulence you see in the ocean around eddies," Siegelman said in a statement. "These are especially evident on high-resolution satellite images of plankton blooms, for example."
Siegelman and her colleagues analyzed a series of images of the cyclonessurrounding Jupiter's north pole captured in the infrared wavelengths, those that reveal the heat emitted by an object. The researchers used the same methodology that helps scientists study large-scale flows of air and water in Earth's atmosphere and oceans.
The analysis enabled the team to calculate the direction and speed of local winds and to track the movement of clouds. The researchers were able to distinguish areas with thin cloud cover, where they could see deeper into Jupiter's atmosphere, and those obscured by a thick blanket of fog.
Algal blooms in the Pacific Ocean captured by the European Sentinel 2 Earth observation satellite. (Image credit: Copernicus)
The analysis proved that rising hot air transports energy within the atmosphere and feeds the clouds as they grow into large-scale cyclones, such as those observed around the poles.
"To be able to study a planet that is so far away and find physics that apply there is fascinating," said Siegelman.
She added that just as the science of Earth's oceans is now helping to unlock the mysteries of Jupiter's atmosphere, the new findings could in turn help shed new light on those large-scale processes on Earth.
For example, the physical mechanism at play on Jupiter could reveal routes of energy exchange that could also exist on our planet that scientists have not yet identified.
Juno is the first spacecraft to photograph Jupiter's poles, as previous probes, like the 1990s Galileo mission, explored the giant planet by orbiting along its equator. The Juno spacecraft found eight cyclones around the planet's north pole and five in the south, all of which are still present more than five years after their discovery.
The study was published on Monday (Jan. 10) in the journal Nature Physics.
Quelle: SC
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Update: 9.03.2022
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Jupiter's big moon Ganymede casts giant shadow in stunning Juno photo by citizen scientist
The fresh image came from a May 2019 flyby of the NASA spacecraft.
(Image credit: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill)
A powerful new picture of Jupiter posted by a citizen scientist shows the planet looming large with the shadow of its biggest moon Ganymede blanketing its clouds.
The image comes from Kevin M. Gill, who posted copies on Twitter and Flickr after analyzing data from the Juno spacecraft's 20th close flyby of May 2019.
Like many other NASA missions, Juno officials regularly release raw images of what the spacecraft is examining, allowing other people to use the imagery with credit. The mission also has a dedicated imager for citizen scientist requests, called JunoCam.
Juno arrived at Jupiter in 2016 on a greater mission to better measure and understand the atmosphere of Jupiter, including its shrinking Great Red Spot, complex storm systems and many bands of clouds.
The hope is the insights the mission generates can help scientists understand how large planets work more generally, including distant exoplanets that are difficult for telescopes to gain much detail about.
A backlit image of Jupiter captured by Juno. (Image credit: NASA/JPL-Caltech/SwRI/MSSS Image processing by Kevin M. Gill © CC BY)
NASA suggests that during this 20th flyby, the spacecraft got at least as closeas 9,200 miles (14,800 kilometers) above the cloud tops of the giant planet. Juno can only perform such maneuvers briefly due to the intense radiation at Jupiter.
The spacecraft has so far outlasted the radiation in both its primary mission and its first extended mission. Juno is now working on its second extended mission to peer far into Jupiter's clouds, using a polar-orbiting view that no previous spacecraft was able to use.
Coincidentally, NASA released images of both Jupiter and Ganymede last month from Juno, with Gill being involved in creating the Jupiter image. The rugged Ganymede surface was visible during a June 2021 pass when Juno flew only 650 miles (1,046 kilometers) above Ganymede's surface. Officials also released Gill's backlit view of Jupiter, based on data Juno took during Juno's 39th close pass of Jupiter on Jan. 12.
Quelle: SC
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Update: 21.03.2022
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NASA spacecraft snaps gorgeous new photo of Jupiter's moons Io and Europa
NASA's Juno spacecraft flew close to Jupiter on Jan. 12, capturing a stunning new view of the planet and two of its moons, lo and Europa.
Taken during Juno's 39th close flyby of Jupiter on Jan. 12, 2022, this stunning view captures two of the planet's moons: Io (left) and Europa (right). (Image credit: NASA/JPL-Caltech/SwRI/MSSS/processing by AndreaLuck CC BY)
NASA's Juno spacecraft beamed back stunning new photos of Jupiter's moons, Io and Europa.
Juno's latest view of the two moons was captured during the spacecraft's 39th close flyby of Jupiter on Jan. 12. At the time, the spacecraft was about 38,000 miles (61,000 kilometers) above Jupiter's cloud tops, at a latitude of about 52 degrees south.
The new photo, which NASA shared on March 16, offers a stunning view of Jupiter's southern hemisphere, with two of its many moons to the right of the frame. A zoomed in view that the agency also shared brings the moons into clear view, with Io on the left and Europa on the right.
Jupiter's moon Io is the most volcanic body in the solar system. Hundreds of volcanoes dot its surface, some of them spewing sulfurous plumes hundreds of miles high.
Conversely, Europa, the smallest of Jupiter's four giant Galilean moons, has an icy surface, beneath which lies a global ocean of liquid water, scientists believe. Previous observations have found evidence of possible water plumes jetting from the Europa's south polar region, suggesting that there is water in the moon's subsurface ocean breaking out through cracks in the icy crust.
The Juno spacecraft is expected to make its closest fly-by of Europa later this year, in September. During this fly-by, the probe will use several of its scientific instruments to study Europa in greater detail and capture even more stunning views of the mysterious moon.
The full view of Jupiter, Io and Europa captured by the Juno spacecraft on Jan. 12, 2022. (Image credit: NASA/JPL-Caltech/SwRI/MSSS/processing by AndreaLuck CC BY)
The Juno mission will also make close approaches to lo in late 2023 and early 2024, according to the NASA statement. The mission is currently expected to end in September 2025.
Two key spacecraft will soon follow in Juno's wake designed to focus exclusively on understanding the giant's moons: NASA's Europa Clipper mission and the European Space Agency's Jupiter Icy Moons Explorer (JUICE).
The new Jupiter photo was processed by citizen scientist Andrea Luck, using raw data from the JunoCam instrument. JunoCam's raw images are available onlineto the public; members of the community can also suggest features on Jupiter for the camera to photograph.
Quelle: SC
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Update: 23.03.2022
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NASA flyby of Jupiter's big moon Ganymede reveals auroras and huge unknown craters
The Jupiter explorer Juno discovered previously unknown craters on the surface of the gas giant's largest moon Ganymede. (Image credit: Caltech/SwRI/MSSS/Kalleheikki Kannisto)
After a NASA mission passed within 620 miles (1,000 kilometers) of Jupiter's largest moon Ganymede in June 2021, scientists are still decoding what the encounter can teach us about the strange world.
Two missions have previously imaged Ganymede, the largest moon in the solar system, Voyager 1 mission in 1979 and the Galileo spacecraft in the mid 1990s. Some of those images, however, were taken at a less than ideal angle, leaving large blank spots that scientists knew nothing about; technology has also improved dramatically since those missions launched. So scientists were thrilled when NASA's Jupiter explorer Juno revealed the moon's crater-covered surface in the greatest detail ever and spotted shimmering auroras stretching between Ganymede's poles and equator.
These images outlined a plethora of new features on Ganymede's surface, including impact craters as large as 60 miles (100 kilometer) wide, Goeffrey Collins, a geologist at Wheaton College in Massachusetts, said at the Lunar and Planetary Science Conference that took place March 7 to 11 in Texas.
"We missed some really big impact craters that we just couldn't see in the Voyager data," Collins said. "This should be a cautionary tale for trying to map things off just one image with one lighting angle, one viewing angle. We missed this big 100 kilometer crater that's really obvious in the JunoCam data. And another, a little less obvious crater that is about 110 kilometers [68 miles] wide."
The images also revealed several smaller craters, 25 to 30 miles (40 to 50 km) wide, and multiple features that the scientists believe might be a result of Ganymede's volcanic activity.
"We have found caldera-like features, similar to those that we have seen previously in other parts of Ganymede," said Collins. Calderas are volcanic craters that in the case of Ganymede were likely created by cryovolcanoes that spout frozen water and gas from the moon's interior.
The number of these features seen in the Juno images suggests a much more intense volcanic activity on the moon than scientists expected previously.
"This actually bumps up the number of total caldera-like features that we found on all of Ganymede by 30%," said Collins. "It definitely makes us think that we have undercounted these so far. There might be a lot more of these to be found on Ganymede as we get new data."
Not only is Ganymede the largest moon in the entire solar system, 26% larger than the planet Mercury, it is also the only moon that we know has its own magnetic field. The variations in this magnetic field led scientists to conclude that the moon must have a massive underground ocean of salty water, which is up to 60 miles deep and hidden underneath a 95-mile-thick (150 km) crust of ice and rock. The ocean makes Ganymede a prime candidate for the existence of primitive forms of life.
Orbiting 665,000 miles (1.07 million km) away from the gas giant Jupiter, Ganymede is embedded within Jupiter's magnetic field and enormous gravity, which attracts passing asteroids and comets.
The interplay between the magnetic fields of Ganymede and Jupiter gives rise to bright auroras on the former, the only such displays ever observed on a moon. Ganymede's auroras were discovered in images from the Hubble Space Telescope, but the recent Juno flyby enabled scientists to gain more insights into these shimmering spectacles.
"We were now able to see the exact locations of the [auroral] emissions," Pippa Molyneaux, a researcher at the Southwest Research Institute in San Antonio, Texas, said at the conference. "We were able to see the latitudinal extent of the aurora for the first time and we see that there are very sharp boundaries at the poleward edges of both [aurora] ovals, whereas when you move towards the equator, the emissions fall off more gradually, so future models would have to explain this."
Ganymede will be the main target of the upcoming European Jupiter Icy Moons Explorer (JUICE), which is expected to launch next year.
Quelle: SC
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Update: 25.04.2022
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Shadow of Jupiter's largest moon looms in magnificent new Juno photo
NASA's Juno spacecraft imaged Jupiter and Ganymede during the mission's 40th close pass by the giant planet on Feb. 25, 2022. (Image credit: Image data: NASA/JPL-Caltech/SwRI/MSSS Image processing by Thomas Thomopoulos © CC BY)
Giant Jupiter and the shadow of its biggest moon, Ganymede, dominate the view in this latest image from the system based on a NASA spacecraft's data.
NASA's Juno mission whizzed close by the radiation-spewing planet for the 40th time on Feb. 25, with the resulting raw images of the encounter beamed home to Earth. There, citizen scientist Thomas Thomopoulos created this stunning view based on what was seen by the JunoCam instrument.
Juno was flying roughly 44,000 miles (71,000 kilometers) above Jupiter's cloud tops during the encounter, which is roughly 15 times closer than Ganymede's orbital distance of 666,000 miles (1.1 million kilometers), NASA stated.
If an observer could brave the radiation to float within the oval seen in the picture, NASA added, that person would experience a total eclipse of the sun. "Total eclipses are more common on Jupiter than Earth," the agency said, noting the planet hosts four large moons (Ganymede, Io, Europa and Callisto) that orbit closer to the plane of Jupiter than our own, singular moon.
JunoCam, the agency said, "captured this image from very close to Jupiter, making Ganymede's shadow appear especially large."
The Juno spacecraft is on a long-term mission to understand the weather and the dynamics of Jupiter, the largest planet of our solar system. Studying this planet from up close allows scientists also to get a sense of how large exoplanets may behave in other solar systems.
Juno remains in good health amid an extended mission, but will have a limited lifespan due to the amount of radiation it is facing, NASA has warned. But space scientists have big plans for the icy moons of Jupiter in the 2030s, including visits from NASA's Europa Clipper and the European Space Agency's Jupiter Icy Moons Explorer.
Quelle: SC
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Update: 4.06.2022
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Jupiter is a whirling world in stunning (and woozy) footage from Juno spacecraft
The spacecraft passed within 2,050 miles (3,300 kilometers) of the colorful cloud tops on April 9.
Hang on tight as you watch this new footage of Jupiter.
This sped-up view shows the perspective of NASA's Juno spacecraft as it flew just 2,050 miles (3,300 kilometers) above the gas giant's cloud tops on April 9. This was Juno's 41st flyby above the radiation-spewing planet, during which the spacecraft soared at a top speed of 131,000 mph (210,000 km/h) relative to Jupiter.
"Citizen scientist Andrea Luck created this animated sequence using raw JunoCam image data," NASA officials wrote in a statement(opens in new tab) Friday (May 27).
That's more than seven times faster than the speed of the International Space Station orbits Earth and about five times faster than the crewed Apollo missionswere traveling as they left Earth for the moon, NASA officials said in the statement.
The colorful imagery was created from the JunoCam instrument's raw images, which officials upload to an image processing gallery that allows citizen scientists to add their insights to the raw data.
While Juno's initial main target has been Jupiter, in January 2021 NASA authorized an extension of the mission's mandate to focus a little more closely on the planet's four large moons, especially Ganymede, Europa and Io. Juno will run until September 2025, assuming it remains in good health.
"With the extended mission, we will answer fundamental questions that arose during Juno's prime mission while reaching beyond the planet to explore Jupiter’s ring system and Galilean satellites," principal investigator Scott Bolton, of the Southwest Research Institute in San Antonio, said in a NASA statement(opens in new tab)when the extension was announced.
Radiation will likely be the mission's main threat as it attempts to continue its work for the next three years, but as long as Juno is active, it will serve as a scout for future missions at Jupiter, the largest planet in the solar system.
NASA's Juno spacecraft imaged Jupiter and Ganymede's shadow during the mission's 40th close pass by the giant planet on Feb. 25, 2022. (Image credit: Image data: NASA/JPL-Caltech/SwRI/MSSS Image processing by Thomas Thomopoulos © CC BY)
In the 2030s, for example, NASA's Europa Clipper and the European Space Agency's JUICE mission (Jupiter Icy Moons Explorer) plan to visit Jupiter moons directly.
The new James Webb Space Telescopewill also examine the giant planet from afar during its forthcoming Cycle 1 set of observations. Webb's work will add to years of data collected under the Hubble Space Telescope's Outer Planet Atmospheres Legacy program, which seeks to study the gas giants of the solar system at least once every Earth year.
Quelle: SC
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Update: 29.07.2022
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The north pole of Jupiter has mesmerizing storms, new Juno images reveal
Scientists are trying to figure out what gives those storms their color and shape.
Storms swirl around Jupiter's north pole in images captured by NASA's Juno mission during its flyby in July 2022.(Image credit: NASA/JPL-Caltech/SwRI/MSSS Image processing by Brian Swift )
Powerful storms around the north pole of Jupiter swirl in stunning new images captured by NASA's Juno probe during its close approach to the giant planet on July 5.
The storms reach depths of over 30 miles (50 kilometers) in the turbulentatmosphere of Jupiter and are hundreds of miles wide, NASA said in a statement(opens in new tab). Scientists are studying these storms to understand what drives their formation and gives them their striking and unique features.
Past observations of Jupiter have shown that these cyclones vary in color based on the direction in which they spin, as well as on their location. For example, storms that spin counter-clockwise in Jupiter's northern hemisphere and those that spin clockwise in the southern hemisphere have distinctly different shapes and colors to those spinning clockwise in the north and counterclockwise in the south.
Juno, which launched in 2011 and reached the gas giant five years later, took the images during its 43rd close flyby at Jupiter on July 5, NASA said in the statement. The probe circles Jupiter in a highly elliptical orbit, completing one lap every 43 days. At its closest, Juno approaches within about 3,100 miles (5,000 kilometers) of the tops of Jupiter's clouds. This particular image was taken when the probe was at a distance of about 15,600 miles (25,100 kilometers) from the planet.
The Juno mission, originally planned to retire in 2021, was extended last year to at least 2025. During its remaining lifetime, the probe will continue its focus on Jupiter's fascinating atmosphere, and will also study the planet's mysterious moons Ganymede, Europa, and Io, some of which may host microbial life.
Powerful storms around the north pole of Jupiter captured by NASA's Juno mission during a recent flyby. (Image credit: NASA/JPL-Caltech/SwRI/MSSS Image processing by Brian Swift )
In the meantime, NASA asks space enthusiasts and citizen scientists to help categorize the images of storms and other atmospheric phenomena captured by Juno's JunoCam instrument as part of the Jovian Vortex Hunter(opens in new tab) project. Anyone with access to a cellphone or a laptop can contribute to the analysis. So far, over 2,400 volunteers made classifications of over 375,000 images as part of the project.
Quelle: SC
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Update: 4.09.2022
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NASA’s Juno Mission Reveals Jupiter’s Complex Colors
NASA’s Juno spacecraft observed the complex colors and structure of Jupiter’s clouds as it completed its 43rd close flyby of the giant planet on July 5, 2022.
Citizen scientist Björn Jónsson created these two images using raw data from the JunoCam instrument aboard the spacecraft. At the time the raw image was taken, Juno was about 3,300 miles (5,300 kilometers) above Jupiter’s cloud tops, at a latitude of about 50 degrees. North is up. At that moment, the spacecraft was traveling at about 130,000 mph (209,000 kilometers per hour) relative to the planet.
The first image (left) was processed to portray the approximate colors that the human eye would see from Juno’s vantage point. The second image (right) comes from the same raw data, but in this case Jónsson digitally processed it to increase both the color saturation and contrast to sharpen small-scale features and to reduce compression artifacts and noise that typically appear in raw images. This clearly reveals some of the most intriguing aspects of Jupiter’s atmosphere, including color variation that results from differing chemical composition, the three-dimensional nature of Jupiter’s swirling vortices, and the small, bright “pop-up” clouds that form in the higher parts of the atmosphere.
JunoCam's raw images are available for the public to peruse and process into image products at https://missionjuno.swri.edu/junocam/processing. More information about NASA citizen science can be found at https://science.nasa.gov/citizenscience and https://www.nasa.gov/solve/opportunities/citizenscience.
More information about Juno is at https://www.nasa.gov/juno and https://missionjuno.swri.edu. For more about this finding and other science results, see https://www.missionjuno.swri.edu/science-findings.
Quelle: NASA
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Update: 24.09.2022
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NASA’s Juno Will Perform Close Flyby of Jupiter’s Icy Moon Europa
NASA's Juno spacecraft made a distant encounter with Jupiter's moon Europa on its 37th close pass by Jupiter. This image from the spacecraft's JunoCam was taken at a distance of about 51,000 miles (82,000 kilometers). Color and reflectance variations across Europa's regions can be seen in this JunoCam image. Although the resolution of the images is just 50 to 60 km per pixel, the data fills in a previously un-imaged area around the north pole near the center of the image.
As Juno's orbit evolves, it is crossing the orbits of the Galilean moons. The next encounter with Europa will take place in February 2022, at a distance of about 29,000 miles (47,000 km). In late September 2022, Juno will swoop to just 221 miles (355 kilometers) above Europa's surface.
As the spacecraft makes a close approach of the moon, it is expected to provide valuable science – and remarkable imagery – for NASA’s upcoming Europa Clipper mission.
On Thursday, Sept. 29, at 2:36 a.m. PDT (5:36 a.m. EDT), NASA’s Juno spacecraft will come within 222 miles (358 kilometers) of the surface of Jupiter’s ice-covered moon, Europa. The solar-powered spacecraft is expected to obtain some of the highest-resolution images ever taken of portions of Europa’s surface, as well as collect valuable data on the moon’s interior, surface composition, and ionosphere, along with its interaction with Jupiter’s magnetosphere.
Such information could benefit future missions, including the agency’s Europa Clipper, which is set to launch in 2024 to study the icy moon. “Europa is such an intriguing Jovian moon, it is the focus of its own future NASA mission,” said Juno Principal Investigator Scott Bolton of the Southwest Research Institute in San Antonio. “We’re happy to provide data that may help the Europa Clipper team with mission planning, as well as provide new scientific insights into this icy world.”
Juno’s extended mission includes flybys of the moons Ganymede, Europa, and Io. This graphic depicts the spacecraft’s orbits of Jupiter – labeled “PJ” for perijove, or point of closest approach to the planet – from its prime mission in gray to the 42 orbits of its extended mission in shades of blue and purple.
With an equatorial diameter of 1,940 miles (3,100 kilometers), Europa is about 90% the size of Earth’s Moon. Scientists think a salty ocean lies below a miles-thick ice shell, sparking questions about potential conditions capable of supporting life underneath Europa’s surface.
The close flyby will modify Juno’s trajectory, reducing the time it takes to orbit Jupiter from 43 to 38 days. It will be the closest a NASA spacecraft has approached Europa since Galileo came within 218 miles (351 kilometers) on Jan. 3, 2000. In addition, this flyby marks the second encounter with a Galilean moonduring Juno’s extended mission. The mission explored Ganymede in June 2021 and plans to make close approaches of Io in 2023 and 2024.
Data collection will begin an hour prior to closest approach, when the spacecraft is 51,820 miles (83,397 kilometers) from Europa.
“The relative velocity between spacecraft and moon will be 14.7 miles per second (23.6 kilometers per second), so we are screaming by pretty fast,” said John Bordi, Juno deputy mission manager at JPL. “All steps have to go like clockwork to successfully acquire our planned data, because soon after the flyby is complete, the spacecraft needs to be reoriented for our upcoming close approach of Jupiter, which happens only 7 ½ hours later.”
Find out where Juno is right now with NASA’s interactive Eyes on the Solar System. With its three giant blades stretching out some 66 feet (20 meters), the spacecraft is a dynamic engineering marvel, spinning to keep itself stable as it makes oval-shaped orbits around Jupiter. Credit: NASA/JPL-Caltech
The spacecraft’s full suite of instruments and sensors will be activated for the Europa encounter. Juno’s Jupiter Energetic-Particle Detector Instrument (JEDI) and its medium-gain (X-band) radio antenna will collect data on Europa’s ionosphere. Its Waves, Jovian Auroral Distributions Experiment (JADE), and Magnetometer (MAG) experiments will measure plasma in the moon’s wake as Juno explores Europa’s interaction with Jupiter’s magnetosphere.
MAG and Waves will also search for possible water plumesabove Europa’s surface. “We have the right equipment to do the job, but to capture a plume will require a lot of luck,” said Bolton. “We have to be at the right place at just the right time, but if we are so fortunate, it’s a home run for sure.”
Inside and Out
Juno’s Microwave Radiometer (MWR) will peer into Europa’s water-ice crust, obtaining data on its composition and temperature. This is the first time such data will have been collected to study the moon’s icy shell.
In addition, the mission expects to take four visible-light images of the moon with JunoCam (a public-engagement camera) during the flyby. The Juno science team will compare them to images from previous missions, looking for changes in Europa’s surface features that might have occurred over the past two decades. These visible-light images will have an expected resolution better than 0.6 miles (1 kilometer) per pixel.
Although Juno will be in Europa’s shadow when closest to the moon, Jupiter’s atmosphere will reflect enough sunlight for Juno’s visible-light imagers to collect data. Designed to take images of star fields and search for bright stars with known positions to help Juno get its bearings, the mission’s star camera (called the Stellar Reference Unit) will take a high-resolution black-and-white image of Europa’s surface. Meanwhile, the Jovian Infrared Auroral Mapper (JIRAM) will attempt to collect infrared images of its surface.
Quelle: NASA