Juno Isn’t Exactly Where it’s Supposed To Be. The Flyby Anomaly is Back, But Why Does it Happen?

In the early 1960s, scientists developed the gravity-assist method, where a spacecraft would conduct a flyby of a major body in order to increase its speed. Many notable missions have used this technique, including the Pioneer, Voyager, Galileo, Cassini, and New Horizons missions. In the course of many of these flybys, scientists have noted an anomaly where the increase in the spacecraft’s speed did not accord with orbital models.

This has come to be known as the “flyby anomaly”, which has endured despite decades of study and resisted all previous attempts at explanation. To address this, a team of researchers from the University Institute of Multidisciplinary Mathematics at the Universitat Politecnica de Valencia have developed a new orbital model based on the maneuvers conducted by the Juno probe.

The study, which recently appeared online under the title “A Possible Flyby Anomaly for Juno at Jupiter“, was conducted by Luis Acedo, Pedro Piqueras and Jose A. Morano. Together, they examined the possible causes of the so-called “flyby anomaly” using the perijove orbit of the Juno probe. Based on Juno’s many pole-to-pole orbits, they not only determined that it too experienced an anomaly, but offered a possible explanation for this.

Artist’s impression of the Pioneer 10 probe, launched in 1972 and now making its way out towards the star Aldebaran. Credit: NASA

To break it down, the speed of a spacecraft is determined by measuring the Doppler shift of radio signals from the spacecraft to the antennas on the Deep Space Network (DSN). During the 1970s when the Pioneer 10 and 11 probes were launched, visiting Jupiter and Saturn before heading off towards the edge of the Solar System, these probes both experienced something strange as they passed between 20 to 70 AU (Uranus to the Kuiper Belt) from the Sun.

Basically, the probes were both 386,000 km (240,000 mi) farther from where existing models predicted they would be. This came to be known as the “Pioneer anomaly“, which became common lore within the space physics community. While the Pioneer anomaly was resolved, the same phenomena has occurred many times since then with subsequent missions. As Dr. Acebo told Universe Today via email:

“The “flyby anomaly” is a problem in astrodynamics discovered by a JPL’s team of researchers lead by John Anderson in the early 90s. When they tried to fit the whole trajectory of the Galileo spacecraft as it approached the Earth on December, 8th, 1990, they found that this only can be done by considering that the ingoing and outgoing pieces of the trajectory correspond to asymptotic velocities that differ in 3.92 mm/s from what is expected in theory.

“The effect appears both in the Doppler data and in the ranging data, so it is not a consequence of the measurement technique. Later on, it has also been found in several flybys performed by Galileo again in 1992, the NEAR [Near Earth Asteroid Rendezvous mission] in 1998, Cassini in 1999 or Rosetta and Messenger in 2005. The largest discrepancy was found for the NEAR (around 13 mm/s) and this is attributed to the very close distance of 532 Km to the surface of the Earth at the perigee.”

NASA’s Juno spacecraft launched on August 6, 2011 and should arrive at Jupiter on July 4, 2016. Credit: NASA / JPL

Another mystery is that while in some cases the anomaly was clear, in others it was on the threshold of detectability or simply absent – as was the case with Juno‘s flyby of Earth in October of 2013. The absence of any convincing explanation has led to a number of explanations, ranging from the influence or dark matter and tidal effects to extensions of General Relativity and the existence of new physics.

However, none of these have produced a substantive explanation that could account for flyby anomalies. To address this, Acedo and his colleagues sought to create a model that was optimized for the Juno mission while at perijove – i.e. the point in the probe’s orbit where it is closest to Jupiter’s center. As Acedo explained:

After the arrival of Juno at Jupiter on July, 4th, 2016, we had the idea of developing our independent orbital model to compare with the fitted trajectories that were being calculated by the JPL team at NASA. After all, Juno is performing very close flybys of Jupiter because the altitude over the top clouds (around 4000 km) is a small fraction of the planet’s radius. So, we expected to find the anomaly here.  This would be an interesting addition to our knowledge of this effect because it would prove that it is not only a particular problem with Earth flybys but that it is universal.”

Their model took into account the tidal forces exerted by the Sun and by Jupiter’s larger satellites – Io, Europa, Ganymede and Callisto – and also the contributions of the known zonal harmonics. They also accounted for Jupiter’s multipolar fields, which are the result of the planet oblate shape, since these play a far more important role than tidal forces as Juno reaches perijove.

Illustration of NASA’s Juno spacecraft firing its main engine to slow down and go into orbit around Jupiter. Lockheed Martin built the Juno spacecraft for NASA’s Jet Propulsion Laboratory. Credit: NASA/Lockheed Martin

In the end, they determined that an anomaly could also be present during the Juno flybys of Jupiter. They also noted a significant radial component in this anomaly, one which decayed the farther the probe got from the center of Jupiter. As Acebo explained:

“Our conclusion is that an anomalous acceleration is also acting upon the Juno spacecraft in the vicinity of the perijove (in this case, the asymptotic velocity is not a useful concept because the trajectory is closed). This acceleration is almost one hundred times larger than the typical anomalous accelerations responsible for the anomaly in the case of the Earth flybys. This was already expected in connection with Anderson et al.’s initial intuition that the effect increases with the angular rotational velocity of the planet (a period of 9.8 hours for Jupiter vs the 24 hours of the Earth), the radius of the planet and probably its mass.”

They also determined that this anomaly appears to be dependent on the ratio between the spacecraft’s radial velocity and the speed of light, and that this decreases very fast as the craft’s altitude over Jupiter’s clouds changes. These issues were not predicted by General Relativity, so there is a chance that flyby anomalies are the result of novel gravitational phenomena – or perhaps, a more conventional effect that has been overlooked.

In the end, the model that resulted from their calculations accorded closely with telemetry data provided by the Juno mission, though questions remain. Further research is necessary because the pattern of the anomaly seems very complex and a single orbit (or a sequence of similar orbits as in the case of Juno) cannot map the whole field,” said Acebo. “A dedicated mission is required but financial cuts and limited interest in experimental gravity may prevent us to see this mission in the near future.”

It is a testament to the complexities of physics that even after sixty years of space exploration – and one hundred years since General Relativity was first proposed – that we are still refining our models. Perhaps someday we will find there are no mysteries left to solve, and the Universe will make perfect sense to us. What a terrible day that will be!

Further Reading: Earth and Planetary Astrophysics

That’s Strange. Jupiter’s Northern and Southern Auroras Pulse Independently

In addition to being the largest and most massive planet in our Solar system, Jupiter is also one of its more mysterious bodies. This is certainly apparent when it comes to Jupiter’s powerful auroras, which are similar in some ways to those on Earth. In recent years, astronomers have sought to study patterns in Jupiter’s atmosphere and magnetosphere to explain how aurora activity on this planet works..

For instance, an international team led by researchers from University College London recently combined data from the Juno probe with X-ray observations to discern something interesting about Jupiter’s northern and southern auroras. According to their study, which was published  in the current issue of the scientific journal Nature – Jupiter’s intense, Jupiter’s X-ray auroras have been found to pulsate independently of each other.

The study, titled “The independent pulsations of Jupiter’s northern and southern X-ray auroras“, was led by William Richard Dunn – a physicist with the Mullard Space Science Laboratory and The Center for Planetary Science at UCL . The team also consisted of researchers from the Harvard-Smithsonian Center for Astrophysics (CfA), the Southwest Research Institute (SwRI), NASA’s Marshall Space Flight Center, the Jet Propulsion Laboratory, and multiple research institutions.

Jupiter has spectacular aurora, such as this view captured by the Hubble Space Telescope. Credit: NASA, ESA, and J. Nichols (University of Leicester)

As already noted, Jupiter’s auroras are somewhat similar to Earth’s, in that they are also the result of charged particles from the Sun (aka. “solar wind”) interacting with Jupiter’s magnetic field. Because of the way Jupiter and Earth’s magnetic fields are structured, these particles are channeled to the northern and southern polar regions, where they become ionized in the atmosphere. This results in a beautiful light display that can be seen from space.

In the past, auroras have been spotted around Jupiter’s poles by NASA’s Chandra X-ray Observatory and by the Hubble Space Telescope. Investigating this phenomena and the mechanisms behind it has also been one of the goals of the Juno mission, which is currently in an ideal position to study Jupiter’s poles. With every orbit the probe makes, it passes from one of Jupiter’s poles to the other – a maneuver known as a perijove.

For the sake of their study, Dr. Dunn and his team were forced to consult data from the ESA’s XMM-Newton and NASA’s Chandra X-ray observatories. This is due to the fact that while it has already acquired magnificent images and data on Jupiter’s atmosphere, the Juno probe does not have an X-ray instrument aboard. Once they examined the X-ray data, Dr. Dunn and his team noticed a difference between Jupiter’s northern and southern auroras.

Whereas the X-ray emissions at the north pole were erratic, increasing and decreasing in brightness, the ones at the south pole consistently pulsed once every 11 minutes. Basically, the auroras happened independently of each other, which is different from how auroras on Earth behave – i.e. mirroring each other in terms of their activity. As Dr. Dunn explained in a recent UCL press release:

“We didn’t expect to see Jupiter’s X-ray hot spots pulsing independently as we thought their activity would be coordinated through the planet’s magnetic field. We need to study this further to develop ideas for how Jupiter produces its X-ray aurora and NASA’s Juno mission is really important for this.”

The X-ray observations were conducted between May and June of 2016 and March of 2017. Using these, the team produced maps of Jupiter’s X-ray emissions and identified hot spots at each pole. The hot spots cover an area that is larger than the surface area of Earth. By studying them, Dr. Dunn and his colleagues were able to identify patterns of behavior which indicated that they behaved differently from each other.

Naturally, the team was left wondering what could account for this. One possibility they suggest is that Jupiter’s magnetic field lines vibrate, producing waves that carry charged particles towards the poles. The speed and direction of these particles could be subject to change over time, causing them to eventually collide with Jupiter’s atmosphere and generate X-ray pulses.

As Dr Licia Ray, a physicist from Lancaster University and a co-author on the paper, explained:

“The behavior of Jupiter’s X-ray hot spots raises important questions about what processes produce these auroras. We know that a combination of solar wind ions and ions of Oxygen and Sulfur, originally from volcanic explosions from Jupiter’s moon, Io, are involved. However, their relative importance in producing the X-ray emissions is unclear.”

And as Graziella Branduardi-Raymont- a professor from UCL’s Space & Climate Physics department and another co-author on the study – indicated, this research owes its existence to multiple missions. However, it was the perfectly-timed nature of the Juno mission, which has been in operation around Jupiter since July 5th, 2016, that made this study possible.

Composite images from the Chandra X-Ray Observatory and the Hubble Space Telescope show the hyper-energetic x-ray auroras at Jupiter. The image on the left is of the auroras when the coronal mass ejection reached Jupiter, the image on the right is when the auroras subsided. The auroras were triggered by a coronal mass ejection from the Sun that reached the planet in 2011. Image: X-ray: NASA/CXC/UCL/W.Dunn et al, Optical: NASA/STScI
Composite images from the Chandra X-Ray Observatory and the Hubble Space Telescope show the hyper-energetic x-ray auroras at Jupiter. Credit: X-ray: NASA/CXC/UCL/STScI/W.Dunn et al.

“What I find particularly captivating in these observations, especially at the time when Juno is making measurements in situ, is the fact that we are able to see both of Jupiter’s poles at once, a rare opportunity that last occurred ten years ago,” he said. “Comparing the behaviours at the two poles allows us to learn much more of the complex magnetic interactions going on in the planet’s environment.”

Looking ahead, Dr. Dunn and his team hope to combine X-ray data from XMM-Newton and Chandra with data collected by Juno in order to gain a better understanding of how X-ray auroras are produced. The team also hopes to keep tracking the activity of Jupiter’s poles for the next two years using X-ray data in conjunction with Juno. In the end, they hope to see if these auroras are commonplace or an unusual event.

“If we can start to connect the X-ray signatures with the physical processes that produce them, then we can use those signatures to understand other bodies across the Universe such as brown dwarfs, exoplanets or maybe even neutron stars,” said Dr. Dunn. “It is a very powerful and important step towards understanding X-rays throughout the Universe and one that we only have while Juno is conducting measurements simultaneously with Chandra and XMM-Newton.”

In the coming decade, the ESA’s proposed JUpiter ICy moons Explorer (JUICE) probe is also expected to provide valuable information on Jupiter’s atmosphere and magnetosphere. Once it arrives in the Jovian system in 2029, it too will observe the planet’s auroras, mainly so that it can study the effect these have on the Galilean Moons (Io, Europa, Ganymede and Callisto).

Further Reading: UCL, ESA, Nature Astronomy

Juno Finds that Jupiter’s Gravitational Field is “Askew”

Since it established orbit around Jupiter in July of 2016, the Juno mission has been sending back vital information about the gas giant’s atmosphere, magnetic field and weather patterns. With every passing orbit – known as perijoves, which take place every 53 days – the probe has revealed more interesting things about Jupiter, which scientists will rely on to learn more about its formation and evolution.

During its latest pass, the probe managed to provide the most detailed look to date of the planet’s interior. In so doing, it learned that Jupiter’s powerful magnetic field is askew, with different patterns in it’s northern and southern hemispheres. These findings were shared on Wednesday. Oct. 18th, at the 48th Meeting of the American Astronomical Society’s Division of Planetary Sciencejs in Provo, Utah.

Ever since astronomers began observing Jupiter with powerful telescopes, they have been aware of its swirling, banded appearance. These colorful stripes of orange, brown and white are the result of Jupiter’s atmospheric composition, which is largely made up of hydrogen and helium but also contains ammonia crystals and compounds that change color when exposed to sunlight (aka. chromofores).

Illustration of NASA’s Juno spacecraft firing its main engine to slow down and go into orbit around Jupiter. Credit: NASA/Lockheed Martin

Until now, researchers have been unclear as to whether or not these bands are confined to a shallow layer of the atmosphere or reach deep into the interior of the planet. Answering this question is one of the main goals of the Juno mission, which has been studying Jupiter’s magnetic field to see how it’s interior atmosphere works. Based on the latest results, the Juno team has concluded that hydrogen-rich gas is flowing asymmetrically deep in the planet.

These findings were also presented in a study titled Comparing Jupiter interior structure models to Juno gravity measurements and the role of a dilute core, which appeared in the May 28th issue of Geophysical Research Letters. The study was led by Sean Wahl, a grad student from UC Berkeley, and included members from the Weizmann Institute of Science, the Southwest Research Institute (SwRI), NASA’s Goddard Space Flight Center and the Jet Propulsion Laboratory.

Another interesting find was that Jupiter’s gravity field varies with depth, which indicated that material is flowing as far down as 3,000 km (1,864 mi). Combined with information obtained during previous perijoves, this latest data suggests that Jupiter’s core is small and poorly defined. This flies in the face of previous models of Jupiter, which held that the outer layers are gaseous while the interior ones are made up of metallic hydrogen and a rocky core.

As Tristan Guillot – a planetary scientist at the Observatory of the Côte d’Azur in Nice, France, and a co-author on the study – indicated during the meeting, “This is something that was not expected. We were not sure at all whether we would be able to see that… It’s clear that giant planets have a lot of secrets.”

 

This artist's illustration shows Juno's Microwave Radiometer observing deep into Jupiter's atmosphere. The image shows real data from the 6 MWR channels, arranged by wavelength. Credit: NASA/SwRI/JPL
This artist’s illustration shows Juno’s Microwave Radiometer observing deep into Jupiter’s atmosphere. The image shows real data from the 6 MWR channels, arranged by wavelength. Credit: NASA/SwRI/JPL

But of course, more passes and data are needed in order to pinpoint how strong the flow of gases are at various depths, which could resolve the question of how Jupiter’s interior is structured. In the meantime, the Juno scientists are pouring over the probe’s gravity data hoping to see what else it can teach them. For instance, they also want to know how far the Great Red Spot extends into the amotpshere.

This anticyclonic storm, which was first spotted in the 17th century, is Jupiter’s most famous feature. In addition to being large enough to swallow Earth whole – measuring some 16,000 kilometers (10,000 miles) in diameter – wind speeds can reach up to 120 meters per second (432 km/h; 286 mph) at its edges. Already the JunoCam has snapped some very impressive pictures of this storm, and other data has indicated that the storm could run deep.

In fact, on July 10th, 2017, the Juno probe passed withing 9,000 km (5,600 mi) of the Great Red Spot, which took place during its sixth orbit (perijove six) of Jupiter. With it’s suite of eight scientific instruments directed at the storm, the probe obtained readings that indicated that the Great Red Spot could also extend hundreds of kilometers into the interior, or possibly even deeper.

As David Stevenson, a planetary scientist at the California Institute of Technology and a co-author on the study, said during the meeting, “It’s not yet clear that it is so deep it will show up in gravity data. But we’re trying”.

Jupiter’s Great Red Spot, as imaged by the Juno spacecraft’s JunoCam at a distance of just 9,000 km (5,600 mi) from the atmosphere. Credit : NASA/SwRI/MSSS/TSmith

Other big surprises which Juno has revealed since it entered orbit around Jupiter include the clusters of cyclones located at each pole. These were visible to the probe’s instruments in both the visible and infrared wavelengths as it made its first maneuver around the planet, passing from pole to pole. Since Juno is the first space probe in history to orbit the planet this way, these storms were previously unknown to scientists.

In total, Juno spotted eight cyclonic storms around the north pole and five around the south pole. Scientists were especially surprised to see these, since computer modelling suggests that such small storms would not be stable around the poles due to the planet’s swirling polar winds. The answer to this, as indicated during the presentation, may have to do with a concept known as vortex crystals.

As Fachreddin Tabataba-Vakili – a planetary scientist at NASA’s Jet Propulsion Laboratory and a co-author on the study – explained, such crystals are created when small vortices form and persist as the material in which they are embedded continues to flow. This phenomenon has been seen on Earth in the form of rotating superfluids, and Jupiter’s swirling poles may possess similar dynamics.

In the short time that Juno has been operating around Jupiter, it has revealed much about the planet’s atmosphere, interior, magnetic field and internal dynamics. Long after the mission is complete – which will take place in February of 2018 when the probe is crashed into Jupiter’s atmosphere – scientists are likely to be sifting through all the data it obtained, hoping to solve any remaining mysteries from the Solar System’s largest and most massive planet.

Further Reading: Nature

Juno Mission Makes Mysterious Finds about Auroras on Jupiter

Even after decades of study, Jupiter’s atmosphere continues to be something of a mystery to scientists. Consistent with the planet’s size, its atmosphere is the largest in the Solar System, spanning over 5,000 km (3,000 mi) in altitude and boasting extremes in temperature and pressure. On top of that, the planet’s atmosphere experiences the most powerful auroras in the Solar System.

Studying this phenomena has been one of the main goals of the Juno probe, which reached Jupiter on July 5th, 2016. However, after analyzing data collected by the probe’s instruments, scientists at Johns Hopkins University Applied Physics Laboratory (JHUAPL) were surprised to find that Jupiter’s powerful magnetic storms do not have the same source as they do on Earth.

The study which details these findings, “Discrete and Broadband Electron Acceleration in Jupiter’s Powerful Aurora“, recently appeared in the scientific journal Nature. Led by Barry Mauk, a scientist with the JHUAPL, the team analyzed data collected by Juno’s Ultraviolet Spectrograph (UVS) and Jovian Energetic Particle Detector Instrument (JEDI) to study Jupiter’s polar regions.

Ultraviolet auroral images of Jupiter from the Juno Ultraviolet Spectrograph instrument. Credit: NASA/SwRI/Randy Gladstone

As with Earth, on Jupiter, auroras are the result of intense radiation and Jupiter’s magnetic field. When this magnetosphere aligns with charged particles, it has the effect of accelerating electrons towards the atmosphere at high energy levels. In the course of examining Juno’s data, the JHUAPL team observed signatures of electrons being accelerated toward the Jovian atmosphere at energy levels of up to 400,000 electron volts.

This is roughly 10 to 30 times higher than what is experienced here on Earth, where only several thousand volts are typically needed to generate the most intense aurora. Given that Jupiter has the most powerful auroras in the Solar System, the team was not surprised to see such powerful forces at work within the planet’s atmosphere. What was surprising, however, was that this was not the source of the most intense auroras.

As Dr. Mauk, who leads the investigation team for the APL-built JEDI instrument and was the lead author on the study , explained in a JHUAPL press release:

“At Jupiter, the brightest auroras are caused by some kind of turbulent acceleration process that we do not understand very well. There are hints in our latest data indicating that as the power density of the auroral generation becomes stronger and stronger, the process becomes unstable and a new acceleration process takes over. But we’ll have to keep looking at the data.”

Image compiled using data from Juno’s Ultraviolet Spectrograph, which marks the path of Juno’s readings of Jupiter’s auroras. Credit: NASA/SwRI/Randy Gladstone

These findings could have significant implications for the study of Jupiter, who’s composition and atmospheric dynamics continue to be a source of mystery. It also has implications or the study of extra-solar gas giants and planetary systems. In recent decades, the study of these systems has revealed hundreds of gas giants that have ranged in size from being Neptune-like to many times the size of Jupiter (aka. “Super-Jupiters”).

These gas giants have also shown significant variations in orbit, ranging from being very close to their respective suns to very far (i.e. “Hot Jupiters” to “Cold Gas Giants”). By studying Jupiter’s ability to accelerate charged particles, astronomers will be able to make more educated guesses about space weather, radiation environments, and the risks they pose to space missions.

This will come in handy when it comes time to mount future missions to Jupiter, as well as deep-space and maybe even interstellar space. As Mauk explained:

“The highest energies that we are observing within Jupiter’s auroral regions are formidable. These energetic particles that create the auroras are part of the story in understanding Jupiter’s radiation belts, which pose such a challenge to Juno and to upcoming spacecraft missions to Jupiter under development. Engineering around the debilitating effects of radiation has always been a challenge to spacecraft engineers for missions at Earth and elsewhere in the solar system. What we learn here, and from spacecraft like NASA’s Van Allen Probes and MMS that are exploring Earth’s magnetosphere, will teach us a lot about space weather and protecting spacecraft and astronauts in harsh space environments. Comparing the processes at Jupiter and Earth is incredibly valuable in testing our ideas of how planetary physics works.”

Before the Juno mission is scheduled to wrap up (in February of 2018), the probe is likely to reveal a great many things about the planet’s composition, gravity field, magnetic field and polar magnetosphere. In so doing, it will address long-standing mysteries about how the planet formed and evolved, which will also shed light on the history of the Solar System and extra-solar systems.

Further Reading: JHUAPL, Nature

We’re About to Get Our Closest Look at Jupiter’s Great Red Spot

When the Juno mission reached Jupiter on July 5th, 2016, it became the second mission in history to establish orbit around the Solar System’s largest planet. And in the course of it conducting its many orbits, it has revealed some interesting things about Jupiter. This has included information about its atmosphere, meteorological phenomena, gravity, and its powerful magnetic fields.

And just yesterday – on Monday, July 10th at 7:06 p.m. PDT (11:06 p.m. EDT) – just days after the probe celebrated its first year of orbiting the planet, the Juno mission passed directly over Jupiter’s most famous feature – the Great Red Spot. This massive anticyclonic storm has been a focal point for centuries, and Juno’s scheduled flyby was the closest any mission has ever come to it.

Jupiter’s Great Red Spot was first observed during the late 17th century, either by Robert Hooke or Giovanni Cassini. By 1830, astronomers began monitoring this anticyclonic storm, and have noted periodic expansions and regressions in its size ever since. Today, it is 16,000 kilometers (10,000 miles) in diameter and reaches wind speeds of 120 meters per second (432 km/h; 286 mph) at the edges.

The Juno spacecraft isn’t the first one to visit Jupiter. Galileo went there in the mid 90’s, and Voyager 1 snapped a nice picture of the clouds on its mission. Credit: NASA

As part of its sixth orbit of Jupiter’s turbulent cloud tops,  Juno passed close to Jupiter’s center (aka. perijove), which took place at 6:55 p.m. PDT (9:55 p.m. EDT). Eleven minutes later – at 7:06 p.m. PDT (10:06 p.m. EDT) – the probe flew over the Great Red Spot. In the process, Juno was at a distance of just 9,000 km (5,600 miles) from the anticyclonic storm, which is the closest any spacecraft has ever flown to it.

During the flyby, Juno had all eight of its scientific instruments (as well its imager, the JunoCam) trained directly on the storm. With such an array aimed at this feature, NASA expects to learn more about what has been powering this storm for at least the past three and a half centuries. As Scott Bolton, the principal investigator of Juno at the Southwest Research Institute (SwRI), said prior to the event in a NASA press release:

“Jupiter’s mysterious Great Red Spot is probably the best-known feature of Jupiter. This monumental storm has raged on the Solar System’s biggest planet for centuries. Now, Juno and her cloud-penetrating science instruments will dive in to see how deep the roots of this storm go, and help us understand how this giant storm works and what makes it so special.”

This perijove and flyby of the Giant Red Spot also comes just days after Juno celebrated its first anniversary around Jupiter. This took place on July 4th at 7:30 p.m. PDT (10:30 p.m. EDT), at which point, Juno had been in orbit around the Jovian planet for exactly one year. By this time, the spacecraft had covered a distance of 114.5 million km (71 million mi) while orbiting around the planet.

This artist's illustration shows Juno's Microwave Radiometer observing deep into Jupiter's atmosphere. The image shows real data from the 6 MWR channels, arranged by wavelength. Credit: NASA/SwRI/JPL
This artist’s illustration shows Juno’s Microwave Radiometer observing deep into Jupiter’s atmosphere. The image shows real data from the 6 MWR channels, arranged by wavelength. Credit: NASA/SwRI/JPL

The information that Juno has collected in that time with its advanced suite of instruments has already provided fresh insights into Jupiter’s interior and the history of its formation. And this information, it is hoped, will help astronomers to learn more about the Solar System’s own history of formation. And in the course of making its orbits, the probe has been put through its paces, absorbing radiation from Jupiter’s powerful magnetic field.

As Rick Nybakken, the project manager for Juno at NASA’s Jet Propulsion Laboratory, put it:

“The success of science collection at Jupiter is a testament to the dedication, creativity and technical abilities of the NASA-Juno team. Each new orbit brings us closer to the heart of Jupiter’s radiation belt, but so far the spacecraft has weathered the storm of electrons surrounding Jupiter better than we could have ever imagined.”

The Juno mission is set to conclude this coming February, after completing 6 more orbits of Jupiter. At this point, and barring any mission extensions, the probe will be de-orbited to burn up in Jupiter’s outer atmosphere. As with the Galileo spacecraft, this is meant to avoid any possibility of impact and biological contamination with one of Jupiter’s moons.

Further Reading: NASA

Juno is Ready to Tell Us What it Found at Jupiter

The tightly clustered storms that crowd Jupiter's polar regions are another of the gas giant's mysteries. In this image, cyclones the size of Earth bump up against each other at the south pole. Image: NASA/JPL-Caltech/SwRI/MSSS/Betsy Asher Hall/Gervasio Robles

Even a casual observer can see how complex Jupiter might be. Its Great Red Spot is one of the most iconic objects in our Solar System. The Great Red Spot, which is a continuous storm 2 or 3 times as large as Earth, along with Jupiter’s easily-seen storm cloud belts, are visual clues that Jupiter is a complex place.

We’ve been observing the Great Red Spot for almost 200 years, so we’ve known for a long time that something special is happening at Jupiter. Now that the Juno probe is there, we’re finding that Jupiter might be a more surprising place than we thought.

“There is so much going on here that we didn’t expect that we have had to take a step back and begin to rethink of this as a whole new Jupiter.” – Scott Bolton, Juno’s Principal Investigator at the Southwest Research Institute.

So far, the stunning images delivered to us by the JunoCam have stolen the show. But Juno is a science mission, and the fantastic images we’re feasting on might stir the imagination, but it’s the science that’s at the heart of the mission.

Just one of the many beautiful images of Jupiter we're accustomed to seeing. NASA has invited interested citizens to process JunoCam images and has made them available for anyone to use. NASA / SwRI / MSSS / Gerald Eichstädt / Seán Doran © public domain
Just one of the many beautiful images of Jupiter we’re accustomed to seeing. NASA has invited interested citizens to process JunoCam images and has made them available for anyone to use. NASA / SwRI / MSSS / Gerald Eichstädt / Seán Doran © public domain

The Juno probe arrived at Jupiter in July 2016, and completed its first data-pass on August 27th, 2016. That pass took it to within 4,200 km of Jupiter’s cloud tops. Results from that first pass are being published in the journal Science and in Geophysical Research Letters.

Taken together, the results confirm what we might have guessed by just looking at Jupiter from afar: it is a stormy, complex, turbulent world.

“It was a long trip to get to Jupiter, but these first results already demonstrate it was well worth the journey.” – Diane Brown, Juno Program Executive.

“We are excited to share these early discoveries, which help us better understand what makes Jupiter so fascinating,” said Diane Brown, Juno program executive at NASA Headquarters in Washington. “It was a long trip to get to Jupiter, but these first results already demonstrate it was well worth the journey.”

Jupiter’s Magnetic Field

We’ve known for a long time that Jupiter has the most powerful magnetic field in the Solar System. In fact, the magnetic field is what shaped the design of the Juno probe, and the profile of the mission itself. Juno’s Magnetometer Investigation (MAG) has measured the gas giant’s magnetosphere up close, and these measurements tell us that the magnetic field is even stronger than anticipated, and its shape is more irregular as well. At 7.66 Gauss, the field is about 10 times more powerful than Earth.

The irregularities in the magnetic field are an indication that the field is generated closer to the surface than thought. Earth generates its magnetic field from it its rotating core, but because Jupiter’s is “lumpy”, or stronger in some regions than in others, the gas giant’s magnetic field might be generated above its metallic hydrogen layer.

Results from Juno's first data-pass suggest that Jupiter's powerful magnetic field is generated closer to the surface than previously thought. It may be generated above the core of metallic hydrogen. Image: By Kelvinsong - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=31764016
Results from Juno’s first data-pass suggest that Jupiter’s powerful magnetic field is generated closer to the surface than previously thought. It may be generated above the core of metallic hydrogen. Image: By Kelvinsong – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=31764016

“Juno is giving us a view of the magnetic field close to Jupiter that we’ve never had before,” – Jack Connerney, Juno Deputy Principal Investigator

“Juno is giving us a view of the magnetic field close to Jupiter that we’ve never had before,” said Jack Connerney, Juno deputy principal investigator and the lead for the mission’s magnetic field investigation at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Already we see that the magnetic field looks lumpy: it is stronger in some places and weaker in others. This uneven distribution suggests that the field might be generated by dynamo action closer to the surface, above the layer of metallic hydrogen. Every flyby we execute gets us closer to determining where and how Jupiter’s dynamo works.”

Jupiter’s Atmosphere

Juno’s Microwave Radiometer (MWR) is designed to probe Jupiter’s thick atmosphere. It can detect the thermal microwave radiation in the atmosphere, both at the surface, and much deeper. Data from the MWR shows us that the storm belts are mysteries themselves.

This artist's illustration shows Juno's Microwave Radiometer observing deep into Jupiter's atmosphere. The image shows real data from the 6 MWR channels, arranged by wavelength. Credit: NASA/SwRI/JPL
This artist’s illustration shows Juno’s Microwave Radiometer observing deep into Jupiter’s atmosphere. The image shows real data from the 6 MWR channels, arranged by wavelength. Credit: NASA/SwRI/JPL

The belts near Jupiter’s equator extend deep into the atmosphere, while other belts seem to evolve and transform into other structures. The MWR can probe a few hundred kilometers into the atmosphere, where it has found variable and increasing amounts of ammonia to that depth.

Polar Regions and Auroras

Jupiter is home to intense aurora activity at both poles. One of Juno’s mission goals is to study those auroras and the powerful polar magnetic fields that create them. Initial observations from Juno suggest that they are formed differently than Earthly auroras.

Juno is in a unique position to study the magnetosphere and the auroras. Its elongated polar orbit allows it to span the entire magnetosphere all the way from the bow shock to the planet itself.

The tilt of Juno's orbit relative to Jupiter changes over the course of the mission, sending the spacecraft increasingly deeper into the planet's intense radiation belts. This also gives Juno the ability to study the structure of the magnetosphere. Credit: NASA/JPL-Caltech
The tilt of Juno’s orbit relative to Jupiter changes over the course of the mission, sending the spacecraft increasingly deeper into the planet’s intense radiation belts. This also gives Juno the ability to study the structure of the magnetosphere. Credit: NASA/JPL-Caltech

According to the paper detailing the initial data on Jupiter’s magnetosphere an auroras, many of the observations have “terrestrial analogs.” But other aspects are very Jovian, and have no counterpart on Earth.

“…a radically different conceptual model of Jupiter’s interaction with its space environment.” – from J. E. P. Connerney et. al., 2017

As the authors say in their summary, “We observed plasmas upwelling from the ionosphere, providing a mechanism whereby Jupiter helps populate its magnetosphere. The weakness of the magnetic field-aligned electric currents associated with the main aurora and the broadly distributed nature of electron beaming in the polar caps suggest a radically different conceptual model of Jupiter’s interaction with its space environment.”

Polar Storms

JunoCam has also found some puzzling features in Jupiter’s atmosphere. The poles themselves are populated by densely clustered, swirling storms the size of Earth. Since they’ve only been observed briefly, there are a host of unanswered questions about them.

“We’re puzzled as to how they could be formed, how stable the configuration is, and why Jupiter’s north pole doesn’t look like the south pole.” – Scott Bolton, Juno’s Principal Investigator at the Southwest Research Institute

“We’re puzzled as to how they could be formed, how stable the configuration is, and why Jupiter’s north pole doesn’t look like the south pole,” said Bolton. “We’re questioning whether this is a dynamic system, and are we seeing just one stage, and over the next year, we’re going to watch it disappear, or is this a stable configuration and these storms are circulating around one another?”

The tightly clustered storms that crowd Jupiter's polar regions are another of the gas giant's mysteries. In this image, cyclones the size of Earth bump up against each other at the south pole. Image:  NASA/JPL-Caltech/SwRI/MSSS/Betsy Asher Hall/Gervasio Robles
The tightly clustered storms that crowd Jupiter’s polar regions are another of the gas giant’s mysteries. In this image, cyclones the size of Earth bump up against each other at the south pole. Image: NASA/JPL-Caltech/SwRI/MSSS/Betsy Asher Hall/Gervasio Robles

The Great Red Spot: Juno’s Next Target

Juno’s purposeful orbit takes it extremely close to the cloud tops, where it can perform powerful science. But the orbit also takes it a long way from Jupiter. Every 53 days it takes another plunge at Jupiter, where it gathers its next set of observations.

“Every 53 days, we go screaming by Jupiter, get doused by a fire hose of Jovian science, and there is always something new.” – Scott Bolton, Juno’s Principal Investigator at the Southwest Research Institute.

“Every 53 days, we go screaming by Jupiter, get doused by a fire hose of Jovian science, and there is always something new,” said Bolton. “On our next flyby on July 11, we will fly directly over one of the most iconic features in the entire solar system — one that every school kid knows — Jupiter’s Great Red Spot. If anybody is going to get to the bottom of what is going on below those mammoth swirling crimson cloud tops, it’s Juno and her cloud-piercing science instruments.”

The JunoCam's next target: Jupiter's iconic Great Red Spot. Image:  NASA/JPL-Caltech/SwRI/MSSS/Roman Tkachenko
Juno’s next target: Jupiter’s iconic Great Red Spot. Image: NASA/JPL-Caltech/SwRI/MSSS/Roman Tkachenko

During each pass, Juno collects about 6 megabytes of data, which it sends back to Earth via the Deep Space Network. After that, the data is analyzed and published.

Juno has many more fly-bys of Jupiter before it’s sent to its end in the atmosphere of Jupiter. We can expect many more surprises, and hopefully some answers, between now and then.

Does Jupiter Have a Solid Core?

The gas giants have always been a mystery to us. Due to their dense and swirling clouds, it is impossible to get a good look inside them and determine their true structure. Given their distance from Earth, it is time-consuming and expensive to send spacecraft to them, making survey missions few and far between. And due to their intense radiation and strong gravity, any mission that attempts to study them has to do so carefully.

And yet, scientists have been of the opinion for decades that this massive gas giant has a solid core. This is consistent with our current theories of how the Solar System and its planets formed and migrated to their current positions. Whereas the outer layers of Jupiter are composed primarily of hydrogen and helium, increases in pressure and density suggest that closer to the core, things become solid.

Structure and Composition:

Jupiter is composed primarily of gaseous and liquid matter, with denser matter beneath. It’s upper atmosphere is composed of about 88–92% hydrogen and 8–12% helium by percent volume of gas molecules, and approx. 75% hydrogen and 24% helium by mass, with the remaining one percent consisting of other elements.

upiter's structure and composition. (Image Credit: Kelvinsong CC by S.A. 3.0)
Jupiter’s structure and composition. Credit: Kelvinsong CC by S.A. 3.0

The atmosphere contains trace amounts of methane, water vapor, ammonia, and silicon-based compounds, as well as trace amounts of benzene and other hydrocarbons. There are also traces of carbon, ethane, hydrogen sulfide, neon, oxygen, phosphine, and sulfur. Crystals of frozen ammonia have also been observed in the outermost layer of the atmosphere.

The interior contains denser materials, such that the distribution is roughly 71% hydrogen, 24% helium and 5% other elements by mass. It is believed that Jupiter’s core is a dense mix of elements – a surrounding layer of liquid metallic hydrogen with some helium, and an outer layer predominantly of molecular hydrogen. The core has also been described as rocky, but this remains unknown as well.

In 1997, the existence of the core was suggested by gravitational measurements, indicating a mass of 12 to 45 times the mass of Earth, or roughly 4%–14% of the total mass of Jupiter. The presence of a core is also supported by models of planetary formation that indicate how a rocky or icy core would have been necessary at some point in the planet’s history. Otherwise, it would not have been able to collect all of its hydrogen and helium from the protosolar nebula – at least in theory.

However, it is possible that this core has since shrunk due to convection currents of hot, liquid, metallic hydrogen mixing with the molten core. This core may even be absent now, but a detailed analysis is needed before this can be confirmed. The Juno mission, which launched in August 2011 (see below), is expected to provide some insight into these questions, and thereby make progress on the problem of the core.

Formation and Migration:

Our current theories regarding the formation of the Solar System claim that the planets formed about 4.5 billion years ago from a Solar Nebula (i.e. Nebular Hypothesis). Consistent with this theory, Jupiter is believed to have formed as a result of gravity pulling swirling clouds of gas and dust together.

Jupiter acquired most of its mass from material left over from the formation of the Sun, and ended up with more than twice the combined mass of the other planets. In fact, it has been conjectured that it Jupiter had accumulated more mass, it would have become a second star. This is based on the fact that its composition is similar to that of the Sun – being made predominantly of hydrogen.

Artist’s concept of a young star surrounded by a disk of gas and dust – called a protoplanetary disk. Credit: NASA/JPL-Caltech

In addition, current models of Solar System formation also indicate that Jupiter formed farther out from its current position. In what is known as the Grand Tack Hypothesis, Jupiter migrated towards the Sun and settled into its current position by roughly 4 billion years ago. This migration, it has been argued, could have resulted in the destruction of the earlier planets in our Solar System – which may have included Super-Earths closer to the Sun.

Exploration:

While it was not the first robotic spacecraft to visit Jupiter, or the first to study it from orbit (this was done by the Galileo probe between 1995 and 2003), the Juno mission was designed to investigate the deeper mysteries of the Jovian giant. These include Jupiter’s interior, atmosphere, magnetosphere, gravitational field, and the history of the planet’s formation.

The mission launched in August 2011 and achieved orbit around Jupiter on July 4th, 2016. The probe entered its polar elliptical orbit after completing a 35-minute-long firing of the main engine, known as Jupiter Orbital Insertion (or JOI). As the probe approached Jupiter from above its north pole, it was afforded a view of the Jovian system, which it took a final picture of before commencing JOI.

Since that time, the Juno spacecraft has been conducting perijove maneuvers – where it passes between the northern polar region and the southern polar region – with a period of about 53 days. It has completed 5 perijoves since it arrived in June of 2016, and it is scheduled to conduct a total of 12 before February of 2018. At this point, barring any mission extensions, the probe will de-orbit and burn up in Jupiter’s outer atmosphere.

As it makes its remaining passes, Juno will gather more information on Jupiter’s gravity, magnetic fields, atmosphere, and composition. It is hoped that this information will teach us much about how the interaction between Jupiter’s interior, its atmosphere and its magnetosphere drives the planet’s evolution. And of course, it is hoped to provide conclusive data on the interior structure of the planet.

Does Jupiter have a solid core? The short answer is, we don’t know… yet. In truth, it could very well have a solid core composed of iron and quartz, which is surrounded by a thick layer of metallic hydrogen. It is also possible that interaction between this metallic hydrogen and the solid core caused the the planet to lose it some time ago.

The South Pole of Jupiter, taken during the Juno mission’s third orbit (Perijove 3). Credits: NASA/JPL-Caltech/SwRI/MSSS/ Luca Fornaciari © cc nc sa

At this point, all we can do is hope that ongoing surveys and missions will yield more evidence. These are not only likely to help us refine our understanding of Jupiter’s internal structure and its formation, but also refine our understanding of the history of the Solar System and how it came to be.

We have written many articles about Jupiter for Universe Today. Here Ten Interesting Facts About Jupiter, How Big is Jupiter?, How Long Does it Take to get to Jupiter?, What is the Weather Like on Jupiter?, How Far is Jupiter from the Sun?, and The Orbit of Jupiter. How Long is a Year on Jupiter?

If you’d like more information on Jupiter, check out Hubblesite’s News Releases about Jupiter, and here’s a link to NASA’s Solar System Exploration Guide to Jupiter.

We’ve also recorded an episode of Astronomy Cast just about Jupiter. Listen here, Episode 56: Jupiter.

Sources:

Juno Sees Overlapping Colliding Clouds on Jupiter

The Juno mission has made some remarkable finds since it reached Jupiter in July of 2016. During the many orbits it has made around Jupiter’s poles – which occur every 53 days – some stunning imagery has resulted. Not only have these pictures revealed things about Jupiter’s atmosphere, they have also been an opportunity for the public to participate in the exploration of this giant planet.

The latest feature that was publicly selected to be photographed is known as “STB Spectre“. This feature  was photographed on March 27th, 2017, at 2:06 a.m. PDT (5:06 a.m. EDT), when Juno was 12,700 km from the planet. During this pass, the JunoCam captured a series of light and dark clouds coming together in Jupiter’s South Tropical Region (STR).

The left side of the photograph corresponds to the South Temperate Belt (STB), a prominent belt in Jupiter’s Southern Hemisphere which is typically darker. It is here that “the Spectre” – the wide bluish streaks on the upper right side of the photograph – can be seen, and which represent a long-lived storm that was taking place when the area was photographed.

Unprocessed JunoCam image showing the points of interest (POIs) known as “STB Spectre” and “The White Solid”. Credit: NASA/SwRI/MSSS

On the right side of the image, we see the neighboring Southern Tropical Zone (STropZ), one of the most prominent zones on the planet. Here, we see another atmospheric condition colliding with the Spectre, one which is characterized by a series of anticyclonic storms (the small white ovals). Not surprisingly, it is within these two bands that part of the large anticyclonic storms known as the “Great Red Spot” and “Red Spot Junior” also exist.

Like all images snapped by the JunoCam since the probe began orbiting Jupiter, this image was made available to the public. In this case, the image was processed by Roman Tkachenko, an amateur astronomer, image processor, and 3D artist who’s body of work includes images and visualizations for the New Horizons mission. The description was produced by John Rogers, the citizen scientist who identified the point of interest.

As Tkachenko Universe Today via email, working with these missions pictures is all about bringing raw images to life:

“This image is based on a raw image. Working with raw data you can get a higher resolution than we can see in already constructed, and map-projected official versions. I worked with colors, sharpness and dynamic range to show more details and variety.”

This is something new for a space mission, where the public has a direct say in what features will be photographed for study, and can help process them as well.The participation of amateur astronomers and citizen scientists in this mission is an opportunity to be involved in something gorgeous,” said Tkachenko. “They can also show their skills to the public and help the Juno team look at all these data from different angles.

JunoCam closeups of the STB Spectre, with adjacent image showing the SSTB (‘string of pearls’). Credit: NASA/SwRI/MSSS

The STB Spectre was one of five Points of Interest (POIs) that were selected by the public to be photographed during Perijove 5 – Juno’s fifth orbit of the planet, which began on March 27th, 2017. Before the next maneuver (Perijove 6) commences on May 19th, 2017, the public will once again be able to vote on what features they want to see photographed.

Things that have been captured during previous orbits include the stunning image of the “Jovian pearl“, a detailed view of Jupiter’s northern clouds, breathtaking images of the swirling clouds round Jupiter’s northern and southern poles. Many more are sure to follow between now and July 2018, as Juno conducts its seven remaining perijove maneuvers before being de-orbited and burning up in Jupiter’s atmosphere.

To learn more about the rules for voting, and to vote on what you’d like the JunoCam to capture, check out the Southwest Research Institute’s (SwRI) JunoCam voting page. And be sure to enjoy this mission video:

Further Reading: NASA

Juno Will Get No Closer To Jupiter Due To Engine Troubles

On July 4th, 2016, the Juno mission established orbit around Jupiter, becoming the second spacecraft in history to do so (after the Galileo probe). Since then, the probe has been in a regular 53.4-day orbit (known as perijove), moving between the poles to avoid the worst of its radiation belts. Originally, Juno’s mission scientists had been hoping to reduce its orbit to a 14-day cycle so the probe could make more passes to gather more data.

To do this, Juno was scheduled for an engine burn on Oct. 19th, 2016, during its second perijovian maneuver. Unfortunately, a technical error prevented this  from happening. Ever since, the mission team has been pouring over mission data to determine what went wrong and if they could conduct an engine burn at a later date. However, the mission team has now concluded that this won’t be possible.

The technical glitch which prevented the firing took place weeks before the engine burn was scheduled to take place, and was traced to two of the engines helium check valves. After the propulsion system was pressurized, the valves took several minutes to open – whereas they took only seconds during previous engine burns. Because of this, the mission leaders chose to postpone the firing until they could get a better understanding of why the glitch happened.

This amateur-processed image was taken on Dec. 11th, 2016, at 9:27 a.m. PST (12:27 p.m. EST), as NASA’s Juno spacecraft performed its third close flyby of Jupiter. Credits: NASA/JPL-Caltech/SwRI/MSSS/Eric Jorgensen

And after pouring over mission data from the past few months and performing calculations on possible maneuvers, Juno’s science team came to the conclusion that an engine burn might be counter-productive at this point. As Rick Nybakken, the Juno project manager at NASA’s Jet Propulsion Laboratory (JPL), explained in a recent NASA press release:

“During a thorough review, we looked at multiple scenarios that would place Juno in a shorter-period orbit, but there was concern that another main engine burn could result in a less-than-desirable orbit. The bottom line is a burn represented a risk to completion of Juno’s science objectives.”

However, this is not exactly bad news for the mission. It’s current perijove orbit takes it from one pole to the other, allowing it to pass over the cloud tops at a distance of around 4,100 km (2,600 mi) at its closest. At its farthest, the spacecraft reaches a distance of 8.1 million km (5.0 million mi) from the gas giant, which places it far beyond the orbit of Callisto.

During each pass, the probe is able to peak beneath the thick clouds to learn more about the planet’s atmosphere, internal structure, magnetosphere, and formation. And while a 14-day orbital period would allow for it to conduct 37 orbits before its mission is scheduled to wrap up, its current 53.4-day period will allow for more information to be collected on each pass.

And as Thomas Zurbuchen, the associate administrator for NASA’s Science Mission Directorate in Washington, declared:

“Juno is healthy, its science instruments are fully operational, and the data and images we’ve received are nothing short of amazing. The decision to forego the burn is the right thing to do – preserving a valuable asset so that Juno can continue its exciting journey of discovery.”

In the meantime, the Juno science team is still analyzing the returns from Juno’s four previous flybys – which took place on August 27th, October 19th, December 11th, and February 2nd, 2017, respectively. With each pass, more information is revealed about the planet’s magnetic fields, aurorae, and banded appearance. The next perijovian maneuver will take place on March 27th, 2017, and will result in more images and data being collected.

Before the mission concludes, the Juno spacecraft will also explore Jupiter’s far magnetotail, its southern magnetosphere, and its magnetopause. The mission is also conducting an outreach program with its JunoCam, which is being guided with assistance of the public. Not only can people vote on which features they want imaged with every flyby, but these images are accessible to “citizen scientists” and amateur astronomers.

Under its current budget plan, Juno will continue to operate through to July 2018, conducting a total of 12 science orbits. At this point, barring a mission extension, the probe will be de-orbited and burn up in Jupiter’s outer atmosphere. As with the Galileo spacecraft, this will be as to avoid any possibility of impact and biological contamination with one of Jupiter’s moons.

Further Reading: NASA

91 Astronomers Combine 1000 Images Into One Amazing Journey to Jupiter

A renewed era of space exploration is underway. Compared to the Space Race of the 20th century, which was characterized by two superpowers locked in a game of “getting there first”, the new era is defined predominantly by cooperation and open participation. One way in which this is evident is the role played by “citizen scientists” and amateur astronomers in exploration missions.

Consider the recently-released short film titled “A Journey to Jupiter” by Peter Rosen – a photographer and digital artist in Stockholm, Sweden. Using over 1000 images taken by amateur planetary photographers from around the world, this film takes viewers on a virtual journey to the Jovian planet, showcasing its weather patterns and dynamic nature in a way that is truly inspiring.

The images that went into making this video were collected by over 91 amateur astronomers over the course of three and a half months (between December 19th, 2014 and March 31st, 2015). After Rosen collected them, he and his associates (Christoffer Svenske and Johan Warell) then spent a year remapping them into cylindrical projections. Rosen then added color corrections, and stitched all the images into a total of 107 maps.

Much like fast-motion videos that illustrate weather patterns on Earth, or the passage of the stars across the night sky, the end result of was a film that shows the motions of Jupiter’s cloud belts and its Great Red Spot in high-resolution. Some 250 revolutions of the planet are illustrated, including from the equatorial band, the south pole, and the north pole.

As Rosen told Universe Today via email, this project was the latest in a lifelong pursuit of making astronomy accessible to the public:

“I have been into Astronomy since I was a teenager in the early 1970’s and immediately I got a passion for astrophotography, and more specifically, photographing the planets. I see astronomy as a life-long passion, so it is quite normal to strive for an evolution in what you do. I had an idea growing slowly for some years that it should be possible to animate the cloud belts of Jupiter and reveal the intricate dynamics of its flows, not just taking still pictures that might point to the changes in the structures but without the obvious visual dynamics of an animation.”

A Journey to Jupiter” was also Rosen’s contribution to the Mission Juno Pro-Amateur Collaboration Project, of which he is part. Established by Glenn Orton of NASA’s Jet Propulsion Laboratory, this effort is one of several that seeks to connect amateurs and professionals in support of space exploration. Back in May of 2016, this group met in Nice, France, for a workshop dedicated to projects and techniques related to Jupiter observations.

Still-pic from Rosen’s “A Journey to Jupiter” video. Credit: Peter Rosen et al via Youtube.

Among other items discussed was the limitations that missions like Juno have to deal with. While it is capable of taking very-high resolution images of Jupiter, these images are highly specific in nature. And before a team of mission scientists are able to color-correct them and stitch them together to create panoramas, etc., they are not always what you might call “visually stunning”.

However, Earth-based observatories are not hampered by this restriction, and can take multiple images of a planet over time that capture it as a whole. And thanks to the availability of sophisticated telescopes and imaging software, amateur astronomers are capable of making important contributions in this regard. And far from these being strictly for scientific purposes, there is also the added benefit of public engagement.

“This has been a very technical and scientifically correct project,” said Rosen, “but as a photographer and digital artist I also wanted to create a work of art that would inspire and appeal to people who are fascinated by the universe but who are not necessarily into astronomy.”

Of course, this does not detract from the scientific value that this film has. For example, it showcases the turbulent nature of Jupiter’s atmosphere in a way that is scientifically accurate. Hence why Ricardo Hueso Alonso – a physicist at the University of Basque Country and a member of the Planetary Virtual Observatory and Laboratory (PVOL) – plans to use the maps to measure Jupiter’s wind speeds at different latitudes.

Reprocessed image taken by the JunoCam during its 3rd close flyby of the planet on Dec. 11. The photo highlights two large ‘pearls’ or storms in Jupiter’s atmosphere. Credit: NASA/JPL-Caltech/SwRI/MSSS

On top of its artistic and scientific merit, “A Journey to Jupiter” also serves as a testament to the skill and capability of the today’s amateur astronomers and planetary photographers. And of course, it draws attention to the efforts of space missions such as Juno, which is currently skimming the clouds of Jupiter to obtain the most comprehensive information about the planet’s atmosphere and magnetic field to date.

Not surprisingly, this is not the first film by Rosen that combines scientific accuracy and fast-motion visuals. The short film Voyager 3, released back in June of 2014, was an homage by Rosen and six other Swedish amateur astronomers to the Voyager 1 mission. As the probe made its 28-day final approach to Jupiter in 1979, it snapped what were the most detailed images of Jupiter at the time.

These images helped to improve our understanding of the gas giant, its atmosphere, and its moons. Among other things, hey revealed the turbulent nature of Jupiter’s atmosphere, and that the Great Red Spot had changed color since the Pioneer 10 and 11 missions had flown by in 1973 and 74. Produced 35 years later, Voyager 3 was an attempt to recreate this historic event using images taken by Swedish amateur astronomers using their own ground-based telescopes.

Over the course of 90 days, Rosen and his colleagues captured one million frames of Jupiter, which resulted in 560 still images of the planet. These were then stitched together using a series of software programs (Winjupos, Photoshop CS6, Fantamorph, and StarryNightPro+) to create a simulation that gives the impression of a probe approaching the planet – i.e. like a third Voyager mission, hence the name of the film.

“As Jupiter was ideally positioned high in the sky in 2013-2014 for us living far up in the northern hemisphere, I decided that it was the right moment to give it a try, so I contacted 6 other amateurs on our local forum that shared my passion for the planets,” Rosen said. “We photographed Jupiter as often as we could during a 3-month period and I took care of the processing of the images which took me a total of 6 months.”

It is an exciting time to be alive. Not only are a greater number of national space agencies taking part in the exploration of the Solar System; but more than ever, citizen scientists, amateurs and members of the general public are able to participate in a way that was never before possible.

To view more work by Peter Rosen, be sure to check out his page at Vimeo.

Further Reading: NASA