From The MPG Institute for Solar System Research [MPG Institut für Sonnensystemforschung](DE): “Oxygen ions in Jupiter’s innermost radiation belts”

From The MPG Institute for Solar System Research [MPG Institut für Sonnensystemforschung](DE)

January 12, 2022
Dr. Birgit Krummheuer
Media and Public Relations
+49 173 3958625
Krummheuer@mps.mpg.de.
Max Planck Institute for Solar System Research, Göttingen

Dr. Elias Roussos
+49 551 394979-457
Roussos@mps.mpg.de
Max Planck Institute for Solar System Research, Göttingen

Dr. Norbert Krupp
+49 551 384979-154
Krupp@mps.mpg.de..
Max Planck Institute for Solar System Research, Göttingen

Researchers find high-energy oxygen and sulfur ions in Jupiter’s inner radiation belts-and a previously unknown ion source.

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From 1995 to 2003, NASA’s Galileo spacecraft explored the Jupiter system. Its final orbits took the probe deep into the giant planet’s innermost radiation belts, where it also performed a close flyby of Amalthea. Credit: Michael Carroll.

National Aeronautics and Space Administration(US) Galileo Spacecraft 1989-2003.

Nearly 20 years after the end of NASA’s Galileo mission to Jupiter, scientists led by the MPG Institute for Solar System Research (MPS) in Germany have unlocked a new secret from the mission’s extensive data sets. For the first time, the research team was able to determine beyond doubt that the high-energy ions surrounding the gas giant as part of its inner radiation belt are primarily oxygen and sulfur ions. They are thought to have originated in volcanic eruptions on Jupiter’s moon Io. Near the orbit of the moon Amalthea, which orbits Jupiter further inward, the team discovered an unexpectedly high concentration of high-energy oxygen ions that cannot be explained by Io’s volcanic activity. A previously unknown ion source must be at work here. The results of the study were published today in the journal Science Advances.

Planets like Earth, Jupiter, and Saturn with global magnetic fields of their own are surrounded by so-called radiation belts: Trapped in the magnetic field, fast moving charged particles such as electrons, protons, and heavier ions whiz around thus forming the invisible, torus-shaped radiation belts.

Van Allen Radiation belts

With their high velocities reaching almost the speed of light, the particles can ionize other molecules when they collide, creating a hazardous environment that can also be dangerous to space probes and their instruments. In this respect, the gas giant Jupiter sports the most extreme radiation belts in the Solar System. In their new publication, researchers from the MPS, The California Institute of Technology (US), The Johns Hopkins Applied Physics Laboratory (US), The Laboratory of Instrumentation and Experimental Particle Physics [Laboratório de Instrumentação e Física Experimental de Partículas](PT), and The Academy of Athens [Ακαδημία Αθηνών](GR) now present the most comprehensive study to date of the heavy ions in Jupiter’s inner radiation belts.

Like Jupiter’s massive magnetic field, its radiation belts extend several million kilometers into space; however, the region within the moon’s orbit of Europa, an area with a radius of about 670,000 kilometers around the gas giant, is the scene of the highest energetic particle densities and velocities. Viewed from Jupiter, Europa is the second of the four large Jovian satellites named “Galilean moons” after their 17th century discoverer. Io is the innermost Galilean moon. With the space probes Pioneer 11 in the mid-1970s, Galileo from 1995 to 2003 [above], and currently Juno, three space missions have so far ventured into this innermost part of these radiation belts and performed in-situ measurements.

NASA Pioneer 11.

National Aeronautics Space Agency(USA) Juno at Jupiter.

“Unfortunately, the data from Pioneer 11 and Juno do not allow us to conclude beyond doubt what kind of ions the spacecraft encountered there,” says MPS scientist Dr. Elias Roussos, lead author of the new study, describing the current state of research. “Therefore, their energies and origin were also unclear until now,” he adds. Only the now rediscovered data from the last months of the Galileo mission is detailed enough to improve this situation.

Venturing into the inner radiation belts

NASA’s Galileo spacecraft reached the Jupiter system in 1995. Equipped with the Heavy Ion Counter (HIC), contributed by the California Institute of Technology, and the Energetic Particle Detector (EPD), developed and built by Johns Hopkins Applied Physics Laboratory in collaboration with the MPS, the mission spent the following eight years providing fundamental insights into the distribution and dynamics of charged particles around the gas giant. However, to protect the spacecraft, it initially flew solely through the outer, less extreme regions of the radiation belts. Only in 2003, shortly before the end of the mission, when a greater risk was justifiable, Galileo ventured into the innermost region within the orbits of the moons Amalthea and Thebe. Viewed from Jupiter, Amalthea and Thebe are the third and fourth moons of the giant planet. The orbits of Io and Europa lie farther outward.

“Because of the exposure to strong radiation, it was to be expected that the measurement data from HIC and EPD from the inner region of the radiation belt would be heavily corrupted. After all, neither of these two instruments was specifically designed to operate in such a harsh environment”, Roussos describes his expectations when he started working on the current study three years ago. Nevertheless, the researcher wanted to see for himself. As a member of NASA’s Cassini mission, he had witnessed Cassini’s final, similarly daring orbits at Saturn two years earlier and analyzed the unique data from that final mission phase. “The thought of the long-completed Galileo mission kept coming to my mind,” Roussos recalls. To his own surprise, among many unusable data sets there were also some that could be processed and analyzed with much effort.

Enigmatic oxygen ions

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While the high-energy oxygen and sulfur ions outside Amalthea’s orbit are supplied from the distant magnetosphere as byproducts of Io’s volcanic eruptions, another source must be responsible for the high concentration of high-energy oxygen ions inward of Amalthea, which prevents the transmission of such ions across its orbit. Credit: MPS.

With the help of this scientific treasure, the authors of the current study have now been able to determine for the first time the ion composition within the inner radiation belts, as well as the ions’ velocities and spatial distribution. In contrast to the radiation belts of Earth and Saturn, which are dominated by protons, the region within the orbit of Io also contains large amounts of the much heavier oxygen and sulfur ions, with oxygen ions prevailing among the two. “The energy distribution of the heavy ions outside the orbit of Amalthea suggests that they are largely introduced from a more distant region of the radiations belts,” Roussos says. The moon Io with its more than 400 active volcanoes, which repeatedly hurl large amounts of sulfur and sulfur dioxide into space, and to a lesser extent, Europa, are likely the main sources.

Further inward, within Amalthea’s orbit, the ion composition changes drastically in favor of oxygen. “The concentration and the energy of oxygen ions there is much higher than expected,” Roussos says. Actually, the concentration should be decreasing in this region, as the moons Amalthea and Thebe absorb incoming ions; the two small moons’ orbits thus form a kind of natural ion barrier. This behavior is, for example, known from radiation belts of the Saturnian system with its many moons.

The only explanation for the increased concentration of oxygen ions is therefore another, local source in the innermost region of the radiation belts. The release of oxygen following the collisions of sulfur ions with the fine dust particles of Jupiter’s rings constitute one possibility, as the researchers’ computer simulations show. The rings, which are much fainter than the Saturnian ones, extend approximately as far as the orbit of Thebe. However, it is also conceivable that low-frequency electromagnetic waves in the magnetospheric environment of the innermost radiation belts heat oxygen ions to the observed energies.

“Currently, it is not possible to distinguish in favor of either of these possible sources,” Roussos says. Any of these two candidate mechanisms, nevertheless, have parallels to high energy particle production in stellar or extrasolar environments, further establishing that Jupiter’s radiation belts extend into the astrophysical realm, a fact that the researcher hopes would justify their future exploration with a dedicated space mission.

See the full article here .

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The MPG Institute for Solar System Research [MPG Institut für Sonnensystemforschung] (DE) has had an eventful history – with several moves, changes of name, and structural developments. The first prototype of the current institute was founded in 1934 in Mecklenburg; it moved to Katlenburg-Lindau in 1946. Not just the location of the buildings changed – the topic of research also moved, from Earth to outer space. In the first decades the focus of research was the stratosphere and ionosphere of the Earth, but since 1997 the institute exclusively researches the physics of planets and the Sun. In January 2014 the Max Planck Institute for Solar System Research has relocated to it’s new home: a new building in Göttingen close to the Northern Campus of the University of Göttingen [Georg-August-Universität Göttingen] (DE).

MPG Institute for the Advancement of Science [MPG zur Förderung der Wissenschaften e. V](DE) is Germany’s most successful research organization. Since its establishment in 1948, no fewer than 18 Nobel laureates have emerged from the ranks of its scientists, putting it on a par with the best and most prestigious research institutions worldwide. The more than 15,000 publications each year in internationally renowned scientific journals are proof of the outstanding research work conducted at MPG Institutes – and many of those articles are among the most-cited publications in the relevant field.

What is the basis of this success? The scientific attractiveness of the MPG Society is based on its understanding of research: MPG institutes are built up solely around the world’s leading researchers. They themselves define their research subjects and are given the best working conditions, as well as free reign in selecting their staff. This is the core of the Harnack principle, which dates back to Adolph von Harnack, the first president of the Kaiser Wilhelm Society, which was established in 1911. This principle has been successfully applied for nearly one hundred years. The MPG Society continues the tradition of its predecessor institution with this structural principle of the person-centered research organization.

The currently 83 MPG Institutes and facilities conduct basic research in the service of the general public in the natural sciences, life sciences, social sciences, and the humanities. MPG Institutes focus on research fields that are particularly innovative, or that are especially demanding in terms of funding or time requirements. And their research spectrum is continually evolving: new institutes are established to find answers to seminal, forward-looking scientific questions, while others are closed when, for example, their research field has been widely established at universities. This continuous renewal preserves the scope the Max Planck Society needs to react quickly to pioneering scientific developments.

MPG Society for the Advancement of Science [MPG Gesellschaft zur Förderung der Wissenschaften e. V.] is a formally independent non-governmental and non-profit association of German research institutes founded in 1911 as the Kaiser Wilhelm Society and renamed the MPG Society in 1948 in honor of its former president, theoretical physicist Max Planck. The society is funded by the federal and state governments of Germany as well as other sources.

According to its primary goal, the MPG Society supports fundamental research in the natural, life and social sciences, the arts and humanities in its 83 (as of January 2014) MPG institutes. The society has a total staff of approximately 17,000 permanent employees, including 5,470 scientists, plus around 4,600 non-tenured scientists and guests. Society budget for 2015 was about €1.7 billion.

The MPG Institutes focus on excellence in research. The MPG Society has a world-leading reputation as a science and technology research organization, with 33 Nobel Prizes awarded to their scientists, and is generally regarded as the foremost basic research organization in Europe and the world. In 2013, the Nature Publishing Index placed the MPG institutes fifth worldwide in terms of research published in Nature journals (after Harvard University (US), Massachusetts Institute of Technology (US), Stanford University (US) and the National Institutes of Health (US)). In terms of total research volume (unweighted by citations or impact), the MPG Society is only outranked by the Chinese Academy of Sciences [中国科学院] (CN), the Russian Academy of Sciences [Росси́йская акаде́мия нау́к](RU) and Harvard University. The Thomson Reuters-Science Watch website placed the Max Planck Society as the second leading research organization worldwide following Harvard University, in terms of the impact of the produced research over science fields.

[The blog owner wishes to editorialize: I do not think all of this boasting is warranted when the combined forces of the MPG Society are being weighed against individual universities and institutions. It is not the combined forces of the cited schools and institutions, that could make some sense. No, it is each separate institution standing on its own.]

The MPG Society and its predecessor Kaiser Wilhelm Society hosted several renowned scientists in their fields, including Otto Hahn, Werner Heisenberg, and Albert Einstein.

History

The organization was established in 1911 as the Kaiser Wilhelm Society, or Kaiser-Wilhelm-Gesellschaft (KWG), a non-governmental research organization named for the then German emperor. The KWG was one of the world’s leading research organizations; its board of directors included scientists like Walther Bothe, Peter Debye, Albert Einstein, and Fritz Haber. In 1946, Otto Hahn assumed the position of President of KWG, and in 1948, the society was renamed the MPG Society after its former President (1930–37) Max Planck, who died in 1947.

The MPG Society has a world-leading reputation as a science and technology research organization. In 2006, the Times Higher Education Supplement rankings of non-university research institutions (based on international peer review by academics) placed the MPG Society as No.1 in the world for science research, and No.3 in technology research (behind AT&T Corporation and the DOE’s Argonne National Laboratory (US).

The domain mpg.de attracted at least 1.7 million visitors annually by 2008 according to a Compete.com study.

MPG Institutes and research groups

The MPG Society consists of over 80 research institutes. In addition, the society funds a number of MPG Research Groups (MPRG) and International MPG Research Schools (IMPRS). The purpose of establishing independent research groups at various universities is to strengthen the required networking between universities and institutes of the MPG Society.

The research units are primarily located across Europe with a few in South Korea and the U.S. In 2007, the Society established its first non-European centre, with an institute on the Jupiter campus of Florida Atlantic University (US) focusing on neuroscience.

The MPG Institutes operate independently from, though in close cooperation with, the universities, and focus on innovative research which does not fit into the university structure due to their interdisciplinary or transdisciplinary nature or which require resources that cannot be met by the state universities.

Internally, MPG Institutes are organized into research departments headed by directors such that each MPG institute has several directors, a position roughly comparable to anything from full professor to department head at a university. Other core members include Junior and Senior Research Fellows.

In addition, there are several associated institutes:

International Max Planck Research Schools
Together with the Association of Universities and other Education Institutions in Germany, the MPG Society established numerous International Max Planck Research Schools (IMPRS) to promote junior scientists:

Cologne Graduate School of Ageing Research, Cologne
International Max Planck Research School for Intelligent Systems, at the MPG Institute for Intelligent Systems (DE) located in Tübingen and Stuttgart
International Max Planck Research School on Adapting Behavior in a Fundamentally Uncertain World (Uncertainty School), at the Max Planck Institutes for Economics, for Human Development, and/or Research on Collective Goods
International Max Planck Research School for Analysis, Design and Optimization in Chemical and Biochemical Process Engineering, Magdeburg
International Max Planck Research School for Astronomy and Cosmic Physics, Heidelberg at the MPG for Astronomy
International Max Planck Research School for Astrophysics, Garching at the MPG Institute for Astrophysics
International Max Planck Research School for Complex Surfaces in Material Sciences, Berlin
International Max Planck Research School for Computer Science, Saarbrücken
International Max Planck Research School for Earth System Modeling, Hamburg
International Max Planck Research School for Elementary Particle Physics, Munich, at the MPG Institute for Physics
International Max Planck Research School for Environmental, Cellular and Molecular Microbiology, Marburg at the MPG Institute for Terrestrial Microbiology
International Max Planck Research School for Evolutionary Biology, Plön at the Max Planck Institute for Evolutionary Biology
International Max Planck Research School “From Molecules to Organisms”, Tübingen at the MPG Institute for Developmental Biology
International Max Planck Research School for Global Biogeochemical Cycles, Jena at the Max Planck Institute for Biogeochemistry
International Max Planck Research School on Gravitational Wave Astronomy, Hannover and Potsdam MPG Institute for Gravitational Physics
International Max Planck Research School for Heart and Lung Research, Bad Nauheim at the MPG Institute for Heart and Lung Research
International Max Planck Research School for Infectious Diseases and Immunity, Berlin at the Max Planck Institute for Infection Biology
International Max Planck Research School for Language Sciences, Nijmegen
International Max Planck Research School for Neurosciences, Göttingen
International Max Planck Research School for Cognitive and Systems Neuroscience, Tübingen
International Max Planck Research School for Marine Microbiology (MarMic), joint program of the MPG Institute for Marine Microbiology in Bremen, the University of Bremen [Universität Bremen](DE), the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, and the Jacobs University Bremen [Jacobs Universität Bremen] (DE)
International Max Planck Research School for Maritime Affairs, Hamburg
International Max Planck Research School for Molecular and Cellular Biology, Freiburg
International Max Planck Research School for Molecular and Cellular Life Sciences, Munich
International Max Planck Research School for Molecular Biology, Göttingen
International Max Planck Research School for Molecular Cell Biology and Bioengineering, Dresden
International Max Planck Research School Molecular Biomedicine, program combined with the ‘Graduate Programm Cell Dynamics And Disease’ at the University of Münster [Westfälische Wilhelms-Universität Münster] (DE) and the MPG Institute for Molecular Biomedicine (DE)
International Max Planck Research School on Multiscale Bio-Systems, Potsdam
International Max Planck Research School for Organismal Biology, at the University of Konstanz [Universität Konstanz] (DE) and the MPG Institute for Ornithology (DE)
International Max Planck Research School on Reactive Structure Analysis for Chemical Reactions (IMPRS RECHARGE), Mülheim an der Ruhr, at the Max Planck Institute for Chemical Energy Conversion (DE)
International Max Planck Research School for Science and Technology of Nano-Systems, Halle at MPG Institute of Microstructure Physics (DE)
International Max Planck Research School for Solar System Science at the University of Göttingen – Georg-August-Universität Göttingen (DE) hosted by MPG Institute for Solar System Research [Max-Planck-Institut für Sonnensystemforschung] (DE)
International Max Planck Research School for Astronomy and Astrophysics, Bonn, at the MPG Institute for Radio Astronomy [MPG Institut für Radioastronomie](DE) (formerly the International Max Planck Research School for Radio and Infrared Astronomy)
International Max Planck Research School for the Social and Political Constitution of the Economy, Cologne
International Max Planck Research School for Surface and Interface Engineering in Advanced Materials, Düsseldorf at MPG Institute for Iron Research [MPG Institut für Eisenforschung] (DE)
International Max Planck Research School for Ultrafast Imaging and Structural Dynamics, Hamburg

Research School Molecular Biomedicine, program combined with the ‘Graduate Programm Cell Dynamics And Disease’ at the University of Münster (DE) and the MPG Institute for Molecular Biomedicine (DE)
International Max Planck Research School on Multiscale Bio-Systems, Potsdam
International Max Planck Research School for Organismal Biology, at the University of Konstanz (DE) and the MPG Institute for Ornithology (DE)
International Max Planck Research School on Reactive Structure Analysis for Chemical Reactions (IMPRS RECHARGE), Mülheim an der Ruhr, at the Max Planck Institute for Chemical Energy Conversion (DE)
International Max Planck Research School for Science and Technology of Nano-Systems, Halle at MPG Institute of Microstructure Physics (DE)
International Max Planck Research School for Solar System Science[49] at theUniversity of Göttingen – Georg-August-Universität Göttingen (DE) hosted by MPG Institute for Solar System Research [Max-Planck-Institut für Sonnensystemforschung] (DE)
International Max Planck Research School for Astronomy and Astrophysics, Bonn, at the MPG Institute for Radio Astronomy [MPG Institut für Radioastronomie](DE) (formerly the International Max Planck Research School for Radio and Infrared Astronomy)
International Max Planck Research School for the Social and Political Constitution of the Economy, Cologne
International Max Planck Research School for Surface and Interface Engineering in Advanced Materials, Düsseldorf at MPG Institute for Iron Research [MPG Institut für Eisenforschung] (DE)
International Max Planck Research School for Ultrafast Imaging and Structural Dynamics, Hamburg