The radiation belts of Jupiter and Saturn

The era of outer planet orbiters (Galileo, Juno and Cassini) is advancing our understanding of how the radiation belts of Jupiter and Saturn are structured, form and evolve well beyond what had been possible during the age of flyby missions and ground-based observations. The nearly two decades-long datasets of these missions, in the context of detailed and long-term observations of Earth's radiation belts, highlight which of the processes that accelerate particles to relativistic kinetic energies and limit their flux intensity can be considered more universal, and thus key for most extraterrestrial magnetospheres, and which reflect the unique aspects of each planet and its magnetospheric system. In this chapter we focus on the in-situ radiation belt observations in the context of theory, simulations and relevant measurements by Earth-based observatories. We describe both the average state and the time variations of Jupiter's and Saturn's radiation belts and associate them with specific physical processes.Comment: 24 pages, 4 figure

Mars and the moons of Saturn

thesi

Wechselwirkungen schwach bzw. nicht-magnetisierter Körper mit Plasmen des Sonnensystems am Beispiel des Mars und der Saturn-Monde

The interaction of weakly or non-magnetized planets and moons with the solar wind as well as with a magnetospheric plasma have been studied at Mars and the moons of Saturn using plasma data from the ASPERA-3 instrument onboard Mars Express and energetic charged particle measurements at the moons of Saturn from the MIMI/LEMMS instrument aboard Cassini, respectively. Data analysis was complemented by hybrid plasma simulations. A series of results have been obtained from the study of each individual system: (a) Plasma moments have been extracted for the martian space environment and moment maps that describe the planet's interaction with the solar wind have been constructed. Asymmetries in the global magnetospheric configuration resulting from the planet's crustal magnetic anomalies have also been investigated. (b) The evolution of energetic particle depletions caused by Saturn's icy moons have been analysed with respect to Saturn's radiation belt dynamics. Similar depletions have also been considered for the detection and the physical characterization of rings and dust structures at Saturn. (c) The physics of plasma absorbing interactions at Saturn have been studied with a three dimensional hybrid plasma simulation code, and the "plasma expansion into the vacuum" problem has been analysed in the subsonic regime.Die Wechselwirkung von schwach oder nicht magnetisierten Planeten und Monden mit dem Sonnenwind sowie mit magnetosphärischen Plasmen wurde beim Mars und bei den Monden des Saturn untersucht. Für den Mars basiert die Analyse auf Daten des ASPERA-3 Instruments auf Mars-Express, während bei den Eismonden des Saturn Daten von MIMI/LEMMS, einem Instrument auf Cassini, verwendet wurden. Die Analyse der Messdaten wurde durch numerische Plasma-Simulationen mithilfe eines Hybrid-Codes unterstützt. Die Untersuchungen dieser Systeme hat zu einer Reihe interessanter Ergebnisse geführt: (a) Es konnten Plasma-Momente gewonnen werden, mit deren Hilfe die Wechselwirkung zwischen der Mars-Ionosphäre und dem Sonnenwind charakterisiert werden kann. Die asymmetrische Struktur der Wechselwirkungsregion resultiert zum Teil aus Krustenfeldern. (b) Die Absorption hochenergetischer magnetosphärischer Teilchen durch Saturns Eismonde wurde untersucht. Einbezogen wurde die Dynamik der Teilchen in den Strahlungsgürteln. Eine Ähnliche Methode wurde verwendet, um Ringe und Staubstrukturen in der Saturn-Magnetosphäre zu studieren. (c) Die Wechselwirkung eines inerten Mondes mit dem magnetosphärischen Plasma wurde mittels dreidimensionaler Hybrid-Simulationen untersucht. Die Plasmadynamik auf der Schweifseite wurde mit einem einfachen Modell für Plasmaexpansion in einem Vakuum verglichen

Proceedings of IMECE

ABSTRACT Reduction of exhaust emissions is a major research task in diesel engine development in view o

Energetic Ion Moments and Polytropic Index in Saturn’s Magnetosphere using Cassini/MIMI Measurements: A Simple Model Based on κ‐Distribution Functions

Moments of the charged particle distribution function provide a compact way of studying the transport, acceleration, and interactions of plasma and energetic particles in the magnetosphere. We employ κ‐distributions to describe the energy spectra of H+ and O+, based on >20 keV measurements by the three detectors of Cassini’s Magnetospheric Imaging Instrument, covering the time period from DOY 183/2004 to 016/2016, 5 < L < 20. From the analytical spectra we calculate the equatorial distributions of energetic ion moments inside Saturn’s magnetosphere and then focus on the distributions of the characteristic energy (Ec=IE/In), temperature, and κ‐index of these ions. A semiempirical model is utilized to simulate the equatorial ion moments in both local time and L‐shell, allowing the derivation of the polytropic index (Γ) for both H+ and O+. Primary results are as follows: (a) The ∼9 < L < 20 region corresponds to a local equatorial acceleration region, where subadiabatic transport of H+ (Γ∼1.25) and quasi‐isothermal behavior of O+ (Γ∼0.95) dominate the ion energetics; (b) energetic ions are heavily depleted in the inner magnetospheric regions, and their behavior appears to be quasi‐isothermal (Γ<1); (c) the (quasi‐) periodic energetic ion injections in the outer parts of Saturn’s magnetosphere (especially beyond 17–18 RS) produce durable signatures in the energetic ion moments; (d) the plasma sheet does not seem to have a ground thermodynamic state, but the extended neutral gas distribution at Saturn provides an effective cooling mechanism that does not allow the plasma sheet to behave adiabatically.Key PointsDerivation of energetic ion moments, κ‐index, characteristic energy, temperature, and polytropic index in Saturn’s magnetospherePresentation of a semiempirical analytical model for the 20 keV energetic ion Pressure, density, and temperatureThe neutral gas at Saturn provides an effective cooling mechanism and does not allow the plasma sheet to behave adiabaticallyPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146558/1/jgra54546.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146558/2/jgra54546_am.pd

Enceladus and Titan: Emerging Worlds of the Solar System (ESA Voyage 2050 White Paper)

Some of the major discoveries of the recent Cassini-Huygens mission have put Titan and Enceladus firmly on the Solar System map. The mission has revolutionised our view of Solar System satellites, arguably matching their scientific importance with that of their planet. While Cassini-Huygens has made big surprises in revealing Titan's organically rich environment and Enceladus' cryovolcanism, the mission's success naturally leads us to further probe these findings. We advocate the acknowledgement of Titan and Enceladus science as highly relevant to ESA's long-term roadmap, as logical follow-on to Cassini-Huygens. In this white paper, we will outline important science questions regarding these satellites and identify the pertinent science themes we recommend ESA cover during the Voyage 2050 planning cycle. Addressing these science themes would make major advancements to the present knowledge we have about the Solar System, its formation, evolution and likelihood that other habitable environments exist outside the Earth's biosphere

The case for studying other planetary magnetospheres and atmospheres in Heliophysics

Heliophysics is the field that "studies the nature of the Sun, and how it influences the very nature of space - and, in turn, the atmospheres of planetary bodies and the technology that exists there." However, NASA's Heliophysics Division tends to limit study of planetary magnetospheres and atmospheres to only those of Earth. This leaves exploration and understanding of space plasma physics at other worlds to the purview of the Planetary Science and Astrophysics Divisions. This is detrimental to the study of space plasma physics in general since, although some cross-divisional funding opportunities do exist, vital elements of space plasma physics can be best addressed by extending the expertise of Heliophysics scientists to other stellar and planetary magnetospheres. However, the diverse worlds within the solar system provide crucial environmental conditions that are not replicated at Earth but can provide deep insight into fundamental space plasma physics processes. Studying planetary systems with Heliophysics objectives, comprehensive instrumentation, and new grant opportunities for analysis and modeling would enable a novel understanding of fundamental and universal processes of space plasma physics. As such, the Heliophysics community should be prepared to consider, prioritize, and fund dedicated Heliophysics efforts to planetary targets to specifically study space physics and aeronomy objectives

Space plasma physics science opportunities for the lunar orbital platform - Gateway

The Lunar Orbital Platform - Gateway (LOP - Gateway, or simply Gateway) is a crewed platform that will be assembled and operated in the vicinity of the Moon by NASA and international partner organizations, including ESA, starting from the mid-2020s. It will offer new opportunities for fundamental and applied scientific research. The Moon is a unique location to study the deep space plasma environment. Moreover, the lunar surface and the surface-bounded exosphere are interacting with this environment, constituting a complex multi-scale interacting system. This paper examines the opportunities provided by externally mounted payloads on the Gateway in the field of space plasma physics, heliophysics and space weather, and also examines the impact of the space environment on an inhabited platform in the vicinity of the Moon. It then presents the conceptual design of a model payload, required to perform these space plasma measurements and observations. It results that the Gateway is very well-suited for space plasma physics research. It allows a series of scientific objectives with a multi-disciplinary dimension to be addressed