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Moon-magnetosphere interactions result from the encounter between a magnetospheric plasma flow and moons, which act as obstacles to the plasma flow. In the Jovian magnetosphere, the Galilean moons orbit with a Keplerian velocity much slower than the plasma velocity, driven in near corotation by the planetary magnetic field. Therefore, they disturb the magnetospheric plasma flow, which in turn generates Alfvén waves in their close environments. These waves propagate along the magnetic field lines, accelerating particles and triggering auroral emissions in the giant planet atmosphere.Since August 2016, the Juno mission has made it possible to characterize in-situ the moon-magnetosphere interactions. Several crossings of the flux tubes connected to the orbits of the Galilean moons have been reported, revealing a diversity of particle properties and acceleration processes. However, Europa-magnetosphere interaction, whose remote and in-situ signatures are weaker and more difficult to identify than those of Io, remain poorly known.We characterize the precipitating electrons accelerated in the Europa-magnetosphere interaction by analyzing in-situ measurements and remote sensing observations recorded during 10 crossings of the flux tubes connected to Europa's auroral footprint tail by Juno. The electron downward energy flux exhibits an exponential decay as a function of down-tail distance from Europa's main auroral spot, with an e-folding factor of 7.2°. Electrons are accelerated at energies between 0.3 and 25 keV, with a characteristic energy that decreases down‐tail. We show that in the near tail (∆λFrac < 6°), acceleration is due, at least in part, to electrostatic processes while in the far tail (∆λFrac > 6°) broadband energy spectra are evidence for Alfvénic acceleration. The size of the interaction region at the equator is estimated to be 4.5 Europa radii, consistent with previous estimates based on theory and UV observations.

Pix.PAN is a compact cylindrical magnetic spectrometer, intended to provide excellent high energy particle measurements under high rate and hostile operating conditions in space. Its principal design is composed of 2 Halbach-array magnetic sectors and 6 Timepix4-based tracking layers; the latest hybrid silicon pixel detector readout ASIC designed. Due to Pix.PAN's compact and relatively simple design, it has the potential to be used for space missions exploring with measurements of unprecedented precision, high energy particles in radiation belts and the heliophere (solar energetic particles, anomalous and galactic cosmic rays). In this white paper, we discuss the design and expected performance of Pix.PAN for COMPASS (Comprehensive Observations of Magnetospheric Particle Acceleration, Sources, and Sinks), a mission concept submitted to NASA’s Call "B.16 Heliophysics Mission Concept Studies (HMCS)" in 2021 that targets the extreme high energy particle environment of Jupiter's inner radiation belts. We also discuss PixPAN's operational conditions and interface requirements. The conceptual design shows that is possible to achieve an energy resolution of

When a planet has an orbiting moon, atoms and molecules that escape the planetary atmosphere as ions and are accelerated into space may be implanted and preserved inside the moon’s surface. Here, we determine the long-term averaged anisotropy of ions escaping the atmosphere of Mars and impacting its moon Phobos from more than four years of in situ ion observations. These measurements are used to quantify an estimate of the average flux of ions that has been impacting each location on Phobos over geologic timescales. We find that the flux of bombarding Martian ions is highly asymmetric on the moon’s surface, as the nearside of Phobos sees a flux higher by a factor of 15 to 100 than its farside. We show that a first consequence of this is that Martian atmospheric oxygen, carbon, nitrogen and argon atoms are implanted and may be preserved inside the uppermost hundreds of nanometres of Phobos’s nearside regolith grains, which may be brought back to Earth by future sample return missions. The second effect is that alteration of the regolith properties is asymmetric on Phobos’s surface, as Martian ions accelerate weathering of the nearside by a factor of ~2. Martian atmospheric atoms are implanted in and alter regolith grains on the nearside surface of Phobos, according to an analysis of observations of ion escape from Mars’s atmosphere.

Jupiter is surrounded by intense and energetic radiation belts, yet most of the available in-situ data, in volume and quality, were taken outside of Europa's orbit, where radiation conditions are n...

This study examines the bombardment of energetic magnetospheric electrons onto Ganymede as a function of Jovian magnetic latitude. We use the output from a hybrid model to constrain features of the electromagnetic environment during the G1, G8, and G28 Galileo encounters when Ganymede was far above, within, or far below Jupiter's magnetospheric current sheet, respectively. To quantify electron fluxes, we use a test-particle model and trace electrons at discrete energies between 4.5 keV ≤ E ≤ 100 MeV while exposed to these fields. For each location with respect to Jupiter's current sheet, electrons of all energies bombard Ganymede's poles with average number and energy fluxes of 1·108 cm-2 s-1 and 3·109 keV cm-2 s-1, respectively. However, precipitation is inhomogeneous: poleward of the open-closed field line boundary, fluxes are enhanced in the trailing (but reduced in the leading) hemisphere. Within the Jovian current sheet, closed field lines of Ganymede's mini-magnetosphere shield electrons below 40 MeV from accessing the equator. Above these energies, equatorial fluxes are longitudinally inhomogeneous between the sub- and anti-Jovian hemispheres, but the averaged number flux (4·103 cm-2 s-1) is comparable to the flux deposited by each of the dominant energetic ion species near Ganymede. When outside of the Jovian current sheet, electrons below 100 keV enter Ganymede's mini-magnetosphere via the downstream reconnection region and bombard the leading apex, while electrons of all energies are shielded from the trailing apex. Averaged over a synodic rotation, electron flux patterns agree with brightness features observed across Ganymede's polar and equatorial surface.

The lunar surface and the regolith that covers it are weathered by solar wind ions, which sputter atoms and molecules, participate to the creation of optically opaque particles, alter the regolith composition and create amorphous rims on regolith grains by displacing atoms inside the material. As protons and alpha particles dominate the density of solar wind ions, these two species may be the main contributors to ion weathering. However, the importance of solar wind minor ions heavier than alpha particles for the ion-induced alteration of airless body surfaces is an open debate. The fundamental question at stake is whether the variety of different minor ion species, their high masses, and their high charge states may overcome their low densities in the solar wind to enable them to significantly contribute to ion weathering processes. In this presentation, long-term effects which develop on geological time scales are investigated. To do so, the long-term averaged energy spectrum of thermal, suprathermal, and energetic solar wind ions is estimated by compiling and contrasting ion measurements gathered by the ACE, Wind, STEREO, ARTEMIS, and MAVEN missions. The long-term ion environment to which the lunar surface is exposed to in the solar wind is then convolved with Stopping and Range of Ions in Matter (SRIM) simulations. Combining these data and ion effect models, we find that solar wind minor ions significantly alter the lunar surface and airless body surfaces in general, as they contribute to 12% to 22% of the total sputtering and create 20% to 50% of atomic displacements at depths greater than 100 nanometers. This new approach therefore confirms that solar wind minor ions play an important role in ion weathering of airless surfaces throughout the Solar System.

This study examines the bombardment of energetic magnetospheric electrons onto Ganymede as a function of Jovian magnetic latitude. We use the output from a three-dimensional, hybrid model to constr ...

The ion radiation belts just above the surface of the giant planets Jupiter and Saturn have recently been observed for the first time with Juno and Cassini. The relevant physical processes differ from Earth’s inner proton belt. Jupiter’s innermost ion belt consists of protons, oxygen, and sulfur ions. A comparison of Juno particle and plasma data with numerical modeling supports that these ions are occasionally transported from the magnetosphere across the main ring of Jupiter. It has been suggested earlier that this ring is populated through the stripping of energetic neutral atoms that are produced in the magnetosphere. This process is found to be too slow to populate the belt. After radial transport, the new ions lose energy in the tenuous ring halo inward of the main ring. This gives rise to an unusual spectral shape that rises from 100keV to 1MeV. Neutralization of the ions in the ring grains acts slower and eventually removes Saturn’s innermost belt differs from Jupiter’s and Earth’s inner belts in the sense that Saturn’s rings are too dense and extended to allow radial transport of magnetospheric ions into the innermost belt. Saturn’s ion belts are therefore thought to be exclusively populated by cosmic ray tertiary particles from the CRAND process. While the source is different, the losses are similar as at Jupiter, namely interaction with the tenuous D-ring and the planetary exosphere. This interaction shows in the proton pitch angle distribution and has been used to constrain the scale height of Saturn’s exosphere that is difficult to do otherwise.

Phobos is the closest of the two moons of Mars and its surface is not only exposed to ions coming from the solar wind (mainly protons H+ and alpha particles He++), but is also bombarded by ions coming from Mars itself (mainly atomic and molecular oxygen ions O+ and O2+). Space weathering at Phobos would be intimately linked to the planetary atmospheric escape if Martian ions significantly alter the properties of the moon’s surface.In this presentation, the long-term averaged ion environment seen by the surface of Phobos (omnidirectional and directional fluxes, and composition) is constructed from 4 years of ion measurements gathered in-situ by the NASA MAVEN mission. The MAVEN spacecraft repeatedly crossed the orbit of Phobos from January 2015 to February 2019 and was uniquely suited to unprecedently observe ions there with its three ion instruments: SWIA, STATIC, and SEP. These three experiments together constrain the entire range of ion kinetic energies that impact Phobos, from cold ions of a few eV to solar energetic ions of several MeV. In addition, the STATIC instrument (1 eV to 30 keV) is able to discriminate the mass of the observed ions by measuring their time-of-flight. This capability is important to understand the weathering of the surface of Phobos, as for instance the effect on the surface of a precipitating heavy molecular oxygen ion is significantly different from the one of a proton.The relative importance of Martian and solar wind ions is in turn assessed from the observed ion omnidirectional fluxes for two space weathering effects: (1) surface sputtering, which is computed by using ion specie and energy-dependent sputtering yields available in the literature and (2) the production of vacancies inside the regolith grains, which is estimated with the SRIM software. (1) We find that Martian ions dominate solar wind ions in sputtering the surface of Phobos when the moon crosses the Martian magnetotail. We also reveal that molecular oxygen O2+ ions sputter as much as or more from the surface of Phobos than atomic O+ ions. (2) Martian heavy ions significantly contribute to the production of vacancies in the uppermost nanometer of Phobos regolith grains. Finally, MAVEN directional flux measurements are used to study the anisotropy of the bombarding ion fluxes at Phobos, which we find implies an asymmetric weathering of the surface: the near side (always facing Mars) is primarily weathered by Martian ions, whereas the far side is primarily altered by solar wind ions.

The high kinetic energy electrons that populate the Earth's radiation belts emit synchrotron emissions because of their interaction with the planetary magnetic field. A lunar near side array would be uniquely positioned to image this emission and provide a near real time measure of how the Earth's radiation belts are responding to the current solar input. The Salammbo code is a physical model of the dynamics of the three-dimensional phase-space electron densities in the radiation belts, allowing the prediction of 1 keV to 100 MeV electron distributions trapped in the belts. This information is put into a synchrotron emission simulator which provides the brightness distribution of the emission up to 1 MHz from a given observation point. Using Digital Elevation Models from Lunar Reconnaissance Orbiter (LRO) Lunar Orbiter Laser Altimeter (LOLA) data, we select a set of locations near the Lunar sub-Earth point with minimum elevation variation over various sized patches where we simulate radio receivers to create a synthetic aperture. We consider all realistic noise sources in the low frequency regime. We then use a custom CASA code to image and process the data from our defined array, using SPICE to align the lunar coordinates with the Earth. We find that for a moderate lunar surface electron density of 250/cm^3, the radiation belts may be detected every 12-24 hours with a 16384 element array over a 10 km diameter circle. Changing electron density can make measurements 10x faster at lunar night, and 10x slower at lunar noon., Comment: 23 pages plus references. 3 Tables, 6 Figures

This whitepaper identifies important science questions that can be answered through exploration of the Jupiter System, with emphasis on the questions that can be addressed by the Europa Clipper Mission. We advocate for adding Jupiter System Science to the mission after launch when expanding the scientific scope will not affect the development cost., Comment: White Paper submitted to the Astrobiology and Planetary Science Decadal Survey

Jupiter has the most complex and energetic radiation belts in our Solar System and one of the most challenging space environments to measure and characterize in-depth. Their hazardous environment is also a reason why so many spacecraft avoid flying directly through their most intense regions, thus explaining how Jupiter’s radiation belts have kept many of their secrets so well hidden, despite having been studied for decades. In this paper we argue why these secrets are worth unveiling. Jupiter’s radiation belts and the vast magnetosphere that encloses them constitute an unprecedented physical laboratory, suitable for interdisciplinary and novel scientific investigations: from studying fundamental high energy plasma physics processes which operate throughout the Universe, such as adiabatic charged particle acceleration and nonlinear wave-particle interactions, to exploiting the astrobiological consequences of energetic particle radiation. The in-situ exploration of the uninviting environment of Jupiter’s radiation belts presents us with many challenges in mission design, science planning, instrumentation, and technology. We address these challenges by reviewing the different options that exist for direct and indirect observations of this unique system. We stress the need for new instruments, the value of synergistic Earth and Jupiter-based remote sensing and in-situ investigations, and the vital importance of multi-spacecraft in-situ measurements. While simultaneous, multi-point in-situ observations have long become the standard for exploring electromagnetic interactions in the inner Solar System, they have never taken place at Jupiter or any strongly magnetized planet besides Earth. We conclude that a dedicated multi-spacecraft mission to Jupiter is an essential and obvious way forward for exploring the planet’s radiation belts. Besides guaranteeing numerous discoveries and huge leaps in our understanding of radiation belt systems, such a mission would also enable us to view Jupiter, its extended magnetosphere, moons, and rings under new light, with great benefits for space, planetary, and astrophysical sciences. For all these reasons, in-situ investigations of Jupiter’s radiation belts deserve to be given a high priority in the future exploration of our Solar System. This article is based on a White Paper submitted in response to the European Space Agency’s call for science themes for its Voyage 2050 programme.

International audience

Permanently shadowed regions (PSRs) inside lunar polar craters likely harbor volatiles which are of great interest for both science and resource utilization. The origin and evolution of this resource is in part driven by external space weathering, including the bombardment by space plasma ions. Previous work has investigated the flux of horizontal solar wind ions that are deflected into lunar polar craters by plasma wake electrostatic fields. Here, we constrain the flux of ions that travel northward or southward in the natural environment encountered by the Moon along its orbit. Using 9 years of in situ ion measurements gathered by the ARTEMIS mission, we find that all locations inside lunar craters are altered by a flux of out-of-ecliptic ions of 10−3 times the solar wind flux. In particular, the central floor of Shackleton’s crater is weathered by a non-null ion flux. The origin of northward and southward ions impacting the Moon is identified as (i) shocked thermalized solar wind ions in the terrestrial magnetosheath and (ii) the isotropic component of ion distributions in the terrestrial magnetotail. The energy spectrum of out-of-ecliptic ions is found to be flatter than the solar wind spectrum. Thus, sputtering of pure water ice irradiated by out-of-ecliptic ions would be created for more than 30% by >3 keV protons, unlike equatorial locations that are mostly sputtered by 1 keV protons. Future work may investigate the influence of the low, but nonzero flux of out-of-ecliptic ions reported here on the budget of volatiles in lunar PSRs.

The Cameras for Allsky Meteor Surveillance (CAMS) video-based meteoroid orbit survey adds 60 newly identified showers to the IAU Working List of Meteor Showers (numbers 427, 445–446, 506–507, and part of 643–750). 28 of these are also detected in the independent SonotaCo survey. In total, 230 meteor showers and shower components are identified in CAMS data, 177 of which are detected in at least two independent surveys. From the power-law size frequency distribution of detected showers, we extrapolate that 36% of all CAMS-observed meteors originated from ∼700 showers above the N = 1 per 110,000 shower limit. 71% of mass falling to Earth from streams arrives on Jupiter-family type orbits. The transient Geminids account for another 15%. All meteoroids not assigned to streams form a sporadic background with highest detected numbers from the apex source, but with 98% of mass falling in from the antihelion source. Even at large ∼7-mm sizes, a Poynting–Robertson drag evolved population is detected, which implies that the Grun et al. collisional lifetimes at these sizes are underestimated by about a factor of 10. While these large grains survive collisions, many fade on a 10 4 -y timescale, possibly because they disintegrate into smaller particles by processes other than collisions, leaving a more resilient population to evolve. The meteors assigned to the various showers are identified in the CAMS Meteoroid Orbit Database 2.0 submitted to the IAU Meteor Data Center, and can be accessed also at http://cams.seti.org .

Leading up to the 2015 IAU General Assembly, the International Astronomical Union’s Working List of Meteor Showers included 486 unconfirmed showers, showers that are not certain to exist. If confirmed, each shower would provide a record of past comet or asteroid activity. Now, we report that 41 of these are detected in the Cameras for Allsky Meteor Surveillance (CAMS) video-based meteor shower survey. They manifest as meteoroids arriving at Earth from a similar direction and orbit, after removing the daily radiant drift due to Earth’s motion around the Sun. These showers do exist and, therefore, can be moved to the IAU List of Established Meteor Showers. This adds to 31 previously confirmed showers from CAMS data. For each shower, finding charts are presented based on 230,000 meteors observed up to March of 2015, calculated by re-projecting the drift-corrected Sun-centered ecliptic coordinates into more familiar equatorial coordinates. Showers that are not detected, but should have, and duplicate showers that project to the same Sun-centered ecliptic coordinates, are recommended for removal from the Working List.

From preliminary 2010–2011 results of the Cameras for Allsky Meteor Surveillance (CAMS) meteoroid orbit survey, which were combined with published 2007–2009 SonotaCo video meteor network data, 55 new meteor showers (##448–502) were identified and added to the IAU Working List on Meteor Showers in 2012. These showers were identified based on an automated single-linked D SH -criterion analysis of a combined 105,000 orbits with high-threshold (a low D SH V g > 40 km/s showers, 54% of the V g = 18–40 km/s showers, and 90% of the slow V g

The importance of solar wind minor ions heavier than alpha particles in weathering airless body surfaces is an open debate. The fundamental question at stake is whether the variety of different minor ion species, their high masses, and their high charge states may overcome their low densities in the solar wind to enable them to significantly contribute to ion weathering processes. Here, long-term effects that develop on geological timescales are investigated. To do so, the long-term averaged energy spectrum of thermal and suprathermal solar wind ions is estimated by compiling and contrasting ion measurements gathered by the Advanced Composition Explorer (ACE), Wind, Solar TErrestrial RElations Observatory (STEREO), ARTEMIS, and Mars Atmosphere and Volatile Evolution (MAVEN) missions. The long-term ion environment is then convolved with Stopping and Range of Ions in Matter simulations. Combining these data and models, we find that solar wind minor ions significantly alter airless body surfaces, as they contribute to 8%–14% of the total sputtering and create 20%–50% of atomic displacements at depths greater than 100 nm. The new approach presented in this article therefore confirms that solar wind minor ions play an important role in the ion weathering of airless surfaces throughout the solar system.

International audience; A modeling of the effect of the rings of Jupiter on trapped >3‐MeV electrons and protons is proposed. The effect is then added to the physical model Salammbô and discussed against in situ measurements obtained by the Pioneer 11 and Galileo Probe missions. It is first shown that there is no evidence of an effect of the rings on the Jovian radiation belts, thanks to the new internal magnetic field model proposed by the Juno mission. Two grain populations are then studied: small grains, with a radius lower than 100 μm, are shown to not affect observable >3‐MeV trapped particles. The normal optical depth of grains with a radius larger than 2 cm, which may exist in the main ring, is constrained to be lower than 10−7 by the Salammbô model.

International audience; A physical model of the Jovian trapped protons with kinetic energies higher than 1 MeV inward of the orbit of the icy moon Europa is presented. The model, named Salammbô, takes into account the radial diffusion process, the absorption effect of the Jovian moons, and the Coulomb collisions and charge exchanges with the cold plasma and neutral populations of the inner Jovian magnetosphere. Preliminary modeling of the wave‐particle interaction with electromagnetic ion cyclotron waves near the moon Io is also performed. Salammbô is validated against in situ proton measurements of Pioneer 10, Pioneer 11, Voyager 1, Galileo Probe, and Galileo Orbiter. A prominent feature of the MeV proton intensity distribution in the modeled area is the 2 orders of magnitude flux depletion observed in MeV measurements near the orbit of Io. Our simulations reveal that this is not due to direct interactions with the moon or its neutral environment but results from scattering of the protons by electromagnetic ion cyclotron waves.

Ground based low frequency radio interferometers have been developed in the last decade and are providing the scientific community with high quality observations. Conversely, current radioastronomy instruments in space have a poor angular resolution with single point observation systems. Improving the observation capabilities of the low frequency range (a few kHz to 100 MHz) requires to go to space and to set up a space based network of antenna that can be used as an interferometer. We present the outcome of the NOIRE (Nanosatellites pour un Observatoire Interf\'erom\'etrique Radio dans l'Espace / Nanosatellites for a Radio Interferometer Observatory in Space) study which assessed, with help of CNES PASO (Architecture Platform for Orbital Systems is CNES' cross-disciplinary team in charge of early mission and concept studies), the feasibility of a swarm of nanosatellites dedicated to a low frequency radio observatory. With such a platform, space system engineering and instrument development must be studied as a whole: each node is a sensor and all sensors must be used together to obtain a measurement. The study was conducted on the following topics: system principle and concept (swarm, node homogeneity); Space and time management (ranging, clock synchronization); Orbitography (Moon orbit, Lagrange point options); Telecommunication (between nodes and with ground) and networking; Measurements and processing; Propulsion; Power; Electromagnetic compatibility. No strong show-stopper was identified during the preliminary study, although the concept is not yet ready. Several further studies and milestones are identified. The NOIRE team will collaborate with international teams to try and build this next generation of space systems., Comment: Submitted to IEEEAeroconf 2018 proceedings

International audience; A new global physical model of the electron radiation belts of Jupiter inside the orbit of Europa is presented. It is an update of the Office National d'Etudes et de Recherches Aérospatiales model Salammbô proposed by Sicard and Bourdarie (2004) that now integrates a contribution of the wave-particle interaction above the orbit of Io. In addition, a revisited and more realistic boundary condition near Europa is implemented. The new Salammbô model is validated against the in situ flux measurements obtained by the Pioneer 10, Pioneer 11, and Voyager 1 missions. The role of the wave-particle interaction is discussed by investigating its effect on the predicted in situ fluxes. In particular, the interaction appears in our simulations as a strong pitch angle scattering process explaining the flux depletions intensities near the orbit of Io as well as the flux intensities near the spacecraft perijoves.

Context. Observing Jupiter's synchrotron emission from the Earth remains today the sole method to scrutinize the distribution and dynamical behavior of the ultra energetic electrons magnetically trapped around the planet (because in-situ particle data are limited in the inner magnetosphere). Aims. We perform the first resolved and low-frequency imaging of the synchrotron emission with LOFAR at 127 MHz. The radiation comes from low energy electrons (~1-30 MeV) which map a broad region of Jupiter's inner magnetosphere. Methods (see article for complete abstract) Results. The first resolved images of Jupiter's radiation belts at 127-172 MHz are obtained along with total integrated flux densities. They are compared with previous observations at higher frequencies and show a larger extent of the synchrotron emission source (>=4 $R_J$). The asymmetry and the dynamic of east-west emission peaks are measured and the presence of a hot spot at lambda_III=230 {\deg} $\pm$ 25 {\deg}. Spectral flux density measurements are on the low side of previous (unresolved) ones, suggesting a low-frequency turnover and/or time variations of the emission spectrum. Conclusions. LOFAR is a powerful and flexible planetary imager. The observations at 127 MHz depict an extended emission up to ~4-5 planetary radii. The similarities with high frequency results reinforce the conclusion that: i) the magnetic field morphology primarily shapes the brightness distribution of the emission and ii) the radiating electrons are likely radially and latitudinally distributed inside about 2 $R_J$. Nonetheless, the larger extent of the brightness combined with the overall lower flux density, yields new information on Jupiter's electron distribution, that may shed light on the origin and mode of transport of these particles., Comment: 10 pages, 12 figures, accepted for publication in A&A (27/11/2015) - abstract edited because of limited characters