Magnetic fields and charged particles around major planets and their satellites

1981 ◽  
Vol 303 (1477) ◽  
pp. 247-260 ◽  
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
Small Volume ◽  
Magnetic Moments ◽  
Charged Particles ◽  
The Moon ◽  
Planetary Rotation ◽  
Spacecraft Data ◽  
Insight Into

Jupiter and Saturn have magnetospheres whose large-scale structure can be understood by analogy with Earth, but the ways in which the magnetospheres differ are of great interest. At Earth, large-scale processes are dominated by convective plasma flows driven by the solar wind. At Jupiter, centrifugal effects driven by planetary rotation are critical. Magnetosphere particle sources include not only the ionosphere and the solar wind (as at Earth) but also satellites and rings. The internal planetary magnetic moments that control the scale of the magnetosphere differ by orders of magnitude between Jupiter and Earth. The magnetic moments have been modelled from spacecraft data but the restricted spatial sampling biases the results and limits confidence in details of the models. Because Jupiter is the only accessible protostar, it serves as a laboratory to test how well inferences from ground-based observations accord with in situ measurements. The agreement in some cases examined is reassuringly good but remote observations probe less than 0.1 % of the magnetospheric volume. Within that small volume, strong currents couple the moon lo with Jupiter s ionosphere. Voyager data give new insight into the lo story and suggest that lo may itself be magnetized and surrounded by an entirely unfamiliar type of magnetosphere.

Prospective White-light Imaging and In Situ Measurements of Quiescent Large-scale Solar-wind Streams from the Parker Solar Probe and Solar Orbiter

2018 ◽  
Vol 868 (2) ◽  
pp. 137 ◽  
Author(s):  
Ming Xiong ◽  
Jackie A. Davies ◽  
Xueshang Feng ◽  
Bo Li ◽  
Liping Yang ◽  
...  
Keyword(s):  
Solar Wind ◽  
White Light ◽  
Large Scale ◽  
In Situ Measurements ◽  
White Light Imaging

scholarly journals Remotely distinguishing and mapping endogenic water on the Moon

2017 ◽  
Vol 375 (2094) ◽  
pp. 20150391 ◽  
Author(s):  
Rachel L. Klima ◽  
Noah E. Petro
Keyword(s):  
Solar Wind ◽  
Spatial Distribution ◽  
Solar System ◽  
The Moon ◽  
Testing Hypotheses ◽  
Origin And Evolution ◽  
Lunar Interior ◽  
Geological Features ◽  
Insight Into

Water and/or hydroxyl detected remotely on the lunar surface originates from several sources: (i) comets and other exogenous debris; (ii) solar-wind implantation; (iii) the lunar interior. While each of these sources is interesting in its own right, distinguishing among them is critical for testing hypotheses for the origin and evolution of the Moon and our Solar System. Existing spacecraft observations are not of high enough spectral resolution to uniquely characterize the bonding energies of the hydroxyl molecules that have been detected. Nevertheless, the spatial distribution and associations of H, OH − or H 2 O with specific lunar lithologies provide some insight into the origin of lunar hydrous materials. The global distribution of OH − /H 2 O as detected using infrared spectroscopic measurements from orbit is here examined, with particular focus on regional geological features that exhibit OH − /H 2 O absorption band strengths that differ from their immediate surroundings. This article is part of the themed issue ‘The origin, history and role of water in the evolution of the inner Solar System’.

scholarly journals MESSENGER observations of planetary ion enhancements at Mercury’s northern magnetospheric cusp during Flux Transfer Event Showers

2021 ◽  
Author(s):  
Weijie Sun ◽  
James Slavin ◽  
Anna Milillo ◽  
Ryan Dewey ◽  
Stefano Orsini ◽  
...  
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
Transfer Event ◽  
Order Of Magnitude ◽  
In Situ Observations ◽  
Flux Transfer ◽  
Magnetospheric Cusp ◽  
Upward Moving ◽  
Entry Layer

Abstract At Mercury, several processes can release ions and neutrals out of the planet’s surface. Here we present enhancements of dayside planetary ions in the solar wind entry layer during flux transfer event (FTE) “showers” near Mercury’s northern magnetospheric cusp. In this entry layer, solar wind ions are accelerated and move downward (i.e. planetward) toward the cusps, which sputter upward-moving planetary ions within 1 minute. The precipitation rate is enhanced by an order of magnitude during FTE showers and the neutral density of the exosphere can vary by >10% due to this FTE-driven sputtering. These in situ observations of enhanced planetary ions in the entry layer likely correspond to an escape channel of Mercury’s planetary ions, and the large-scale variations of the exosphere observed on minute-timescales by ground-based telescopes. Comprehensive, future multi-point measurements made by BepiColombo will greatly enhance our understanding of the processes contributing to Mercury’s dynamic exosphere and magnetosphere.

Comets: pre- and post-Halley

1991 ◽  
Vol 9 (2) ◽  
pp. 219-224
Author(s):  
K. S. Krishna Swamy
Keyword(s):  
Solar Wind ◽  
Intensive Study ◽  
Cometary Plasma ◽  
Comet Halley ◽  
Insight Into

AbstractThe recent intensive study of Comet Halley based on in situ measurements, observations carried out with rockets and satellites and supplemented with co-ordinated Earth based observations has not only confirmed pre-Halley results, but also has given new insight into the nature of the nucleus, dust, gas and the interaction of cometary plasma with the solar wind. These observations also have raised many new questions and problems. Several of these aspects will be discussed. For a better understanding of these problems, the planned future missions to comets will also be discussed.

Large-scale electron solar wind parameters of the inner heliosphere with Parker Solar Probe/FIELDS

2020 ◽  
Author(s):  
Karine Issautier ◽  
Mingzhe Liu ◽  
Michel Moncuquet ◽  
Nicole Meyer-Vernet ◽  
Milan Maksimovic ◽  
...  
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
Statistical Study ◽  
Solar Wind Speed ◽  
The Sun ◽  
Solar Wind Parameters ◽  
Power Law Index ◽  
Probe Mission ◽  
Inner Heliosphere

<p>We present in situ properties of electron density and temperature in the inner heliosphere obtained during the three first solar encounters at 35 solar radii of the Parker Solar Probe mission. These preliminary results, recently shown by Moncuquet et al., ApJS, 2020, are obtained from the analysis of the plasma quasi-thermal noise (QTN) spectrum measured by the radio RFS/FIELDS instrument along the trajectories extending between 0.5 and 0.17 UA from the Sun, revealing different states of the emerging solar wind, five months apart. The temperature of the weakly collisional core population varies radially with a power law index of about -0.8, much slower than adiabatic, whereas the temperature of the supra-thermal population exhibits a much flatter radial variation, as expected from its nearly collisionless state. These measured temperatures are close to extrapolations towards the Sun of Helios measurements.</p><p>We also present a statistical study from these in situ electron solar wind parameters, deduced by QTN spectroscopy, and compare the data to other onboard measurements. In addition, we focus on the large-scale solar wind properties. In particular, from the invariance of the energy flux, a direct relation between the solar wind speed and its density can be deduced, as we have already obtained based on Wind continuous in situ measurements (Le Chat et al., Solar Phys., 2012). We study this anti-correlation during the three first solar encounters of PSP.</p>

Implantation of ions escaping the atmosphere of Mars within the regolith of Phobos, and Phobos’ surface ion weathering

2020 ◽  
Author(s):  
Quentin Nénon ◽  
Andrew R Poppe ◽  
Ali Rahmati ◽  
James P McFadden
Keyword(s):  
Solar Wind ◽  
Atomic Oxygen ◽  
The Moon ◽  
Ion Composition ◽  
Atmospheric Escape ◽  
The Past ◽  
Lunar Samples ◽  
Singly Charged

<p>Mars has lost and is losing its atmosphere into space. Strong evidences of this come from the observation of planetary singly charged heavy ions (atomic oxygen, molecular oxygen, carbon dioxide ions) by Mars Express and MAVEN. Phobos, the closest moon of Mars, orbits only 6,000 kilometers above the red planet’s surface and is therefore a unique vantage point of the planetary atmospheric escape, with the escaping ions being implanted within the regolith of Phobos and altering the properties of the moon’s surface.</p> <p>In this presentation, we aggregate all ion observations gathered in-situ close to the orbit of Phobos by three ion instruments onboard MAVEN, from 2015 to 2019, to constrain the long-term averaged ion environment seen by the Martian moon at all longitudes along its orbit. In particular, the SupraThermal and Thermal Ion Composition (STATIC) instrument onboard MAVEN distinguishes between solar wind and planetary ions. The newly constrained long-term ion environment seen by Phobos is combined with numerical simulations of ion transport and effects in matter.</p> <p>This way, we find that planetary ions are implanted on the near side of Phobos (pointing towards Mars) inside the uppermost tens of nanometers of regolith grains. The composition of near-side grains that may be sampled by future Phobos sample return missions is therefore not only contaminated by planetary ions, as seen in lunar samples with the terrestrial atmosphere, but may show a unique record of the past atmosphere of Mars.</p> <p>The long-term fluxes of planetary ions precipitating onto Phobos are so intense that these ions weather the moon’s surface as much as or more than solar wind ions. In particular, Martian ions accelerate the long-term sputtering and amorphization of the near side regolith by a factor of 2. Another implication is that ion weathering is highly asymmetric between the near side and far side of Phobos.</p>

scholarly journals The solar wind angular-momentum flux observed during Solar Orbiter's first orbit

2021 ◽  
Author(s):  
Daniel Verscharen ◽  
David Stansby ◽  
Adam Finley ◽  
Christopher Owen ◽  
Timothy Horbury ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Angular Momentum ◽  
Momentum Flux ◽  
Large Scale ◽  
Magnetic Field Data ◽  
Proton Data ◽  
Scale Properties ◽  
Orbiter Mission

<p>The Solar Orbiter mission is currently in its cruise phase, during which the spacecraft's in-situ instrumentation measures the solar wind and the electromagnetic fields at different heliocentric distances. </p><p>We evaluate the solar wind angular-momentum flux by combining proton data from the Solar Wind Analyser (SWA) Proton-Alpha Sensor (PAS) and magnetic-field data from the Magnetometer (MAG) instruments on board Solar Orbiter during its first orbit. This allows us to evaluate the angular momentum in the protons in addition to that stored in magnetic-field stresses, and compare these to previous observations from other spacecraft. We discuss the statistical properties of the angular-momentum flux and its dependence on solar-wind properties. </p><p>Our results largely agree with previous measurements of the solar wind’s angular-momentum flux in the inner heliosphere and demonstrate the potential for future detailed studies of large-scale properties of the solar wind with the data from Solar Orbiter.</p>

Evolution of Turbulence in the Kelvin–Helmholtz Instability mediated by the Magnetopause and its Boundary Layer

2020 ◽  
Author(s):  
Francesca Di Mare ◽  
Luca Sorriso-Valvo ◽  
Alessandro Retino' ◽  
Francesco Malara ◽  
Hiroshi Hasegawa
Keyword(s):  
Boundary Layer ◽  
Solar Wind ◽  
Large Scale ◽  
Velocity Shear ◽  
Helmholtz Instability ◽  
Intermittent Turbulence ◽  
Large Scale Structures ◽  
Developed Turbulence ◽  
Spacecraft Data ◽  
Efficient Transfer

<p>The turbulence at the interface between the solar wind and the Earth’s magnetosphere, mediated by the magnetopause and its boundary layer are investigated by using Geotail and THEMIS spacecraft data during ongoing Kelvin-Helmholtz instability (KHI). The efficient transfer of energy across scales for which the turbulence is responsible, achieves the connection between the macroscopic flow and the microscopic dissipation of this energy. This boundary layer is thought to be the result of the observed plasma transfer, driven by the development of the KHI, originating from the velocity shear between the solar wind and the almost static near-Earth plasma. A collection of 20 events spatially located on the tail-flank magnetopause, selected from previously studied by Hasegawa et al. 2006 and Lin et al. 2014, have been tested against standard diagnostics for intermittent turbulence. In light of the results obtained, we have investigated the behaviour of several parameters as a function of the progressive departure along the Geocentric Solar Magnetosphere coordinates, which roughly represent the direction in which we expect the KHI vortices to evolve towards fully developed turbulence. It appears that a fluctuating behaviour of the parameters exist, visible as a decreasing, quasi-periodic modulation with an associated periodicity, estimated to correspond to approximately 6.4 Earth Radii. Such observed wavelength is consistent with the estimated vortices roll-up wavelength reported in the literature for these events. If the turbulence is pre-existent, it is possible that the KHI modulates its properties along the magnetosheath, as we observed. On the other hand, if we assume that the KHI has been initiated near the magnetospheric nose and develops along the flanks, then the different intervals we study may be sampling the plasma at different stages of evolution of the KH-generated turbulence, after the instability has injected energy in a cascading process as large-scale structures.</p>

scholarly journals Solar wind ion trends and signatures: STEREO PLASTIC observations approaching solar minimum

2009 ◽  
Vol 27 (10) ◽  
pp. 3909-3922 ◽  
Author(s):  
A. B. Galvin ◽  
M. A. Popecki ◽  
K. D. C. Simunac ◽  
L. M. Kistler ◽  
L. Ellis ◽  
...  
Keyword(s):  
Solar Wind ◽  
Solar Minimum ◽  
Large Scale ◽  
Slow Solar Wind ◽  
Transient Event ◽  
Large Scale Structures ◽  
Close Proximity ◽  
Scale Structures

Abstract. STEREO has now completed the first two years of its mission, moving from close proximity to Earth in 2006/2007 to more than 50 degrees longitudinal separation from Earth in 2009. During this time, several large-scale structures have been observed in situ. Given the prevailing solar minimum conditions, these structures have been predominantly coronal hole-associated solar wind, slow solar wind, their interfaces, and the occasional transient event. In this paper, we extend earlier solar wind composition studies into the current solar minimum using high-resolution (1-h) sampling times for the charge state analysis. We examine 2-year trends for iron charge states and solar wind proton speeds, and present a case study of Carrington Rotation 2064 (December 2007) which includes minor ion (He, Fe, O) kinetic and Fe composition parameters in comparison with proton and magnetic field signatures at large-scale structures observed during this interval.

Aurora in Planetary Atmospheres

2020 ◽  
Author(s):  
Steve Miller
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar System ◽  
Magnetic Moment ◽  
Interplanetary Space ◽  
Magnetic Moments ◽  
Charged Particles ◽  
High Energy ◽  
Atoms And Molecules ◽  
Electrically Charged

Planetary aurorae are some of the most iconic and brilliant (in all senses of the word) indicators that not only are we all interconnected on our own planet Earth, but that we are connected throughout the entire solar system as well. They are testimony to the centrality of the Sun, not just in providing the essential sunlight that drives weather systems and makes habitability possible, but in generating a high-velocity wind of electrically charged particles—known as the solar wind—that buffets each of the planets in turn as it streams outward through interplanetary space. In some cases, those solar-wind particles actually cause the aurorae; in others, their pressure prompts and modifies what is already happening within the planetary system as a whole. Aurorae are created when electrically charged particles—predominantly negatively charged electrons or positive ions such as protons, the nuclei of hydrogen—crash into the atoms and molecules of a “planetary” atmosphere. They are guided and accelerated to high energies by magnetic field lines that tend to concentrate them toward the (magnetic) poles. Possessing energies usually measured in hundreds and thousands, all the way up to many millions, of electron Volts (eV), these energetic particles excite the atoms and molecules that constitute the atmosphere. At these energies, such particles can excite the electrons in atoms and molecules from their ground state to higher levels. The atoms and molecules that have been excited by these high-energy collisions can then relax, emitting light immediately after the collision, or after they have been “thermalized” by the surrounding atmosphere. Either way, the emitted radiation is at certain well-defined wavelengths, giving characteristic colors to the aurorae. Just how many particles, how much atmosphere, and what strength of magnetic field are required to create aurorae is an open question. Earth has a moderately sized magnetic field, with a magnetic moment measured at 7.91x1015 Tesla m3 (T m3). It has a moderate atmosphere, too, giving a standard sea-level pressure of 101,325 Pascal (Pa), or 1.01325 bar. The density of the solar wind at Earth is about 6 million per cubic meter (6x106 m-3). Earth has very bright aurorae. Mercury has a magnetic moment 0.7% of that of Earth and no atmosphere to speak of, and consequently no aurorae. But aurorae have been reported on both Venus and Mars, even though they both have surface magnetic fields much less than Mercury: they both have atmospheres, albeit Mars is very rarefied. The giant planets—Jupiter, Saturn, Uranus, and Neptune—have magnetic moments tens, hundreds, and (in the case of Jupiter) thousands of times that of Earth. They all have thick atmospheres, and all of them have aurorae (although Neptune’s has not been seen since the days of the Voyager spacecraft). The aurorae of the solar system are very varied, variable, and exciting.

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