記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.icarus.2024.116311

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.icarus.2024.116342

掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

Abstract

Although the Moon does not have a global intrinsic magnetic field, lunar crustal magnetic anomalies (LMAs) are nonuniformly distributed over the lunar surface. The interaction between the solar wind and LMAs leads to the formation of mini-magnetospheres. Since the spatial scales of LMAs are very small, below several tens of kilometers, solar wind ions are demagnetized while electrons are still magnetized, forming Hall electric fields typically at low altitudes ($$<\sim$$30 km). Since direct observations of these interaction regions are challenging from typical nominal altitudes of lunar orbiters ($$>\sim$$100 km), the solar wind-LMA interaction has not been fully understood. In this study, we analyze low-altitude data obtained by Kaguya over various LMAs to comprehensively characterize the plasma environment and electromagnetic fields in the solar wind-LMA interaction region. We observe strong solar wind ion reflection and whistler mode waves at 1–10 Hz under high solar wind dynamic pressure and strong interplanetary magnetic field conditions, respectively. These trends are particularly clear over spatially extended LMAs. Over both spatially isolated and extended LMAs, strong Broadband Electrostatic Noise at 1–10 kHz tends to be observed when the spacecraft is magnetically connected to the lunar surface. In addition, our results suggest that anti-moonward electrostatic fields at low altitudes contribute to the acceleration, deceleration, and reflection of incident solar wind particles, and the resulting modification of particle velocity distribution functions can strongly influence the nature of the solar wind-LMA interaction including plasma wave excitation. Based on Kaguya data, we also develop a predictable indicator of the central interaction region where solar wind ions and electrons are decoupled. We propose that this indicator can be utilized to define regions of interest for future low-altitude or lander missions to LMA.

Graphical Abstract

DOI： 10.1186/s40623-024-02123-3

Open Access

その他リンク： https://link.springer.com/article/10.1186/s40623-024-02123-3/fulltext.html

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

Abstract

In this study, we investigated terrestrial-origin O⁺ ions below 1 keV around the Moon using data from the Kaguya satellite between December 2007 and June 2009. These terrestrial-origin low-energy O⁺ ions were identified based on three parameters: the periodicity of O⁺ ion count enhancement corresponding to Kaguya’s 2-h orbital period, the count ratio of O⁺ ions to Na⁺ and Al⁺ ions, and the direction of ion bulk velocity in the Sun–Earth direction. We identified three intervals that included such O⁺ ions: 14:30–20:30 UT on June 19, 2008, 19:00 UT on July 16, 2008 to 03:00 UT on July 17, 2008, and 14:00–24:00 UT on June 7, 2009. These intervals were found in the dawn sector, the dusk sector, and the midnight to dawn sector within the magnetotail, respectively. We examined the relation between geomagnetic storm conditions and increases in terrestrial-origin O⁺ ion counts and found that all three intervals occurred during the late recovery phase of moderate/weak magnetic storms. Since moderately/weakly disturbed conditions (Dst = –40 nT to –20 nT) account for approximately 21% of the total time between 1957 and 2016, we suggest that low-energy O⁺ ions from the Earth have a non-negligible impact on the ion composition and the ion mass density in the lunar plasma environment.

Graphical abstract

DOI： 10.1186/s40623-024-02107-3

Open Access

その他リンク： https://link.springer.com/article/10.1186/s40623-024-02107-3/fulltext.html

記述言語：英語   掲載種別：研究論文（学術雑誌）  

<jats:title>Abstract</jats:title><jats:p>To investigate the excitation mechanism of ionospheric perturbations on Mars by the Neutral Gas and Ion Mass Spectrometer (NGIMS) onboard Mars Atmosphere and Volatile EvolutioN (MAVEN), we categorize ionospheric perturbations into three cases: (a) the ion‐neutral coupling cases where ion and neutral perturbations are well coupled, (b) the ion‐specific cases where ion perturbations move independently from neutrals, and (c) the coronal mass ejection cases associated with solar wind extreme events. A representative number of cases from total profiles are compared with a numerical model to determine the fraction that can be explained by an atmospheric gravity waves (GW). The neutral perturbations on the dayside at 170–190 km altitudes are in excellent agreement with the GW. Whereas, contrary to previous thoughts, neutral perturbations are not necessarily explained by the GW especially on the nightside at 190–210 km. Ion perturbations on the dayside at 170–190 km also show a good agreement with the GW. The agreement becomes extremely low on the nightside at 190–210 km, reaching the limit of strong ion‐neutral coupling around 190 km. Further investigation found that the behavior of the ion perturbations explicitly depends on the dayside and nightside. Its dominant driver potentially differs clearly between dayside and nightside. Statistics of relative perturbations demonstrate a clear effect associated with species scale height in neutrals. Whereas, the correlation between ions and neutrals breaks down at high solar zenith angle near southern dusk. We see currently unexplained behavior that cannot be fully interpreted by GW both at night and near southern dusk.</jats:p>

DOI： 10.1029/2024ja032988

Open Access

掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

DOI： 10.1038/s42005-024-01766-8

Open Access

その他リンク： https://www.nature.com/articles/s42005-024-01766-8

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

DOI： 10.48550/arXiv.2410.05913

掲載種別：研究論文（学術雑誌）  

<jats:title>Abstract</jats:title>
<jats:p>Mars lacks a global intrinsic dipole field but possesses localized crustal fields, making it unique in the solar system. Recent observations revealed that electrons can be injected into the crustal fields, and exhibit drift-dispersed bursts due to the magnetic drift motion, which are characterized by increases or decreases in energy over time in the energy spectrum. However, the source of the drift-dispersed electrons and the mechanism of their injection into the crustal fields remains unclear. Here, by leveraging data from the Mars Atmosphere and Volatile EvolutioN mission, along with test-particle simulations, we reveal that the source of dispersed electrons is the precipitating electrons injected into the crustal fields via open field lines. These electrons display as dispersionless bursts near the source location, and as dispersed bursts as they drift away from the source. Thus, the dispersed electrons represent a later stage in the evolution of dispersionless electrons. This evolutionary process closely mirrors that observed within Earth’s dipole field, affirming that the crustal fields function similarly to a mini-magnetosphere.</jats:p>

DOI： 10.3847/1538-4357/ad64d5

Open Access

掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPIE  

DOI： 10.1117/12.3017298

掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union (AGU)  

Abstract

Although solar wind‐driven convection is expected to dominate magnetospheric circulation at Mercury, its exact pattern remains poorly characterized by observations. Here we present BepiColombo Mio observations during the third Mercury flyby indicative of convection‐driven transport of low‐energy dense ions into the deep magnetosphere. During the flyby, Mio observed an energy‐dispersed ion population from the duskside magnetopause to the deep region of the midnight magnetosphere. A comparison of the observations with backward test particle simulations suggests that the observed energy dispersion structure can be explained in terms of energy‐selective transport by convection from the duskside tail magnetopause. We also discuss the properties and origins of more energetic ions observed in the more dipole‐like field regions of the magnetosphere in comparison to previously reported populations of the plasma sheet horn and ring current ions. Additionally, forward test particle simulations predict that most of the observed ions on the nightside will precipitate onto relatively low‐latitude regions of the nightside surface of Mercury for a typical convection case. The presented observations and simulation results reveal the critical role of magnetospheric convection in determining the structure of Mercury's magnetospheric plasma. The upstream driver dependence of magnetospheric convection and its effects on other magnetospheric processes and plasma‐surface interactions should be further investigated by in‐orbit BepiColombo observations.

DOI： 10.1029/2024ja032751

Open Access

掲載種別：研究論文（学術雑誌）   出版者・発行元：American Astronomical Society  

Abstract

Ion pickup by the solar wind is ubiquitous in space plasma. Because pickup ions are originally produced by ionization of an exospheric neutral atmosphere, their measurements contain information on the exospheric neutral abundance. Here we established a method to retrieve exospheric number densities, by analyzing the ion velocity distribution functions of pickup ions measured by the Mars Atmosphere and Volatile EvolutioN spacecraft. We successfully retrieved exospheric oxygen density distributions at altitudes ranging from 1000 to 10,000 km around Mars except for the vicinity of the bow shock. This method can be applied to other space missions to study the upper atmosphere of planets, moons, and other small bodies in our solar system, where pickup ions exist.

DOI： 10.3847/psj/ad65d4

Open Access

その他リンク： https://iopscience.iop.org/article/10.3847/PSJ/ad65d4/pdf

掲載種別：研究論文（学術雑誌）   出版者・発行元：EDP Sciences  

Context. The Mercury electron analyzer (MEA) obtained new electron observations during the first three Mercury flybys by BepiColombo on October 1, 2021 (MFB1), June 23 , 2022 (MFB2), and June 19, 2023 (MFB3). BepiColombo entered the dusk side magnetotail from the flank magnetosheath in the northern hemisphere, crossed the Mercury solar orbital equator around midnight in the magnetotail, traveled from midnight to dawn in the southern hemisphere near the closest approach, and exited from the post-dawn magnetosphere into the dayside magnetosheath.

Aims. We aim to identify the magnetospheric boundaries and describe the structure and dynamics of the electron populations observed in the various regions explored along the flyby trajectories.

Methods. We derive 4s time resolution electron densities and temperatures from MEA observations. We compare and contrast our new BepiColombo electron observations with those obtained from the Mariner 10 scanning electron spectrometer (SES) 49 yr ago.

Results. A comparison to the averaged magnetospheric boundary crossings of MESSENGER indicates that the magnetosphere of Mercury was compressed during MFB1, close to its average state during MFB2, and highly compressed during MFB3. Our new MEA observations reveal the presence of a wake effect very close behind Mercury when BepiColombo entered the shadow region, a significant dusk-dawn asymmetry in electron fluxes in the nightside magnetosphere, and strongly fluctuating electrons with energies above 100s eV in the dawnside magnetosphere. Magnetospheric electron densities and temperatures are in the range of 10–30 cm⁻³ and above a few 100s eV in the pre-midnight-sector, and in the range of 1–100 cm⁻³ and well below 100 eV in the post-midnight sector, respectively.

Conclusions. The MEA electron observations of different solar wind properties encountered during the first three Mercury flybys reveal the highly dynamic response and variability of the solar wind-magnetosphere interactions at Mercury. A good match is found between the electron plasma parameters derived by MEA in the various regions of the Hermean environment and similar ones derived in a few cases from other instruments on board BepiColombo.

DOI： 10.1051/0004-6361/202449450

Open Access

記述言語：英語   掲載種別：研究論文（学術雑誌）  

<jats:title>Abstract</jats:title><jats:p>Since 2021, a new surge in discrete aurora detections at Mars has been observed by the Emirates Mars Ultraviolet Spectrometer (EMUS) onboard the Emirates Mars Mission (EMM) Hope Orbiter as EMUS started to regularly obtain synoptic auroral images with a high sensitivity. Here we report on a fortuitous conjunction between EMM and Mars Express (MEX) using far ultraviolet (FUV) imaging of discrete aurora by EMM EMUS, in situ measurements of suprathermal electrons by the MEX Analyzer of Space Plasma and Energetic Atoms Electron Spectrometer (ELS), and topside radar sounding of the nightside ionosphere by the MEX Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS). In this event, EMM EMUS imaged a clear discrete aurora signature around moderately strong crustal magnetic fields on the nightside near the dusk terminator, 11 min before which MEX MARSIS measured a prominent local enhancement of the peak electron density in the nightside ionosphere and MEX ELS observed an in situ enhancement of suprathermal electrons at the corresponding location. A remarkable geographic agreement is found between the enhancements of the aurora, ionosphere, and suprathermal electrons, suggesting that the enhanced ionization and auroral emission are caused concurrently by precipitating suprathermal electrons. Subsequent images indicate that the discrete aurora slightly changed its shape in 15 min and mostly disappeared in a few hours. The MEX MARSIS measurements of the auroral ionosphere display overlapping ionospheric and surface echoes indicative of horizontal gradients of the peak electron density. Analysis of the overlapping echoes implies that the auroral ionosphere and electron precipitation could be highly structured with horizontal spatial scales on the order of several tens of km. MEX MARSIS also observed a non-auroral ionospheric enhancement with a wider spatial extent than the local auroral enhancement, suggesting alternative sources of the enhanced nightside ionosphere such as plasma transport. The comparison between the ionospheric structures measured by MEX MARSIS, suprathermal electron flux measured by MEX ELS, and discrete auroral emission imaged by EMM EMUS underscores the complexity of the auroral and non-auroral nightside ionospheres. This motivates further investigations of their sources, transport, and connections to the magnetotail dynamics of Mars.</jats:p>

DOI： 10.1186/s40623-024-02010-x

Open Access

掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

Abstract

On 10 August 2021, the Mercury-bound BepiColombo spacecraft performed its second fly-by of Venus and provided a short-lived observation of its induced magnetosphere. Here we report results recorded by the Mass Spectrum Analyzer on board Mio, which reveal the presence of cold O⁺ and C⁺ with an average total flux of ~4 ± 1 × 10⁴ cm⁻² s⁻¹ at a distance of about six planetary radii in a region that has never been explored before. The ratio of escaping C⁺ to O⁺ is at most 0.31 ± 0.2, implying that, in addition to atomic O⁺ ions, CO group ions or water group ions may be a source of the observed O⁺. Simultaneous magnetometer observations suggest that these planetary ions were in the magnetosheath flank in the vicinity of the magnetic pileup boundary downstream. These results have important implications regarding the evolution of Venus’s atmosphere and, in particular, the evolution of water on the surface of the planet.

DOI： 10.1038/s41550-024-02247-2

Open Access

その他リンク： https://www.nature.com/articles/s41550-024-02247-2

記述言語：英語   掲載種別：研究論文（学術雑誌）  

<jats:title>Abstract</jats:title><jats:p>Magnetic reconnection is a fundamental mechanism for the transport of mass and energy in planetary magnetospheres and astrospheres. While the process of reconnection is itself ubiquitous across a multitude of systems, the techniques used for its analysis can vary across scientific disciplines. Here we frame the latest understanding of reconnection theory by missions such as NASA’s Magnetospheric Multiscale (MMS) mission for use throughout the solar system and beyond. We discuss how reconnection can couple magnetized obstacles to both sub- and super-magnetosonic upstream flows. In addition, we address the need to model sheath plasmas and field-line draping around an obstacle to accurately parameterize the possibility for reconnection to occur. We conclude with a discussion of how reconnection energy conversion rates scale throughout the solar system. The results presented are not only applicable to within our solar system but also to astrospheres and exoplanets, such as the first recently detected exoplanet magnetosphere of HAT-11-1b.</jats:p>

DOI： 10.1007/s11214-023-01017-2

Open Access

掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

Abstract

Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are the surface composition, shape, morphology, and structure of the target object? What is the composition of the gas and dust in the coma, its connection to the nucleus, and the nature of its interaction with the solar wind? The mission was proposed to the European Space Agency in 2018, and formally adopted by the agency in June 2022, for launch in 2029 together with the Ariel mission. Comet Interceptor will take advantage of the opportunity presented by ESA’s F-Class call for fast, flexible, low-cost missions to which it was proposed. The call required a launch to a halo orbit around the Sun-Earth L2 point. The mission can take advantage of this placement to wait for the discovery of a suitable comet reachable with its minimum $\varDelta $V capability of $600\text{ ms}^{-1}$. Comet Interceptor will be unique in encountering and studying, at a nominal closest approach distance of 1000 km, a comet that represents a near-pristine sample of material from the formation of the Solar System. It will also add a capability that no previous cometary mission has had, which is to deploy two sub-probes – B1, provided by the Japanese space agency, JAXA, and B2 – that will follow different trajectories through the coma. While the main probe passes at a nominal 1000 km distance, probes B1 and B2 will follow different chords through the coma at distances of 850 km and 400 km, respectively. The result will be unique, simultaneous, spatially resolved information of the 3-dimensional properties of the target comet and its interaction with the space environment. We present the mission’s science background leading to these objectives, as well as an overview of the scientific instruments, mission design, and schedule.

DOI： 10.1007/s11214-023-01035-0

Open Access

その他リンク： https://link.springer.com/article/10.1007/s11214-023-01035-0/fulltext.html

掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union (AGU)  

Abstract

During the first flyby of the BepiColombo composite spacecraft at Mercury in October 2021 ion spectrometers observed two intense spectral lines with energies between 10 and 70 eV. The spectral lines persisted also at larger distances from Mercury and were observed again at lower intensity during cruise phase in March 2022 and at the second and third Mercury flyby as a single band. The ion composition indicates that water is the dominant gas source. The outgassing causes the composite spacecraft to charge up to a negative potential of up to −50 V. The distribution and intensity of the lower energy signal depends on the intensity of low energy electron fluxes around the spacecraft which again depend on the magnetic field orientation. We interpret the observation as being caused by water outgassing from different source locations on the spacecraft being ionized in two different regions of the surrounding potential. The interpretation is confirmed by two dimensional particle‐in‐cell simulations.

DOI： 10.1029/2023ja032044

Open Access

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.26464/epp2024003

Open Access

掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union (AGU)  

Abstract

Characterization, understanding, and prediction of the Martian radio environment are of increasing importance to the forthcoming human exploration of Mars. Here we investigate 3–5 MHz radio absorption in the nightside ionosphere of Mars caused by enhanced ionization at &lt;100 km altitudes during solar energetic particle (SEP) events. We conduct a quantitative analysis of radio absorption and SEP flux data that have been accumulated by two spacecraft currently orbiting Mars, thereby demonstrating that radio absorption is clearly correlated with SEP fluxes. A comparison of the observations with radio absorption properties predicted by a numerical model indicates that the relative temporal changes, radio frequency dependence, and SEP energy dependence of the observed radio absorption are in agreement with the model prediction. Meanwhile, the model systematically overestimates the radio absorption in the ionosphere by a factor of 3.7. We explore several sources of uncertainty, including the electron‐neutral collision frequency, absolute sensitivity of the SEP instrument, and limited transport of SEPs to the atmosphere, but the ultimate cause of the systematic discrepancy between the measured and modeled radio absorption is yet to be identified. Further efforts should be put into the development of a comprehensive and observationally validated model of radio absorption in the Martian ionosphere to assist the future crew and spacecraft activities on the surface of Mars.

DOI： 10.1029/2023sw003755

Open Access

記述言語：英語   掲載種別：研究論文（学術雑誌）  

<jats:title>Abstract</jats:title><jats:p>Mars lacks a global magnetic field, and instead possesses small-scale crustal magnetic fields, making its magnetic environment fundamentally different from intrinsic magnetospheres like those of Earth or Saturn. Here we report the discovery of magnetospheric ion drift patterns, typical of intrinsic magnetospheres, at Mars using measurements from Mars Atmosphere and Volatile EvolutioN mission. Specifically, we observe wedge-like dispersion structures of hydrogen ions exhibiting butterfly-shaped distributions (pitch angle peaks at 22.5°−45° and 135°−157.5°) within the Martian crustal fields, a feature previously observed only in planetary-scale intrinsic magnetospheres. These dispersed structures are the results of drift motions that fundamentally resemble those observed in intrinsic magnetospheres. Our findings indicate that the Martian magnetosphere embodies an intermediate case where both the unmagnetized and magnetized ion behaviors could be observed because of the wide range of strengths and spatial scales of the crustal magnetic fields around Mars.</jats:p>

DOI： 10.1038/s41467-023-42630-7

Open Access

記述言語：英語   掲載種別：研究論文（学術雑誌）  

<jats:title>Abstract</jats:title><jats:p>Lunar surface charging is a scientifically and practically important topic at the Moon that is largely determined by the electron currents near the surface. Among those electron populations, lunar photoelectrons (PHE) and backscattered electrons (BSE) produced by incident electrons that make up the high‐energy tail of lunar emitted electrons are not well characterized yet. Recently, Xu et al. (2021, <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://doi.org/10.1029/2020je006790">https://doi.org/10.1029/2020je006790</jats:ext-link>) reported oxygen Auger electron observations at the Moon by the Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun spacecraft, which provides a unique feature to identify lunar photoelectrons. We utilize this feature to isolate cases of emitted electrons dominated by BSE over PHE. With selected BSE cases, we characterize how the backscattering coefficient <jats:italic>η</jats:italic> varies with primary electron energy, which decreases with increasing energy. Our results also reveal <jats:italic>η</jats:italic> to be dependent on the magnetic dip angle, as a fraction of BSE re‐impact the surface in a magnetized environment. The characterization of the backscattering coefficient not only gives insights into the lunar surface properties and lunar surface charging but could also be potentially applied to other airless bodies.</jats:p>

DOI： 10.1029/2023je007983

Open Access

掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union (AGU)  

Abstract

Due to the lack of a dense atmosphere, the Moon directly interacts with ambient plasmas and solar radiation, leading to lunar surface charging. Solar X‐rays drive the emission of photoelectrons and Auger electrons from the lunar surface to space. The Auger electrons have characteristic energies intrinsic to the photo‐emitting atoms and were recently identified at the Moon by Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon’s Interaction with the Sun (ARTEMIS) observations. In this study, we developed a numerical model of the energy spectrum of lunar photoelectrons and Auger electrons, thereby comparing the predicted and observed energy spectra. By adjusting a scaling factor, the model well reproduces the ARTEMIS observations obtained in the solar wind, where the energy spectra are minimally affected by surface charging. Meanwhile, the energy spectra obtained in the geomagnetic tail can be significantly altered by lunar surface potentials. We show that it is difficult to determine a unique combination of the scaling factor and the lunar surface potential with the ARTEMIS energy resolution because of a strong parameter degeneracy. Nevertheless, for a fixed scaling factor, a strong correlation is identified between the lunar surface potentials inferred from the shifts of the energy spectra and those from the upward photoelectron beam energies, providing a proof of concept for the use of the photo‐emitted electrons as a new remote sensing tool of the lunar surface potential. We advocate for future observations of lunar electrons with a high energy resolution.

This article is protected by copyright. All rights reserved.

DOI： 10.1029/2023ja031707

Open Access

記述言語：英語   掲載種別：研究論文（学術雑誌）  

<jats:title>Abstract</jats:title><jats:p>The near lunar surface contains small‐scale magnetic field structures that provide a natural test bed for observing plasmas with a non‐zero Hall electric field, as well as potentially facilitating electron‐only reconnection. This study presents observational evidence of magnetized electrons as well as demagnetized ions when THEMIS‐ARTEMIS probe B reached an altitude of ∼15 km above the lunar surface. Additionally, observations suggest the presence of a field line topology change and traversal of a closed magnetic field structure containing solar wind electrons, suggestive of magnetic reconnection having occurred at some point between the solar wind interplanetary magnetic field and a lunar crustal magnetic field. Thus, the observations presented here are consistent with previous studies that predict prominent Hall electric fields near lunar crustal magnetic fields and further suggest that the solar wind interplanetary magnetic field may reconnect with lunar crustal magnetic fields, most likely via electron‐only reconnection.</jats:p>

DOI： 10.1029/2023gl104733

Open Access

掲載種別：研究論文（学術雑誌）   出版者・発行元：American Astronomical Society  

DOI： 10.3847/25c2cfeb.ed6f0be4

掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

Abstract

Mercury’s magnetosphere is known to involve fundamental processes releasing particles and energy like at Earth due to the solar wind interaction. The resulting cycle is however much faster and involves acceleration, transport, loss, and recycling of plasma. Direct experimental evidence for the roles of electrons during this cycle is however missing. Here we show that in-situ plasma observations obtained during BepiColombo’s first Mercury flyby reveal a compressed magnetosphere hosts of quasi-periodic fluctuations, including the original observation of dynamic phenomena in the post-midnight, southern magnetosphere. The energy-time dispersed electron enhancements support the occurrence of substorm-related, multiple, impulsive injections of electrons that ultimately precipitate onto its surface and induce X-ray fluorescence. These observations reveal that electron injections and subsequent energy-dependent drift now observed throughout Solar System is a universal mechanism that generates aurorae despite the differences in structure and dynamics of the planetary magnetospheres.

DOI： 10.1038/s41467-023-39565-4

Open Access

その他リンク： https://www.nature.com/articles/s41467-023-39565-4

記述言語：英語   掲載種別：研究論文（学術雑誌）  

<jats:title>Abstract</jats:title><jats:p>Chorus waves are naturally occurring electromagnetic emissions in space and are known to produce highly energetic electrons in the hazardous radiation belt. The characteristic feature of chorus is its fast frequency chirping, whose mechanism remains a long-standing problem. While many theories agree on its nonlinear nature, they differ on whether or how the background magnetic field inhomogeneity plays a key role. Here, using observations of chorus at Mars and Earth, we report direct evidence showing that the chorus chirping rate is consistently related to the background magnetic field inhomogeneity, despite orders of magnitude difference in a key parameter quantifying the inhomogeneity at the two planets. Our results show an extreme test of a recently proposed chorus generation model and confirm the connection between the chirping rate and magnetic field inhomogeneity, opening the door to controlled plasma wave excitation in the laboratory and space.</jats:p>

DOI： 10.1038/s41467-023-38776-z

Open Access

記述言語：英語   掲載種別：研究論文（学術雑誌）  

<jats:title>Abstract</jats:title><jats:p>The Martian crustal magnetic anomalies present a varied, asymmetric obstacle to the imposing draped interplanetary magnetic field (IMF) and solar wind plasma. Magnetic reconnection, a ubiquitous plasma phenomenon responsible for transferring energy and changing magnetic field topology, has been observed throughout the Martian magnetosphere. More specifically, reconnection can occur as a result of the interaction between crustal fields and the IMF, however, the global implications and changes to the overall magnetospheric structure of Mars have yet to be fully understood. Here, we present an analysis to determine these global implications by investigating external conditions that favor reconnection with the underlying crustal anomalies at Mars. To do so, we plot a map of the crustal anomalies' strength and orientation compiled from magnetic field data collected throughout the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. Then, we create “shear maps” which calculate and plot the angle of shear between the crustal fields and a chosen external field orientation. From there we define a “shear index” to quantify the susceptibility of a region to undergo reconnection based on a given overlaid, external field orientation and the resulting shear map for that region. We demonstrate that the shear analysis technique augments analysis of local reconnection events and suggests southward IMF conditions should favor dayside magnetic reconnection on a more global scale at Mars.</jats:p>

DOI： 10.1029/2022ja030989

Open Access

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

Abstract

The second Venus flyby of the BepiColombo mission offer a unique opportunity to make a complete tour of one of the few gas-dynamics dominated interaction regions between the supersonic solar wind and a Solar System object. The spacecraft pass through the full Venusian magnetosheath following the plasma streamlines, and cross the subsolar stagnation region during very stable solar wind conditions as observed upstream by the neighboring Solar Orbiter mission. These rare multipoint synergistic observations and stable conditions experimentally confirm what was previously predicted for the barely-explored stagnation region close to solar minimum. Here, we show that this region has a large extend, up to an altitude of 1900 km, and the estimated low energy transfer near the subsolar point confirm that the atmosphere of Venus, despite being non-magnetized and less conductive due to lower ultraviolet flux at solar minimum, is capable of withstanding the solar wind under low dynamic pressure.

DOI： 10.1038/s41467-022-35061-3

Open Access

その他リンク： https://www.nature.com/articles/s41467-022-35061-3

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media {LLC}  

<jats:title>Abstract</jats:title><jats:p>Wave–particle interactions are fundamental processes in space plasma, and some plasma waves, including electrostatic solitary waves (ESWs), are recognised as broadband noises (BBNs) in the electric field spectral data. Spacecraft observations in recent decades have detected BBNs around the Moon, but the generation mechanism of the BBNs is not fully understood. Here, we study a wake boundary traversal with BBNs observed by Kaguya, which includes an ESW event previously reported by Hashimoto et al. Geophys Res Lett 37:L19204 <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" xlink:href="https://doi.org/10.1029/2010GL044529">10.1029/2010GL044529</jats:ext-link> (2010). Focusing on the relation between BBNs and electron pitch-angle distribution functions, we show that upward electron beams from the nightside lunar surface are effective for the generation of BBNs, in contrast to the original interpretation by Hashimoto et al. Geophys Res Lett 37:L19204 <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" xlink:href="https://doi.org/10.1029/2010GL044529">10.1029/2010GL044529</jats:ext-link> (2010) that high-energy electrons accelerated by strong ambipolar electric fields excite ESWs in the region far from the Moon. When the BBNs were observed by the Kaguya spacecraft in the wake boundary, the spacecraft’s location was magnetically connected to the nightside lunar surface, and bi-streaming electron distributions of downward-going solar wind strahl component and upward-going field-aligned beams (at <jats:inline-formula><jats:alternatives><jats:tex-math>$$\sim$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:mo>∼</mml:mo>
</mml:math></jats:alternatives></jats:inline-formula>124 eV) were detected. The interplanetary magnetic field was dominated by a positive <jats:inline-formula><jats:alternatives><jats:tex-math>$$B_Z$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:msub>
<mml:mi>B</mml:mi>
<mml:mi>Z</mml:mi>
</mml:msub>
</mml:math></jats:alternatives></jats:inline-formula> (i.e. the northward component), and strahl electrons travelled in the antiparallel direction to the interplanetary magnetic field (i.e. southward), which enabled the strahl electrons to precipitate onto the nightside lunar surface directly. The incident solar wind electrons cause negative charging of the nightside lunar surface, which generates downward electric fields that accelerate electrons from the nightside surface toward higher altitudes along the magnetic field. The bidirectional electron distribution is not a sufficient condition for the BBN generation, and the distribution of upward electron beams seems to be correlated with the BBNs. Ambipolar electric fields in the wake boundary should also contribute to the electron acceleration toward higher altitudes and further intrusion of the solar wind ions into the deeper wake. We suggest that solar wind ion intrusion into the wake boundary is also an important factor that controls the BBN generation by facilitating the influx of solar wind electrons there.</jats:p>
<jats:p><jats:bold>Graphical Abstract</jats:bold></jats:p>

DOI： 10.1186/s40623-021-01566-2

Open Access

その他リンク： https://link.springer.com/article/10.1186/s40623-021-01566-2/fulltext.html

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media {LLC}  

<jats:title>Abstract</jats:title><jats:p>Japan Aerospace Exploration Agency (JAXA) plans a Phobos sample return mission (MMX: Martian Moons eXploration). In this study, we review the related works on the past climate of Mars, its evolution, and the present climate and weather to describe the scientific goals and strategies of the MMX mission regarding the evolution of the Martian surface environment. The MMX spacecraft will retrieve and return a sample of Phobos regolith back to Earth in 2029. Mars ejecta are expected to be accumulated on the surface of Phobos without being much shocked. Samples from Phobos probably contain all types of Martian rock from sedimentary to igneous covering all geological eras if ejecta from Mars could be accumulated on the Phobos surface. Therefore, the history of the surface environment of Mars can be restored by analyzing the returned samples. Remote sensing of the Martian atmosphere and monitoring ions escaping to space while the spacecraft is orbiting Mars in the equatorial orbit are also planned. The camera with multi-wavelength filters and the infrared spectrometer onboard the spacecraft can monitor rapid transport processes of water vapor, dust, ice clouds, and other species, which could not be traced by the previous satellites on the sun-synchronous polar orbit. Such time-resolved pictures of the atmospheric phenomena should be an important clue to understand both the processes of water exchange between the surface/underground reservoirs and the atmosphere and the drivers of efficient material transport to the upper atmosphere. The mass spectrometer with unprecedented mass resolution can observe ions escaping to space and monitor the atmospheric escape which has made the past Mars to evolve towards the cold and dry surface environment we know today. Together with the above two instruments, it can potentially reveal what kinds of atmospheric events can transport tracers (e.g., H<jats:sub>2</jats:sub>O) upward and enhance the atmospheric escape.</jats:p>
<jats:p><jats:bold>Graphical Abstract</jats:bold></jats:p>

DOI： 10.1186/s40623-021-01417-0

Open Access

その他リンク： https://link.springer.com/article/10.1186/s40623-021-01417-0/fulltext.html

記述言語：英語   掲載種別：研究論文（学術雑誌）  

<jats:title>Abstract</jats:title><jats:p>The lunar exosphere is an ensemble of multiple overlapping, noninteracting neutral distributions that reflect the primary physical processes acting on the lunar surface. While previous observations have detected and constrained the behavior of some species, many others have only circumstantial evidence or theoretical modeling suggesting their presence. Many species are so tenuous as to be unobservable by direct neutral sampling, yet in comparison, measurements in their ionized form provide a particularly sensitive method of detection. To better aid the interpretation of past measurements and planning of future observations, we present a model for the production of lunar pickup ions from the Moon consisting of two components: An analytic model for the distributions of 18 neutral species produced by various mechanisms and an analytic model for the ionization and subsequent acceleration of 20 exospheric and surface‐sputtered pickup ion species. The dominant lunar pickup ions in the model are <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/jgre22006-math-0001.png" xlink:title="urn:x-wiley:21699097:media:jgre22006:jgre22006-math-0001" />, He<jats:sup>+</jats:sup>, CO<jats:sup>+</jats:sup>, <jats:sup>40</jats:sup>Ar<jats:sup>+</jats:sup>, Al<jats:sup>+</jats:sup>, Na<jats:sup>+</jats:sup>, K<jats:sup>+</jats:sup>, Si<jats:sup>+</jats:sup>, Ca<jats:sup>+</jats:sup>, and O<jats:sup>+</jats:sup> with an asymmetric distribution favoring the positive interplanetary electric field hemisphere of the Moon. We compare the model predictions to statistically averaged pickup ion fluxes around the Moon as observed by the ARTEMIS spacecraft over the past decade. By filtering for interplanetary electric field‐aligned, high‐energy observations, we find that the pickup ion model lacks an additional source of heavy species. We suggest that a dense CO<jats:sub>2</jats:sub> exosphere of 3 × 10<jats:sup>4</jats:sup> − 1 × 10<jats:sup>5</jats:sup> cm<jats:sup>−3</jats:sup> could account for the missing pickup ion flux as part of the recycling of solar wind carbon ions incident to the Moon.</jats:p>

DOI： 10.1029/2022je007422

Open Access

掲載種別：研究論文（学術雑誌）  

DOI： 10.1029/2022GL100279

Open Access

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier {BV}  

DOI： 10.1016/j.pss.2022.105499

記述言語：英語   掲載種別：研究論文（学術雑誌）  

<jats:title>Abstract</jats:title><jats:p>We conduct a search for 5–16 Hz magnetic waves below 200 km and within the Martian ionosphere using data from multiple instruments onboard the Mars Atmosphere and Volatile EvolutioN mission spacecraft. We present a case study and an analysis of the 54 identified events to establish trends. Nearly half the wave events occur near the cusps of strong crustal magnetic fields (CMFs). The stronger regions have fewer events and may be a result of stronger CMFs preventing draped field lines from reaching lower altitudes. A majority of the observed magnetic waves occur on the nightside, are associated with greater fluxes of electrons traveling downward along the local magnetic field compared to those traveling upward, and correspond to increases in thermal plasma density. These aspects indicate electron precipitation was present during these wave events. We conclude that the waves are observed under magnetic field conditions favorable for the penetration of electrons and waves into the lower ionosphere, but that the electron precipitation cannot solely account for the waves or plasma changes.</jats:p>

DOI： 10.1029/2022ja030470

Open Access

記述言語：英語   掲載種別：研究論文（学術雑誌）  

<jats:title>Abstract</jats:title><jats:p>We present statistical analyses of whistler‐mode waves observed by Acceleration, Reconnection, and Turbulence and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS). Although some observations showed that the lunar whistler‐mode waves have similarities to the terrestrial chorus emissions, it remains unknown whether the banded structure typically seen in chorus is common to the lunar waves. In this study, we automatically detected whistler‐mode waves from 9 years of ARTEMIS data and classified them into four types of spectral shapes: lower band only, upper band only, banded, and no‐gap. We first show that a magnetic connection to the lunar surface is a dominant factor in the wave generation. The occurrence rate of whistler‐mode waves is 10 times larger on the magnetic field line connected to the Moon. Then we compared the field line connected events according to the position of the Moon and the condition of the field‐line foot point (day/night and existence of magnetic anomalies). The results show that (a) almost no banded event is observed in any circumstances, suggesting that generation mechanisms for the two band structure of the terrestrial chorus are largely ineffective around the Moon and (b) the wave occurrence rate depends on the foot point conditions, presumably affected by electrostatic/magnetic reflections deforming the velocity distribution of the resonant electrons. Thus, our results provide implications for the two band structure formation and new insights into fundamental processes of the Moon‐plasma interaction.</jats:p>

DOI： 10.1029/2022ja030582

Open Access

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union ({AGU})  

DOI： 10.1029/2022gl098007

Open Access

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media {LLC}  

<jats:title>Abstract</jats:title><jats:p>The Moon and Mercury are airless bodies, thus they are directly exposed to the ambient plasma (ions and electrons), to photons mostly from the Sun from infrared range all the way to X-rays, and to meteoroid fluxes. Direct exposure to these exogenic sources has important consequences for the formation and evolution of planetary surfaces, including altering their chemical makeup and optical properties, and generating neutral gas exosphere. The formation of a thin atmosphere, more specifically a surface bound exosphere, the relevant physical processes for the particle release, particle loss, and the drivers behind these processes are discussed in this review.</jats:p>

DOI： 10.1007/s11214-022-00875-6

Open Access

その他リンク： https://link.springer.com/article/10.1007/s11214-022-00875-6/fulltext.html

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union ({AGU})  

DOI： 10.1029/2021ja029867

Open Access

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media {LLC}  

<jats:title>Abstract</jats:title><jats:p>The mass spectrum analyzer (MSA) will perform in situ observations of ions and magnetic fields around Phobos as part of the Martian Moons eXploration (MMX) mission to investigate the origin of the Martian moons and physical processes in the Martian environment. MSA consists of an ion energy mass spectrometer and two magnetometers which will measure velocity distribution functions and mass/charge distributions of low-energy ions and magnetic field vectors, respectively. For the MMX scientific objectives, MSA will observe solar wind ions, those scattered at the Phobos surface, water-related ions generated in the predicted Martian gas torus, secondary ions sputtered from Phobos, and escaping ions from the Martian atmosphere, while monitoring the surrounding magnetic field. MSA will be developed from previous instruments for space plasma missions such as Kaguya, Arase, and BepiColombo/Mio to contribute to the MMX scientific objectives.</jats:p>

DOI： 10.1186/s40623-021-01452-x

Open Access

その他リンク： https://link.springer.com/article/10.1186/s40623-021-01452-x/fulltext.html

掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union (AGU)  

DOI： 10.1029/2021gl095260

Open Access

その他リンク： https://onlinelibrary.wiley.com/doi/full-xml/10.1029/2021GL095260

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union ({AGU})  

DOI： 10.1029/2021gl094585

Open Access

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media {LLC}  

DOI： 10.1007/s11214-021-00839-2

その他リンク： https://link.springer.com/article/10.1007/s11214-021-00839-2/fulltext.html

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union ({AGU})  

DOI： 10.1029/2020je006790

Open Access

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union ({AGU})  

DOI： 10.1029/2020gl091100

Open Access

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union ({AGU})  

DOI： 10.1029/2020ja028576

Open Access

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union ({AGU})  

DOI： 10.1029/2020ja028221

Open Access

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union ({AGU})  

DOI： 10.1029/2020ja028154

Open Access

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.icarus.2019.113392

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union (AGU)  

DOI： 10.1029/2019ja027312

Open Access

その他リンク： https://onlinelibrary.wiley.com/doi/full-xml/10.1029/2019JA027312

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union (AGU)  

DOI： 10.1029/2019ja026536

Open Access

その他リンク： https://onlinelibrary.wiley.com/doi/full-xml/10.1029/2019JA026536

掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

DOI： 10.1007/s11214-018-0576-4

Open Access

その他リンク： http://link.springer.com/content/pdf/10.1007/s11214-018-0576-4.pdf

掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union ({AGU})  

DOI： 10.1029/2018gl079282

Open Access

掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union ({AGU})  

DOI： 10.1029/2018gl079936

Open Access

掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union ({AGU})  

DOI： 10.1029/2018gl080136

Open Access

掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union ({AGU})  

DOI： 10.1029/2018ja025569

Open Access

掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier {BV}  

DOI： 10.1016/j.icarus.2018.05.030

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Blackwell Publishing Ltd  

DOI： 10.1002/2018GL077281

Scopus

掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union ({AGU})  

DOI： 10.1029/2017ja024618

Open Access

掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union ({AGU})  

DOI： 10.1029/2017ja024798

Open Access

Scopus

掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union ({AGU})  

DOI： 10.1029/2018ja025208

Open Access

掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union ({AGU})  

DOI： 10.1029/2017ja024729

Open Access

掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union ({AGU})  

DOI： 10.1029/2018gl077251

Open Access

掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union ({AGU})  

DOI： 10.1002/2018gl077622

掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union ({AGU})  

DOI： 10.1002/2017ja024913

掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union ({AGU})  

DOI： 10.1002/2017ja024772

掲載種別：研究論文（学術雑誌）   出版者・発行元：American Geophysical Union ({AGU})  

DOI： 10.1002/2017gl075831

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2017GL074897

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.icarus.2017.04.005

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2017GL073754

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2017GL073419

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2017JA023952

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2016JA023488

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2016JA023300

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2016JA023456

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2016JA023347

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2016JA023348

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2016JA023167

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2016JA023194

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2016GL068960

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2016GL068926

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2015JA022306

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2015GL067040

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2016GL067752

Web of Science

出版者・発行元：John Wiley {\&} Sons, Inc  

DOI： 10.1002/9781119055006.ch18

記述言語：英語   出版者・発行元：SpringerOpen  

DOI： 10.1186/s40562-015-0027-y

Open Access

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1126/science.aad0459

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2015GL064693

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2015GL065005

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2015GL065248

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2015GL065004

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2015GL065720

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1126/science.aad0210

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2015GL064781

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2015GL065293

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2015GL065346

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2015GL065304

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2015JA021211

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.icarus.2014.12.007

Web of Science

出版者・発行元：Springer Japan  

DOI： 10.1007/978-4-431-55084-6

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2014JA020618

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Blackwell Publishing Ltd  

DOI： 10.1002/2013JA019682

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/grl.50662

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Blackwell Publishing Ltd  

DOI： 10.1002/jgra.50296

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Blackwell Publishing Ltd  

DOI： 10.1029/2012JA017642

Open Access

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1029/2010GL044574

Open Access

Web of Science

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