Charged particles constitute one of the essential physical elements within the lunar space environment. Their origins, compositions and energy spectra are remarkably complex, and their spatial distribution and temporal dynamics are intricately coupled with localized electromagnetic field structures, rendering the lunar space environment fundamentally distinct from that of Earth or other magnetized planetary bodies. Compared to Earth, our methods for probing the lunar space environment remain relatively limited, both in terms of observational techniques and detection frequency. Notably, in situ measurements within the critical region encompassing the lunar surface and the low-altitude zone below 20 kilometers are exceptionally sparse. These observational gaps have collectively led to a fragmented and incomplete understanding of the fundamental characteristics of lunar charged particles, including their genesis, density fluctuations, dynamic behavior, as well as their potential spatial effects and associated hazards for exploration infrastructure and human activity. This review aims to synthesize and systematically organize the research findings from observations of lunar charged particles dating back to the Apollo era, endeavoring to present a coherent picture of the current state of knowledge and the trajectory of exploration. Recognizing that our comprehension of extraterrestrial space is profoundly shaped by the execution of national and international deep-space exploration programs, Section 1 begins by cataloging the key lunar missions undertaken by various nations, along with their primary scientific payloads and objectives. This historical overview is intended to illustrate the shifting priorities and evolving interests in lunar exploration over the decades. Given the inextricable coupling between charged particles and ambient electromagnetic fields, Section 2 provides a concise summary of the current understanding of lunar electromagnetic fields, encompassing both crustal magnetic anomalies and global fields, either transiently induced or permenantly intrinsic. The core of this review is structured along two parallel analytical threads. The first, covered in Sections 3 through 5, focuses on the "Background space environment along lunar orbit and its interactions with the Moon". This part examines the solar wind and geomagnetospheric plasma populations as they encounter and interact with the Moon, leading to phenomena such as absorption, reflection, and the formation of wake structures. The second thread, spanning Sections 6 to 11, is organized by "Types of charged particles in lunar space". Here, we systematically review observational results and theoretical models pertaining to specific particle populations, including photoelectrons, secondary electrons, exospheric neutrals, lunar dust, high-energy rays, and particles generated by human activities. Throughout this synthesis, it becomes evident that significant discrepancies and even outright contradictions exist, not only between theoretical predictions and observational data but also among different observational datasets themselves. These inconsistencies highlight the challenges inherent in remote and in situ space physics measurements and point to critical gaps in our current knowledge. Such uncertainties and unresolved questions likely define the most promising and necessary directions for future targeted investigations, requiring more advanced instrumentation, coordinated multi-point measurements, and sustained observation campaigns to unravel the complex electrodynamic environment of our closest celestial neighbor.

This study presents a climatological analysis of the systematic zonal differences in Equatorial Plasma Bubbles (EPBs) morphology, leveraging continuous observations from NASA's Global-scale Observations of the Limb and Disk (GOLD) mission between January 2023 and May 2025. Within the GOLD field of view, which continuously scans the nighttime ionosphere over the Americas and the Atlantic Ocean, a pronounced longitudinal asymmetry is uncovered: although backward C-shaped EPBs dominate overall, forward C-shaped EPBs occur more frequently in the western longitudinal sector than in the eastern sector. Statistical results demonstrate that this zonal morphological difference is a recurrent phenomenon, the occurrence of which follows the same seasonal pattern as the local EPB rates, being most frequent around equinoxes. Its occurrence rate increases with solar activity (F10.7 index) but shows no significant correlation with geomagnetic activity (Kp index). The magnetic longitudinal demarcation line between these morphological regions approximates a normal distribution, peaking around 25.9 degrees in magnetic longitude-a value notably close to the region of maximum magnetic declination. Analysis incorporating ionospheric zonal drift velocities from ROCSAT-1 data suggests that this morphological dichotomy originates from longitudinal variations in the latitudinal distribution of the plasma zonal drift, which is itself governed by the geomagnetic configuration. These findings provide robust, long-term observational evidence for the control of large-scale geomagnetic field geometry on the morphology of ionospheric plasma depletion.

A fundamental yet still poorly understood question in solar wind–magnetosphere interaction is how energy from solar wind is transferred into Earth's magnetosphere and subsequently transferred across scales. Utilizing high-resolution joint measurements from NASA’s MMS and THEMIS missions, we reveal a new pathway for solar wind energy from its global-scale injection into Earth’s magnetosphere to its cross-scale cascade down to electron scales, predominantly mediated by cross-scale wave-particle and wave-wave interactions. Enhancements in solar wind dynamic pressure directly drive solar wind energy into Earth’s magnetosphere in the form of ultra-low frequency (ULF) waves and mirror-mode structures. Their coupling adiabatically modulates electron distributions, producing butterfly distributions to supply sufficient free energy for generating whistler-mode waves within ULF wave troughs. Concomitantly, the whistler-mode harmonics emerge from nonlinear wave couplings. Throughout, energy is also transferred from ions to electrons via mirror-mode structures. These findings advance our understanding of energy transfer chain during the interactions between solar wind and Earth’s magnetosphere.

Ion precipitation is a major driver of sputtering on Mars, yet its behavior under extreme solar wind conditions remains poorly characterized. Using MAVEN observations, we analyze 124 extreme solar wind events from 2014 to 2018 together with a unique disappearing solar wind (DSW) interval. Precipitating ions are separated into low-energy (30-650 eV) and high-energy (650-25,000 eV) populations. Both statistical and event-specific analyses reveal a pronounced energy dependence. Low-energy precipitation increases with solar wind dynamic pressure but exhibits a two-stage response: an approximately linear rise at lower pressures followed by a markedly slower growth once a threshold pressure is exceeded. Low-energy precipitation flux also rises modestly with magnetic field strength and more steadily with Alfv & eacute;n Mach number. In contrast, high-energy precipitation flux shows little correlation with upstream conditions, suggesting distinct sources or acceleration pathways during extreme events. The DSW case further demonstrates that a substantial decrease in dynamic pressure is accompanied by a pronounced reduction in low-energy precipitation flux, while high-energy precipitation flux remains comparatively unchanged. These results indicate that ion precipitation differs from responses reported under nominal solar wind conditions.

Atmospheric tides can be divided into migrating tides, which propagate westward with the apparent motion of the Sun, and nonmigrating tides, which deviate from this sun-synchronous propagation. Among the latter, the nonmigrating diurnal tide DE3 is a major component of variability in the mesosphere and lower thermosphere (MLT), yet its event-scale response to stratospheric sudden warmings remains less well constrained, especially in terms of daily resolved observational evidence and its connection to the background propagation environment. Here, we analyze DE3 variations during the 2003/2004 Northern Hemisphere winter sudden stratospheric warming (SSW) using the daily DE3 product derived from TIMED/SABER observations and Hough mode decomposition. Results show an overall suppression of DE3 following the onset of SSW: In the vicinity of the equator, the amplitude of DE3 remained at significantly low levels during the warming period, and the 90-108 km mean-amplitude at representative latitudes indicates a reduced post-SSW amplitude. The warming/nonwarming comparison reveals clear suppression of DE3 near the equator. The multiyear comparison further shows that the DE3 amplitude during the post-warming stage is significantly lower than that in the control years. Hough-mode projections indicate that DE3 is mainly contributed by the low-order modes, with the leading symmetric (3,3) mode showing selective and delayed suppression. These features are consistent with a possible dynamical pathway in which SSW-related changes in low-latitude zonal-mean zonal wind and its meridional shear modify the equatorial propagation environment, which may contribute to the weakening of the equatorially concentrated leading symmetric (3,3) mode and the overall suppression of DE3.

It is still poorly understood at present how magnetic reconnection—a universal process in space, laboratory, and astrophysical plasmas—is triggered and developed, because there was no efficient technique to analyze such a super-dynamic and three-dimensional process. Even with the launch of NASA's MMS mission, studies of this process were still based on in-situ measurements along spacecraft trajectories and qualitative comparison with a schematic, which is stationary, two-dimensional, and oversimplified. As a result, using such conventional methodologies, the fundamental physics andinherent nature of magnetic reconnection cannot be uncovered. Here we invent a three-dimensional CT imaging technique, analogous to that in the hospital, and apply it to a magnetic reconnection in space. With the help of such an advanced technique, we at least made three exciting discoveries: (1) magnetic reconnection is triggered by whistler waves and developed by Hall effects; (2) magnetic reconnection accelerates electrons and converts energy via parallel electric fields; (3) magnetic reconnection converts magnetic energy to particle energy in the inflow region but inversely converts particle energy to magnetic energy near the X point, with the net conversion being (Binflow2-Boutflow2)/2m0during the whole process. These discoveries have upended the conventional concept and completely unraveled the fundamental nature of magnetic reconnection.

Plasma jets are important carriers of mass and magnetic flux and are favorable regions for development of various waves and instabilities in Earth’s magnetotail. Here we conduct a comprehensive investigation of electron temperature anisotropy constraints from electron microinstabilities inside magnetotail jets. We find that data distributions (temperature anisotropy vs. electron parallel beta) are well constrained by electron microinstability thresholds, with stronger magnetic fluctuations near the instability thresholds, providing direct evidence for the operation of microinstability instabilities. We reveal that the jets’ leading and inner regions typically host stronger magnetic fluctuations than their trailing regions, indicating that the microinstabilities are typically developed in association with jets’ interaction with ambient plasma. We find that instability-related magnetic fluctuations generally become weaker during the jets’ Earthward propagation, indicating gradual relaxation of the jets’ free energy. These results suggest that electron microinstabilities play an important role in controlling electron thermodynamics in plasma jets.

Nitric oxide (NO), a minor constituent of the Earth's lower thermosphere, emits 5.3-mu m infrared radiation, causing an important cooling effect on the thermosphere. In this study, the eclipse-induced NO cooling changes are investigated using the SABER and GOLD measurements and the Thermosphere-Ionosphere modeling of the 14 October 2023 eclipse. The observations show a NO cooling depletion (similar to 4 erg/cm(3)/s, similar to 40%) in SABER measurements that is concurrent with a reduction in neutral temperature (similar to 60 K) in GOLD observations around 150 km altitude, associated with an increased O/N2 ratio. The Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM) captures the morphology of the eclipse-induced effects but underestimates the observed variations. The data-model comparison confirms this depletion caused by the decreased NO density and temperature. Model term analysis shows that the eclipse-induced decrease in NO density is mainly produced by the chemical process instead of dynamic transport. The temperature-dependent reaction rate of NO production from Duff et al. (2003, https://doi.org/10.1029/2002GL016720) was further tested and quantified the cooling depletion better. However, there still exists a discrepancy in neutral temperature changes. This study presents multi-source observations of eclipse-induced NO cooling changes, and contributes to the understanding of cooling processes in the thermosphere-ionosphere system.

The Kelvin–Helmholtz (KH) instability is a fundamental plasma process in many astrophysical environments; its vortices facilitate solar wind energy transport and plasma mixing. We investigate the energy flux density distribution and fluctuations of a typical KH vortex event observed by THEMIS across different magnetopause regions. Power spectral density (PSD) analysis of different energy flux densities reveal that their peaks correspond to the main period with a maximum of approximately 138 s for efficient energy transport. Satellite observations show that the spatial distributions of mass and energy vary markedly across different regions of magnetopause KH vortices. The region near the inner magnetopause is predominantly governed by electromagnetic energy flux density, whereas the area near the outer magnetopause is more significantly influenced by a combination of thermal and kinetic energy flux densities. Mass transport mainly occurred near the outer magnetopause, while plasma heating may have taken place in the outer magnetosphere. Furthermore, we estimate a local, per-unit-area energy transmission fraction across the magnetopause during the KH interval by time integrating the boundary-normal energy flux density. Using upstream OMNI data as a proxy for the incident solar wind energy flux, we infer that up to ∼ 2.19

Plume-induced dust transport is a major hazard during lunar landing, but the charging history of lofted grains is often simplified as a plasma-equilibrium problem. This assumption overlooks the rapid triboelectric charging produced by plume-driven dust collisions and its possible persistence after engine shutdown. This study develops a coupled multiphysics model for charged lunar dust transport under plume impingement during lunar landing. The model integrates plume-induced gas–solid interaction, triboelectric charging from dust collisions, shifted orbital-motion-limited plasma charging, and electrostatic dust transport. Verification against nozzle-exit measurements and published plume solutions confirms that the framework captures the main plume aerodynamics and provides a reliable basis for predicting dust motion. The results show that pre-shutdown dust ejection is mainly governed by aerodynamic forcing, whereas post-shutdown transport of fine grains is strongly affected by inherited triboelectric charge before the grains relax toward the plasma-controlled equilibrium state. This effect is highly size selective: it amplifies transport deviations mainly in the fine-grain regime rather than uniformly affecting all particles. Neglecting inherited triboelectric charge can lead to large prediction errors for submicrometer grains, with the divergence index reaching 144.6% for 0.1 μm particles. Under stronger electric fields, the sensitive range further extends toward 1 μm grains, whereas 100 μm grains remain nearly unaffected. Under the representative lunar plasma condition, the inherited triboelectric charge and plasma-equilibrium charge reach comparable magnitudes at a grain radius of approximately 2.27 μm, marking a charge-scale crossover rather than a transport threshold.

Field-aligned potential drop is an important phenomenon in the magnetosphere-ionosphere coupling system. Using the kinetic Storm-Time Ring Current Model (STRIM), which has fulfilled a self-consistent electric field calculation, we investigate the role of field-aligned potential drop in regulating the magnetosphere-ionosphere coupling by incorporating field-aligned potential drop into the model. It was found that field-aligned potential drop significantly reduces particles' pitch angle and increases their energies, equivalently broadening their bounce loss cone and enhancing magnetospheric particle precipitation. In regions where the potential drop reaches several kilovolts, the discrete precipitating electron flux driven directly by the potential drop becomes dominant over the diffuse precipitation, contributing over 90% to the total precipitation. The associated average energy is also enhanced by up to similar to 60%, compared to cases without a strong field-aligned potential drop. The ionospheric conductivity of the regions with discrete electron precipitation was further evaluated by the GLOW model. It is found that Pedersen and Hall conductance in the E region (similar to 150 km in height) are almost entirely controlled by discrete precipitation if the field-aligned potential drop is over 10 kilovolts. These results provide quantitative evidence that field-aligned potential drop strongly modulates the intensity and energy spectrum of precipitating particles and substantially influences the ionospheric electrodynamics.

The Scale-Invariant Feature Transform (SIFT) algorithm detects key points and generates descriptors in images, enabling features matching across different images for object recognition and tracking. We derived the zonal drift velocities of equatorial plasma bubbles (EPBs) by tracking SIFT key points in GOLD Nmax data. Zonal drift velocities varied from similar to 40 m/s to similar to 160 m/s and exhibited prominent seasonal variations: the average drift velocity for different longitudes peaks around the Northern Hemisphere's winter solstice month and reaches its minimum near the summer solstice month. The results show that the zonal drift speeds of EPBs are larger during high solar activity, while intense geomagnetic activity suppresses eastward drift velocities. This study represents the first application of the SIFT algorithm to satellite airglow images. Our findings reveal climatological variations in ionospheric zonal drifts, providing new observational foundations for advancing the understanding of ionospheric electrodynamic processes.

Based on Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED)/Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) temperature observations and the Real-Time Multivariate Madden-Julian Oscillation (MJO) Index, this study provides the first analysis of the non-migrating SE2 temperature tide at daily resolution and its response to the MJO phenomenon across phases 1-8 between +/- 45 degrees latitude from 2003 to 2012, in the Mesosphere and Lower Thermosphere (MLT) region. The main findings are as follows: (a) The SE2 tide exhibits pronounced variations with MJO phase across all seasons above 100 km altitude, accompanied by clear phase shifts under different MJO conditions. (b) The SE2 response to the MJO is more evident during solstices than during equinoxes, with the more evident modulation occurring in the June solstice. (c) The asymmetric component of the SE2 response dominates over the symmetric component throughout the seasons. In summary, the daily resolved SE2 tide, particularly its phase behavior, plays a key role in shaping the seasonal characteristics and symmetric patterns in the MLT region under MJO forcing.

Chorus emissions, among the strongest electromagnetic waves occurring in nature, have been believed to cause intense electron acceleration which can significantly alter space weather and climate. However, direct measurement of electron acceleration by chorus has been highly challenging due to small spatiotemporal scales involved. Here we present ultrafast measurements of electron acceleration by space chorus, using high-cadence observations from NASA’s Magnetospheric Multiscale spacecraft. We find that the observed chorus is associated with locally-accelerated energetic electrons exhibiting butterfly pitch angle distribution, and the chorus waves were locally damping, resulting in energy gain of electrons mainly at direction perpendicular to ambient magnetic field by cyclotron resonance. We demonstrate that the chorus-driven electron acceleration was ultrafast, with a net acceleration ratio of approximately 300 eV/s, and reveal that the electron acceleration was established in association with nonlinear wave trapping, controlled by spatiotemporal inhomogeneity of wave frequency and magnetic field. These observations provide direct evidence for nonlinear, ultrafast electron acceleration by chorus, suggest that future space weather forecasting models should incorporate chorus-induced nonlinear effects, and offer important insights into understanding energetic radiations in geospace and beyond. Chorus waves are thought to cause strong electron acceleration altering space weather, yet its fundamental physics remain unclear. Here, the authors present observational evidence for highly nonlinear, ultrafast chorus-induced electron acceleration.

The physical properties of lunar regolith, such as particle size, complex refractive index, single scattering albedo (SSA), and scattering asymmetry parameter, are crucial for understanding space weathering processes on the Moon. Here, we apply an improved microphysical photometric model (M-XZL), which accounts for both shadow-hiding and coherent-backscatter opposition effects, to in situ reflectance observations from the Chang’E-3 (CE-3) panoramic camera. We extract these parameters and investigate the photometric characteristics of the surface regolith at the CE-3 landing site. The retrieved SSA value of approximately 0.7 is significantly higher than those reported in previous studies based on the Hapke model. This may suggest either a lower degree of space weathering at the site, or an overestimation of the absorptive effect of space weathering products (e.g., nanophase iron), or both. These findings may indicate a slower regolith maturation rate and provide improved constraints on models of lunar surface evolution.

Solar wind alpha particles exhibit preferential heating and acceleration relative to protons; however, their behavior in the vicinity of turbulent coherent structures remains less understood. We report the first evidence of localized alpha particle and proton heating within coherent structures identified using the Partial Variance of Increments (PVI) method, based on Parker Solar Probe (PSP) observations. Our results show that high-PVI events are associated with significant, species-dependent temperature enhancements: protons undergo a relative larger temperature increase than alpha particles. This preferential proton heating produces a localized decrease in the alpha-to-proton temperature ratio, indicating that the plasma is driven toward thermal equilibration between species. The heating is also anisotropic, being dominated by enhancements in the perpendicular temperature. These temperature-signatures coincide with a pronounced reduction in the normalized alpha-proton differential flow speed and a localized minimum in the Coulomb collision age, suggesting that the relaxation is affected primarily by collisionless kinetic effects. These findings provide new insight into the intermittent energy conversion and ion thermodynamics in the solar wind.

Resolving the mixture of natural plasma waves and persistent spacecraft interference is a fundamental challenge in space physics, as it obstructs the analysis of wave-particle interactions and energy transport processes. Traditional signal decomposition methods often fail to adequately separate these components due to their time-varying frequencies and overlapping spectra. We propose the instantaneous bandwidth Vold-Kalman Filtering (IB-VKF), which first defines the component-specific bandwidth weighting functions , allowing for the independent and precise dynamic tracking of disparate signal features. We demonstrate the algorithm's geophysical utility using data from the CASSIOPE/Swarm-Echo and CSES missions. The IB-VKF successfully isolates persistent reaction wheel interference with suppression ratios exceeding 22 dB, and, more critically, separates transient whistler waves from background platform noise, achieving suppression ratios of 9.34 dB for the natural waves. By significantly enhancing the fidelity of space magnetic data, the IB-VKF provides a powerful new tool for probing wave-particle coupling and magnetospheric dynamics. Plain Language Summary Resolving the mixture of natural plasma waves and persistent spacecraft interference is a key problem in space physics, because it obstructs the study of wave-particle interactions and energy transport processes. Traditional ways often can't separate these well enough this is because the waves and noise have frequencies that change over time and overlapping frequency ranges. To address this, we propose the instantaneous bandwidth Vold-Kalman Filter (IB-VKF). It allows for the independent and precise dynamic tracking of disparate signal features. Applying IB-VKF to magnetic field data from the CASSIOPE/Swarm-Echo and CSES missions, we show that it effectively removes strong spacecraft noise and successfully reveals transient whistler waves that were previously hidden. By making space magnetic field data much clearer, the IB-VKF offers a powerful new tool for studying wave-particle coupling and magnetospheric dynamics.

We conducted a statistical study on the orientation of field-aligned currents (FACs) sheets in the high latitude fields of the Northern Hemisphere (NH) and Southern Hemisphere (SH) under different seasonal conditions, interplanetary magnetic field (IMF), and geomagnetic activity. We use the maximum correlation method to analyze nearly 9 years of measurements from Swarm A and C satellites. The orientation of the FAC sheets during each aurora oval crossing and the corresponding angle between the FAC sheets and the aurora boundary are derived. We find that under all conditions, the dawnside FAC sheets are clockwise at the aurora boundary, while the duskside are counterclockwise, which is similar to the flow pattern of auroral electrojet currents (AEJs) (westward on dawnside, eastward on duskside), indicating that AEJs may limit the spatial arrangement of FAC sheets. IMF By will affect the dawn-dusk asymmetry of FAC sheets arrangement, and enhanced geomagnetic activity will cause FAC sheets in both hemispheres to develop towards a more regular arrangement direction. In addition, the hemisphere and seasonal differences in FAC sheets arrangement may be related to changes in ionospheric conductivity. Our findings provide important information for the dynamic modulation of the ionospheric current system driven by external forces. In the future, the combination with SMILE satellite data will help to improve the M-I coupling model.

Abstract The interplanetary magnetic field (IMF) is one of the important external drivers that control the Martian plasma environment. There is some controversy about the characteristics of the Martian plasma environment under radial IMF conditions. Utilizing a three‐dimensional magnetohydrodynamic (MHD) model, this study analyzes the impact of IMF cone angle on the electromagnetic field and ion motions in Martian space, and investigates the Martian space environment under radial IMF conditions. Simulation results indicate that the decrease in IMF cone angle weakens the electromagnetic fields. The reduction in magnetic field pile‐up leads to a weakened induced magnetosphere. Therefore, solar wind protons experience less deceleration and deflection across the bow shock (BS), which is compressed to lower altitudes. Under radial IMF, though the electric fields that impede the penetration of solar wind particles are weak on the dayside, the BS, the magnetosheath, and the induced magnetosphere structure can still form, and the pile‐up of magnetic fields can still be observed. In contrast to previous reports of BS disappearance under radial IMF, our simulations show that a BS and a structured magnetosheath persist even at extremely small cone angles. These results help reconcile conflicting observations and provide constraints for interpreting MAVEN measurements during near‐radial IMF intervals.

Understanding which processes control atmospheric escape and the loss of water from planetary environments is crucial. The ESA’s Venus Express spacecraft has observed a significant depletion in Venus’s upper atmosphere, driven by the solar wind. In such scenarios, the electromagnetic force can accelerate planetary ions to energies that allow them to escape from the planet. However, it is extremely challenging to directly measure electromagnetic forces on planetary ions. Here we present a 3D multifluid Hall–magnetohydrodynamics simulation model to investigate electromagnetic force terms and the effects of each term on solar wind plasma and planetary ions. We find that the total electromagnetic force reaches its peak near the bow shock and the magnetic pileup boundary, with obvious asymmetric characteristics, which slows down the solar wind plasma and compresses the heavy ions toward Venus. In addition, the morphology of the convection electric field force shows obvious north–south asymmetry, which leads to the formation of asymmetric structures and plasma flows in the Venusian magnetotail. The electromagnetic force patterns obtained by simulation are consistent with the results and speculation from observations, suggesting that the multifluid model developed here has substantial capacity in further analysis regarding planetary ion escape.