The Moon, unlike Earth, does not have a global dipolar magnetic field. Instead, there are localized patches of crustal magnetization scattered across its surface. The general morphology of crustal magnetic fields has been obtained from low-altitude measurements taken by the Lunar Prospector and Kaguya missions, and surface maps have been generated using both forward and inverse models based on these orbital data, although we are still far from a precise description. Strong crustal magnetic fields can deflect or reflect the solar wind away from the surface, while unprotected regions of the surface undergo a darkening and reddening process in visible to near-infrared wavelengths known as space weathering. Recent satellite observations and advanced numerical simulations, however, showed that the interaction between the solar wind and lunar crustal fields is surprisingly complex, and we still do not fully understand the exact mechanisms behind the solar wind-crustal fields interaction. In this study, we utilize a hybrid-kinetic plasma model, Amitis (https://www.amitiscode.com), to simulate the effects of the lunar crustal magnetic fields on the plasma environment of the Moon. We investigate the interaction between the solar wind and the lunar crustal fields and its dependence on the IMF orientation. We focus on the Reiner Gamma magnetic anomaly and on how the morphology of the crustal fields over it shields the surface from the incoming solar wind and contributes to surface weathering. We further examine the factors controlling surface shielding by strong crustal fields. We find that the lunar crustal fields can either partially or fully shield the surface in the vicinity of their location from solar wind protons depending, in addition to the strength of the magnetic field, on the angle of the incident solar wind.

How to cite: Stergiopoulou, K., Fatemi, S., and Waller, C. D.: Solar wind interaction with lunar crustal magnetic fields: The Reiner Gamma magnetic anomaly, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-130, https://doi.org/10.5194/epsc2026-130, 2026.

EPSC2026-130

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The establishment of long-term human presence on the Moon requires infrastructure capable of operating under persistent radiation exposure and extreme thermal conditions while minimising dependence on Earth-supplied materials. Radiation-induced degradation of construction materials poses a critical risk to the safety, durability, and sustainability of lunar habitats, particularly those based on in situ resource utilisation (ISRU). Understanding the degradation of lunar construction materials under combined radiation and thermal conditions is therefore essential for the development of sustainable lunar infrastructure.

This work investigates the response of ISRU-relevant materials to simulated lunar environmental conditions using a combined modelling and experimental approach. Ion irradiation experiments and thermal cycling studies are being conducted to reproduce key aspects of the lunar surface environment and to assess damage in materials including advanced polymers, metallic composites, aerogels, and lunar regolith analogues. Post-exposure characterisation using spectroscopy and microscopy is employed to evaluate chemical, structural, and mechanical degradation.

In parallel, atomistic and multi-scale modelling approaches are being developed to investigate thermally induced structural evolution in these materials. The modelling framework aims to connect microscale damage processes with macroscopic material degradation relevant to long-term lunar operations.

This research builds on previous atomistic studies of space materials under lunar-like conditions, extending them through experimental validation and the investigation of regolith-derived materials as both structural resources and passive radiation shielding elements. The results will contribute to improved material selection and mitigation strategies for future ISRU-based lunar habitats.

How to cite: Bhowmick, A., Souza, C. P., Fantuzzi, F., Mason, N., and Sulik, B.: Simulating Radiation and Thermal Cycling Effects in Lunar Construction Materials, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-615, https://doi.org/10.5194/epsc2026-615, 2026.

EPSC2026-615

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INTRODUCTION:

Lunar dust represents a critical challenge for sustainable lunar exploration, affecting astronaut health, equipment performance, and scientific instrumentation. The finest fraction of lunar regolith (<20 μm) exhibits unique electrostatic properties resulting from solar UV radiation and plasma bombardment, leading to charge-driven levitation and transport phenomena. Observations from Apollo missions, including the enigmatic "horizon glow" detected by Surveyor landers, suggest dust clouds extend tens of centimetres to kilometres above the lunar surface. Recent measurements by NASA's LADEE mission confirmed permanent low-density dust populations at altitudes up to 260 km.

Despite these observations, fundamental questions remain about dust detection methodologies, size-dependent scattering properties, and the feasibility of optical characterization techniques for future in-situ instrumentation. This study addresses these knowledge gaps through controlled laboratory experiments using lunar dust analogs and laser-optical backscattering measurements.

METHODOLOGY:

We constructed a laser-optical detection system comprising a pulsed laser (λ = 532 nm, repetition rate ~100 Hz) aligned with a high-resolution CMOS camera. Particles were released in free-fall through the laser beam at two controlled distances (approximately 1.0 m and 1.5 m from the optical system), providing sufficient observation time for detection and tracking. Experiments used two lunar analog materials spanning the size range relevant to electrostatically active lunar dust: silver-coated silica microspheres (nominal diameter ~10 μm) and copper powder (nominal diameter ~30 μm). These materials provide contrasting optical properties for backscattering validation across different refractive indices and compositions.

An automated Python-based analysis workflow using OpenCV and TrackPy libraries for particle detection, sizing, and trajectory tracking was developed. Image preprocessing included contrast enhancement, morphological operations for noise reduction, and adaptive thresholding for segmentation. Particle contours were extracted and characterized by equivalent circular diameter, eccentricity, and spatial coordinates. Validation against synthetic particle images confirmed >95% detection accuracy with minimal sizing error. Mie scattering theory provided theoretical predictions for backscattered photon counts as a function of particle size, wavelength, and complex refractive index, incorporating Gaussian beam propagation and spatially-varying irradiance profiles. Signal-to-noise ratio (SNR) estimates included contributions from dark noise, shot noise, and read noise measured from reference frames.

RESULTS:

The system successfully detected over 27,000 individual particles across all experimental conditions, demonstrating robust optical detection capabilities. Mean SNR exceeded 30, significantly above the threshold required for reliable sizing, with performance independent of material composition—silica and copper particles exhibited comparable signal quality despite contrasting refractive indices. This material independence is scientifically significant for future lunar applications, as it demonstrates the technique will work reliably across the diverse mineralogy of lunar regolith without recalibration.

Batch analysis revealed systematic electrostatic agglomeration affecting all samples, with severity inversely proportional to nominal particle size. Fine silica particles (~10 μm nominal) exhibited agglomeration factors reaching 40-50×, while coarser copper particles (~30 μm nominal) showed more modest clustering at approximately 8-10×. Size distributions exhibited strong right-skew with occasional extreme outliers, indicating hierarchical agglomeration processes characteristic of electrostatic clustering. This agglomeration reflects genuine electrostatic charging physics rather than measurement artifacts, as confirmed by reproducibility across thousands of independent particle detections. Reducing measurement distance by approximately 30% improved apparent size measurements by 70-75% for both materials, confirming how the detected aggregated brightness of the particle changes the size estimation. Analysis of pixel pitch versus particle size demonstrated that individual grain detection of 10 μm particles requires spatial resolution better than 5 μm/pixel, achievable only at shorter distances. The 30 μm copper particles approached optical resolvability at the closer distance, with agglomeration factors dropping to approximately 2×.

Comparison between experimental backscattered photon counts and Mie predictions revealed qualitative agreement with significant quantitative discrepancies. Correlation analyses confirmed size-dependent scattering trends with moderate-to-strong positive correlations (r ~ 0.5-0.7), demonstrating that the fundamental principle of optical backscattering for size discrimination is sound. However, measured photon counts systematically underestimated theoretical predictions by approximately an order of magnitude. This gap likely reflects following factors: irregular cluster morphology deviating from Mie's spherical assumptions, effective refractive index uncertainties for agglomerated structures with internal voids. Despite this quantitative mismatch, the qualitative validation confirms that larger particles consistently produce more detectable photons—the critical relationship enabling optical sizing.

Particle velocity measurements yielded highly consistent terminal velocities (~0.3 m/s with <5% variation), confirming gravity-dominated vertical trajectories with negligible air convection effects. This reproducibility validates the free-fall experimental approach and demonstrates that particle dynamics are predictable and suitable for controlled laboratory studies.

DISCUSSIONS AND CONCLUSIONS:

This study establishes proof-of-concept for laser-optical dust detection with several key findings relevant to future mission instrumentation. The system demonstrates material-independent detection across diverse mineral compositions, high SNR enabling confident particle discrimination, and successful validation of fundamental Mie scattering physics despite morphological complexities. The automated analysis pipeline is scalable to higher throughput and suitable for real-time processing on rover computers.

Three primary limitations were identified with clear mitigation pathways. First, severe electrostatic agglomeration prevents individual grain characterization without charge neutralization—addressable through ionized atmosphere particle injection or fully-enclosed vacuum chamber designs. Second, optical resolution constraints require either shorter measurement distances, or increased magnification. Third, quantitative Mie discrepancies necessitate empirical calibration with reference particles or advanced scattering models accounting for non-spherical geometries.

For mission applications, proposed rover-mounted instruments incorporating stereo camera configurations could enable 3D particle reconstruction, complete scattering phase function measurements, and real-time dust hazard assessment during surface operations. With identified technical improvements implemented, estimated instrument specifications (mass <5 kg, power <10 W, autonomous 100 Hz operation) are feasible for rover deployment. This work contributes foundational data for understanding dust scattering physics and establishes technical feasibility for future lunar surface dust monitoring systems supporting Artemis exploration objectives.

How to cite: Dabhi, K.: Laser-optical detection and characterization of suspended lunar dust analogs, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-1075, https://doi.org/10.5194/epsc2026-1075, 2026.

EPSC2026-1075

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The Moon is a unique and accessible target that hosts a distinctive space environment. It provides an opportunity to investigate fundamental physics associated with interactions with the undisturbed solar wind, magnetosheath, and magnetosphere. During disturbed space weather events, the lunar environment is influenced by hot plasma within the coronal mass ejections or high-energy particles such as solar energetic particles or cosmic rays. In the absence of an intrinsic magnetic field and a collisional atmosphere, the solar wind directly impacts the lunar surface, resulting in a plasma–regolith interaction, the physics of which remains poorly explored.

The interaction also sputters surface volatiles, producing the exosphere, a fragile gaseous environment surrounding the Moon. Space plasma may also contribute to the formation of surficial water, which can subsequently be released into the exosphere or space by meteoroid impacts. However, direct observational evidence for the production, circulation, and accumulation of such species remains highly limited. In addition, the Moon has localized magnetic anomalies that modify the incident plasma flow and, consequently, the near-surface environment. These disturbances are known as mini-magnetospheres, the smallest magnetospheres known. Local disturbances from environmental changes (electromagnetic fields, illumination, and their temporal variations) can induce significant dust lofting. Lunar dust poses a major hazard to human and robotic explorers. It is adhesive, potentially toxic, and easily mobilized. Dust particles can easily penetrate inside electronics systems and spacesuits, and are significantly influenced by near-surface electric and magnetic fields. Furthermore, since the beginning of the space age, the lunar environment has been increasingly altered by human activities. Planned or ongoing exploration is expected to accelerate this anthropogenic modification. Quantifying the lunar environment is therefore urgently required to distinguish between its (near-)pristine state and its altered conditions on a decadal time scale.

In this presentation, we provide an overview of the multidomain physical processes—both natural and anthropogenic— that occur at the lunar surface in the context of future lunar surface missions. We identify key open scientific questions concerning the lunar space environment and outline the measurements required to address them. These measurements are considered within the framework of the European scientific payload package concept, AstroLEAP (Lunar Environment Analysis Package), which is under study by ESA and the science community.

How to cite: Futaana, Y. and Dandouras, I. and the The AstroLEAP Phase A/B1 study team: Interdisciplinary exploration science enabled by lunar landers: AstroLEAP sciences, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-782, https://doi.org/10.5194/epsc2026-782, 2026.

EPSC2026-782

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During the Apollo missions, it has been well understood that the abrasive and adhesive nature of the lunar regolith was an impediment to the success of future robotic and manned missions. In recent years, many studies focus on understanding dust behaviour under a representative environment. VUV is used to mimic the side of the Moon that is illuminated by the sun, whereas electron irradiation is used to mimic the dark side of the Moon. One major topic that is currently addressed is the assessment of the electrical charge of the lunar regolith under VUV and electron irradiation. The main objective is to study its electrical properties and estimate its adhesion forces. On Earth, different simulants are used and compared to each other. Therefore, the adhesion forces are not only charge and environmental (topography, irradiation conditions, etc) dependent, but also simulant dependent. Studying a large range of dust simulants thus helps us to refine our understanding of the behaviour of the lunar regolith. This will help define and design mitigation techniques that will protect scientific instrument and, more generally, ensure the safety of future lunar missions.

For future lunar missions, it is important characterize the charge and size of dust particles to assess their adhesion forces. Measuring the particles’ charge and size allows us to derive whether the charge of dust particles depends on its size or if it is merely a consequence of the environment and local topography. These measurements will also allow us to compare the significance between the lunar regolith and the different dust simulants (JSC-1A, LHS-1, LMS-1, etc), making it easier to extrapolate the behaviour of the lunar regolith. Additionnally, refining our understanding of the electrical properties of the lunar regolith through experimental analysis will contribute to the improvement of simulating tools, such as SPIS ([1]), and allow us to anticipate future critical cases on the Moon.

Previous studies that have been led at ONERA with BIRA-IASB have shown that lunar dust simulant JSC-1A is charged negatively and positively under VUV irradiation [2]. This behaviour shows that emitted photoelectrons tend to differentially charge neighbouring grains. According to the patch charge model, deeper layers are charged negatively whereas layers at the surface are predominantly charged positively. In this study, it was shown that 50% of particles have a charge lower than +/- 10 fC. This is valuable information for the design of future mitigation techniques, as it gives a good overview of the electrostatic force that could be applied to extract dust particles from their substrate, or simply prevent them from adhering. Other simulants have also been tested but displayed quite different behaviour. LHS-1 has been tested under VUV and electron irradiation, but few dust grains were detected. This indicates that LHS-1 and JSC-1A have quite different electrical properties, that lead to very distinct behaviours under irradiation.

[1]          P. Oudayer et al., « Multiscale Modeling of Dust Charging in Simulated Lunar Environment Conditions », IEEE Trans. Plasma Sci., vol. 47, n^o 8, p. 3710‑3716, août 2019, doi: 10.1109/TPS.2019.2919932.

[2]          R. Pacaud, J.-C. Matéo-Vélez, S. Hess, et S. Ranvier, « Measurement of bipolar charge distribution of lunar dust simulant under VUV irradiation », Planetary and Space Science, vol. 263, p. 106120, sept. 2025, doi: 10.1016/j.pss.2025.106120.

How to cite: Pacaud, R. and Ranvier, S.: Laboratory measurement of the charge and adhesion forces of lunar regolith simulants, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-1122, https://doi.org/10.5194/epsc2026-1122, 2026.

EPSC2026-1122

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The Moon almost certainly hosted an internally generated dynamo in the past [1]. When the lunar crust was modified by impacts or magmatic processes in the presence of a dynamo field, portions of the crust acquired remanent magnetization, leading to pronounced magnetic anomalies (some reaching tens of nT at the surface) detectable from orbit [2–3]. Constraining the structure of magnetized sources that generate these observed magnetic anomalies is key to reconstructing the lunar magnetic history and understanding the thermal and magnetic evolution of its crust.

Assuming the lunar dynamo field was dominated by the dipolar component, and if the geographic locations and the magnetization direction of the source body are known, one can estimate the location of the paleopole at the time when remanent magnetization was acquired. However, paleopoles inferred from orbital data are widely scattered across the lunar surface, spanning all latitudes and longitudes [4]. This distribution may reflect either a time-variable and non-stationary dipole axis or a field that was not predominantly dipolar.

When estimating the magnetization and direction of the magnetizing field, earlier studies used various assumptions of the source geometries, including a single dipole [5,6], a set of unidirectional dipoles (e.g., Parker’s method) [7], and uniformly magnetized prisms [8]. However, these assumptions have not been systematically examined against observational constraints. If the ambient field varied significantly during magnetization (e.g., reversing dynamo field), magnetization intensity may be underestimated, and inaccurate paleofield directions may be retrieved [9].

A uniformly magnetized source of simple geometry that generates homogeneous magnetic fields can be approximated by a point source [10,11], the magnetic field of which follows a simple power law field fall-off function T=Cr^-N, where T is the magnetic anomaly, r is the distance, C is the coefficient as a function of direction associated with anomalous magnetization, and N is the scaling index that describe the delay of signal strength with distance. The constant intergal scaling index corresponds to sources of different geometries: N=3 for a dipole or sphere, N=2 for a line (pipe or cylinder), and N=1 for a plane or thin sheet (dike or sill). The depth of the point source lies between the top and center of the source. Non-integer scaling indices are a function of distance and present transitional features between the ideal source geometries [12]. A scaling index N>3 corresponds to a signal that decays faster than a dipole, suggesting contributions from higher orders, implying a non-uniformly magnetized source.

Fig 1. Locations of the studied lunar isolated magnetic anomalies. The shown magnetic field strength at 30 km height was predicted from the model of [13].

We focus on five isolated strong lunar magnetic anomalies (Fig.1) that show similar geometries and total field strengths > 5 nT at 30 km height in the recent lunar magnetic field models [13-15]. When deriving the scaling indices, we use the model of surface vector mapping [13] as primary because the other two models [14,15] use the equivalent source approach, which already imposes assumptions on source geometry. We extract the radial component of the strongest peak of the studied anomalies in the height range of 27—33 km in 0.1 km intervals and derive the best-fit point source depth and scaling indices (Table 1).

Table 1. Scaling indices and source depth of the studied lunar magnetic anomalies

Among the studied anomalies, Reiner Gamma, Airy, and Descartes show N>3, suggesting non-uniform magnetized sources and inaccurate corresponding paleopoles. These observations are consistent with swirls (surface reflectance anomaly) associated with Reiner Gamma and Airy, which indicate complex field geometry at the surface. Crisium anomaly shows a scaling index equivalent to dipole (N=3.0), while Abel anomaly (N=2.3) is consistent with a source geometry between sphere- and pipe-like sources.

Our results suggest that the Crisum and Abel anomalies can be reasonably approximated by uniform magnetized sources, thus enabling an accurate paleopole reconstruction. Beak et al. [5,6] use a dipole source to model the Crisium anomaly (consistent with the derived scaling index N=3) and estimate a paleo south pole at ∼45^◦N70^◦E. The paleo north pole of the Abel anomaly derived using Parker’s method [7] is located at ∼42^◦N114^◦E. Together, these results indicate that the lunar magnetic paleopole was offset by more than 40 degrees from the present geographic pole and reversed at least once between the formation periods of the Crisium and Abel anomalies.

Estimated source depths further constrain the origins of the studied anomalies. The Crisum and Abel anomalies are consistent with emplacement of iron-rich impactor-derived materials [5,6,8]. Reiner Gamma, Airy, and Descartes anomalies do not show an association with impact basins, and combined with N>3, may reflect multi-stage magmatic processes involving magnetization under varying ambient field directions. In particular, the magmatic origin of Reiner Gamma is consistent with the multi-phase magmatic activities of the region [16]. These results provide new constraints on the structure and origin of lunar magnetic anomalies and implications for their detection and interpretation in upcoming lunar missions, such as Lunar Vertex and Chang’e 7.

Reference

[1] Weiss & Tikoo, Science (2014). [2] Tsunakawa, H. et al. JGR-Planets (2015). [3] Ravat, D. et al. JGR-Planets (2020).  [4] Wieczorek, M. et al., NVM-2 (2023). [5] Beak, S. et al., JGR-Planets (2017).  [6] Beak, S. et al., JGR-Planets (2019). [7] Oliverira, J. and Wieczorek, M., JGR-Planets (2017). [8] Hood, L., Icarus (2011). [9] Chaffee, T. et al., JGR-Planets (2025).[10] Thompson, D., Geophysics (1982). [11] Reid, A. & Thurston J., Geophysics (2014) [12] Florio, G. et al., Geophys. Prospect. (2009). [13] Tsunakawa, H. et al., JGR-Planets (2015) [14] Ravat, D. et al., JGR-Planets (2020). [15] Hood, L. et al., JGR-Planets (2021). [16] Hiesinger, H. et al., JGR-Planets (2003).

How to cite: Yang, X. and Mittelholz, A.: Scaling analysis of strong lunar magnetic anomalies, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-497, https://doi.org/10.5194/epsc2026-497, 2026.

EPSC2026-497

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Since the Moon does not possess a dense atmosphere, its surface directly interacts with surrounding charged particles. In addition, photoelectrons and secondary electrons are emitted from the surface in response to incident photons and charged particles. To evaluate the direct interaction between the lunar surface and the charged particles, it is important to obtain the energy spectra of these particles, including photoelectrons. In this presentation, we introduce a numerical model of electrons emitted from the lunar surface due to solar irradiation. The input of the model is the solar irradiation flux, and it includes some physical and chemical parameters associated with photoemission. The model also considers Auger electrons, which are emitted from an atom following the emission of an inner-shell electron and possess characteristic energies. This model can be applied to various topics at the lunar surface, including surface charging. Surface charging is caused by incoming and outgoing currents and is characterized by the surface potential, which varies to balance incoming and outgoing electric currents. The lunar surface potential can be estimated by comparing model outputs with electron observations above the lunar surface. We also present applications of the model to potential estimation.

How to cite: Kato, M., Harada, Y., Xu, S., Poppe, A., Halekas, J., Yoshifumi, S., Nishino, M., Yokota, S., Takahashi, F., and Shimizu, H.: Developing a numerical model of photo-emitted electron energy spectra and its applications, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-1214, https://doi.org/10.5194/epsc2026-1214, 2026.

EPSC2026-1214

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