Mélanie Drilleau

Determining the crust–mantle boundary of the Moon has been an important topic in lunar interior studies. However, strong seismic scattering in the lunar subsurface has made it challenging to identify clear crustal reflections or converted seismic phases. In addition, the limited epicentral distances of recorded moonquakes restrict direct constraints on the lunar crust from first‐arriving seismic waves. Consequently, the Moon's crustal structure remains poorly constrained due to the limited availability of seismological evidence. Through joint analysis of seismic, topographic, and gravity data, while accounting for seismic velocity variations predicted by thermal modeling, we obtain new ray tracing results and present new insights on the lunar crust and upper mantle structure. Our results constrain the average global Moho depth to 35.1 2.6 km. Additionally, our results indicate slightly lower seismic velocities in the uppermost mantle than previously estimated, at approximately 7.5 km/s. Introducing the thermal model into the inversion further allows us to constrain the Moon's surface heat flow, with an average value of 10.7 0.8 , which is consistent with the heat flow measurements obtained during the Apollo mission. The refined crustal thickness provides a structural basis for estimating the Moon's bulk Al and Th abundances. The model also better constrains the porosity, density, and radiogenic heat production of the lunar crust, and provide new implications for a pyroxene‐rich upper mantle composition.

Meteoroid impacts are frequent on the Moon and provide valuable natural seismic sources for probing the lunar interior. However, accurately locating lunar impacts remains challenging because intense scattering within the highly fractured lunar crust obscures direct P- and S-wave arrivals. Coda-based localization methods exploit scattered energy, but their accuracy has so far been limited by the parameterization of the method. In this study, we reformulated a coda-based localization approach within the framework of seismic quanta scattering theory by introducing four distance proxies: peak amplitude, rise time, differential arrival time, and the overall coda shape. By jointly combining these proxies, we obtain locations that agree well with independent travel-time-based solutions. We then apply the method to locate forty-nine high-amplitude local impact events recorded by the Apollo seismic network, while also estimating their localization uncertainties and impact momenta. Our results demonstrates that coda waves contain robust distance information even in a strongly scattering lunar crust, enabling reliable impact localization and providing new constraints on the connection between seismic source properties and impact crater formation.

Over the 1440-sol mission of the NASA InSight lander, more than 1900 seismic events (marsquakes) were recorded and catalogued by the Marsquake service [1]. These events have enabled the determination of both the bulk interior structure [e.g. 2,3,4] and hinted at more curious aspects, for example, a basal mantle layer [5,6], mantle plumes/dynamics [e.g. 7] and crustal heterogeneities [e.g. 8]. Much evidence for such features has come from a small select group of events, owing to their superior signal quality or magnitude. On top of this, only a handful of events have generated deep mantle phases [9].Given that InSight is only a single station, it is necessary to develop methods that extract information from a broader range of marsquakes to further develop our understanding of event origins and interior structure. To this end, we propose a clustering approach for the P-wave coda of events. This method targets the relatively underused high frequency energy of events, typically dominated by scattering [8] and more affected by environmental noise [10]. The clustering approach effectively acts as a selective event stacking to improve signal to noise ratios, identifying only the most similar events to create the stack. Using this method, we identify a set of P-wave coda features and track their evolution over distances. We will explore the obtained families of P-waves morphology to infer the potential range of event sources and help improve marsquake classifications [1]. This is of interest to probe questions on whether they are generated from tectonic or impact sources [1], with recent research proposing the possibility of a swarm source for certain events [11]. This interpretation, in turn, has implications for the variability of Mars’s crustal structure. Furthermore, the signal to noise ratio improvement highlights delayed energy arrivals, providing new characteristics to infer structural complexities from scattering behaviour [8]. References[1] Ceylan, Savas, et al. "The marsquake catalogue from InSight, sols 0–1011." Physics of the Earth and Planetary Interiors 333 (2022): 106943.[2] Knapmeyer-Endrun, Brigitte, et al. "Thickness and structure of the Martian crust from InSight seismic data." Science 373.6553 (2021): 438-443.[3] Khan, Amir, et al. "Upper mantle structure of Mars from InSight seismic data." Science 373.6553 (2021): 434-438.[4] Stähler, Simon C., et al. "Seismic detection of the martian core." Science 373.6553 (2021): 443-448.[5] Samuel, Henri, et al. "Geophysical evidence for an enriched molten silicate layer above Mars’s core." Nature 622.7984 (2023): 712-717.[6] Khan, Amir, et al. "Evidence for a liquid silicate layer atop the Martian core." Nature 622.7984 (2023): 718-723. [7] Broquet, Adrien, and Jeffrey C. Andrews-Hanna. "Geophysical evidence for an active mantle plume underneath Elysium Planitia on Mars." Nature Astronomy 7.2 (2023): 160-169.[8] Menina, S., et al. "Stratification of heterogeneity in the lithosphere of Mars from envelope modeling of event S1222a and near impacts: Interpretation and implications for very‐high‐frequency events." Geophysical Research Letters 50.7 (2023): e2023GL103202. [9] Horleston, Anna C., et al. "The far side of Mars: Two distant marsquakes detected by InSight." The seismic record 2.2 (2022): 88-99.[10] Stott, Alexander E., et al. "Machine learning and marsquakes: a tool to predict atmospheric-seismic noise for the NASA InSight mission." Geophysical Journal International 233.2 (2023): 978-998.[11] Dahmen, Nikolaj L., et al. "Analysis of high frequency Marsquake swarms informed by deep learning." Journal of Geophysical Research: Planets 131.1 (2026): e2025JE009229.

The internal structure of the Moon is key to understanding its formation, evolution, and bulk composition. In particular, determining the structure of the crust–mantle interface (Moho), including its lateral variations, is of significant importance, but current knowledge is still insufficient to fully constrain it. To address this, we used seismic wave arrivals from impact events, which yield constraints on the crust at both the impact sites and the Apollo stations, to invert for local crustal thickness. Based on a series of assumed crust and mantle density models, we compared Moho depths inferred from global gravity recovery and interior laboratory gravity data with those from seismic observations. Although the gravity‐derived results broadly capture the overall Moho relief, local discrepancies remain, with differences reaching up to 10 km in the vicinity of the Apollo 17 Saturn IVB impact site. These results may reflect regional geological anomalies and highlight the importance of incorporating multiple seismically constrained crustal thickness estimates as anchors in gravity inversions. Using seven seismic anchor points and assuming an upper mantle velocity of 7.68 , an upper mantle density of 3,280 , and a crustal density of 2,693 , we obtain an average lunar crustal thickness of 43.6 1.9 km. The findings also provide valuable guidance for future global 3D modeling of the Moon.

More than 50 years after Apollo, the Moon deep interior structure is still not well known. Several seismic experiments are expected on the Moon surface in the coming year (Chang’e 7, Chandrayan, Artemis III, FSS and SPSS). All of those seismometers are not expected to resolved the seismic background of the Moon and their performances are not meeting the International Lunar Network requirements (10-11 m.s-2/sqrt(Hz)).To meet this requirement, IPGP is developing an optical seismometer operated in open loop. Its mechanical oscillator is a 1Kg proof mass suspended by a 4 cross blades hinge and a leaf spring with extremely low damping. Its displacement sensor is a Michelson interferometer, associated to a narrow bandwidth laser source and an optical phase readout electronic inherited from fiber optics gyroscope. This instrument will be candidate for all flight opportunities around 2030 (launch date).The first prototypes performances tests demonstrated the potential of this technology. But it also revealed that stray light inside the interferometer is limiting its performance. Different techniques of characterization of the stray light are compared: in situ coherent detection, characterization using a delay line and short coherency length light source. Tests results are compared to simulation.Analysis of the stray light impact on the performances through the optical phase readout electronic modulation scheme shows the impact on performances. Expectation and performances potential of the next prototypes generation is discussed.

Understanding Mars' deep interior is essential to reconstruct its geological history, thermal evolution, and present‐day dynamics. To this end, the NASA InSight mission has provided unprecedented seismic observations. However, strong trade‐offs between temperature and composition in seismic interpretations continue to limit our ability to resolve interior models. To address this challenge, we account for electromagnetic induction data from Mars Global Surveyor as an additional, independent constraint. We develop a joint probabilistic inversion framework that simultaneously fits seismic body wave arrival times, electrical conductivity, the Love number, and the moment of inertia. A key feature of our approach is the integration of Mars' long‐term thermal evolution within the forward model, along with mineral physics and petrology data, to better constrain geodynamical parameters. We explore three different mantle compositions (Sanloup et al., 1999, https://doi.org/10.1016/s0031‐9201(98)00175‐7 ; Taylor, 2013, https://doi.org/10.1016/j.chemer.2013.09.006 ; Yoshizaki & McDonough, 2020, https://doi.org/10.1016/j.gca.2020.01.011 ) and consider both radially homogeneous and heterogeneous (with a basal molten layer (Samuel et al., 2023, https://doi.org/10.1038/s41586‐023‐06601‐8 )) mantle scenarios. For homogeneous mantle models, two families of solutions emerge regardless of the bulk composition: one with low Mg content and high potential temperature, which better reproduces electrical conductivity data due to a thicker lithosphere, and another with high Mg content and lower potential temperature. Models with a heterogeneous mantle reproduce electrical conductivity data less accurately, due to thinner lithospheres, and the mantle composition of Yoshizaki and McDonough (2020, https://doi.org/10.1016/j.gca.2020.01.011 ) appears to be less consistent with the full data set. To further refine models of Mars' interior, future efforts should focus on acquiring electromagnetic data with reduced uncertainties and seismically constraining more precisely the depth of mantle discontinuities associated with mineral phase transitions.

Seismic determination of the Moon's crustal thickness is crucial for understanding its formation, composition, and evolution. Additionally, crustal thicknesses below seismic stations serve as anchoring points for 3D crustal thickness maps derived from gravity and topography field variations. However, strong seismic scattering inside the Moon can prevent seismic waves reflected on, or converted at, crust and upper mantle discontinuities from reaching the surface without interacting with scatterers. This study estimates Auto‐Correlation Functions (ACF) of all channels of Apollo seismometers during the coda of high‐signal‐to‐noise seismic events. As expected for a strongly scattering medium, Apollo stations S12 and S15 do not detect late arrivals in the ACF indicative of waves reflected on internal discontinuities. However, station S16 and, to a lesser extent, station S14 show stable late arrivals in the ACF. Arrivals at 14.2 and 27.1 s and at 23.9 and 50.6 s in the ACF of vertical and horizontal mid‐period channels of station S16 are interpreted as and waves reflected at mid‐crustal and crust‐mantle interfaces. A seismic crust and upper mantle model beneath station S16 fits the arrival times of and waves with realistic seismic velocities and ratios ranging from 1.65 to 1.88. The crustal thickness is non‐uniquely estimated at 53 km below station S16. Our results are also compatible with significant variations in the properties of the interfaces, or in strength of seismic scattering between Apollo stations.

The internal structure of the Moon is key for understanding its formation, evolution, and bulk composition. In particular, determining the structure of the crust-mantle interface (Moho) is of significant importance but still requires further constraints. To address this, we used seismic wave arrivals from impact events, which carry a unique signature of the crust at both the impact sites and the Apollo stations, to invert for local crustal thickness. The meteoroid impact locations and crustal velocity were investigated simultaneously during the inversion. By comparing the lateral variations of Moho depth obtained from seismic data with those derived from global gravity data, we find a general agreement in the overall Moho relief, although some local discrepancies remain. This study presents the first quantitative comparison between Moho depth models constrained by Apollo seismic observations and those inferred from GRAIL gravity data, demonstrating that combining multiple seismically constrained crustal thickness estimates as anchoring points with gravity data provides a more accurate and refined determination of the global lunar crustal thickness.

The seismometer of the InSight NASA discovery mission recorded more than 1,300 seismic events on Mars, grouped into different families according to their frequency content. Here, we present a method to detect quake nests based on time domain correlation of long‐duration waveforms (520 s). Event doublet candidates are first detected on the 2.4 Hz local resonance, and then validated by simultaneous detections on different components and different frequency bands. We provide a detailed analysis of the impact of noise on these detections. Our method revealed a triplet of very high frequency events (S0334b/S0334c/S0343a). These observations demonstrate that quake nests do occur on Mars, validating an active seismic area at 26° epicentral distance, which is interpreted as Cerberus Fossae, and that both impacts and quakes generate the very high frequency‐type seismic events. These repeating waveforms could be used to test noise removal methods applied to InSight seismic data.

Introduction:In response to the exploratory call for missions within ESA’s science program, we propose the ECLIPSE mission to deploy a European geophysical station with seismometers and electromagnetic sensors on the lunar surface. Although data from the Apollo seismic network and subsequent geodetic studies provided initial models of the Moon's internal structure, its interior remains highly complex and not yet well understood. Numerous missions are being planned, with the aim of establishing permanent lunar bases. In this context, lunar seismology is of critical importance, and recent milestones—such as China’s Chang’e missions and India’s Chandrayaan-3—mark the beginning of a new era in lunar seismic exploration. NASA’s Farside Seismic Suite (FSS), part of the CLPS CP-12 flight, is set to perform the first seismic measurements on the Moon’s far side, while the Lunar Environment Monitoring Station (LEMS), included in Artemis 3, will deploy the first human-operated seismometer since Apollo. Meanwhile, China is preparing to send a seismometer aboard Chang’e 7 and later Chang’e 8. These efforts will lay the groundwork for an international lunar seismic network over the next decade.ECLIPSE aims to set up a European seismic station by deploying a three-axis seismometer on the lunar surface. The vertical axis will feature the last available unit of the Very Broad Band vertical (VBBZ) seismometer — the most sensitive flight-ready seismometer ever built — previously flown on InSight [1], and in preparation for FSS [2]. The horizontal components will consist of two geophones. The seismic suite will be complemented by a radiometer, magnetometer, electric field sensor, short period vertical geophone and a camera. Science investigations:ECLIPSE is designed to meet four key science objectives for a nominal mission duration of four months (an extended mission will however be considered, with focus on network science):(1) Determine the interior structure of the Moon to better understand the formation and evolution of the Earth-Moon System. ECLIPSE will greatly advance our understanding of the Moon’s deep interior by using a single seismic station to measure S-P differential travel times from Deep Moonquakes, as well as secondary seismic phases. These data will improve tomographic models, enhance precision in seismic attenuation analysis, and help investigate the presence of partial melt in the mantle. The mission may also detect seismic phases that traverse or reflect off the lunar core, offering new constraints on its size. Locally, high-sensitivity instruments will characterize crustal structure through receiver functions and noise autocorrelations. Electromagnetic data will enable magnetic sounding to infer mantle electrical conductivity structure. By combining seismic and magnetic field data, ECLIPSE will refine models of the Moon's crust and mantle mineralogy, state and temperature.(2) Understand the current lunar bombardment rate. ECLIPSE will significantly improve estimates of the current meteoroid impact rate, a key factor for dating lunar and planetary surfaces. By combining ground-based [3] and space-borne (e.g., LUMIO) optical flash detections with ECLIPSE’s seismic recordings and uniquely identified seismic events, the mission significantly enhances impact detection capabilities. These observations will refine micrometeoroid flux estimates and improve constraints on impactor mass and velocity.(3) Monitor real-time environment affecting operation for potential future stable astrophysical and physics observatories. ECLIPSE will constrain the impact hazard using flux estimates from Objective 2 and monitor the vibrational environment for any possible future astronomical observatories, ensuring the safety of future human exploration. By constraining the fluctuations of the solar constant with the radiometer, correlations with the seismic noise and ground thermal contraction effects will be assessed, to better understand and mitigate the lunar seismic noise in the deci-hertz bandwidth, which is crucial for designing future gravitational wave detectors on the Moon.(4) Characterize the electrostatic environment at the surface of the Moon. Measuring DC electric fields on the Moon is key to understanding interactions between the regolith, plasma, and dust. Solar radiation and wind create strong surface potential differences, leading to complex charging phenomena. These fields, reaching hundreds of volts per meter, can lift dust and affect mission hardware. Accurate field measurements are essential for validating models and preparing for future lunar missions, including those requesting laser links potentially affected bv the levitated dusts. Instrument suite:The instrument suite is composed of eight instruments with TRL>= 7, inherited from past space missions (Table 1). Instrument Provider Heritage Very Broad Band seismometer (VBBZ) IPGP, France InSight Spare unit [1]; Same packaging as the lunar FSS [2] Two geophones in horizontal configuration (GEOH) ISAS, Japan DragonFly-LunarA; Rebuilt sensor [4] Geophone in vertical configuration (GEOZ) ISAE-Supaero, France Same as RAMSES mission Electrical field sensor (Efly) LATMOS, France MicroARES; Rebuilt sensor [5] Radiometer (RAD) ROB, Brussels PICARD; Rebuilt sensor [6] Magnetometer (MAG) IWF Graz, ÖAW, Austria, TUBS, Germany BepiColombo, MMS, SOSMAG [7] Camera (CAM) Politecnico di Milano, Italia Hera/Milani; RAMSES Cubesat Acquisition electronics (Ebox) ETH Zurich, Switzerland InSight Spare Unit [8] Table 1: Equipment listMission configuration:Two mission configurations are currently under consideration. (1) The first option focuses on using high-TRL components, including a structure and thermal system originally developed by JPL for the FSS mission [2], combined with avionics derived from CubeSat technology. The primary constraint of this approach lies in...