We searched the Mars InSight seismic data for signals that would indicate the presence of an inner core, such as the inner-core boundary-reflecting phase, PKiKP, and the bottom-side outer-core-reflection, PKIKKIKP. For this, we analysed the highest-quality events from the seismically most active region (Cerberus Fossae) detected on Mars. Using source-array methods, we compute vespagrams and associated F-vespagrams, wherein a strong energy peak at a specific time and horizontal slowness indicates a coherent seismic phase. We validated our method on body wave phases seen earlier by the InSight team, such as SS. Application to PKiKP and PKIKKIKP produces coherent signals for a range of candidate inner-core radii, specifically 200–300 km and 500–600 km for PKiKP and 100--600~km for PKIKKIKP. This suggests that the interpretation of inner-core seismic signals is not unique and, consequently, there is no definitive evidence confirming the existence of an inner core on Mars.

The circulation of fluid mass associated with Venus' atmospheric dynamics leads to periodic changes in surface displacement and gravitational field. As deformation depends on its interior structure and the applied load, observations of the shape of Venus can help constrain models of solid-body structure and atmospheric dynamics. In this study, we investigate whether surface deformations associated with atmospheric loading are detectable from orbit. To this end, we combine a general circulation model of Venus' atmosphere with a novel approach to the solution of the quasi-static momentum equations in the coupled gravito-elastic problem for a threedimensional planet. We find that atmospheric loading produces surface displacements up to +/- 2 cm that may be detectable near equatorial regions by the VERITAS (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy) mission, which is expected to perform high-precision surface displacement measurements in specific locations. Complimentary to this, we explore whether surface displacement measurements can be employed to image surface pressure changes, which can be used to inform Global Climate Models of Venus and thereby advance our understanding of its atmosphere and, in turn, weather and climate. Finally, our results offer guidance for future mission design by establishing quantitative thresholds for surface displacement observations to be used to infer structural properties of Venus' interior and its atmospheric dynamics.

It is usually taken for granted that mutual synchronization of a tidal two-body system is attained through tidal recession, assuming the reduced Hill sphere is not reached. However, synchronization can be achieved also via tidal approach, provided the Roche limit is not crossed. For each of the two scenarios, we derive the condition under which the evolving synchronicity radius catches up with the tidally evolving orbit. We consider the two scenarios for the Pluto-Charon system and examine the impact-origin hypothesis of Charon's formation against capture. Based on geophysical evidence, we propose that capture appears more likely. Motivated by this conclusion, we investigate both analytically and numerically the capture scenario, wherein the orbital evolution of Charon starts at a higher altitude than present and undergoes tidal descent. We also consider the possibility that Pluto's initial prograde spin underwent a reversal by a tidally approaching retrograde Charon. Depending on the initial conditions, we observe temporary locking of Charon into higher spin-orbit resonances (3:2 to 7:2) during the first 0.5 Myr of the system's evolution. Owing to a greater initial separation between the partners, the power dissipated in each of them turns out to be much lower than in the case of tidal recession of bodies of the same internal structure. The greater initial separation also results in lower tidal stress, which may explain the absence of tidally generated fracture patterns.

Electromagnetic sounding coupled with experimental measurements of electrical conductivity (EC) can provide valuable constraints on the thermochemical state of Earth's lower mantle. Here, we report a new set of experimentally determined EC values of pyrolite, a candidate composition of the lower mantle, between 25 and 80 GPa at room temperature and high temperature between 1,200 and 2,300 K using a laser-heated diamond anvil cell combined with impedance spectroscopy. To maintain and better constrain the geometry of the experimental assembly, we used focused ion beam-cut discs of a pre-synthesized pyrolitic sample. Our results reveal a monotonic increase in EC with pressure, in contrast to earlier measurements that suggested a spin-transition-induced conductivity drop in the mid-lower mantle. We also identify intrinsic voltage- and pressure-related time-dependent behavior that are likely expressions of nonlinear grain-boundary conduction and stress-driven relaxation processes, respectively. To our knowledge, this is the first report of such behavior in geological materials and may represent a previously unrecognized source of uncertainty in earlier high-pressure EC data sets. Finally, we compare predictions based on our experimental findings against the radial EC structure derived from analysis of 10 years of satellite magnetic data from the ESA Swarm mission, with improved resolution in the lower mantle down to 2,200 km. We find that the measured EC of pyrolite is consistent with the geophysically inferred conductivity structure.

The structure and nature of Earth’s transition zone, which is delineated by the transformation of olivine to its higher-pressure polymorphs, exerts a strong influence on material transfer between upper and lower mantle. Mars, however, because of its relatively large core, is only expected to exhibit the equivalent of Earth’s uppermost transition zone seismic discontinuity. We searched the InSight seismic data for marsquakes and impacts located in an epicentral distance range favorable for detection of seismic phases that have interacted with Mars’s olivine transition (midmantle) discontinuity. Through application of careful data selection criteria and processing schemes, we found 13 events in the distance range in which body waves are expected to refract through the midmantle of Mars. Although triplicated body waves are potentially present in seven events, the distance distribution is insufficient to allow for unambiguous detection of the triplicated waveform pattern associated with the midmantle discontinuity. Comparison of travel times of the observed waveforms with predictions from recent Mars models indicates the possible presence of a midmantle discontinuity located between 987 and 1052 km or 1075 and 1122 km depth, in which the uncertainty comes from our inability to reliably distinguish first from secondary arrivals.

Surface mass loads produce a wide spectrum of deformation responses in planetary bodies that can be exploited to probe material properties in planetary interiors. In particular, the redistribution of fluid mass associated with Venus’s atmospheric dynamics leads to periodic changes in the Venusian surface displacements and thus gravitational field. These periodic variations could potentially be detected by upcoming Venus missions, e.g., VERITAS (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy) and EnVision, which are expected to greatly improve our knowledge of Venus’s gravity field. By combining a state-of-the-art general circulation model of Venus’s atmosphere with a novel approach to the solution of the quasi-static momentum equations in the coupled gravito-elastic problem, we explore the sensitivity of the atmospheric loading response to mantle structure. In addition, we investigate the effect of 3-D crustal and lithospheric variations on Venus’s gravity field and the tidal and load Love numbers. Preliminary results suggest that an accurate estimation of the time-varying gravity field and surface displacements can provide important constraints on the interior structure of Venus through the measurement of the load Love numbers.

It is usually assumed that mutual synchronisation of a tidal two-body system happens through tidal recession, assuming the reduced Hill sphere is not reached. However, synchronisation can be achieved also via tidal approach, provided the Roche limit is not crossed. For each of the two scenarios, hereafter referred to as Scenario 1 and Scenario 2, respectively, we derive the condition under which the evolving synchronicity radius catches up with the tidally evolving orbit. We consider these two scenarios for the Pluto-Charon system, examine the impact origin hypothesis of Charon's formation, and propose that capture is a likelier option. We investigate Scenario 2, both analytically and numerically, where the orbital evolution of Charon starts at a higher altitude than present and undergoes tidal descent. In Scenario 2, the greater initial orbital separation between the partners reduces tidally induced thermal processes and fracturing, as compared to Scenario 1. In several study cases, we also observe temporary locking of Charon into higher spin-orbit resonances (3:2 to 7:2) in the first 0.5Myr of the system's evolution.

Cratons are characterized by thick mantle roots that have experienced high degrees of partial melting, resulting in a cold, strong, and buoyant mantle compared to its oceanic counterpart. The extent of chemical variability within cratonic roots, the role of cratons in insulating the mantle over time and subsequent triggering of continental break‐up, however, remains debated. To better understand the lithospheric and asthenospheric compositional variability of cratons, we combine phase equilibrium computations with the inversion of P‐to‐s and S‐to‐p receiver function waveforms and fundamental‐mode Rayleigh wave dispersion data recorded at 53 globally distributed seismic stations in different tectonic settings with a focus on cratonic regions. Because existing binary basalt‐harzburgite models are unable to account for the variability in Mg# (MgO/[MgO + FeO]) and Mg/Si ratios recorded in xenoliths from cratonic regions, we propose an extension of the binary model that is based on nominally pyroxenite, lherzolite and dunite. The retrieved mantle lithospheric compositions have elevated Mg# (∼90–93) compared to asthenospheric mantle (Mg# ∼89), consistent with their having undergone differing degrees of melt extraction at mean pressures of 3–4 GPa. There are no indications for systematic differences in mantle composition or thermal structure with craton age or location. Instead, we find that the potential temperature of the asthenosphere beneath cratons is roughly 50°C cooler than the surrounding ambient mantle. This suggests that the insulating (i.e., heating) effect of continents may not be as prominent as implied by dynamical studies simulating the exchange of heat and material across the mantle.

A basal magma ocean (BMO) has been suggested to form as a consequence of cumulate overturn following crystallization of an initial global magma ocean. As a consequence of enrichment in iron and heat-producing elements (HPE), the BMO stabilizes gravitationally at the base of the planetary mantle, affecting the efficiency of mantle convection and crustal production. Seismic data collected during the recent Mars InSight mission provide compelling evidence for the presence of a molten silicate layer at the bottom of the Martian mantle. Here, we study the role of a BMO on the long-term evolution of Mars's interior using two-dimensional geodynamic models in spherical annulus geometry. We compare our model predictions with available observational constraints, including crustal HPE enrichment, seismically constrained present-day crustal and lithospheric thicknesses, and mantle temperatures. Among the parameters explored, we find that the interstitial porosity, which controls the initial HPE distribution between the BMO and the mantle, plays an important role on mantle thermal structure throughout Mars's evolution. Models with an intermediate interstitial porosity (20%-60%), and with a reference mantle viscosity of Pas (at ) provide the best match to the most observational constraints. This suggests that HPE partitioning between mantle and BMO has not been controlled by end-member fractional crystallization of the initial magma ocean, and that chemical re-equilibration must have occurred to some extent during cumulate overturn. Crustal growth constraints nevertheless remain difficult to reconcile independent of HPE enrichment of the BMO. Better understanding of the earliest stages of Martian differentiation is required.

The terrestrial planets are believed to have accreted from chondritic meteorites of widely varying composition. Yet, making planets from known meteoritic material has proved elusive, be it their nucleosynthetic isotopic anomalies, bulk chemistry or geophysical properties. Because of the inherent non-uniqueness of meteoritic mixing models based on isotopes alone, combining geochemical and geophysical observations is key to identifying the nature of the building blocks of the terrestrial planets. Here, we integrate the recent proliferation of data in the form of geophysical measurements pertaining to Mars's interior structure from the recent InSight mission including its astronomic-geodetic response, the chemical and isotopic compositions of undifferentiated and differentiated meteorites, and observational constraints on trace element abundances (K/Th ratio) in order to make new inferences on the constitution and provenance of Mars. Using stochastic mixing models of meteoritic material, we find that similar to 0.02% of mixtures, consisting primarily of ordinary-and enstatite chondrites and, to a lesser extent, achondritic material, are able to reproduce the isotopic signature of Mars. Of these, however, none match the geophysical or Mg/Si and K/Th constraints, indicating that Mars is unlikely to have formed from known unmodified meteoritic material. Instead, relatively oxidised building blocks that are intrinsic to the inner solar system and underwent evaporation/condensation processes that lead to volatile-element depletion patterns unlike those in any known meteorite group, would be consistent with the isotopic, geochemical and geophysical properties of Mars.

Ocean tide loading (OTL) brings about recurring deformation of the Earth’s surface. Some of the OTL harmonics, e.g. M2, O1, Mf, cause sufficiently large surface displacement to be registered by the Global Navigation Satellite Systems (GNSS). These displacements are sensitive to the interior structure of the planet in a broad range of temporal and spatial scales making them a potentially unique source of information about the planet’s response at low frequencies. Comparison between observations and predictions for 1D elastic Earth models result in discrepancies of up to 3 mm (Bos et al., 2015, Martens et al., 2016). Spatial coherency of these discrepancies hints to 3D interior structure as one of the main sources of such residuals.In this context, we present a framework to invert OTL observations for 3D crustal and mantle structure based on a trust-region Newton-type iterative algorithm. Furthermore, we resort to the adjoint approach as an efficient means of computing the gradient for the high-dimensional model space. Focusing on the design of the inverse algorithm, we constrain ourselves to deformations of an isotropic elastic planet, which are governed by a self-adjoint forward operator. In order to assess the robustness of the method, we perform a suite of 3D synthetic inversions that mimic the distribution of the GNSS stations in South America. Preliminary results indicate enhanced sensitivities to the crustal and upper mantle density and elastic properties in the vicinity of the coastlines.

Here we critically examine the geophysical and geochemical properties of the Moon in order to identify the extent to which dynamical scenarios satisfy these observations. New joint inversions of existing lunar geophysical data (mean mass, moment of inertia, and tidal response) assuming a laterally- and vertically homogeneous lunar mantle show that, in all cases, a core with a radius of 300±20 km (∼0.8 to 1.5

The Jiangmen Underground Neutrino Observatory (JUNO) started physics data taking on 26 August 2025. JUNO consists of a 20-kton liquid scintillator central detector, surrounded by a 35 kton water pool serving as a Cherenkov veto, and almost 1000 m^2 of plastic scintillator veto on top. The detector is located in a shallow underground laboratory with an overburden of 1800 m.w.e. This paper presents the performance results of the detector, extensively studied during the commissioning of the water phase, the subsequent liquid scintillator filling phase, and the first physics runs. The liquid scintillator achieved an attenuation length of 20.6 m at 430 nm, while the high coverage PMT system and scintillator together yielded about 1785 photoelectrons per MeV of energy deposit at the detector centre, measured using the 2.223 MeV γ from neutron captures on hydrogen with an Am-C calibration source. The reconstructed energy resolution is 3.4

Mars's atmosphere has theoretically been predicted to be strong enough to continuously excite Mars's background-free oscillations, potentially providing an independent means of verifying radial seismic body-wave models of Mars determined from marsquakes and meteorite impacts recorded during the Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport (InSight) mission. To extract the background-free oscillations, we processed and analyzed the continuous seismic data, consisting of 966 Sols (a Sol is equivalent to a Martian day), collected by the Mars InSight mission using both automated and manual deglitching schemes to remove nonseismic disturbances. We then computed 1-Sol-long autocorrelations for the entire data set and stacked these to enhance any normal-mode peaks present in the spectrum. We find that while peaks in the stacked spectrum in the 2-4 mHz frequency band align with predictions based on seismic body-wave models and appear to be consistent across the different processing and stacking methods applied, unambiguous detection of atmosphere-induced free oscillations in the Martian seismic data nevertheless remains difficult. This possibly relates to the limited number of Sols of data that stack coherently and the continued presence of glitch-related signal that affects the seismic data across the normal-mode frequency range (similar to 1-10 mHz). Improved deglitching schemes may allow for clearer detection and identification in the future.

With the deployment of a seismometer on the surface of Mars as part of NASA’s InSight mission,the Seismic Experiment for Interior Structure (SEIS) has been collecting continuous data since early 2019.The primary goal of InSight is to improve our understanding of the internal structure and dynamics of Mars, inparticular crust, mantle, and core. Here we describe constraints on the structure of the mantle of Mars basedon inversion of seismic body wave arrivals from a number of low-frequency marsquakes.We consider 8 of the largest (moment magnitude is estimated to be between 3 and 4) low-frequency events withdominant energy below 1 Hz for which P- and S-waves are identifiable, enabling epicentral distance estimation.The 8 events occur in the distance range 25-75 degrees. Body wave arrivals that include the main P- and S-waves,surface reflections (PP, PPP, SS, SSS), and core reflections (ScS) are picked using a set of complimentary methodsthat allows to check for consistency. The resultant set of differential travel times (PP-P, PPP-P, SS-S,...) aresubsequently inverted for radial profiles of seismic P- and S-wave velocity, core size and mean density, and epicentrallocation of the events. To determine interior structure, we rely on independent methods as a means of assessing therobustness of the results.We present a radial velocity model for the upper mantle of Mars, with implications for the thermo-chemical evolutionof the planet that match a cooling, differentiated body, and a thick lithosphere. Based on the location of the events,we are able to constrain structure to the core-mantle-boundary, including the size of the core and its meandensity that point to large liquid and relatively light core, implying a significant complement of light alloyingelements. Our estimate of the average crustal thickness as seen by all events is compatible with the local crustalthickness at the InSight landing determined from observations of converted phases.

Determining the composition of Earth's lower mantle, which constitutes almost half of its total volume, has been a central goal in the Earth sciences for more than a century given the constraints it places on Earth's origin and evolution. However, whether the major element chemistry of the lower mantle, in the form of, e.g., Mg/Si ratio, is similar to or different from the upper mantle remains debated. Here we use a multidisciplinary approach to address the question of the composition of Earth's lower mantle and, in turn, that of bulk silicate Earth (crust and mantle) by considering the evidence provided by geochemistry, geophysics, mineral physics, and geodynamics. Geochemical and geodynamical evidence largely agrees, indicating a lower-mantle molar Mg/Si of ≥1.12 (≥1.15 for bulk silicate Earth), consistent with the rock record and accumulating evidence for whole-mantle stirring. However, mineral physics–informed profiles of seismic properties, based on a lower mantle made of bridgmanite and ferropericlase, point to Mg/Si ∼ 0.9–1.0 when compared with radial seismic reference models. This highlights the importance of considering the presence of additional minerals (e.g., calcium-perovskite and stishovite) and possibly suggests a lower mantle varying compositionally with depth. In closing, we discuss how we can improve our understanding of lower-mantle and bulk silicate Earth composition, including its impact on the light element budget of the core. ▪The chemical composition of Earth's lower mantle is indispensable for understanding its origin and evolution.▪Earth's lower-mantle composition is reviewed from an integrated mineral physics, geophysical, geochemical, and geodynamical perspective.▪A lower-mantle molar Mg/Si of ≥1.12 is favored but not unique.▪New experiments investigating compositional effects of bridgmanite and ferropericlase elasticity are needed to further our insight.

The InSight mission collected four years of seismic data from Mars, providing unprecedented data on the planet’s interior. Two seismic events – one marsquake and one meteorite impact – took place on the opposite side of Mars to InSight’s broadband seismometer [1]. These two far-side events were initially located using mantle-transiting PP and SS waves, but we demonstrate that their waveforms contain additional seismic arrivals which are sensitive to the properties of the Martian core. Using multiple seismic methods, we obtain SKS differential travel times for S0976a, a distant marsquake, and S1000a, a distant impact. SKS travels through Mars’ core as compressional waves and is therefore sensitive to its elastic properties. We use these differential travel times to build the first seismically informed models of Mars’ core [2]. The core velocity of Mars is low: 4.9-5.0 km/s at the CMB. We use our seismic results to estimate the fraction of light elements in Mars’ core, finding a high fraction of sulphur is needed, together with lesser amounts of oxygen, carbon and hydrogen. In addition to the SKS signals observed, the waveforms from S1000a contain evidence for a seismic wave which diffracts along a molten silicate layer at the base of the Martian mantle and also reflects from the core-mantle boundary. The presence of a basal silicate molten layer has implications for the areotherm, and could reduce both estimates of metallic core’s radius and its fraction of light elements [3]. The SKS detections reported provide information about the physical properties of the liquid core of Mars. A solid inner core at the centre of Mars is unlikely; we assess what structures inside the Martian core can be excluded based on existing data and models. [1] Horleston et al., 2022. Seism. Rec., 2(2), 88-99 [2] Irving et al., 2023. PNAS, 120, e2217090120 [3] Samuel et al., 2023, Nature, 622, 712–717

Objective: To estimate the diagnostic accuracy of Elastography to distinguish between benign and malignant lymph nodes of the head and neck region; taking histopathology as the gold standard. Study Design: Cross-sectional study. Place and Duration of Study: Radiology Department, Pakistan Institute of Medical Sciences, Islamabad Pakistan, from Jul to Oct 2021. Methodology: Elastography, Color Doppler and B-mode ultrasound were used to examine fifty participants with enlarged cervical lymph nodes. Elastographic forms (1–5) were characterized based on the hard area in the cervical lymph nodes. In addition, the shear wave elastography of cervical lymph nodes was evaluated. Outcomes of diagnostic sono-elastographic parameters were matched with the histopathology of lymph nodes as a reference of standard. Results: The mean age of patients was 30.50±8.95 years. Out of 50 patients, 31(62%) were men, and 19(38%) were women. Out of 50 patients enrolled, 29(58%) showed benign lymph nodes, while 21(42%) showed malignant lymph nodes on elastography.All 50 patients underwent a biopsy for histopathology. Conclusion: Ultrasound elastography has high diagnostic accuracy in differentiating benign from malignant lymph nodes. Therefore, it can be used as a reliable and non-invasive modality for diagnosing lymphadenopathy in the cervical region. Keywords: Cervical, Elasticity imaging techniques, Elastography, Lymph nodes, Lymphadenopathy, Neck, Ultrasound