Planetary Science Research Articles

Effect of Cage Occupancies on Molecular Vibrations of Methane in Structure H Clathrate Hydrate: Ab Initio Molecular Dynamics Simulation.

The structure H (sH) of methane hydrate, which has a distinctive structure with large (LL) cages capable of encapsulating multiple methane molecules, has been suggested as a methane reservoir in large icy bodies such as Titan, making it important in planetary science. This high-pressure phase, which exists in the GPa range, lends itself to the study of methane states and dynamics using powerful experimental techniques such as IR and Raman spectroscopy. However, the interpretation of the vibrational spectra of methane in the sH structure has been challenging because of the spectral complexities. The signals attributed to the methane molecules in the LL cage, as well as those of the other two cage types, overlap in the spectra. In this study, we investigated the microscopic origins of the shape of the C-H stretching vibration spectrum of methane in the LL cage using ab initio molecular dynamics (AIMD) simulations. For a single methane molecule in the LL cage, the ν3 band of the C-H stretching mode was observed at a higher frequency typical of isolated molecules in vacuum due to the large size of the LL cage. As the number of methane molecules in the LL cage increased beyond one, a tendency to blue-shift with increasing methane occupancy was observed, consistent with a loose-cage-tight-cage model. By characterizing the time correlation function of methane stretching vibrations based on the solvation number of methane and water molecules proximal to methane within the LL cage, we showed that the complicated spectral line shape observed in cases of higher methane occupancy in the LL cage resulted from the wider variation of the solvation shell states. Analysis of the solvation structures of the AIMD trajectories provided interpretations of the experimental spectral line shape, demonstrating the complementary nature of AIMD to the experiment and its effectiveness in analysis.

Young stellar objects from the LAMOST and ZTF surveys: Physical properties, classification, and light curve analysis

Context. The study of young stellar objects (YSOs) not only enhances our understanding of star formation and stellar evolution, but also contributes to broader areas of astrophysics, including planetary science, galactic dynamics, and astrochemistry. Aims. We aimed to comprehensively analyse 657 YSOs and provide their physical parameter measurements using data from Zwicky Transient Facility (ZTF) g- and r-band light curves and the Gaia, WISE, 2MASS, and LAMOST databases. Specifically, we sought to identify periodicity in the light curves and classify the YSOs based on the Q – M variability plane, which enabled us to quantify flux asymmetry and quasi-periodicity. Methods. To achieve our objectives, we conducted a meticulous examination of the light curves obtained from the ZTF and estimated the physical parameters of the YSOs. These parameters were discerned by integrating stellar model atmosphere grids, photometric data, Gaia DR3 parallaxes, and pre-main-sequence evolutionary tracks. We employed the Q – M variability plane to classify the YSOs and determine the presence of periodic patterns. Additionally, we analysed the distribution of variability slope angles in the colour-magnitude diagram (CMD) to discern patterns associated with extinction-driven and accretion-related variability. Results. Our analysis revealed significant findings regarding the variability patterns and physical characteristics of the YSOs. Among the 657 objects analysed, 37 exhibited periodic variability and 2 displayed multi-period behaviour. Furthermore, we identified distinct variability patterns, including quasi-periodic symmetry, quasi-periodic dipping, aperiodic dipping, bursting behaviour, stochastic variability, and long-timescale variations. Notably, the distribution of variability slope angles in the CMD varied between dippers and bursters, indicating different underlying variability drivers. Additionally, we observed that YSOs classified as classical T Tauri stars and weak-line T Tauri stars exhibited contrasting light curve characteristics, with Class II YSOs displaying asymmetry and Class III YSOs showing (quasi-)periodic variations. These findings underscore the importance of considering variability patterns when classifying and determining the nature of YSOs.

ICC-BiFormer: A Deep-Learning Model for Near-Earth Asteroid Detection via Image Compression and Local Feature Extraction

Detecting near-Earth asteroids (NEAs) is crucial for research in solar system and planetary science. In recent year, deep-learning methods have almost dominated the task. Since NEAs represent only one-thousandth of the pixels in images, we proposed an ICC-BiFormer model that includes an image compression and contrast enhancement block and a BiFormer model to capture local features in input images, which is different from previous models based on Convolutional Neural Network (CNN). Furthermore, we utilize a larger input size of the model, which corresponds to the side length of the input image matrix, and design a cropping algorithm to prevent NEAs from being truncated and better divide NEAs and satellites. We apply our ICC-BiFormer model into a dataset of approximately 20,000 streak and 40,000 non-streak images to train a binary classification model. The ICC-BiFormer achieves 99.88% accuracy, which is superior to existing models. Focusing on local features has been proven effective in detecting NEAs.

The high power laser facility at beamline ID24-ED at the ESRF

ABSTRACT This paper describes technical details and new scientific opportunities offered by the new High Power Laser Facility at the ESRF, opened to users since 2022. This facility enables laser-induced dynamic compression experiments probed by ultra-fast X-ray Absorption Spectroscopy at beamline ID24-ED. This capability allows to reach and probe more extreme pressure and temperature states and higher strain rates with respect to static compression, addressing open questions in fundamental, planetary and material science.

Follow the Trace: Becoming a Seismo-Detective with a Campus-Based Raspberry Shake Seismometer

Abstract Seismic signals, whether caused by earthquakes, other natural phenomena, or artificial noise sources, have specific characteristics in the time and frequency domains that contain crucial information reflecting their source. The analysis of seismic time series is an essential part of every seismology-oriented study program. Enabling students to work with data collected from their own campus, including signals from both anthropogenic and natural seismic sources, can provide vivid, practical examples to make abstract concepts communicated in classes more concrete and relevant. Data from research-grade broadband seismometers enable us to record time series of vibrations at a broad range of frequencies; however, these sensors are costly and are often deployed in remote places. Participation in the Raspberry Shake citizen science network enables seismology educators to record seismic signals on our own campuses and use these recordings in our classrooms and for public outreach. Yale University installed a Raspberry Shake three-component, low-cost seismometer in the Earth and Planetary Sciences department building in Summer 2022, enabling the detection of local, regional, and teleseismic earthquakes, microseismic noise, and anthropogenic noise sources from building construction, an explosive event in a steam tunnel, and general building use. Here, we discuss and illustrate the use of data from our Raspberry Shake in outreach and education activities at Yale. In particular, we highlight a series of ObsPy-based exercises that will be used in courses taught in our department, including our upper-level Introduction to Seismology course and our undergraduate classes on Natural Disasters and Forensic Geoscience.

New Approaches on the Theory of Planetary Sciences: Applications of Non-Classical Equations of Mathematical Physics for Plasma Models of Jupiter’s Magnetosphere

In this paper, considered non-classical equations of mathematical physics are applied in the fields of astronomy and astrophysics in the case of plasma models of Jupiter’s magnetosphere. It is known that non-classical equations of mathematical physics have applications in gas dynamics, aerodynamics, hydrodynamics, and magneto-hydrodynamics. According to comparisons and observation results of Pioner-10, 11, and Voyager 1-2, considered mathematical models of Jupiter’s magnetosphere, which is cold plasma, as searches of Jupiter’s Io. At first, the mathematical justification of the physical process of Io concerning plasma was described by a non-classical equation of the Keldysh type. For this reason, using MHD equations for the derivation of the model equations of cold plasma and hot plasma on Jupiter’s magnetosphere. In the region tail of Jupiter given analyses of basic model equations of the Jupiter magnetosphere for the equilibrium between magnetic force, pressure gradient, and centrifugal force in the presence of plasma rotations. Additionally, based on the basic theoretical and observational results, the role of the Alfven Mach number with a constant Euler potential parameter in the region tail of Jupiter’s magnetosphere proves the justification of the steady magneto-hydrodynamic equilibrium. As agreed previously in the results of observation Voyager 1,2. Therefore, in the magnetosphere, Jupiter’s hot and cold plasma describe the same class equation of Keldysh-Tricomi types. In this case, the exact solution is obtained by integrals, which are first expressed as analytical formulas. Theoretical aspects of the model hot and cold plasma on the tail magnetosphere contain concepts of reconnection, which connects lost mass from Jupiter’s Io. Such an effect reconnection coronal problem as Parker’s also occurs by lost temperature and energy dissipation. Lorentz force, supported by means of solar wind, changes cold plasma to hot plasma in cases where a magnetic disk acts as a balancing mechanical equilibrium to retain cold-hot plasma. For motivation, both mathematical and physical, we used some figures, a table, and an appendix. Note that considered approaches to the theory of planetary sciences at first time applicable for Jupiter.

The Art of Doing Fieldwork on the Moon

How �early-career planetary scientists are preparing to support the astronauts who will return to the lunar surface and beyond.

Infrared Photodissociation Spectroscopy of Water-Tagged Ions with a Widely Tunable Quantum Cascade Laser for Planetary Science Applications.

This work presents a benchtop method for collecting the room temperature gas phase infrared (IR) action spectra of protonated amino acids and their isomers. The adopted setup uses a minimally modified commercial electrospray ionization linear ion trap mass spectrometer (ESI-LIT-MS) coupled to a broadband continuous wave (cw) quantum cascade laser (QCL) source. This approach leverages messenger assisted action spectroscopic techniques using water-tagged molecular ions with complex formation, irradiation, and subsequent analysis, all taking place within a single linear ion trap stage. This configuration thus circumvents the use of multiple mass selection and analysis stages, cryogenic buffer cells, and complex high-power laser systems typically called upon to execute these techniques. The benchtop action spectrometer is used to collect the 935-1600 cm-1 (6.2-10.7 μm) IR action spectrum of a collection of amino acids and a dipeptide with results cross referenced against literature examples obtained with a free electron laser source. Recorded IR spectra are used for the analysis of binary mixture samples composed of constitutional isomers α-alanine and β-alanine with ratios determined to ∼4% measurement uncertainty without the aid of a front-end separation stage. This turn-key QCL-based approach is a major step in showing the viability of tag-based action spectroscopic techniques for use in future in situ planetary science sensors and general analytical applications.

Exploring toroidal anvil profiles for larger sample volumes above 4 Mbar.

With the advent of toroidal and double-stage diamond anvil cells (DACs), pressures between 4 and 10 Mbar can be achieved under static compression, however, the ability to explore diverse sample assemblies is limited on these micron-scale anvils. Adapting the toroidal DAC to support larger sample volumes offers expanded capabilities in physics, chemistry, and planetary science: including, characterizing materials in soft pressure media to multi-megabar pressures, synthesizing novel phases, and probing planetary assemblages at the interior pressures and temperatures of super-Earths and sub-Neptunes. Here we have continued the exploration of larger toroidal DAC profiles by iteratively testing various torus and shoulder depths with central culet diameters in the 30-50µm range. We present a 30µm culet profile that reached a maximum pressure of 414(1) GPa based on a Pt scale. The 300K equations of state fit to our P-V data collected on gold and rhenium are compatible with extrapolated hydrostatic equations of state within 1% up to 4 Mbar. This work validates the performance of these large-culet toroidal anvils to > 4 Mbar and provides a promising foundation to develop toroidal DACs for diverse sample loading and laser heating.

Micro-sample Nd isotopic measurement on reference rock powders via the thermal ionization mass spectrometer Nd+ mode

The Sm–Nd isotopic system has been broadly utilized for dating and tracing in earth and planetary sciences. However, low Nd+ ionization efficiency permanently hinders precise and accurate measurements on small amounts of Nd samples. So far, isotopic measurement of micro-amount Nd sample via thermal ionization mass spectrometry (TIMS) Nd+ mode was mostly performed on Nd reference solutions, but less on natural rock or mineral samples. In the present study, analytical procedures to measure isotopic composition via the TIMS Nd+ mode were designed for natural rock powders by using 1–5 ng pure Nd. The analytical technique was refined through low-blank sample digestion, small-column chemistry for Nd extraction from matrix elements, loading Nd using purified H3PO4 solution, and careful heating of filaments before data acquisition. Measurements on small Nd amounts (1 ng–5 ng) of either the JNdi-1 reference solution or four reference rock powders yielded satisfactory results of 143Nd/144Nd value with respect to precision and accuracy. The analytical results agree well with the recommendation values of the reference materials within analytical errors and the internal precision is better than ±0.005 % (2RSE). When using 1 ng or 2 ng Nd amounts, 144Nd ion flow can remain stable in a signal intensity of >100 mV, and without the assistance of an additional ionization enhancer. Therefore, the analytical procedure, featured by low procedural blank (about 10–22 pg), high Nd+ ionization efficiency, and easy operation, has broad prospects for the application of Nd isotope in single-grain minerals or micro-samples.

Compact off-axis reflective optical system design combining freeform mirror and freeform detector

Minimizing system size and weight without sacrificing the desired imaging performance is a crucial and challenging goal in the design of off-axis optical systems. In this paper, we propose a design concept that combines freeform mirror and freeform detector to achieve more compact off-axis optical systems. Initially, by applying nodal aberration theory, the optimal focal surface shape for off-axis systems is demonstrated to be an off-axis paraboloid or even a freeform surface, rather than the commonly assumed spherical shape. Subsequently, we show the ability of the design concept to reduce off-axis system volume through a design example of a fast and wide-field off-axis three-mirror system. Results indicate that, under the same design parameters and imaging quality, the design with a freeform detector is 80% smaller than that with a flat detector in terms of volume. Finally, the bending capability of the freeform detector presented in this paper is ensured through finite element analysis, and its surface accuracy is achievable based on the current precision level of curved detector fabrication. The proposed design concept holds promise for application in planetary science, where the imaging performance of the instrument is highly required and the size and weight are strictly limited.

Reflecting on 5 Years at the Helm of <em>JGR: Planets</em>

The outgoing Editor-in-Chief of JGR: Planets reflects on the position of planetary sciences within AGU and the dedication of the planetary science community to supporting sound and insightful science.

Development of non-destructive isotope measurement of the natural galena (PbS) using negative muon beams

In Earth and planetary science, Pb isotopic composition is well known to play a key role in deciphering the origin and evolution of materials because they provide unique chronological and/or indigenous regional information as a radiogenic daughter nuclide from U and Th. To determine such an isotopic composition, mass spectrometers have been widely used over several decades, which requires a destructive/consuming treatment such as sputtering, laser ablation and thermal ionization. Here, we first report the non-destructive Pb isotopic measurement of natural galena (PbS) using the energy shift of muon-induced characteristic X-rays. The observed Pb isotopic composition of the natural galena is in good agreement with that obtained by conventional mass spectrometry. Such a muon-based Pb isotopic analysis method is expected to be applied to identify the production area of archaeological artefacts (e.g. bronze products), where non-destructive analysis is highly desirable compared to conventional mass spectrometry.

Automatic segmentation of radar data from the Chang’E-4 mission using unsupervised machine learning: A data-driven interpretation approach

Chang’E-3, Chang’E-4 and Chang’E-5 were the first planetary missions with in-situ ground-penetrating radar (GPR) in their scientific payloads. Apart from the Chang’E missions, in-situ GPR has also been used in the Martian missions Tianwen-1 and Perseverance, establishing GPR as a mainstream and pivotal tool in the new era of planetary exploration. Despite its widespread use in planetary science, interpreting GPR data from the Chang’E-4 mission is still challenging, with varying and ambiguous interpretations offered by different researchers. This is primarily due to the complexity and heterogeneity of the Lunar subsurface, which results to a difficult to interpret radagram with low signal-to-clutter ratio. Clutter masks potential targets and makes interpretation a laborious and highly subjective process. To tackle this, we interpret the GPR data from Chang’E-4 mission using a novel processing paradigm based on un-supervised machine learning. A set of statistical attributes is initially calculated locally for different sliding windows in the investigated radagram. Subsequently, these statistical features are clustered into groups using un-supervised machine learning. The segmented radagram highlights boundaries between different formations, and reveals hidden structures previously unseen using typical processing approaches. The proposed framework is fully automatic and objective, facilitating processing, and increasing the overall reliability of the final interpretation.

Exciting Planetary Exploration, Planetary Science but also Earth Sciences

Exciting Planetary Exploration, Planetary Science but also Earth Sciences

Postprocessing Workflow for Laboratory Diffraction Contrast Tomography: A Case Study on Chromite Geomaterials.

Texture stands as a fundamental descriptor in the realms of geology and earth and planetary science. Beyond offering insights into the geological processes underlying mineral formation, its characterization plays a pivotal role in advancing engineering applications, notably in mining, mineral processing, and metal extraction, by providing quantitative data for predictive modeling. Laboratory diffraction contrast tomography (LabDCT), a recently developed 3D characterization technique, offers nondestructive measurement of grain phases including their morphology, distribution, and crystal orientation. It has recently shown its potential to assess 3D textures in complex natural rock samples. This study looks at improving on previous work by examining the artifacts and presents a novel postprocessing workflow designed to correct them. The workflow is developed to rectify inaccurate grain boundaries and interpolate partially reconstructed grains to provide more accurate results and is illustrated using multi-scan examples on chromite sands and natural chromitite from the Upper Group 2 Reef layer in South Africa. The postcorrected LabDCT results were validated through qualitative and quantitative assessment using 2D electron back-scattered diffraction on polished sample surfaces. The successful implementation of this postprocessing workflow underscores its substantial potential in achieving precise textural characterization and will provide valuable insights for both earth science and engineering applications.

Next Generation Seismic Source Detection by Computer Vision: Untangling the Complexity of the 2016 Kaikōura Earthquake Sequence

AbstractSeismic source locations are fundamental to many fields of Earth and planetary sciences, such as seismology, volcanology and tectonics. However, seismic source detection and location are challenging when events cluster closely in space and time with signals tangling together at observing stations, such as they often do in major aftershock sequences. Though emerging algorithms and artificial intelligence (AI) models have made processing high volumes of seismic data easier, their performance is still limited, especially for complex aftershock sequences. In this study, we propose a novel approach that utilizes three‐dimensional image segmentation—a computer vision technique—to detect and locate seismic sources, and develop this into a complete workflow, Source Untangler Guided by Artificial intelligence image Recognition (SUGAR). In our synthetic and real data tests, SUGAR can handle complex, energetic earthquake sequences in near real time better than skillful analysts and other AI and non‐AI based algorithms. We apply SUGAR to the 2016 Kaikōura, New Zealand sequence and obtain five times more events than the analyst‐based GeoNet catalog. The improved aftershock distribution illuminates a continuous fault system with extensive fracture zones beneath the segmented, discontinuous surface ruptures. Our method has broader applicability to non‐earthquake sources and other time series image data sets.

Uranus Orbiter and Probe: A Radio Science Investigation to Determine the Planet’s Gravity Field, Depth of the Winds, and Tidal Deformations

The most recent Planetary Science and Astrobiology Decadal Survey has proposed Uranus as the target for NASA’s next large-scale mission. The interior structure and atmosphere of the planet are currently poorly understood, and objectives for investigating Uranus’s deeper regions and composition are highly ranked. Traditionally, gravity science has served as one of the primary means for probing the depths of planetary bodies and inferring their internal density distributions. In this work, we present precise numerical simulations of an onboard radio science experiment designed to determine Uranus’s gravity field and tidal deformations, which would offer a rare view into the planet’s interior. We focus on the mission’s orbital planning, discussing crucial parameters such as the number of pericenter passes, orbital inclination, and periapsis altitude necessary to meet the gravity measurement requirements for a Uranus orbiter. Our findings suggest that eight close encounters may be sufficient to determine the zonal gravity field up to J 8 with a relative accuracy of 10%, if the trajectory is optimized. This would allow for the decoupling of the gravity field components due to interior structure and zonal winds. Additionally, we find that the expected end-of-mission uncertainty on Uranus’s Love number k 22 is of order ∼0.01 (3σ). This level of accuracy may offer crucial information about Uranus’s inner state and allow for discriminating between a liquid and solid core, thus shedding light on crucial aspects of the planet’s formation and evolution.

Capillary Processes in Extraterrestrial Contexts

AbstractThe Earth is no longer the only known celestial body containing one or more liquid phases. The Cassini spacecraft has discovered seas of hydrocarbons at the surface of Titan, while a series of corroborating evidences argue in favor of the existence of an aqueous ocean beneath the icy crust of several moons. Capillarity embraces a family of physical processes occurring at the free surface of a liquid. These phenomena depend on the liquid properties and on the local planetary conditions. Capillarity may have important direct or indirect implications on the geoscientific and astrobiological points of view. In this paper, we discuss capillarity physics among solar system objects and expected consequences for planetary science.

Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Planetary and cometary atmospheres.

The study of planets and small bodies within our Solar System is fundamental for understanding the formation and evolution of the Earth and other planets. Compositional and meteorological studies of the giant planets provide a foundation for understanding the nature of the most commonly observed exoplanets, while spectroscopic observations of the atmospheres of terrestrial planets, moons, and comets provide insights into the past and present-day habitability of planetary environments, and the availability of the chemical ingredients for life. While prior and existing (sub)millimeter observations have led to major advances in these areas, progress is hindered by limitations in the dynamic range, spatial and temporal coverage, as well as sensitivity of existing telescopes and interferometers. Here, we summarize some of the key planetary science use cases that factor into the design of the Atacama Large Aperture Submillimeter Telescope (AtLAST), a proposed 50-m class single dish facility: (1) to more fully characterize planetary wind fields and atmospheric thermal structures, (2) to measure the compositions of icy moon atmospheres and plumes, (3) to obtain detections of new, astrobiologically relevant gases and perform isotopic surveys of comets, and (4) to perform synergistic, temporally-resolved measurements in support of dedicated interplanetary space missions. The improved spatial coverage (several arcminutes), resolution (~ 1.2'' - 12''), bandwidth (several tens of GHz), dynamic range (~ 10 5) and sensitivity (~ 1 mK km s -1) required by these science cases would enable new insights into the chemistry and physics of planetary environments, the origins of prebiotic molecules and the habitability of planetary systems in general.