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Magnetic hole (MH), sometimes referred to as magnetic bottle, exhibits strong magnetic fields at its neck but weak magnetic fields at its belly. Such structure has been widely reported in the solar wind and the Earth's magnetosphere, but has not been reported at Jupiter. Here, for the first time, we report two MHs in the Jupiter's magnetosphere by utilizing measurements of the Juno mission, with one existing in the dawn side and the other existing in the dusk side. We find that the electron pitch‐angle distribution inside the MHs can be either cigar‐type or pancake‐type. The cigar‐type distribution probably appears at the belly of the MH, whereas the pancake‐type distribution probably appears at the neck. Our analyses of the depression of magnetic fields inside the MHs support such a conjunction. These results have advanced our understanding of the transient structure and its related electron dynamics in the giant planets' magnetosphere. Plain Language Summary: Examining the electron pitch‐angle distribution (PAD) can help us better understand the electron dynamics in planetary magnetosphere. Up to now, there has been no report of magnetic holes (MHs) at Jupiter and thus the electron dynamics in such place is unknown. Here using the Juno measurements, we for the first time report two MHs in the Jupiter's magnetosphere. We find the PA distribution of suprathermal electrons inside the MHs can be either cigar type or pancake type, and further explain their formation processes by using a magnetic bottle model. Our study is very useful to understand electron dynamics in Jupiter's magnetosphere. Key Points: For the first time, we report magnetic holes (MHs) in the Jupiter's magnetosphereWe found both cigar and pancake distribution of electrons inside magnetic holesUsing a magnetic bottle model, we reasonably explain the formation of these two distributions and provide observation evidence [ABSTRACT FROM AUTHOR]

The long‐standing "energy crisis" at the giant planets refers to the anomalous heating of planetary thermospheres compared to the available energy from solar irradiance. The coupling between planetary magnetospheres and their upper atmospheres is thought to address these crises, though the sources and pathways of energy transport have not been fully explored at each system. In particular, the total available energy from the upstream solar wind at each planet has not been comprehensively quantified. Here we apply recently developed models of energy conversion by magnetic reconnection and the Kelvin‐Helmholtz instability to each of the Giant Planets, providing estimates of the average external energy inputs for each system between 1985 and 2020. We find that external energy associated with solar‐wind‐magnetospheric coupling significantly exceeds that from solar extreme ultraviolet photons. While internal energy sources are known to dominate at Jupiter and Saturn, external sources may be significant at Uranus and Neptune. Plain Language Summary: The upper atmospheres of Jupiter, Saturn, Uranus, and Neptune are all hotter than would be predicted by their exposure to sunlight alone. The space plasma environment around each planet provides an additional reservoir of energy that can be used to provide this heating. Here we quantify the average energy input to each planetary system due to variation of the photons and plasmas emitted from the Sun. We find that the interaction between a planetary magnetic field and the solar interplanetary magnetic field provides a strong source of external energy at each of the planets, on average significantly more than that of light from the Sun. Key Points: Solar wind‐magnetospheric‐coupling provides higher energy input than solar extreme ultraviolet at the giant planetsSolar activity drives solar‐wind‐magnetospheric coupling much more strongly than planetary seasonThe solar wind may drive the energy input to the upper atmospheres at Uranus and Neptune [ABSTRACT FROM AUTHOR]

Jupiter and Saturn exhibit alternating east‐west jet streams. The origin of these zonal flows has been debated for decades. The high‐precision gravity measurements by the Juno mission and the grand finale of the Cassini mission have revealed that the observed zonal flows may extend several thousand kilometres deep and stop around the transition region from molecular to metallic hydrogen, suggesting the magnetic braking effect on zonal flows. In this study, we perform a set of magnetohydrodynamic simulations in a spherical shell with radially variable electrical conductivity to investigate the interaction between magnetic fields and zonal flows. A key feature of our numerical models is that we impose a background dipole magnetic field on the anelastic rotating convection. By varying the strength of the imposed magnetic field and the vigor of convection, we investigate how the magnetic field interacts with the convective motions and the convection‐driven zonal flows. Our simulations reveal that the magnetic field tends to destroy zonal flows in the metallic hydrogen and suppress zonal flows in the molecular envelope, while the magnetic field may enhance the radial convective motions. We extract a quantitative relation between the magnetic field strength and the amplitude of zonal flows at the surface through our simulations, which roughly matches the observed magnetic field and zonal wind speed of Jupiter and Saturn. This discovery provides support from a new perspective for the scenario of deep convection‐driven zonal winds which are confined to the molecular hydrogen layers in giant planets. Plain Language Summary: This study explores the mysterious east‐west jet streams, known as zonal flows, observed on Jupiter and Saturn. Data from the Juno and Cassini missions suggested that these flows extend deep into the planets, stopping where hydrogen transitions from a molecular to a metallic state. Here we conduct computer simulations in a spherical shell geometry to understand ho'w the magnetic fields and zonal flows interact in the deep interior of giant planets. We show that magnetic fields disrupt or weaken jet streams, but may enhance radial convective fluid motions. Crucially, our simulations provided a relation to link magnetic field strength with jet stream intensity at the surface, aligning well with real observations from Jupiter and Saturn. This supports the theory that the jet streams on these giant planets are driven by deep convection and are confined to the outer molecular hydrogen layers. Key Points: We show that the magnetic field suppresses zonal flows in the molecular layer and enhances convective motionsWe extract a scaling relation between the magnetic field and the zonal flow at the surface that matches observations of Jupiter and SaturnThis study provides alternative evidence that the zonal winds on gas planets are deep‐seated and convection driven [ABSTRACT FROM AUTHOR]

Asteroid 4 Vesta is typically thought to be the parent body of the HED (howardite, eucrite, and diogenite) meteorites due to spectral similarities. The discovery of asteroids far from Vesta with HED‐like spectra like (1459) Magnya and HED‐like meteorites (e.g., NWA 011) with anomalous oxygen isotopic values compared to typical HEDs is evidence that other Vesta‐like bodies formed. We broadly define a Vesta‐like body as a differentiated object with a crust composed primarily of low‐Ca pyroxene and plagioclase feldspar. We estimate the number of Vesta‐like bodies that did form by looking at the astronomical evidence; the oxygen isotopic, chemical, and petrologic evidence; and the iron meteorite evidence. Assuming that fragments of Vesta were scattered from Vesta by giant planet migration, we conservatively estimate that at least two Vesta‐like bodies (Vesta and the Magnya parent bodies) existed. From the oxygen isotopic, chemical, and petrologic evidence, we also conservatively estimate that seven Vesta‐like bodies formed. Analyses of iron meteorites indicate that there may be as many as 23 Vesta‐like bodies (Vesta, 10 magmatic iron groups, South Byron trio, Emsland/Mbosi duo, 10 ungrouped irons). This estimate from iron meteorites is most certainly an overestimation due to the existence of a number of non‐HED crustal/mantle fragments that potentially originated from bodies with magmatic iron cores. Using our three estimates as a guide, we predict that there were ~10 Vesta‐like bodies (including Vesta) that formed in the early solar system. Only Vesta remains intact with the others being disrupted early in solar system history. [ABSTRACT FROM AUTHOR]

Outward transport of plasma in the inner and middle magnetospheres of gas giants results from an interplay between mass loading from the inner dominant mass sources (volcanic moons), flux tube interchange in the centrifugally unstable magnetospheric plasma disk, turbulent heating of the plasma, and coupling between the equatorial plasma and the planetary upper atmosphere through magnetic field-aligned current loops and/or Alfven waves. We present a new analytical formalism describing large scale transport in gas giant systems, combining two historical approaches: radial diffusion of mass and energy through flux tube interchange, and angular momentum transport through corotation enforcement. Under the hypotheses of axisymmetry, steady-state, and multi-fluid plasma, we provide transport equations for total contents of flux tubes. They feature new transport parameters accounting for the latitudinal extent of the disk, and self-consistently include field-aligned potential drops in the magnetosphere-ionosphere coupling. Our general formalism has a wealth of applications, two of which are presented, corresponding to the cases of the two gas giants: the effect of interhemispheric asymmetries in the resistive and magnetic properties between the northern and southern ionospheres on the transport of angular momentum at Jupiter, and the influence of the plasma disk thickness on transport at Saturn. We apply our formalism to derive ionospheric parameters and reproduce the Juno and Cassini data. Further work will allow for more complete numerical solutions of our equations, with the aim of capturing the broad complexity of fast rotating magnetospheric systems which can be found inside and outside the Solar System. [ABSTRACT FROM AUTHOR]

We present observations of Uranus in northern spring with the Very Large Array from 0.7 to 5 cm. These observations reveal details in thermal emission from Uranus' north pole at 10s of bars, including a dark collar near 80°N and a bright spot at the polar center. The bright central spot resembles observations of polar emission on Saturn and Neptune at shallower pressures. We constrain the variations in temperature and NH3/H2S abundances which could explain these features. We find that the brightness temperature of the polar spot can be recreated through 5 K temperature gradients and/or 10× depletion of NH3 or H2S vapor between 10 and 20 bars, both consistent with the presence of a cyclonic polar vortex. The contrast of the polar spot may have increased since 2015, which would suggest seasonal evolution of Uranus' polar circulation at depth. Plain Language Summary: New radio telescope observations of Uranus several interesting features, including a compact feature at the center of the North Pole which appears warmer than its surroundings. This feature likely indicates the presence of a polar cyclone and shows similarities to polar features observed on other giant planets in the solar system. Key Points: Very Large Array observations in 2021 and 2022 reveal a bright, compact spot centered at Uranus' pole at several wavelengthsConstraints on horizontal temperature and composition gradients necessary to explain the polar emission structure are derivedInferred patterns in temperature, zonal wind speed and trace gas variations are consistent with the presence of a compact cyclonic vortex [ABSTRACT FROM AUTHOR]

The study of atmospheric electricity of the lower stratosphere and upper troposphere of the ice giant planets can help to understand several physical phenomena such as cloud formation, lightning generation, aerosols growth, or chemical composition. At these depths, galactic radiation is the main energy source able to ionize the atmospheric constituents and to produce a low altitude ionospheric layer that can be similar in magnitude to the upper ionosphere produced by solar radiation and auroral electrons. The presence of aerosols affects the ion‐neutral chemistry by capturing electrons and ions depending on the aerosol size and number density. Here, we present a new one dimensional ionospheric model of Uranus and Neptune able to calculate the number densities of electrons and ions as well as the charging of aerosols between 100 Pa and 4 × 105 Pa. Since the results depends upon the amount and size of the atmospheric aerosols, as well as on the flux of the incoming cosmic radiation, several aerosol models, solar‐cycle conditions, and the effect of the intrinsic magnetic field are considered. Plain Language Summary: Uranus and Neptune form the group of ice giant planets in our solar system. They are mainly composed of hydrogen, helium, and volatiles. These planets are the only ones that have not had a dedicated mission to study their atmospheres in situ. The most valuable information was obtained during the Voyager 2 encounters in 1986 and 1989. Such missions provided a wealth of information and raised important questions that have not been addressed yet. Here, we present a new model to calculate the density of electrical charges in the low‐altitude atmosphere in order to estimate electrical conductivity. We found that a low‐altitude ionosphere is created by cosmic radiation. The presence of aerosols can reduce the amount of electrons by more than three orders of magnitude compared to an aerosol‐free atmosphere. The results of this study can help to understand several important atmospheric processes, such as the formation of aerosols and clouds, as well as the generation of lighting. Key Points: A state model of ions and electrons in the lower ionosphere of Uranus and Neptune has been developedThe size and density distribution of aerosols strongly affect the number density of electrons and ionsThe measurement of the electrical conductivity can be used to study the lower ionospheres of Uranus and Neptune [ABSTRACT FROM AUTHOR]

This is a laboratory zonal‐jet study using a rotating water tank. The bottom topography has a tent‐shaped radial cross section designed to generate two critical latitudes, that is, two positions where βe, the radial gradient of the potential vorticity (PV), changes sign. This configuration is motivated by observations indicating that Jupiter and Saturn have not only multiple zonal jets, but multiple stable critical latitudes. It is known that "supersonic" critical latitudes (with respect to Rossby waves) are stable, whereas "subsonic" critical latitudes are posited to be unstable. Because Rossby waves are unidirectional, "supersonic" critical latitudes come in two varieties: Rossby Mach number MR > 1 and < 0, where the latter holds when the waves are directed downstream. Experiments focus on: (a) how do zonal jets emerge from localized forcing in a system with alternating PV gradients? and (b) what differences are there between the evolution of various types of critical latitudes? The water is forced by mass injection along one radius. Laboratory altimetry provides accurate, unobtrusive records of the circulations that reveal the emergence of counter‐propagating β‐plumes (Rossby‐wave envelopes), which expand into tank‐encircling zonal jets. The tank's negative βe zone (annulus) is characterized by MR ∼ 1. The weaker critical latitude adjusts its position by about 4% of the tank radius and maintains MR ∼ 1, similar to the state surmised for Jupiter and Saturn, whereas the stronger critical latitude vacillates while maintaining |MR| ≪ 1 and may be relevant to steep oceanic seamounts. Plain Language Summary: Jupiter is striped with dark and light bands called belts and zones, which are associated with its steady eastward and westward jet streams ("jets" for short). Entwined within these are long waves that would cause the jets to meander and buckle, like Earth's jet streams do, if it were not for guide rails that are buried inside the gas giant: the steady pressure ridges and troughs, called dynamic topography, that are associated with the planet's abyssal jets. This work employs an optical altimetry method for measuring the circulations in a rotating water tank without disturbing the flow. The tank's bottom topography is a tent‐shaped peak that encircles the tank like a donut and provides a Jupiter‐style guide rail. The flow is forced by injecting water from the holes of a submerged pipe that extends along one radius. Many different types of waves are recorded propagating away from this forcing, and the circulations are seen to evolve into alternating eastward and westward jets that encircle the tank. Where long waves travel upstream at about the same rate as the flow itself travels downstream, such that the waves are approximately stationary, the system exhibits Jupiter‐like characteristics. Key Points: Stability of jets is assured when critical latitudes (extrema of potential vorticity) are "supersonic" with respect to Rossby wavesMultiple stable critical latitudes on Jupiter and Saturn motivate this study of a rotating water tank with two built‐in critical latitudesLab altimetry records alternating jets forming from local forcing and distinguishes between Jupiter‐like and non‐Jupiter‐like environments [ABSTRACT FROM AUTHOR]

The temperatures of ions in the magnetospheres of Jupiter and Saturn were observed to increase substantially from about 10 to 30 planet radii. Different heating mechanisms have been proposed to explain such observations, including a heating model for Jupiter based on magnetohydrodynamic (MHD) turbulence with flux‐tube diffusion. More recently, an MHD turbulent heating model based on advection was shown to also explain the temperature increase at Jupiter and Saturn. We further develop this turbulent heating model by combining effects from both diffusion and advection. The combined model resolves the physical consistency requirement that diffusion should dominate over advection when the radial flow velocity is small and vice versa when it is large. Comparisons with observations show that previous agreements, using the advection only model, are still valid for larger radial distance. Moreover, the additional heating by diffusion results in a better agreement with the temperature observations for smaller radial distance. Plain Language Summary: The temperatures of ions in the magnetospheres of Jupiter and Saturn were observed to increase substantially near the planet. This suggests that there should be some heating sources to counter the cooling effect due to expansion. There have been several models trying to explain such observation using different heating mechanisms, including a heating model for Jupiter based on turbulence and diffusion effects, as well as a model based on advection effects for Jupiter and Saturn. We further develop a heating model by combining effects from both diffusion and advection. The combined model resolves the physical consistency requirement that diffusion should be stronger than advection nearer to the planet, but shifting to the opposite farther away. Comparisons with observations show that previous agreements using the advection only model are still valid, and are improved by including diffusion nearer to the planet. Key Points: A new model for the heating of the magnetospheres of Jupiter and Saturn by magnetohydrodynamic turbulence is developedThe model combines effects from diffusion and advection such that each is dominant when the radial velocity is small or large, respectivelyPredictions of the temperature and radial velocity profiles agree better with Jupiter and Saturn observations than previous models [ABSTRACT FROM AUTHOR]

Radiant energies of planets and moons are of wide interest in the fields of geoscience and planetary science. Based on long‐term multiinstrument observations from the Cassini spacecraft, we provide here the first observational study of Titan's global radiant energy budget and its seasonal variations. Our results show that Titan's radiant energy budget is not balanced over the Cassini era (2004–2017) with the absorbed solar energy (1.208 ± 0.008) × 1023 J larger than the emitted thermal energy (1.174 ± 0.005) × 1023 J. The energy imbalance is 2.9 ± 0.8% of the emitted thermal energy. Titan's global radiant energy budget is not balanced either at the timescales of Earth's years and Titan's seasons. In particular, the energy imbalance can be beyond 10% of the emitted thermal energy at the timescale of an Earth year. The energy imbalance revealed in this study has important impacts on Titan, which should be examined further by theories and models. Plain Language Summary: The radiant energy budget is a fundamental metric for planets and moons. Using the observations from the Cassini spacecraft, we first look at Titan's global radiant energy budget and its seasonal variations. Our study suggests Titan's global radiant energy budget is not balanced at the timescales of Earth years and Titan's seasons. The energy imbalance can help us better understand the characteristics of Titan (e.g., seasonal variations). Titan's energy imbalance also suggests that it is possible that there are more terrestrial planets and moons having unbalanced radiation budgets. Finally, Titan's time‐varying radiant energies imply that the internal heat of the giant planets needs to be reexamined by considering the temporal variations of radiant energies. Key Points: With Cassini multiinstrument observations (CIRS, ISS, and VMIS), we provide measurements of the seasonal variations of Titan's Bond albedoOur measurements suggest a net energy excess (2.9 ± 0.8% of the emitted energy) over the Cassini era (2004–2017) on TitanThe energy imbalance changes from an energy excess (10.7 ± 0.7%) in 2004–2005 to an energy deficit (−3.4 ± 0.6%) in 2017 [ABSTRACT FROM AUTHOR]

Knowledge of the elasticity of high‐pressure ice is key to constructing the internal structure of various planetary bodies. Here, we present direct experimental constraints on the single‐crystal elasticity of ice with 0.5 mol/L (0.9 mol.%) NaCl up to 98 GPa at 300 K. The change from ice‐VII to the dynamically disordered ice‐VII is characterized by an obvious softening of the longitudinal and bulk moduli between 42.4 and 54 GPa. Further transition to ice X at ∼64 GPa results in an apparent change in the pressure dependence for the elasticity. Using the obtained elasticity, our modeling reveals that the boundary between the ice‐VII layer and the silicate mantle or core in moderate‐size icy planetary bodies would be associated with a sudden velocity jump. In large planetary bodies, the change from ice X to the silicate layer will be characterized by an abrupt reduction in velocity. Plain Language Summary: High‐pressure ice, such as ice‐VII or ice X, is one of the major components in icy satellites, giant planets, and large ocean exoplanets. Experimental studies on the physical properties of high‐pressure ice are of particular importance for understanding the internal composition, structure, and dynamic evolution of these planetary bodies. Here, we provide direct experimental constraints on the single‐crystal elasticity of salty ice up to 98 GPa at 300 K. The transition from ice‐VII to the dynamically disordered phase and then to ice X is characterized by the anomalous variation in all the elastic constants followed by an apparent change in the pressure gradient of the elasticity. These results provide important information for the internal structure of icy planetary bodies. Key Points: We determined the single‐crystal elasticity of high‐pressure salty ice up to 98 GPa and 300 K using Brillouin scatteringThe elastic moduli of the high‐pressure ice exhibit anomalous softening between 42.4 and 54 GPaThe transition from ice‐VII to ice X is associated with an apparent increase in the pressure derivative of the elastic moduli [ABSTRACT FROM AUTHOR]

In the outer heliosphere, higher upstream Alfvénic Mach number (MA) values have been theorized to limit the solar wind forcing at all giant planet magnetospheres. To determine the true impact of MA on the ability for magnetopause reconnection to occur, we perform a comprehensive analysis using data collected throughout the heliosphere. We find that solar cycle variations in solar wind magnetic pressure lead to wide ranges of upstream MA in the outer heliosphere, where MA at solar maximum appears Earth‐like. These considerable MA variations combined with the significant magnetic dipole tilts at Uranus and Neptune suggest that magnetopause reconnection may yet play an important role at the ice giants, in particular at solar maximum. Plain Language Summary: As the Sun's magnetic field strength increases during solar maximum, so does the possibility for coupling between the solar wind and a planetary magnetic field. Through analysis of data from several spacecraft that have traversed the outer reaches of the solar system, we find that increased solar activity results in a stronger interplanetary magnetic field at all of the planets. We find that the highly tilted magnetic fields of the ice giants, that is, Uranus and Neptune, are most sensitive to these variations in solar activity such that their space environments may appear drastically different depending on when they are observed. Key Points: Spacecraft measurements from 0.3 to 75 AU are analyzed to investigate upstream Alfvénic Mach number variation throughout the solar systemIncreased solar activity reduces upstream Alfvénic Mach numbers and increases the probability of magnetopause reconnectionHighly tilted dipole axes at the ice giants can result in significant solar wind‐magnetospheric coupling during solar maximum [ABSTRACT FROM AUTHOR]

Images of the giant planets Jupiter and Saturn show highly turbulent storms and swirling clouds that reflect the intensity of turbulence in their atmospheres. Quantifying planetary turbulence is inaccessible to conventional tools, however, since they require large quantities of spatially and temporally resolved data. Here we show, using experiments, observations, and simulations, that potential vorticity (PV) is a straightforward and universal diagnostic that can be used to estimate turbulent energy transfer in a stably stratified atmosphere. We use the conservation of PV to define a length scale, LM, representing a typical distance over which PV is mixed by planetary turbulence. LM increases as the turbulent intensity increases and can be estimated from any latitudinal PV profile. Using this principle, we estimate LM within Jupiter's and Saturn's tropospheres, showing for the first time that turbulent energy transfer in Saturn's atmosphere is four times less intense than Jupiter's. Key Points: We present a new and universal diagnostic to reveal the intensity of turbulent energy transfer in planetary atmospheresWe show that turbulent energy transfer in Saturn's atmosphere is 4 times less intense than Jupiter's [ABSTRACT FROM AUTHOR]

Fifty years of collaboration between the authors are reviewed. Common themes cover magnetospheric magnetohydrodynamic phenomena: MHD waves, wave‐particle interactions, circulation, global modes and field line resonances in the terrestrial context, and magnetosphere‐moon interactions, transport processes, instabilities, and global structure in the magnetospheres of giant planets. Over the period reviewed, instrumentation has improved, particularly in particle detectors, and interpretations that seemed radical when first suggested are now supported by measurements and seem commonplace. Plain Language Summary: The authors have worked together for almost 50 years. They met when the existence of the magnetosphere, the volume surrounding the Earth in space that is structured by its planetary magnetic field, had been established for only a decade. They have succeeded since then in showing that, in a field where new discoveries were regularly happening, there is a very useful role for people who, paying attention to the strengths and weaknesses of instrumentation, can move back and forth between theory, simple modeling, data analysis, and back to theory. Magnetohydrodynamics, a theoretical tool that simplifies the description of space plasmas by focusing on averaged responses, has been their key discipline, but some of their key contributions have elucidated the critical role of the energetic particles that depart from average behavior. Through a mix of theory, interpretation of observations, and even leading spacecraft instrument teams, the authors have contributed to understanding most aspects of the large‐scale behavior of the magnetospheric systems at Earth, Jupiter, and Saturn. Key Points: Outline of development of many aspects of basic field and particle interactions in magnetospheresTheories of linear and nonlinear magnetospheric MHD waves and wave‐particle interactionsMHD of giant planet magnetospheres and magnetosphere‐moon interactions [ABSTRACT FROM AUTHOR]

Early gravity measurements performed by the Juno spacecraft determined Jupiter's low‐degree gravity harmonics, including the first estimate of the planet's north‐south asymmetric field. The retrieved information was used to infer that the strong zonal winds visible at the cloud tops must extend down a few thousand kilometers, where they are suppressed in the deep interior. The next frontier for the Juno gravity experiment includes, among other goals, the determination of Jupiter's small‐scale gravity field with high accuracy, and its relation to atmospheric circulation at shorter length scales. The geometry of the Juno closest approaches to the planet poses a challenge to this task, as they span latitudes between 4°N and 29°N over the course of the nominal mission. Since Doppler measurements are the most sensitive to gravity anomalies when the spacecraft is close to the body, observations of Jupiter's gravity field are mostly concentrated in the northern hemisphere, while the traditional spherical harmonic functions are not orthonormal over a latitudinal subdomain. Here we define customized Slepian functions, which are orthogonal in a specific latitude range and are optimized to represent Jupiter's local surface gravity at north latitudes. We show that with the new functions, the short‐scale latitudinal variability of the gravity field is resolved with high accuracy between 15°S and 45°N latitude. Furthermore, preliminary results show that the estimated values for the Slepian coefficients from the Juno data match the predictions obtained using thermal wind balance to relate the dynamical density anomalies and the winds with an optimized scale height. Plain Language Summary: Among the main scientific objectives of NASA's Juno mission is the determination of Jupiter's gravity field with high accuracy. The measurements are related to the planet's internal mass distribution and carry information about its structure and dynamics below the visible clouds. Gravity science observations from the first few close flybys of the spacecraft allowed for the determination of the long‐scale, global gravity field of the planet with unprecedented accuracy. On the other hand, the determination of the short‐scale, localized gravity field is challenging when using the traditional spherical harmonic function basis used in planetary geodesy. In fact, these functions are defined globally, whereas the Juno observations are geographically limited to the northern hemisphere. In this work we use the Slepian function basis, which is defined over a limited latitudinal region of the planet, to resolve the small scale variability of the northern gravity field of Jupiter. Key Points: Slepian orthonormal functions are used to estimate the localized short‐scale gravity field of Jupiter using Juno observationsThe determination of Jupiter's gravity field is tailored to the geometry of the Juno orbitThe measured localized short‐scale gravity field of Jupiter matches the prediction from a thermal wind model of the zonal jets [ABSTRACT FROM AUTHOR]

The depth of the jet streams seen in Jupiter's outer weather layer has long been debated, with alternative suggestions of confinement to the weather layer and extensions deep into the planet being considered. Interpretation of measurements from NASA's Juno probe have suggested that weather‐layer jets do extend deep into the planet, down to depths of 𝒪(3,000 km). However, this relies on the assumption that the jet profile does not change its spatial structure with depth, which may not be the case. In this work, we consider a simple 1.5‐layer shallow‐water model of Jupiter‐like jet streams, with prescribed deep jets in the lower layer, and look at the parameters affecting the strength of the coupling between the layers. We find the value of the Rossby deformation scale, LD, to be particularly important, not just in setting the magnitude of variations in layer depth, but also in dictating the effectiveness of radiative damping. We also find the radiative damping timescales, the energy injection rate, and the spacing of deep jets to be important. We combine these findings into our best‐guess simulations of the real Jupiter and find that low latitudes are relatively uncoupled between the layers, with high latitudes being more tightly coupled. These effects can be tied to the smallness of Jupiter's LD and the effectiveness of radiative damping as a coupling mechanism. These simulations do, however, produce equatorial subrotation and eddy‐momentum fluxes unlike those on the real planet. It may be, therefore, that spatially varying forcing and very long radiative damping timescales are required for this model to be more Jupiter‐like. [ABSTRACT FROM AUTHOR]

The exploration of high production, natural gas wells (>106 m3/d) has been extremely successful in the Gaoshiti and Moxi areas of the Leshan–Longnvsi paleo‐uplift, in the west‐central Sichuan Basin. This paper focuses on the Sinian and Cambrian reservoirs from the Gaoshiti and Moxi areas, where a dataset of new trace elements in bitumen and potential source rock is reported and where hydrocarbon‐source correlation is attempted based on trace elements characteristics of the 12 potential source rocks and 22 bitumen samples. Results show that the bitumen from the three reservoirs can be distinguished from each other using trace element distribution patterns and redox‐ and provenance‐sensitive elemental ratios. Bitumen in the second and fourth members of the Sinian Dengying Formation were derived primarily from the third member of the source rocks of the Dengying Formation, which represents a self‐sourced paleo‐petroleum system. In contrast, bitumen in the reservoirs of the Cambrian Longwangmiao Formation is derived from the Cambrian Qiongzhusi Formation and third member of Dengying Formation. The trace element method used in this study improves our understanding of the complex hydrocarbon–source relation and confirm the potential target for petroleum exploration in the study area. [ABSTRACT FROM AUTHOR]

SW Iran and the adjacent offshore are prolific petroleum‐producing areas with very large proven oil and gas reserves and the potential for significant new discoveries. Most of the oil and gas so far discovered is present in carbonate reservoir rocks in the Dehram, Khami and Bangestan Groups and the Asmari Formation, with smaller volumes in the Dashtak, Neyriz, Najmeh, Gurpi, Pabdeh, Jahrum, Shahbazan, Razak and Mishan (Guri Member) Formations. The Permo‐Triassic Dehram Group carbonates produce non‐associated gas and condensate in Fars Province and the nearby offshore. The Jurassic – Lower Cretaceous Khami Group carbonates are an important producing reservoir at a number of offshore fields and in the southern Dezful Embayment, and are prospective for future exploration. Much of Iran's crude oil is produced from the Oligo‐Miocene Asmari Formation and the mid‐Cretaceous Sarvak Formation of the Bangestan Group in the Dezful Embayment. This review paper is based on data from 115 reservoir units at 60 oil‐ and gasfields in SW Iran and the adjacent offshore. It demonstrates that the main carbonate reservoir units vary from one‐another significantly, depending on the particular sedimentary and diagenetic history. Ooidal‐grainstones and rudist‐ and Lithocodium‐bearing carbonate facies form the most important reservoir facies, and producing units are commonly dolomitised, karstified and fractured. In general, reservoir rocks in the study area can be classified into six major types: grainstones; reefal carbonates; karstified, dolomitised and fractured carbonates; and sandstones. The stratigraphic distribution of these reservoir rocks was principally controlled by the palaeoclimatic conditions existing at the time of deposition. A comparative reservoir analysis based on core data shows that dolomitised and/or fractured, grain‐dominated carbonates in the Dehram Group, Lower Khami Group and Asmari Formation typically have better reservoir qualities than the Cretaceous limestones in the Upper Khami and Bangestan Groups. [ABSTRACT FROM AUTHOR]

How deep do Saturn's zonal winds penetrate below the cloud level has been a decades‐long question, with important implications not only for the atmospheric dynamics but also for the interior density structure, composition, magnetic field, and core mass. The Cassini Grand Finale gravity experiment enables answering this question for the first time, with the premise that the planet's gravity harmonics are affected not only by the rigid body density structure but also by its flow field. Using a wide range of rigid body interior models and an adjoint based optimization for the flow field using thermal wind balance, we calculate the flow structure below the cloud level and its depth. We find that with a wind profile, largely consistent with the observed winds, when extended to a depth of around 8,800 km, all the gravity harmonics measured by Cassini are explained. This solution is in agreement with considerations of angular momentum conservation and is consistent with magnetohydrodynamics constraints. Plain Language Summary: Observations show strong east‐west flows at the cloud level of Saturn. These winds are strongest at the equatorial regions, reaching up to 400 m/s, about 4 times stronger than tornado strength winds on Earth. Yet until now we had no knowledge on how deep these winds penetrate into the interior of the gas giant. The gravity experiment executed during the Grand Finale stage (May–August 2017) of the NASA Cassini mission helps answering this question. It is well established that any large‐scale motion of the fluid would have a signature in the density distribution and therefore in the planet gravity field. If we can estimate the internal structure and shape of the planet, we might be able to decipher the depth of the winds from its signal in the gravity measurements. Moreover, the rigid‐body and flow contribution to gravity field are entangled together, therefore it is necessary to use a wide range of rigid‐body models in order to define the wind‐induced gravity signal. In this work we propose a solution to the problem. We find that the gravity measurements can be explained with a flow pattern, similar to that observed at the cloud level, penetrating to depths of more than 8,000 km into the planet interior. This has important implications not only for the atmospheric dynamics but also for the interior density structure, composition, magnetic field, and core mass. Key Points: Cassini gravity measurements point to deep differential flows within SaturnUsing a wide range of rigid body internal structure models, the required wind‐induced gravity signal is definedWith a conservatively modified cloud‐level wind and an optimized vertical profile, extended to a depth of 8,800km, all gravity measurements are explained [ABSTRACT FROM AUTHOR]

The climate on Earth is generally determined by the amount and distribution of incoming solar radiation, which must be balanced in equilibrium by the emission of thermal radiation from the surface and atmosphere. The precise routes by which incoming energy is transferred from the surface and within the atmosphere and back out to space, however, are important features that characterize the current climate. This has been analyzed in the past by several groups over the years, based on combinations of numerical model simulations and direct observations of the Earth's climate system. The results are often presented in schematic form to show the main routes for the transfer of energy into, out of and within the climate system. Although relatively simple in concept, such diagrams convey a great deal of information about the climate system in a compact form. Such an approach has not so far been widely adopted in any systematic way for other planets of the Solar System, let alone beyond, although quite detailed climate models of several planets are now available, constrained by many new observations and measurements. Here we present an analysis of the global transfers of energy within the climate systems of a range of planets within the Solar System, including Mars, Titan, Venus and Jupiter, as modelled by relatively comprehensive radiative transfer and (in some cases) numerical circulation models. These results are presented in schematic form for comparison with the classical global energy budget analyses for the Earth, highlighting important similarities and differences. We also take the first steps towards extending this approach to other Solar System and extrasolar planets, including Mars, Venus, Titan, Jupiter and the 'hot Jupiter' exoplanet HD189733b, presenting a synthesis of both previously published and new calculations for all of these planets. [ABSTRACT FROM AUTHOR]

To understand the evolution of planetary systems, it is important to investigate planets in highly evolved stellar systems, and to explore the implications of their observed properties with respect to potential formation scenarios. Observations suggest the presence of giant planets in post-common-envelope binaries (PCEBs). A particularly well-studied system with planetary masses of 1.7 MJ and 7.0 MJ is NN Ser. We show here that a pure first-generation scenario where the planets form before the common envelope (CE) phase and the orbits evolve due to the changes in the gravitational potential is inconsistent with the current data. We propose a second-generation scenario where the planets are formed from the material that is ejected during the CE, which may naturally explain the observed planetary masses. In addition, hybrid scenarios where the planets form before the CE and evolve due to the accretion of the ejected gas appear as a realistic possibility [ABSTRACT FROM AUTHOR]

Introduction: The collisional history of the solar system provides important constraints on its dynamical and architectural evolution. Episodes of widespread enhancement in impactor flux reflect dynamical instabilities, which, in turn, are thought to be excited by giant planet migration events [e.g. 1,2]. While collisional histories constrained by the lunar and martian cratering record have been used to predict such an event at ~4.0 Ga [2], more recent dynamical models limit the timeframe of giant planet instabilities to within the first ~100 Ma of solar system history [3]. These earlier timescales are corroborated by the radiometric cooling ages of asteroidal meteorites. Since temperature-sensitive thermochronometric systems of meteorites would record the thermal imprint of an enhancement in highly ener - getic impact events, the apparent absence of widespread resetting of high-temperature thermochronometers contradicts an asteroid-belt-scale instability after 4.48 Ga [4]. We expand on these studies and aim to precisely constrain the timescales of widespread excitement in the asteroid belt within the first several hundred million years of solar system history. The challenge to resolving impact resetting of thermochronologic systems over this timescale is that it overlaps with the primary cooling of radiogenically heated parent planetesimals [e.g. 5]. To overcome this challenge, we implement a Bayesian statistical model to resolve these two processes through comparison of model asteroidal thermal histories to a database of chondrite 40Ar-39Ar dates [adapted from 4]. The 40K-40Ar system (as measured by the 40Ar-39Ar method) is particularly well suited to dating impact events given its sensitivity to resetting at moderate temperatures (<700 K). Methods & Approach: We developed a simple asteroid-scale thermochronologic evolution code, which simulates conductive cooling of a radiogenically heated spherical body [e.g. 5] and near-surface reheating by impacts. Model 40Ar-39Ar dates at different depths in the body are calculated from the time of cooling below a closure temperature. Impact resetting of the 40K-40Ar system is modeled by an exponentially decaying probabilistic impactor flux, for which each "collision" resets the cooling age of an assumed near-surface volume of the model asteroid. The thermal code is coupled to a Markov chain Monte Carlo inversion that stochastically varies model parameters (e.g. 40Ar closure temperature, onset of heightened impact flux) and for each perturbation calculates the likelihood that the observed 40Ar-39Ar date distribution is drawn from the age distribution of the thermal model output. This inversion, via the Metropolis algorithm, explores the likelihood space corresponding to the above-mentioned model parameters and converges on a distribution that describes the posterior estimate for the value of each parameter, as constrained by the observed 40Ar-39Ar date distribution. Preliminary Results & Discussion: We report two key observations from preliminary results. (1.) Thermal simulations that do not incorporate impact resetting fail to converge on model parameters that reproduce the observed distribution of >4 Ga 40Ar-39Ar dates in chondrites. This indicates that unperturbed conductive cooling alone cannot account for the observed cooling ages. (2.) In contrast, when the simulation incorporates a single bombardment event characterized by an exponential decay in impactors from a peak initial flux, the posterior converges on a mean instability start date of 113 ± 53 Ma (1s) with local maxima in the posterior distribution at ~60 Ma, 100-130 Ma, and ~190 Ma. These distinct peaks represent higher likelihood regions of the parameter space and may imply multiple instabilities recorded in the chondritic 40Ar-39Ar date record. Limitations & Future Work: We acknowledge several oversimplifications used in the current asteroid thermal codes, including assumptions of (1.) a single bombardment event and (2.) quantitative representation of all original asteroidal material in the meteorite record. We will explore and present on the effects of incorporating multiple bombardment events and differential preservation/delivery of asteroidal material, among other assumptions and model sensitivities, on the posterior estimates of when elevated impactor fluxes occurred in the young asteroid belt. [ABSTRACT FROM AUTHOR]

Introduction: The formation of chondrules, the enigmatic igneous mm-sized spherules found in chondrites, is critical to understanding the dynamics of our early solar system and the formation of planetary systems in general. Recent modeling work has determined that impact jetting during accretionary impacts may be a viable mechanism for producing chondrules [1], even in the outer solar system where planetesimals are expected to have been composed of ice-rock mixtures [2]. Impact jetting occurs during the first moments of contact between impacting bodies and requires very high resolution to model. For vertical impacts between rocky bodies, a chondrule mass ~1% of the impactor mass may be formed by jetting. This number decreases with the addition of ice to the bulk composition of impacting bodies (e.g., for bodies composed of dunite mixed with 30% ice by mass, a chondrule mass ~0.001% of the impactor mass may be generated). An estimate of cumulative chondrule mass produced by impact jetting during planetary accretion in the inner solar system has been presented in [1] by evaluating chondrules formed in each impact that occurs during GAME simulations of terrestrial planet accretion. The models for accretion of giant planets in the outer solar system differ significantly from standard planetesimal accretion models that describe terrestrial planet formation. Namely, the accretion of giant planet cores of ~10 MÅ is more accurately described by pebble accretion models [e.g., 3]. In this work we synthesize results from pebble accretion models of giant planet core formation with impact models of ice-rock bodies in order to present an estimate of cumulative chondrule mass formed in the outer solar system. Methods: The iSALE2D shock physics code was used to perform simulations of impact jetting during collisions of bodies with mixed ice and rock compositions. In each iSALE model, a 10 km diameter projectile impacts a flat target at impact velocities ranging from 2-7 km/s, in increments of 0.5 km/s. The projectile and target match in composition for a given mixture of ice and dunite. The mass fraction of ice mixed with dunite ranges from 0-50% ice by mass, in increments of 10%. The mass of chondrule forming material is estimated by considering material that is at least partially molten (i.e., has a peak entropy greater than the incipient melting entropy of dunite, 2371 J/kg/K) and jetted above escape velocity. We calculate how the mass of chondrules changes based on escape velocity by considering ratios of impact velocity to escape velocity, or velocity fractions, from 0.5 to 3. The LIPAD code is used to simulate accretion of giant planet cores in the outer solar system and track all the collisions occurring. The initial conditions for this simulation match those presented in [3]. For each accretionary impact that occurs within the impact velocity range modeled in iSALE and velocity fraction range stated above, we interpolate an estimate of the mass of chondrules formed. By summing the mass of chondrules formed in each impact that occurs over time, we generate an estimate of the cumulative mass of chondrules formed by impact jetting during the accretion of giant planet cores in the outer solar system. Results and discussion: From initial results of giant planet core formation using LIPAD, we find that the mass of chondrules produced by impact jetting, assuming vertical impacts, ranges from 1020 to 1022 kg. The lower bound of this range corresponds to impacts between bodies that are 50% ice by mass, and the upper bound corresponds to impacts between pure dunite bodies. Our results indicate that despite the higher overall mass present in the outer solar system, the total mass of chondrules formed there during impact jetting may be comparable to the jetted chondrule mass produced in the inner solar system [1]. This may be consistent with the lower fraction of chondrules observed in many carbonaceous chondrites [4]. The mass of chondrules produced by impacts in the outer solar system is quite sensitive to when the transition to pebble accretion occurs. In this simulation, the rate of chondrule formation drops off around 0.5 Myr when bodies become large enough for efficient pebble accretion to dominate. These large bodies continue to accrete other bodies, but the impact velocities exceed 7 km/s and we cannot currently consider these high velocity impacts in our calculations of chondrule mass. Although our results are preliminary, this work could help to shed light on the dynamics of accretion of the giant planets. In addition, the iSALE simulations of impact jetting were all vertical impacts, while we expect more realistically occurring oblique impacts to produce larger quantities of chondrule material [5] which could increase chondrule abundances by a few times. Acknowledgements: This work was supported by grant 80NSSC20K0422 from the NASA, USA Emerging Worlds program. [ABSTRACT FROM AUTHOR]

Introduction: The JAXA's asteroid explorer Hayabusa2 investigated Cb-type near-Earth asteroid (162173) Ryugu from June 2018 to November 2019 [e.g., 1-3], during which the spacecraft made two touchdown operations onto the asteroid surface for sample collection with projectile shooting [4-8]. The spacecraft returned its reentry capsule to the Earth on December 6, 2020 [8, 9]. The mass of the returned samples was ~5 grams in total; ~3 grams from the first touchdown site and ~2 grams from the second touchdown site [9]. At Institute of Space and Astronautical Science (ISAS), JAXA, particles larger than ~1 mm in size were individually photographed, weighed, and investigated spectroscopically inside the nitrogen-filled chamber system. Particles < 1mm were inspected in a sample dish as bulk aggregates. The initial characterization phase of the returned sample shows that it well represents the finding from spacecraft investigation of the asteroid surface [8-10]. Initial Analysis: After the first six-month of initial description at ISAS, ~300 mg of returned samples (~6 % of total mass) were allocated to the Hayabusa2 initial analysis team in June 2021 for one-year priority analysis led by the Hayabusa2 mission [11]. The number of allocated particles larger than 1 mm were 11 from the first touchdown site (Chamber A grains) and 11 from the second touchdown site (Chamber C grains). Ten sets of aggregate samples, consisting of particles smaller than 1 mm, were also allocated (5 from Chamber A and 5 from Chamber C). To characterize the Ryugu sample and to maximize the science output of the Hayabusa2 mission, the initial analysis team consisted of six sub-teams: Chemistry [12], Mineralogy and Petrology for coarse grains [13], Mineralogy and Petrology for fine grains [14], Volatiles [15], Macromolecular Organics [16], and Soluble Organic Matter [17]. The overall analysis activity went smoothly thanks to the dedication and hard work of the team in spite of challenges presented by a lack of in-person communication during the COVID-19 pandemic. What is Ryugu? All the results from the initial analysis are interpreted to support the hypothesis that Ryugu comes from a parent body of the most chemically primitive CI chondrites (least fractionated from the Sun's elemental abundance) [12-17]. Ryugu's volatile and organic contents are highest compared to the meteorites in our collections except for micrometeorites and interplanetary dust particles [15-17]. Because C-type asteroids are a major group of asteroids, the close relation of Ryugu to the rarest type of chondrites (CI) suggests that the Earth's atmosphere works an effective filter for the influx of fragile meteorites, resulting in a biased sampling of meteorites on the ground. A notable mineralogical difference of Ryugu samples from CI chondrites [12-14] indicates that all CI chondrites recovered on Earth experienced significant terrestrial weathering since their fall. The Hayabusa spacecraft retuned surface particles from S-type asteroid (25143) Itokawa in 2010, which was found to be a parent body of equilibrated LL ordinary chondrites [18, 19]. Therefore S-type asteroids and C-type asteroids are likely to be composed of the non-carbonaceous (NC) and carbonaceous chondrite (CC) group materials, representing isotopically dichotomous components in the early Solar System [20]. Coexistence of S- and C-type asteroids in the present main belt thus requires small body migration in the (early) Solar System, likely caused by migration of giant planets [21]. Comparison of Ryugu samples with the sample from B-type asteroid (101955) Bennu [22] will further constrain the dynamical and chemical evolution of small bodies and the (early) Solar System. [ABSTRACT FROM AUTHOR]

Introduction: The formation and migration of giant gas planets are crucial to the evolution of planetary systems, and yet the timing of these events in our Solar System remains largely unconstrained. Angrite meteorites represent some of the oldest materials in the inner Solar System, and therefore provide an exclusive window into the history of the early Solar System [1]. Recent oxygen isotopic analyses have redefined the angrite fractionation line (AFL) to Δ17O = 0.064 ± 0.018‰ (2s) and highlighted that the quenched angrite NWA 12320 exhibits an anomalous Δ17O value of -0.017 ± 0.004‰ (2s) [2]. Mineralogically, NWA 12320 is comparable to the majority of quenched angrites, however, it lacks the usual abundance of olivine xenocrysts. Here we present evidence for an oxygen isotopic disequilibrium between the matrix and olivine xenocrysts in three quenched angrites, NWA 12320, Asuka-12209 and Asuka-881371, discussing the possible causes of this variation. Matrials and Methods: Olivine xenocrysts in the three quenched angrites were separated from the matrix and subsequent O-isotope data of both matrix and olivine fractions were obtained at the Open University using laserassisted fluorination following established procedures [3,4]. Results: The olivine xenocrysts of NWA 12320, Asuka 12209 and Asuka 881371 display Δ17O values of - 0.065 ± 0.018‰, -0.068 ± 0.015‰ and -0.067 ± 0.008‰, respectively, indistinguishable from whole-rock angrite meteorites measured in other studies [2]. Intriguingly, the matrix fractions of all three samples reveal less negative values that are statistically distinct from the other angrite meteorites (Δ17O = -0.024 ± 0.016‰, -0.001 ± 0.007‰ and -0.003 ± 0.007‰, respectively). While lesser amounts of matrix may result in undetectable shifts in some quenched angrites, NWA 12320 is dominated by matrix and therefore the whole-rock sample equates to a matrix separate. Electron backscatter diffraction on the olivine xenocrysts in NWA 12320 revealed granular textures. The granular olivine xenocrysts have no discernible preferred orientation and are cemented by olivine with a higher Fe content, with neighbouring grains displaying vastly distinct orientations, indicative of recrystallization, after shockinduced mosaicism or fragmentation. Discussion: The granular textures within NWA 12320, have also been reported in the urelite JaH 422 and the howardite JaH 556 [5,6]. These meteorites have been interpreted as impact-melt rocks with the olivine grains representing unmolten relics of their precursor material. Interestingly, JaH 556 similarly displayed slight oxygen isotopic differences between the bulk-rock and matrix fractions. This textural evidence could suggest that at least some olivine grains in NWA 12320 remained as relict material and were affected by high temperature processes on the angrite parent body (APB). We therefore favor the hypothesis that NWA 12320, Asuka 12209 and Asuka 881371 have an impact-melt origin, with the matrix representing recrystallized material induced by an impact event and the olivine grains representing relict material of the original APB. The impactor is unlikely to be a carbonaceous chondrite based on the positive Δ17O values of the matrix, nor an ordinary chondrite due to the lack of metal within angrite meteorites. We therefore propose that the impactor was an unsampled achondrite like NWA 11042 [7]. We conclude that this extreme dynamical excitement resulting in early, large scale mixing, is not an expected result of the classical accretion of bodies, and demands the interference of the giant gas planets. Summary: We interpret our findings in terms of quenched angrite meteorites representing impact-melt rocks rather than shallow magmatic intrusions, recording evidence of impact-driven mixing. This mixing may have taken place in response to the inward migration of giant planets (as envisaged in the Grand Tack model [8]) and hence would represent the earliest isotopic evidence for planetary migration in the early Solar System. [ABSTRACT FROM AUTHOR]