bluuebunny/crossref_metadata_2025 huggingface dataset:
Ariel - The ESA M4 Space Mission to Focus on the Nature Of Exoplanets
Authors: Lueftinger Theresa , Tinetti Giovanna , Salvignol Jean-Christophe , Eccleston Paul
Published: July 2024

The ESA M4 mission Ariel, the atmospheric remote-sensing infrared exoplanet large-survey, has been adopted in 2020 within the Cosmic Vision science programme of ESA. The goal of Ariel is to investigate the atmospheres of planets orbiting distant stars in order to address the fundamental questions on how planetary systems form and evolve and to study in detail the composition of exoplanetary atmospheres. During its 4-year mission, Ariel will observe up to 1000 exoplanets -  building on (future) findings from space missions like PLATO, JWST, TESS, and CHEOPS - ranging from Jupiter- and Neptune-size down to super-Earth size, in a wide variety of environments, in the visible and the infrared. The main focus of the mission will be on warm and hot planets in orbits close to their star. Some of the planets may be in the habitable zones of their stars, however. The analysis of Ariel spectra and photometric data will allow to extract the chemical fingerprints of gases and condensates in the planets’ atmospheres, including the elemental composition for the most favourable targets. The Ariel mission has been developed by a consortium of more than 60 institutes from 15 ESA member state countries, including UK, France, Italy, Poland, Spain, the Netherlands, Belgium, Austria, Denmark, Ireland, Hungary, Sweden, Czech Republic, Germany, Portugal, with an additional contribution from NASA and CSA. 
The evolution of Jupiter and Saturn with helium rain
Authors: Howard Saburo , Müller Simon , Helled Ravit
Published: July 2024

Studying the interiors of giant planets is important for understanding their origin. While accurate measurements of gravity field and seismology from Juno and Cassini teach us about the present-day internal structures of Jupiter and Saturn, further insights can be gained from simulating their evolution. Understanding the long-term thermal evolution of the giant planets is also critical to connect the planetary formation and the current-state structure of planets.In Jupiter and Saturn, a phase separation between hydrogen and helium occurs, resulting in the formation of helium droplets which settle towards the deep interior. This phenomenon, also known as helium rain, can strongly affect their thermal evolution. Therefore, studying the evolution of Jupiter and Saturn, and giant planets in general, requires a good comprehension of the phase diagram of hydrogen and helium. However, the latter remains uncertain given the discrepancy between various theoretical calculations and experimental data.I will present results of evolution models of Jupiter and Saturn with helium rain, using different phase diagrams. We find that a consistency between Jupiter's evolution and the Galileo measurement of its atmospheric helium abundance is achieved only if a shift in temperature in the existing phase diagrams is applied. We next use the shifted phase diagrams to model Saturn's evolution and find consistent solutions for both planets. We confirm that demixing in Jupiter is modest while in Saturn, the process of helium rain is significant. I will discuss the inferred structure of both planets, the inferred atmospheric helium content in Saturn and show the importance of equations of state and atmospheric models on evolution models. This analysis reveals key information on the interiors of giant planets and can also be used to constrain the phase diagram of hydrogen and helium.
Analysis of photocentre offset from Gaia astrometry on selected asteroids and planetary satellites
Authors: Liu Ziyu , Bartczak Przemyslaw , Hestroffer Daniel , Oszkiewicz Dagmara , Desmars Josselin , David Pedro , Lainey Valery , Kryszczyńska Agnieszka , Dziadura Karolina
Published: July 2024

The Gaia space mission provides highly precise astrometric data  about 160,000 solar system objects. Because the object is extended and Gaia observes at a non-zero solar phase angle, the measurement is subject to a photocentre-barycentre shift effect. In other words, astrometry records the centre of the illuminated part (photocentre) of the celestial body instead of the actual centre of mass. This displacement is determined by the surface properties, size, spin and shape of the target [1]. The effect can be shown by statistically significant residuals after the fitting of heliocentric or planetocentric orbits using Gaia astrometric data. The typical magnitude of the offsets for the largest bodies (with diameters > 100km) is of a few mill-arcseconds, larger than the Gaia precision.  In this work, we used two approaches to correct the effect. The first is to assume that the body is a sphere and use an analytical formula to estimate the offset [2], which is a valid approximation for dwarf planets or planetary satellites. Secondly, we directly used the simulated displacement from a complex shape model by reconstructing the Gaia-object-Sun geometry at the observation epoch. This is done by using an updated spin and shape topographic model derived from photometric data (including Gaia DR3 photometry) using the Sage method [3,4].  In the presentation, we will show the effect of the photocentre correction using both methods on a selection of large asteroids and Jovian satellites.  [1] L. Lindegren, “Meridian observations of planets with a photoelectric multislit micrometer.,”, vol. 57, no. 1-2, pp. 55–72, May 1977[2] D. Hestroffer, “Photocentre displacement of minor planets: analysis of HIPPARCOS astrometry,”, vol. 336, pp. 776–781, Aug. 1998.[3] P. Bartczak and G. Dudziński, “Shaping asteroid models using genetic evolution (SAGE),”, vol. 473, no. 4, pp. 5050–5065, Feb. 2018. doi: 10.1093/mnras/stx2535. arXiv: 1904.08940 [astro-ph.EP].[4] P. Bartczak et al, “Synergy between SAGE and SHAPE algorithms for modelling the physical parameters of asteroids,”  in European Planetary Science Congress, Sep. 2024, EPSC2024.
Atmospheric compositional variations due to changes in mantle redox state 
Authors: Brachmann Caroline , Noack Lena , Sohl Frank , Gaillard Fabrice
Published: July 2024

Rocky exoplanets' internal constitution is inferred indirectly through their atmospheric composition. Confidence in this inference necessitates coupling interior and atmospheric models. In the past, various atmospheric redistribution models were developed to determine the composition of exoplanetary atmospheres by varying element abundance, temperature and pressure (Woitke et al., 2021).However, these models neglect that present-day atmospheres were formed via volcanic degassing and, consequently, element abundances are limited by thermodynamic processes accompanying magma ascent and volatile release. Here we combine volcanic outgassing with an atmospheric chemistry model to simulate the evolution of C-H-O-N-S atmospheres in thermal equilibrium below 600 K. These volatiles can be stored in significant amounts in basaltic magmas and are the most commonly degassed species.Our model calculates possible atmospheric compositions by varying oxygen fugacity, melt and surface temperature, and volatile abundances, considering phase solubility, atmospheric processes (e.g., water condensation, hydrogen escape), the change in redox conditions caused by volcanic activity and the influence of existing atmospheres on further degassing.Our findings indicate that the prevailing atmospheric type below 600 K typically consists of CO2, N2, CH4, and, depending on temperature, H2O. Moreover, we illustrate that evolving atmospheric pressure and composition hinge significantly on the oxygen fugacity of the melt due to its impact on gas speciation and solubility. Reduced conditions yield atmospheres dominated by H2, NH3, CH4, and H2O, with exceedingly low atmospheric pressures. In contrast, oxidized conditions result in atmospheres comprising H2O, CO2, N2, and limited CH4, accompanied by high atmospheric pressures. Sulfur gases emerge predominantly at higher surface temperatures, manifesting as S2 or H2S under low mantle redox states and as SO2 under high mantle redox states. Notably, O2 is not generated abiotically, as sufficient carbon or hydrogen remains available to form H2O, CO, or CO2. Therefore, the formation of O2-dominated atmospheres would require excessive photodissociation of H2O or CO2 (Chang et al., 2021), a phenomenon likely common on planets orbiting M-dwarf stars.In addition to highlighting the indirect inference of rocky exoplanets' internal constitution through their atmospheric composition, we demonstrate that reduced magmas can oxidize via H2 and CO degassing, whereas oxidized magmas may undergo reduction through SO2 degassing. Furthermore, we conclude that the depth of the magma source region and the planetary size significantly influence atmospheric compositions due to the varying pressure dependence of degassed species' solubilities.
The TRANSient NEO population: asteroids, comets… or none of the above?
Authors: Ieva Simone , Ishiguro Masateru , Perna Davide , Dotto Elisabetta , Mazzotta Epifani Elena , Petropoulou Vasiliki , Deshapriya J. D. Prasanna , Hasselmann Pedro H. , Bourdelle de Micas Jules , Bach Yonsoo P. , Jin Sunho
Published: July 2024

The classical distinction between asteroids (rocky and inert), and comets (ice-rich and active) has been blended in the last 15 years, leading to a more nuanced picture. Both classes are now believed to be simply end-members of a physical and dynamical continuum. The study of TRANSient NEOs (Near-Earth Objects showing characteristics of both classes) could be the missing link to understanding this new paradigm of small bodies continuum. We decided to investigate the TRANSNEO population because i) their repeated passages around the Sun make it in principle easier to detect a potential activity; ii) they can be extremely accessible for observations and a future space mission; iii) activity on NEO surfaces has been recently discovered even on apparently inactive places, thus attracting the interest of various space agencies. One of these intriguing bodies (3200 Phaethon) will indeed be the target of the JAXA DESTINY+ space mission, scheduled to be launched in 2025.  In 2022, we started a new project called “TRANSNEO” financed by the Italian National Institute for Astrophysics (INAF) to characterize via spectroscopy, photometry, and polarimetry these bodies that often both show the asteroid/comet designation. We will present the latest results of the TRANSNEO project and put it in the larger context of active bodies in the Solar System. Acknowledgments: This research was funded by the Italian National Astrophysical Institute (INAF) - Call for Fundamental Research 2022. E.D. acknowledges the support from the ASI (ASI-INAF agreement AC n. 2022-1-HH.0).
Pellet-grown chemical gardens in horizontal planar confined geometry : Diffusion-controlled growth and osmotic fracture
Authors: Zheng Mingchuan , Cardoso Silvana S. S. , Huppert Herbert E. , Cartwright Julyan H. E. , Routh Alexander F.
Published: July 2024

Chemical gardens refer to a class of plant-like self-assembling inorganic precipitate structures whose growth is driven by osmosis. They are thought to be related to hydrothermal vents and the origin of life. In this work, we have investigated the dynamical behaviour of chemical gardens grown in a horizontal Hele-Shaw cell from cobalt and manganese chloride with aqueous sodium silicate. It is found that the growth of the chemical gardens is well-described by a diffusion-controlled model. In reproducible time scales, the chemical gardens exhibit explosive fracture, which we attribute to osmosis-induced pressurisation. This is similar to osmotic lysis found in biological cells.
The high-resolution structure of debris disks revealed by the ARKS ALMA program
Authors: Han Yinuo ,   ARKS Team
Published: July 2024

High-resolution surveys with ALMA have revealed that substructures such as rings and gaps are common in protoplanetary disks, however it is not clear whether this is also true for debris disks due to their lower surface brightness and therefore the tendency for observations to be obtained at lower resolution with ALMA. Lower resolution observations do not commonly reveal systems of rings with radial gaps in debris disks, but the handful of high-resolution debris disk images with ALMA do resolve radial gaps in most, however this sample of only a few systems is insufficient to draw strong conclusions. Recently, the ALMA survey to Resolve exoKuiper belt Substructures (ARKS) was carried out to understand the high resolution structure of 18 debris disks. The sample spans a range of inclinations, allowing us to study both the radial and vertical structure in debris disks in detail. With an increasing volume of theoretical work exploring the signatures of planets imprinted on disks, understanding the high-resolution disk structure is important both for testing planet formation models and for constraining planetary system architecture. In this talk, we will present observations from the ARKS program and discuss ongoing modelling efforts, focusing particularly on the radial structure and non-parametric modelling approaches. We will discuss the prevalence of radial substructures in debris disks, present ongoing analyses on any correlations between disk features and outline some of the implications of the findings on planetary dynamics in these systems.
Numerical Model of Reduction of Apparent Thermal Inertia by Interrupted Vertical Heat-Flow
Authors: Hamm Maximilian , Strauß Moritz , Biele Jens , Luther Robert , Knollenberg Jörg , Grott Matthias
Published: July 2024

Introduction: The JAXA Hayabusa2 sample return mission investigated asteroid (162173) Ryugu via remote sensing (Tsuda et al., 2013, Watanabe et al., 2019), deployed the DLR/CNES MASCOT (Ho et al., 2021), performed an artificial impact experiment (Arakawa et al., 2020) and returned samples to Earth (Yada et al., 2022). Ryugu is a rubble-pile asteroid with similarities to aqueously altered carbonaceous chondrites, in particular CI chondrites (Kitazato et al., 2021, Hamm et al., 2022, Nakamura et al. 2022, Yokoyama et al., 2022). One of the biggest surprises was the prevalence of boulders and dm-sized pebbles on the surface and the deficiency of smaller particles (Jaumann et al., 2019, Sugita et al., 2019). Such finer particles were expected to dominate the surface based on thermal inertia estimates from telescopic infrared observations (Müller et al., 2011). The MASCOT radiometer MARA and the main spacecraft’s TIR infrared imager confirmed the thermal inertia estimates from telescopic observations despite the boulder-dominated surface (Grott et al., 2019, Okada et al., 2020). The low thermal inertia was confirmed to be an intrinsic property of the boulders themselves (Grott et al., 2019, Hamm et al., 2020, Sakatani et al., 2021, Hamm et al., 2022). More specifically, the presence of a layer of dust masking the thermophysical properties of the boulder was limited to small patches of thin dust layers, or no dust at all (Biele et al., 2019, Hamm et al., 2023). In contrast to these in-situ results, the analysis of sample fragments by lock-in thermography resulted in a much higher thermal inertia more comparable to that of meteorites samples (Ishizaki et al., 2023). In this study we attempt to reconciliate the results from spacecraft observations and laboratory analysis by expanding our thermophysical mode to incorporate horizontal fractures. This procedure has been proposed by Elder et al., 2022. We investigate if it is possible to explain the MARA observations with a fracture boulder of higher bulk thermal inertia. This work has implication on the regolith gardening on asteroids like Ryugu as weak and porous boulders would respond to impacts of micro-meteorites differently than fracture boulders with low porosity (Cambioni et al., 2021).Methods: We start from the 1D-thermal model as used in Hamm et al., 2020. The heat conduction equation is solved for a 1D grid of N points from x0 = 0 to xN  . At the lower boundary condition, the flux is set to zero. The upper boundary condition is given by the energy balance. Illumination is calculated by averaging over those DEM-facets of the boulder shape model within the MARA field of view.  The emissivity of the surface reduced by thermal reradiation as described in Hamm et al., 2023. Here we modify the model such that the heat conduction equation is given by:ρcp ∂T/∂t = σ(T4(xd,t)- T4(xu,t))For xu
Observations of the JUICE PEP JEI plasma spectrometer during the Moon and Earth flyby in August 2024
Authors: Fränz Markus , Bambach Patrick , Fischer Henning , Krupp Norbert , Roussos Elias , Labudda Robert , Wittmann Philipp , Barabash Stas
Published: July 2024

The plasma spectrometer JEI is an ion and electron spectrometer designed to observe the thermal and medium energy charged particle environement  of Jupiter. It is part of the PEP instrument onboard JUICE. The flyby through the Earth-Moon system in August 2024 will be the first test of the instrument in a magnetospheric plasma and under higher radiation. We will report on the instrument performance and on observations of charged particles in the lunar environment and during the crossing of the Earth magnetosphere and radiation belts.
Pick-up ion distributions in the inner and middle Saturnian Magnetosphere
Authors: Radulescu Cristian , Coates Andrew , Simon Sven , Jones Geraint
Published: July 2024

Based on the entire dataset collected by the Cassini Plasma Spectrometer, we provide a comprehensive picture of the pitch angle and velocity distributions of pick-up ions (PUIs) in Saturn’s inner and middle magnetosphere. We investigate the dependence of these distributions on Saturnian Local Time and magnetic latitude. We also search for correlations to the signatures of ion cyclotron waves observed by the Cassini magnetometer. Our survey reveals that ion pitch angle distributions have a pancake shape and their full width increases monotonically with magnetic latitude. This increase in angular width is anti-correlated with the observed amplitudes of ion cyclotron waves that are generated during the thermalization of the PUI distribution. We find no evidence of the observed, non-monotonic change of wave amplitudes with magnetic latitude mapping into the width of the pitch angle distributions. This suggests that only a small fraction of the energy deposited into the waves is transferred back to the ions to broaden the distribution. A possible reason for this is wave damping by the Maxwellian core of the distribution, formed by ions that have already been incorporated into the sub-corotating flow. In addition, wave propagation away from the magnetospheric field direction could reduce the efficiency of the energy transfer. When moving away from Saturn’s magnetic equatorial plane, the observed half-width of the velocity distributions does not evolve appreciably with latitude and L shell value. This behavior changes only outside the orbit of Rhea where the observed velocity distributions begin to broaden due to elevated plasma temperatures.
Investigating the composition of  Halley-family comet 12P/Pons-Brooks with IRAM radio telescopes
Authors: Biver Nicolas , Boissier Jérémie , Bockelée-Morvan Dominique , Crovisier Jacques , Moreno Raphael , Cordiner Martin , Lis Dariusz C. , Roth Nathan , Bonev Boncho , Milam Stefanie , Drozdovskaya Maria , Opitom Cyrielle
Published: July 2024

Comet 12P/Pons-Brooks is a great Halley-family comet with an orbital period of71 years, that was first seen in 1385, and possibly earlier. It returnedto perihelion on 21 April 2024 at 0.78 au from the Sun (Fig.1)Its peak outgassing rate exceeded QH2O=1030 molec.s-1, with atotal visual magnitude of 4 in April and the comet was the focus of aworldwide observing campaign.We report observations of the comet with IRAM-30m and NOEMA facilitieson 20 January, 17, 20 March, and 22-28 April 2024. A frequency survey at3, 2 and 1 mm wavelengths, covering 8, 24 and 63 GHz respectively, was undertaken in Aprilunder average weather conditions.Several molecules and isotopologues were detected. We have derived expansionvelocity, gas temperature and production rates or upper limits on molecularabundances. Around perihelion we measured an expansion velocity around 1.1 km/sand a gas temperature of around 105 K.Lines of HCN, HNC, HC3N, CH3CN, HNCO, NH2CHO, CH3OH, H2CO, CO, HCO+, CS,H2S, OCS, SO, C34S and possibly (CH2OH)2 have been detected (Fig.2) and the molecularabundances will be presented. This is the most detailed chemicalinventory of a Halley-family comet obtained so far. The composition of 12Pwill be compared to previously investigated long- and short-periodcomets.Figure 1: Comet 12P/Pons-Brooks on 6.83 March 2024 UT. Visible image obtained with a 40.7-cm telescope, Field of view is 40x40 arcmin. (c) N. BiverFigure 2: Sample average spectra of lines observed with IRAM-30m in April 2024.The vertical scale in main beam brightness temperature (in K) is preliminary.Horizontal axis is Doppler velocity in the rest frame of the comet.Acknowledgements:This work is based on observations carried out under projects number W23AA001 and 066-23 with the IRAM NOEMA Interferometer and 30m telescopes.IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004). 
Constrained estimates of water loss from the martian atmosphere in a coupled TGO/MRO assimilation
Authors: Holmes James , Cangi Eryn , Chaffin Michael , Alday Juan , Olsen Kevin , Aoki Shohei , Liuzzi Giuliano , Villanueva Geronimo , Crismani Matteo , Fedorova Anna , Deighan Justin , Schneider Nicholas , Kass David , Lewis Stephen , Patel Manish , Vandaele Ann Carine , Korablev Oleg
Published: July 2024

The evolution of water on Mars is a major scientific topic that can in part be advanced through the provision of bounded constraints on the rates of water loss. The Mars Atmosphere and Volatile EvolutioN Imaging Ultraviolet Spectrograph instrument continues to monitor the Lyman alpha brightness from Mars that is intricately linked to the hydrogen escape flux, but converting the emission data to hydrogen escape fluxes is difficult. We provide a complementary approach by combining retrievals of water vapour, temperature and dust from multiple spacecraft in orbit around Mars through a process called data assimilation. Recent instrument data from the Nadir and Occultation for MArs Discovery (NOMAD) and Atmospheric Chemistry Suite (ACS) instruments on the ExoMars Trace Gas Orbiter (TGO) provide a relative wealth of water vapor vertical profiles that are critical in constraining the vertical distribution and transport of water, the main chemical species that influences hydrogen escape rates. This lower atmosphere assimilation, that forms part of the OpenMARS (Open access to Mars Assimilated Remote Soundings) dataset, is coupled to a state of the art upper atmosphere model. Number densities of key chemical species in the assimilation are passed as a lower boundary to the upper atmosphere model to drive calculations of hydrogen escape at 200 km altitude.We investigate the escape of hydrogen during the time period that covers the primary science phase of the ExoMars TGO mission until the end of Mars Year (MY) 35 (around 1.5 Mars years). Hydrogen escape during the perihelion season is found to be a factor of 10 increased compared to aphelion, as a result of the seasonal pump of water vapor from the southern polar cap twinned with increased levels of atmospheric dust. The general trend over the perihelion season is in line with the first-order fit of Hubble Space Telescope hydrogen escape fluxes, although larger temporal variations are evident in the model simulations as these can compute the hydrogen escape flux at much finer temporal resolution. Variations in the peak intensity of hydrogen escape flux in both MY are evident, with the global dust storm in MY34 creating an early dust season peak which seems to diminish the peak at perihelion found a year later. The southern summer regional-scale dust storms that occur each year create a late season peak in hydrogen escape flux, with year-to-year variability in the exact timing of this particular dust storm as leading to a shift in the timing of peak hydrogen escape.
Sublimation experiments to reproduce ammonium and chloride deposits under Cerean surface conditions
Authors: Haack David , Kaufmann Erika , Hagermann Axel
Published: July 2024

 IntroductionSublimation experiments performed in vacuum chambers have proven helpful for understanding the processes that occur on the surfaces of volatile-rich celestial bodies without significant atmospheres [1, 2, 3]. In a multitude of celestial bodies where water ice is not found today, there are indications that it was present in the past. On dwarf planet Ceres, located in the asteroid belt between Mars and Jupiter, indicators of what might have been liquid water are significant. In addition to hydrated minerals, salt deposits have been detected at the surface [4, 5], which is difficult to explain without the presence of water. These deposits can be interpreted as remnants of former saline ice reservoirs or ascending brines and may substantially alter the physical properties of the Cerean regolith [6, 7]. It is still in debate how salt-rich ice was transported to the surface of Ceres. Cryovolcanism or hydrothermal processes near the surface may be possible processes [8, 9]. Plausible heat sources for melting near-surface ice could be decaying radionuclides in the interior of Ceres or heat generation from impact events during Ceres' history. MethodsIn a vacuum sublimation chamber, environmental conditions similar to those on the Cerean surface are reproduced, and the conditions under which brines can form salt crusts on a regolith analogue are investigated. The focus is on the parameters of salt composition and the scenarios of how salty ice and regolith analogue interacted in a low-temperature and low-pressure environment. In particular, Na+, NH4+, Cl-, and CO32- based salts were used since they are observed in specific areas of the Cerean surface. We use two salt mixtures with different ratios of the selected ions and prepare three experimental setups:The Ceres regolith analogue is placed in a transparent sample container, saturated with brine, precooled to a solid sample at 190 K, and mounted in a sublimation chamber.
The regolith analogue is saturated with liquid brine and placed in the sample container without being precooled.
The dry regolith analogue is covered with a layer of salty ice particles
Formation of Uranus regular satellites: insights into planetary accretion and differentiation in spreading disks
Authors: Reynard Bruno , Sotin Christophe
Published: July 2024

Current models suggest the five regular moons of Uranus formed rapidly from a planetary disk after a giant impactor hit Uranus and caused its large spin axial tilt of ~98° (Ida et al., 2020; Woo et al., 2022). A power-law relationship between size and density of moons evidences varying rock/ice ratios in the moons. This relationship is not well described by differential diffusion of rock and ice in the disk (Woo et al., 2022). We find that this relationship is well explained by a mild enrichment of rock with respect to ice in the solids that aggregate to form the moons, following Rayleigh law for distillation (Rayleigh, 1896). In this model, moon composition and density reflect their order of formation in a closed-system circumplanetary disk. For Uranus, the largest and densest moons Titania and Oberon (R ~ 788 and 761 km, respectively) first formed, then the mid-sized Umbriel and Ariel (585 and 579 km), satellites in each pair forming simultaneously with similar composition, and finally the small rock-depleted Miranda (236 km). Fractionation of rock and ice during aggregation of planets and moons may occur in other planetary disks. Rayleigh distillation in the Saturnian disk may for instance account for early formation of rock-poor Rhea, Iapetus and Tethys. This mechanism adds to those affecting the composition of accreting planets and moons in disks such as temporal/spatial variation of disk composition due to differential diffusion, advection, and large impacts. Ida, S., Ueta, S., Sasaki, T., Ishizawa, Y., 2020. Uranian satellite formation by evolution of a water vapour disk generated by a giant impact. Nature Astronomy 4, 880-885.Rayleigh, L., 1896. L. Theoretical considerations respecting the separation of gases by diffusion and similar processes. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science 42, 493-498.Woo, J.M.Y., Reinhardt, C., Cilibrasi, M., Chau, A., Helled, R., Stadel, J., 2022. Did Uranus' regular moons form via a rocky giant impactor? Icarus 375, 114842. 
Interior Evolution of Magma Oceans Exoplanets
Authors: Sastre Mariana , Lichtenberg Tim , Nicholls Harrison , Bower Dan , Kamp Inga
Published: July 2024

The magma ocean (MO) phase typically describes the early stage of rocky planets, during which the entire planet is molten due to heat generated by accretion processes. In the case of short-period exoplanets inside the runaway greenhouse limit, this phase may last Gyrs, until the inventory of major greenhouse gasses, such as H2O and H2, is exhausted. The internal evolution of these planets is influenced by various factors, including the exchange of volatiles between the molten planetary interior and the atmosphere. This exchange significantly impacts planetary climate, exoplanet bulk densities, surface conditions , and long-term geodynamic activity by controlling greenhouse effects, surface water stability, and atmospheric composition. This research focuses on modeling this interaction under different redox conditions. Using a coupled computational framework of the planetary interior and atmosphere, we study the detailed evolution of the magma oceans phase, aiming to understand the crystallization sequence and the resulting internal structure of the planet. We investigate the impact of the cooling sequence and evolving climatic conditions on mantle differentiation, mineralogy, formation of crusts, and the consequent composition of the atmosphere.
A new model of the neutral gas torus of Europa
Authors: Nenon Quentin , Leblanc François
Published: July 2024

The neutral particles that escape the surface and exosphere of Europa populate a neutral gas torus around Jupiter. The detection and characterization of this neutral structure can not only shed light on the escape processes at work at Europa, but can also help to determine if Europa has a global influence on the Jovian plasma and magnetosphere.We will present a new Monte Carlo model of the Europa neutral gas torus developed in the frame of the FACOM project funded by ANR (French national agency for research). Neutral ionization rates in the Jovian magnetosphere are computed based on Voyager plasma densities and temperatures, including suprathermal electrons. The source rate of neutrals escaping Europa’s gravity is constrained with the three-dimensional Exosphere Global Model EGM [Oza, Leblanc, et al., 2019]. In particular, we will present the first simulations of the H2O water torus of Europa, with a source rate of H2O at Europa constrained with EGM.Finally, we will use our new model to reconsider the observability of the neutral torus in UV observations [Roth et al., 2023], energetic ion pitch angle distributions [Sarkango et al., 2023], ENA imaging [Smith et al., 2019], and pick-up ion observations [e.g. Szalay et al., 2022]. The impact of our results on future JUICE and Clipper observations of the Europa neutral gas torus will be presented.This research holds as part of the project FACOM (ANR-22-CE49-0005-01_ACT) and has benefited from a funding provided by l’Agence Nationale de la Recherche (ANR) under the Generic Call for Proposals 2022. References:Oza et al. 2019: 10.1016/j.pss.2019.01.006Roth et al. 2023: 10.3847/PSJ/accdddSarkango et al. 2023: 10.1029/2023GL104374Smith et al. 2019: 10.3847/1538-4357/aaed38Szalay et al. 2022: 10.1029/2022GL098111Smith, H. T., Mitchell, D. G., Johnson, R. E., Mauk, B. H., & Smith, J. E. (2019). Europa neutral torus confirmation and characterization based on observations and modeling. The Astrophysical Journal, 871(1), 69.
Atmospheric collapse and maintenance of habitable environment on tidally-locked exoplanets using a 3D-GCM
Authors: Taniguchi Keigo , Kodama Takanori , Turbet Martin , Chaverot Guillaume , Genda Hidenori
Published: July 2024

Habitable planets around M dwarfs are remarkable targets as they are among the least difficult terrestrial-size planets to detect and characterize. However, the climate characteristics on these planets are thought to be different from solar system terrestrial planets in particular because these planets are expected to be in a tidally-locked state, with a permanent irradiated hemisphere (dayside) and opposite one (nightside). If a planet orbits far from its host star, nightside temperatures can become extremely low, which leads volatile species such as CO2 and CH4 in the atmosphere to condense onto the surface. This phenomenon, known as atmospheric collapse, is thought to prevent habitable environment since removal from the atmosphere (especially CO2) decreases the stabilizing greenhouse effect.We investigated the relationship between atmospheric collapse and habitability using the Generic Planetary Climate Model (Generic PCM), a 3-D global climate model historically developed at the Laboratoire de Météorologie Dynamique (LMD), by changing stellar insolation and CO2 partial pressure. The onset of atmospheric collapse for each case is decided by the surface amount of condensed CO2. As a result, we found cases where locally habitable environment on the dayside remains during/after the atmospheric collapse event in spite of the decrease in greenhouse effect. This is because the decrease in atmospheric mass and thus in atmospheric pressure makes day-night atmospheric heat transport less efficient, resulting in less of energy by insolation on the dayside. In addition, lower background gas cases were more habitable (i.e., more likely to have surface liquid water) over a wide range of CO2 partial pressure. While high background gas pressure is usually considered to enhance the greenhouse effect due to pressure broadening, on tidally-locked planets less background gas contributes to an increase in dayside temperatures.To conclude, our results provide a new picture of the relationship between atmospheric collapse and habitability on tidally-locked, cool planets.
The Atmospheric Remote-sensing Infrared Exoplanet Large-survey sensitivity and performance
Authors: Pascale Enzo , Bocchieri Andrea , Eccleston Paul , Mugnai Lorenzo , Savini Giorgio , Tinetti Giovanna
Published: July 2024

The Ariel space mission will characterise spectroscopically the atmospheres of a large and diverse sample of hundreds of exoplanets. Targets will be chosen to cover a wide range of masses, densities, equilibrium temperatures and host stellar types to study the physical mechanisms behind the observed diversity in the population of known exoplanets. With a 1-m class telescope, Ariel will detect the atmospheric signatures from the small,
A Review of Image-based Small Planetary Body Shape Modelling
Authors: Chen Hao , Willner Konrad , Hu Xuanyu , Xiao Haifeng , Gläser Philipp , Oberst Jürgen
Published: July 2024

Images are a powerful data source for modelling the shape of small planetary bodies, e.g., asteroids, comets, and many planetary satellites. The traditional stereo-photogrammetry (SPG), stereo-photoclinometry (SPC) methods have recently been joined by Deep Learning (DL) methods to achieve shape modelling. SPG and SPC methods have been applied previously to support various exploration missions, such as NASA OSIRIS-REx mission (Palmer et al., 2022), ESA Rosetta mission (Preusker et al., 2015), JAXA Hayabusa and Hayabusa2 missions (Gaskell et al., 2008; Watanabe et al., 2019), etc. To effectively achieve accurate 3D reconstruction, SPG methods require images taken under similar illumination geometry, as well as sufficient viewing coverage from different perspectives, while SPC methods prefer images involving illumination conditions. Recently developed DL methods are divided into two modes. One of them involves using DL techniques to replace specific steps of the traditional methods in order to enhance shape modeling accuracy. For example, the matching process in the SPG method may be replaced by the DL technique to improve the matching accuracy (Chen et al., 2023). In contrast, the so-called “neural implicit methods” make full use of DL methods to replace the SPG method once accuracy in positions and orientations is attained (Chen et al., 2024). This approach can be trained and derive shape models end-to-end without any additional supporting work steps, showing a high potential as a complementary method for SPG and SPC. It is worth mentioning that the neural implicit method only needs a small number of images to train the model. References:Preusker et al., 2015. Shape model, reference system definition, and cartographic mapping standards for comet 67P/Churyumov-Gerasimenko–Stereo- photogrammetric analysis of Rosetta/OSIRIS image data. A & A 583, A33. https://doi.org/10.1051/0004-6361/201526349.Gaskell et al., 2008. Characterizing and navigating small bodies with imaging data. Meteorit. Planet. Sci. 43 (6), 1049–1061. https://doi.org/10.1111/j.1945-5100.2008.tb00692.xWatanabe et al., 2019. Hayabusa2 arrives at the carbonaceous asteroid 162173 Ryugu--A spinning top–shaped rubble pile. Science 364 (6437), 268–272. https://www.science.org/doi/10.1126/science.aav8032.Palmer et al., 2022. Practical stereophotoclinometry for modeling shape and topography on planetary missions. The Planetary Sci. J. 3 (5), 102. https://doi.org/10.3847/PSJ/ac460f.Chen et al., 2023. A new shape model of the bilobate comet 67P/Churyumov-Gerasimenko. Icarus. 401, 115566. https://doi.org/10.1016/j.icarus.2023.115566.Chen et al., 2024. Neural implicit shape modeling for small planetary bodies from multi-view images using a mask-based classification sampling strategy. ISPRS Journal of Photogrammetry and Remote Sensing. 212, 122-145. https://doi.org/10.1016/j.isprsjprs.2024.04.029.
Ground-to-space observations of the 20 May 2023 bolide over Australia
Authors: Silber Elizabeth , Ronac Giannone Miro , Schaible Loring , Sansom Eleanor , Devillepoix Hadrien , Edwards Thomas , Longenbaugh Randy , Boslough Mark , Bowman Daniel , Clemente Iona , Vida Denis , Šegon Damir
Published: July 2024

Very bright meteors, also referred to as fireballs and bolides, are generally produced by objects >10 cm in diameter. While impacts by large asteroids (10s of meters in diameter) are relatively rare, they are not statistically negligible. Such objects carry a destructive potential, as illustrated by the Chelyabinsk event that occurred over a decade ago. Thus, the characterization of these objects is of utmost importance, and helps shed light on why some events might result in more catastrophic outcomes than others. Different sensing modalities can be used in unison to derive various bolide parameters, including its trajectory, entry velocity, and energy deposition, among others. In addition to producing a spectacular display in the sky, bolides are also capable of generating shockwaves. A by-product of shockwaves is a low frequency (< 20 Hz) acoustic wave, or infrasound. Acoustic sensing using infrasound stations installed around the globe has gained momentum over the last decade due to its capability to detect bolides and help estimate their energy deposition irrespective of time of day or cloud coverage. Infrasound is generally used in conjunction with other sensing modalities, such as optical observations, which provide important ground truth information. We present the ground-to-space observations of an energetic bolide that resulted in an airburst over Australia on 20 May 2023. The bolide entered with a speed of 28 km/s over Queensland at 09:22 pm local time, and underwent a catastrophic disintegration at an altitude of 29 km. It deposited energy of ~7.2 kt of TNT equivalent (1 kt = 4.184·1012 J), making it one of the top 20 most energetic bolides detected by the US government sensors and reported in the JPL/NASA CNEOS database since 1988. The bolide was so bright that it was visible at a distance of 600 km. It saturated ground-based cameras, stifling efforts to derive the full trajectory and obtain photometric measurements. We found infrasound signals at four infrasound stations as far as 6000 km away. The energy estimate derived through infrasound signal analysis is ~7 kt of TNT equivalent, which corroborates the value reported by the CNEOS database. We will present observations of this energetic bolide event and discuss implications for planetary defense and characterization of similar events.SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.
Mars interannual variability during the dusty southern spring and summer season using Radio Occultation data
Authors: Krishnan Ananya , Karatekin Özgür
Published: July 2024

Dust is one of the major factors influencing the meteorology and climatology of the Martian atmosphere. Southern spring and summer on the planet Mars correspond to periods with increased dust activity.  These periods include pre-, near- and post-  perihelion regional dust storms [Kass et al., 2016]. The exact timing, size, location, and number of dust storms varies from year to year.  Increased dust content can affect a broad region by changing the atmospheric temperature as well as the water propagation from the lower to the upper atmosphere [Karatekin et al., 2023].Here, we use the Radio Occultation profiles to study the interannual variability during the dusty southern spring and summer seasons. Radio occultation is a remote sensing method for vertical profiling of both lower and upper atmosphere providing the variations in tropospheric temperatures as well as electron densities. The data sets we use are publicly available Mars Express (MEX) [Pätzold et al., 2004] and Mars Atmosphere and Volatile EvolutioN (MAVEN) [Withers et al., 2020] radio occultation experiments. Both conduct experiments with spacecraft components consisting of a radio transceiver and a High Gain Antenna (HGA). At the ground, the radio signals are transmitted and received using ESA’s Estrack and/or NASA’s Deep Space Network (DSN) radio antennas (34 m and 70 m). MEX uses simultaneous and coherent dual-frequency downlinks at X-band and S-band, whereas MAVEN uses a single frequency (X-band) to conduct RO experiments. Both MEX and MAVEN are in elliptical orbit. MAVEN makes observations in both ingress (spacecraft disappearing behind the planet as seen from Earth) and in egress (spacecraft reappearing from behind the planet as seen from Earth) with occultation opportunities occurring once per orbital period of approximately 4.5 hours [Withers et al., 2020]. Whereas MEX primarily makes ingress observations with 1–2 occultations per sol. The publicly available MEX and MAVEN residual Doppler measurements are analyzed with the ROB - RO data analysis code [Krishnan et al., 2023].The interannual changes and the variability of the upper atmosphere as well as the neutral atmosphere is investigated. The results are further compared with other observations like MCS and NOMAD and with numerical models as well.References:Kass, D. M., et al. (2016), Geophys. Res. Lett., 43, 6111 – 6118.
Karatekin, O., et al. (2023), Bulletin of the AAS, 55(8).
Pätzold, M., et al. (2004), Mars: Mars express orbiter radio science (Vol. 1240).
Withers, P., et al. (2020), Space Science Reviews, 216(61), 1–49.
Krishnan, A., et al. (2023), Radio Science, 58, e2023RS007784.
Acknowledgements:This research is financially supported by the PRODEX program managed by the European Science Agency (ESA) with help of the Belgian Science Policy Office (BELSPO). 
Surface Characterization of Hydrated Planetesimals inthe Main Asteroid Belt
Authors: Kwon Yuna , Masiero Joseph
Published: July 2024

As one of the most thermally stable solvents, water is critical to grasping the material evolution of planetary systems. Ch-type asteroids show clear signs of water on their surfaces, anticipated to serve as a local water reservoir in today’s main asteroid belt region and also as the parent bodies of CM meteorites that are presumably the primary water source on early Earth. Aside from the composition of their building blocks, little is known about the physical makeup of dust particles, which is related to environmental information before they settled in their current orbits. Observations revealed polarimetric differences in Ch-type asteroids in the optical, indicating potential dust gradients among the bodies. In this presentation, we will report interim results we obtained from our new optical multi-band photometric and near-infrared polarimetric observations of large (>~80 km in diameter) Ch-type main-belt asteroids and discuss what insights we have gained into constraining the evolution of the bodies.
A Prediction of the Inter-Annual Variability of Sulfur in Mercury’s Exosphere and Subsurface
Authors: Verkercke Sebastien , Chaufray Jean-Yves , Leblanc François , Morrissey Liam , Phillips Michael Steven , Munaretto Giovanni
Published: July 2024

Since the discovery of atoms ejected from Mercury’s surface and forming a tenuous atmosphere around the planet, Mercury’s surface-exosphere interface has been extensively observed by both on-ground and space-borne instruments. Between 2007 and 2011, the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft performed three fly-bys of Mercury followed by four years in orbit around it. This mission derived the surface composition of Mercury which notably includes some moderately volatile species such as sodium, potassium or sulfur. While the two former were clearly identified in Mercury’s exosphere, the latter has never been observed as released from the surface in its neutral form. Moreover, recent studies suggest that hollows, i.e. bright, shallow flat-floored depressions, could potentially be formed by local sulfur accumulation This suggests that sulfur should be present in both the surface and the exosphere of Mercury, with associated migration and/or diffusion processes that could sustain such geological features. Using a 3-D Exospheric Global Model with a Monte-Carlo test-particles approach and accounting for species diffusion in the first meter of Mercury’s regolith, this study aims for the first global prediction of the inter-annual variability of neutral sulfur density in both Mercury’s exosphere and subsurface. This work is particularly relevant for the preparation of ESA/BepiColombo mission which will start its scientific mission in December 2025.
Attempt to Using Machine Learning Technique for Temperature Profile Estimation
Authors: Ye Qian
Published: July 2024

Accurate temperature profile estimation is a critical component in various atmospheric studies and applications, including weather forecasting, climate modeling, and atmospheric dynamics research. This study explores the potential of employing machine learning techniques to enhance temperature profile estimation by combining data from satellite and reanalysis dataset. This study attempts to leverage the strengths of both datasets by employing machine learning algorithms to develop an ensemble model that combines the high-resolution satellite measurements with the global coverage of reanalysis dataset. Specifically, the eXtreme Gradient Boosting (XGBoost) algorithm, a powerful and efficient machine learning technique, is utilized to capture the complex relationships between the variables and produce enhanced temperature profile estimates

 

 

 
 