bluuebunny/crossref_metadata_2025 huggingface dataset:
The Orbits of the Regular Jovian Satellites and the Orientation of Jupiter's Pole
Authors: Jacobson Robert , Park Ryan
Published: July 2024

In support of the Juno mission currently in orbit about Jupiter, we have updated our ephemerides for the Galilean and four inner Jovian satellites, Amalthea, Thebe, Adrastea, and Metis (Jacobson, 2014 European Planetary Science Congress, Vol. 9). For the update we expanded the data set to include astrometry through 2018, mutual events through 2021, eclipse timings from 1650 to 2016, stellar occultations, occultations of the Juno spaceccraft, and Juno tracking data through early 2024. Our model for the satellite orbits is a numerical integration of their equations of motion expanded to include effects of tides raised on Jupiter by the Galilean satellites and the tide raised on Io by Jupiter, and general relativistic effects due to the Sun and Jupiter including the Lense-Thirring effect. We account for the external  perturbations from the Sun, Saturn, Uranus, and Neptune. The direct effects of the Moon, the inner planets, the dwarf planets, Ceres and Vesta, and the asteroids are ignored but the mass of the Sun is augmented with their masses to indirectly include their perturbations. We allow for the gravitational field of an oblate Jupiter and for the quadrupole gravitational fields of the Galilean satellites. The direction and precession of Jupiter's pole are needed to orient the Jupiter gravity field. The model for the motion of the pole is based on the rotational equations of motion for a rigid axially symmetric body. The applied torques are derived from the Sun, Saturn, Uranusand the Galilean satellites acting on Jupiter's figure. We numerically integrate the equations over a 400 year period and fit the integrated orientation angles with a Fourier series.In this paper we report on the results of our latest determination of the satellite orbits, the Jovian tidal parameters, and the Jupiter pole parameters. We find clear evidence that Io and Europa are spiraling inward while Ganymede is on an outward spiral. We also find that our pole model requires a Jupiter polar moment of inertia somewhat larger than most theoretical predictions.
The Curious Case of TOI-2267: Three Earth-sized Exoplanets in a Cool Star Binary System
Authors: Zúñiga-Fernández Sebastián , Pozuelos Francisco J. ,   SPECULOOS Team
Published: July 2024

Temperate small exoplanets around cool stars only recently moved onto the scientific centre stage but swiftly entered the spotlight. We yet have to assemble various puzzle pieces to understand what makes a true "Earth twin" in these systems (if it even exists). Open questions include the formation of these ubiquitous targets, probing evolution hypotheses of photo-evaporation and core-powered mass loss, and constraining habitability definitions.
We report the discovery and validation of three temperate Earth-sized exoplanets, TOI-2267.03 and .01, likely orbiting the primary and TOI-2267.02 likely orbiting the secondary in a binary system of cool stars (primary: M5V, 3030 K; secondary: M6V, 2890 K, separated by 0.4''). The exoplanet pair likely hosted by the primary star orbits close to a 3:2 mean motion resonance, with periods of 2.28 and 3.49 days. These findings are supported by multi-band ground-based photometry that allowed us to confirm the planetary nature of TOI-2267.01 and .03. However, TOI-2267.02 with a period of 2.03 days remains a candidate due to its shallower transit.
The configuration with the three planets orbiting the same stellar component suggests a highly dynamically unstable system, implying the possibility of planets orbiting both stars. To date, only one other system is hypothesized to harbor planets orbiting the two stellar components of a binary: three super-Earths orbiting the two stars of K2-132, two F stars separated by 1''. However, the extremely shallow transits of these candidates orbiting K2-132 prevent any confirmation, maintaining the actual architecture of the system unknown. Hence, TOI-2267 stands out as the only system today where the existence of this unique configuration can be confirmed.
We present the results of our global analysis, the validation of the planet candidates, the planet formation scenario, and the evidence supporting the most likely architecture of the system. We discuss future plans to verify the transit of the TOI-2267.02 candidate, disentangle the host star for each planet, and confirm this odd double planetary system. These results could open a new venue to search for and characterize planetary systems in binaries of low-mass stars, profoundly impacting our understanding of how protoplanetary disks evolve to form such double planetary systems, where TOI-2267 will be a benchmark system.
Effortless and accurate time series analysis in astronomy using Large Language Models
Authors: Smirnov Evgeny
Published: July 2024

The application of machine learning techniques in astronomy has been rapidly growing, addressing various challenges such as predicting orbital stability, classifying celestial objects, and analysing images. However, the emerging trend of using large language models (LLMs) presents a novel approach that relies on natural language processing and explicit task definitions, rather than on statistical algorithms or probabilistic models. In this talk, I'll demonstrate the exceptional capabilities of LLMs, specifically GPT-4 as well as some other open source alternatives, in analyzing visual patterns and accurately classifying asteroids as resonant or non-resonant without any training, fine-tuning, or coding beyond writing an appropriate prompt in natural language. By leveraging the power of LLMs, it is possible to achieve an accuracy, precision, and recall of 100% in differentiating between pure libration, circulation, and mixed (transient) cases of resonant angles.This approach introduces a new paradigm in astronomical data analysis, where complex tasks requiring human expertise can be completed with minimal effort and resources. The implications of this study extend beyond the identification of mean-motion resonances, as the methodology can be applied to a wide range of astronomical problems that involve pattern recognition, outlier detection, and decision-making tasks. This presentation will discuss the experimental design, results, and potential applications of LLMs in astronomy, highlighting the significance of this innovative approach in advancing astronomical research.
BioSigN:  using an exposure lab on the ISS for preparation of in situ life detection missions and habitability studies
Authors: de Vera Jean-Pierre Paul , Baqué Mickael ,   BioSigN team
Published: July 2024

BioSigN (BioSignatues and habitable Niches) is a space experiment supported by ESA and foreseen to be performed  in Low Earth Orbit on the exposure lab Exobio on Bartholoméo to be fixed outside the Columbus Module on the International Space Station (ISS). The main objective of BioSigN is to support and prepare future planetary exploration missions to Mars, Enceladus, Europa and/or Titan by conducting exposure experiments on the ISS. To maximize the scientific output, the outcome of BioSigN will be connected to the results obtained on ground from recent and up-coming planetary analogue field site studies and planetary simulation facilities. The BioSigN project is conceived to achieve three central objectives:To analyse to what extent selected organisms and (micro-)fossils acquired from Icy Moon/Marsanalogue field sites (terrestrial and ocean/deep sea location) can survive/outlast the conditions of space exposure;
To evaluate by the obtained results the habitability of present/past Mars and of the icy ocean worlds in the solar system.
To test the (in)stability of a particular set of bio-molecules when exposed to space and Mars-like conditions, and to investigate their mechanisms of resistance or degradation as well as analysing if they are still detectable by the commonly used life detection methods;
To reach these goals, the test samples will be exposed to space vacuum and space radiation, approaching icy-moon specific or planet-specific gaseous and solar environments. 
Cryogenic reflectance spectroscopy under high vacuum conditions for outer planets exploration
Authors: Helbert Jörn , Lorek Andreas , Maturilli Alessandro , Garland Stephen , Alemanno Giulia
Published: July 2024

The exploration of the outer solar system will be a strong focus of planetary exploration in the coming decades. NASA New Horizon has revolutionized our understanding of the Pluto-Charon system and has obtained the first resolved images of a Kuiper Belt Object. The ESA JUICE mission was successfully launched in 2022 to explore the Jovian system. The NASA Lucy mission is on its way to explore a number of Trojan asteroids. JAXA is currently studying a mission to Trojan with the option of sample return. NASA will soon launch the Europa Clipper mission. NASA and ESA are in discussion for a mission to study Uranus and Neptune.All these missions create a strong demand for laboratory spectra of analog materials obtained at low pressure or in vacuum at cryogenic temperatures. As a response to this demand by the planetary science community, the Planetary Spectroscopy Laboratory (PSL) of DLR is currently adding a new chamber with spectral capabilities towards low-T reflectance measurements under vacuum conditions.This new compact low-temperature vacuum chamber allows bi-directional reflectance measurements. This chamber is attached to a Bruker VERTEX 80V Fourier spectrometer allowing measurements from UV to far infrared. A two-stage turbo vacuum pump allows high vacuum to be obtained in the system. In a future extension backfilling with gas mixtures would allow simulating the extreme low-pressure atmospheres of the outer solar system bodies.The picture shows a view of the glove box for sample preparation that was added to the system based on the lessons learned during early tests for cryogenic measurements at PSL. Key is a cold finger with a cryocooler which allows preparation of icy samples as well as ice-dust mixtures under a dry air atmosphere. The prepared samples are fed into the vacuum chamber via the air lock at the back of the glove box. This provides maximumflexibility in preparing cryogenic samples while minimizing the risk of contamination and frost forming on the samples.
Observing system simulation experiment to reproduce Rossby wave in the Venus atmosphere
Authors: Komori Nobumasa , Sugimoto Norihiko , Fujisawa Yukiko , Abe Mirai , Kouyama Toru , Ando Hiroki , Takagi Masahiro , Yamamoto Masaru
Published: July 2024

At the cloud top of the Venus atmosphere, mid-latitude Rossby waves have been observed. They are considered to play an important role in the maintenance of the super-rotation. Here, we reproduce those waves in a general circulation model named AFES-Venus (Atmospheric GCM for the Earth Simulator for Venus [1]) by conducting an observing system simulation experiment with the help of a data assimilation technique (ALEDAS-V: AFES–LETKF Data Assimilation System for Venus [2]). The synthetic observations of horizontal winds associated with the Rossby wave are produced by a linear wave propagation model, and they are assimilated at the cloud top (~70 km) for 30 Earth days in realistic conditions, assuming they are derived from the cloud tracking of the ultra-violet images taken by the Venus climate orbiter “Akatsuki”. It is demonstrated using Eliassen–Palm fluxes that enhanced Rossby wave in the mid-latitudes induces a deceleration in zonal-mean zonal wind. After the stop of data assimilation, the model fields reached another quasi-equilibrium state within about 10 Earth days, indicating that the “memory” of assimilated observations can be kept for a while even new observations are not available. [1] Sugimoto, N., M. Takagi, and Y. Matsuda (2014a), J. Geophys. Res. Planets, 119, 1950–1968.[2] Sugimoto, N., A. Yamazaki, T. Kouyama, H. Kashimura, T. Enomoto, and M. Takagi (2017), Sci. Rep., 7(1), 9321.
The Planetary Data System Radio Science Sub-Node
Authors: Majid Walid , Kahan Daniel , Buccino Dustin , Lee Clement , Barbinis Elias , Yang Oscar , Tiscareno Matthew , Simpson Richard
Published: July 2024

NASA’s Planetary Data System (PDS) is an active archive of science data from NASA planetary missions. PDS archives and distributes peer-reviewed planetary science data to the world-wide planetary science community.  The Radio Science Sub-Node (RSSN) in collaboration with the Ring Moon Systems (RMS) Discipline Node aims to maintain a long-term radio science capability within PDS. Members of the RSSN team have strong connections to the NASA Deep Space Network (DSN), a long history of participation in radio science observations, and close relationships with the radio science community. RSSN plans to develop software tools and templates to assist data providers in the creation and ingestion of consistent PDS4-compliant data products as well as preparation and maintenance of mission-independent ancillary products from the DSN. RSSN will also develop software tools to assist data users in visualization and quick-look analysis of radio science data, enabling users to assess quality and usability early in their projects. With the constantly growing volume of data and the large variety of observation types, observing conditions, and object types, the development of metadata and quick-look tools will be critical in connecting scientists and other users to data of interest before committing to detailed analyses.In this presentation, we will describe the RSSN objectives, overview of recent developments, near-term plans, and engagement with the radio science community.
A novel metric for assessing planetary surface habitability
Authors: Woodward Hannah , Rushby Andrew , Mayne Nathan
Published: July 2024

Planetary surface habitability has so far been, in the main, considered in its entirety. The increasing popularity of 3-D modelling studies of (exo)planetary climate has highlighted the need for a new measure of surface habitability. Combining the observed thermal limits of Earth-based life with surface water fluxes, we introduce such a measure which can be calculated from the climatological outputs from general circulation model simulations. In particular, we pay attention to not only the bounds of macroscopic complex life, but additionally the thermal limits of microbial and extremophilic life which have been vital to the generation of Earth's own biosignatures. This new metric is validated on Earth, using ERA5 reanalysis data to predict the distribution of surface habitability which is then compared to the observed habitability created from satellite-derived data of photosynthetic life. Additionally, the validation against observed habitability is repeated for a selection of popular metrics of surface habitability, allowing for the first time a comparison of metric performance with respect to Earth-based surface life.
Analyzing the space environment of Saturn's moon Enceladus to probe its interior
Authors: Saur Joachim , Duling Stefan , Grayver Alexander , Szalay Jamey R.
Published: July 2024

Saturn's moon Enceladus is a moon generally considered to possess all necessary conditions for being a habitable planetary body. The Cassini spacecraft passed Enceladus on more than 20 close flybys within the time span 2005 to 2015. In our study, we analyze the measurements obtained during these flybys to investigate the time-spatial structure of Enceladus space environment. Despite no known deviations of Saturn's internal magnetic field from azimuthal symmetry, we show that the fields around Enceladus still contain time-variable components. Within the complex magnetic field environment caused by Enceladus' plumes, we subsequently search in Cassini measurements for signatures consistent with induced fields in order to probe the interior structure of Enceladus.
2D Dynamics of a lava flow on Europa
Authors: Bodin Bastien , Cordier Daniel , Davies Ashley
Published: July 2024

Planetary volcanism is a widespread phenomenon throughout the Solar System (Lopes et al., 2010). Volcanism can be classified into two categories: silicate-based volcanism, which occurs on telluric planets, and cryovolcanism, which may occur on several outer Solar System bodies (e.g., Geissler, 2015). Cryovolcanism is assumed to play a significant role in shaping the surfaces of many icy worlds. Evidence of cryovolcanic activity has been detected on Pluto (Singer et al., 2022) and Enceladus (Hansen et al., 2006); it is also suspected of being present on Europa (Fagents, 2003; Sparks et al., 2017) and Titan (Lopes et al., 2013).Modeling cryovolcanism is crucial for understanding the geological processes shaping the complex surface of Europa. In addition, investigating the resurfacing processes on this moon can improve our insight into subsurface chemophysical properties and prebiotic potential.Several numerical models of Europa cryovolcanism are already available in the literature, concerning either the possible eruption mechanisms (Lesage, Massol, and Schmidt, 2020) or the subsequent lava flow (Morrison, Whittington, and Mitchell, 2023). According to the scenario we have adopted, liquid water ascending to the surface through the volcanic conduit is significantly depressurized, resulting in a relatively dense mixture of vapor and small ice crystals, similar to terrestrial fluidized snow. This type of fluid has been recognized as having Bingham-like rheology (Maeno and Nishimura, 1979). We then developed a two-dimensional numerical model of the dynamics of such a fluid. We adopted a Smoothed-Particle Hydrodynamics (SPH) method (Gingold and Monaghan, 1977; Lucy, 1977), which is particularly relevant for systems with free surfaces. This makes SPH particularly relevant in the context of lava flow simulations (Prakash and Cleary, 2011; Bilotta et al., 2016).Focusing on the formation of so-called smooth plains, we have simulated the dynamics of possible effusive eruptions at the surface of Europa. In particular, we assess the influence of parameters governing the thermodynamic and rheological properties of the considered fluid.
Studying lunar Irregular Mare Patches and lava tubes with the Lunar Geology Orbiter
Authors: Poppe Sam , Broz Petr , Sofge Kimberly , Kereszturi Akos , Losiak Anna , Hauber Ernst , Divoký Martin , Kohout Tomáš , Hargitai Henrik , Bohovic Roman , Viru Jaan , Pajusalu Mihkel , Carrer Leonardo , Bruzzone Lorenzo , Gomes Ricardo , Peace Johannes , Saimoon Islam Quazi , Sauro Francesco , Fernando Benjamin
Published: July 2024

INTRODUCTIONA better understanding of  lunar geology is critical both scientifically and practically for exploring and settling the Moon in the next decades. Improving our knowledge about the formation and evolution of the Moon helps us 1) to understand the geology of Earth and other terrestrial bodies in the Solar System, and 2) to prepare for in-situ utilisation of lunar resources. Irregular mare patches (IMPs), as well as lava tubes, pits and caves are such lunar geological phenomena that offer progress with both tasks. Even though multiple IMPs were found on the surface of the Moon, their age and formation processes remain enigmatic. Furthermore, many pits have been detected in various lunar geological settings, but it remains uncertain whether any of these openings could lead to extended cave conduits underground. The proposed Lunar Geology Orbiter LUGO aims primarily to reveal the formation ages and mechanisms of IMPs, and secondarily to identify the distribution and dimensions of lava tubes for future exploration.WHY IRREGULAR MARE PATCHES?Controversy surrounds the formation age of IMPs because very few impact craters are present at their surface. Whereas one scenario assumes that IMPs consist of compact igneous rocks and thus are relatively young (>100 My), another scenario assumes the existence of old (
Physical Modeling of Meteors based on Radar Data
Authors: Gritsevich Maria , Kastinen Daniel , Kero Johan
Published: July 2024

Understanding meteor phenomena involves deciphering not only the physical properties of meteoroids but also their dynamic histories. While various ground- and space-based instruments can capture these phenomena, High-Power Large-Aperture (HPLA) radar systems stand out for their capacity to offer superior data with enhanced sensitivity and extended detection ranges, enabling the study of fainter meteors. Despite these advantages, meteor head echo detection with radar systems encounters inherent limitations, particularly regarding the inability to track the entire trajectory of meteors due to the narrow observational volume. This limitation often leads to missing the initial phase of the atmospheric meteor trajectory, where crucial information regarding pre-entry velocity, orbit determination, and mass estimation remains elusive. In this study, we introduce a new approach to processing radar meteor head echo detection by embedding a physical model that enables the reconstruction of meteoroid trajectories based on partial detection. Using the observational data obtained with MU radar, we demonstrate that this method is capable of addressing the limiting factor of radar volume and resolving the challenge of estimating pre-atmospheric velocity of meteoroids. This capability drastically improves our ability to interpret radar observations, offering a more comprehensive exploration of both sporadic meteors and meteor showers. It allows for the reconstruction of trajectories of faint meteors that may not be detectable by other means, such as optical techniques. This approach bridges the gap between radar detection and self-consistent physical modeling, enhancing current understanding and extending interpretability of a wider range of meteor phenomena.
Dynamical and Chaotic Structures in the Trans-Neptunian Region: Insights from Resonance Analysis and Diffusion Rates
Authors: Forgács-Dajka Emese , Kővári Emese , Kovács Tamás , Sándor Zsolt , Kiss Csaba
Published: July 2024

The trans-Neptunian space, home to numerous small bodies known as trans-Neptunian objects (TNOs), exhibits diverse dynamical behaviors and serves as a valuable probe into the Solar System's history. These TNOs, relics of past dynamical events, reflect significant changes in the positions of the giant planets over time. Our comprehensive survey, using the FAIR method on over 4,000 TNOs from the JPL database, identified several mean-motion resonances (MMRs) with Neptune and characterized resonant behavior through short-term and long-term libration patterns.This region's structure is significantly influenced by celestial mechanical resonances, including MMRs, secular resonances, and the Kozai resonance. Through a large-scale survey employing dynamical maps, we pinpointed key MMRs and assessed their roles using chaotic diffusion and stability time analysis. Chaotic diffusion rates indicate the long-term evolutionary trends and stability times of TNOs, offering insights into the chaotic nature and stability of their orbits. Studying these resonant behaviors and diffusion rates provides a deeper understanding of the past dynamics of the Solar System, including the migration of giant planets and their impact on smaller bodies. This research maps the overall structure of the trans-Neptunian region, refining existing dynamical classifications and contributing to predictions of the Solar System's future evolution. 
CO2 in Ganymede’s exosphere revealed by JWST
Authors: Bockelee-Morvan Dominique , Poch Olivier , Leblanc François , Zakharov Vladimir , Lellouch Emmanuel ,   ERS Ganymede team
Published: July 2024

Jupiter's icy moon Ganymede has been seen to have a tenuous exosphere produced by sputtering and possibly sublimation of water ice. To date, only hydrogen and oxygen have been detected in this exosphere (Barth et al., 1997; Hall et al. 1998; Roth et al. 2021). Here, we report on the first detection of CO2 in Ganymede's exosphere through observations of the 4.3 microns band with the NIRSPec/IFU instrument of the James Webb Space Telescope. Maps of the CO2 gas distribution over the leading and trailing hemispheres reveal an unexpected patchy CO2  exosphere. CO2 gas is observed over different terrain types, principally those exposed to intense Jovian irradiation, but also over some bright or dark terrains. The highest CO2 column density is found over the north polar cap of the leading hemisphere, which also has unique surface ice properties. The distribution and production mechanisms of CO2 vapor will be discussed using simulations of Ganymede's exosphere (Leblanc et al. 2017) and through comparison with maps of surface ice properties obtained with JWST (Bockelée-Morvan et al. 2024).References:*Barth, C.A., Hord, C.W., Stewart, A.I.F., Pryor, W.R., Simmons, K.E., McClintock, W.E., Ajello, J.M., Naviaux, K.L., Aiello, J.J.: Galileo ultraviolet spectrometer observations of atomic hydrogen in the atmosphere of Ganymede. GRL 24(17), 2147–2150 (1997) *Bockelée-Morvan, D., Lellouch, E., Poch, O., Quirico, E., Cazaux, S., de Pater, I., Fouchet, T., Fry, P.M., Rodriguez-Ovalle, P., Tosi, F., Wong, M.H., Boshuizen, I., de Kleer, K., Fletcher, L.N., Meunier, L., Mura, A., Roth, L., Saur, J., Schmitt, B., Trumbo, S.K., Brown, M.E., O’Donoghue, J., Orton, G.S., Showalter, M.R.: Composition and thermal properties of Ganymede’s surface from JWST/NIRSpec and MIRI observations. A\&A 681, 27 (2024) *Hall, D.T., Feldman, P.D., McGrath, M.A., Strobel, D.F.: The Far-Ultraviolet Oxygen Airglow of Europa and Ganymede. The Astrophysics Journal 499(1), 475–481 (1998) https://doi.org/10.1086/ 305604 *Leblanc, F., Oza, A.V., Leclercq, L., Schmidt, C., Cassidy, T., Modolo, R., Chaufray, J.Y., Johnson, R.E.: On the orbital variability of Ganymede’s atmosphere. Icarus 293, 185–198 (2017) *Roth, L., Ivchenko, N., Gladstone, G.R., Saur, J., Grodent, D., Bonfond, B., Molyneux, P.M., Rether- ford, K.D.: A sublimated water atmosphere on Ganymede detected from Hubble Space Telescope observations. Nature Astronomy 5, 1043–1051 (2021) 
Geothermal non-equilibria as prebiotic selector
Authors: Matreux Thomas , Aikkila Paula , Schmid Almuth , Braun Dieter , Mast Christof B.
Published: July 2024

Life is an out-of-equilibrium process, pointing towards an emergence that must also have been decisively shaped and driven by the non-equilibrium systems present 4 billion years ago. Rocks and their constituent phases likely played an essential role as molecular feedstock. We aim to combine this geological scenario with physical non-equilibria such as thermal gradients, offering unique opportunities for molecular selection.
We have studied how simple heat flows through geological networks of interconnected chambers create chemical niches with complex mixtures of prebiotically relevant substances, each with different concentration ratios (1). These confined spaces could thus enable various prebiotic reactions and boost their yield and selectivity compared to bulk systems. We show this exemplarily with the trimetaphosphate-driven dimerization of glycine. Trimetaphosphate, presumably rare on the early Earth, experiences strong thermophoresis and is accumulated significantly stronger than for instance glycine, increasing product yields by multiple orders of magnitude.
Prebiotic reactions often require a defined set of ion concentrations. One example is the activity of some important RNA enzymes that vanishes without divalent magnesium salt, whereas an excess of monovalent sodium salt reduces enzyme function. However, leaching experiments show that relevant geomaterials such as basalts release mainly sodium and only little magnesium. In heated rock cracks, the superposition of convection and thermophoresis actively enriches magnesium ions against sodium and establishes a habitat for ribozyme function from basaltic leachates (2). Interestingly, the same process can also solubilize one of the most abundant phosphate minerals on the early Earth, Apatite, by fractionation of its acidic-dissolved constituents.Under pH conditions relevant to nascent life, this leaves up to 15 mM of phosphate in solution, facilitating the formation of condensed, more reactive phosphate species.
References(1) Matreux, T., Aikkila, P., Scheu, B., Braun, D. & Mast, C. B. Heat flows enrich prebiotic building blocks and enhance their reactivity. Nature 628, 110–116 (2024).(2) Matreux, T. Le Vay, K., et al. Heat flows in rock cracks naturally optimize salt compositions for ribozymes. Nat. Chem. 13, 1038–1045 (2021).
Global morphology of ENA emissions from the atmosphere-magnetosphere interactions at Europa and Callisto
Authors: Haynes C. Michael , Tippens Tyler , Addison Peter , Liuzzo Lucas , R. Poppe Andrew , Simon Sven
Published: July 2024

We analyze the emission of energetic neutral atom (ENA) flux from charge exchange between Jovian magnetospheric ions and the atmospheres of Callisto and Europa. For this purpose, we combine the draped electromagnetic fields from a hybrid plasma model with a particle tracing tool for the energetic ions. We determine the ENA flux through a spherical detector that encompasses the entirety of each moon's atmosphere, thereby capturing the complete physics imprinted in these emission patterns. In order to constrain the modifications to the ENA emissions that arise from the periodic change of the ambient plasma conditions, we calculate the emission morphology at multiple positions during a Jovian synodic rotation. To isolate the influence of field line draping, we compare to the emission patterns in uniform fields. Our major results are:(a) At Europa and Callisto, the majority of detectable ENA emissions are concentrated into a band normal to the Jovian magnetospheric field. (b) The fraction of observable ENA flux that contributes to this band depends on the number of complete gyrations that the parent ions can complete within the moon's atmosphere. (c) Field line draping partially deflects impinging parent ions around both moons, thereby attenuating the ENA flux and driving significant morphological changes to the emission patterns. (d) The band of elevated ENA flux contains a local maximum and a local minimum in intensity, on opposite sides of each moon. At Europa, detectable ENA emissions are maximized slightly west of the ramside apex. At Callisto, they maximize near the Jupiter-facing apex.
Investigating Martian mantle melting: Insights into Shergottite origins, thermal evolution, and potential melting under the Tharsis region
Authors: Pierru Rémy , Bonnet-Gibet Valentin , Françoise Matéo , Dominijanni Serena , Parisiades Paraskevas , Andriambariarijaona Léon , Zhao Bin , Pandolfi Silvia , Boccato Silvia , Blanchard Ingrid , Guignot Nicolas , Henry Laura , King Andrew , Badro James , Michaut Chloé , Antonangeli Daniele
Published: July 2024

The InSight Mars lander, which is NASA's 12th mission under the Discovery program, was dedicated to studying the deep interior of the planet. The lander successfully landed in November 2018 [1] and since the beginning of winter 2019, the SEIS broadband seismometer has continuously recorded the seismic activity of the planet until December 2022 [2-3]. The results obtained during the first two years of the nominal mission have enabled a single-station seismic analysis of the interior of Mars, covering the subsurface and upper crust [4], placing constraints on discontinuities within the crust and the depth of the crust-mantle boundary [5]. However, the ability to fully exploit the seismic records from the SEIS seismometer to produce accurate compositional, structural, and dynamical models of Mars depends critically on knowledge of the melting properties, density, viscosity, and sound velocity of the relevant minerals, liquids, and mineralogical Martian assemblages under appropriate thermodynamic conditions.Here, we present an experimental investigation into the melting behavior of a simplified Martian mantle composition under high pressures and using in situ methods, extending up to 20 GPa. Our investigation reveals that the solidus of the Martian mantle is lower than those reported in the literature, primarily attributed to the presence of Fe3+ within the FMQ (Fayalite-Magnetite-Quartz) buffer. The presence of Fe3+ could facilitate the incorporation of water, thereby potentially lowering the melting point. This study highlights the intriguing stability of magnetite and garnet within a narrow pressure range of 3-4 GPa. This phenomenon holds significant implications for understanding the mineralogical composition of Mars' mantle and its geological processes. The melt produce at this pressure is identifies a probable or similar source for some basaltic shergottites characterized by a superchondritic CaO/Al2O3 ratio and low Al2O3 content, offering insights into the origins of Martian lavas. Our results also contribute to a new paradigm in understanding the thermal evolution of the Martian mantle. We propose a thermal model wherein crustal extraction occurs progressively over an extended duration spanning approximately 1 billion years. This model predicts a present-day mantle temperature of 1533 K and a corresponding lid thickness of 333 km. Finally, this study raises intriguing questions about the potential for ongoing partial melting beneath the Tharsis region on Mars. While the possibility of such activity persists, it is likely confined to very low melt fractions (
Numerical simulations of atmospheric waves in Saturn's upper atmosphere
Authors: Iñurrigarro Rodriguez Peio , Medvedev Alexander S. , Müller-Wodarg Ingo C. F. , Moore Luke
Published: July 2024

In the atmospheres of the Solar System planets, several kinds of atmospheric waves can be found. They are an important atmospheric phenomenon as, besides disturbing the atmosphere, they can also alter the mean structure and affect the general circulation [1]. Therefore, understanding their effects on the atmospheric dynamics is of paramount importance.The thermospheres of the Giant Planets are hotter than what would be expected if solar heating were considered the only energy source. Historically, the few existing numerical models have had difficulties to reproduce the observed temperature structure at mid and low latitudes. It was long thought that waves propagating vertically might play an important role in determining the temperature by either heating the thermosphere [2, 3] or by weakening the intense high-latitude westward jets allowing the meridional transport of energy trapped in the polar regions [4, 5]. Recently, the detection of gravity waves in Saturn's thermosphere has been reported using data from Cassini INMS and UVIS occultation data [4, 5, 6].The Saturn Thermosphere-Ionosphere Model (STIM) is the only 3D general circulation model published so far for Saturn's upper atmosphere [7, 8]. The model couples dynamically and chemically the thermosphere and the ionosphere. In this work, we have used the STIM model to perform high resolution numerical simulations of Saturn's thermosphere. They show the development of supersonic spiral gravity waves in the northern and southern auroral regions driven by the high latitude forcing produced by Joule heating and ion drag. We analyze the morphology and properties of these waves, their propagation and the forcing they impose on the mean flow. We also show simulations with forcing introduced at the bottom of the model to explore waves that can propagate through the thermosphere and their potential impact on the circulation. References:[1] Vallis. Atmospheric and Ocean Fluid Dynamics. Cambridge University Press, Cambridge, UK, 2006.[2] Young et al. Gravity waves in Jupiter's thermosphere. Science, 276, 1997.[3] O'Donoghue et al. Heating of Jupiter's upper atmosphere above the Great Red Spot. Nature, 536, 2016.[4] Müller-Wodarg et al. Atmospheric Waves and Their Possible Effect on the Thermal Structure of Saturn's Thermosphere. Geophysical Research Letters, 46, 2019.[5] Brown et al. Evidence for gravity waves in the thermosphere of Saturn and implications for global circulation. Geophysical Research Letters, 49, 2022.[6] Brown et al. A pole-to-pole pressure-temperature map of Saturn's thermosphere from Cassini Grand Finale data. Nature Astronomy, 4, 2020.[7] Müller-Wodarg et al. A global circulation model of Saturn's thermosphere. Icarus, 180, 2006.[8] Müller-Wodarg et al. Magnetosphere-atmosphere coupling at Saturn: 1 – Response of thermosphere and ionosphere to steady state polar forcing. Icarus, 221, 2012.
Shaping early molecular live by physical selection pressures
Authors: Braun Dieter
Published: July 2024

We will only fully understand the origin of life when we can recreate it in the laboratory. I report on our latest progress in building an autonomous evolution machine. A first step towards molecular evolution is the assembly of RNA from single nucleotides. We found that a moderate temperature difference at an air-water interface is an ideal micro-reactor for this process. The fluctuating interface continuously forms new dry spots by evaporation, driving the ring-opening polymerization of 2',3'-cyclic nucleotides toward RNA strands [1] and their length selective accumulation [2], including sequence-dependent phase transitions [3], showing fast evolution for DNA model systems [4] and accumulating prebiotic molecules by a thermal subsurface network [5]. The reaction only required a moderate alkaline pH and operated in a wide range of temperatures (4-80°C). The propagation of information is critical. Under the same pH conditions as above, we found templated ligation of RNA strands with 2',3'-cyclic ends. We see that both the formation and ligation is enhanced by amino acids. Surprisingly, the interface setting also shows signatures of modern cell biology: RNA is encapsulated into vesicles when lipids are added [2]. Even the components of modern cells assemble at the interface: a highly diluted PURE system accumulated at the air-water interface, triggering the expression of proteins such as GFP. Thus, interfaces control a remarkable variety of key steps in the evolution of life, making us optimistic that a prebiotic evolutionary machine can be created in the laboratory sooner rather than later.[1] ChemSystemsChem doi.org/10.1002/syst.202200026 (2022)[2] Nature Chemistry, doi.org/10.1038/s41557-019-0299-5 (2019)[3] PNAS doi.org/10.1073/pnas.2218876120 (2023)[4] Nature Physics doi.org/10.1038/s41567-022-01516-z (2022)[5] Nature doi.org/10.1038/s41586-024-07193-7 (2024)
Energetic Ion Dynamics in Pluto's Induced Magnetosphere
Authors: Ruch Randy , Simon Sven , Haynes C. Michael
Published: July 2024

New Horizons observations show an extensive depletion region at Pluto’s wakeside as a result of the interaction of heliospheric ions with Pluto’s induced magnetosphere. This rarefaction arises despite the ions having gyroradii multiple orders of magnitude greater than the dwarf planet’s radius. The interaction is studied by employing an energetic particle tracing tool in conjunction with electromagnetic field output from a hybrid plasma simulation of Pluto’s interaction region. The tracing of incident heliospheric ions across a range of energies will be used to analyze the deflection mechanisms responsible for the formation of this depleted region at Pluto’s wakeside.Additionally, periodic variations in energetic ion flux have been identified within the wake region. We investigate whether particle deflection as a result of the field from bi-ion waves produced by the shear flow between solar wind and pick-up ions can explain the periodicities observed in the wake. 
Towards a machine learning classification model of asteroids' co-orbital regimes
Authors: Azevedo Tiago , Ciacci Giulia , Di Ruzza Sara , Barucci Andrea , Alessi Elisa Maria
Published: July 2024

The aim of this work is to classify co-orbital motion at different timescales using a machine learning approach. Asteroids that move, on average, in a 1:1 mean motion resonance with a given planet, under the assumptions of the restricted three-body problem, are of special interest, because they follow very stable orbital configurations. The capability of classifying this kind of dynamics in an automatic way is of paramount importance to understand key mechanisms in the solar system but also for space exploration and exploitation missions. Starting from the analysis of Tadpole, Quasi-Satellite and Horseshoe regimes on a medium timescale, we apply features extraction and machine learning algorithms to the timeseries of the relative angle between the asteroid and the planet. The dataset is composed of pseudo-real timeseries computed by means of the JPL Horizons system (thus considering a full dynamical model) and simulated data computed by means of the REBOUND software. In a second step, the process is enriched to also be able to classify relative transitions between different co-orbital motions and between resonant and non-resonant dynamics, thus also considering much longer timescales. To this end, different algorithms are evaluated, starting from classical statistical approaches to more advanced deep learning ones.
Crustal magnetic fields' effect on the day-night transportation process in the Martian ionosphere
Authors: Fan Kai , Fraenz Markus , Wei Yong , Cui Jun , Pan Yongxin , Yan Limei , Wang Yuqi , Chen Si , Dubinin Eduard
Published: July 2024

Mars is typically regarded as a non-magnetic planet. Currents in the Martian ionosphere generate a Venus-like induced magnetosphere to standoff the solar wind flows and to pile up the interplanetary magnetic fields. However, crustal magnetic fields in the southern hemisphere influence local plasma properties. Whether the crustal magnetosphere could be sustained is highly debatable and still uncertain. This work aims to provide evidence of a local crustal ’mini-magnetosphere’ in satellite observations on the Martian dayside, includes Mars Express, MAVEN, and Tianwen-1. The trapping effect causes different flow patterns while the crustal fields rotate to different sub-solar regions but are attenuated at higher altitudes. Observations provide essential information to investigate the effect of the crustal magnetic fields on heavy ion flows and understand the role of the crustal magnetic fields in the interaction between the solar wind and the Martian atmosphere.
Meteorites Colliding Craters Inversion based on Kernel Gaussian Mixture Ridge Regression
Authors: Zhao Wei , Han Wei , Liu Peng
Published: July 2024

Inverting kinetic energy impacts of high-speed meteoroids is an effective means to study the dynamics of celestial impact, thereby, evaluate the impact effects and hazards. This paper uses a Smoothed Particle Hydrodynamics method based Celestial Impact Dynamics (PySPH-CID) to simulate the ejecta and crater evolution process of meteorites colliding into Earth; and a Kernel Gaussian Mixture Ridge Regression (KGMRR) method is proposed to fit the one-to-many mapping between cause and effect of an impact with multiple sets of feasible solutions; a solution space is obtained using Gaussian Process (GP), for the formation conditions of craters after a small celestial body impacts. An inversion of colliding crater of Yilan in Heilongjiang Province, Northeast China, 46°23'03'' N and 129°18'40'' E, with 1.85km diameter, which located entirely on the cretaceous granite bedrock and preserved the remnants of two-thirds of the crater rim, was made. Assuming the impactor diameter is around 120m, preliminary experiment gives colliding cause vectors that impact velocities range between 17.8~15.0 km/s with 60.7°~66.6° obliquely incident, impactor density varying in scope of 2772~2815 kg/m3. This work provides a direct reference for effectively defending against the threat of foreign celestial bodies to the Earth, developing and transforming controlled impact technologies, as well as implementing precise and controllable impacts.
Artificial intelligence at the service of space astrometry: a new way to explore the solar system
Authors: Quaglia Giulio , Lainey Valery , Tochon Guillaume
Published: July 2024

Advancements in artificial intelligence (AI) have opened new horizons for space exploration, particularly in the domain of astrometry. This research investigates the integration of AI techniques, specifically deep neural networks, with space astrometry using the Cassini-Huygens images database. The primary objective is to train a neural network for the detection and classification of astronomical sources, in particular stars, satellites and cosmic rays, in order to process them for a better understanding of our solar system, performing an analysis on the spatial and temporal variation of cosmic rays and moreover to a wider investigation on the characteristics of the Saturn system.The methodology employed involves a multi-step process. Firstly, known stars and satellites' positions are located in the images using ARAGO (IMCCE), a software package designed for the astrometric measurement of natural satellite positions in images taken using the ISS of the Cassini spacecraft, resulting in more than 13,000 images (8bit, 1024x1024, exposure duration
Secular Variation on Jupiter and Stochastic Modelling of its Magnetosphere
Authors: Loncar Marco , Jackson Andrew
Published: July 2024

From the earliest interplanetary missions investigating magnetism, comparisons with features of Earth’s magnetic field have been of the utmost interest. In particular, the ability of a planetary field to change with time has only ever been conclusively observed on Earth and its detection on other bodies would be vital for the understanding of planetary dynamos. With the Juno spacecraft in orbit about Jupiter since 2016, a continuous time series of magnetic measurements now exists over an extended period. This provides a suitable foundation by which to study any potential secular variation and determine its validity.
Some of the first indications of secular variation have been attributed to the advection of Jupiter’s magnetic field by flow in the form of zonal winds. This was first postulated with respect to variations between the measurements of Juno and earlier satellites such as Pioneers 10 and 11 and Voyager 2. Subsequent work has been carried out using select data from the Juno spacecraft, that has proposed these observations can account for differential rotation in the planet’s deep interior and a time varying zonal flow (the latter suggesting the detection of Alfvén waves as a means of describing the behaviour).
Although such deductions lend credence to the detection of secular variation, they must be subject to continued analysis. This is tackled through the investigation of the null hypothesis, in which Jupiter’s field is taken to be static and subsequently analysed to see if its behaviour can be adequately described. Such models are constructed through regularised inversion and then subject to residual analysis. Through these means, we find conclusions relating Juno data to earlier spacecraft, difficult to unambiguously determine.
In addition to this, the effect of the magnetosphere of Jupiter on satellite measurements is not concretely understood. A problem with this lies in the potential for unmodelled phenomena to influence subsequent internal field models. The majority of models take the external field to be uniform with its source in the magnetodisc – this describes a ring current, tilted with respect to Jupiter’s equatorial plane. The effect of this is the production of a uniform field adequately described by an order l = 1 spherical harmonic expansion. To supplement this uniform field, a stochastic treatment is considered in which averaging over randomly oriented currents contributes to large scale correlations. The resulting model describes a uniform magnetodisc as well as the remaining non-uniform currents distributed about Jupiter. Such a treatment is yet to be applied to the case of a planetary magnetosphere but has shown its power in the treatment of seamounts and crustal magnetisation on Earth.