bluuebunny/crossref_metadata_2025 huggingface dataset:
Curiosity rover TLS-SAM measurements consistent with localized methane containment and transport by 3-D atmospheric circulation in Gale crater
Authors: Pla-Garcia Jorge , Rafkin Scot , Ruíz-Pérez María , Atreya Sushil , Gómez Felipe
Published: July 2024

The Curiosity rover has traversed more than 30 km from the landing site at the very bottom of Gale crater and has climbed more than ∼800 m into the Mt. Sharp foothills over more than five Martian years. During nighttime, downslope winds originating from both Mt. Sharp and crater rims would prevent the nighttime accumulation of methane released along the slopes above the cold pool and facilitate the convergence and accumulation of methane in the bottom of the crater [Figure, Panel A]. As a result, any methane released along the slopes at night is quickly transported downslope. After sunrise [Figure, Panel B], the crater circulation transitions to an upslope regime. The reversal of the circulation should transport the methane accumulated in the bottom of the crater upslope as shown in MRAMS model tracer fields, that also indicate a substantial horizontal mixing that rapidly dilutes the methane-enriched air mass. Any methane released along the slopes is transported horizontally and vented out of the crater. MRAMS model predicts a methane front of peak values to pass higher elevations at increasingly later times after sunrise, moreover later in the morning (~10:00 LMST), but usually with highly and increasingly diluted with time methane values. At mid-morning (Figure, Panel C), upslope circulation along surface rims is fully developed and there is a clear horizontal divergence at bottom of crater where methane is highly diluted due to 3-D atmospheric mixing and increasingly advected upslope out of crater. At dusk, downslope winds starts to develop through sloped surfaces of Mt. Sharp, as well as the cold pool of air at the bottom of the crater, which begins to trap methane released from the ground to start the cycle again (Figure, Panel D). Consistent with [Pla-García et al. 2019] and [Moores et al. 2019] the 3-D crater circulation supplemented by the growth and collapse of the PBL is necessary to explain the TLS-SAM methane observations.
Dynamics and potential origins of decimeter-sized particles around comet 67P/Churyumov-Gerasimenko
Authors: Pfeifer Marius , Agarwal Jessica , Marschall Raphael , Grieger Björn , Lemos Pablo
Published: July 2024

The activity of comets is still not fully understood. During the European Space Agency's Rosetta mission to comet 67P/Churyumov-Gerasimenko, the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) aboard the spacecraft captured numerous image sequences of the comet's near-nucleus coma to record the dynamics of ejected dust particles. Studying their dynamics can help to understand their ejection processes.At the typical recording distances of 50 km or more, even the largest dust particles (~ 1 cm) cannot be spatially resolved and instead appear as (thousands of) point sources that move through the image sequences. In Pfeifer et al. (2022), we therefore developed an algorithm to track these particles automatically.Here, we now present the dynamics, size-frequency distributions, potential origins, and implications regarding the ejection process of hundreds of decimeter-sized particles that we tracked through OSIRIS image sequences and traced back to the nucleus surface (see also Pfeifer et al. 2024). Pfeifer et al. (2022): https://doi.org/10.1051/0004-6361/202141953
Pfeifer et al. (2024): https://doi.org/10.1051/0004-6361/202346380
Impact of ion-neutral chemistry on Ganymede's ionosphere
Authors: Beth Arnaud , Galand Marina , Modolo Ronan , Leblanc François , Jia Xianzhe
Published: July 2024

The Galileo spacecraft flew by Ganymede, down to 0.1 RG from the surface for the closest, six times giving us insight into its plasma environment. Its ionosphere, made of ions born from the ionisation of neutrals present in Ganymede's exosphere, represents the bulk of the plasma near the moon around closest approach. As it has been revealed by Galileo and Juno, near closest approach the ion population is dominated by low-energy ions from the water ion group (O+, HO+, H2O+) and O2+. As we showed in [1] by means of a test particle model, the ion composition during most flybys was a priori dominated by H2+and O2+. However, during Juno's flyby of Ganymede, plasma data revealed the additional presence of H3+ that may only stem from ion neutral reactions between H2 and H2+.  We have updated our test particle model to account for these ion-neutral collisions of which  H2 + H2+. We show how it modifies the ion composition compared with [1] and assess the role of these collisions in the production of new ion species within Ganymede's exo-ionosphere. This will help to interpret plasma observations made by Juno and in the future by JUICE around Ganymede. [1] Beth et al., EGU24, https://doi.org/10.5194/egusphere-egu24-11772, 2024
The physical mechanism of the streaming instability, and whether it works in vortices
Authors: Magnan Nathan , Heinemann Tobias , Latter Henrik
Published: July 2024

A major hurdle in planet formation theory is that we do not understand how pebbles congregate into planetesimals. A promising way to overcome this metre-scale barrier involves a mechanism called the streaming instability (SI). This hydrodynamic instability gathers the pebbles into clumps so dense that they collapse gravitationally and form planetesimals.Unfortunately, the mechanism responsible for the onset of this instability remains mysterious. This makes it hard to evaluate the value of the SI as a planetesimal formation theory: how robust is the mechanism, how does it saturate, etc.Fortunately, some significant progress has been made recently: J. Squire and P. Hopkins showed that the SI is a Resonant Drag Instability (RDI) involving inertial waves. In the first part of this talk, we build on their insight to produce a clear physical picture of how the SI develops.Like all RDIs, the SI is built on a feedback loop: in the ‘forward action’, an inertial wave concentrates pebbles into clumps; in the ‘backward reaction’, those drifting pebble clumps excite an inertial wave. Each process breaks into two mechanisms, a fast one and a slow one. At resonance, each forward mechanism can couple with a backward mechanism to close a feedback loop. Unfortunately, the fast-fast loop is stable, so the SI uses the fast-slow and slow-fast loops. Despite this last layer of complexity, we hope that our explanation will help understand how the SI works, in which conditions it can grow, how it manifests itself, and how it saturates.Another problem is that the SI can only develop in regions containing a high density of similar-sized pebbles. Those conditions are met in large-scale vortices, but no one knows if the SI can feed on vorticial flows. Indeed, each instability can only grow in a few specific flows, and a priori the SI is active in Keplerian flows, not vortex flows. We answer this long-standing question in the second part of the talk.To do so, we develop a simple pen-and-paper model of a pebble-laden vortex in a protoplanetary disc. We find that if the vortex is weak and anticyclonic, pebbles drift towards its centre. We then build a vortex analog of the shearing box to analyse the local linear stability of our pebble-laden vortex. We find that the pebbles’ drift powers an instability which closely resembles the SI. Indeed, both rely on the same resonance between the pebble drift and inertial waves. This result strengthens the case for vortex-induced planetesimal formation.
The role of magnetic topology and plasma pressure on the ionopause formation at Mars
Authors: Stergiopoulou Katerina , Sánchez-Cano Beatriz , Lester Mark , M. Fowler Christopher , J. Andrews David , Xu Shaosui , J. T.  Edberg Niklas , Joyce Simon , Holmström Mats , Meggi Dikshita , K. Turner Anna , R. Gruesbeck Jacob
Published: July 2024

At planets with no intrinsic dipolar magnetic field such as Mars, an ionopause is often formed, a boundary that separates the planetary plasma from the solar wind. The ionopause boundary and its formation drivers in the upper dayside ionosphere of Mars are yet to be fully characterised. In this study, we use observations from NASA's MAVEN mission to probe the Martian upper dayside ionosphere and describe the physics of the ionopause boundary as well as its variability drivers. We develop an automated method to identify the ionopause as the location of sharp gradients in electron density and temperature. We focus on the 8th MAVEN deep dip campaign (DD8) from October 2017 that consists of 50 consecutive orbits. The trajectories of the DD8 orbits are similar to each other and thus, the impact of the changing upstream conditions on the Martian ionosphere can be studied. We utilise and compare data from several instruments on board MAVEN, namely the LPW, SWEA, STATIC, SWIA and MAG instruments, in order to investigate in detail the factors controlling the ionopause. We find that the ionopause formation is correlated with the plasma pressure balance between the ionosphere and the magnetosheath, and with changes in magnetic topology. More specifically, an ionopause in most cases is formed where there is a change from closed to either open or draped magnetic field lines.
Towards HADES: Deeply probing of Lava World Atmospheres
Authors: Keles Engin
Published: July 2024

Transmission spectroscopy of exoplanet atmospheres enables us to infer the characteristics of planets in foreign stellar systems. Terrestrial planets are of special interest as they increase our understanding of their origin and evolution preparing us to characterize a true Earth-analog planet in the future. Recent discoveries confirmed the presence of rocky planets in very short orbits, resulting in surface temperatures above the critical value of 2000K, where the surface rocks start to melt and release silicates into the atmosphere. Such worlds are denoted as Lava worlds and show different molecules with a large number of absorption lines.Such molecules allow us to characterize lava world atmospheres even with ground-based high-resolution transit observations applying the cross-correlation method. More specifically, by applying injection recovery, in which template spectra are injected and recovered from the observations, it is possible to infer the lower limit of the atmospheric mean-molecular weight value, giving key insights into the atmospheric redox-state, recycling efficiency of atmophile elements between the melt-pool and solid-interior and atmospheric composition of lava worlds.Recent JWST observations showed the likely presence of a CO/CO2 dominated atmosphere on the rocky planet 55 CNC e inferred from eclipse observations. This hints at the absence of a tenuous vaporized rock atmosphere, and the presence of a volatile dominated atmosphere. A volatile-rich atmosphere would result in a low mean-molecular weight atmosphere, making it possible to be inferred by applying ground-based observations.We present several recent ground-based high-spectral resolution (R = 50 000) observations of 55 CNC e acquired at the Large-Binocular- telescope with the PEPSI instrument and show preliminary results on the inferred mean-molecular weight value. We compare this to the recent JWST results and discuss the implication of the results concerning the atmospheric redox state and the recycling efficiency of atmophile elements between the melt pool and solid interior.
NOAA’s Space Weather Follow-On (SWFO) Program
Authors: M Hill Steven , Vassiliadis Dimitrios , Redmon Rob , Johnson Jeff
Published: July 2024

The National Oceanic and Atmospheric Administration (NOAA) Space Weather Follow-On (SWFO) program includes a suite of in situ plasma instrumentation on the SWFO-L1 spacecraft along with compact coronagraphs (CCOR) on both SWFO-L1 and the GOES-U geostationary weather satellite. GOES-U is currently slated to launch in June 2024 and SWFO-L1 is slated to launch in April 2025. Here we provide an overview of the spacecraft and missions along with their instrumentation and products. The GOES-U CCOR-1 will be the first coronagraph flown for operational space weather monitoring. The SWFO-L1 in situ instruments include the Solar Wind Plasma Sensor (SWiPS), SupraThermal Ion Sensor (STIS), and a pair of fluxgate magnetometers (MAG). The in situ measurements for the plasma and interplanetary magnetic field (IMF) will be critical for driving NOAA’s magnetospheric and ionospheric models in real time. The suprathermal ion and electron measurements will be useful for early forecasts of arrival of geoeffective structures such as CMEs and interplanetary shocks. NOAA’s National Environmental Satellite, Data, and Information Service (NESDIS) will provide tracking and control along with data acquisition for the observations. The Space Weather Prediction Center (SWPC) will perform the real-time processing, product generation, and dissemination. The National Centers for Environmental Information (NCEI), part of NESDIS, will curate the data products for non-real-time (retrospective) users to browse and access via a comprehensive API and the upcoming Space Weather Portal. The SWFO Program will complement existing and planned observations from other satellites currently in NOAA’s satellite fleet along with satellites of partner domestic and international partner organizations.
Laboratory investigation of mechanical energy dissipation relevant to rocky interiors of small icy moons
Authors: Seltzer Cassandra , O. Ghaffari Hoagy , Peč Matěj
Published: July 2024

The habitability of icy moons in the outer Solar System is linked to their ability to maintain warm subsurface oceans through time, but the mechanisms leading to heat generation in small icy moons are not well constrained. While most heat generation in response to tidal forcing is thought to occur in icy crusts and water oceans, the deformation of chondritic material thought to make up rocky cores and mantles has not previously been studied comprehensively in a laboratory setting under relevant planetary conditions. We experimentally deformed samples of the Kilabo meteorite, an LL6 chondrite, under axial strain rates of 10-5 s-1 and confining pressures up to 100 MPa. We recorded the strength of the material, measured energy dissipation through acoustic emission events, and observed ultrasonic wavespeeds as a function of confining pressure. Our results suggest that dissipative brittle deformation is possible even during isotropic pressurization, as well as at low stresses and strains during nominally “elastic” deformation, due to the porous nature of the material. However, energetic acoustic emission events associated with brittle deformation become less powerful as confining pressure increases. The mechanical behavior of the meteoritic material also evolved as a function of increasing confining pressure: peak strength occurred at 50 MPa confining pressure, and material continuously stiffened as pressure increased. These pressure-dependent properties indicate that larger icy moons could have stiffer, less deformable silicate layers than those found in small icy moons, corresponding to a lower relative contribution of silicate deformation to the bodies’ total heat budgets. Future experiments on carbonaceous chondrites under oscillatory loading conditions are necessary to fully measure the potential magnitude of tidal heating in rocky silicate cores of icy moons.  
HDO Modeling in a 3D Climate Model of Venus
Authors: Li Dan , Montmessin Franck
Published: July 2024

HDO is an isotopic form of water that can provide clues about the history and evolution of water. By comparing the ratio of HDO to H2O on Venus with that of other planets or comets that have similar origins, we can estimate how much water Venus received during its formation and early evolution. The Venus Global Climate Model (VGCM) developed in several laboratories (LMD, LATMOS) of Institute Pierre-Simon Laplace (IPSL, in Paris area) can simulate the dynamics of the Venusian atmosphere. However, VGCM does not include the influence of HDO. In this work, we dedicate to implement HDO as a new tracer into the model to investigate the influence of HDO fractionation and spatial and temporal distribution. Two new tracers are added, HDO(g) and HDO(l), to account for both the vaporous phase and the condensed phase. As an isotope of water, HDO participates in many chemical and physical processes where water is involved. Therefore, we implement HDO(g) and HDO(l) in every routine where H2O(g) and H2O(l) are present except for photochemical processes. The initial value for HDO is set to 10-2 times the value of H2O. HDO(l) is then calculated by using the equation of the isotopic fractionation of water during condensation. The results indicate that when there is no isotopic fractionation, HDO(g) and HDO(l) are exact copies of H2O(g) and H2O(l).
Characterising the atmosphere of GJ1214 b with JWST observations.
Authors: Lavvas Panayotis , Paraskevaidou Sofia , Arfaux Anthony
Published: July 2024

GJ-1214b, discovered by Charbonneau et al. (2009), is a transiting super-Earth/mini-Neptune with an M4.5-type host star at 14.6pc from the Sun. GJ-1214b is notable for its featureless transmission spectrum (Gillon et al., 2014; Kreidberg et al., 2014), which has been interpreted as evidence for the presence of clouds (ZnS, KCL) or photochemical hazes (Morley et al. 2013, 2015; Charnay et al. 2015; Gao and Benneke 2018; Ohno & Okuzumi 2018, Adam et al. 2019; Kawasima et al. 2019; Lavvas et al. 2019; Ohno et al. 2020; Christie et al. 2022). Latest observations of GJ 1214 b with JWST reveal a high-albedo atmosphere (Kempton et al. 2023), possibly rich in photochemical hazes (Gao et al. 2023). We use a self-consistent model coupling among photochemistry, radiative transfer, thermal structure and haze & cloud microphysics to characterise the atmosphere of GJ1214b. We explore different metallicity cases to constrain the atmospheric composition and evaluate different scenarios for the photochemical haze mass fluxes and the eddy mixing efficient. We particularly focus on the interplay between photochemical hazes and clouds, considering the formation of ZnS, KCL and NaCL clouds on hazes.We demonstrate that the novel JWST thermal emission observations provide much better constraints on the atmospheric metallicity compared to transit spectra alone, limiting the retrieved metallicity to values between ~1000x-3000x solar. Our results demonstrate that the atmospheric albedo is in the order of 10-20%, considering both the contributions of hazes and clouds. Transit spectra are mostly affected by hazes rather than clouds, but the implications of the clouds on the atmospheric thermal structure provide an indirect effect to affect the transit signature. We further discuss the role of sulfur chemistry in the formation of the haze and its potential signature in the transit spectra.
Impact of hot exozodiacal dust on the polarimetric analysis of close-in exoplanets
Authors: Ollmann Kevin , Wolf Sebastian , Lietzow-Sinjen Moritz , Stuber Thomas
Published: July 2024

Interferometric near- and mid-infrared observations revealed that about one-fifth of nearby stars are surrounded by dust of as yet unknown origin - hot exozodiacal dust (HEZD). Since HEZD is located  at orbital radii comparable to those of close-in exoplanets, its presence has a potential influence on the analysis of the scattered-light polarization of close-in exoplanets and vice versa.We analyze the impact of HEZD around main-sequence stars on the polarimetric characterization of close-in exoplanets and vice versa by identifying characteristic polarimetric signatures of HEZD and close-in exoplanet. We find that the dust grain radius has the strongest influence on a polarimetric analysis due to its significant impact on the wavelength-dependent polarization characteristics and the total order of magnitude of the scattered-light polarization. In certain scenarios, the scattered-light polarization of the HEZD even exceeds that of the close-in exoplanet, for example for a dust grain radius of 0.1 μm, a HEZD mass of 8*10-10 Μ⊕ , an orbital HEZD radius of 0.04 au and an orbital inclination of 90°. In summary, the presence of HEZD needs to be considered in any effort to characterize exoplanets via polarimetric observations. Stricter constraints on the model parameters (especially on the dust grain radii) are required to restrict the potentially resulting scattered-light polarization.
YunMa: Advancing Atmospheric Cloud and Haze Analysis in the Next-Generation Exoplanet Data Era 
Authors: Ma Sushuang , Ito Yuichi , Al-Refaie Ahmed Faris , Changeat Quentin , Edwards Billy , Tinetti Giovanna
Published: July 2024

The analysis of exoplanetary spectroscopic data, captured by next-generation instruments like Webb, emphasizes the importance of accurately modeling clouds and hazes. While retrieval studies have emerged as one of the key methods for interpreting spectroscopic data, originating from data analysis of missions like Hubble and Spitzer, existing models often oversimplify clouds and hazes, making them inadequate for interpreting the higher-quality data from instruments like Webb and the coming Ariel mission.In response to this challenge, we developed YunMa (Ma et al. 2023), a comprehensive cloud and haze model optimised for retrieval studies that integrates particle size distribution and radiative-transfer simulations. YunMa is versatile, serving as both a standalone model and an integrated component within the TauREx spectral retrieval framework.We demonstrate YunMa's capabilities and present simulations and retrievals of various cloud and haze types. Our results explore the potential of extracting features from data collected by Webb and Ariel, as well as conducting large-scale simulations for exoplanet population studies, incorporating detailed chemistry and cloud modeling. References:Ma et al 2023 ApJ 957 104 doi 10.3847/1538-4357/acf8ca
Characterizing Lunar Materials: Spectral Analysis of Apollo 16 and Lunar Meteorite
Authors: Tripathi Prateek , Maturilli Alessandro , Alemanno Guilia
Published: July 2024

Interpreting the surface composition of the Moon and other airless bodies relies heavily on spectroscopic techniques spanning visible and near-infrared wavelengths. This study employed an integrated spectroscopy approach to measure and characterize a suite of lunar rock samples, a lunar meteorite, and lunar minerals. The primary objective was to demonstrate the methodology for building a robust spectral library that can support the interpretation of data from future lunar missions focused on understanding surface compositions and resource potential.The analog samples characterized included 15 lunar mineral endmembers (pigeonite, augite, ilmenite, orthopyroxenes, olivine, anorthite, and bytownite), an Apollo 16 regolith sample (62231.44), and the Tisserlitine 001 lunar meteorite. These materials were prepared as fine powders sieved to grain sizes ranging from 25 to 125 micrometers. Spectroscopic measurements were performed under vacuum conditions using the state-of-the-art Bruker Vertex 80V FTIR instruments at the Planetary Spectroscopy Laboratory. Bidirectional reflectance spectroscopy was employed to acquire spectra at illumination angles of 30° and 45° relative to the sample surface normal, utilizing attached visible and near-infrared detectors. Hemispherical reflectance measurements were conducted to collect visible and near-infrared spectra separately, using integrating spheres.  The calibrated hemispherical reflectance spectrum for the Apollo 16 sample exhibits a clear hydroxyl group feature near 3 micrometers, consistent with previous observations. Despite originating from different locations, the Apollo 16 lunar sample and the Tisserlitine 001 lunar meteorite displayed striking similarities in their visible and near-infrared bidirectional reflectance spectra, exhibiting absorption features characteristic of lunar highland compositions, including broad 1 and 2 micrometer bands indicating the presence of pyroxenes. However, the Tisserlitine 001 sample had slightly more pronounced pyroxene bands, although the overall spectral shape and absorption features were comparable between the two samples.Further spectral analysis revealed notable observations. Ilmenite exhibited the highest overall reflectance, followed by orthopyroxene and pigeonite, while anorthite and bytownite displayed relatively low reflectance across most wavelengths. Olivine exhibited a distinct 10 micrometer absorption feature. Interestingly, the Tisserlitine 001 lunar meteorite displayed a unique spectral signature distinct from the other minerals studied. The study's findings contribute to developing a robust spectral library to aid in identifying lunar mineralogy and chemistry from orbital or landed measurements, enabling assessments of resource potential and improving understanding of lunar formation processes.
SUDA: A SUrface Dust Analyser for compositional mapping of the Galilean moon Europa
Authors: Kempf Sascha ,   SUDA Science Team
Published: July 2024

The Surface Dust Analyser (SUDA) is a dust impact mass spectrometer onboard of the Europa Clipper mission for investigating the surface composition of the Galilean moon Europa. The instrument is a Time--Of--Flight (TOF) impact mass spectrometer derived from previously flown dust compositional analyzers on Giotto, Stardust, and Cassini. SUDA uses the technology of the successful Cosmic Dust Analyzer (CDA) operating on Cassini and employs advanced reflectron-type ion optics for increased mass resolution. The instrument will measure the mass, speed, charge, elemental and isotopic composition of impacting grains.Atmosphereless planetary moons such as the Galilean satellites are wrapped into a ballistic dust exosphere populated by tiny samples from the moon's surface produced by impacts of fast micrometeoroids. SUDA will measure the composition of such surface ejecta during close flybys at Europa to obtain key chemical constraints for revealing the satellite's composition, history, and geological evolution. Because of their ballistic orbits, detected ejecta can be traced back to the surface with a spatial resolution roughly equal to the instantaneous altitude of the spacecraft.SUDA will detect a wide variety of compounds from Europa's surface over a concentration range of percent to ppm and connect them to their origin on the surface. This allows simultaneous compositional mapping of many organic and inorganic components, including both major and trace compounds, with a single instrument. Any recent tectonic activity, cryovolcanism, or resurfacing event is detectable by variations in the surface composition. This can be linked to corresponding geological features, including the analysis of compositional variations across large craters on Europa. SUDA will further the understanding of Europa's surface couples to its interior source regions.In this presentation, we will discuss SUDA's unique capabilities to collect compositional ground truth from orbit and how SUDA contributes to the Europa Clipper science goals.
A new technique to derive the temperature of the cold ions in the magnetosphere
Authors: Li Kun
Published: July 2024

The polar wind, consisting of ions and electrons with low temperature and low energy, is known as a main contributor to the ionospheric outflow. These ions in the polar wind are so-called cold ions, which are notoriously difficult to measure with a spectrometer onboard the spacecraft because of the spacecraft charging problem. Recently, a technique measuring the electric field in the plasma wake has been used to derive the bulk velocity of the cold ion flow. However, this technique is not able to derive the cold ion temperature, which is thought to change as ions travel in the magnetotail. In this study, we use the electric field measurements from the Cluster spacecraft. We focus on the correlation between the ion temperature and the width of the plasma wake. Our results are used to derive the cold ion temperature, which helps us to understand more about the dynamics of cold ion outflow.
Quantitative Assessment of Open-Source Methods for Generating Random Porous Media
Authors: Skorov Yuri , Reshetnyk Volodymyr , Lukyanyk Igor , Grynko Yevgen , Macher Wolfgang , Schuckart Christian , Blum Jürgen
Published: July 2024

In the research presented, a quantitative assessment is conducted on multiple publicly available methods for generating random porous media. The creation and examination of such media are fundamental to various models that offer a more advanced level of physical analysis concerning the transfer of energy and matter. These foundational models of porous media facilitate the quantification of crucial parameters like radiative thermal conductivity and volumetric absorption of external radiation. These parameters, in turn, play a critical role in simulating heat transfer within porous surface layers, like those found on comets or asteroids, influencing the effective brightness temperature of these layers. Therefore, the modelling of random porous media directly influences the analysis of remote microwave observations and the derivation of constraints on the characteristics of the objects under investigation.The comparison among various open-source codes intended for generating porous layers is carried out. These methods can be categorised based on different criteria. For instance, they can be distinguished by methods that regulate contacts between elementary units (like YADE) and those that lack such control. The methods can also be classified by the particle types forming the structure, which can include spheres of different sizes, porous clusters composed of such spheres, or solid non-spherical particles. In the analysis of polydisperse media, a consistent application of particle size distribution laws and size value constraints is ensured for comparison purposes. Furthermore, packings consisting of cubes, tetrahedrons, octahedrons, and irregularly shaped particles are considered for non-spherical particles. In the case of hierarchical layers, aggregates of various sizes and degrees of nonsphericity are evaluated. The generated layers are compared based on parameters such as porosity, average pore size, permeability, and the depth distribution of the first and last particle collisions with the dust skeleton. The last parameter is vital to estimate gas heating upon passing through the layer and the resultant gas yield. Additionally, the computational performance associated with implementing the selected methodologies is thoroughly examined.
SP@M: a medium-energy particle detector for the M-MATISSE mission
Authors: Nenon Quentin , Devoto Pierre , André Nicolas , Thomas Vincent , Prech Lubomir , Němec František , Sanchez-Cano Beatriz
Published: July 2024

M-MATISSE is an ESA Medium class candidate (M7 call) in phase A study. M-MATISSE would place two spacecraft in orbit around Mars to study the solar wind – magnetosphere – ionosphere – atmosphere coupling at the red planet. Amongst the comprehensive payload of M-MATISSE, the Mars Ensemble of Particle Instruments (M-EPI) includes a low-energy neutral and ion detector, an electron spectrometer, and a medium-energy particle instrument.For M-MATISSE and the M-EPI package, IRAP and its partners are developing the Solar Particles @ Mars (SP@M) experiment to study 30 keV to 1 MeV electrons and 30 keV to 10 MeV ions. The main scientific objective of SP@M is the characterization of Solar Energetic Particles (SEPs) and suprathermal particle populations throughout the Martian magnetosphere and atmosphere. This characterization is essential to understand atmospheric escape, SEP-induced aurorae, and radar blackouts. It would also advance the assessment of radiation risk for future robotic and human missions to Mars.SP@M would employ 8 detection units per spacecraft, 4 dedicated to electrons and 4 to ions. Each detection unit would use a single thick SSD (thickness of 1 to 1.5 mm) suitable for the targeted energy range. In this presentation, we will introduce the phase A activities of the instrument, including the mechanical and electronics design of SP@M, the electron-ion discrimination strategy, and simulations of the expected performances.
Anatomy of a comet tail transited by the Juno spacecraft en route to Jupiter
Authors: Connerney Jack , Jorgensen Peter , Jorgensen John , Benn Mathias , Andersen Anga , Denver Troelz , Bolton scott
Published: July 2024

A star camera aboard the Juno spacecraft traveling from Earth to Jupiter serendipitously recorded the impact of interplanetary dust particles (IDPs) by imaging bits of the spacecraft ejected from the IDP impact sites. In essence, the Juno spacecraft, with its expansive ~60 m2 of solar arrays, served as a dust detector with orders of magnitude more aperture than dedicated dust detectors specifically designed and flown to detect dust impacts. Consequently, Juno recorded many impacts with the larger (few to tens of micro-meters) and less numerous IDPs that populate the inner solar system, establishing for the first time their distribution and source (Jorgensen et al., 2020). Six months prior to its arrival at Jupiter, the Juno spacecraft recorded a singular burst of interplanetary dust particle impacts attributed to passage through the extended tail of a comet. That comet has now been identified as the recently discovered Jupiter family comet P/2019 S3 Pan-STARRS (SPKID 1003641), affording a unique opportunity to characterize the dynamical motion of the comet’s dust tail. Dust impacting the spacecraft orbits under the influence of radiation pressure forces and gravity (ratio b = ~0.05), escaping the comet nucleus ~2 years prior to impact on the spacecraft and ~1 year post comet perihelion. Impacting dust, with an implied radius of ~10 mm, escaped the comet nucleus with a radial velocity of ~120 ms-1, appropriate to a comet with a radius of a few km.
Tunneling Toward Interstellar PAHs: O and H’s Quantum Leap 
Authors: Campisi Dario
Published: July 2024

Polycyclic aromatic hydrocarbons (PAHs) are widely observed in space both in the gas phase and as components of interstellar dust. PAHs account for ~20% of the carbon (C) in space. Understanding the mechanism to unlock C from PAHs is important to shed light on the formation of complex organic molecules (COMs), which play a crucial role in regulating the physics and chemistry of our universe and aiding in the origin of life [1]. While COM formation often begins with CO activation via hydrogenation on the surface of interstellar grains,  the breakdown of gas-phase PAHs could provide an alternative pathway. PAHs often host radicals such as oxygen (O) and hydrogen (H), which weaken their aromatic bonds. While superhydrogenation of PAHs is well-studied [2], their interaction with atomic O as a possible route for their fragmentation remains underexplored [3].Using density functional theory (DFT) and instanton theory [4], we predicted intermediate formations resulting from the reaction of O with naphthalene in the gas phase (Figure 1) and computed accurate tunneling rates. Similar to PAH hydrogenation, DFT suggests a sequence of O attachment. Once atomic oxygen reacts with the first C atom of naphthalene, intersystem crossing occurs from the triplet to the singlet spin state. O initially bridges Cs in naphthalene, catalyzing the barrier-less breakdown of a C-C bond, thus forming a heterocyclic ring. Subsequent oxygenation breaks down the PAH structure. Computed instanton rates reveal that tunneling is dominant at temperatures below 50K, with both O and C atoms tunneling through the potential barrier, aiding in the opening of the aromatic ring. Once one of the PAH rings is opened, the attack of two H leads to the fragmentation of the PAH, forming formaldehyde. These findings may clarify the role of PAHs in the formation of COMs, potentially linking them to the organic inventory formation in star-forming regions [1]. Figure 1: Oxygenation (in red) and hydrogenation (in black) tunneling of naphthalene aiding in fragmentation in the gas phase.References[1] Tielens, A. G. G. M. Rev. Mod. Phys. 2013, 85, 1021.[2] Campisi, D.; et al. Phys. Chem. Chem. Phys. 2020, 22, 1557-1565.[3] Cavallotti, C.; et. al. J. Phys. Chem. Lett. 2020, 11, 22, 9621–9628.[4] Rommel, J. B.; et. al. J. Chem. Theory Comput. 2011, 7, 3, 690–698.
The interstellar dust detection conditions with the DESTINY+ Dust Analyzer 
Authors: Krüger Harald , Strub Peter , Sommer Maximilian , Moragas-Klostermeyer Georg , Sterken Veerle , Khawaja Nozair , Trieloff Mario , Kimura Hiroshi , Hirai Takayuki , Kobayashi Masanori , Arai Tomoko , Hillier Jon , Simolka Jonas , Srama Ralf
Published: July 2024

The DESTINY+ spacecraft will be launched to the active asteroid (3200) Phaethon in 2025. The spacecraft will be equipped with the DESTINY+ Dust Analyzer (DDA) which will be a dust telescope hosting a time-of-flight impact ionization mass spectrometer. In addition to the composition of impacting dust particles, the instrument will measure the particle mass, velocity vector, and surface charge.
Here, we study the detection conditions of DDA for interstellar dust during the DESTINY+ mission. We use the interstellar dust module of the Interplanetary Meteoroid environment for EXploration model (IMEX; Sterken et al., 2013; Strub et al., 2019) to simulate the flow of interstellar dust through the Solar System. Extending earlier work by Krüger et al. (2019) we here consider the entire DESTINY+ mission, i.e. the Earth-orbiting phase of the spacecraft during the initial approximately 1.5 years after launch, the nominal interplanetary mission phase up to the Phaethon flyby, and a four-years mission extension beyond the Phaethon flyby. The latter may include additional asteroid flybys.
To predict dust fluxes and fluences we take into account a constraint for DDA to not point closer than 90 degrees towards the Sun direction for health and safety reasons of the instrument and in order to avoid electrical noise generated by solar photoelectrons.
For the Earth orbiting phase after launch of DESTINY+ our simulations predict that up to 28 interstellar particles will be detectable with DDA in 2026. In the following years the interplanetary magnetic field changes to a focussing configuration for small (
Ion escape from degenerate induced magnetospheres: The case of Mars
Authors: Zhang Qi , Barabash Stas , Holmström Mats , Wang Xiao-Dong , Futaana Yoshifumi , Fowler Christopher M , Ramstad Robin , Nilsson Hans
Published: July 2024

When the cone angle of the solar interplanetary magnetic field (IMF) becomes small, induced magnetospheres of unmagnetized planets degenerate, resulting in a markedly different mode of the interaction. In this case, solar wind protons penetrate all the way to the top of the atmosphere on the dayside of Mars. Ions from the ionosphere propagate upstream in the solar wind, toward the Sun, with a substantial flow perpendicular to the solar wind flow. We investigate the ionospheric ion escape from such an object. This study specifically concentrates on hybrid simulations of the ionospheric ion escape from Mars in the case of the 4° cone angle with the other solar wind conditions typical. The total escape rate is found to be almost one order of magnitude higher than for the typical Parker spiral case. The unique feature of the degenerate induced magnetosphere is the upstream escape driven by the ambipolar field, contributing 42% to the total escape rate, fully absent in the Parker spiral case. Additionally, 52% of the total escape occurs through the cross-flow plume, arising from the drift of ionospheric ions in the weak convective field and IMF. This channel dominates and is seven times more intense than the plume driven by the convective field in the nominal case. Understanding how degenerate magnetospheres operate is important not only for the planets in the solar system, but also for exoplanets.
Stable stratification of the helium rain layer yields vastly different interiors and magnetic fields for Jupiter and Saturn
Authors: Markham Stephen , Guillot Tristan
Published: July 2024

At sufficiently high pressures (>~ Mbar) and low temperatures (103-104 K), hydrogen and helium become partly immiscible. Interpretations of Jupiter and Saturn's magnetic fields appear to favor the existence of a statically stable layer near the Mbar pressure level. We seek to demonstrate that the phase separation of hydrogen and helium is capable of producing a layer of static stability and an internal structure consistent with magnetic field measurements. From experimental and computational data for the hydrogen-helium phase diagram we ƒind that moist convection and diffusive convection are inhibited, implying a stable helium rain layer in both Jupiter and Saturn, but with a significant difference in terms of structure and evolution: In Jupiter, helium settling leads to a stable yet super-adiabatic temperature gradient that is limited by conductive heat transport. The phase separation region should extend on only a few tens of kilometers instead of thousands in current-day models, and be characterized  by a sharp increase of the temperature of about ~500 K for standard phase separation diagrams. In Saturn, the fact that helium rains occurs much deeper implies a helium flux that is much larger, relatively to the total planetary mass. We find that the significant (positive) latent heat associated with helium condensation implies that a large fraction, perhaps close to 100%, of the planet's intrinsic heat flux, may be locally transported by the sinking helium droplets. This implies that contrary to Jupiter, the temperature gradient in that region may be much lower, perhaps even subadiabatic, leading to Saturn possessing a much more extended helium-rain region, consistent with interior models constrained by seismological constraints. This also accounts, at least qualitatively, for the differences in strength and characteristics of the magnetic fields of the two planets: Jupiter's strong, complex, magnetic field and high Lowes radius (80 to 83% of the planetary radius) is consistent with the existence of a narrow stable helium-rain region and a convective metallic hydrogen envelope below. On the other hand, Saturn's ten times weaker, axisymmetric field may be consistent with a dynamo powered by compositional motions in a mostly stable helium-rain metallic region. Dedicated models are required to test these hypotheses.
Dust dynamics in forming resonant planetary systems
Authors: Picogna Giovanni , Marzari Francesco
Published: July 2024

A fraction of the known planetary systems are observed in (or close to) mean motion resonances. These sample provides a unique opportunity, since they preserve the condition of their formation and early evolution of their orbits. The dynamics of the gas and dust in these systems is particularly interesting, as the resonant planets can open a common gap and migrate together. If the migration is directed outwards, the dusty ring formed at the outer edge of the gap would move together with the planets, potentially disentagling the dust distribution from the gas one. During planet migration the dust overdensity encounters several ice lines that suddenly change the dust size distribution, and thus its dynamical coupling with the gas and the gravitational interaction with the planets, potentially affecting its concentration. We modelled the evolution of a sample of protoplanets embedded in their natal disk with the hydrodynamical code PLUTO where a population of Lagrangian particles is introduced to track the dynamical evolution of a range of particles from dust to planetesimals. We focus in particular on the effect that dust evaporation/condensation at the ice-lines might have on the dust concentration at the gap edge during planet migration. We generate mock observations and discuss the role of ice lines on the observability of transition and debris disks.
Simulations of Rock-Ice Mixtures in the mantles of water-rich planets
Authors: Kovacevic Tanja , González-Cataldo Felipe , Militzer Burkhard
Published: July 2024

Determining the stable phase of the binary rock-ice mixture at extreme conditions is crucial for structure and evolution models. Yet, research into rock-ice interactions at pressure and temperature conditions exceeding those found on Earth remains limited. The discovery of new exoplanets points to some of them having substantial water abundance, implying that the interaction between an overlying layer of ice and the underlying rock would occur under several megabar of pressure. We determine the solvus temperatures for magnesium silicates and water across pressures relevant to the deep interiors of super-Earth to sub-Neptune sized bodies by atomistic simulations. Using density functional theory molecular dynamics simulations, we investigate the miscibility of magnesium silicates (MgSiO3 and MgO) and water ice (H2O) up to 8000 K and from 0.3-2 Mbar, using a heat-until-it-mixes approach to determine liquidus conditions. Our findings reveal that MgSiO3 becomes miscible in H2O upon melting in the entire pressure range we explored. Surprisingly, we observe a significant depression in the melting point of MgO by over 2000 K in the presence of H2O, highlighting complex interactions between rock and water at extreme conditions. These findings have implications for structure and evolution models, including those of the deep interiors of the ice giants, as well as for considerations ofplanet habitability.  
Petrography and geochemistry of the Ribbeck aubrite recovered from asteroid 2024 BX1, the closest analog to Mercury?
Authors: Hamann Christopher , Greshake Ansgar , Hecht Lutz , Jenniskens Peter , Kaufmann Felix , Luther Robert , Van den Neucker Aurélie , Helbert Jörn , Spurný Pavel , Borovička Jiří , Gattacceca Jérôme , Anand Aryavart , Kleine Thorsten , Braukmüller Ninja , Becker Harry , Schmitt-Kopplin Philippe , Krietsch Daniela , Schuppisser Anja , Busemann Henner , Goderis Steven
Published: July 2024

Meteorite recoveryAsteroid 2024 BX1 was discovered by astronomer K. Sárneczky at 21:48 UTC on 20 January 2024. NASA’s Scout and ESA’s Meerkat impact assessment systems soon identified it as a potential impactor and predicted that it would pass over Nennhausen, ~60 km W of Berlin, Germany, between 00:15 and 00:51 UTC on 21 January. At this time, a fireball was observed by eyewitnesses and recorded by allsky cameras of the European Fireball Network, IMO/All-Sky7, and FRIPON. Bolide analysis and strewn field calculations [1] indicated that strong winds blew the surviving meteorites to the SE, predicting a fall just south of Ribbeck. Starting on 22 January, a systematic search was carried out by scientists and students of MfN, DLR, FU Berlin, TU Berlin, the SETI Institute, and the Arbeitskreis Meteore. The first meteorite, totaling 171 g, was found by meteorite hunters on 25 January just west of Ribbeck. Two students from our team found two smaller meteorites (8.1 and 4.7 g) on 26 January, proving that the strewn field model was correct. Searching continued until 20 March and revealed about 200 reported finds with a total mass of >1770 g.Strewn fieldThe strewn field extends along a ~1 km wide and ~8 km long, WNW-ESW oriented corridor just south of Ribbeck (where meteorites of between 50 and 230 g were found) and Berge and Lietzow (where meteorites 5 km than predicted. The distribution of total mass per kilometer along the strewn field is approximately constant (~230 g/km) until the distribution of small (6 km due to sampling bias or a lack of small masses during fragmentation.Petrography of the Ribbeck aubritesPetrographic observations revealed that Ribbeck is an aubrite, which are rare enstatite achondrites [2–4]. The Ribbeck meteorites are fragmental breccias predominantly composed of up to 1.2-cm-sized, mostly angular, FeO-free, homogeneous enstatite (En99.2Fs0.0Wo0.8), less abundant (~1–11%), up to-1.5-cm sized, homogeneous forsterite (Fo99.9), and highly variable amounts (~1–17%) of sodic feldspar (An2.4Ab95.1Or2.5) set in a fine-grained, comminuted matrix of related material. Less abundant silicates include K-feldspar (An0.1Ab7.0Or92.2) and diopside (En53.5Fs0.1Wo46.4). Opaque phases include Ti-bearing troilite, exotic sulfides such as alabandite, keilite, djerfisherite, oldhamite, caswellsilverite, schöllhornite, and cronusite, Si-bearing (0.7–1.0 wt% Si) and Si-poor (