bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation of satellites around large asteroids
Authors: Walsh Kevin , Ballouz Ronald-Louis , Agrusa Harrison , Hanus Josef , Jutzi Martin , Michel Patrick
Published: July 2024

Known satellites orbiting asteroids larger than ~100 km are found preferentially around primary bodies with rotation periods 5-6 h. This is significantly more rapid rotation than is typical for asteroids this large, which have an average rotation period closer to 10 hours. Similarly, the primaries of the satellite systems are more elongated than average as measured by lightcurve amplitudes and direct imaging. Finally, there are no known satellites around large S-type asteroids.Numerical simulation has found that satellite formation is possible in large collisions between asteroids. However, tracking the shape and spin of the remnant bodies is computationally expensive and has thus not been performed for wide parameter spaces. Therefore, the relationship between impacts that form satellites and remnant spin and shape hasn't been previously utilized for understanding the key physics at play.We present impact models of asteroid collisions typical of the Main Asteroid Belt. A hydrodynamic model of the impact is performed and the outcome is handed off to N-body gravitational models. The N-body modeling is done with pkdgrav, which is capable of modeling granular mechanical interactions. This allows for the evolving shape of the various remnants to be tracked throughout the reaccumulation process. We simulate head-on and oblique impacts into spherical targets that have a range of pre-impact rotation rates.A dynamical stability map for close-in and eccentric orbits is created for each of the simulation outcomes shape and spin. This is used to determine which impact ejecta is placed onto long-term stable orbits as direct outcomes of the impact circumstances. We find that a direct pathway to stable satellites exists for impact outcomes that produce rapidly rotating and elongated remnants. The rapid rotation and elongation can be the result of pre-impact rotation or highly oblique impacts.
Analytical Representation of Saturnian Satellite Numerical Ephemerides over Limited Time Spans
Authors: Xi Xiao Jin , Vienne Alain
Published: July 2024

Numerical integration ephemerides are highly valued in both research and engineering due to their exceptional precision. However, their application in theoretical studies, particularly in the investigation of rotation and evolution, is constrained by their finite available time spans. In our previous work, we effectively explored the analytical representation of the mean longitude of Titan from the Jet Propulsion Laboratory (JPL) ephemeris. We established this representation as a function of combinations of proper frequencies and related the results with what is given in the synthetic ephemerides obtained by the Théorie Analytique des Satellites de Saturne (TASS).In this study, we extend our analytical representations beyond the mean longitude to the other osculating elements of the Titan ephemeris. This allows us to create new synthetic representations that combine the benefits of both systems: the enduring stability and system intricacies of TASS, along with the exceptional precision characteristic of numerical integration ephemerides. These combinations encompass vital dynamical information, including the proper frequencies, which will be valuable for theoretical research. 
Changes of the Physical Properties of Cometary surfaces
Authors: Zou Xiao-Duan , Li Jian-Yang , Becker Kris , Palmer Eric , Gaskell Robert , Domingue Deborah
Published: July 2024

Changes of the Physical Properties of Cometary surfaces Introduction:This is a detailed and comprehensive photometric study on how the physical properties of surface dust cover change at different morphological location on comet 67P/ Churyumov-Gerasimenko and what mechanisms drive these changes. We examined different regolith alteration and dust transportation scenarios in different geomorphological locations and measured the properties with highest resolution sterophotoclinometry (SPC) methods possible. Method:Our technical approach would be to define different geomorphologic units in surface areas with different change level and perform mapping of wavelength-dependent photometric parameters of all units using the OSIRIS-NAC multiband imaging data as archived at PDS/SBN. We followed the procedure as in the previous similar work for 67P [1] and for other asteroids [2, 3] using other missions’ imaging and spectral data to perform photometric modeling and mapping. Once the spectrophotometric parameters and the maps are derived, we compared the differences and similarities between regions and interpret the results in the context of cometary geologic activity history. In this work, we applied a SPC method for generating global and local high-resolution shape models for describing both large scale and small-scale surface changes for multiple locations on 67P. We select our region-of-interests (ROIs) based on the surface change analysis results for further spectrophotometric studies. Then we performed a detailed modeling and mapping of the ROIs, including dramatic change like landslides, and different type of small changes. The error analysis of the modeling results follows the procedure outlined in [2, 4]. Our data products, including geometric backplanes and maps will all be archived to PDS/SBN. Surface Changes:We will report the results and analysis of the surface changes from our methods. And we will also discuss the photometry findings about the changes of the surface physical properties. Acknowledgments:This research is supported by NASA Grant #80NSSC20K1152. All data used in this study are directly downloaded from the PDS small body node. Reference:[1] Zou, X.D., et al., 2021, December. Detailed Geometry Data Study and Photometric Analysis with Rosetta/OSIRIS Images of Comet 67P/Churyumov-Gerasimenko. In AGU Fall Meeting 2021. AGU.[2] Li, J.-Y., et al., 2019. Spectrophotometric modeling and mapping of Ceres. Icarus 322, 144-167.[3] Zou, X.-D., et al., 2021. Photometry of asteroid (101955) Bennu with OVIRS on OSIRIS-REx. Icarus 358, 114183.[4] Li, J.-Y., et al., 2013. Global photometric properties of Asteroid (4) Vesta observed with Dawn Framing Camera. Icarus 226, 1252-1274.
N-bearing complex organic molecules in comet 67P
Authors: Hänni Nora , Altwegg Kathrin , Baklouti Donia , Combi Michael , Fuselier Stephen , De Keyser Johan , Müller Daniel , Rubin Martin , Wampfler Susanne
Published: July 2024

In terrestrial, carbon-based biochemistry, heteroelements such as oxygen, nitrogen, sulfur, and phosphorus play crucial roles as they introduce specific chemical functionalities in organic (hydrocarbon-based) molecules. The debate about the origin and evolution of life on Earth and possibly elsewhere requires a detailed understanding of (1) where and how organic chemical complexity emerges in space and (2) what exogenous materials may have been delivered to the early Earth through impacts, see, e.g., Rubin et al. (2019). Comet studies enable investigation of both aspects as these small bodies possess an organic-rich material record dating back to the earliest history of our Solar System and were an exogeneous contributor of volatile species to Earth (Marty et al. 2017).ESA’s Rosetta mission visited and accompanied comet 67P/Churyumov-Gerasimenko (hereafter 67P) for two years and during a large part of the comet’s orbit around the Sun. Rosetta analyzed the comet’s chemical composition in unprecedented detail. A key instrument was the high-resolution Double Focusing Mass Spectrometer (DFMS) – part of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA; Balsiger et al. 2007). It unveiled a surprising organic chemical complexity: Relying on reference spectra, either calibrated or from the database of the National Institute of Standards and Technology, Hänni et al. (2022) showed how the extremely complex cometary mass spectrum is fully deconvolved. After detailed investigation of the pure hydrocarbon species (Hänni et al. 2022) and the O-bearing organic molecules (Hänni et al. 2023), our current work focuses on the N-bearing compounds. The heteroelement N is common in biomolecules such as amino acids and nucleobases and responsible for their characteristic biochemical functionality. To date, only a few N-bearing complex organic molecules have been identified in comets, one of them being the simplest amino acid glycine (C2H5NO2), which was reported by Altwegg et al. (2016) after a targeted search. Here, we present a non-targeted, full analysis of the N- and NO-bearing complex organics and compare them to N-bearing molecules in meteorites, other comets, and the interstellar medium. Rubin et al. ACS Earth Space Chem. (2019) 3, 1792−1811.Marti et al. Science (2017) 356, 6342, 1069-1072.Balsiger et al. Space Sci. Rev. (2007) 128, 745-801.Hänni et al. Nat. Commun. (2022) 13, 3639.Hänni et al. Astron. Astroph. (2023) 678, A22.Altwegg et al. Science adv. (2016) 2, e1600285.
Near-surface speeds of cometary refractories
Authors: Agarwal Jessica , Lemos Pablo , Pfeifer Marius , Shi Xian , Marschall Raphael
Published: July 2024

When a cometary nucleus approaches the sun, the volatiles sublimate and carry along embedded dust particles. On the first few kilometres this dust is accelerated by the gas drag, while further out, solar radiation pressure and gravity take over, shaping the comets outer coma and tail. While the dust dynamics after leaving the nucleus is reasonably well understood, the emission process as such is not. It is closely related to the way in which dust and ice are intermixed in the cometary surface and how the surface material is structured, which are also not well understood.In recent years, indications from multiple directions have emerged that standard gas drag is not sufficient to accelerate the refractory particles to the speeds measured in the cometary coma, especially for the largest particles emitted. Using different imaging sequences from the Rosetta mission and different analysis techniques, Pfeifer et al. (2024), Lemos (2024) and Shi et al. (2024) find that decimetre- to metre-sized chunks leave the surface or an unresolved region very close to it at speeds of 0.5 – 1 m/s.We review the observational evidence for such a non-zero initial speed and discuss potential implications for understanding the structure and thermophysical properties of the near-surface layers.References:Pfeifer, M. et al. (2024), accepted for publication in Astronomy & Astrophysics, arXiv:2402.18613Lemos, P. et al (2024), accepted for publication in Astronomy & Astrophysics, arXiv:2405.08261Shi, X. et al. (2024), ApJ Letters, 961:L
Titan's elusive clouds seen in polarization
Authors: Cordier Daniel , Wang Zhen , Seignovert Benoît , West Robert A.
Published: July 2024

Titan, the enigmatic large moon of Saturn, is the unique satellite of the solar system surrounded by a dense atmosphere which has a significant effect on radiation polarization. The Cassini exploration of the kronian system has also revealed the existence of large bodies of liquid at the surface of Titan. It is well known that smooth surfaces polarize the reflected electromagnetic waves, that aspect reinforces the interest of a polarimetric study of the Saturn main satellite. On board the Cassini probe, the ISS (Imaging Science Subsystem) instrument was equipped with a large set of spectral and polarized filters that could be combined with one another.By using near infrared filters together with polarized filters, we have searched for features highlighted by polarimetric observations, we have targeted both the surface and the atmosphere. We first worked at the near-infrared wavelength of 939 nm, at which the atmosphere of Titan is slightly transparent. The spectral filter CB3 is then employed with two polarization filters, with perpendicular direction. The resulting polarization maps are interpreted with the help of a multidimensional Monte-Carlo radiative transfer model specifically adapted to Titan’s atmosphere. 
On the Lunar reference systems 
Authors: Rambaux Nicolas , Fienga Agnes , Kaitheri Athul , Gastineau Mickael , Baguet Daniel , Laskar Jacques
Published: July 2024

The future space missions dedicated to the Moon stimulate the renewal of lunar reference system definitions and characterizations. At present, two slightly different reference systems are commonly used to define the lunar body-fixed coordinate system: the Mean Earth/Rotation Axis (or polar axis) (ME) reference system and the principal axis (PA) reference frame.The former has been used at the beginning of lunar observation and it is commonly adopted for archiving and data distribution proposes of lunar surface or topography. The latter corresponds to the orientation where the lunar tensor of inertia is diagonal that is a natural reference system to model and to integrate the equations of motion. It is directly determined from lunar laser ranging measurements. The transformation between the two reference systems (PA, ME) is realised by three static rotations that depends on the lunar gravity field coefficients and dissipative models. Consequently, this transformation is dependent to a lunar ephemeris.In preparation of future lunar missions, we present a review on actual lunar coordinate systems and present a new determination based on the Integration Numérique de l’Observatoire de Paris lunar ephemerides (INPOP) with a determination of a lunar time scale. In addition, we present the expected accuracy and discussed the differences with other lunar coordinate frame realisation. Finally, we provide recommendations for future lunar coordinate system. 
The limits of orbital similarity: meteoroid stream decoherence
Authors: Vaubaillon Jeremie , Shober Patrick , Courtot Ariane
Published: July 2024

Orbital similarity discriminants are an important tool in meteor science for identifying and characterizing meteoroid streams and meteor showers. The degree of similarity between meteoroid orbits is used to identify meteoroid streams and their associations with parent bodies. However, as many previous studies have shown, one must be careful when interpreting such similarity. For example, the widely used $D_{SH}$ criterion is mathematically not sound. In addition, thorough and careful statistical analysis is needed to estimate the probability of random association. Here we estimate the decoherence lifetime of meteoroid streams as a function of orbital elements. This is performed by generating terns of thousands of fictitious meteoroid streams and tracking their coherence over time. First results will be shown.
The Results of ISSI Team #547: Understanding the Activity of Comets Through 67P's Dynamics
Authors: Attree Nicholas , Gutiérrez Pedro , Groussin Olivier , Bürger Johanna , Keller Horst Uwe , Kramer Tobias , Lasagni Manghi Riccardo , Läuter Matthias , Lemos Pablo , Markkanen Johannes , Marschall Raphael , Schuckart Christian
Published: July 2024

Understanding cometary activity gives us an insight into the materials properties, and therefore formation and evolution processes of these relatively pristine protoplanetary objects. We will present the results of an International Space Science Institute project to investigate the phenomenon through the effects of the outgassing activity on the orbit and spin-state of comet 67P/Churymov-Gerasimenko, e.g. its non-gravitational dynamics. This International Team gathered experts in orbital dynamics and trajectory reconstruction together with thermophysical modellers and comet observationalists, in order to compare the available extractions of 67P’s non-gravitational acceleration (NGA) from its trajectory. The team then fitted a combination of the NGA, the non-gravitational torque (NGT), and the total water-outgassing rate with a thermophysical activity model. The results of this model will be presented. In particular, it was found that: non-gravitational forces and torques are driven by water sublimation from the nucleus; thermal inertia and self-heating have only minor effects; spatially uniform activity cannot explain 67P's non-gravitational dynamics; spatially uniform momentum transfer cannot explain 67P's non-gravitational dynamics; and different terrain types have different instantaneous responses to insolation. The implications of these findings for the modelling of cometary material and the variety of surface types seen on 67P will be discussed.
A COMetary dust TAIL Simulator (COMTAILS)
Authors: Moreno Fernando
Published: July 2024

A Monte Carlo computer code useful to generate cometary dust tail images has been developed and will be made publicly available soon. The code can be used to simulate observed dust tail brightness images of any comet, elliptic, parabolic, or hyperbolic, or active asteroid, losing mass as a certain function of the heliocentric distance. The ejected particles are assumed to be distributed following a differential power-law function within a given size range, and are characterized by having a certain geometric albedo and linear phase coefficient. The forces exerted on the particles are limited to the solar gravity and radiation pressure, so that the code is only applicable at nuclear distances when both the gas drag and nucleus gravity forces vanish. The code, written in FOTRAN  language, calls the JPL's Ephemeris Generator to calculate the object positions and orbital elements, and the observation location is set to the Earth, but can be conveniently replaced by any other observation point, such as a spacecraft. Examples of the code execution for several targets along with comparison with existing images will be provided. 
Asteroid photometric and spectroscopic studies with Gaia DR3 data
Authors: Pentikäinen Hanna , MacLennan Eric , Uvarova Elizaveta , Muinonen Karri , Penttilä Antti , Wilawer Emil , Oszkiewicz Dagmara , Cellino Alberto , Tanga Paolo , Wang Xiaobin , Virkki Anne
Published: July 2024

The Gaia Data Release 3 (DR3) contains high-precision sparse-in-time photometric data of more than 150 000 asteroids and spectroscopy of more than 60 000 asteroids (Tanga et al., A&A, 674, A12, 2023). We have fitted simple triaxial and general convex shapes to estimate the rotational periods, spin axes, and linear photometric slopes of the asteroids with the lightcurve inversion algorithm developed by Muinonen et al. (A&A, 642, A138, 2020). Sample selection of the asteroids follows Cellino et al. (A&A, in press, 2024), and we use the ellipsoid results from their genetic evolution algorithm to initiate our ellipsoid and convex shape inversion solutions.
In total, we have modelled linear photometric slopes for 8660 asteroids, which have at least 25 Gaia observations (MacLennan et al., in preparation). The slopes are used to compute H,G1,G2 phase functions (Muinonen et al., Icarus, 209, 542, 2010) to derive absolute magnitudes for the asteroids. As the absolute magnitudes have been calculated using Gaia’s G-band, they account for a larger portion of the incident solar spectrum compared to e.g. V-band. This is particularly useful for estimating the amount of absorbed sunlight for thermal infrared studies of asteroids via calculation of the Bond albedo.
Selecting the asteroids for which there are spectroscopic data as well, gives us 2381 asteroids to analyse further. We have kept the data from the Gaia red and blue photometers (RP and BP) separate due to problems merging them. The wavelength range of both ends have also been cut to eliminate unreliable behaviour in the spectra. We are left with the following wavelengths: 418, 462, 506, 550, 594 nm (in the BP), and 638, 682, 726, 770 nm (in the RP).
We have taken asteroid diameters from NASA’s NEOWISE survey (Mainzer et al., NEOWISE Diameters and Albedos V2.0, 2019) and the absolute magnitudes derived from the lightcurve inversion to calculate geometric albedos for the asteroids. Bond albedos are calculated from the geometric albedo and using the phase integral, q(G1,G2), from Muinonen et al. (Icarus, 209, 542, 2010). Traditionally, geometric albedos have been used to examine the inclusion of asteroids in asteroid families (Masiero et al., ApJ, 770, 7, 2013). Yet, taken together with the mean photometric slope of the families there seems to be a steep inverse linear trend with slopes smaller than 2 mag/rad at α = 20◦.
We now investigate the parameters further by creating bins of the photometric slope and geometric albedo pair using Principal Component Analysis (PCA) on the data of individual asteroids. The asteroid spectra within the bins are examined in order to evaluate how well the parameter pair aids in the classification of asteroids.
Covariance Analysis of the Hera Mission at the Didymos System with the Full Two-Body Problem Dynamical Model
Authors: Gramigna Edoardo , Lasagni Manghi Riccardo , Zannoni Marco , Tortora Paolo , Gaitanas Michalis , Tsiganis Kleomenis , Gkolias Ioannis , Park Ryan S.
Published: July 2024

Hera is a planetary defense space mission led by the European Space Agency (ESA), with a targeted launch in October 2024. Its primary goals encompass a thorough exploration of the Didymos binary asteroid system, marking the assessment of its internal characteristics. Additionally, Hera will meticulously analyze the results of NASA's DART mission's kinetic impactor experiment. The data gathered by Hera promises to be invaluable for any future asteroid deflection endeavors and scientific research, deepening our insights into asteroid geophysics and the evolutionary dynamics of the solar system's formation.In this context, the precise orbit determination of Hera, along with its companion CubeSats Juventas and Milani, will enable the accurate estimation of critical physical parameters. These parameters are essential to determine the momentum enhancement resulting from the DART impact, as well as for analyzing their dynamical state, internal structure, and evolution. Key parameters include mass, mass distribution, gravity, rotational states, relative orbits, and dynamics of Didymos and Dimorphos asteroids.The conventional approach to planetary radio science analysis, which typically treats rotational states as independent variables described by time-dependent polynomials, might not be adequate for interpreting the data collected by the Hera mission. This limitation arises primarily from the anticipated challenge posed by the spin-orbit coupling of the asteroids. Given the irregular shapes and close proximity of Dimorphos to Didymos, a more sophisticated dynamical modeling approach, like the Full Two-Body Problem (F2BP), might be necessary to accurately capture the complex dynamics of the binary system.In this study, we present the Hera orbit determination covariance analysis employing the F2BP model within JPL's Mission Analysis, Operations, and Navigation Toolkit Environment (MONTE) orbit determination software. We show the expected sensitivity to the key scientific parameters, including the gravity field of Didymos, the relative orbit of Dimorphos, the moments of inertia of the bodies, and their rotational states. As the dynamical state of Dimorphos post-DART impact is uncertain, we explore both non-chaotic and chaotic scenarios to evaluate the results' sensitivity to varying conditions. Additionally, we conduct a comparative analysis between the F2BP outcomes and those obtained using standard radio science models.
Probing the Formation Conditions of the Galilean Moons Through Their Differentiation States
Authors: Bennacer Yannis , Mousis Olivier , Monnereau Marc , Hue Vincent
Published: July 2024

The extent of differentiation within the interiors of the Galilean moons remains inadequately determined. Analysis of Callisto's moments of inertia, derived from Galileo's gravity data, suggests its structure lacks full differentiation. Furthermore, a recent reevaluation of the Galileo data casts doubt on the long-standing assumption of Europa possessing a metallic core. Our objective is to elucidate the accretion conditions necessary for the Galilean moons to develop  in a manner consistent with their current state of differentiation. To achieve this, we employ a numerical model simulating the thermal evolution of icy moon interiors throughout their accretion and post-accretion phases. Each moon's embryo undergoes various heating mechanisms, including tidal heating, radiogenic heating, accretional heating from multiple impacts, and heat from the surrounding circumplanetary disk during growth. The magnitude of each heating process is contingent upon the presumed formation trajectory of each moon within the Jovian circumplanetary disk. Consequently, we investigate the accretion scenarios that explain the presence of a partially differentiated moon similar to Callisto and a fully differentiated moon akin to Ganymede. Additionally, we examine the conditions conducive to iron melting and the formation of a metallic core within Europa's context.Figure 1- Temperature distribution inside Callisto, at the end of the accretion. tstart is the time when accretion begins relative to the formation of CAI’s. To avoid melting during accretion, the temperature profile (in black) must remain below the pressure-dependant melting curve for water ice (in red) with 5% ammoniac. For Callisto to accrete partially differentiated, the fraction of fusion φfus in radius must not exceed the 15-20% threshold.
Growing Super Large Sub-Decimeter Pebbles in Protoplanetary Disks: An Erosion Limit for Electrostatic Clustering from Suborbital Experiments
Authors: Penner Jakob , Teiser Jens , Joeris Kolja , Onyeagusi Florence Chioma , Kollmer Jonathan , Wurm Gerhard
Published: July 2024

We conducted experiments with ensembles of colliding sub-millimeter basalt particles under prolonged microgravity conditions on a suborbital flight. In these experiments, the sample motion was excited at different levels. Initial shaking of the particles simulates a classical phase of bouncing in early planet formation. During these collisions, the particles charge, as was measured by applying an electric field. Further moderate shaking then leads to the formation of compact clusters of the charged beads, up to several centimeters in size. These clusters grow by individual impacts up to a velocity threshold of about a meter per second. Beyond that velocity, clusters are eroded. We therefore find a shift in barriers from a bouncing particle at millimeters per second to an eroding cluster at meters per second, going along with a shift in particle size from sub-millimeter up to several centimeters. This allows growth well into a size regime that might make clusters prone to hydrodynamic instabilities and subsequent planetesimal formation.
Chaos maps as tools to explore meteoroid streams dynamics
Authors: Courtot Ariane , Vaubaillon Jérémie , Fouchard Marc
Published: July 2024

Asteroids and comets can both eject streams of meteoroids. If those meteoroids stay on similar orbits and then encounter the Earth, the resulting meteors are visible in our night sky as a series of bright lines seemingly originating from a single point: a meteor shower. If the link between the meteor shower observed and the parent body is definitely proven, any information about the meteor shower can lead to some interesting results on the parent body. This link can be quite complex to establish, as dynamical chaos can play a role in the evolution of meteoroid stream between the ejection from the parent body and the final encounter with the Earth. Dynamical chaos is characterized by the exponential divergence in time of two initially almost identical orbits. In order to study the amount of chaos in meteoroid stream, we have used the well-known method of chaos maps. They are drawn using a chaos indicator, which measures the level of chaos for a specific set of orbital elements. We chose to use the orthogonal fast Lyapunov indicator (see Fouchard et al., 2002). Thanks to these maps, we detect several key features in meteoroid streams. We started by studying the Geminids, the Draconids and the Leonids, three well-known and well-defined meteoroid steams, with widely different orbits (near-Earth orbit, similar to Jupiter-family comet and similar to Halley-type comet, respectively) (see Courtot et al., 2023, 2024). Despite these very different orbital environment, some mechanisms can be found in all three cases: the effect of mean-motion resonances is similar. These resonances with a specific planet capture meteoroids thus preventing them from encountering the planet, forming islands of relative stability. The planets affected by this mechanism are Venus and the Earth for the Geminids, and Jupiter for the Draconids and Leonids. Non-gravitational forces (Poynting-Robertson drag and solar radiation pressure) influence heavily the dynamical evolution of small particles (see Vaubaillon et al., 2005). In the case of the Geminids, we were able to detect the escape of small particles from the capture of mean-motion resonances, but this does not happen for the Draconids and Leonids, because the effect of those forces is much weaker in these regions and the mean-motion resonances are much wider (see again Courtot et al., 2023, 2024).We also studied the Taurids, a less well-known meteroid stream. Here, the link between the supposed parent body of the stream and the observed meteors is not so clear and discussions on the origin of the stream are still ongoing. Despite the similarity with the Geminids in terms of orbits, the Taurids present very different chaos maps, where the effect of mean-motion resonances is much weaker. However, other phenomena can be studied and then compared to the results obtained for the three previous streams. This talk aims to present these results and the next steps on this topic.
Prober Deployment Strategies for Resource Utilization on Small-size Asteroids
Authors: Li Xiangyu , Pan Qian , Qiao Dong
Published: July 2024

Asteroids smaller than 100 m exist extensively in space. They are easy to access and require less energy to land or lift off due to weak gravity, which makes them potential targets for resource utilization or asteroid mining. In the meantime, the small-size asteroids have distinctive dynamical environments due to strong perturbations from solar radiation pressure (SRP) or third-body gravity. Some of the asteroids even have a fast spin rate, which makes significant challenges for probers orbiting or landing on them. In this paper, we investigate the potential prober deployment strategy on small-size asteroids in both orbiting and landing situations. Firstly, the surface environment of the asteroid is discussed. The geometric and geopotential topographies of small-size asteroids are studied under different shape models. The surface escape and lift-off velocities, which determine the minimal tangential and normal velocity to escape the asteroids are studied. Combined with surface terrain, a landing site selection strategy is proposed and the stable regions that are suitable for prober landing are found. It is found that, the stable regions mainly located in the polar region of a faster rotator and gradually extent to middle latitude region as the spin rate decreases. Secondly, in considering the SRP, the orbital environment around small-size asteroids is discussed. The periodic orbits around equilibrium points and terminator/resonant terminator orbits in Augmented Hill Problem are designed. The stability of orbits under high-fidelity model are investigated and the potential parking orbits for prober deployment are found. Deployment and return trajectories to and from the ideal landing site are designed, which could be used as the channel for resource transfer. Finally, due to the uncertain surface parameters, prober might bounce on the surface which causes inevitable deployment errors. The deployment strategy by bouncing control is discussed. The prober reduces its landing error by changing the landing attitude to decrease the bouncing velocity. The strategy could be also applied to the sample transfer on the surface at different landing sites. This paper provides an option for resource exploration and utilization on small-size asteroids.
The impact of flybys on the evolution of solar system analogs, the debris disk systems.
Authors: Roccatagliata Veronica , Kim Min
Published: July 2024

Debris disks represent the last phase of the evolution of protoplanetary disks. As a by-product of the planet formation process, debris disks might host planetesimal belts, dust, and gas.  One of the possible events responsible for the formation and/or evolution of debris disk systems  are flybys. To constrain the influence of encounters in the formation and evolution of debris disks, Bertini et al. (2023) reconstructed the flybys experienced by a statically significant sample of debris disks in the last 5 Myr and predicted for the next 2 Myr. In this talk I will present the sample of 254 debris disks with ages between 2 Myr and 8 Gyr. The Gaia eDR3 position, proper motions and radial velocities have been used to reconstruct the relative linear motions between each debris disk and all possible perturbed in volume of the sky around it. We found that 90% of the analyzed systems have at least a close flyby, implying that the very high incidence of encounters (in particular, close encounters) experienced by the systems in the last 5 Myr. I will also discuss the debris disk systems with known planets, companions and/or flyby(s). It is important to highlight that also our solar system itself experienced at least a close encounter. This implies the fundamental impact of flybys in the evolution of debris disks. The confirmation of the statistical significance of flybys in debris disk systems can also be responsible for stirring of debris material.
An innovative journey through time and space: the 'Time Machines' exhibition
Authors: Duras Federica , Giacomini Livia , Boccato Caterina , Mantovani Giulia , Di Giacomo Federico , Scalise Emanuele
Published: July 2024

We will present the behind the scenes of an expansive astrophysics exhibition, "Time Machines", hosted at the prestigious Palazzo Esposizioni in Rome from November 2023 to March 2024.This was the first large exhibition conceived and realised by INAF, the Italian National Institute for Astrophysics. It offered visitors an extraordinary journey through space and time, all the way to the far reaches of the known Universe, until the dawn of cosmic history, with the help of telescopes, the “time machines” of astronomers and astrophysicists. With a pop style and eighties flair, the exhibition exploited the light travel time – the farther astronomical objects we observe, the further we see back in time – to explore planets, stars and galaxies along an itinerary that is both physical and conceptual. The exhibition was fully bilingual (Italian and English) and included dedicated panels specially designed for primary school children. The creation of the exhibition spanned almost two years, beginning with a core team that included astrophysicists to select the most relevant content, science communicators to make that content accessible, experienced curators of scientific exhibitions and museums, communication experts, and specialists in astronomy education and inclusive practices.‘Time Machines’ integrated various interactive tools to tell the story of modern astrophysics, offering the public unique opportunities for active involvement and discovery. One example is a touch table conceived and designed to offer adults and children the individual and/or collaborative opportunity to touch the Solar System by accessing, visualising and manipulating a series of information boards. Through this exhibit, users could select their favourite planet, explore its characteristics and immerse themselves in a wide range of virtual and multimedia content related to the Solar System. It is also a very useful tool from a didactic point of view, as it goes beyond traditional pen-and-paper teaching methods and facilitates more effective learning for the individual and the class group, creating a playful and stimulating environment. Another example is the virtual tour of the INAF's main observatories. Wearing the virtual reality visor, the viewer is immersed in an immersive and high-impact 360° experience, exploring, while having fun, the key locations of Italian astrophysical research and the main celestial sources studied and observed in these places. Great emphasis was placed on inclusivity, from the sensory planetarium designed for blind people to sound exhibits and sign language guides for deaf people.All this has led to a product that appeals to non-specialist people, capturing also those who are not usually interested in science and manages to create a community around such a complex object as an exhibition.
Risk reduction through managed retreat? Investigating enabling conditions and assessing resettlement effects on community resilience in Metro Manila
Authors: Lauer Hannes , Chaves Carmeli Marie C. , Lorenzo Evelyn , Islam Sonia , Birkmann Jörn
Published: July 2024

Abstract. Managed retreat, a key strategy in climate change adaptation for areas with high hazard exposure, raises concerns due to its disruptive nature, vulnerability issues and overall risk in the new location. On-site upgrading or near-site resettlement is seen as more appropriate and effective compared to a relocation far from the former place of living. However, these conclusions often refer to only a very limited set of empirical case studies or do not sufficiently consider different context conditions and phases in resettlement. Against this background, this paper examines the conditions and factors contributing to community resilience of different resettlement projects in Metro Manila. In this urban agglomeration reside an estimated 500 000 informal households, with more than 100 000 occupying high-risk areas. In light of the already realized and anticipated climate change effects, this precarious living situation exposes families, already socio-economically vulnerable, to an increased risk of flooding. The response of the Philippine government to the vexing problem of informal dwellers has been large-scale resettlement from coasts, rivers and creeks to state-owned sites at urban fringes. However, only very few resettlement projects could be realized as in-city projects close to the original living space. The study employs a sequential mixed-method approach, integrating a large-scale quantitative household survey and focus group discussions (FGDs) for a robust comparison of resettlement types. Further, it reveals community-defined enabling factors for managed retreat as climate change adaptation strategy. Results indicate minor variations in well-being conditions between in-city and off-city resettlement, challenging the expected impact of a more urban setting on resilience. Instead, essential prerequisites for resettlement involve reduced hazard exposure, secure tenure and safety from crime. Beyond these essential conditions, social cohesion and institutional support systems emerge as significant influencers for the successful establishment of well-functioning new settlements. With this findings, the study contributes to the expanding body of literature on managed retreat, offering a comprehensive evaluation based on extensive datasets and providing entry points for the improvement of retreat as a climate change adaptation strategy.
Assessing the key concerns in snow storage: a case study for China
Authors: Wang Xing , Wang Feiteng , Ren Jiawen , Qin Dahe , Li Huilin
Published: July 2024

Abstract. Snow security plays a crucial role in ensuring the success of winter sports events and supporting the ski industry. One effective approach to enhancing snow reliability is through snow storage. Despite its potential benefits, investigations of snow storage in China have been limited. To address this gap, we implemented snow storage covered with geotextiles at two venues, namely the Big Air Shougang (BAS) in Beijing for the Beijing 2022 Winter Olympic Games and the National Biathlon Center (NBC) in Chongli for the Beijing 2022 Winter Paralympic Games, in response to possible extreme meteorological conditions. To assess the key concerns associated with snow storage, ablation (the process of snow loss) and snow properties, we introduced a fine-snow-pile monitoring system and the SNOWPACK model. Our observations revealed that, by 18 February, the snow pile at BAS had lost 158.6 m3 of snow (equivalent to 6.7 % of the initial volume). Subsequently, the accelerated ablation was influenced by meteorological conditions and a thin geotextile layer. Between 16 January and 15 April, the snow pile at BAS experienced a total loss of 1242.9 m3 of snow (corresponding to 52.7 % of the original volume). Regarding snow properties, no significant variations were modeled at the study sites, except for the upper part of the snow piles. Notably, the evaporation of the geotextiles contributed to slowing the ablation process. Consequently, we discourage the use of impermeable coverage schemes for snow storage. Instead, the thickness of the cover played a vital role in preserving the snow pile. At Beijing and Chongli, the 0.7 and 0.4 m thick cover layers, respectively, were found to protect approximately half of the snow pile height over the summer season. Importantly, the evolution of snow properties was consistent across the different cover thicknesses. The findings of our study have implications for the ski industry in China, as they provide valuable insights into snow storage techniques and their impact on snow reliability.
دراسة بعض الخصائص الكيميائية والبكترولوجية للمياه الجوفية ومدى صلاحيتها للشرب بمنطقة قرجي والشارع الغربي-طرابلس
Authors: معيوف كريمة , الشريف ابوبكر
Published: July 2024

يُعد توفير مياه شرب صالحة للاستهلاك البشري من أهم التحديات في ليبيا. تهدف هذه الدراسة إلى تحليل وتقييم مدي صلاحية مياه الشرب في بعض الآبار في منطقتي قرجي والشارع الغربي بمدينة طرابلس. تم جمع (7) عينات من مياه الآبار في المنطقة المستهدفة. شملت هذه الدراسة بعض التحاليل الفيزيائية والكيميائية مثل الموصلية الكهربية، الأس الهيدروجيني، الأملاح الذائبة الكلية، الصوديوم، البوتاسيوم، الكلورايد، الكبريتات، والنترات، بالإضافة إلى التحاليل البكتيرولوجية مثل تعيين العدد الكلي للبكتيريا الهوائية وبكتريا القولون والبكتريا الغائطية. أوضحت النتائج أن قيم الأس الهيدروجيني المتحصل عليها توافق المدي المسموح به من قبل منظمة الصحة العالمية لمياه الشرب، باستثناء البئر رقم (1) حيث بلغت قيمة الأس الهيدروجيني له 6.24 وهي قيمة أقــــل من المعدل المسموح به لحمضيــــة مياه الشرب من قبل منظمة الصحة العالميـــة والتي تتــــراوح بين 6 إلى 7. أما قيم الموصلية الكهربية فتراوحت بين 45.8 الى 4280 مايكروسيمنز لكل سم، وكانت قيم الأملاح الذائبــــة الكلية تتراوح ما بين 29.7 و2840 ملغرم/لتر، وتراوح تركيــــز أيــون الصوديوم من 1.39 إلى 255.7 ملغرم/لتر، وأيون البوتاسيوم من 0.52 الى 33.77 ملغرم/لتر، وأيون الكلورايد من 0.9 إلى 5.5 ملغرم/لتر، وأيون الكبريتات من 1 إلى 99 ملغرم/لتر وأيون النترات من 1.1 الى 14.7 ملغرم/لتر. أما بالنسبة للتحاليل البكتيرولوجية فقد كانت العينات خالية من البكتيريا، باستثناء البئر رقم 4 الذي سجلت فيه أعداد لبكتريا القولون تجاوزت 5000 مستعمرة في اللتر الواحد (500 لكل 100مل). أظهرت مقارنة النتائج المتحصل عليها معملياً أن جميع عينات المياه المدروسة (ما عدا عينات البئرين رقم1 و4) كانت مطابقة للمواصفات القياسية الليبية لمياه الشرب وهي بهذا صالحة للاستهلاك البشري.
Work Posture Analysis using the RULA and OWAS Methods in the Cement Packing Section at the Packing Plant Indarung Unit of PT. Semen Padang
Authors: Fatimah Fatimah , Erliana Cut Ita , Nisa Febriani Aulia
Published: July 2024

PT Semen Padang is a cement manufacturer. According to preliminary observations, the cement packing process, which is done at the Packing Plant Indarung unit, is the last step of the cement production process. Due to the sideways and bowed body positions, cement bagging is performed manually with a less ergonomic working position. This is performed continuously, causing workers complaints of musculoskeletal disorders. The results of distributing the Nordic Body Map questionnaire to employees indicate that many operators experience pain due to their work positions. Based on these findings, the RULA method was used to analyze work posture, yielding a group A posture score of 7, a group B posture score of 4, and a final RULA assessment score of 7. The OWAS method assessment, meanwhile, earned a score code of 2141 and was categorized as a level 3 risk. The results of the risk assessment using the RULA method yield a score of 7, indicating that the operator's work attitude needs to change immediately, whereas the results of the assessment using the OWAS method yield a score of 3, indicating that work posture has a very significant impact on tension and needs to be corrected as soon as possible. On the basis of the results of these assessments, a recommendation was made to design a trolley work facility that can be utilized to reduce the risk of MSDs for cement packaging operators
Cosmetic Shop Sentiment Analysis on TikTok Shop Using the Support Vector Machine Method
Authors: Rahmawati Rahmawati , Fuadi Wahyu , Afrillia Yesy
Published: July 2024

User reviews are crucial in today's digital world for determining a product's quality. Nevertheless, these remarks are frequently disorganized and erratic, which confuses people and makes it challenging for them to make wise purchases. The erratic character of these reviews breeds uncertainty and makes determining a product's actual value more difficult. To help consumers more effectively evaluate and select products on platforms such as TikTok Shop, this study uses sentiment analysis tools. It hopes to accomplish this by improving the overall shopping experience and empowering customers to make more confident and informed selections. This research aims to assist consumers in evaluating and selecting products on TikTok Shop, an online shopping platform, by employing sentiment analysis techniques that help consumers make more informed decisions. In this study, a total of 500 comments from TikTok Shop users were collected as data. 350 comments have been set aside for training and 150 comments were set aside for testing. Data was gathered employing scraping, an automated process that makes use of the Python library's Selenium module to retrieve data from the internet. We employed the Support Vector Machine approach, an efficient machine learning tool for text classification, to assess the comments. 121 comments were categorized as having positive sentiment and 29 as having negative sentiment based on the test results. The system successfully recommended the "Ourluxbeauty" cosmetics store as a shop with many positive sentiments, indicating a recommendation level of 0.7 on the positive sentiment scale. The system's accuracy was measured using a Confusion Matrix, resulting in an accuracy rate of 78% and an inaccuracy rate of 22%. This demonstrates that the system can accurately classify comment sentiments and has significant potential for application in e-commerce practices to enhance the online shopping experience.
POSSIBLE CONFISCATION OF RUSSIAN STATE ASSETS IN THE WEST: LEGAL AND POLITICAL ZUGZWANG
Authors: Shevtsov A.L.
Published: July 2024

The paper examines the prospects for the possible confiscation of state assets of the Russian Federation in favor of Western countries. The case of confiscation of private assets is briefly considered. The precedents of the confiscation of sovereign assets are analyzed. The legal inconsistency of the intentions to confiscate Russian assets has been demonstrated. Despite the fact that Western countries are actively working on a regulatory solution to the issue, it is shown that the implementation of such a scenario carries serious risks to the international monetary system, can act as a driver of significant erosion of the Bretton Woods system and dollar hegemony in general. In this situation, any action, as well as inaction, leads to a deterioration of the situation, which refers us to the title of the article, causing an association with zugzwang.