Cassini observations of the micrometeoroid bombardment flux, ring mass and fractional pollution constrain the origin and history of Saturn’s rings. In the simplest model, the age of the rings can be estimated by assuming the rings are a closed system with constant bombardment at the current rate. Observations during the Cassini Grand Finale orbits provide some challenges for this assumption. Further, the remote sensing of the rings shows a red slope, with higher pollution at the shortest wavelengths, consistent with reddening due to space weathering of atmosphereless bodies. If processes at the time of the micrometeorite impacts or subsequent chemical and physical weathering can degrade the original pollutants, this means that laboratory spectra are not appropriate to determine the total extrinsic material that has struck the rings over its lifetime. Rosetta data on the dust composition and surface reflectivity of Comet P67 provide our starting point for the composition of the bombarding material. Laboratory results for irradiation of icy outer solar system analogues indicate oxidation of organics and other pollutants over time. It is now generally agreed that the radiolysis of ice by energetic ions, electrons and solar UV photons produces the oxygen, ozone and peroxide seen at many icy satellites. The porosity of ice provides sufficient space for chemical reactions and mobility (Li 2022). The ring particle surfaces are in addition continually gardened by particle collisions and meteoritic impacts. Because of these loss processes, the current fractional pollution provides only a lower limit on the total integrated pollution flux, and thus a lower limit for the ring age. Two independent analyses of Cassini UVIS spectra of Saturn’s rings give fractional pollution in the outer B ring of 2-3%. This provides a lower limit of 400 to 1600 million years for the most opaque parts of Saturn’s B ring, depending on whether we use the maximum or minimum values for the bombardment rate reported by Cassini CDA (Kempf 2023). The A and C rings, as well as other ring structures, may be younger, having formed more recently.

How to cite: Esposito, L. W., Elliott, J. P., and Bradley, E. T.: Space Weathering Provides a Lower Limit on the Age of Saturn’s Rings, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13303, https://doi.org/10.5194/egusphere-egu24-13303, 2024.

Hypervelocity (>1 km/s) dust grains orbiting in the inner heliosphere can collide with a spacecraft and create a plasma cloud that changes electrical conditions in the surrounding plasma. These changes can be detected by the onboard radio and plasma wave receivers acting as efficient dust impact detectors. Estimated dust impact rates depend on the observation time window and they are commonly extrapolated. Our study presents the RPW/TDS Maximum Amplitudes (MAMP) data that continuously monitors signals from up to four RPW antenna configurations (monopole or dipole, and HF Search Coil) onboard the Solar Orbiter satellite. The signal is sampled in the high cadence (2.091 Msps) and stored in a buffer as the absolute maximum amplitude. MAMP values are then provided with a cadence between 32 and 128 sps, giving us a time resolution between 8 and 31 ms. Individual dust impacts detected by the onboard algorithm evaluating 62ms-long waveform snapshots every second are compared with the MAMP observations and show a very good match. After corrections for the high amplitude plasma waves or non-standard operational modes, and together with the TDS Statistics, the MAMP observations are used for the individual dust impact identification and corrected impact rates during the entire Solar Orbiter mission.

How to cite: Píša, D., Souček, J., Kočiščák, S., Kvammen, A., Vaverka, J., Formánek, T., Santolík, O., Morooka, M., Maksimovic, M., and Zaslavsky, A.: Continuous monitoring of dust impacts across the inner heliosphere by the Solar Orbiter RPW/TDS Maximum Amplitudes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8518, https://doi.org/10.5194/egusphere-egu24-8518, 2024.

Comet Interceptor is an European Space Agency (ESA) mission in cooperation with the Japan Aerospace Exploration Agency (JAXA). It aims to characterise through a close flyby a long period comet, preferably dynamically new, or an interstellar object. The main spacecraft will be accompanied in its encounter with the target comet’s nucleus by two small probes, one provided by Europe, and the other by Japan. The mission is planned for launch in 2029. Its Science Working Team (SWT) is supported in specific scientific and science operation areas by Working Groups (WGs). These are the Target Identification WG and Comet Environment WG. The latter comprises three sub-WGs, covering the Nucleus, Near-Environment, and Far-Environment. Here, we provide a brief overview of the mission, and present and describe the aims and activities of the working groups. The search is already underway for potential comets to encounter, and preparations are being made for the scientific exploitation of the data from the mission’s three spacecraft.

How to cite: Jones, G., Snodgrass, C., Guilbert-Lepoutre, A., Vincent, J.-B., Goetz, C., Martellato, E., Sugita, S., and Kueppers, K.: Activities of the Comet Interceptor Comet Environment and Target Identification Working Groups, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22216, https://doi.org/10.5194/egusphere-egu24-22216, 2024.

How to cite: Haslebacher, N., Thomas, N., and Marschall, R.: Spectral ratioing of Afρ to constrain the particle size distributions of comets, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11065, https://doi.org/10.5194/egusphere-egu24-11065, 2024.

Gritsevich et al. (2022) studied the evolution of a dust trail from the massive outburst of comet 17P/Holmes in October 2007. They predicted that ground-based telescopes could observe this dust trail in 2022 and the subsequent observations were successfully conducted. The observations of the dust trail provide a valuable opportunity to study many peculiarities of the comet, including its activity, structure, and characteristics of the released dust particles. In the present work, we study dynamic evolution of the particles after a long period of time. We investigate the potential for a collision with Earth, Moon, and other celestial bodies; instants of high concentration of particles in the dust trail, and how the solar radiation pressure affects the dynamics of the dust. Recently, comet 12P/Pons-Brooks has experienced a series of well-documented outbursts during its current approach to perihelion, making it an exciting case for investigation. We simulate the evolution of dust particles released by the outbursts of comet 12P/Pons-Brooks during 2023. We use the software REBOUND for the simulations, integrating with the IAS15 numerical integrator. We initiate a system with the Sun, Venus, Earth, Moon, Mars, Jupiter, Saturn, Uranus, and the comet itself at the outburst date for the simulation. The results of the simulations are detailed and analyzed throughout the work.

References

Maria Gritsevich, Markku Nissinen, Arto Oksanen, Jari Suomela, Elizabeth A Silber, Evolution of the dust trail of comet 17P/Holmes, Monthly Notices of the Royal Astronomical Society, Volume 513, Issue 2, June 2022, Pages 2201–2214, https://doi.org/10.1093/mnras/stac822

How to cite: Borderes Motta, G., Kastinen, D., Kero, J., and Gritsevich, M.: Comet 12P/Pons-Brooks' Dust Fate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18373, https://doi.org/10.5194/egusphere-egu24-18373, 2024.

Comet surfaces have a complex morphology on large scales (such as pits, depressions, scarps and faults) as well as on small scales (such as particle size, porosity distribution and roughness of the comet surface). Little is known about the influence especially of small-scale structures on the gas-flow and the ability to lift off dust particles. Focusing on small-scale structures, we simulate diffusion processes applying Fick's law. For the upper and lower boundary of the simulated box, a flat sublimation front with constant pressure below the inactive surface layer and a perfect vacuum on the surface is assumed. By applying periodic boundary conditions in the planar direction, we mimic an infinite surface with periodic inhomogeneity. We performed the simulation with different variations of diffusivity. In one example, the simulation shows that a region of high porosity within a region of low porosity experiences an increase in the flow rate, as would be expected according to Fick's Law. Nevertheless, it also significantly changes the flow rate in the surrounding region due to lateral flows in the vicinity of the high diffusivity region. We analyze the results qualitatively and compare them with 3D Monte Carlo simulations in a similar setting, which shows a general agreement.

In addition, we conduct experiments with a dedicated vacuum-chamber to measure the viscous permeability and Knudsen diffusion of granular materials by applying the binary friction model. The design allows measurements in different gas-flow regimes, with most samples mainly covering the free molecular flow and the transition region. In the last measurement campaign, bi-disperse samples of spherical particles were measured and the results show a good agreement with generalized models depending on the specific surface area of the sample. The current measurement campaign focuses on angular materials and the influence of shape properties on diffusivity. The results show that packings of highly porous hollow cylinders have a lower diffusivity than expected compared to more compact packings of spherical particles. A comparison with Monte Carlo simulations (from [1,2]) of packings of highly porous spherical particles also shows a higher diffusivity compared to the same measurements. Further measurements will show whether a dependence on a particular shape property could explain this discrepancy.

[1] Macher, Wolfgang, et al. "Transmission probability of gas molecules through porous layers at Knudsen diffusion." Journal of Engineering Mathematics 144.1 (2024): 1-26.

[2] Güttler, Carsten, et al. "Simulation and experiment of gas diffusion in a granular bed." Monthly Notices of the Royal Astronomical Society 524.4 (2023): 6114-6123.

How to cite: Zivithal, S., Kargl, G., Macher, W., Güttler, C., Gundlach, B., Sierks, H., and Blum, J.: Studying gas flow on cometary surfaces with diffusivity variations using flow simulations and experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15837, https://doi.org/10.5194/egusphere-egu24-15837, 2024.

Estimating the probability of a collision of asteroids with the Earth is an important task for planetary defense. There are systems that compute impact probabilities of near-Earth asteroids with the Earth on a regular basis: Sentry (Nasa, Jet Propulsion Laboratory) and CLOMON-2 (originally University of Pisa, now ESA). Here we present NEOForCE (Near-Earth Objects Forecast for Collisional Events) a new monitoring system developed at Institut de mécanique céleste et de calcul des éphémérides (IMCCE, Paris Observatory). This system is original and independent. As ephemeris of major planets and the Moon we use INPOP [1]. The asteroids’ orbits and covariance matrices are taken from DynAstVO database [2]. For computing the impact probability we use the Line Of Variation (LOV) sampling method [3] but with significant modifications. The longest axis of the confidence ellipsoid is chosen to be sampled obtaining virtual asteroids. Each virtual asteroid’s orbit is propagated from the time of discovery 100 years ahead with variational equations. Each virtual asteroid is a representative of its small vicinity and we apply the Partial Banana Mapping method (PBM) [5] for each of this vicinity to look for possible collisions. Then the results are combined and the procedure to find explicitly the initial conditions of the collisional trajectory is launched.

The main differences with the existing monitoring systems are: usage of INPOP ephemeris of major planets instead of DE, having our own orbit fitting and propagation procedure of asteroids from DynAstVO, and implementation of Partial Banana Mapping method. Hence the system provides an independent assessment of the impact probability, which in case of risks is crucial.

[1] Fienga, A., et al. (2020) INPOP new release: INPOP19a. Astrometry, Earth Rotation, and Reference Systems in the GAIA era. p. 293-297.

[2] Desmars J., et al. (2017) DynAstVO: a Europlanet database of NEA orbits. European Planetary Science Congress. 2017. p. EPSC2017-324.

[3] Milani A., et al. (2005) Nonlinear impact monitoring: line of variation searches for impactors. ICARUS, V. 173, p. 362-384.

[4] Vavilov D.E. (2020) The partial banana mapping: a robust linear method for impact probability estimation. MNRAS, V. 492, p. 4546–4552.

How to cite: Vavilov, D. and Hestroffer, D.: Near-Earth Objects’ Forecast of Collisional Events (NEOForCE). Impact monitoring system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19273, https://doi.org/10.5194/egusphere-egu24-19273, 2024.

On 26 September 2022, NASA's Double Asteroid Redirection Test (DART) mission impacted Dimorphos, the moonlet of near-earth asteroid (65803) Didymos, performing the world's first planetary defence test. ESA's Hera mission will be launched in October 2024 and rendezvous with the Didymos system end of 2026 or beginning of 2027. It will closely investigate the system and in particular the consequences of the DART impact.  

Hera carries the hyperspectral imager Hyperscout-H. Its sensor consists of 2048 x 1088 pixels which are arranged in macro pixel blocks of 5 x 5 pixels. The 25 pixels of each block are covered with filters in 25 different wavelengths where the center response ranges from 657 to 949 nm. Therefore, each of the 2048 x 1088 pixels provides only the brightness information for one wavelength and hence the theoretical 2048 x 1088 x 25 data cube is only sparsely populated. 

A simple straight forward approach to replenish the sparse data cube would be to move a 5 x 5 pixel window with one pixel steps horizotally and vertically over the whole frame and assign the obtained 25 wavelength spectrum to the center pixel of the window. Besides reducing the image resolution to the quite coarse macro pixels, the accuracy of this method is limited by pixel to pixel variations of the spectra and even more by varying albedo and shading effects caused by varying surface inclination. This makes the resultant spectra very noisy. 

In order to retrieve more accurate spectra with higher spatial resolution, we separate the spectrum at each micro pixel into a normalized spectrum and a brightness scaling factor. We assume the normalized spectra to be spatially smooth, but not necessarily the scaled spectra. Ratios of measured values are used to iteratively compute the normalized spectral value from adjacent pixels. After convergence, the spectra are brightness scaled to reproduce the measured values. This approach allows to replenish the complete data cube with full micro pixel resolution. The application to test images shows that spectra are recovered much more accurately than with the direct approach and that only very little spatial detail is lost. 

Having replenished the complete data cube allows us to construct color images at full micro pixel resolution. The three colors are sufficient to capture most of the spatial variation of the spectra of asteroid surfaces and hence the constructed color images provide a concise visualization of the respective full data cubes. 

How to cite: Grieger, B., de León, J., Goldberg, H., Kohout, T., Kovács, G., Küppers, M., Nagy, B. V., and Popescu, M.: Superresolution color images from the sparse data cubes of the Hyperscout-H hyperspectral imager aboard the Hera mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19491, https://doi.org/10.5194/egusphere-egu24-19491, 2024.

Tidal theory in binary asteroids is in a low state of development in comparison to that of planetary satellites. The dissipative processes within binary secondaries are divergent from the processes at work in planetary satellites, and also the evolutionary timescales are drastically shortened. To study the tidal torques and the spin evolution of the smaller secondaries in binary asteroid systems, it is believed to still be possible to apply a viscoelastic theory somewhat analogous to the models used for planetary satellites (see e.g. Murray & Dermott 1999). If this is true, then there should exist body-averaged “bulk” material properties, such as rigidity and viscosity, applicable for these models. Importantly, it should be possible to compute effective k2 (tidal potential Love number) and Q (quality factor) values for these tiny worlds.

Some pioneering works have derived first-order tidal laws for binary asteroids via analytic and semi-analytic methods. Nimmo & Matsuyama (Icarus 2019) derive a friction-driven effective quality factor Q which decreases (i.e. more dissipation) with stronger friction. Goldreich & Sari (The Astrophysical Journal 2009) argue that effective rigidity is dynamically dominant, deriving an important law for effective k2 for asteroids that scales linearly with the asteroid radius. They also argue that effective Q could be quite low for asteroids, lower than prior estimates of Q ~10². By contrast, Efroimsky (The Astronomical Journal 2015) argues that effective viscosity is dominant and rigidity doesn’t matter. Recently, Pou and Nimmo (Icarus 2024) showed that k2/Q values implied by the ages of some binary asteroids are much lower than the values predicted by Goldreich & Sari (2009), suggesting that the theory of the latter is incomplete.

In this work, we follow up on the aforementioned theoretical works with numerical experiments of binary asteroid tidal evolution, which have strong scientific motive to be carried out. This is accomplished using the massive N-body simulation architecture of GRAINS (Ferrari et al, MNRAS 2019), wherein gravitational, contact, and frictional effects are modeled in the interaction of thousands of non-spherical mass elements. We initialize a simplified binary system analogous somewhat to the scenarios employed in Agrusa et al (PSJ, 2022). To facilitate tidal locking, the static moment-of-inertia asymmetry is made sufficiently large, the secondary is initialized in a state of slightly super-synchronous rotation, and inter-element friction is enhanced, if needed, to yield a dissipation timescale in line with our numerical capabilities (a move inspired by the approach of Goldreich, The Astronomical Journal 1966). From our simulation results, we perform the following analysis:

• A simple regression analysis infers the effective k2/Q from the computed rotational energy dissipation rate, via parallel application of the classical 1D MacDonald tidal dissipation model.
• Previously derived scaling laws for effective k2 and Q are tested.
• The accuracy of the MacDonald tidal torque model for binary rubble pile asteroids is tested.
• With time permitting, if the (unimodal) MacDonald tidal model is shown to be inaccurate, we'll explore computation of an appropriate multimodal tidal potential, as in Darwin-Kaula theory.

How to cite: Burnett, E., Fodde, I., and Ferrari, F.: Numerical inference of viscoelastic properties in tidal models of rubble pile asteroids, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17927, https://doi.org/10.5194/egusphere-egu24-17927, 2024.

Asteroids are originated by the evolution of the disk in the Solar System and, in general, do not have spherical and symmetrical shapes. The reason for those irregular shapes is the small mass of the bodies, such that gravity is not sufficient to make them reach a spherical shape. Those irregular shapes make the study of spacecraft orbits to investigate those objects  complex. Adding this to the fact that their weak gravitational field allows forces that are usually negligible or of second order  for spacecraft near a massive body (e.g.,  solar radiation pressure) to be comparable to the gravitational forces, provides an interesting and important problem to be studied in terms of astrodynamics. The study of asteroids is important because they carry essential scientific information about the origin and evolution of the Solar System. For all these points, it is important to understand their motion and investigate the motion of a spacecraft close to the asteroid. Asteroids may exist alone or in groups of two or three. Recent observations show that binary asteroids could be even more common than we think. In that sense, the present research focused on studying the orbital evolution of a binary asteroid system with almost equal masses composed of two non-spherical asteroids tidally locked that are close to each other, and the dynamical evolution of spacecraft orbiting the system. Since Keplerian orbital elements are not always a good approach for spacecraft in high mass ratio binary systems, to study this problem, we consider the mathematical models of the planar full two-body-problem for the binary asteroid, and the circular restricted three-body problem for the spacecraft, adding ellipsoidal geometry to represent the non-spherical shapes of the binary in order to find natural stable solutions. We also analyzed the structure of the phase space and the importance of the effect of solar radiation pressure on this dynamics. We studied the dynamics and the effect of the gravitational shape of close binary systems in their mutual orbits, as well as the existence of spacecraft circular and resonant orbits. As an application of this research, we studied the binary system Antiope 90. We found stable, close direct and retrograde orbits for the jacobi constants between -1.1 and -0.5; and internal resonant retrograde orbits within the primary and the secondary for the energy -0.7. The majority of the dynamical structure has survived over 90 days assuming the effects of solar pressure radiation.

How to cite: Caritá, G., Hussmann, H., Prado, A. F. B. D. A., Callegari, N., Morais, M. H. M., and de Carvalho, R. E.: Planar dynamics of non-spherical close tidally locked binaries asteroids , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9846, https://doi.org/10.5194/egusphere-egu24-9846, 2024.

Current evidence shows that most asteroids are rubble piles, which are defined to be aggregates of loosely consolidated material bound by gravity and likely a small amount of cohesive strength. Rubble-pile asteroids are granular systems, which can be reshaped through external excitation like meteoritic impacts, the YORP effect, and planetary encounters. Universal modelling of granular systems is one of the major unsolved topics in physics, as these systems are chaotic, multi-scale, and highly dependent on the non-linear interactions between its constituent particles. These difficulties are exacerbated as the low gravity invalidates some terrestrial observations and scaling laws.

Most analytical models are based on continuum mechanics, like the Mohr-Coulomb or Drucker–Prager criterion, fitted to specific sets of observations. These models are able to explain certain aspects of the asteroid population well, but are not able to accurately describe all their critical properties and are furthermore not dynamical. On the other hand, numerical simulations have shown a great potential to predict the evolution of these systems, down to properties of their individual fragments. However, their high computational burden and sensitive dependency on initial conditions make it harder to generalise conclusions made from them.

This work tries to bridge the gap between numerical and analytical modelling of rubble pile asteroids, by using the data produced by numerical simulations to derive a set of analytical equations of motion. Machine learning based system identification methods like genetic programming or neural networks have been shown to work well in predicting complex non-linear dynamical systems. However, key properties of good analytical models, like interpretability and generalizability, are often neglected by these methods. For this reason the sparse identification of non-linear dynamics (SINDy) method was developed, which avoids this problem by applying a sequential thresholding least-squares algorithm on a set of mathematical functions to obtain a sparse representation of the dynamics. 

In this work, first a set of time series data is obtained from the numerical code GRAINS, which is an N-body code that takes into account the complex shape of the individual particles, as they interact through self gravity and contact. A set of macroscopic state and environment variables are selected, which can either be physical values like the moments of inertia and/or spin-up rate, or numerically derived optimal coordinates (using e.g. proper orthogonal decomposition). This time series data is then used by SINDy to obtain a symbolic representation of the time derivative of the state variables. The thresholding parameter of SINDy can be tuned to obtain either a simpler model that mainly qualitatively describes the system, or a more complex model that also has a good quantitative performance. These analytical models are then used to obtain various dynamical properties of the systems, e.g. equilibrium points, bifurcations, etc.

This research shows how the data obtained from simulations can be used to obtain a parsimonious model for the dynamics of rubble pile asteroids. These models can further improve our understanding of the origin and evolution of rubble-pile asteroids, and help inform and interpret future observations.

How to cite: Fodde, I. and Ferrari, F.: Discovery of Rubble-Pile Asteroid Dynamics through Sparse Symbolic Regression, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4652, https://doi.org/10.5194/egusphere-egu24-4652, 2024.

Jupiter-family comets (JFCs) originate from the Kuiper belt and scattered disk, characterized by short orbital periods and frequent interactions with Jupiter. Their icy composition and a chaotic transition to the inner solar system result in short dynamic and physical lifetimes. These features make JFCs key subjects for understanding the migration of celestial bodies and possibly the delivery of organic materials to the early Earth. Numerous studies of fireballs have historically posited a substantial contribution of large objects from JFC orbits, suggesting a significant presence of cometary material in the near-Earth environment. However, this prevalent belief necessitates a thorough re-examination, as the physical evolution of comets and the mechanisms governing their disintegration remain subjects of debate. Understanding the population of meteoroids and comets is crucial for evaluating this population's physical breakdown and evolution. Current dust models suggest that fragmentation and disintegration of comets play a significant role in populating the zodiacal cloud. However, the larger centimeter-meter scale debris observed by fireball networks has been shown to resemble more asteroidal sources dynamically, indicating that comets might be breaking down directly only into dust-sized fragments. 

This study extends the scope of existing research by conducting a detailed analysis of both JFCs and comet-like fireball observations, aiming to elucidate the origins and dynamics of objects on JFC-like orbits across varying size scales. Utilizing extensive data from four major fireball networks (DFN, EFN, FRIPON, MORP) and ephemeris data of JFCs, the research comprises 646 fireball orbits and 661 JFCs. Methods include orbital stability analysis over 10,000 years, Lyapunov lifetime estimation, debiased NEO model source region estimation, meteorite fall identification, and meteor shower analysis.

The analysis reveals that most meteoroids on JFC-like orbits do not align dynamically with typical JFCs. Instead, they predominantly originate from stable orbits in the outer main asteroid belt, challenging the notion that centimeter-to-meter scale meteoroids on JFC-like orbits primarily derive from JFCs. Furthermore, a subset of 24 JFCs in near-Earth orbits displayed unexpected orbital stability, suggesting a presence of asteroidal interlopers from the outer main belt within the JFC population.

Our study demonstrates significant dynamical differences between kilometer-scale JFCs and smaller meteoroids. While the larger JFCs frequently encounter Jupiter and have dynamic, transient orbits, the smaller meteoroids detected by fireball networks originate primarily from stable orbits, indicating a predominant influence of asteroidal material from the outer main belt. This finding challenges conventional assumptions about the origins of JFC-like debris observed on Earth and highlights the complexity and diversity of the small-body environment in our solar system.

How to cite: Shober, P., Vaubaillon, J., Tancredi, G., Devillepoix, H., Sansom, E., Deam, S., Anghel, S., Colas, F., and Martino, S.: Unraveling the Origins of JFC-like Bodies: A Comparative Study of Comets and Meteoroids, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3147, https://doi.org/10.5194/egusphere-egu24-3147, 2024.

We have a long-term goal of creating a holistic and cross-disciplinary approach to meteor research where we connect together topics such as meteor measurements, ablation simulations, meteoroid stream simulations, and sensor simulations. Here, we present the most recent work on developing an automated radar data analysis algorithm able to calculate probability distributions of meteor- and meteoroid parameters for head echoes measured using interferometric high-power large-aperture radars. The algorithm utilizes direct Monte Carlo simulations of uncertainties, with Bayesian Markov-chain Monte Carlo estimation of meteor model parameters. The algorithm also employs N-body propagation of distributions to perform orbit determination, estimating the galactic background noise temperature for absolute-calibration and an statistical approach using many high signal-to-noise ratio meteors for phase calibration. This analysis algorithm has been applied to data from the Middle and Upper atmosphere (MU) radar in Shigaraki, Japan. As a first case study, we have re-analysed a part of the MU radar meteor head echo data set collected during 2009-2010. As a result we have confirmed the existence of a rare high-altitude radar meteor population with initial altitudes reaching up to ~150 km. Out of the total amount of 106 000 events, only 74 had an initial altitude >130 km, while four of those had an initial altitude >145 km.

How to cite: Kastinen, D. and Kero, J.: High-altitude radar meteors detected using a new analysis algorithm for interferometric meteor head echoes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18828, https://doi.org/10.5194/egusphere-egu24-18828, 2024.

This study addresses the challenge of visually identifying meteorites from terrestrial rocks, traditionally a task for experts followed by chemical analysis. We propose a transformative approach using computer vision and machine learning, employing YOLO (You Only Look Once) object detection algorithms (versions 5, 6, 7, and 8), to overcome the bottleneck in expert availability for instantaneous classification. Leveraging a curated selection from the Sharjah Academy for Astronomy, Space Sciences, and Technology (SAASST) unique meteorite collection, we aim to differentiate meteorites from terrestrial rocks based on their surface features and characteristics. The collection comprises a diverse assemblage of approximately 8,000 objects such as iron meteorites, Martian meteorites, tektites, fulgurites, and more. Our methodology includes a comparative analysis of YOLO versions, focusing on precision, recall, and F1 scores to assess each algorithm's adaptability to the unique features of meteoritic material. Preliminary results indicate YOLOv5 as the most efficient compared to its previous versions, achieving a maximum mAP of 0.995 and correctly classifying 93% of test samples. This study aims to determine the optimal YOLO version for enhancing the accuracy and efficiency of meteorite classification. In addition, the selected optimal model will be deployed on a Jetson Nano processor aboard a drone, significantly enhancing onsite meteorite detection capabilities.

How to cite: Alowais, A., Alkhalifa, M., Subhi, S., and Fernini, I.: Advanced Meteorite Identification through YOLO Object Detection Algorithms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14995, https://doi.org/10.5194/egusphere-egu24-14995, 2024.

This research aims to investigate iron meteorites samples, in terms of their elemental composition, distinguished structure, and their role in enhancing our understanding of the early solar system astrophysical processes. Iron meteorites represent a distinctive category of extraterrestrial materials, provide valuable insights into the formation and composition of asteroids, and the historical evolution of the early solar system around 4.6 billion years ago. Physical tests, including magnetism, fusion crust, density, and the window test, were performed on 140 samples from 2017 to 2023, with 161 analyses being carried out.  In addition to that, the study sheds light on the metallic phases of an oriented intergrowth of kamacite and taenite bands, revealing their occurrence in a unique Widmanstatten pattern. This pattern is visible on the studied samples that have been cut, polished, and etched with a weak, nitric acid. This remarkable pattern provides essential information for unraveling the thermal and cooling histories of these celestial bodies. Advanced analytical techniques such as X-ray fluorescence (XRF), and X-ray diffraction (XRD), were employed to identify the mineralogy and chemical composition of a diverse array of specimens. Iron-nickel minerals such as Kamacite are commonly found in the studied samples as well as the presence of troilite (FeS) inclusions, and traces of other elements. Of the 140 samples, three samples from different countries were identified as iron meteorites, allowing for a nuanced exploration of their unique characteristics. The chemical composition and mineralogy of the samples, revealed by the mentioned techniques, lead us to conclude that these samples formed at the core of asteroids or fragmented planets. This research contributes significantly to the UAE’s planetary science program and enriches meteoritic studies for university students and researchers in this field.

How to cite: Subhi, S. and Alowais, A.: The Mineralogy and Unique Widmanstatten Pattern in Iron Meteorites, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2750, https://doi.org/10.5194/egusphere-egu24-2750, 2024.

The identification of meteorite parent bodies provides the context for understanding planetesimal formation and evolution as well as the key solar system dynamical events they have witnessed. We identified that the family of asteroid fragments whose largest member is asteroid (161) Athor is the unique source of the rare EL enstatite chondrite meteorites (Avdellidou et al. 2022), the closest meteorites to Earth in terms of their isotopic ratios. The Athor family was created by the collisional fragmentation of a parent body 3 Gyr ago in the inner main belt (Delbo et al. 2019), however the diameter of the Athor family progenitor was much smaller than the putative size of the EL original planetesimal (Triellof et a. 2022). Therefore, we deduced that the EL planetesimal that accreted in the terrestrial planet region underwent a first catastrophic collision in that region, and one of its fragments suffered a more recent catastrophic collision in the main belt, generating the current source of the EL meteorites. 

We investigated the possible ways that could have brought the Athor family progenitor in its current position in the inner main belt. To do so, we used an interdisciplinary methodology where we combined laboratory meteorite thermochronometric data, thermal modelling, and dynamical simulations. 

We showed that planetesimal fragments from the terrestrial zone must have been implanted into the main asteroid belt at least 60 Myr after the beginning of the solar system. We concluded that the giant planet instability is the only dynamical process that can enable such implantation so late in the solar system timeline. 

Acknowledgements. We acknowledge support from the ANR ORIGINS (ANR- 18-CE31-0014). This work is based on data provided by the Minor Planet Physical Properties Catalogue (MP3C) of the Observatoire de la Côte d’Azur (mp3c.oca.eu).

References:

Avdellidou, Delbo, A. Morbidelli, Walsh, Munaibari, Bourdelle de Micas, Devogèle, Fornasier, Gounelle, & van Belle. Athor asteroid family as the source of the EL enstatite meteorites, 2022, A&A, 665, id.L9, 13 pp.

Delbo, Avdellidou, & Morbidelli, Ancient and primordial collisional families as the main sources of X-type asteroids of the inner main belt, 2019, A&A, 624, A69 

Trieloff, Hopp & Gail. Evolution of the parent body of enstatite (EL) chondrites, 2022, Icarus, 373, 114762

How to cite: Avdellidou, C., Delbo, M., Nesvorny, D., Walsh, K., and Morbidelli, A.: Enstatite chondrite meteorites date the giant planet instability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20327, https://doi.org/10.5194/egusphere-egu24-20327, 2024.

Cosmic objects, predominantly small meteoroids, frequently interact with Earth's atmosphere, and often go undetected due to their small size. Thus, to better understand the nature of these objects, we need to deploy networks of detectors which track their atmospheric disintegration [1]. This study delves into techniques for measuring the pre-atmospheric mass of meteoroids with known trajectories, some of which were the subject of successful meteorite recovery campaigns. Among the studied methods, we found that the radiated light of the meteoroid disintegration is the most reliable method of estimating its kinetic energy and pre-atmospheric mass [2]. This relation in combination with currently expanding fireball networks [3] can be used to calibrate other methods of estimating the objects mass (e.g. radio, infrasound). Ultimately, by constraining the size and frequency of small meteoroids, we can make inferences about the formation, evolution, and distribution of small objects and debris in the Solar System.

References:

[1] Colas F. et al. (2020) Astronomy & Astrophysics 644:A53.  [2] Anghel S. et al. (2021) Monthly Notices of the Royal Astronomical Society 508:571. [3] Vida D. et al. (2021) Monthly Notices of the Royal Astronomical Society 506:5046.

How to cite: Anghel, S., Birlan, M., and Nedelcu, D.-A.: Constraining the mass of meteoroids entering the atmosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1027, https://doi.org/10.5194/egusphere-egu24-1027, 2024.