We investigate the dynamical histories of the x-Cygnid and the August Draconid meteoroid streams using numerical N-body simulations. These streams exhibit similar radiants and periods of activity, but possible dynamical connection remains unclear. We map the orbital stability using the MEGNO chaos indicator and perform backward integrations for up to 1000 years, including non-gravitational perturbations. Our results show that the Cygnid-Draconid region contains localized instability islands within the phase space. The August Draconid meteoroids experience a highly chaotic evolution with frequent close encounters with Jupiter, while the x-Cygnids are comparatively less perturbed and concentrate near the 3:2 mean motion resonance with Jupiter. Hypothetical cometary activity simulations reveal that the August Draconids may be observable roughly 88 years after ejection, whereas the x-Cygnids require roughly 174 years. The August Draconids also show a shift in their shower activity to later months. Overall, our results indicate that the x-Cygnids and the August Draconids are unlikely to be dynamically related on the time scales studied.

Meteoroid impacts on the Moon, observed from Earth as flashes typically lasting a few tens of milliseconds, have been monitored for three decades for determining meteoroids' size and mass frequency distribution in the cm to dm range. Studies link these observed impact events to fresh craters advancing our understanding of energy partitioning during an impact. Currently we are transitioning to a new era where lunar impact flashes (LIFs) can be used to supplement upcoming lunar seismology to study the internal lunar structure. Here we present results from the first station of a telescope network under development for continuous LIF monitoring. Observations were carried out during the Geminids 2025 campaign, initiated by the LUMIO Science Team in the framework of their public engagement activities. We detected 53 potential impact flashes and confirmed 11 of them through multiframe observations, and independent detections by other observers. We present evidence suggesting that some of the yet unconfirmed events may be real. Our confirmed events range between magnitude +7.5 and +10.4, primarily in the V and R band. We obtained a high rate of observations per hour, highlighting the importance of high ZHR meteoroid streams for observing LIFs. We also discuss the scientific value of potential LIFs that remain unconfirmed in optical data alone. Even without multi station confirmation, these events can correlate to seismic signals in future lunar seismic networks, thereby providing useful physical constraints on impact processes. This approach would also allow stations equipped with a single telescope/camera to meaningfully contribute to the network.

In meteor science, the identification of meteor showers is a crucial and complex problem. The most common method is to perform a systematic search of a database of observed orbits using an orbit dissimilarity criterion (D-criterion) and an algorithm. D-criteria compare the result of an orbit dissimilarity function (D-function) and a threshold. These D-functions associate one value to two orbits. If this value is lower than the threshold, the orbits are considered similar. In this paper, we focus on the application of these D-criteria on meteoroid orbits. Group of meteors are thus formed using this method. However, not all D-criteria have been evaluated, and their high number makes it hard to know which should be prioritised. This paper presents a review of each D-function, the tests they passed, the threshold choice, and the algorithms they are used with. The aim is both to clearly present the state of the art on this question but also to analyse what studies are missing on this topic. We show what methods are currently used in the search for meteor showers, presenting statistics based on papers justifying the existence of established meteor showers. This paper presents a review of each D-functions from eight different papers. We describe how thresholds are usually chosen and what clustering algorithms can be used with D-criteria to form meteor groups. We also analyse tests that were performed on D-criteria, showing which results they were able to achieve and where they fell short. We discover that most of these criteria were not properly tested, and that some have been criticised for their theoretical background. Thus, we recommend performing a post-search analysis of the groups found, both in a statistical sense (to make sure the groups formed could not have been formed randomly) and an orbital dynamics sense (to check whether the group could indeed come from a singular parent body), to present the findings as potential meteor showers.

Instrumentally determined pre-atmospheric orbits of meteorites offer crucial constraints on the provenance of extraterrestrial material and the dynamical pathways that deliver it to Earth. However, recovery efforts are focused on larger and slower impacts due to their higher survival probabilities and ease of detection. In this study, we investigate the prevalence of these biases in the population of recovered meteorites with known orbits. We compiled a data set of 75 meteorites with triangulated trajectories and compared their orbits to 538 potential 1 g meteorite-dropping fireballs detected by the Global Fireball Observatory, the European Fireball Network, and the Fireball Recovery and InterPlanetary Observation Network. Our results reveal that objects with small semi-major axis values (a1.8 au) appear 2-3 more often than expected. The current sample of meteorites with known orbits does not reflect the sources of meteorites in our collections, and it is essential to account for search and recovery biases to obtain a more representative understanding of meteorite source contributions.

Context. Orbital similarity measures, such as the D-values, have been extensively used in meteor science to identify meteoroid streams and associate meteorite falls with near-Earth objects (NEOs). However, the chaotic nature of near-Earth space challenges the long-term reliability of these measures for stream identification, and the increasing size of our fireball, meteorite fall, and NEO databases make random associations more common. Despite this, many researchers erroneously continue to use orbital similarity beyond its inherent limits. Aims. We aim to assess the statistical significance of using orbital similarity measures for identifying streams of meteoroids or asteroids and explore the implications of chaotic dynamics on the long-term coherence of these streams. Conclusions. The rapid decoherence of meteoroid streams and the chaotic dynamics of near-Earth orbits suggest that no reported stream or NEO associations of meteorites or fireballs are statistically significant according to orbital discriminates. Many are likely coincidental rather than indicative of a true physical link. However, several statistically significant clusters found within the NEO population are consistent with a tidal disruption formation. This contrast and lack of statistically significant associations amongst the impact datasets is likely due to the fireball databases being 2 orders of magnitude smaller than the NEO database and the higher intrinsic uncertainties of fireball observation derived orbits.

Mitigation of the threat from airbursting asteroids requires an understanding of the potential risk they pose for the ground. How asteroids release their kinetic energy in the atmosphere is not well understood due to the rarity of large impacts. Here we present a comprehensive, space-to-laboratory characterization of an impact of an L chondrite, which represents a common type of Earth-impacting asteroid. Small asteroid 2023 CX1 was detected in space and predicted to impact over Normandy, France, on 13 February 2023. Observations from several independent sensors and reduction techniques revealed an unusual but potentially high-risk fragmentation behaviour. The nearly spherical 650 +/- 160 kg (72 +/- 6 cm diameter) asteroid catastrophically fragmented at a dynamic pressure of 4 MPa around 28 km altitude, releasing 98% of its total energy in a concentrated region of the atmosphere. The resulting shock wave was spherical, not cylindrical, and released more energy closer to the ground. This type of fragmentation increases the risk of substantial damage at ground level. These results warrant consideration for a planetary defence strategy for cases where a >3-4 MPa dynamic pressure is expected, including planning for evacuation of areas beneath anticipated disruption locations.

To date only very few meteor clusters have been instrumentally recorded. This means that every new detection is an important contribution to the understanding of these phenomena, which are thought to be evidence of the meteoroid fragmentation in the Solar System. On 31 May 2022, at 6:48:55 UT, a cluster consisting of 52 meteors was detected within 8.5 seconds during a predicted outburst of the tau-Herculid meteor shower. The aim of this paper is to reconstruct the atmospheric trajectories of the meteors and use the collected information to deduce the origin of the cluster. The meteors were recorded by two video cameras during an airborne campaign. Due to only the single station observation, their trajectories were estimated under the assumption that they belonged to the meteor shower. The mutual positions of the fragments, together with their photometric masses, was used to model the processes leading to the formation of the cluster. The physical properties of the cluster meteors are very similar to the properties of the tau-Herculids. This finding confirms the assumption of the shower membership used for the computation of atmospheric trajectories. This was the third cluster that we have studied in detail, but the first one where we do not see the mass separation of the particles. The cluster is probably less than 2.5 days old, which is too short for such a complete mass separation. Such an age would imply disintegration due to thermal stress. However, we cannot rule out an age of only a few hours, which would allow for other fragmentation mechanisms.

This paper reports the approach to determine the luminous efficiency of spacecraft materials experimentally. The idea is that knowing the luminous efficiency of spacecraft materials allows for deriving mass estimates from observation data linking meteor science methods to man-made artificial meteors. This way, observation data from airborne missions and known ground-based meteor observation networks become a versatile tool to analyze destructive spacecraft entry. Material samples were scaled to a typical re-entry condition. The authors recently developed a method to determine the radiant flux in the passbands U, B, and V and the corresponding color indices. The measured mass loss during the experiment is used to determine the luminous efficiency s for the different passbands. These values are reported for three different materials under flow conditions corresponding to two trajectory points at altitudes of 70 km and 65 km in atypical decaying re-entry orbit. The resulting luminous efficiency values are of the order 10 5 , which is about two orders of magnitude lower than meteoroid efficiencies. The found data is applied to fragments observed during the CYGNUS OA-6 observation campaign. The mass loss was extrapolated for the entire duration of the re-entry resulting in amass of around 68-80% of literature values for the mass at the entry interface. (c) 2024 COSPAR. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

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.

Models predict that more than half of all impacting meteoroids should be carbonaceous, reflecting the abundance of carbon-rich asteroids in the main belt and near-Earth space. Yet carbonaceous chondrites represent only about 4 of meteorites recovered worldwide. Here we analyse 7,982 meteoroid impacts and 540 potential meteorite falls from 19 global observation networks and demonstrate that intense thermal stress at low perihelion distances coupled with the filtering effect of Earth`s atmosphere explains this mismatch. Meteoroids repeatedly subjected to intense thermal cycling near the Sun fracture and weaken, removing the most friable objects even before atmospheric entry. Our data also show that tidally disrupted meteoroid streams produce especially fragile fragments that rarely survive to the ground. Consequently, compact, higher-strength, thermally cycled bodies dominate the meteorite record. These findings reconcile the predicted carbonaceous flux with its scarcity in collections, underscoring how orbital evolution and atmospheric filtering shape the materials that reach Earth`s surface.

A new meteor shower $\lambda$-Sculptorids produced by the comet 46P/Wirtanen was forecast for December 12, 2023. The predicted activity was highly uncertain, but generally considered to be low. Observations in Australia, New Zealand, and Oceania were solicited to help constrain the size distribution of meteoroids in the shower. This work aims to characterize the new meteor shower, by comparing the observed and predicted radiants and orbits, and to provide a calibration for future predictions. Global Meteor Network video cameras were used to observe the meteor shower. Multi-station observations were used to compute trajectories and orbits, while single-station observations were used to measure the flux profile. A total of 23 $\lambda$-Sculptorid orbits have been measured. The shower peaked at a zenithal hourly rate (ZHR) of $0.65^{+0.24}_{-0.20}$ meteors per hour at $\lambda_{\odot} = 259.988^{\circ} \pm 0.042^{\circ}$. Due to the low in-atmosphere speed of 15~km s$^{-1}$, the mean mass of observed meteoroids was 0.5~g ($\sim10$~mm diameter), an order of magnitude higher than predicted. The dynamical simulations of the meteoroid stream can only produce such large meteoroids arriving at Earth in 2023 with correct radiants when a very low meteoroid density of $\sim 100$~kg~m$^{-3}$ is assumed. However, this assumption cannot reproduce the activity profile. It may be reproduced by considering higher density meteoroids in a larger ecliptic plane-crossing time window ($\Delta T$ = 20 days) and trails ejected prior to 1908, but then the observed radiant structure is not reproduced.

While comets eject mass mostly at cm-sizes and larger, that size range of particles is mostly absent from the interplanetary medium. Such particles are thought to be lost from the solar system by grain-grain collisions. Here, we investigate the lifetime of cm-sized meteoroids from their abundance in meteoroid streams of different age. For 487 streams, we measured the orbital element dispersions, the magnitude size distribution index, the ratio of fluffy and dense materials in the stream and their bulk densities, and the meteor light curve shape -parameter. We find that older long-period comet meteoroid streams tend to be more dispersed and evolve towards smaller semi-major axis, higher magnitude size distribution index, and contain relatively more high-density material. Meteoroids that approach the Sun closer than 0.2-0.3 AU are mostly young and composed of denser materials poor in sodium. We compare the observed properties of the streams to age estimates from the literature and to a set of new age estimates for long-period comet streams based on observed dispersions. We find that streams broaden with age inversely proportional to the perihelion distance (q). By selecting narrow ranges of age, we find that their magnitude distribution index changes proportional to 1/root q, less steep than expected from meteoroid destruction by collisions. Instead, this shallow dependence suggests a lifetime inversely proportional to the peak grain temperature along its orbit, with the lifetime limited by thermal stresses if 0.3 < q < 1.02 AU and by sublimation if q < 0.2 AU.

The InSight lander (Banerdt et al. 2020) on Mars is equipped with two cameras capable of sky imaging both of which have been used opportunistically to search for meteors. The rate of occurrence of Martian meteors has not been directly measured and initial reports of an imaged meteor by Selsis et al. 2005 were likely incorrect (Domokos et al. 2007). The meteor search is part of the investigation into the flux of impactors at Mars (Daubar et al. 2018). The InSight cameras have been described by Maki et al. (2018). The Instrument Deployment Camera (IDC) can be aimed by a robotic arm and has a 45-degree square field of view (FOV). However, this camera was typically unavailable, and has only been used twice. The Instrument Context Camera (ICC) has a 120-degree fisheye FOV. It is aimed downward, but sees a broad section of the southern sky to around 20-degrees elevation angle. IDC images are shown in Fig. 1. They were aimed to the southwest at an elevation of about 35 degrees, and on sols 126 and 176 (5 April and 27 May 2019), four 5-minute exposures were acquired. Stars are visible in the images, and will be used to determine the sensitivity. Many cosmic rays were seen (e.g., Fig. 2)—long ones can be mistaken for meteors, but they have a distinctive morphology with a narrow end and a diffuse end due to the charge diffusion process after the charged particles pass through the detector (Fisher-Levine and Nomerotski, 2015). Despite the Sun being 60 degrees down, diffuse sky brightness was visible (Banfield et al. 2020). No meteors were detected. ICC images are shown in Fig. 3—about 75% of the images do not include sky. On 25 sols from 254 to 432 (15 August 2019 to 6 February 2020), the ICC acquired four, 5-minute exposures. No meteors were seen. We will present an analysis of the results and their implication for the meteor rate at Mars. While no meteors were seen, the upper limit is likely to be constraining. Total exposure time is 540 minutes, using cameras more sensitive than the limiting exposures of Domokos et al. (2007) and with wider FOVs. However, the complex geometry and the time variable atmospheric dust extinction will be considered. References. Banerdt et al. 2020. Nature Geoscience, 13, 183-189. Banfield et al. 2020. Nature Geoscience, 13, 190-198. Daubar et al. 2018. Space Science Rev. 214, 132. Domokos et al. 2007. Icarus 191, 141-150. Fisher-Levine and Nomerotski 2015. BNL-108381-2015-JA. Maki et al. 2018. Space Sci. Rev. 214, 105. Selsis et al. 2005. Nature 435, 581.

Context. Jupiter-family comets (JFCs), which originate from the Kuiper belt and scattered disk, exhibit low-inclination and chaotic trajectories due to close encounters with Jupiter. Despite their typically short incursions into the inner solar system, a notable number of them are on Earth-crossing orbits, with fireball networks detecting many objects on "JFC-like" (2 < T-J < 3) orbits. Aims. This investigation aims to examine the orbital dynamics of JFCs and comet-like fireballs over 10(4) yr timescales, focusing on the trajectories and stability of these objects in the context of gravitational interactions within the solar system. Methods. We employed an extensive fireball dataset from Desert Fireball Network (DFN), European Fireball Network (EFN), Fireball Recovery and InterPlanetary Observation Network (FRIPON), and Meteorite Observation and Recovery Project (MORP), alongside telescopically observed cometary ephemeris from the NASA HORIZONS database. The study integrates 646 fireball orbits with 661 JFC orbits for a comparative analysis of their orbital stability and evolution. Results. The analysis confirms frequent Jupiter encounters among most JFCs, inducing chaotic orbital behavior with limited predictability and short Lyapunov lifetimes (similar to 120 yr), underscoring Jupiter's significant dynamical influence. In contrast, "JFC-like" meteoroids detected by fireball networks largely exhibit dynamics divergent from genuine JFCs, with 79-92% on "JFC-like" orbits shown not to be prone to frequent Jupiter encounters; in particular, only 1-5% of all fireballs detected by the four networks exhibit dynamics similar to that of actual JFCs. In addition, 22% (16 of 72) of near-Earth JFCs are on highly stable orbits, suggesting a potential main belt origin for some of the bodies. Conclusions. This extensive study delineates the stark dynamical contrast between JFCs and JFC-like meteoroids detected by global fireball networks. The majority of centimeter- and meter-scale meteoroids on JFC-like orbits exhibit remarkably stable trajectories, which starkly differ from the chaotic paths of their km-scale counterparts. Our findings suggest that the JFC-like objects observed by fireball networks predominantly originate from the outer main belt, with only a minor fraction being directly attributable to traditional JFCs.

We provide an overview of the MetSpec project, which aims to connect meteorite ablation laboratory experiments with meteor spectral observations in the atmosphere aiming at the development of a methodology to identify incoming planetary material distribution into the Earth’s atmosphere. We have selected 28 meteorites of different types to represent known planetary material compositions coming from asteroids, Vesta, Mars and the Moon. Some samples have been tested twice which resulted in overall 31 experiments. Three distinct test campaigns were realized in 2020, 2021 and 2022 with the High Enthalpy Flow Diagnostics Group in the Plasma Wind Tunnel PWK1 where they have developed a unique testing scenario. During the last and most elaborated campaign, 16 cameras observed the artificial meteors in the laboratory. Besides videos and online live streaming, instruments included several spectrometers, and optical and imaging instruments covering UV, visible and IR spectral range. This special collection in Icarus collects the resulting output from the different instruments and results. This overview article provides an introduction and summarizes the main findings of the experimental campaigns.

Lunar impact flashes: first detection from the Observatory of NiceAvdellidou(1),M. Delbo(1), E. Munaibari(1), R. Larson(2), J. Vaubaillon(3), P. Hayne(2), D. Sheward(3), A. Cook(3)(1)Laboratoire Lagrange, Observatoire de la Côte d’Azur, UCA, France (2)University of Colorado, USA (3)IMCCE, Observatoire de Paris, France (4)Aberystwyth University, UK contact: chrysa.avdellidou@oca.euAbstractWe report the first lunar flash due to meteoroid impact observed by our team at Observatoire de la Côte d’Azur (OCA) in south France.IntroductionMeteoroids impacting onto the lunar surface can produce very short bursts of light–commonly calledimpact flashes. Such flashes have been the subject of several lunar monitoring surveys over the last 20 years (1,2,3) for the purpose of determining the size frequency distribution of near-Earth objects in the cm–dm size range. The goal of our international team is to build a network of moderate telescopes that will survey the lunar surface for impact flashes and subsequently locate the produced impact craters. We have developed all the necessary algorithms in order to detect the flash events in real time during the observations, identify the selenographic coordinates, link the meteoroid to a parent meteoroid stream, measure the mass and size of the meteoroid (4) and discover the potential fresh lunar crater. Updates on the methodology is presented by the accompanying EPSC 2020 abstract of Munaibari & Larson et al. The description of the crater identification is presented by the accompanying EPSC 2020 abstract of Sheward et al.First confirmed impact flash from OCAOn the night of May 27th, 2020 at 20:48:49.420 UTC, we detected our first impact flash from the Observatoire de la Côte d’Azur (site of Mt. Gros). This is the first live impact observed for the project "Flash!", the first from the Observatoire de la Côte d’Azur and the first from all France by professional sites. The telescope used is a 16" MEADE coupled with a CMOS ASI ZWO 183mono camera. The frame rate was 20 fps and the frame integration time was 0.05 sec. The telescope was guiding on the lunar crescent using the lunar autoguider that we developed in the framework of the master course of MAUCA (University of Côte d’Azur). AcknowledgementsThis work was supported by the ProgrammeNational de Planetologie (PNP), France ofCNRS/INSU, co-funded by CNES, France and bythe program "Flash!" supported by Crédits Scientifiques Incitatifs (CSI), France of the UniversitéNice Sophia Antipolis. This work has made use ofdata from the European Space Agency (ESA) NELIOTA project. We thank the EUR Spectrum for supporting Mr. Munaibari with a 3-monthUCA Master Scholarship to perform this masterthesis. References[1] J. L. Ortiz, et al.A&A,343: L57–L60, (1999).[2] J. L. Ortiz, et al. Nature, 405:921–923, (2000).[3] R. M. Suggs, et al.Icarus,238:23–36, (2014).[4] C. Avdellidou & J. Vaubaillon.MNRAS, 484(4):5212–5222, (2019).

Emission spectra and diagnostic spectral features of a diverse range of ablated meteorite samples with a known composition are presented. We aim to provide a reference spectral dataset to improve our abilities to classify meteoroid composition types from meteor spectra observations. The data were obtained by ablating meteorite samples in high-enthalpy plasma wind tunnel facilities recreating conditions characteristic of low-speed meteors. Near-UV to visible-range (320-800 nm) emission spectra of 22 diverse meteorites captured by a high-resolution Echelle spectrometer were analyzed to identify the characteristic spectral features of individual meteorite groups. The same dataset captured by a lower-resolution meteor spectrograph was applied to compare the meteorite data with meteor spectra observations. Spectral modeling revealed that the emitting meteorite plasma was characterized by temperatures of 3700-4800 K, similar to the main temperature component of meteors. The studied line intensity variations were found to trace the differences in the original meteorite composition and thus can be used to constrain the individual meteorite classes. We demonstrate that meteorite composition types, including ordinary chondrites, carbonaceous chondrites, various achondrites, stony-iron and iron meteorites, can be spectrally distinguished by measuring relative line intensities of Mg I, Fe I, Na I, Cr I, Mn I, Si I, H I, CN, Ni I, and Li I. Additionally, we confirm the effect of the incomplete evaporation of refractory elements Al, Ti, and Ca, and the presence of minor species Co I, Cu I, and V I.

Lunar impact flashes: analysis methodsMunaibari(1), R. Larson(2), C. Avdellidou(1), M. Delbo(1), J. Vaubaillon(3), P. Hayne(2), D. Sheward(4), A. Cook(4)(1)Laboratoire Lagrange, Observatoire de la Côte d’Azur, UCA, France(2)University of Colorado, USA(3)IMCCE, Observatoire de Paris, France(4)Aberystwyth University, UKcontact: chrysa.avdellidou@oca.euAbstractWe present our complete method to analyse lunar impact flashes; from the identification of the selenographic coordinates to the estimation of masses and sizes of the meteoroids. For this work we used archival data from the ESA-funded NELIOTA survey and we report an updated catalogue of the impact coordinates and link to meteoroid streams. This project is in the framework of our project Flash!, which aims to detect impacts in real time during the observations, identify the lunar coordinates and attempt the discovery of the fresh craters using LRO data. The scientific problem is to establish a link between the diameter of the meteoroid impactor and the diameter of the impact crater quantifying this scaling with live impact observations.Selenographic coordinates and link to meteor streamsIn this work, we exploit the publicly available datafrom NELIOTA (1,2), an ESA-funded survey at the National Observatory ofAthens (NOA). The first step is to identify the impact coordinates on the Moon. Using the method described by Larson et al. EPSC 2019 we have discovered that several impact locations given by the NELIOTA team are inaccurate and in some cases are off by 10s of degrees.The importance ofaccurately locating the position of an impact flashcomes for the fact that it is needed to perform theprocess of linking the impactor to its source and this is crucial to identify the originof the impactor. In this work we evolve from our previous studies (3) and we investigate also the possibility an impactor to originate from the sporadic population and not only from meteoroid streams. Masses and Sizes of the meteoroidsAccording to previous studies (2,3), an impact flashis treated as a black body whose spectral energy distribution is described by Planck’s law. Using the flash magnitudes in R and I bands we estimate temperature values as described with details in (3). The mass of an impactor can be derived from its kinetic energy (KE). To calculate the impact KE it is necessary to measure the luminous energy ELum from the telescopic observations, which is just asmall fraction, η, of the KE.In order to be able to estimate the kinetic energyof an impactor, it is essential to know the velocityat which it impacted onto the lunar surface. Thisvelocity is obtained by linking the impactor to its source, either a known meteoroid stream or the sporadic background population. In the case of streams, the velocity of their meteoroids is known.Once the link is established, the velocity of an impactor is easily computed by finding the differencebetween the velocity of the meteor shower’s particles and that of the Moon at the time of the impact.Assuming a spherical shape for the impactors andwith the estimation of their masses we can now estimate their sizes. In this work, we utilised th e bulk densities that have been reported (4) for the fragments of some ofthe shower streams by assigning impactors with thebulk density of the meteor showers we found to betheir plausible sources. Finally, we construct the size frequency distribution with a slope of -2.48 as shown in Fig.1 and is comparable with the NASA survey (5). AcknowledgementsThis work was supported by the ProgrammeNational de Planetologie (PNP), France of CNRS/INSU, co-funded by CNES, France and bythe program "Flash!" supported by Crédits Scientifiques Incitatifs (CSI), France of the UniversitéNice Sophia Antipolis. This work has made use ofdata from the European Space Agency (ESA) NELIOTA project. We thank the EUR Spectrum for supporting Mr. Munaibari with a 3-month UCA Master Scholarship to perform this masterthesis.References[1] E. Xirouris, et al. A&A,619, A141 (2018).[2] A. Z. Bonanos, et al. A&A, 612 (2018)[3] C. Avdellidou & J. Vaubaillon. MNRAS, 484(4):5212–5222 (2019).[4] P. B. Babadzhanov & G. I. Kokhirova., A&A, 495:353–358(2009).[5] R. Suggs et al. Icarus, 238, 23 (2014).

Context. Dynamically linking a meteor shower with its parent body is challenging, and chaos in the dynamics of meteoroid streams may contribute to this challenge. For a robust identification of parent bodies, it is therefore necessary to quantify the amount of chaos involved in the evolution of meteoroid streams. Aims. Characterising chaos in meteoroid streams through the aid of chaos maps is still a new field of study. Thus, we examine two very different meteoroid streams, the Draconids and the Leonids, in order to obtain a general view of this topic. Methods. We used the method developed in a previous paper dedicated to Geminids, drawing chaos maps with the orthogonal fast Lyapunov indicator. We chose four particle size ranges to investigate the effect of non-gravitational forces. As the dynamics are structured by mean-motion resonances with planets, we computed the locations and widths of the resonances at play. We used semi-analytical formulas valid for any eccentricity and inclination and an arbitrary number of planets. Results. We pinpoint which mean-motion resonances with Jupiter play a major role in the dynamics of each meteoroid stream. We show how those resonances tend to trap mostly large particles, preventing them from meeting with Jupiter. We also study particles that manage to escape those resonances, for example, due to the gravitational perturbation of Saturn. Finally, we explain why non-gravitational forces do not disturb the dynamics much, contrary to what is observed for the Geminids.

A set of 28 different meteorites was tested in 32 ablation experiments in the plasma wind tunnel PWK1 at the Institute of Space Systems. All meteorites were exposed to the same flow condition in consecutive experiments. This paper presents the detailed analysis of high-resolution images taken by DSLR cameras during 26 experiments on 22 different meteorites. It is seen that the ablation behavior of the meteorites differs in the way the material melts and flows downstream. While some meteorites appeared more viscous and most material remained connected to the main body, other samples suggest a much lower viscosity as the material was carried downstream and released droplets to the flow. Most droplets of molten material were seen for the two most carbon rich samples from meteorites Murchison and Dhofar 1575. The release of blue colored particles was observed for several meteorites, independent of the viscosity. In contrast to the molten droplets, the blue particles also traveled up to a few millimeters upstream. The abundance of these blue particles is linked to the iron content. Close to no particles or droplets were observed for achondritic samples.