Meteoroid structure and bulk density are key indicators of its origin and thermal processing history. Physical properties of meteoroids with known parent bodies are of special interest and they provide an indirect way to probe the parent body itself (Flynn, 2004; Koten et al., 2019). The bulk density of shower meteoroids is a necessary assumption in dynamical simulations of meteoroid streams (Vaubaillon et al., 2005; Egal et al., 2019), with a major impact on the predicted particle sizes arriving on Earth (Vida et al., 2024) and the accuracy of meteor shower outburst predictions (Ye et al., 2014). The bulk density is also a key variable in spacecraft risk assessment, where the depth of hypervelocity impact craters scales with d ∝ ρ^4/27 (Moorhead et al, 2017).

This work discusses the latest meteoroid ablation and fragmentation modelling efforts using the Canadian Automated Meteor Observatory (CAMO) mirror tracking system (Vida et al., 2021). The instrument tracks meteors in real-time and provides 100 frame-per-second video at meter-scale spatial measurement accuracy. Meteors can be tracked to a limiting magnitude of +8. This high spatial resolution and sensitivity allow observing details of fragmentation and the wake profile.

A meteoroid ablation model which assumes meteoroids fragment gradually, by releasing micrometer-sized refractory grains from their surface (Borovička et al., 2007), was applied to observations of several major meteor showers. The model fits were performed manually using a trial-and-error method. The model is constrained by the observed light curve, dynamics (velocity and deceleration), and wake; the latter strongly informing the production rate and size distribution of released grains (Vida et al., 2024).

The method has so far been applied to 14 meteor showers (Egal et al., 2023; Buccongello et al., 2024; Pinhas et al., 2024) which cover a range of bulk densities from 250 to 1400 kg/m³: tau-Herculids, Orionids, July Pegasids, eta-Aquariids, Perseids, Leonids, Aurigids, Lyrids, Taurids, December Monocerotids, alpha-Capricornids, eta-Lyrids, Geminids, and Southern delta-Aquariids. The most surprising finding was that meteoroids from several showers have a two-part structure: a dense non-eroding core embedded in a softer matrix. This structure appears on both ends of the density range, in low-density (300 kg/m³) Orionids and in Southern delta-Aquariids which have bulk densities akin to carbonaceous chondrites (~1400 kg/m³).

In general, these new estimates are at variance with previous estimates by Kikwaya et al. (2011) who found that meteoroids of Jupiter-family comet (JFC) origin have chondritic densities (~3500 kg/m³). In contrast, new estimates for mean bulk densities of ~600 kg/m³ were found for JFC shower meteoroids and ~350 kg/m³ for Halley-type meteoroids, consistent with in-situ measurements.

Finally, an overview of the latest efforts to automate model fits and provide realistic parameter uncertainties is given.

References

Borovička, J., Spurný, P., & Koten, P. (2007). Atmospheric deceleration and light curves of Draconid meteors and implications for the structure of cometary dust. Astronomy & Astrophysics, 473(2), 661-672.

Buccongello, N., Brown, P. G., Vida, D., & Pinhas, A. (2024). A physical survey of meteoroid streams: Comparing cometary reservoirs. Icarus, 410, 115907.

Egal, A., Wiegert, P., Brown, P. G., Moser, D. E., Campbell-Brown, M., Moorhead, A., ... & Moticska, N. (2019). Meteor shower modeling: Past and future Draconid outbursts. Icarus, 330, 123-141.

Egal, A., Wiegert, P. A., Brown, P. G., & Vida, D. (2023). Modeling the 2022 τ-herculid outburst. The Astrophysical Journal, 949(2), 96.

Flynn, G. J. (2004). Physical properties of meteorites and interplanetary dust particles: clues to the properties of the meteors and their parent bodies. Earth, Moon, and Planets, 95, 361-374.

Kikwaya, J. B., Campbell-Brown, M., & Brown, P. G. (2011). Bulk density of small meteoroids. Astronomy & Astrophysics, 530, A113.

Koten, P., Rendtel, J., Shrbený, L., Gural, P., Borovička, J., & Kozak, P. (2019). Meteors and meteor showers as observed by optical techniques. Meteoroids: Sources of Meteors on Earth and beyond, 90.

Moorhead, A. V., Blaauw, R. C., Moser, D. E., Campbell-Brown, M. D., Brown, P. G., & Cooke, W. J. (2017). A two-population sporadic meteoroid bulk density distribution and its implications for environment models. Monthly Notices of the Royal Astronomical Society, 472(4), 3833-3841.

Pinhas, A., Krzeminski, Z., Vida, D., & Brown, P. (2024). Quantifying the bulk density of southern delta aquariid meteoroids: insights from the Canadian automated meteor observatory. Monthly Notices of the Royal Astronomical Society, 529(4), 4585-4601.

Vaubaillon, J., Colas, F., & Jorda, L. (2005). A new method to predict meteor showers-I. Description of the model. Astronomy & Astrophysics, 439(2), 751-760.

Vida, D., Brown, P. G., Campbell-Brown, M., Weryk, R. J., Stober, G., & McCormack, J. P. (2021). High precision meteor observations with the Canadian automated meteor observatory: Data reduction pipeline and application to meteoroid mechanical strength measurements. Icarus, 354, 114097.

Vida, D., Brown, P. G., Campbell-Brown, M., & Egal, A. (2024). First holistic modelling of meteoroid ablation and fragmentation: A case study of the Orionids recorded by the Canadian Automated Meteor Observatory. Icarus, 408, 115842.

Vida, D., Scott, J. M., Egal, A., Vaubaillon, J., Ye, Q. Z., Rollinson, D., ... & Moser, D. E. (2024). Observations of the new meteor shower from comet 46P/Wirtanen. Astronomy & Astrophysics, 682, L20.

Ye, Q., Wiegert, P. A., Brown, P. G., Campbell-Brown, M. D., & Weryk, R. J. (2014). The unexpected 2012 Draconid meteor storm. Monthly Notices of the Royal Astronomical Society, 437(4), 3812-3823.

How to cite: Vida, D.: Meteoroid bulk densities – a meteor shower survey, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-146, https://doi.org/10.5194/epsc2024-146, 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.

How to cite: Courtot, A., Vaubaillon, J., and Fouchard, M.: Chaos maps as tools to explore meteoroid streams dynamics, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-95, https://doi.org/10.5194/epsc2024-95, 2024.

Meteor showers, originating from disruptions of comets or asteroids, offer insights into the composition and dynamics of the Solar System. However, distinguishing sporadic meteors from those belonging to specific meteoroid streams remains a challenge.

This study evaluates four orbital similarity criteria within a five-dimensional parameter space (D_SH, D_D, D_H, and ϱ₂ [1-4]) for dynamical associations, using the CAMS database as a benchmark. Additionally, we assess various Machine Learning distance metrics with two vectors: ORBIT (based on heliocentric orbital elements) and GEO (based on geocentric observational parameters). We test the Top-k agreement and compute the optimal cut-offs for distinguishing sporadic events by analyzing the ROC curve using Youden’s J statistic [5].

Our findings indicate that the sEuclidean metric paired with the GEO vector demonstrates superior performance compared to other metrics and the D-criteria, achieving the highest Top-1 accuracy of 87.06%. Among the D-criteria, D_SH is the most effective for Top-1 accuracy at 86.23%, while ϱ₂ leads in both Top-5 (95.67%) and Top-10 (97.93%) accuracy. The Bray-Curtis metric, when combined with the ORBIT vector, consistently outperforms other distance metrics and the D_D criterion across all Top-k tests, achieving Top-1, Top-5, and Top-10 accuracies of 83.96%, 94.10%, and 96.61%, respectively. D_D exhibits an opposite trend to other D-criteria when evaluated against distance metrics with the GEO vector. In general, ϱ₂ appears to be the most comparable to distance metrics using the GEO vector and is the most compatible with both GEO and ORBIT vectors simultaneously.

The mean accuracies for Top-1, Top-5, and Top-10 tests are 83.7%, 93.6%, and 96.2%, respectively, with the highest accuracies achieved using the GEO vector (85.1%, 93.4%, 95.9%) rather than the ORBIT vector (81.8%, 93.2%, 95.9%). This suggests that geocentric parameters provide a more robust basis than orbital elements for meteor dynamical association.

The sEuclidean metric, when used with the GEO vector, achieves the highest overall accuracy (84.34%) and Matthews correlation coefficient (phi) of 0.6464, closely followed by Cityblock and Bray-Curtis metrics. Among the D-criteria, D_SH distinguishes itself with a phi of 0.6400, translating to an accuracy rate of 84.17% in separating the background, while D_D emerges as the least effective, with a phi of 0.5877 and an accuracy of 81.87%. In the context of the ORBIT vector, Cityblock takes the lead with a phi of 0.6359 and 84.04% accuracy, closely followed by Bray-Curtis and Euclidean metrics.

Excluding the Cosine metric, all distance metrics associated with the GEO vector surpass the D-criteria in phi when differentiating the meteoroid background. Despite the generally lower performance of the ORBIT vector, various distance metrics still exceed certain D-criteria in effectiveness. Optimal cut-offs for all D-criteria and distance metrics are provided, based on the CAMS database classification. See Table 1. The complete details of this work can be found in [6]

Table 1. Threshold, accuracies, and Matthews correlation coefficients for different D-criteria and distance metrics in the CAMS database taking into account the sporadic and associated events.

In conclusion, this study reveals that Machine Learning distance metrics can rival or even outperform specifically tailored orbital similarity criteria for meteor dynamical association.  

References

[1] Southworth, R. B., & Hawkins, G. S. (1963). Smithsonian Contributions to Astrophysics, 7, 261–285.

[2] Drummond, J. D. (1981). Icarus, 45(3), 545–553.

[3] Jopek, T. J. (1993). Icarus, 106(2), 603–607. 

[4] Kholshevnikov, K. V., Kokhirova, G. I., Babadzhanov, P. B. et al. (2016). Monthly Notices of the Royal Astronomical Society, 462(2), 2275–2283.

[5] Youden, W. J. (1950). Cancer, 3(1), 32–35.

[6] Peña-Asensio E., & Sánchez-Lozano J.M. (2024). Advances in Space Research, in press, https://doi.org/10.1016/j.asr.2024.05.005.

How to cite: Peña-Asensio, E. and Sánchez-Lozano, J. M.: Distance metrics for dynamical association of meteors, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-736, https://doi.org/10.5194/epsc2024-736, 2024.

How to cite: Christou, A. and Gritsevich, M.: Characterising the meteoroid environment at 0.7 au from the sun with a Venus-orbiting meteor camera: a feasibility study, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-204, https://doi.org/10.5194/epsc2024-204, 2024.

Abstract: 

It has been argued within the scientific community that meteoroids of all sizes fragment. Observations with the high-resolution optical network CAMO (Canadian Automated Meteor Observatory) have shown obvious fragments for 90% of meteoroids (Subasinghe et al., 2016). The remaining 10% may fragment as well, as Campbell-Brown et al. (2017) showed that even meteors with a very short wake cannot be fitted with a single body model.

Fragmentation is essential for a proper characterization of the structure and composition of meteoroids. In turn, the latter determine the dynamics of meteoroids in space, their ablation behavior when they enter the atmosphere and the potential damage that they cause to spacecraft. Ignoring fragmentation leads notably to an overestimation of ablation coefficients, an underestimation of meteoroid densities (Moorhead et al, 2017) and limit the accuracy in the determination of meteoroid orbits (Vida et al, 2018).

Direct measurements of fragmentation are particularly important for a better understanding of the underlying phenomenon and for improving the existing ablation models. Although high-resolution observations of meteor trails through optical means at mm-sizes have been done in the recent years (e.g., Campbell-Brown, 2017; Vida et al., 2021), there are few works performing fragmentation characterization through radio observations.

An approach that utilizes both the phase and amplitude associated to the radio echo of a meteor was developed by Elford (2001). This technique, called Fresnel Transform (FT), allows to study the structure of the ionized trail immediately behind the head of the meteor. Although it is highly effective for computing the variation of the electron line density along the trail and therefore characterizing fragmentation, to date the FT has been mainly used for the computation of meteoroid velocity (Baggaley & Grant, 2005; Campbell & Elford, 2006; Holdsworth et al., 2007; Roy et al., 2007).

We will present progress of a new Python software package which allows the computation of the FT applied to meteor echoes, with a specific aim of statistically examining the process of fragmentation at small meteoroid sizes.

With this software, we will apply the FT to meteor echoes detected by the Canadian Meteor Orbit Radar (CMOR) and compare the results with the high-resolution imagery furnished by CAMO as validation. This comparative analysis will validate both the accuracy of the Python tool and the physical interpretation of the scattering amplitudes produced by the FT.

This tool will be applicable in an automated mode to both backscatter and forward-scatter data, providing a versatile framework for meteoroid analysis. This project will, for the first time, enable us to examine fragmentation of small meteoroids in a self-contained manner.

References:        

- Subasinghe D., Campbell-Brown M. D., Stokan E. (2016). Physical characteristics of faint meteors by light curve and high-resolution observations, and the implications for parent bodies. Monthly Notices of the Royal Astronomical Society, 457(2), 1289–1298. https://doi.org/10.1093/mnras/stw019

- Campbell-Brown M. D. (2017). Modelling a short-wake meteor as a single or fragmenting body. Planetary and Space Science, 143, 34-39. https://doi.org/10.1016/j.pss.2017.02.012

- Moorhead A. V., Blaauw R. C., Moser D. E, Campbell-Brown M. D., Brown. P.G., Cooke W. J. (2017). A two-population sporadic meteoroid bulk density distribution and its implications for environment models. Monthly Notices of the Royal Astronomical Society, 472(4), 3833-3841. https://doi.org/10.1093/mnras/stx2175

- Vida D., Brown P. G., Campbell-Brown M. D. (2018). Modelling the measurement accuracy of pre-atmosphere velocities of meteoroids. Monthly Notices of the Royal Astronomical Society, 479(4), 4307–4319. https://doi.org/10.1093/mnras/sty1841

- Vida D., Brown P. G., Campbell-Brown M. D, Weryk R. J., Stober G., McCormack J. P. (2021). High precision meteor observations with the Canadian automated meteor observatory: Data reduction pipeline and application to meteoroid mechanical strength measurements. Icarus, 354, 114097. https://doi.org/10.1016/j.icarus.2020.114097.

- Elford W. G. (2001). Observations of the structure of meteor trails at radio wavelengths using Fresnel holography. ESASP, 495, 405–411. https://ui.adsabs.harvard.edu/abs/2001ESASP.495..405E/abstract

- Baggaley W. J., Grant J. (2005). Techniques for Measuring Radar Meteor Speeds. In: Hawkes, R., Mann, I., Brown, P. (eds). Modern meteor science: an interdisciplinary view. Springer, Dordrecht. https://doi.org/10.1007/1-4020-5075-5_56

- Campbell L. A., Elford W. G. (2006). Accuracy of meteoroid speeds determined using a Fresnel transform procedure. Planetary and Space Science, 54(3), 317–323. https://doi.org/10.1016/j.pss.2005.12.016

- Holdsworth D. A., Elford W. G., Vincent R. A., Reid I. M., Murphy D. J., Singer W. (2007). All-sky interferometric meteor radar meteoroid speed estimation using the Fresnel transform. Annales Geophysicae, 25(2), 385–398. https://doi.org/10.5194/angeo-25-385-2007

- Roy A., Doherty J. F., Mathews J. D. (2007). Analyzing radar meteor trail echoes using the Fresnel transform technique: a signal processing viewpoint. Earth Moon Planet, 101, 27–39. https://doi.org/10.1007/s11038-007-9147-5

How to cite: Balis, J., Brown, P., Lamy, H., and Jehin, E.: Fresnel holography for radio characterization of meteoroid fragmentation, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-626, https://doi.org/10.5194/epsc2024-626, 2024.

How to cite: Gritsevich, M., Kastinen, D., and Kero, J.: Physical Modeling of Meteors based on Radar Data, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-1309, https://doi.org/10.5194/epsc2024-1309, 2024.

Introduction

This presentation will demonstrate the sensitivity of meteoroid orbit determination to errors in meteor measurements. Both parameters, speed and radiant, influence the computed heliocentric velocity of a meteoroid prior to encountering Earth, thus impacting its orbit determination. Whether a meteoroid's orbit is closed or open relative to the Sun determines its nature and origin. Unambiguously identifying an interstellar meteoroid therefore necessitates understanding the validity limits provided by uncertainties in these parameters. However, uncertainties in meteor databases are often underestimated or unknown. We introduce a general tool for estimating the accuracy of determined uncertainties in the data.

Hyperbolic excess velocities

Meteor observations provide direct insights into the original extraterrestrial material that formed our solar system and its distribution in Earth's vicinity and beyond. Detecting an interstellar meteoroid could offer clues about the materials in our nearby solar environment or the building blocks of exoplanetary systems.

However, the sole indicator of a particle's interstellar origin is a hyperbolic meteoroid orbit relative to the Sun, while the expected hyperbolic excess of a meteoroid's heliocentric velocity closely approximates the common uncertainty in velocity determination. Consequently, unambiguously identifying an interstellar meteoroid is exceedingly challenging, requiring a comprehensive examination of potential biases and errors.

The accuracy of the data determines the relevance of the conclusions drawn from the scientific results obtained from observed data, especially in meteor astronomy, where the orbit of an object prior to its encounter with Earth is derived from a phenomenon lasting only a few seconds in the atmosphere. Here, we demonstrate how the measured geocentric parameters, including both the meteor velocity v and the angular elongation ε of its apparent radiant from the Earth's apex, impact the resulting meteoroid orbit.

Kresaks’ diagram

It is possible to display both geocentric quantities (v and ε) of a meteor and observe the heliocentric orbit of the meteoroid on the same plot. As introduced by Lubor Kresak and Margita Kresakova in 1976 [1], such a diagram facilitates sufficiently accurate estimations to distinguish between various types of orbits. Hence, such a display is very useful when analyzing hyperbolic orbits [2]. For each hyperbolic meteor, it is possible to estimate the uncertainties in speed and radiant position, which may have shifted the event beyond the parabolic limit. But it is also useful for verifying whether the uncertainties of the dataset as a whole are not underestimated. If so, the spread of meteors in the data smoothly continues beyond the parabolic limit to much higher values than the uncertainties should have allowed [3].

The recent well-known case of an interstellar meteoroid candidate

A notable example is the fireball detected by U.S. Government sensors on January 8, 2014. Based on its parameters, provided in the CNEOS^A catalog, the meteoroid exhibits a hyperbolic excess velocity, leading to its proposal as a candidate for an interstellar meteoroid [4]. Reports also suggest that fragments of this fireball were found on the ocean floor near Papua New Guinea, further supporting its potential interstellar origin [5]. The case has been re-analyzed in connection with the entire catalog, and it has been concluded that, based on the available data, there is no evidence to support the interstellar origin of any of the nominally hyperbolic fireballs from this data [6].

Acknowledgements. This work was supported by the Slovak Grant Agency for Science, grant No. 2/0009/22.

References

[1] Kresak, L. and Kresakova, M., 1976, BAC, 27, 106

[2] Hajdukova, M., Sterken V.J., and Wiegert, P., 2019, in Meteoro-ids: Sources of Meteors on Earth and Beyond, CUP, 235

[3] Barghini, D., Durisova, S., Koten, P., and Hajdukova, M., 2024, in preparation

[4] Siraj, A. and Loeb, A., 2022, Astrophys. J., 939, 53

[5] Siraj, A., Loeb, A., and Gallaudet, T. 2022, arXiv e-prints, arXiv:2208.00092

[6] Hajdukova, M., Stober, G., Barghini, D., Koten, P., Vaubaillon, J., Sterken, V.J., Durisova, S., Jackson, A., and Desch, S., 2024, in preparation

^Ahttps://cneos.jpl.nasa.gov/fireballs/

How to cite: Hajdukova, M.: Interstellar meteoroids based on meteor observations: persistent controversies, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-838, https://doi.org/10.5194/epsc2024-838, 2024.

FRIPON project

The FRIPON fireball project was initially conceived and founded in France in 2014 with a grant from the ANR (Agence Nationale de la Recherche), the objective was to cover the country with a dense network of all-sky cameras (~ a hundred with 80 km spacing). We built (Colas at al 2020) [1] a centralized network, a data storage architecture and a real-time data processing (astrometry of each camera, triangulation of each event to calculate the trajectory of the bright flight and finally determination of the scientific parameters: orbit, incoming mass, final mass, etc.). A catalog of orbits is produced each year and is available on the fireball.fripon.org website. The FRIPON project is designed as a real-time network, the aim of which is to trigger a search in the field within 24 hours of the fall in order to recover fresh meteorites.

Extension and results

The architecture developed for the network allows for easy expansion, and from 2016, scientists from neighboring countries were interested in joining the project using the same hardware, software and infrastructure. The main extensions involved Italy (PRISMA), Germany (FRIPON-Germany), Romania (MOROI), the United Kingdom (SCAMP), Canada (DOME), the Netherlands (DOERAK), Spain (SPMN), Belgium (FRIPON-Belgium), Switzerland (FRIPON-Switzerland), South America (FRIPON-Andino), Morocco (MOFID) and Senegal (ASAMAAN). FRIPON (www.fripon.org) is now an international project and the French network is now FRIPON-VigieCiel (www.vigie-ciel.org) a merger of the camera network and of the Vigie-Ciel citizen science project supported by Muséum national d'Histoire naturelle with the aim of involving the general public in finding meteorites by learning how to identify them and thus take part in research. Ten years after the start of the network, we now have 250 active cameras, we have obtained more than 10,000 orbits and our data has been used in the recovery of 7 meteorites (Cavezzo 2020, Winchcombe 2020, Kindberg 2021, Saint-Pierre-le-Viger 2023, Matera 2023, Menetréol 2023, Ribbeck 2024). It is important to note that over these 10 years, more than 20 searches have been organized without positive results, as the recovery efficiency is often far from 100% due to vegetation, private land, etc.

Recovery statistics

Roughly 600 detections per year included at least one French camera, as described in (Colas et al 2020) [1] this corresponds to objects larger than 1 cm and is compatible with the surface area of the national territory (10⁶ km²) according to the previous estimate (Brown et al 2002) [2]. As it also predicts the fall of around 10 meteorites per year for France, we hoped at the start of the project to recover about one meteorite per year, which seems realistic: 50% of meteorites fall during the day, cloud cover is around 50% and ground searches are difficult one time out of two. Another clue is that in the 19th century, one meteorite was recovered every two years in France (Colas, 2020) [1]. Unfortunately, after 10 years of operation, we have only recovered 2 meteorites in France, which is a little disappointing but still better than the 20th century efficiency of one meteorite every 10 years. In the end, the realistic recovery rate seems close to one meteorite per year, but for all of Europe! Since the start of the program in 2015, we found 40 events with a final mass greater than 100g and 10 for 500g and more. These data are compatible with our initial estimate, but the recovery success is low due partly to agricultural changes from small farms where owners could easily identify "strange" stones to big intensive farms.

The case of 2023 CX1

Asteroid 2023 CX1 was discovered by Krisztián Sárneczky of the Konkoly Observatory on 12 February 2023, just 7 hours before it was due to hit the Earth, which made it possible to track it and calculate its orbit very precisely. Most of the telescopic data was obtained by amateurs. It is important to point out that we had to use data from different networks (FRIPON, GMN, AllSky 7, UKMON) and security cameras to calculate the atmospheric entry parameters. The potential strewnfield was then determined in parallel by several groups. The FRIPON/Vigie-ciel collaboration quickly mobilized its network and set up a field search. 4 stones were thus found by children, 4 others by amateurs and finally only 4 others by scientists who were not even meteorite specialists! In the end, amateurs played a fundamental role in the recovery success at all stages of the event: telescopic and fireball data as well as field searches.

Conclusion

The 7 meteorites found in Europe in the last 5 years would not have been found without the presence of fireball networks to give the alert and calculate the strewnfields. In Europe, we are fortunate to have a number of networks (FRIPON, GMN, AllSky7, DFN, etc.) that enable us to detect these events exhaustively. The success of our research is also largely due to citizen science programs such as Vigie-Ciel, which make it possible to organize effective field searches.

References: [1] Colas et al. (2020) Astronomy and Astrophysics 644, A53; [2] Brown et al (2002) Nature, Volume 420, Issue 6913

How to cite: Colas, F., Zanda, B., Vernazza, P., Malgoyre, A., bouley, S., maquet, L., Steinhausser, A., Egal, A., Gattacceca, J., Birlan, M., Antier, K., Bouquillon, S., gardio, D., Poppe, B., Rowe, J., King, A., Lamy, H., Sylla, S., De Vet, S., and Benkhaldoun, Z.: Update on the FRIPON network and the effectiveness of meteorite recovery in Europe including all fireball networks. The example of the Saint Pierre-le-Viger fall highlights the need for Pro-Am collaboration, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-928, https://doi.org/10.5194/epsc2024-928, 2024.

Very bright meteors, also referred to as fireballs and bolides, are generally produced by objects >10 cm in diameter. While impacts by large asteroids (10s of meters in diameter) are relatively rare, they are not statistically negligible. Such objects carry a destructive potential, as illustrated by the Chelyabinsk event that occurred over a decade ago. Thus, the characterization of these objects is of utmost importance, and helps shed light on why some events might result in more catastrophic outcomes than others. Different sensing modalities can be used in unison to derive various bolide parameters, including its trajectory, entry velocity, and energy deposition, among others. In addition to producing a spectacular display in the sky, bolides are also capable of generating shockwaves. A by-product of shockwaves is a low frequency (< 20 Hz) acoustic wave, or infrasound. Acoustic sensing using infrasound stations installed around the globe has gained momentum over the last decade due to its capability to detect bolides and help estimate their energy deposition irrespective of time of day or cloud coverage. Infrasound is generally used in conjunction with other sensing modalities, such as optical observations, which provide important ground truth information. We present the ground-to-space observations of an energetic bolide that resulted in an airburst over Australia on 20 May 2023. The bolide entered with a speed of 28 km/s over Queensland at 09:22 pm local time, and underwent a catastrophic disintegration at an altitude of 29 km. It deposited energy of ~7.2 kt of TNT equivalent (1 kt = 4.184·10¹² J), making it one of the top 20 most energetic bolides detected by the US government sensors and reported in the JPL/NASA CNEOS database since 1988. The bolide was so bright that it was visible at a distance of 600 km. It saturated ground-based cameras, stifling efforts to derive the full trajectory and obtain photometric measurements. We found infrasound signals at four infrasound stations as far as 6000 km away. The energy estimate derived through infrasound signal analysis is ~7 kt of TNT equivalent, which corroborates the value reported by the CNEOS database. We will present observations of this energetic bolide event and discuss implications for planetary defense and characterization of similar events.

SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.

How to cite: Silber, E., Ronac Giannone, M., Schaible, L., Sansom, E., Devillepoix, H., Edwards, T., Longenbaugh, R., Boslough, M., Bowman, D., Clemente, I., Vida, D., and Šegon, D.: Ground-to-space observations of the 20 May 2023 bolide over Australia, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-602, https://doi.org/10.5194/epsc2024-602, 2024.

On 14/02/2023 at 17:68:29 UT, three all-sky cameras of the PRISMA network detected a bright bolide (IT20230214) over the regions of Puglia and Basilicata in Southern Italy. The bolide traversed the atmosphere for about 5.3 s, with an entry speed of 16.3 ± 0.1 km/s and at an inclination angle of 56.7° ± 0.3°, reaching a minimum absolute magnitude of -11. Projected on the ground, its trajectory began SW of Bari and ended NE of Matera. From the data collected by the PRISMA network, it was possible to fully characterize the meteoroid, which was determined to have a pre-atmospheric mass of 5 – 21 kg, corresponding to a size of 15 – 24 cm. Its pre-atmospheric orbit was determined to be of asteroidal origin, having a moderate eccentricity of 0.54 ± 0.02, an inclination on the ecliptic plane of 14.5° ± 0.2° and a semi-major axis of 2.10 ± 0.07 AU, with a Tisserand’s parameter of 3.51 ± 0.08. According to a photo-dynamic model, simultaneously fitting for the speed and magnitude data, the residual meteorite mass was determined to be 0.10 ± 0.04 kg (4.4 ± 0.7 cm of size). The area of fall of meteorites was estimated to be located north of Matera, in the Basilicata region. In this contribution, we discuss the analysis of the IT20230214 bolide and, in particular, the finding of the Matera meteorite on 17/03/2023, reported by the brothers Mr. Gianfranco and Pino Losignore in Contrada Rondinelle, in the municipality of Matera. With a total recovered mass of 117.5 g, the Matera meteorite was classified as an H5 ordinary chondrite.

How to cite: Barghini, D., Carbognani, A., Gardiol, D., Bertocco, S., Di Carlo, M., Di Martino, M., Falco, C., Fenucci, M., Morelli, M., Pratesi, G., Riva, W., Salerno, R., Stirpe, G. M., and Volpicelli, C. A. and the PRISMA team: The recovery of the Matera H5 ordinary chondrite thanks to the observations of the PRISMA fireball network, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-449, https://doi.org/10.5194/epsc2024-449, 2024.

Imaging and all-sky brightness sensors are common instruments used to acquire light curve data of both fireballs and meteors during their bright flight. This data allows modelling of the ablation process using a photometric model which can be calibrated using light sources with known properties such as stars. 

The imaging systems typically consist of long exposure images which are occulted periodically by shutters, or video cameras[1][2][3]. The light curve sampling rates of these imaging systems is usually between 10Hz and 30Hz. However, they have limited dynamic range causing them to saturate during bright fireballs, and do not have the temporal resolution to identify brief flaring events which limits their use in photometric modelling.

To capture non-saturated bright fireballs at a higher temporal resolution, all-sky brightness sensors using photomultiplier tubes have been deployed to collect data with sampling rates between 500Hz and 5000Hz [4]. Photodiodes have also been explored as a low cost sensor for measuring all-sky brightness at similar sampling rates [5][6][7]. However calibration of the data from these sensors requires external calibrated photometric data acquired from imagery [8]. Operating photomultiplier tubes also requires special design considerations such as protection from the sun during the day, and high voltage power supply designs which can make them difficult to deploy and operate efficiently [9]. 

To address some of the limitations of these instruments, a low cost, all-sky, high frame rate camera system has been developed that captures 12 bit data at 470 frames per second, producing light curves of fireballs and meteors that can be directly photometrically calibrated using stars. The fast exposure period that this frame rate enables and high data bit depth allows the system to image brighter fireballs compared to other video camera systems. The first results show promise as an instrumentation method to produce high temporal resolution photometric data of these events using standard computing hardware, off-the-shelf cameras, and simple deployment.

[1] R. M. Howie, J. Paxman, P. A. Bland, M. C. Towner, E. K. Sansom, and H. A. R. Devillepoix, ‘Submillisecond fireball timing using de Bruijn timecodes’, Meteoritics & Planetary Science, vol. 52, no. 8, pp. 1669–1682, 2017, doi: 10.1111/maps.12878.

[2] D. Vida et al., ‘The Global Meteor Network - Methodology and first results’, Monthly Notices of the Royal Astronomical Society, vol. 506, pp. 5046–5074, Oct. 2021, doi: 10.1093/mnras/stab2008.

[3] F. Colas et al., ‘FRIPON: a worldwide network to track incoming meteoroids’, A&A, vol. 644, p. A53, Dec. 2020, doi: 10.1051/0004-6361/202038649.

[4] P. Spurný, J. Borovička, G. Baumgarten, H. Haack, D. Heinlein, and A. N. Sørensen, ‘Atmospheric trajectory and heliocentric orbit of the Ejby meteorite fall in Denmark on February 6, 2016’, Planetary and Space Science, vol. 143, pp. 192–198, Sep. 2017, doi: 10.1016/j.pss.2016.11.010.

[5] D. Vida, R. Turčinov, D. Šegon, and E. Silađi, Low-cost meteor radiometer. 2015, p. 180. Accessed: May 15, 2024. [Online]. Available: https://ui.adsabs.harvard.edu/abs/2015pimo.conf..180V

[6] S. R. G. Buchan, R. M. Howie, J. Paxman, and H. A. R. Devillepoix, Developing a Cost-Effective Radiometer for Fireball Light Curves. eprint: arXiv:1907.12807, 2019, pp. 123–126. doi: 10.48550/arXiv.1907.12807.

[7]  J.-L. Rault, A little tour across the wonderful realm of meteor radiometry. eprint: arXiv:1911.04290, 2020, pp. 112–117. doi: 10.48550/arXiv.1911.04290.

[8] P. Spurný, J. Borovička, and L. Shrbený, ‘The Žďár nad Sázavou meteorite fall: Fireball trajectory, photometry, dynamics, fragmentation, orbit, and meteorite recovery’, Meteoritics & Planetary Science, vol. 55, no. 2, pp. 376–401, 2020, doi: 10.1111/maps.13444.

[9] R. M. Howie et al., ‘How to build a continental scale fireball camera network’, Exp Astron, vol. 43, no. 3, pp. 237–266, Jun. 2017, doi: 10.1007/s10686-017-9532-7.

How to cite: Giancono, D., Devillepoix, H., and Howie, R.: RadCam: A High Frame Rate Camera for Producing Calibrated Fireball Light Curves at 470 Frames Per Second, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-865, https://doi.org/10.5194/epsc2024-865, 2024.

Background
Jupiter-family comets (JFCs) are distinct low-inclination comets predominantly originating from the Kuiper belt and the scattered disk. These regions, extending beyond Neptune’s orbit, are home to icy primitive bodies that have retained many of their volatile components. JFCs, characterized by their short orbital periods (<20 years) and Tisserand's parameter (2 < T_J < 3), occasionally venture into the inner solar system, where they become visible due to solar heating-induced sublimation. Their trajectories into the inner part of the solar system are characterized by chaotic interactions with Neptune and, in particular, Jupiter. Previous studies have shown that these frequent close encounters with Jupiter give JFCs an exceptionally short dynamical "memory," with Lyapunov lifetimes concentrating towards 50-150 yrs  [1, 2, 3, 4]. The frequent chaotic close encounters provide a very unique dynamical signature to the group that can be used to assess what objects likely originate from the JFC population, even for inactive bodies or meteoroids [5, 6, 3, 7].

Methods
Our study investigates the dynamics and population distribution of JFCs, focusing on their contribution to near-Earth objects (NEOs) and the fireball population. We investigated data from the NASA HORIZONS database (https://ssd.jpl.nasa.gov/horizons/) along with data from multiple of the world`s largest fireball observation networks. We compared the trajectories and physical characteristics of 661 telescopically observed JFCs and 646 fireballs (Fig. 1) observed by the Desert Fireball Network (DFN; https://dfn.gfo.rocks/), European Fireball Network (EFN), Fireball Recovery and InterPlanetary Observation Network (FRIPON; https://fireball.fripon.org/), and Meteorite Observation and Recovery Project (MORP) [8, 9]. The fireball data was limited to objects fitting the Tisserand`s parameter definition of a JFC. The statistical analysis assessed the orbital elements and the frequency of close encounters within the populations over a 10,000 yr integration time period using the Rebound N-body Python library and the IAS15 integrator with all planets included [10, 11]. 

Fig. 1 Fireball data from DFN (blue dots), EFN (red diamonds), FRIPON (green triangle), and MORP (black squares) with 2 < T_J < 3. Also plotted, the 661 JFCs integrated in this study taken from NASA's HORIZONS database are shown as black crosses.}

Results

Our comprehensive analysis reveals significant insights into the nature and origins of objects on JFC-like orbits. We identified nine established meteor showers within the datasets from the DFN, EFN, MORP, and FRIPON networks, accounting for approximately 17% of the JFC-like fireballs. Showers such as the Quadrantids, Southern δ-Aquariids, and α-Capricornids were detected, with varying levels of shower associations across the networks. Interestingly, the October Draconids were identified as the only shower with dynamics consistent with typical JFCs, suggesting it may be the only pristine JFC material in our sample.

At the kilometer scale, the 661 JFCs exhibited frequent close encounters with Jupiter, resulting in rapid and significant changes in their orbits. Interestingly, 30% of near-Earth JFCs showed stable trajectories over 10,000 years, suggesting potential asteroidal contamination consistent with previous studies [6, 12]. However, the dynamics of the JFCs significantly contrast with the centimeter-to-meter scale meteoroids, where the vast majority originate from stable orbits. Only 8-21% of these meteoroids likely experienced close encounters with Jupiter over the 10,000-year integrations, indicating a different source or evolution compared to kilometer-scale JFCs [3, 4].

The Kozai resonance-induced circulation of the argument of perihelion (ω) was observed to protect many meteoroids from close encounters with Jupiter, contributing to their stability. This resonance effect, particularly prevalent among bodies like 96P/Machholz and Marsden group comets, indicates that these objects may contribute significantly to the meteoroid population. Our findings highlight the need for a nuanced understanding of small bodies' sources and evolutionary paths in the solar system. The JFC-like fireballs detected by fireball networks appear to be influenced by asteroidal contamination and survival biases, with only a small fraction consistent with pristine JFC material.

Conclusions
The observed differences in dynamical behavior between kilometer-scale JFCs and centimeter-to-meter-scale meteoroids underscore the varied evolutionary processes affecting these populations and the significance of the size dependence on source region. The findings suggest that the majority of meteoroids on JFC-like orbits are from stable, non-JFC sources, with only the October Draconids showing typical JFC characteristics. These results emphasize the importance of further research into the origins and dynamics of small solar system bodies and the importance of orbital stability and chaos as a metric for interpreting the source regions of meteoroids [3, 4]. 

References

How to cite: Shober, P., Tancredi, G., Vaubaillon, J., Devillepoix, H., Deam, S., Anghel, S., Sansom, E., Colas, F., and Martino, S.: The contribution of Jupiter-family comets to the fireball population, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-338, https://doi.org/10.5194/epsc2024-338, 2024.

Introduction

Almost 1000 meteor showers are known at present. But it is possible to connect the related meteoroid stream to a possible parent body only for a small fraction of them. The so-called D-criteria of the orbital similarity (or dissimilarity) enable us to reveal a possible connection through the similarity of orbits of the comet and such stream particles, which orbits have not been drastically altered by dynamical evolution. By using D-criteria we evaluate the similarity of such orbits to confirm and complete the list of possible parent comets to already known meteoroid streams.

Meteor shower data

The parameters of meteor showers are archived in the Shower Database^a (SD) of the Meteor Data Center (MDC) of the International Astronomical Union (IAU), which is currently undergoing a series of verifications and improvements [1, 2, 3]. One of them is the update of the information about suggested parent bodies of individual meteor showers, as it is incomplete due to various reasons. At the moment, only about 16% of meteor showers in IAU MDC SD has some kind of such information available. For this work, we used 1304 recorded meteor shower solutions downloaded from the IAU MDC SD, which represent 854 meteor showers.

Cometary data

We comprised a file with cometary orbits from three catalogues: the 17th edition of Catalogue of Cometary Orbits [4], orbits from the IAU Minor Planet Center^b and the Jet Propulsion Laboratory cometary catalogue^c. In some cases, the changes of orbital elements are significant, osculating orbits of the same comet calculated for different epochs from all three catalogues were preserved. After omitting the orbits with perihelion values greater than 1.2 au (which orbits cannot be linked with known meteoroid streams via orbital similarity), we compiled a list of 2865 cometary orbits.

Confirmed and newly identified associations

For evaluation of the orbital similarity, we used D_sh [5], D_d [6] and the hybrid D_h [7] functions. The threshold values for all three criteria were identified by using a set of artificial meteoroid orbits with characteristics modeled after the observed orbits and assessing the probability of a random coincidence between each modeled orbit with the orbit of the considered comet.

By application of the above-mentioned criteria, we obtained the following lists with shower-comet associations: 1) shower-comet pairs proposed in the past by various authors which were confirmed by our search, 2)  new shower-comet pairs that have not been (to our knowledge) proposed previously and 3) shower-comet pairs that have been previously proposed by various authors but our search could not identify them. Several cases are discussed individually. These include the new discoveries, cases of a single comet being associated with more than one meteor shower, one meteor shower being associated with more than a single comet and some specific cases of multi-solution showers for which not all of the solutions provided consistent results.

Acknowledgements

This work was supported by the Slovak Grant Agency for Science (VEGA), grant No. 2/0009/22. This research also made use of NASA’s Astrophysics Data System Bibliographic Services, data files from the IAU Minor Planet Center and Jet Propulsion Laboratory tools.

References

[1] Hajduková, M., Rudawska R., Jopek, T. J., Koseki, M., Kokhirova, G. and Neslušan, L., Astronomy and Astrophysics 671, A155, 2023

[2] Neslušan, L., Jopek, T. J., Rudawska R., Hajduková, M. and Kokhirova, G., Planetary and Space Science 235, 105737, 2023

[3] Jopek, T. J., Neslušan, L., Rudawska R. and Hajduková, M., Astronomy and Astrophysics 682, A159, 2024

[4] Green, D. W. E., IAU Circular 8958, 2008

[5] Southworth, R. B. and Hawkins, G. S., Smithsonian Contributions to Astrophysics 7, 261, 1963

[6] Drummond, J. D., Icarus 45, 545, 1981

[7] Jopek, T. J., Icarus 106, 603, 1993

^a https://www.iaumeteordatacenter.org/

^b https://minorplanetcenter.net/

^c https://ssd.jpl.nasa.gov/sb/elem_tables.html

How to cite: Ďurišová, S., Neslušan, L., Hajduková, M., Rudawska, R., and Jopek, T.: Parent comets of meteoroid streams, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-878, https://doi.org/10.5194/epsc2024-878, 2024.

How to cite: Deam, S., Devillepoix, H., and Sansom, E.: A Near-Earth Object Model Calibrated to Earth Impactors, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-987, https://doi.org/10.5194/epsc2024-987, 2024.