EU-ESA Workshop on Meteor Observations for Planetary Defence

3 Nov 2026, 09:00 → 5 Nov 2026, 18:00 Europe/Amsterdam

Petralia Sottana, Sicily

Juan L. Cano (ESA), Maxime Devogele (ESA NEOCC), Richard Moissl, Francisco Ocaña, Thea Dethlefsen (European Commision)

Rational

Small imminent impactors are now routinely being detected before impact and allow the support of a new collaborative model for planetary defence. Most pre-impact cases to date are in the metre-range where we can combine pre-entry telescopic observations with atmospheric measurements from fireball networks, radar, infrasound, and space-based sensors. This end-to-end chain provides a unique testbed for linking orbit, entry behavior, and physical properties within a single event. Europe has strong capabilities across all these techniques, but the interfaces between communities remain fragmented. This workshop brings them together to build workflows from detection to characterisation to fireball analysis to combined interpretation, improving both near-term operational readiness and the scientific basis for assessing future impact threats. 

Workshop goals

• Map the end-to-end European workflow for imminent impactors: detection, rapid telescopic follow-up, atmospheric observation, and integrated post-event analysis. 
• Define coordination interfaces between communities to enable rapid multi-network response. 
• Establish how combined pre-impact and atmospheric datasets can constrain trajectory, physical properties, and impact effects for future planetary-defence readiness. 
• Build sustained communication channels between the astronomer/planetary-defence comunity and the meteor community, including regular cross-community exchanges, shared terminology, and clear points of contact for imminent-impact events. 

 

Tentative sessions:

• Radar observations
• All sky camera networks
• Infrasound and Seismics
• Other opportunistic sensors
• Trajectory reconstruction, Orbit determination, and Strewn fields
• Spectroscopy & Physical properties of fireballs 
• From meteorites to planetary defence

 

Privacy notice

Tuesday 3 November

Welcome, workshop objectives and practical information

Meteor observations and planetary defence: context and objectives

1 ESA’s PDO activities related to meteor/fireball observations

Activities of ESA’s Planetary Defence Office (PDO) encompass the study of meteoroids, the smaller end of the near-Earth object size distribution. In consequence, our three main pillars are therefore related to fireball observations.

On one hand, the observational pillar deals with imminent impactors, objects at the edge between meteoroids and asteroids which are observable from space right in the few hours before the impact. We do follow-up observations of very close approaches and impactors. We are currently researching the effect of LSST discoveries in the field (Frazer et al., 2026). So far, in 2026 we have investigated the impacts of 2026 JN4 and 2026 RW1, the 12th and 13th predicted impactors.

The orbit determination and assessment pillar runs our impact monitor systems. In the NEOCC operational workflow, short-term impacts are assessed by Meerkat. In case of an event with high impact probability, Aegis provides corridor information and we have developed a method to calculate pre-impact meteorite strewn field predictions (Moscati et al. 2026).

In the mitigation pillar we address all the topics that are relevant for reducing the harm in case on an impact. In that sense, the study of fireballs is essential for understanding the dynamics of these objects in the atmosphere. Apart from the activities entrusted by the EC on object characterisation, impacts on the moon, etc., we work on the detection of the fireballs themselves with the development of a pipeline for satellite-based detection of fireballs with Meteosat Third Generation - Lightning Imager data (Rubbrecht et al., 2026, in prep.). We also run 3 all-sky cameras to contribute with observational fireball data and provide material for communications.

The Information provision pillar manages the NEOCC web portal. The website provides the public reliable information on past impactors and imminent impactors. It also hosts the Fireball Information System (FIS) providing a long-term archive of the German part of the ‘European Network (EN)’ of fireball cameras.

Transversal to all the operational tasks, we have some activities to build better knowledge of the meteoroids. Using fireball detections, we are modelling flux density as an input for asteroid population modelling (Frühauf M., PhD dissert. in prep.). We also do active research on NEO science (dark comets, meteorite recovery field trips…) and participate in planetary defence communication and outreach activities.

Speaker: Francisco Ocaña (ESA ESAC)

2 From Meteors to Planetary Defense: Current Knowledge, Recent Events, and Gaps

Meteor observations provide a unique opportunity to characterize small near-Earth objects as they interact with the atmosphere, providing information that cannot be obtained from telescopic observations alone. In recent years, advances in optical networks, trajectory reconstruction, fragmentation modeling, and meteor physics have significantly improved our ability to infer the physical properties and atmospheric interaction of meteoroids. This presentation will review the current state of meteor observations and modeling, with particular emphasis on their relevance to planetary defense. We will discuss what can currently be inferred from meteor observations, the physical models used to describe atmospheric entry and fragmentation, and the main uncertainties that remain. Recent well-observed events, including 2022 WJ1, 2023 CX1, and the Novo Mesto fireball, will be used for illustration. We will also discuss the potential contribution of space-based observations, including the scientific opportunities offered by global coverage and ultraviolet spectroscopy, and how future observational capabilities could complement existing ground- and space-based systems.

Speaker: Eloy Peña-Asensio (Universitat d'Alacant)

3 Open discussions

10:30 Coffee break

Radar and seismic observations of atmospheric entries

4 Using radars to probe space objects across 8 orders of magnitude in size

High-power large-aperture (HPLA) radars are a unique way to probe the population of small bodies near Earth as they can observe both very small particles, down to $10^{-5}$ meters in size, and very large up to hundreds of meters. The smallest particles, called meteoroids, are observable as they enter the Earths atmosphere and produce the phenomenon known as a meteor. Detection of these are possible because the meteoroids produce a plasma which stretch much larger sizes than the particle itself during ablation, and this plasma can scatter the incoming radio waves from the radar. Towards larger sizes, number densities drop fast, so meteors get less frequent and HPLA radars less efficient. Here, optical systems shine (pun intended) with their wide fields of view and often cheaper price than a HPLA facility. But at this point, radars can instead scatter radio waves off the small body itself. Using very long integration times, we can detect meteoroids and asteroids at very long distances and even create radar images of them. Now, there will soon be a new HPLA radar in operation in northern Fenno-Scandinavia called EISCAT_3D. It will be the worlds most advanced radar of its kind. EISCAT_3D consists of a phased array transmitter/receiver site near Skibotn in Norway, one remote receiver site near Kiruna in Sweden and another one near Karesuvanto in Finland. Each site comprises an antenna array with 5.000--10.000 elements. The Skibotn site has a combined 3.37 MW pulsed transmitter power (up to 25\% duty cycle) at an operating frequency of 233 MHz. This unique instrument will enable meteor head echo observations of unprecedented quality while also enabling novel observations of objects in near Earth space, such as minimoons and asteroids.

Speaker: Daniel Kastinen

5 Observations of fireballs and space debis with the BRAMS network

BRAMS (Belgian RAdio Meteor Stations) is a Belgian forward-scatter radio network dedicated to meteor observations, consisting of a dedicated transmitter and more than 50 receiving stations located in Belgium and neighbouring countries. The transmitter emits a continuous-wave signal at 49.97 MHz with a power of approximately 350 W. As a consequence of the forward-scatter geometry, the range to a meteor echo is not measured directly, and the reconstruction of meteoroid trajectories and velocities relies on time delays between echoes observed at multiple receiving stations, complemented by pre-t0 phase curves (Balis et al., 2025).

These techniques rely on specular reflection of radio waves from ionized meteor trails, an assumption that is generally valid for underdense and intermediate meteor echoes. For fireballs, however, trail echoes often become complex and turbulent and may exhibit non-specular reflections. Some fireballs also produce head echoes, which can provide additional constraints on their trajectories and velocities.

We present preliminary results on the determination of fireball velocities and trajectories using two different methods. The first is based on the frequency-time slope of meteor head echoes observed at several receiving stations. This approach is challenging because the usable frequency range of the head echo is often limited by overlap with the trail echo, contamination by strong aircraft reflections, or a low signal-to-noise ratio (SNR) in the upper part of the echo. The second method uses the Fresnel transform introduced by Elford (2004). To assess the quality of the derived velocities and trajectories, we analyse
BRAMS observations of well-documented fireball events simultaneously observed by the FRIPON optical network (Colas et al., 2020).

On 27 August 2024, the uncontrolled re-entry of a Starlink satellite produced a bright fireball that was widely observed by the public, with more than 450 witness reports submitted to the IMO fireball database. Although the initial part of the trajectory was located south of the BRAMS network, over northern France, the event was clearly detected by several receiving stations. We apply the same two methods to the associated head echoes to constrain the velocity and trajectory of the satellite. The results are compared with trajectories derived from visual observations, TLE data, and seismo-acoustic observations (Eickhoff et al., 2026).

These preliminary results illustrate the potential of the BRAMS network for future fireball and space-debris observations, as well as the remaining methodological challenges that need to be addressed.

Balis J., Lamy H., Anciaux M., Jehin E., De Keyser J., Kas nen D., Brown P. G., Enhanced Meteoroid Trajectory and Speed Reconstruc on Using a Forward Sca er Radio Network: Pre-t0 Phase Technique and Uncertainty Analysis, Radio Science, Volume 60, Issue 8, 2025

Colas, F. et al, FRIPON: a worldwide network to track incoming meteoroids. Astronomy & Astrophysics, Volume 644, 2020.

Eickoff, D. Et al, Re-entry and burn up of Starlink-2382 satellite: estimating trajectory and ablation coefficient from acoustic and coupled seismic waves, Geophysical Journal Interna onal, 246, 2026.

Elford, W.G., Radar observa ons of meteor trails, and their interpretation using Fresnel holography: a new tool in meteor science, Atmospheric Chemistry and Physics, 2004.

Speaker: Herve Lamy (Space Physics, BIRA-IASB, Avenue circulaire 3, 1180, Brussels, Belgium)

6 From natural hazards to artificial ones: tracking and characterising space debris re-entries using seismic data

Many of the tools used to track meteoroids entering the atmosphere can be adapted to characterise the highly complex re-entries of artificial spacecraft which are now entering the atmosphere multiple times per day; with each posing a risk to life and infrastructure both in the air and on the ground. In this talk I will show how seismic data enable us to reconstruct the trajectory of debris re-entries, estimate their speeds, and characterise their fragmentation. I will also discuss how seismic data can be used to track objects during their terminal phase of re-entry, when other methods such as optical and radar tracking struggle. Finally, I will discuss how we are using test events such as the Artemis II re-entry to calibrate our measurements, and new technologies such as distributed acoustic sensing to achieve better sensor coverage.

Speaker: Benjamin Fernando (University College London)

7 Open discussions

12:30 Lunch

Optical fireball networks and the small-impactor population

8 European Fireball Network: Complex characterization of fireballs

The European Fireball Network (EN) was officially established in 1968 after fireball stations in western Germany joined the Czechoslovak Fireball Network, which had been in operation since 1964. Various stations in countries of central and western Europe were used thorough the history of the network. The techniques developed from manually operated convex mirror cameras to current autonomous digital observatories, but all-sky photography remained the main tool. The headquarters have always been at the Ondřejov Observatory near Prague.

Currently, the core of the network consists of 16 stations in the Czech Republic, 4 in Slovakia, one in Austria and one in Germany. Apart for all-sky photography, also spectral photography, video observation covering 24 hours per day, and radiometric recording with 5000 samples per second are used. The Dutch Meteor Network in the Netherlands, Belgium, and northwestern Germany is officially associated with EN and uses similar techniques. The goal of the network is not to cover an enormously large territory and produce huge amount of data but to provide precise and complex characterization of fireballs of absolute magnitude –3 and brighter. The obtained data include trajectories, velocities, dynamics, photometry, orbits, fragment imaging, and spectra for bright fireballs. The data are used for modeling the meteoroid fragmentation and ablation in the atmosphere, deriving physical properties and composition of meteoroids, studying meteoroid streams and for other purposes. In rare cases resulting in meteorite falls, we determine the corresponding strewn field. More than ten different meteorites have been recovered in central Europe in the last decade thanks to the observations and computations by the EN team. The analysis of the fireball caused by the imminent impactor 2024 BX1 confirmed the reliability of the EN results, including the orbit, strewn field and in this case also the meteorite type inferred from fireball spectrum.

Speaker: Jiří Borovička (Astronomical Institute of the Czech Academy of Sciences, Ondřejov Observatory, Czech Republic)

9 Ten Years of Observations of the Italian PRISMA Fireball Network: Results and Perspectives

The recovery of freshly-fallen meteorite specimens, enabled by the precise observation of fireballs in the Earth’s atmosphere, is the only other method - beyond sample-return missions - to gather asteroid samples as pristine as possible. To this purpose, the PRISMA project (Prima Rete Italiana per la Sorveglianza sistematica di Meteore e Atmosfera) was born in 2016 and, since then, has deployed a fireball network dedicated to the observation of fireballs and bolides and to the recovery of freshly-fallen meteorites on the Italian territory [1,2]. The project started as a partner of the international collaboration FRIPON [3] and, to date, the network counts over 100 all-sky cameras and involves more than 80 participating institutions. The PRISMA network and collaboration are coordinated by INAF, the Italian National Institute for Astrophysics.

Since 2016, PRISMA has observed more than 3000 bright meteors. A complete and original data analysis pipeline has been developed, mainly to perform an automatic astrometric and photometric calibration of each camera and to compute the trajectory of each observed fireball, estimating the value of the most relevant physical and orbital
parameters of the meteoroid [4]. To date, PRISMA observed 11 fireballs that were determined to be meteorite-droppers and for which a strewn-field was computed, for the search of freshly-fallen meteorites, on the Italian territory. In particular, the observations and data analysis of PRISMA allowed for the recovery of two meteorites, namely Cavezzo [5,6] (01/01/2020, L5-an, 55.3 g) and Matera [7] (14/02/2023, H5, 117.5 g).

In this contribution, we will present the latest updates on the development and implementation of the data reduction pipeline and on the analysis of the PRISMA observation dataset, as we are currently working towards the release of a first version of the PRISMA fireball database that will encompass the raw data and results of the first ten years
of observations.

References
1. Gardiol D. et al., PRISMA, Italian network for meteors and atmospheric studies, in: Proceedings of the IMC, Eds. Roggemans, A.; Roggemans, P., IMO, 2016, Egmond, the Netherlands; pages: 76-79.
2. Gardiol D. et al., News from the Italian PRISMA fireball network, in: Proceedings of the IMC, Eds. Rudawska, R. et al., IMO, 2018, Pezinok-Modra, Slovakia; pages: 81-86.
3. Colas F. et al., Astronomy & Astrophysics 2020, 644, A53.
4. Barghini D., Meteorites recovery and orbital elements of Near-Earth Objects from the observation of bright meteors: Scientific exploitation of the PRISMA fireball network data and of the missions of the JEM-EUSO program, PhD Thesis, Università degli Studi di Torino, Torino, 2023.
5. Gardiol D et al., Monthly Notices of the Royal Astronomical Society 2021, 501, 1215-1227.
6. Pratesi G. et al., Meteoritics & Planetary Science 2021, 56, 1125-1150.
7. Pratesi G. et al., Meteoritics & Planetary Science 2025, 60, 2125-2148.

Speaker: Daniele Gardiol (Istituto Nazionale di Astrofisica - Osservatorio Astrofisico di Torino, Via Osservatorio 20, Pino Torinese, Italy)

10 Preliminary Results for the Velocity Distribution and Fireball Flux Density of Sporadics derived from FRIPON Data

FRIPON is a fully automated network of optical all-sky cameras monitoring meteoroid entries into the Earth's atmosphere. Using these data, we present preliminary results on the velocity distribution and the fireball flux density of sporadics in the mass range of approximately 10⁻³ to 10¹ kg. We also discuss the methodology, including the applied de-biasing.

Speaker: Michael Frühauf

11 Open discussions

15:30 Coffee break

Optical fireball networks and the small-impactor population

12 The Global Meteor Network as a Planetary Defence Asset: Fireball Trajectories, Orbits, and the Physical Structure of Small Impactors from Citizen-Operated Cameras

The Global Meteor Network (GMN) is a distributed optical fireball network of more than 1,600 cameras in over 45 countries, operated by volunteers using consumer off-the-shelf security cameras and Raspberry Pi computers running the open-source RMS software. Trajectories, orbits, and calibrated photometry are published daily, and the full analysis toolchain is open source and independently reusable.
This contribution reviews what GMN can measure during an impactor response, and how well. The GMN provides multi-station trajectory reconstruction, orbit determination with numerical integration to pre-impact elements, absolute photometric lightcurves, semi-analytic fragmentation modelling that constrains bulk strength and fragment mass distribution, and dark-flight and strewn-field prediction using the best available wind models.
We illustrate performance with three imminent-impactor and meteorite-dropping cases. For 2022 WJ1, trajectories derived from meteor cameras and from MPC astrometry agreed to within 40 m, and fragmentation modelling independently supported a decimetre-scale, ordinary-chondrite-like body. Novo Mesto and 2023 CX1 demonstrate what fireball data reveal about internal structure: Novo Mesto disrupted abruptly near 35 km, shedding over 80% of its mass around 3 MPa, while 2023 CX1 catastrophically disrupted near 28 km and released 98% of its kinetic energy in a fraction of a second. Both dropped L chondrites, indicating a class of small impactors that fails at low dynamic pressure, directly relevant to airburst hazard assessment.
Beyond single events, GMN's homogeneous orbit and flux database constrains the centimetre-to-metre impactor population, its orbital sources, and seasonal detection biases.
We conclude with the reliability limits of each product and what would be required to operationalise GMN for planetary defence response: rapid-response tasking, reduced latency, standardised uncertainty reporting, and a sustained support model for an infrastructure currently sustained by volunteers.

Speaker: Denis Vida (Department of Physics and Astronomy, Institute for Earth and Space Exploration, Western University, London, Ontario, Canada)

13 Open discussions

Radar and seismic observations of atmospheric entries

14 Technologies using bolide shockwaves to infer impactor characteristics: science opportunities, strengths and weaknesses.

Speaker: Peter Brown

15 Open discussions

Wednesday 4 November

Fireball observations from space: detection and calibration

16 Automated fireball detection and characterisation from space with MTG-LI

The Meteosat Third Generation Lightning Imager (MTG-LI) has been operational since late 2024, providing continuous optical measurements optimised for lightning detection over Europe, Africa, and the Atlantic region. Beyond its nominal objective, MTG-LI has also demonstrated sensitivity to the optical flashes produced by fireballs.

ESA’s Planetary Defence Office (PDO), in collaboration with EUMETSAT, is adapting the MTG-LI lightning detection pipeline for the automated detection and characterisation of fireball signals. For this purpose, we are developing the LI Fireball Tracker (LIFT), a tool that systematically distinguishes fireball-induced flashes from lightning and extracts key fireball characteristics, including their brightness evolution and projected trajectories. These capabilities are being integrated into a data pipeline with the ultimate objective of delivering a comprehensive operational PDO fireball portal.

A key component of this effort is the recalibration of MTG-LI measurements from their nominal lightning-radiance framework to physically meaningful fireball energies. This will enable the conversion of observed optical signals into estimates of fireball luminosity and energy, providing a consistent basis for characterising fireball events and comparing observations across different events and instruments.

In ongoing collaboration with NASA, MTG-LI complements the fireball monitoring capabilities of the Geostationary Lightning Mapper (GLM) by extending coverage to the Eastern Hemisphere, enabling near-global geostationary observation of fireball activity. The fields of view of the two instruments also overlap, allowing for joint detection of the same events. This stereo viewing geometry facilitates the reconstruction of fireball trajectories in three dimensions (Silber et al., 2026), providing a pathway towards the determination of their pre-atmospheric orbital elements.

This emerging application of lightning imagers aboard weather satellites provides valuable new data for meteor science and planetary defence, while synergising with existing ground-based meteor networks to enhance event characterisation and observational coverage.

Speaker: Niels Rubbrecht (ESA ESOC, Planetary Defence Office, Robert-Bosch-Str. 5, 64293 Darmstadt, Germany/EUMETSAT, Eumetsat Allee 1, 64295, Darmstadt, Germany)

17 Fireballs in the lightning: Geostationary satellites as calibrated planetary-defence sensors

Every day, geostationary weather satellites record millions of lightning flashes. Hidden among them are bolides: meteoroids and small asteroids entering the atmosphere, seen continuously over whole hemispheres by day and night, whatever the weather. GOES-GLM has watched the Americas since 2017, and since 2024 the Lightning Imager on Meteosat Third Generation has opened the same window over Europe, Africa and the Atlantic. Yet these instruments were built for thunderstorms, not fireballs, and they see bolides through a narrow slit of the spectrum. How far can we trust what they record? We combine the European and American imagers with the US Government fireball record to ask what lightning sensors can tell us about incoming impactors: how bright, how fast, and how often. We present what the two satellites agree on and where they disagree, and what a European bolide record could bring to planetary defence.

Speaker: Simon Anghel

18 Open Discussions

10:30 Coffee break

Imminent impactors: discovery, alerts and coordinated response

19 Imminent Impactors: Are We Ready

Meteor science has traditionally been done by observing short transient events for which there is no warning for. We are in an era where we detect some asteroids before they impact. And, coincidentally, these metre-scale objects are in the sweet spot for meteorite survival. Imminent impactors directly close the loop between the small Solar System body science driven by telescopes and meteor/meteorite science. In this talk I will give an outlook on how many asteroid impacts we can expect to get warning for over the next few years. I will then discuss why they are interesting objects to focus on, developing three aspects they enable: science, planetary defence, and public outreach. Finally, I will suggest ideas of what could be worthwhile infrastructure and instrumentation investments over the next decade to observe these impacts, and what strategies can be developed to involve the public as citizen scientists.

Speaker: Hadrien Devillepoix

20 Meerkat: An Operational Software System for Automated Imminent Impactor Detection and Community Alerting

The increasing discovery rate of near-Earth objects requires software systems capable not only of orbit analysis, but also of continuous data ingestion, automated decision-making, and rapid dissemination of actionable information. We present Meerkat Asteroid Guard [1], the European Space Agency's operational imminent impactor monitoring system, developed and maintained at the Near-Earth Object Coordination Centre (NEOCC). Since becoming operational in 2021, Meerkat has contributed to the identification and follow-up of all known pre-impact asteroid discoveries detected during its operational lifetime.

Meerkat continuously monitors newly reported objects on the Minor Planet Center's Near-Earth Object Confirmation Page, automatically detecting updates, retrieving observations, and executing orbit determination and impact assessment workflows. The system produces a range of data products, including impact probabilities, uncertainty visualizations, follow-up pointing recommendations, impact corridors, and object classification summaries, which are distributed to analysts and observers in near real time.

This contribution focuses on the operational design and the alerting framework. Through email notifications, messaging systems, and automated phone calls, Meerkat acts as a catalyst for rapid international follow-up campaigns. Through dedicated mailing lists, alerts are distributed to professional and amateur astronomers across multiple continents, enabling rapid follow-up observations to refine orbit solutions and confirm or rule out potential impact scenarios.

[1] https://doi.org/10.1007/s40295-025-00560-0

Speaker: Francisco Ocaña (ESA ESAC)

21 ESA’s Flyeye-1 Telescope: A Wide-Field Survey for Imminent Impactors at Mt. Mufara

The Flyeye-1 is the first in a planned network of wide-field survey telescopes developed by the European Space Agency (ESA) to strengthen Europe’s capability to discover Near-Earth Objects (NEOs). Its permanent home will be the observatory currently under construction at Mt. Mufara in the Madonie mountains of Sicily.

The Flyeye’s significance to the meteor community lies at the first step of any imminent impactor event: the discovery. Metre-scale objects only become bright enough to detect in the final hours to days before they reach Earth, so finding them means covering as much sky as possible, as often as possible. Flyeye-1 is built for exactly this, with 16 optical channels that together image about 45 square degrees per exposure, allowing the whole visible sky to be covered every three to four nights. Every impactor found this way becomes a predicted fireball, giving observers advance notice of when and where to look.

We present the status of Flyeye-1 following its first round of integration and end-to-end testing at the ASI Space Geodesy Centre in Matera. After the on-sky alignment procedure, the realigned optical channels (6 of 16 so far) reach a mean half-flux diameter of about 4.7 arcsec. Plate solutions against Gaia DR3 give residuals of about 0.65 arcsec, and the image timestamp bias measured with GNSS satellites is 30 ± 14 ms. A first estimate of the 5-sigma limiting magnitude is about 19.4 in 60 s exposures, a preliminary value obtained under light-polluted skies. We also describe the first end-to-end runs of the full observation chain, from scheduling and image acquisition to data processing.

Finally, we report on the progress of the Mt. Mufara observatory and the ongoing relocation of the telescope to its permanent site, and outline the expansion of the network with Flyeye-2 in the Southern Hemisphere.

Speaker: Dora Föhring (ESA NEOCC)

12:25 Lunch and visit to Monte Mufara

Thursday 5 November

From fireball observations to physical properties and meteorite recovery: Spectroscopy and physical properties of Fireballs

22 From Fireballs to Impactors: AMOS Meteor Network and Spectroscopy for Planetary Defence

The All-sky Meteor Orbit System (AMOS), developed at Comenius University in Bratislava, is a global network of autonomous meteor cameras designed to investigate the dynamical and physical properties of meteoroids entering the Earth's atmosphere up to about +3 magnitude. Combining multi-station video observations with meteor spectroscopy (AMOS-Spec), the network provides atmospheric trajectories, pre-atmospheric heliocentric orbits, photometric characteristics, and information on meteoroid composition.
This presentation will highlight selected AMOS results, focusing on bright fireballs and the identification of potentially meteorite-dropping events. Meteor emission spectroscopy provides important constraints on the composition and physical diversity of incoming material. Combined with trajectory reconstruction and orbital analysis, these observations help distinguish different meteoroid material and characterization.
Special attention will be given to the relevance of AMOS observations for planetary defence, including the characterization of small impactors, estimation of their physical properties, and prediction of potential meteorite fall areas. The presentation will discuss the capabilities and limitations of ground-based meteor networks and the potential integration of optical and spectroscopic observations into coordinated planetary defence activities.

Speaker: Juraj Toth

23 Automated Meteor Impact Classification for Planetary Defence

Meteor observation networks are generating increasingly large,
precise, and geographically distributed datasets of meteoroid
atmospheric entries. These observations offer an opportunity to move
beyond detection and trajectory reconstruction towards automated
physical characterisation and classification of incoming bodies. The
α–β method (Gritsevich 2009) provides a physically grounded and
computationally efficient way for interpreting atmospheric-entry
dynamics and assessing their relevance to planetary defence (e.g.
Gritsevich et al. 2012; Sansom et al. 2019). Its extension to
realistic atmospheric conditions (Lyytinen and Gritsevich 2016) makes
it well suited to the automated analysis of large fireball datasets.
This contribution explores how integrating the method with automated
detection and trajectory analysis can enable rapid, consistent
assessment of atmospheric deceleration, ablation, penetration, and
potential meteorite survival.

The α–β method characterises meteoroid atmospheric entry using two
dimensionless parameters, α and β, which describe the coupled effects
of atmospheric deceleration and mass loss. The parameter α primarily
reflects the ballistic behaviour and degree of atmospheric
deceleration, while β characterises the relationship between
aerodynamic energy loss and ablation. The parametrisation is further
extended through the shape-change coefficient μ, which accounts for
changes in the effective cross-sectional area and evolution in the
shape of the body as mass is lost during atmospheric flight. Together,
α, β and μ allow fireballs with different sizes, velocities, entry
angles and physical characteristics to be compared within a common
parameter space. The method is successfully used by the observing
networks wordwide, including the Finnish Fireball Network, the Desert
Fireball Network, the Spanish Meteor Network, the BOOTES network in
cooperation with the University of Málaga, the Polish Fireball Network
and FRIPON. The applications include fireball classification,
estimation of pre-atmospheric mass and bulk density, rapid
identification of meteorite falls and prioritisation of events for
detailed follow up analysis.

We highlight accessible opportunities to integrate the method into
reproducible, open-access analysis pipelines, harmonise
classifications across observing networks, and develop collaborative
datasets and joint publications. These efforts would help establish
standardised procedures for translating routine meteor observations
into physically interpretable parameters and prioritised event
classifications. This provides a scalable pathway towards more
efficient fireball analysis and improved characterisation of small
near-Earth objects entering Earth's atmosphere, strengthening the
connection between automated meteor monitoring and planetary-defence
objectives.

Speaker: Maria Gritsevich (Instituto de Astrofísica de Andalucía (IAA-CSIC))

24 From discovery to disruption: reconstructing the journey of asteroid 2023 CX1

On February 13, 2023, asteroid 2023 CX1 entered Earth's atmosphere over the English Channel, approximately seven hours after its discovery. The event produced a bright fireball observed across western Europe and led to the recovery of the Saint-Pierre-le-Viger meteorites in Normandy, France. This rare combination of pre-impact observations, atmospheric measurements, and laboratory analyses provided an exceptionally well-constrained case study of how a small asteroid deposits its energy in the atmosphere.
By combining telescopic observations, dynamical modelling, optical and seismo-acoustic measurements, strewn-field modelling, and meteorite analyses, we reconstructed the asteroid's likely origin, trajectory, physical properties, and fragmentation behaviour. Comparing results from different instruments and laboratories also revealed discrepancies in some of the measurements and analyses, allowing us to identify limitations and improve existing methods.
2023 CX1, a nearly spherical object approximately 72 cm in diameter and 650 kg in mass, underwent a sudden catastrophic disruption at an altitude of 28 km, under a dynamic pressure of approximately 4 MPa. Rather than depositing its energy progressively along its trajectory, the body released up to 98% of its total energy within a concentrated atmospheric region. Hydrodynamic simulations show that this rapid energy deposition produces a more spherical shock wave than would result from gradual fragmentation, which could increase the ground area exposed to high overpressures for larger impactors.
We will discuss the observational constraints, remaining uncertainties, and implications of these results for modelling atmospheric fragmentation and assessing future impact hazards.
*This presentation is based on the collaborative study published in Egal et al. (2025, Nature Astronomy), co-authored by :
Denis Vida, François Colas, Brigitte Zanda, Sylvain Bouley, Asma Steinhausser, Pierre Vernazza, Ludovic Ferrière, Jérôme Gattacceca, Mirel Birlan, Jérémie Vaubaillon, Karl Antier, Simon Anghel, Josselin Desmars, Kévin Baillié, Lucie Maquet, Sébastien Bouquillon, Adrien Malgoyre, Simon Jeanne, FRIPON International Team, Jiří Borovička, Pavel Spurný, Hadrien A. R. Devillepoix, Marco Micheli, Davide Farnocchia, Shantanu Naidu, Peter Brown, Paul Wiegert, Krisztián Sárneczky, András Pál, Nick Moskovitz, Theodore Kareta, Toni Santana-Ros, Alexis Le Pichon, Gilles Mazet-Roux, Julien Vergoz, Luke McFadden, Jelle Assink, Läslo Evers, Daniela Krietsch, Henner Busemann, Colin Maden, Lisa Maria Eckart, Jean-Alix Barrat, Pavel Povinec, Ivan Sýkora, Ivan Kontul’, Oscar Marchhart, Martin Martschini, Silke Merchel, Alexander Wieser, Matthieu Gounelle, Sylvain Pont, Pierre Sans-Jofre, Sebastiaan de Vet, Ioannis Baziotis, Miroslav Brož, Michaël Marsset, Jérôme Vergne, Josef Hanuš, Maxime Devogèle, Luca Conversi, Francisco Ocaña, Luca Buzzi, Dan Alin Nedelcu, Adrian Sonka, Florent Losse, Philippe Dupouy, Korado Korlević, Dieter Husar, Jost Jahn, Damir Šegon, Mark McIntyre, Ralf Neubert, Pierre Beck, Patrick Shober, Anthony Lagain, Darrel Robertson, Peter Jenniskens, Olivier Hernandez.

Speaker: Auriane Egal (Planétarium de Montréal, Espace pour la Vie, Montreal, Quebec, Canada)

25 Open discussions

10:30 Coffee break

From fireball observations to physical properties and meteorite recovery

26 From orbit to ground: pre-impact meteorite strewn field predictions for imminent impactors and meteorite recovery.

The flux of meteoroids reaching the Earth is continuous, ranging from microscopic
grains to occasional metre and decametre scale bodies. The smallest ones fully ablate in the upper atmosphere, whereas sufficiently large or strong objects survive entry and deposit fragments on the ground as meteorites. Predicting where these fragments land, and reconstructing the atmospheric trajectory and fragmentation sequence that produced them, is central both to hazard assessment and to the recovery of freshly fallen material. The accuracy of such predictions, however, remains limited by poorly constrained fragmentation processes and by sparse, heterogeneous observational coverage of individual events. Traditional strewn field simulations rely on detailed fireball data and event-specific assumptions on fragment masses, aerodynamics, and breakup. These approaches are effective for well-instrumented events, but their applicability degrades rapidly when observations are sparse, often resulting in huge uncertainties. We present an ab initio framework predicting strewn fields of near-Earth asteroids directly from pre-impact orbital solutions. It propagates luminous trajectory and dark flight using a physics-based translational dynamics model and realistic atmospheric conditions, without requiring fireball triangulation or event-specific tuning. Validation against recent asteroid falls with recovered meteorites shows agreement with observations, with nominal solutions reproducing fall locations within 100-200 m. The new method has been integrated into the ESA Aegis pipeline, which now enables hours-ahead computation of impact locations, supporting recovery efforts, minimizing contamination, and, where warranted by object size and predicted ground hazard, civil-protection decision making.

Speaker: Anna Moscati

27 Open discussions

12:30 Lunch

Open discussions and final thoughts

15:30 Coffee break

Open discussions and final thoughts