The visible rate of meteors is dependent on various local viewing condition during shower peak nights. The interrelationship of the visible fraction of the night sky, radiant elevation and effects of the light pollution on sky brightness confounds outreach efforts to manage realistic expectations for visual meteor observations by the public. The Urban Meteor Map offers a map-based forecast of hourly rates to help make the effects of local viewing conditions more insightful. The project generates maps based on raster data for parameters in the Zenithal Hourly Rate formula. A Digital Surface Model (DSM) covering the Netherlands was used to generate maps of the visible percentage of the sky. At 5 m resolution this DSM offers insights into obstruction by buildings, vegetation and topography. To incorporate effects of light pollution, a national sky brightness map for cloudless nights was converted into Naked Eye Limiting Magnitudes (NELM). Combined with known shower parameters such as population index and radiant height, maps were generated with hourly rates forecasts at local and national scales. Ultimately, observing conditions will remain dependent on the individual observers, their night adaptation and local light interference. The Urban Meteor Map aims to helps raise awareness for the effects of light pollution, and thus promotes exploration of local living environment to seek the best viewing spots for meteor showers. @en

Regmaglypts are shallow depressions on meteorite surfaces formed by ablation processes during atmospheric entry. These features can potentially offer insights in breakup events. However, quantitative methods to analyse regmaglypts have not yet been proposed to date. Here we present the results of a study to evaluate breakup processes during the luminous flight by analysing regmaglypt morphometrics. We developed a novel approach based on a 3D shape model of the Broek in Waterland meteorite that was generated using photogrammetry. We converted sections of the 3D model into a smoothed Digital Elevation Model (DEM) that contained the fracture surfaces adorned with regmaglypts. Lending techniques from terrain analyses, we extracted Land Surface Parameters (LSP) and delineated regmaglypts based on the mean curvature inflection point. The outliers of the regmaglypt population were discarded based on mean and total curvature scatter plots. The mean, profile, tangential, total and Gaussian curvatures were found to be most descriptive of regmaglypt morphologies. Various other curvature types were tested and found to be consistent across the studied regmaglypt population. Using this initial framework, we found that the two regmaglypted surfaces of the Broek in Waterland meteorite appear to be similar. This would reflect similar formative conditions, which we interpret to be most consistent with formation from the same breakup event. Future studies will aim to expand the presented method to regmaglypt populations of other L6 meteorites to understand how surface characteristics can inform us on ablation and breakup processes.@en

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@en

Meteorites are valuable resources in planetary geoscience, since they provide invaluable insights into the composition and origin of planetary bodies, enhancing our understanding of planet formation and the solar system. Despite occurrences of meteorite-dropping fireballs observed every 2 years, traditional field search campaigns in the Netherlands have faced challenges in retrieving fragments. In this presentation we will outline an innovative approach for meteorite recovery through the integration of drones and machine learning algorithms. To enhance search efforts, drones can be used to gain access to restricted fields and increase efficiency. The proposed strategy employs Convolutional Neural Networks (CNNs), a type of machine learning algorithm, to analyze drone imagery and identify potential meteorites. In order to train the artificial neural network, we created an extensive library of image data of fusion-crusted meteorites from the Naturalis meteorite collection placed on a backdrop of various field and soil conditions. The algorithm was tested during a field experiment at Unmanned Valley, Valkenburg, South Holland, using real meteorites and ‘meteorwrongs’ (objects resembling meteorites). During the drone survey we captured images of the target area and then implemented our detection strategy based on machine learning to the new image data set. In this presentation we will discuss the results and future steps.@en

The computation of the dark flight of a bright fireball requires knowledge of the atmospheric parameters. In particular wind and wind direction as a function of height are crucial for an accurate trajectory. In this paper we compare different sources of sounding balloon and model data, and study the effect on the dark flight.@en

Stereoscopic viewing of overlapping aerial image pairs under a mirror-stereoscope has been a common approach to visually study the 3D architecture of landscapes and their constituting landforms. While superseded by digital means for various science applications, the depth perception offered by stereoscopes still has potential to introduce novice learners to the spatial dimensions and relations of landforms, in particular those lacking prior geoscience training. In this presentation I will discuss an application of stereoscopes in planetary science education. Similar to aerial surveying and earth observation, planetary science too relies on expert-driven and semi-automated image interpretation to infer landform and landscape genesis to increase our understanding of planetary evolution. The use of HiRISE stereo image pairs of the Mars Reconnaissance Orbiter allows similar 3D viewing as with conventional aerial photos. We will discuss an activity format involving stereo pairs of the Jezero crater delta, the landing site of the M2020 Perseverance rover and Ingenuity drone, and then review some early results and ideas for future iterations.@en

Assessing and classifying rocks on the basis of their visual traits has been a long standing practise for geoscience fields. For planetary geoscience the interaction with astrogeological materials such as meteorites and impactites contributes to the comprehension of their properties, alteration and, ultimately, solar system formation processes. In the wake of the SARS-CoV-2 (COVID-19) pandemic we explored alternative options to involve meteorites and impactites in remote teaching. Simultaneously, this opened up the integration of meteorites in teaching activities for large groups of learners. We have developed a workflow using Structure from Motion (SfM) photogrammetry to render high-resolution digital 3D models of meteorites and impact rocks. This procedure was used to create a virtual collection with tens of examples that were made publicly accessible in an online environment. The digital 3D models can be inspected by rotating and zooming, while annotations in clickable pop-ups direct users to key features or provide background information and data. We evaluated the user experience and discuss how virtual collections can be created and used for blended learning. Meanwhile, we have explored the use of models in the ‘Delft Meteorite Lab’ in academic teaching, public outreach and science applications. The virtual collection also offers a potential resource to aid the identification of putative meteorite finds by the general public. Looking towards the future, a new ‘Dutch Meteorite Lab’ aims become a national hub for education and research to explore meteorites and meteorite taxonomy based on specimen available in various study collections across the Netherlands.@en

Meteorites offer valuable insights into the composition of asteroids and geological processes contributing to planet formation inside the solar system. Their rapid retrieval after fireball sightings allows this science potential to be used. Finding new meteorites is notoriously difficult due to various complicating factors. A promising search strategy can involve the aerial vantage point of drones (aka: UAV, RPAS). However, drone regulations by the European Union Aviation Safety Agency (EASA) and complex zonation of airspace will impact flight operations, which makes drone-assisted searching in Europe more complex than in e.g. desert environments. Here we present the results of an interdisciplinary desk study, which aimed at proposing a conceptual framework for drone-assisted meteorite searching. We propose the development of an open-source detection and coordination tool to improve aerial assistance by drones during field searches. The design provides drone enthusiasts (referred to as ‘community drones’) and researchers with a platform to coordinate joint drone-based search operations. Image processing is envisioned to take place via a convolutional neural network pipeline, after which high-likelihood locations are identified and manually verified to recover a potential meteorite. This approach will require the development of multiple models to account for variations in soils and vegetation. The tool supports multi-drone coordination, providing path planning functionality and support for a broad range of (commercially) available drone models (e.g. DJI) and sensor types (e.g. RGB, thermal). Considering EASA drone regulations, the use of the DJI Mini 3 Pro is favoured as an accessible community drone. Follow-up research, implementing the proposed conceptual approach, should validate the design presented here and highlight practical areas of improvement.@en

The long-axis orientation of elongated sand grains in aeolian systems is dependent on saltation of grains and orientation to the dominant wind direction. This relationship can be used to understand the dynamic environment on Mars based on close-up images of the surface taken by microscope cameras. We perform(ed) experiments at the Aarhus Mars Simulation Wind Tunnel, a closed circuit, low-pressure wind tunnels that allows saltation to be studied at different pressures and friction velocities. Close-up images taken of the sandbed were used with image segmentation methods to delineate grains and determine the preferred orientation of particles. Similar methods have been used on thin sections taken from well-studied and oriented sediments on Earth. Our study aims to generate and study oriented sediments under Martian analogue conditions to investigate how grain orientation (imbrication) is modulated in low pressure environments. We will discuss the effects of different air pressures and friction velocities on the observed preferred orientation of particles in the sandbed and evaluate the implications for aeolian processes in different atmospheric conditions. While tailored to active aeolian sediments, this method could offer insights for interpreting lithified samples such as sand stone outcrops studied by Mars rover to investigate aeolian processes in the past. @en

We report on the design of a meteorite impact simulator and evaluate the first results. Artificial meteorites were dropped on the ground with realistic terminal velocities. The soil disturbance and impact pit remained recognizable for approximately 3 months. These experiments foster our understanding of impact dynamics in soft deformable top soils, and contribute observables to improve the success rate of meteorite search campaigns.@en