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Aims. The Fireball Recovery and InterPlanetary Observation Network (FRIPON) scientific project was designed to overcome this limitation. This network comprises a fully automated camera and radio network deployed over a significant fraction of western Europe and a small fraction of Canada. As of today, it consists of 150 cameras and 25 European radio receivers and covers an area of about 1.5 106 km2.

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Methods. The FRIPON network, fully operational since 2018, has been monitoring meteoroid entries since 2016, thereby allowing the characterization of their dynamical and physical properties. In addition, the level of automation of the network makes it possible to trigger a meteorite recovery campaign only a few hours after it reaches the surface of the Earth. Recovery campaigns are only organized for meteorites with final masses estimated of at least 500 g, which is about one event per year in France. No recovery campaign is organized in the case of smaller final masses on the order of 50 to 100 g, which happens about three times a year; instead, the information is delivered to the local media so that it can reach the inhabitants living in the vicinity of the fall.

Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License ( ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

However, we are not very efficient at recovering the meteorites that hit the Earth. Estimates based on previous surveys (Bland et al. 1996) and on collected falls [Meteoritical Bulletin database1 ] indicate that, for meteorites with masses greater than 100 g, probably less than 1 in 500 that fall on Earth are currently recovered. In addition, taking France as an example, recovery rates were significantly higher in the nineteenth century than they are now: 45 meteorites were observed to fall and found on the ground in the nineteenth century, whereas they were 5 times fewer in the twentieth century (Fig. 1), showing that there is at present a large potential for improvement. Hot and cold deserts are privileged dense collection areas, but most meteorites are found hundreds and up to millions of years after their fall (Hutzler et al. 2016; Drouard et al. 2019). They have thus been exposed to terrestrial alteration, which has partly obliterated the scientific information they contain. Also, the critical information regarding their pre-atmospheric orbit is no longer available.

Records of incoming meteorites started with the appearance of photographic plates at the end of the twentieth century. A first attempt to observe incoming bolides was made in the United States and consisted of a small camera network that was operated between 1936 and 1951 (Whipple 1938), but it was only in the middle of the twentieth century that the first fireball observation networks were developed with the aim of recovering meteorites. Two such networks were established in the 1960s. The first was the Prairie Network (McCrosky & Boeschenstein 1965) in the center of the United States, which remained operational from 1964 to 1975. This network comprised 16 stations located 250 km apart. Only one meteorite was recovered thanks to this network (Lost City, 1970; McCrosky et al. 1971). The low efficiency of the Prairie Network, despite the large area it covered (750 000 km2) mainly resulted from the low efficiency of the photographic plates, the large distance between the stations, and the slow pace of the data reduction process.

The European Fireball Network (EFN) was also developed in the 1960s, under the guidance of the Ondrejov Observatory, following the recovery of the Přbram meteorite in 1959 (Ceplecha 1960). It is still active, currently covers 1 106 km2 with about 40 cameras, (Oberst et al. 1998) and benefits from modern equipment. So far, this network has enabled the recovery of nine meteorites (Table 1).

In 1971, the Meteorite Observation and Recovery Project (MORP) project was established over part of Canada and led to the recovery of the Innisfree meteorite (Halliday et al. 1978). The modern digital camera extension of this network, called the Southern Ontario Meteor Network, led to the recovery of the Grimsby meteorite (Brown et al. 2011). The MORP project comprises 16 cameras and covers a surface area of 700 000 km2. Other networks using photographic techniques have also been developed, such as the Tajikistan Fireball Network (Kokhirova et al. 2015), which consists of 5 cameras and covers 11 000 km2. However, none of these other networks have made it possible to recover meteorites so far. We note the existence of other networks such as the SPMN network, which facilitated the recovery of the Villalbeto de la Pea (Trigo-Rodrguez et al. 2006) and Puerto Lpice (Llorca et al. 2009) meteorites, as well as the Finnish Fireball Network, which facilitated recovering the Annama meteorite (Gritsevich et al. 2014; Trigo-Rodrguez et al. 2015). Last, the Desert Fireball Network (Bland et al. 2012) was implemented in Australia in 2007. This network is based on high-resolution digital cameras and has made it possible to recover four meteorites: Bunburra Rockhole in 2007 (Spurn et al. 2012), Mason Gully in 2010 (Dyl et al. 2016), Murrili in 2015 (Bland et al. 2016), and Dingle Dell in 2016 (Devillepoix et al. 2018). The success of this network results from the efficiency of the cameras and the size of the network as well as an efficient data reduction and analysis process (Sansom et al. 2019a). A method to construct a successful fireball network is discussed in Howie et al. (2017).

As of today, there are 38 meteorites with reliable reconstructed orbits, 22 of which were detected by camera networks (see Table 1). Among the remaining 16 meteorites, 14 are the result of random visual observations such as the Chelyabinsk event (data from security cameras were used for orbit computation; Borovička et al. 2013a) and two meteorites were detected as asteroids before their fall (Almahata Sitta and 2018LA). During the same time interval (1959-2020), 397 meteorites were recovered after their falls were witnessed by eye (Meteoritical Bulletin Database).

The Fireball Recovery and InterPlanetary Observation Network (FRIPON) scientific project was designed to contribute to this global effort to recover fresh meteorites. It comprises a network deployed over a large fraction of western Europe and a small fraction of Canada (seeFig. 2). As of today, this network consists of 150 cameras and 25 receivers for radio detection and covers an area of 1.5 106 km2 (Sect. 2). The FRIPON network is coupled in France with the Vigie-Ciel citizen science program, the aim of which is to involve the general public in the search for meteorites in order to improve their recovery rate. In the present paper, we first describe the technology of the FRIPON network and its architecture, and finally we give the first results obtained after four years of observations and report on the first meteorite recovery in Italy2 (Gardiol et al. 2020).

Distribution of observed meteorite falls in France. In nineteenth century France, 45 meteorites were recovered after their fall was observed, a number that fell by a factor of 5 in the twentieth century. Even in the nineteenth century, witnessed falls were not randomly distributed. They were mostly located in the great river plains (Seine and Loire in the northwest, Garonne in the southwest, and Rhne valley in the southeast). In these regions, the population was denser, the view is free of obstacles (such as mountains), and the skies are often clear. The striking difference between the two centuries illustrates the need for distributed observers for meteorite recovery. Rural populations have declined because of urbanization in the twentieth century. A camera network such as FRIPON can monitor atmospheric entries and take over that role that was previously played by human observers. However, trained human eyes are still required to recover the meteorites; this is the aim of the Vigie-Ciel citizen science program (Colas et al. 2015).

The FRIPON science project regroups all the above-mentioned national networks, with all the cameras monitored and remotely controlled by the Service Informatique Pythas (SIP; Aix-Marseille University, France), which maintains the whole network with the support of the scientific team. All the data from the FRIPON network are stored and processed in Marseille. The data processing consists of monthly astrometric and photometric reduction of the calibration images and daily processing of multi-detections. Two databases host the data. One stores the raw data and the other stores higher-level, processed data, such as orbits and trajectories. These data are available to all coinvestigators of the network4. On request, national data can be sent to a different reduction pipeline for alternate processing and storage5.

Since the early 2000s, digital cameras have been used by all networks that are deployed to monitor fireballs. Two alternate technical solutions are adopted. The first is based on a low-resolution detector (e.g., Southern Ontario Meteor Network; Brown et al. 2011), while the second relies on a high-resolution detector (e.g., Desert Fireball Network; Bland et al. 2012). The measurements acquired by low-resolution cameras can be accurate enough to compute orbits and strewn fields as long as the network is dense, with numerous cameras. For example, the Southern Ontario Meteor Network, which has been operating in Canada since 2004, led to the recovery of the Grimsby meteorite (Brown et al. 2011). In the case of the FRIPON network, we followed the philosophy of the Canadian Fireball Network (Brown et al. 2011) as detailed hereafter.

The optical device and the CCD were embedded into a special case (Fig. 3) sealed with a transparent dome, thereby allowing us to record full-sky images. Moreover, these cases are equipped with a passive radiator, which serves to release the heat produced by the electronics during the warm periods of the year to minimize CCD dark current.