January 6, 2020 No By Asma STEINHAUSSER - Translated by Jim Rowe
A first meteorite for the FRIPON-Vigie-Ciel network! It was found in Italy using cameras of the Italian fireball network PRISMA which is part of the European e-FRIPON network, as is SCAMP in the UK or MOROI in Romania.
In collaboration with the PRISMA team, a meteorite drop zone was calculated following the detection of a fireball/bolide on January 1 at 18:26:54 UT (Figure 1). After an appeal to the Italian population, two fragments with a total mass of 55 g (Figure 2) were found by a resident near Cavezzo, near the calculated fall zone.
Figure 1: The bolide of 01 January 2020, 18:26:54 UT, filmed with the FRIPON/PRISMA camera at Loiano (Italy). Credit: Fripon/Vigie-Ciel
Figure 2: The two fragments found following the appeal to the local population. The appearance is characteristic of a fresh meteorite, with a beautiful black fusion crust on the outside. Credit: INAF Media
About 50 witnesses filled out the online fireball reporting form made available by the American Meteor Society and its partners: the International Meteor Organization and PRISMA (Italy). These reports led to the determination of an initial estimate of the bolide’s trajectory that indicated a possible fall in the vicinity of the town of Cavezzo in the province of Modena (Figure 3). Unfortunately, at this time the form did not allow video recordings of the bolide to be obtained, which is different from what happens routinely with meteorite falls in the United States. It should be noted that the trajectory obtained by the FRIPON/PRISMA network confirmed (and refined) that obtained from the witnesses. The data from the FRIPON-PRISMA cameras was also used to calculate the orbit and the likely drop zone of the objects.
Figure 3: AMS/IMO/PRISMA visual observation map and estimated meteoroid trajectory
The FRIPON network continuously records the brightest bolides, allowing alerts to be issued when an event occurs. It is coupled with a program to calculate trajectories and orbits to understand the origin and fate of these objects that enter our atmosphere. The network of cameras has spread over several countries. So, other networks have been organised in other countries such as the SCAMP network in the UK & Ireland or the Prisma network in Italy. The data acquired by the combination of these networks is managed by the OSU Pytheas at the University of Aix Marseille. It is then analysed by researchers from the various institutes involved in the FRIPON project, principally the Paris Observatory. A thesis will be presented in March 2020 by a doctoral student (Simon Jeanne) on this subject. Data collected by the PRISMA network as well as all cross-border detections carried out in Italy and France are also stored and processed at the INAF site in Trieste.
It was the Prisma network that detected the bolide on January 1st. Eight cameras recorded the phenomenon (Figure 4) including that of Loiano (Figure 1).
Figure 4: MAP of the cameras of the FRIPON/PRISMA network that recorded the phenomenon (those which detected it are shown in green)
In addition to video cameras, the observer network uses radio receivers to track bolides. The spectrogram below represents the successive radio echoes received from the GRAVES military radar (located near Dijon) on the high-temperature plasma surrounding the object and then on the ionised track remaining in the atmosphere.
Figure 5: Radio detection of the bolide from 1 January 2020 by the radio station FRIPON de Zicavo in Corsica. The horizontal axis of the figure represents the time that elapses, and the vertical axis corresponds to the frequencies received. The frequency decreases rapidly (like the siren of an ambulance passing at high speed), due to the Doppler-Fizeau effect affecting the received signal. Credit: FRIPON/Vigie-Col
The camera recordings were used to determine the physical parameters of the object. The calculations made following this detection by the FRIPON/PRISMA network told us the orbit of this object (Figure 6), its trajectory (Figure 7) and the area of meteorite fall.
Figure 6: Orbit of the meteoroid that caused the January 1, 2020 meteorite before its atmospheric entry. The aphelia of this orbit (the furthest point from the Sun), at just over two astronomical units, is in the inner asteroid belt from which the object originates. Credit: FRIPON/Vigie-Heaven/Simon Jeanne
Figure 7: Atmospheric trajectory of the 1 January 2020 bolide calculated from video recordings of the FRIPON/PRISMA network cameras. Credit: FRIPON/Vigie-Ciel
Prior to its atmospheric entry, the meteoroid originally in the bolide had a mass of about 8 kg and entered the atmosphere with a speed of about 12 km/s (the lowest ever recorded by FRIPON - Figure 8) and a fairly significant tilt of 68 degrees relative to the horizontal, so the ablation was strong despite the low speed of the object.
The calculated total final mass of the object was 150 g. However, a burst of light (Figure 9) was recorded at an altitude of 32 km corresponding to fragmentation. It was thus inferred that smaller or equal pieces of the 150g were generated and dispersed in an elliptical strewn field, with the most massive objects travelling the greatest distance.
The final fireball altitude of 20 km (Figure 10) and the steep inclination made it possible to calculate the trajectory fairly accurately during the dark flight part (below 20 km) taking into account the winds. This data is then used to determine the drop zone of the objects.
Figure 8: Graph representing the velocity of the meteoroid according to altitude during its atmospheric re-entry: the initial velocity of the object was 12 km/s. Credit: FRIPON/Vigie-Ciel/Simon Jeanne Figure 10: Chart showing the altitude of the meteoroid according to time; the bolide became bright at about 75 km above sea level, and went off more than 6 seconds later, when it was less than 20 km above the ground. This graph allows us to say that there have been one or more objects that have been able to survive. Credit: FRIPON/Vigie
Figure 9: Graph representing the brightness of the bolide according to altitude: A burst of light probably due to fragmentation was recorded at an altitude of 35 km. The burst of light of magnitude -10 was 10,000 times brighter than the star Vega, the brightest star in the northern hemisphere. Credit: FRIPON/Vigie-Ciel/Simon Jeanne.
Figure 10: Graph representing the altitude of the fireball (or bolide) as a function of time; the fireball became bright at an altitude of around 75 km, and continued for more than 6 seconds until it was less than 20 km above the ground. This graph allows us to say that there were one or more objects that survived. Credit: FRIPON / Vigie
A first article was published on January 1st on the Website of the Prisma network to describe the event. An appeal to the public was launched on 2 January. An excerpt - “the fall zone is around the village of Disvetro ,a few kilometres northwest of Cavezzo (Modena), in the middle of the Po valley. The area of uncertainty at 2 sigmas is about 2.2 long and 1.5 km wide. Given the fragmentation processes to which the meteoroid has been subjected, some fragments may have landed at the junction between Rovereto sul Secchia and Disvetro.” The inhabitants of these cities were therefore invited to search for the meteorites around their homes.
The article then published on January 4 on the website of the Prisma network tells that the call was heard. Indeed, a resident of the area reported having discovered two meteorite fragments of 55 g in total in the province of Modena on the edge of the estimated drop zone. A video was also shot and published on the channel of the Institute of Astrophysics in Turin.
In this article, Daniele Gardiol of the Institute of Astrophysics in Turin, who coordinates the Prisma national network, welcomes this find. It is the result of many years of international and European work and collaboration between several scientific research and mediation structures and the general public.
On the French side, the project managers FRIPON/Vigie-Ciel (François Colas, IMCCE, Observatory of Paris; Brigitte Zanda, MNHN; Sylvain Bouley, GEOPS, Université Paris Saclay) are very enthusiastic about these early discoveries and recall that these research and participatory science projects also aim to raise public awareness about the scientific importance of meteorites, to ensure that they are no longer lost after their falls and that they are analysed by specialists and preserved for everyone’s benefit. This is what is happening in Italy right now, the collaboration between amateurs and researchers promises great discoveries!
If you see a bolide in the sky, report it on: sky watch.imo.nand
To follow the news of the FRIPON/Vigie-Ciel project and to be contacted in case of training or fall in the region, register here
If you want to participate in the search for impact craters, log on to: vigie-cratere.org
a bolide or fireball is a very bright meteor (synonymous shooting star). A bolide is generally referred to as any meteor brighter than the planet Venus (the brightest object in the sky after the Sun and Moon)
a meteor (or shooting star) is the light line observed when interplanetary dust or a small meteoroid enters the Earth’s atmosphere at very high speeds (between 12 and 72 km/s)
a meteoroid is a small particle generally from a few millimetres to a few tens of centimetres in diameter that moves through space. This creates a meteor if it enters Earth’s atmosphere. If the meteoroid is sufficiently massive, part of the object can withstand this entry into the atmosphere, and this is called a meteorite.
a meteorite is the stony or metal rock that is found on earth, when part of a sufficiently massive meteoroid has managed to pass through the atmosphere and reach the ground.