More than 10^7 kg of extraterrestrial objects or meteoroids ranging in size from a few microns to tens of meters in diameter enter the Earth’s atmosphere every year. A small fraction of these yields free samples of extraterrestrial matter - meteorites - for laboratory study. The majority, which burn up or ablate completely in the Earth’s atmosphere, appear as visible meteors in the night sky. Recording meteor activity and modelling the process of ablation allow us to measure directly the flux of small planetary impactors. This provides the 'ground truth' for estimating present cratering rates and planetary surface ages by implication.
The application of the latest observational and modeling techniques has rendered meteor science as one of the leading avenues for investigating the nature and origin of interplanetary matter and its parent bodies. This session will provide a forum for presenting fundamental results and novel ideas in this area and informing the broader planetary science community of the interdisciplinary impact of present and future work.
We are sorry, but presentations are only available for users who registered for the conference. Thank you.
Oral and Poster presentations and abstracts
The Desert Fireball Network is a fireball observing network which stretches across the southern part of the Australian continent. To date, it has over 50 cameras, covering an area of approximately 2.5m km2. Its purpose is to observe and triangulate fireballs, calculate trajectories for incoming meteorites. The camera network has been operational in digital form since 2012, and to date as captured approximately 1.5PTB of data, primarily all sky images. We present an overview of the DFN results to date, detailing the dataset of approximately 1500 orbits, and over 30 possible candidate meteorite falls, and describe the most recent results. In particular, the team have recently recovered two candidate meteorites; one from the Nullarbor and one from the Simpson Desert in South Australia. The comparison the stories of these recoveries illustrate the typical issues of searching meteorite searching, and of verifying the meteorite’s provenance, and possible origin of the rocks is interesting to compare.
How to cite: Towner, M., Sansom, E., Cupak, M., Devillepoix, H., Anderson, S., Shober, P., Howie, R., Hartig, B., and Bland, P.: The Australian Desert Fireball Network: overview and recent results, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-167, https://doi.org/10.5194/epsc2021-167, 2021.
In Spain, the Spanish Meteor Network (SPMN) has been operating for 25 years, recording meteoric events and re-entries over the Iberian Peninsula, Morocco, and the insular territory . This is a pro-am project involving a scientific team specialized in areas such as astronomy, geology, geophysics, and chemistry.
Obtaining the trajectory of meteoroids impacting the atmosphere is crucial both for the recovery of possible meteorites and for studying their origin in the Solar System. Some of these objects can be dynamically associated with their parent bodies, being part of meteoroid streams . Herein lies the importance of monitoring the sky constantly and completely from multiple monitoring stations. The SPMN network has 34 stations equipped with all-sky cameras or wide-angle lenses, and we recently upgraded the software to reduce the ever-increasing amount of data. Here we present our automated Python (called 3D-FireTOC) pipeline for meteor detection from digital systems, astrometric measurements, photometry, atmospheric trajectory reconstruction and heliocentric orbit computation, all in all quantifying the error measurements in each step .
- Analytical procedures of the 3D-FireTOC software
A key step to achieve proper reduction is the development of automated astrometry to ensure the measurement of meteors appearing in the field of view of video-detection systems. To do this, we use computer vision techniques to obtain the pixel coordinates corresponding to the moving meteor in each frame. Each image is processed and compared with a reference image (without detection) allowing us to extract the pixels that have been activated by the meteor. In this way, the centroid of the detected pixel area corresponds to the position in the image of the meteoroid (see Figure 1).
Due to the changing nature of this type of recordings as well as possible light reflections and obstacles in the field of view, we have implemented three methods to avoid false positives: 1) discriminating by the size of the detected area excluding excessively small and large contours, 2) predicting the next position of the meteor with a Kalman filter, and 3) post-processing the detected points and applying clustering algorithms to check if the trajectory is consistent with a more or less straight line. Figure 2 shows an example of false positive avoidance.
To transform the pixels into real coordinates is necessary to identify stars in the image to obtain their position in the sky for the date of the event. To do this, we use corner detection algorithms since the stars appear randomly distributed in the sky and far from each other. Again, we use clustering algorithms but this time selecting the points identified as noise, as can be seen in Figure 2.
Once the stars have been identified, thanks to JPL's Horizons ephemerides, we can model the deformation produced by the lens by finding the correspondence between pixel and real position. In particular, we apply a polynomial variant  of the method proposed by  for all-sky camera astrometry.
The result we obtain from each observation is an apparent trajectory projected on the celestial sphere. Naturally, two or more observations sufficiently far apart are required to triangulate the real position of the meteoroid. Because these fragments reach the Earth at very high velocities, air resistance practically does not bend their trajectories so that they can approximate a straight line. This allows the plane intersection method to be applied to reconstruct the atmospheric flight . Finally, the trajectory is projected backwards to obtain the radiant, i.e. the position of origin in the sky. From the atmospheric flight, the α-β criterion can be applied approximating the chances that the event produced meteorites [7,8].
- Recent example: SPM010521 event
On May 1, 2021, a bolide flew over Aragón reaching a magnitude of -11. It was recorded by 6 stations of the SPMN network (Table 1 and Figure 3). The luminous phase started at 107 km altitude and ended at 43 km. The flight angle with respect to the horizontal was 24º degrees. With a geocentric velocity of 30 km/s, its orbital parameters indicate a possible association with a IAU working list of meteor showers called Southern May Ophiuchids. Unfortunately, it was not a meteorite-dropper event as reveals the α-β criterion result: α=315.4, β=1.2, an estimated initial mass of 0.1 kg and an estimated final mass less than one gram. Figure 4 shows the 3D representation and scale of the reconstructed atmospheric trajectory, as well as the calculated heliocentric orbit.
With the implementation of this new software, the SPMN increases its capacity to rapidly generate new knowledge about the origin of large meteoroids, and their capacity to generate hazard. Multi-station analyses also provide valuable information about their bulk physical properties and, from their heliocentric orbits, the dynamic association with comets, asteroids, or even planetary bodies can be inferred . In addition, the automation of the meteor detection and the entire analysis process allows immediate preparation of meteorite search campaigns. Our software developments will be soon applied to increase our close cooperation with FRIPON .
As an example of application, we present the results obtained on SPMN010521, a recent fireball recorded and analyzed by the SPMN, which did not produce meteorites and seems to be dynamically associated with an unestablished meteor shower.
This research has been funded by the research project PGC2018-097374-B-I00, (MCI-AEI-FEDER, UE). Funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme for the project “Quantum Chemistry on Interstellar Grains” (QUANTUMGRAIN, grant agreement No. 865657) is acknowledged.
-  Trigo-Rodríguez J.M. et al. (2006) Astronomy & Geophysics 47, 6.26
-  Hughes, D. W.(1990) MNRAS 245, 198-203.
-  Peña-Asensio, E., Trigo-Rodríguez, J. M., Gritsevich, M., & Rimola, A. (2021) MNRAS 504(4), 4829-4840.
-  Bannister, S. M., Boucheron, L. E., & Voelz, D. G. (2013) ASP125(931), 1108.
-  Borovička, J. (1992) AICAS, 79.
-  Ceplecha, Z. (1987) BAIC, 38, 222-234.
-  Gritsevich M., 2009, Advances in Space Research, 44, 323.
-  Sansom E. K., et al., 2019, The Astrophysical Journal, 885, 115.
-  Colas, F. et al. (2020) Astronomy & Astrophysics 644, id.A53, 23 pp.
How to cite: Peña-Asensio, E., Trigo-Rodríguez, J. M., Gritsevich, M., Rimola, A., Izquierdo, J., Zamorana, J., Chioare-Díaz, M., Iglesias-Marzoa, R., Milian Biel, J., Ibañez, V., Robles, A. J., Pastor, S., de los Reyes, J. A., Guasch, C., Aznar Carbó, M., and Lasala, A.: New SPMN network software for fireball detection and analysis: the SPMN010521 bolide event, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-738, https://doi.org/10.5194/epsc2021-738, 2021.
On February 28, 2020 at 09:30:32 UTC, a daytime superbolide was observed over southeastern Slovenia and neighbouring countries1. In the following days, three meteorite pieces (469, 203, and 48 grams)2 were recovered nearby the Slovenian city of Novo Mesto by local people. The meteorite was classified as an L5 ordinary chondrite, more or less brecciated and shocked.
In this work we reconstruct the trajectory using the available video data which consist of two static security cameras and four dash cameras mounted on cars in motion (Figure 1). We use a new radial distortion method developed by Vida et al. (2021) to accurately model the lens distortion of individual cameras and we determine the position of the vehicles to a precision of several centimetres on every video frame.
Figure 1. Map of observer locations and the fireball trajectory (red line).
The preliminary trajectory was computed using the lines of sight method and the trajectory uncertainties were computed using the Monte Carlo method (Vida et al., 2020) by adding 3σ noise to the original measurements. The fireball was first observed at a height of 68.7 km and it reached an end height of 17.1 km. The fireball had an entry angle of 47.812° ± 0.096° and an initial velocity of 22.098 ± 0.012 km/s (computed using measurements above 45 km, i.e. before any noticeable deceleration was visible). Figure 2 shows that the average per-station trajectory spatial fit errors were around 100 m (200 m maximum). More observations will be included in a future analysis.
Figure 2. Spatial trajectory fit residuals. The Tkon and Senj stations were fixed security cameras, but only Tkon was calibrated on stars.
The fireball had the following geocentric radiant (J2000):
330.920 ± 0.095 deg
+2.320 ± 0.098 deg
18.991 ± 0.014 km/s
333.802 ± 0.093 deg
+13.319 ± 0.103 deg
The computed orbit is:
0.5679 ± 0.0011 AU
1.451 ± 0.004 AU
0.60866 ± 0.0006
8.755 ± 0.063 deg
82.649 ± 0.184 deg
1.7473 ± 0.0072 years
4.4156 ± 0.0091
A parent body search returned a match for a few objects, depending on the used D criterion. The Potentially Hazardous Asteroid 2005 OX had the Southworth & Hawkins (1963) DSH criterion value of 0.078, while the Drummond (1981) criterion had close matched for asteroids 2008 DK5 (DD = 0.043), 2004 DF2 (DD = 0.050), and also 2005 OX (DD = 0.058). Possible connection to these objects may be a topic of future work, although these correlations might be spurious as the orbital parameter space is dense in that region.
The fireball was bright enough to be picked up by the US government sensors3 which measured a total radiated energy of 11.5×1010 J. Assuming a typical L chondrite bulk density of 3620 kg/m3, we estimate that the meteoroid had an initial mass of 470 kg, corresponding to a diameter of about 0.63 m. We use the energy estimate to scale the observed light curve using the luminous efficiency of Borovička et al. (2020) – it compares well to an empirically derived light curve using a light source of known magnitude (reflection of the Sun from a chromium sphere at various distances). The fireball had one major fragmentation event at the height of 35 km which was picked up by the seismographs in the vicinity.
A total of 18 fragments were tracked on the videos after the main fragmentation. The dynamic mass analysis shows that the final mass of the largest fragment was on the order of 10 kg. This rather large fragment has not been found yet – it is possibly buried into the soft ground and ploughed over. The fireball experienced fragmentations at dynamic pressures of 2.5, 3.5, and 10 Mpa, as shown in Figure 3. The peak dynamic pressure is the highest ever measured, after the the Benešov fall (Borovička et al., 1998).
Figure 3. Left: Light curve measured on the Sesvete dash cam video. Blue curve is scaled using the CNEOS energy, and the orange curve was derived using the chromium sphere and the original dash camera. Middle: Velocity measurements and the Gritsevich (2007) model fit. Right: Dynamic pressures derived using the velocity fit and the NRL-MSISE00 air density model (Picone et al., 2002). Observed fragmentation points are marked with horizontal lines.
The distribution of finds on the ground indicate that these meteorites were not produced at the end height but that some were ejected at several discrete heights above 20 km.
1AMS fireball report: https://fireball.imo.net/members/imo_view/event/2020/1027
2Meteoritical Bulletin Database, entry for Novo Mesto: https://www.lpi.usra.edu/meteor/metbull.php?code=72430
3CNEOS Fireballs: https://cneos.jpl.nasa.gov/fireballs/
Borovička et al. (1998). A&A, 334, 713-728.
Borovička et al. (2020). AJ, 160(1), 42.
Drummond, J. D. (1981). Icarus, 45(3), 545-553.
Gritsevich, M. I. (2007). Solar System Research, 41(6), 509-514.
Picone et al. (2002). Journal of Geophysical Research: Space Physics, 107(A12), SIA-15.
Southworth, R. B., & Hawkins, G. S. (1963). Smithsonian Contributions to Astrophysics, 7, 261-285.
Vida et al. (2020). MNRAS, 491(2), 2688-2705.
Vida et al. (2021). The Global Meteor Network - Methodology and First Results. Submitted to MNRAS.
How to cite: Vida, D., Šegon, D., Šegon, M., Atanackov, J., Ambrožič, B., McFadden, L., Ferrière, L., Kac, J., Kladnik, G., Živčić, M., Merlak, A., Skokić, I., Pavletić, L., Vinčić, G., Ćiković, I., Perkó, Z., Ilari, M., Malarić, M., and Macuka, I.: Novo Mesto meteorite fall – trajectory, orbit, and fragmentation analysis from optical observations, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-139, https://doi.org/10.5194/epsc2021-139, 2021.
Meteors and fireballs, often as part of meteor showers, are commonly observed in the atmosphere of Earth. The same phenomena is expected to take place in other planets (Christou, 2005). Observations are rare, as no suitable instruments have been launched in interplanetary missions, however, these observations can push forward our understanding of interplanetary dust (Christou et al., 2019). In recent years, a number of impacts on Jupiter have been reported based on ground based amateur observations (Hueso et al., 2018) and Juno observations (Giles et al., 2021). On Mars, the Panoramic Camera on Mars Exploration Rover Spirit tried to observe meteors, with no conclusive detections (Domokos et al., 2007), however a meteor was possibly imaged by a navigation camera (Selsis et al., 2005).
The Visual Monitoring Camera (VMC) onboard Mars Express is a wide field camera initially designed as an engineering camera (Ormston et al., 2011). VMC was recently upgraded to a science instrument, and in recent years different works have shown the scientific capabilities of this camera (e.g. Sánchez-Lavega 2018; Hernández-Bernal et al., 2021a;2021b).
As part of the VMC science program, we performed a few campaigns to try to find meteors or fireballs. To maximize probabilities, we programmed observations coincident with theoretically predicted meteor showers on Mars. While the sensibility of the VMC sensor is low, which reduces the probability to find meteors, its field of view is very wide compared to other instruments, which enhances the probabilities. So far, we have not captured any clear meteor or fireball.
We planned our campaigns based on predictions published by Christou (2010). Hardware limitations require all other instruments to be switched off when VMC is observing, this is an important limitation to this work, as only a few observations could be performed, and VMC observations cannot be very long. VMC accepts exposures of up to ~90 s, however observations longer than ~30 s are highly affected by the thermal noise of the sensor, additionally there is a gap of around 48 s between VMC images. As a result, less than 40% of the time VMC is switched on can be effectively used for monitoring.
Exposures of a few seconds by VMC are usually noisy, and they require processing to extract the presence of dim objects, such as stars, planets (e.g. https://twitter.com/esaoperations/status/1247096203550101504), or in this case, meteors. In the case of meteors, we expect them to appear as dim lines in only one image, then the best way to extract the noise from an image is by making a synthetic dark from images obtained close in time. Considering the sensibility of VMC as revealed by observations of stars, we expect it to be able to capture only very bright meteors, around absolute magnitudes of -6 to -10. Figure 1 shows an example of the simulations performed to analyze observability.
We performed two campaigns to try to find meteors or fireballs, table 1 summarizes these campaigns.
|Parent Comet||Ls||Velocity||SZA||Observations||Accumulated time|
|5335 Damocles||47.8||29.9 km/s||98.4º||2019-07-03_23.54-01.13||25 minutes|
|1P Halley||325.9||53.8 km/s||121.4º||
Table 1. Meteor shower details from Table 2 in Christou (2010).
Once processed, images did not show any significant trace potentially related to a meteor burning in the atmosphere. The total effective observation time was 46 minutes, part of this time elapsed out of the expected area for the meteor shower.
Figure 2. Scheme of an observation. The area expected for the meteor shower is green shaded. Dark shaded area is the night.
We did not achieve positive results. The main reason is probably the low sensibility of the VMC sensor. While VMC is a low quality engineering camera designed in the 90s, modern commercial cameras can achieve very high sensibilities. The technical planning of these campaigns shows that VMC-like cameras could be a tool suitable to monitor meteor activity on Mars and other planets from space in the future, as already pointed by Christou et al. (2012). The wide field of view of VMC, when exploited from a moderate distance to the planet, provides full-disk images covering wide areas, and thus potentially enabling the large-scale monitoring of meteor activity.
Christou, A. A., "Predicting Martian and Venusian meteor shower activity." Modern Meteor Science An Interdisciplinary View. Springer, Dordrecht, 2005. 425-431.
Christou, A. A., "Annual meteor showers at Venus and Mars: lessons from the Earth." Monthly Notices of the Royal Astronomical Society 402 (2010): 2759-2770.
Christou, A. A., et al. "Orbital observations of meteors in the Martian atmosphere using the SPOSH camera." Planetary and Space Science 60 (2012): 229-235.
Christou, A. A., et al. "Extra-terrestrial meteors." (2020). Chapter 5 in “Meteoroids: Sources of Meteors on Earth and Beyond”, Cambridge University Press (2019)
Domokos, Andrea, et al. "Measurement of the meteoroid flux at Mars." Icarus 191 (2007): 141-150.
Hernández‐Bernal, J., et al. "An extremely elongated cloud over Arsia Mons volcano on Mars: I. Life cycle." Journal of Geophysical Research: Planets 126 (2021a): e2020JE006517.
Hernández‐Bernal, J., et al. "A Long‐Term Study of Mars Mesospheric Clouds Seen at Twilight Based on Mars Express VMC Images." Geophysical Research Letters 48 (2021b): e2020GL092188.
Giles et al. “Detection of a bolide in Jupiter’s atmosphere with Juno UVS”. Geophysical Research Letters, 48 (2021).
Hueso, Ricardo, et al. "Small impacts on the giant planet Jupiter." Astronomy & Astrophysics 617 (2018): A68.
Ormston, T., et al. "An ordinary camera in an extraordinary location: Outreach with the Mars Webcam." Acta Astronautica 69.7-8 (2011): 703-713.
Sánchez-Lavega, A., et al. "Limb clouds and dust on Mars from images obtained by the Visual Monitoring Camera (VMC) onboard Mars Express." Icarus 299 (2018): 194-205.
Selsis, Franck, et al. "A martian meteor and its parent comet." Nature 435.7042 (2005): 581-581.
How to cite: Hernández-Bernal, J., Sánchez-Lavega, A., Del Río-Gaztelurrutia, T., Hueso, R., Cardesín-Moinelo, A., Marín-Yaseli de la Parra, J., Merrit, D., Wood, S., Martin, P., and Titov, D.: Looking for Meteors and Fireballs in the atmosphere of Mars from the Visual Monitoring Camera (VMC) on Mars Express, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-515, https://doi.org/10.5194/epsc2021-515, 2021.
During its first six months of operations onboard the Zvezda module of the International Space Station, the Mini-EUSO wide-field telescope detected more than two thousand meteors in approximately 40 hours of data taking. Mini-EUSO observes the Earth’s atmosphere in the UV range (290 – 430 nm) with a field of view of about 44° x 44° through a nadir-facing, UV-transparent window with a focal surface of 48 x 48 pixels and a resolution of about 6.3 km on ground. While temporal resolution and triggering are at the timescales of 2.5 μs to potentially record UHECR showers and TLEs, Mini-EUSO performs a continuous monitoring of the UV emission at a 40.96 ms timescale, where meteors are recorded. We developed an analysis pipeline able to offline detect, track and characterize meteor events and subsequently compute their physical parameters, such as tangential speed, magnitude, duration and trajectory azimuth. In this contribution, we present the implemented reduction methods and the results of the analysis of the sample, providing comparisons with existing databases of meteors observed in the optical band.
How to cite: Barghini, D., Battisti, M., Belov, A., Bertaina, M. E., Bertone, S., Bisconti, F., Capel, F., Casolino, M., Cellino, A., Ebisuzaki, T., Gardiol, D., Klimov, P., Marcelli, L., Miyamoto, H., Picozza, P., Piotrowski, L. W., Prévot, G., Reali, E., Sakaki, N., and Takizawa, Y. and the Mini-EUSO collaboration: Analysis of meteors observed in the UV by the Mini-EUSO telescope onboard the International Space Station, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-243, https://doi.org/10.5194/epsc2021-243, 2021.