114 research outputs found
Measuring the Terminal Heights of Bolides to Understand the Atmospheric Flight of Large Asteroidal Fragments
No full textThe extent of penetration into the Earth's atmosphere of a meteoroid is defined by the point where its kinetic energy is no longer sufficient to produce luminosity. For most of the cases this is the point where the meteoroid disintegrates in the atmosphere due to ablation process and dynamic pressure during flight. However, some of these bodies have particular physical properties (bigger size, higher bulk strength, etc.) or favorable flight conditions (lower entry velocity or/and a convenient trajectory slope, etc.) that allow them to become a meteorite-dropper and reach the ground. In both cases, we define the end of the luminous path of the trajectory as the terminal height or end height. Thus, the end point shows the amount of deceleration till the final braking. We thus assume that the ability of a fireball to produce meteorites is directly related to its terminal height. Previous studies have discussed the likely relationship between fireball atmospheric flight properties and the terminal height. Most of these studies require the knowledge of a set of properties and physical variables which cannot be determined with sufficient accuracy from ground-based observations. The recently validated dimensionless methodology offers a new approach to this problem. All the unknowns can be reduced to only two parameters which are easily derived from observations. Despite the calculation of the analytic solution of the equations of motion is not trivial, some simplifications are admitted. Here, we describe the best performance range and the errors associated with these simplifications. We discuss how terminal heights depend on two or three variables that are easily retrieved from the recordings, provided at least three trajectory (h, v) points. Additionally, we review the importance of terminal heights, and the way they have been estimated in previous studies. Finally we discuss a new approach for calculating terminal heights.Peer reviewe
Instructions for Ongoing Observations of the Dust Trail from the 2007 Outburst of Comet 17P/Holmes
No full textThese instructions provide guidance for the continuous observation of the dust trail resulting from the 2007 outburst of Comet 17P/Holmes.
1. Software and Access
To facilitate data collection and analysis the software is open-access.
2. Coordinate Data
The attached coordinate lists contain calculated coordinates for the dust trail of Comet 17P/Holmes. These coordinates are based on predictions for the behavior of the dust trail near the comet's 2007 outburst point (referred to as the northern node) and also at the southern node. The calculations were conducted according to the methodology detailed in Gritsevich et al. 2022.
3. Coordinate List Columns
The coordinate list includes the following columns:
Observatory name
Particle position in the narrowest part of the trail
JPL date-time
Julian Date (JD)
Right Ascension (RA) and Declination (DEC) in decimal notation
RA and DEC in normal notation
Altitude from the horizon
Azimuth
Distance to the trail from Earth in Astronomical Units (AU)
These coordinates are initially calculated for observatories in Kouvola, Utah, and Siding Spring, but they are adaptable for use with telescopes at any location on Earth.
4. Observation Period
The dust trail is expected to be observable using ground-based telescopes from September 2023 to March 2025, both at the northern and southern nodes.
5. Python Code
An attached Python code provides 3D positions of the dust trail. This code can be utilized with both ground-based and space-based telescopes. The Python program employs the Skyfield library and takes into account the topographical location of Earth, correcting for light time and atmospheric refraction.
6. Dust Particle Positions
The coordinates are calculated for five dust particles located closest to the narrowest point of the trail. These particles are named as follows: FarLeft, Left, Middle, Right, and FarRight particles. It is recommended to align your telescope with the Middle particle's position, as this provides the most accurate trail orientation. The other particles offer guidance on the trail's orientation within your telescopic field of view.
7. Trail Positions
Trail positions are based on the findings of Gritsevich et al. 2022 and are provided for various months, including September 2023, November 2023, January 2024, July 2024, and October 2024. All scripts included in the package are designed to calculate position data for the entire period from September 2023 to March 2025. To achieve the highest accuracy, select the script that corresponds to the nearest trail position relative to your specific observing date and time.
8. Image Subtraction
For image subtraction, it is recommended to use CCD images taken over two consecutive nights. Employ an unfiltered luminance filter for this purpose.
9. Brightness and Visibility
The most recent observations of the dust trail, to the best of our knowledge, were conducted by Jorma Ryske in February 2023. These observations confirmed the positioning of the dust trail as predicted. It is expected that the dust trail will maintain for some time a nearly consistent brightness level starting from September 2023. Further research is needed to assess the brightness of the dust trail at the southern node.
10. Particle Sizes
Particle sizes vary at the northern node, with larger particles present starting in September 2023 and finer dust particles predominant by October 2024. At the southern node, fine dust particles are found at the narrowest point of the trail. Additionally, there is a second, extremely dim trail view that is not expected to be observable. By October 2024, the head mass of the trail, consisting mainly of larger particles with an abundance of middle-sized particles, approaches the vicinity of the southern node.
11. Dust Trail Width and Comet's Orbital Plane
Our previous findings highlighted the hourglass shape of the dust trail, indicating that the trail's width varies along its path. Trail width at the northern node is estimated to be in September 2023 approximately 40 arc seconds. The trail is wider at the southern node than at the northern node. In our trail positions, the southern trail measures approximately 2 arc minutes in width at its narrowest point when Earth is not in the comet's orbital plane. This width naturally fluctuates depending on Earth's alignment with the comet's orbital plane. A narrower width of the trail results in a higher particle density, which in turn increases the trail's surface brightness. For ground-based observations, the most favorable geometry occurs when Earth crosses the comet's orbital plane. Earth intersects Holmes' orbital plane twice a year, in February and August.
12. Collaboration Opportunities
For additional in-depth information and references, please refer to the provided resources. We would be delighted to receive updates from your observing campaigns. We eagerly anticipate the possibility of collaborating on joint publications and the dissemination of research findings. In Gritsevich et al. 2022, we have identified open research questions that could be addressed with the help of additional observations. Your contributions are invaluable for advancing the current understanding of cometary outbursts and the subsequent evolution of dust trails. Together, we can explore new horizons in planetary science and share our discoveries with the scientific community and beyond
The fireball of November 24, 1970, as the most probable source of the Ischgl meteorite
No full textGritsevich, M. et al.-- Full list of authors: Gritsevich, Maria; Moilanen, Jarmo; Visuri, Jaakko; Meier, Matthias M. M.; Maden, Colin; Oberst, Jürgen; Heinlein, Dieter; Flohrer, Joachim; Castro-Tirado, Alberto J.; Delgado-García, Jorge; Koeberl, Christian; Ferrière, Ludovic; Brandstätter, Franz; Povinec, Pavel P.; Sýkora, Ivan; Schweidler, Florian.-- This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.The discovery of the Ischgl meteorite unfolded in a captivating manner. In June 1976, a pristine meteorite stone weighing approximately 1 kg, fully covered with a fresh black fusion crust, was collected on a mountain road in the high-altitude Alpine environment. The recovery took place while clearing the remnants of a snow avalanche, 2 km northwest of the town of Ischgl in Austria. Subsequent to its retrieval, the specimen remained tucked away in the finder's private residence without undergoing any scientific examination or identification until 2008, when it was brought to the University of Innsbruck. Upon evaluation, the sample was classified as a well-preserved LL6 chondrite, with a W0 weathering grade, implying a relatively short time between the meteorite fall and its retrieval. To investigate the potential connection between the Ischgl meteorite and a recorded fireball event, we have reviewed all documented fireballs ever photographed by German fireball camera stations. This examination led us to identify the fireball EN241170 observed in Germany by 10 different European Network stations on the night of November 23/24, 1970, as the most likely candidate. We employed state-of-the-art techniques to reconstruct the fireball's trajectory and to reproduce both its luminous and dark flight phases in detail. We find that the determined strewn field and the generated heat map closely align with the recovery location of the Ischgl meteorite. Furthermore, the measured radionuclide data reported here indicate that the pre-atmospheric size of the Ischgl meteoroid is consistent with the mass estimate inferred from our deceleration analysis along the trajectory. Our findings strongly support the conclusion that the Ischgl meteorite originated from the EN241170 fireball, effectively establishing it as a confirmed meteorite fall. This discovery enables to determine, along with the physical properties, also the heliocentric orbit and cosmic history of the Ischgl meteorite. ©2024 The Authors. Meteoritics & Planetary ScienceThis work received support from the Academy of Finland project no. 325806 (PlanetS), the Finnish Geospatial Research Institute, the Spanish Ministry of Science, Innovation and Universities project PID2020-118491GB-I00, Junta de Andalucía grant P20_010168, the Centro de Excelencia Severo Ochoa grant CEX2021-001131-S funded by MCIN/AEI/10.13039/501100011033, and the Slovak Science and Grant Agency VEGA project No. 1/0487/23. We are grateful for the support provided through the special-order contract D/957/67295888 with the DLR. The program of development within Priority-2030 is acknowledged for supporting the research at UrFU. Our sincere appreciation goes to the Ondřejov Observatory and the establishment of an effective all-sky meteor observation program in Germany, which made this study possible. We extend our gratitude to the retired staff at the Max-Planck-Institut für Kernphysik, Heidelberg. Special thanks are also due to Dr. Hugo Fechtig, former director at the Max-Planck-Institut für Kernphysik, and Günther Hauth (1933–2000), the MPIK technician, who dedicated three decades to deploying and caring for the German EN stations. Our heartfelt thanks go to the volunteer operators of the EN cameras for their patience and dedication over the years. We are also grateful to André Knöfel and Michael Matiu for providing historical weather data and useful discussions. We thank Emilio Fernández-García for his proactive and practical support during the preparation of this paper. We are grateful to Natalia Barri for her excellent help in designing the cover image for this issue of Meteoritics & Planetary Science, showcasing the findings of this study.With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2021-001131-S).Peer reviewe
Ablation and Drag Modeling for Reentry of a Blunt Body with Complex Geometry
No full textAn analytical modeling to describe hypersonic movement of a blunt body in an atmosphere is considered. The body is taken to be of unknown shape with complex geometry. We permit further changes in the body shape during the whole luminous part of an atmospheric trajectory. Using the basic differential equations one can introduce the dimensionless parameters describing a problem. Then the study takes an approach that models the body’s mass and other properties based on the height and rate of body deceleration in an atmosphere, which also provides us a good link for better understanding accompanying radiation processes. The model is fitting to the actual data of observations, by selecting key dimensionless parameters describing drag, ablation and rotation rate of a body. The obtained parameters explicitly characterize the ability of entering body to survive an atmospheric entry and reach the ground
New methodology to determine the terminal height of a fireball
No full textDespite ablation and drag processes associated with atmospheric entry of meteoroids were a subject of intensive study over the last century, little attention was devoted to interpret the observed fireball terminal height. This is a key parameter because it not only depends on the initial mass, but also on the bulk physical properties of the meteoroids and hence on their ability to ablate in the atmosphere. In this work we have developed a new approach that is tested using the fireball terminal heights observed by the Meteorite Observation and Recovery Project operated in Canada between 1970 and 1985 (hereafter referred as MORP). We then compare them to the calculation made. Our results clearly show that the new methodology is able to forecast the degree of deepening of meteoroids in the Earth's atmosphere. Then, this approach has important applications in predicting the impact hazard from cm- to meter-sized bodies that are represented, in part, in the MORP bolide list.Peer reviewe
Impact hazard associated with large meteoroids from disrupted asteroids and comets
No full textEl impacto de grandes fragmentos desprendidos de cometas y asteroides contra la Tierra puede llegar a ser muy peligroso. Recientemente, sucesos como Chelyabinsk (2013), Carancas (2007) o Tunguska (1908) han demostrado la capacidad que tienen los meteoroides con diámetros entre 1 y 100 m para devastar grandes extensiones y amenazar a la población local, ya sea mediante la liberación de energía en la atmósfera o el impacto en la superficie. A pesar de la baja frecuencia de este tipo de sucesos, la preocupación entre agencias espaciales y otras iniciativas de defensa planetaria es creciente, y ya están elaborando tácticas de mitigación ante posibles impactos. Este interés se extiende también en la comunidad científica. Además, el estudio de los meteoroides que impactan la atmósfera terrestre revela valiosa información sobre sus progenitores, los mecanismos que siguen para llegar a la Tierra, y su habilidad para amenazar nuestro planeta. Así, esta tesis tiene por objeto dar respuesta a una serie de interrogantes sobre la física asociada al impacto y a las condiciones pre-impacto. Este trabajo comienza explorando aspectos complejos de la dinámica orbital de meteoroides a través de dos fenómenos excepcionales. Por un lado, la actividad anual de las Úrsidas aumenta cuando ciertos enjambres de meteoroides desprendidos del cometa 8P/Tuttle hace 620 años impactan la Tierra encontrándose el cometa en su afelio orbital. Los incrementos de actividad cuando el cometa está en su afelio no son comunes y por tanto las Úrsidas ofrecen nuevas claves sobre la mecánica orbital. Por otro lado, si la trayectoria atmosférica de un meteorito, como es Annama, se obtiene de manera precisa, éste se puede vincular orbitalmente con un cuerpo celeste. Dada la rápida evolución orbital de los NEA (considerados posibles progenitores) este estudio nos permite acotar mejor sus órbitas y predecir futuros impactos. La segunda parte de la tesis versa sobre la caracterización del vuelo atmosférico de un meteoroide. Los modelos actuales son capaces de considerar la ablación y fragmentación de un meteoroide en la atmósfera, pero aún no es posible comprender completamente, ni de manera observacional ni numérica, el vuelo hipersónico de un meteoroide en la región definida por la mesosfera y baja termosfera donde el gas se considera rarificado. Esta tesis presenta la primera comprobación observacional de los regímenes de vuelo para meteoroides centimétricos a estas alturas, y discute las consecuencias que origina la formación de una onda de choque en la física del vuelo del meteoroide. Además, las ondas de choque están íntimamente relacionadas con la energía depositada por el meteoroide a distintas alturas; magnitud que también se puede acotar conociendo su altura terminal. Así, esta tesis se ofrece también una nueva metodología para calcular estas alturas. Los resultados obtenidos son muy precisos y muestran que el cálculo de las alturas terminales es muy útil para derivar otros parámetros del vuelo del meteoroide. Es más, el planteamiento usado ofrece una nueva manera de clasificar los impactos de meteoroides y mejorar escalas anteriores. Por último, se discute la extrapolación de los estudios anteriores a cuerpos de diferentes tamaños. Aunque menos peligrosos, los impactos de cuerpos inferiores a 1 metro son los mas frecuentes y, en consecuencia, nutren las bases de datos y resultan fundamentales para abordar el estudio de meteoroides. La extrapolación de las conclusiones obtenidas previamente a objetos mas grandes puede revelar claves sobre la física subyacente y aportar nuevas predicciones sobre el riesgo asociado a impactos energéticos. Los resultados de esta investigación proveen también un enfoque alternativo al desarrollo de modelos numéricos, tanto actuales como futuros, que hasta hoy han sido fundamentales para afrontar el estudio de meteoroides.Large meteoroid fragments disrupted from asteroids and comets may encounter the Earth along their orbits, posing extremely hazardous scenarios. Contemporary events like Chelyabinsk (2013), Carancas (2007) or Tunguska (1908) demonstrated that meteoroids in the diameter range of 1 to 100 m can devastate large areas and injure local population through the associated energetic blast, or even produce casualties due to localized crater excavation. Despite the relatively low frequency of these events, they have become a major concern within space agencies and other planetary defense initiatives which are currently developing impact mitigation tactics. This is in line with the growing popularity of this subject in the scientific community. The number of yet unresolved questions underlying the pre- and impact physics motivates the work carried out in this thesis. The study of meteoroids that encounter the terrestrial atmosphere provides valuable clues about their progenitors, their delivery mechanisms to Earth, and their ability to threaten our planet. This thesis starts by exploring the complexity of meteoroid dynamics through two exceptional phenomena. On the one hand, a limited number of meteoroid dust trails detached from the comet 8P/Tuttle 620 years ago impact the Earth when the parent comet is in its aphelion, thus increasing the activity of the annual Ursid meteor shower. Aphelion-related increases in a meteor shower activity are uncommon and hence the Ursids offer a new perspective of orbital mechanics. On the other hand, meteorite falls, like Annama, can be orbitally linked to celestial bodies if their atmospheric trajectories are accurately recorded. Exploring these parental relationships offer the opportunity to overcome the uncertainties emerged from the short-term orbital evolution of near-Earth objects and ultimately predict future impacts. The second part of this thesis focuses on the characterization of the atmospheric flight of a meteoroid. While up to-date re-entry models that account for the meteoroid ablation and fragmentation are common, no observational or modelling studies have resolved the intricacies associated with the mesosphere and lower thermosphere region for meteoroids travelling at hypersonic velocities and in rarefied gas flow conditions. This thesis presents the first observational validation of the flight flow regimes of centimeter-sized meteoroids and provides a new insight into the consequences for the meteoroid flight physics due to the generation of a shock wave. Meteoroid shock waves are also intimately related to the meteoroid energy deposition at different heights, which can alternatively be stated from the analysis of the terminal height of the meteoroid's trajectory. A new approach capable to precict the terminal heights is outlined in this thesis. The results show that, besides the great accuracy achieved, the calculated terminal heights are a valuable input to the derivation of atmospheric flight parameters. Furthermore, the approach taken provides a new way of classifying impacting meteoroids that improve previous classification scales. Finally, a discussion of the implications of the previous analysis to impacting bodies of different sizes is carried out. Since Earth impacts by meter-sized or smaller bodies are more frequent, the study of sub-metric meteoroids provides a wide catalogue of events that can be crucial to understand the meteor physics. Being able to extrapolate the behaviour of these bodies to asteroid sizes can provide new clues on the underlying physics and make predictions concerning the degree of hazard associated with energetic events. The results of this work also provide feedback and an alternative approach to current and foreseen numerical simulations that were seen in the past as the only way to deal with these challenging encounters
Penetration of Probes and Natural Cosmic Bodies into Planetary Atmospheres: Mathematical Interpretation of Observational Data
No full textThis presentation was part of the session : Poster SessionsSixth International Planetary Probe WorkshopThe approximation of the actual data using theoretical models in general makes it possible to achieve additional estimates, which do not directly follow from the observations. For example, the correct mathematical modeling of meteor events in the atmosphere is necessary for further estimates of the key parameters, including the extra-atmospheric mass, the ablation coefficient, and the effective enthalpy of evaporation of entering bodies. In turn, this information is needed by some applications, namely, those aimed at studying the problems of asteroid and comet security, to develop measures of planetary defense, and to determine the bodies that can reach Earth's surface.
In the present report, an analytical model of the atmospheric entry is calculated using the altitude and rate of the body deceleration in the atmosphere from the data of actual observations. With this purpose the strict mathematical algorithm to find basic dynamic parameters of the theoretical relationship between the height and the velocity of the body that help to fit observations along the luminous part of the trajectories in the best way is suggested. The main difference from previous studies is that the given observations are approximated using the analytical solution of the fundamental differential equations of the hypersonic flight of the body.
The proposed general approach helps in understanding the extensive observational data of the deceleration of probes and natural cosmic bodies in the upper layers of the terrestrial atmosphere under conditions when the sizes, mass of a body and also aerodynamic flight regime are in advance unknown.
New model presented in the report was applied to well-known real impacts. These are several famous meteorite-producing fireballs and the STARDUST Sample Return Capsule (a hypersonic phase). The estimate of mass of SRC obtained using the data of actual observations is quite close to its real value of 45.8 kg.
On the basis of new mathematical interpretation of observational data in the report also it will be noted that the major part of the luminous segment of the trajectories of large bodies corresponds to continuous medium flow, while the condition of a free molecular flow holds outside this segment. The maximum brightness altitude is smaller than that at which a strong bow shock is formed. At a flow past body in a rate of the continuous medium, the basic contribution to luminescence gives radiation of heat atmospheric gas near the body. So, luminosity of a body at its hypersonic flight in the atmosphere does not defined only by radiation of vapor of a body material, arising owing to evaporation of its surface. Therefore some of applied earlier methods for evaluating fireballs parameters from observational data are not correct.Lomonosov Moscow State Universit
Constraining the luminous efficiency of meteors
No full textInternational audience► We adopt a new technique to interpret brightness of a meteor. ► Both changes in meteoroid mass and velocity are considered. ► Meteor luminosity is expressed analytically as a function of its velocity. ► We test methodology on 3 MORP fireballs
The challenges in hypervelocity microphysics research on meteoroid impacts into the atmosphere
No full textMeteor science contributes greatly to the study of the Solar System and the Earth's atmosphere. However, despite its importance and very long history, meteor science still has a lot to explore in the domain of meteor plasma microphysics and the meteor-ionosphere interaction. Meteors are actually a difficult target for high-resolution observations, which leads to the need for more ambitious interdisciplinary observational setups and campaigns. We describe some recent developments in the physics of meteor flight and microphysics of meteor plasma and argue that meteor science should be fully integrated into the science cases of large astronomical facilities.Peer reviewe
Inferring Fireball Velocity Profiles and Characteristic Parameters of Meteoroids From Incomplete Data Sets
No full textPeer reviewe
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