Search

Some active asteroids have been proposed to be the result of impact events. Because active asteroids are generally discovered serendipitously only after their tail formation, the process of the impact ejecta evolving into a tail has never been directly observed. NASA's Double Asteroid Redirection Test (DART) mission, apart from having successfully changed the orbital period of Dimorphos, demonstrated the activation process of an asteroid from an impact under precisely known impact conditions. Here we report the observations of the DART impact ejecta with the Hubble Space Telescope (HST) from impact time T+15 minutes to T+18.5 days at spatial resolutions of ~2.1 km per pixel. Our observations reveal a complex evolution of ejecta, which is first dominated by the gravitational interaction between the Didymos binary system and the ejected dust and later by solar radiation pressure. The lowest-speed ejecta dispersed via a sustained tail that displayed a consistent morphology with previously observed asteroid tails thought to be produced by impact. The ejecta evolution following DART's controlled impact experiment thus provides a framework for understanding the fundamental mechanisms acting on asteroids disrupted by natural impact., accepted by Nature

The Traspena meteorite fell on 2021 January 18 about 20 km south-east of the city of Lugo (Galiza, Spain), shortly after a huge and bright fireball crossed the sky for 4.84 s. Astrometric measurements obtained from the fireball cameras of the Universidade de Santiago de Compostela (USC) as well as from many casual videos were used to determine the atmospheric trajectory of this meteoroid which penetrated the atmosphere and generated sound waves that were detected at three seismic stations. The original meteoroid had a diameter of about 1.15 m and a mass around 2620 kg. It impacted the Earth’s atmosphere with a steep entry angle of about 76 . ◦7 from a height of 75.10 km until fading away at 15.75 km with a velocity of 2.38 km s −1 . Before the impact, this small asteroid was orbiting the Sun with a semimajor axis of 1.125 au, a moderate eccentricity of 0.386, and a low inclination of 4 . ◦55. A weak evidence of dynamic link with the PHA (Potential Hazardous Asteroid) Minos was investigated. During the atmospheric entry, two major fragmentation events occurred between heights of 35 and 29 km at aerodynamic pressures between 1 and 5 MPa. The strewn field was computed after calculating the individual dark flights of the main body along with two smaller fragments. For- tunately, 2 month after the superbolide, a 527-g meteorite was found. It was examined using several geochemical and petrographic analyses which allowed us to classify it as a moderately shocked (S3) L5 ordinary chondrite with a bulk density of 3.25 g cm −3 ., This paper was supported by the Xunta de Galicia (Spain) under the ED431B 2020/38 grant.

Carbonaceous chondrites (CCs) can beconsidered cosmic aggregates containingprotoplanetary disk components. Modern analytical techniques allow us to identify CCsunaffected by thermal or aqueous alterationprocesses, having a pristine nature. Such ahighly unequilibrated meteorites allow us toget clues on the early Solar System (ESS), astheir components are ancient materials retentive of chemical clues on their formation.The information they contain is valuable to beapplied to better understand protoplanetary disks.

While no known asteroid poses a threat to Earth for at least the next century, the catalog of near-Earth asteroids is incomplete for objects whose impacts would produce regional devastation. Several approaches have been proposed to potentially prevent an asteroid impact with Earth by deflecting or disrupting an asteroid. A test of kinetic impact technology was identified as the highest priority space mission related to asteroid mitigation. NASA's Double Asteroid Redirection Test (DART) mission is the first full-scale test of kinetic impact technology. The mission's target asteroid was Dimorphos, the secondary member of the S-type binary near-Earth asteroid (65803) Didymos. This binary asteroid system was chosen to enable ground-based telescopes to quantify the asteroid deflection caused by DART's impact. While past missions have utilized impactors to investigate the properties of small bodies those earlier missions were not intended to deflect their targets and did not achieve measurable deflections. Here we report the DART spacecraft's autonomous kinetic impact into Dimorphos and reconstruct the impact event, including the timeline leading to impact, the location and nature of the DART impact site, and the size and shape of Dimorphos. The successful impact of the DART spacecraft with Dimorphos and the resulting change in Dimorphos's orbit demonstrates that kinetic impactor technology is a viable technique to potentially defend Earth if necessary., Comment: Accepted by Nature

Anghel, S., et al., The increase in detector sensitivity and availability in the past three decades has allowed us to derive knowledge of the meteoroid flux and impact energy into the Earth's atmosphere. We present the multi-instrument detected 2018 December 22 fireball over Western Pyrenees, and compare several techniques aiming to obtain a reliable method to be used when measuring impacts of similar scale. From trajectory data alone, we found a bulk density of 3.5 g cm-3 to be the most likely value for the Pyrenean meteoroid. This allowed to further constrain the dynamic mass, which translated into a kinetic energy of 1 ton TNT (4.184 × 109 J). For the second energy derivation, via the fireball's corrected optical radiation, we obtained a more accurate empirical relation measuring well-studied bolides. The result approximates to 1.1 ton TNT, which is notably close to the nominal dynamic result, and agrees with the lower margin of the seismic-based energy estimation, yet way lower than the infrasound estimate. Based on the relation derived in this study, we consider the nominal estimate from both the dynamic and photometric methods to be the most accurate value of deposited energy (1 ton TNT). We show that the combination of these two methods can be used to infer the meteoroid density. Among the methods presented in this paper, we found that the optical energy is the most reliable predictor of impact energy near the ton TNT-scale., S. Anghel and D. A. Nedelcu were supported by a grant of the Romanian Ministry of Research and Innovation, CCCDI - UEFISCDI, project number PN-III-P1-1.2-PCCDI-2017-0226/16PCCDI/2018, within PNCDI III. EP-A and JMT-R acknowledge funding from PGC2018-097374-B-I00 (MCI-AEI-FEDER, EU). M. Birlan work was partly supported by SEEING-IEA CNRS program. R. Hueso and A. Sánchez-Lavega were supported by Diputación Foral de Bizkaia and Gobierto Vasco IT1366-19.

Meteor physics can provide new clues about the size, structure, and density of cometary disintegration products, establishing a bridge between different research fields. From meteor magnitude data we have estimated the mass distribution of meteoroids from different cometary streams by using the relation between the luminosity and the mass obtained by Verniani. These mass distributions are in the range observed for dust particles released from comets 1P/Halley and 81P/Wild 2 as measured from spacecraft. From the derived mass distributions, we have integrated the incoming mass for the most significant meteor showers. By comparing the mass of the collected interplanetary dust particles (IDPs) with that derived for cometary meteoroids a gap of several orders of magnitude is encountered. The largest examples of fluffy particles are clusters of IDPs no larger than 100 μm in size (or 5 × 10–7 g in mass) while the largest cometary meteoroids are centimeter-sized objects. Such gaps can be explained by the fragmentation in the atmosphere of the original cometary particles. As an application of the mass distribution computations we describe the significance of the disruption of fragile comets in close approaches to Earth as a more efficient (and probably more frequent) way to deliver volatiles than direct impacts. We finally apply our model to quantify the flux of meteoroids from different meteoroid streams, and to describe the main physical processes contributing to the progressive decay of cometary meteoroids in the interplanetary medium., JMTR acknowledges financial support by the research project(PGC2018 097374-B-I00, funded by FEDER/Ministerio de Ciencia e Innovación – Agencia Estatal de Investigación. JB acknowledges the continuing support by the Deutsche Forschungsgemeinschaft and the Deutsches Zentrum für Luft- und Raumfahrt.

Statler et al., NASA’s Double Asteroid Redirection Test (DART) is the first full-scale test of an asteroid deflection technology. Results from the hypervelocity kinetic impact and Earth-based observations, coupled with LICIACube and the later Hera mission, will result in measurement of the momentum transfer efficiency accurate to ∼10% and characterization of the Didymos binary system. But DART is a single experiment; how could these results be used in a future planetary defense necessity involving a different asteroid? We examine what aspects of Dimorphos’s response to kinetic impact will be constrained by DART results; how these constraints will help refine knowledge of the physical properties of asteroidal materials and predictive power of impact simulations; what information about a potential Earth impactor could be acquired before a deflection effort; and how design of a deflection mission should be informed by this understanding. We generalize the momentum enhancement factor β, showing that a particular direction-specific β will be directly determined by the DART results, and that a related direction-specific β is a figure of merit for a kinetic impact mission. The DART β determination constrains the ejecta momentum vector, which, with hydrodynamic simulations, constrains the physical properties of Dimorphos’s near-surface. In a hypothetical planetary defense exigency, extrapolating these constraints to a newly discovered asteroid will require Earth-based observations and benefit from in situ reconnaissance. We show representative predictions for momentum transfer based on different levels of reconnaissance and discuss strategic targeting to optimize the deflection and reduce the risk of a counterproductive deflection in the wrong direction., This work was supported in part by the DART mission, NASA contract No. 80MSFC20D0004 to JHU/APL. Some of this work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004). S.C. acknowledges funding through the Crosby Fellowship of the Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology. E.D., S.I., A.L., M.P., A.R., and P.T. are grateful to the Italian Space Agency (ASI) for financial support through agreement No. 2019-31-HH.0 in the context of ASI’s LICIACube mission, and agreement No. 2022-8-HH.0 for ESA’s Hera mission. R.L. appreciates the funding from the European Union’s Horizon 2020 research and innovation program, grant agreement No. 870377 (project NEO-MAPP). P.M. acknowledges funding support from the French space agency CNES, ESA and the European Union’s Horizon 2020 research and innovation program under grant agreement No. 870377 (project NEO-MAPP). R.M. acknowledges support from a NASA Space Technology Graduate Research Opportunities (NSTGRO) Award (80NSSC22K1173). R.N. acknowledges support from NASA/FINESST (NNH20ZDA001N). J.O. and I.H. were supported by the Spanish State Research Agency (AEI) project No. MDM-2017-0737 Unidad de Excelencia “María de Maeztu”—Centro de Astrobiología (CSIC-INTA). They are also grateful for all logistical support provided by Instituto Nacional de Técnica Aeroespacial (INTA). S.R.S. acknowledges support from the DART Participating Scientist Program, grant No. 80NSSC22K0318. J.M.T.R. was funded by FEDER/Ministerio de Ciencia e Innovación—Agencia Estatal de Investigación of Spain (grant No. PGC2018-097374-B-I00).

On February 16, 2021, an artificial object moving slowly over the Mediterranean was recorded by the Spanish Meteor Network (SPMN). Based on astrometric measurements, we identified this event as the reentry engine burn of a SpaceX Falcon 9 launch vehicle’s upper stage. To study this event in detail, we adapted the plane intersection method for near-straight meteoroid trajectories to analyze the slow and curved orbits associated with artificial objects. To corroborate our results, we approximated the orbital elements of the upper stage using four pieces of “debris” cataloged by the U.S. Government’s Combined Space Operations Center. Based on these calculations, we also estimated the possible deorbit hazard zone using the MSISE90 model atmosphere. We provide guidance regarding the interference that these artificial bolides may generate in fireball studies. Additionally, because artificial bolides will likely become more frequent in the future, we point out the new role that ground-based detection networks can play in the monitoring of potentially hazardous artificial objects in near-Earth space and in determining the strewn fields of artificial space debris. [Figure not available: see fulltext.], This research was supported by the research project (Grant No. PGC2018-097374-B-I00, PI: JMT-R), which is funded by FEDER/Ministerio de Ciencia e Innovación–Agencia Estatal de Investigación. This project has also received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Programme (Grant No. 865657) for the project “Quantum Chemistry on Interstellar Grains” (QUANTUMGRAIN).

The petrology and mineralogy of shock melt veins in the L6 ordinary chondrite host of Villalbeto de la Peña, a highly shocked, L chondrite polymict breccia, have been investigated in detail using scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and electron probe microanalysis. Entrained olivine, enstatite, diopside, and plagioclase are transformed into ringwoodite, low-Ca majorite, high-Ca majorite, and an assemblage of jadeite-lingunite, respectively, in several shock melt veins and pockets. We have focused on the shock behavior of diopside in a particularly large shock melt vein (10 mm long and up to 4 mm wide) in order to provide additional insights into its high-pressure polymorphic phase transformation mechanisms. We report the first evidence of diopside undergoing shock-induced melting, and the occurrence of natural Ca-majorite formed by solid-state transformation from diopside. Magnesiowüstite has also been found as veins injected into diopside in the form of nanocrystalline grains that crystallized from a melt and also occurs interstitially between majorite-pyrope grains in the melt-vein matrix. In addition, we have observed compositional zoning in majorite-pyrope grains in the matrix of the shock-melt vein, which has not been described previously in any shocked meteorite. Collectively, all these different lines of evidence are suggestive of a major shock event with high cooling rates. The minimum peak shock conditions are difficult to constrain, because of the uncertainties in applying experimentally determined high-pressure phase equilibria to complex natural systems. However, our results suggest that conditions between 16 and 28 GPa and 2000–2200 °C were reached.

Meteorites originating from primitive C-type asteroids are composed of materials from the Sun’s protoplanetary disk, including up to a few per cent organic carbon. In contrast, some interplanetary dust particles and micrometeorites have much higher carbon contents, up to >90%, and are thought to originate from icy outer Solar System bodies and comets. Here we report an approximately 100-µm-diameter very carbon-rich clast, with highly primitive characteristics, in the matrix of a CR2 chondrite, LaPaz Icefield 02342. The clast may represent a cometary building block, largely unsampled in meteorite collections, that was captured by a C-type asteroid during the early stages of planet formation. The existence of this cometary microxenolith supports the idea of a radially inward transport of materials from the outer protoplanetary disk into the CR chondrite reservoir during the formation of planetesimals. Moreover, the H-isotopic composition of the clast is suggestive of a temporal evolution of organic isotopic compositions in the comet-forming region of the disk. The composition and characteristics of a C-rich clast within the LaPaz Icefield 02342 meteorite suggests that the clast is composed of materials related to comets and icy bodies. The clast probably formed in the outer Solar System, was transported inward and finally accreted into LaPaz’s parent body.

Carbonaceous chondrite meteorites are so far the only available samples representing carbon-rich asteroids and in order to allow future comparison with samples returned by missions such as Hayabusa 2 and OSIRIS-Rex, it is important to understand their physical properties. Future characterization of asteroid primitive classes, some of them targeted by sample-return missions, requires a better understanding of their mineralogy, the consequences of the exposure to space weathering, and how both affect the reflectance behaviour of these objects. In this paper, the reflectance spectra of two chemically related carbonaceous chondrites groups, precisely the Vigrano (CVs) and Karoonda (CKs), are measured and compared. The available sample suite includes polished sections exhibiting different petrologic types: from 3 (very low degree of thermal metamorphism) to 5 (high degree of thermal metamorphism). We found that the reflective properties and the comparison with the Cg asteroid reflectance class point towards a common chondritic reservoir from which the CV-CK asteroids collisionally evolved. In that scenario, the CV and CK chondrites could be originated from 221 Eos asteroid family, but because of its collisional disruption, both chondrite groups evolved separately, experiencing different stages of thermal metamorphism, annealing, and space weathering., This research has been funded by the research project (PGC2018-097374-B-I00, P.I.: JMT-R), funded by FEDER/Ministerio de Ciencia e Innovacion – Agencia Estatal de Investigación. ST is hired in the framework of that research project

There is a very significant body of evidence for a dense Martian atmosphere during the Noachian period, about 3.8 Ga ago. At that point in the evolution of the red planet water was present in the surface of Mars, and ancient surface features indicate that it flew through significant regions of its surface. We have studied Allan Hills 84001. an orthopiroxenite formed about 4.1 Ga ago. It is a meteorite widely known because [1] found microscopic structures that were suggested to be magnetotactic microbe fossils. In particular, in our CSIC laboratory I have studied with some of my PhD students the carbonate globules contained in this meteorite [2]. We discovered in a ALH84001,82 thin section (Fig. 1) that they were formed near the rock fractures, as consequence of the precipitation of Mg- and Fe-rich carbonates from an aqueous solution. Figure 1. Thin section of ALH 84001. The square grid is mm-sized. This optical microscope transmitted light reveals the main minerals forming the rock and many fractures as consequence, at least, of two impacts while the rock formed part of Mars’ surface. Water penetrated into the fractures and produced the carbonate globules (see also Fig. 2) Interestingly, we found distinctive layers in the walls of the carbonate globules. They indicate that the globules growth occurred under several flooding stages. As they exhibit differentiated elemental chemistry, it could reflect distinctive chemical solutes, being probably evidence of chemically-distinguishable fluids produced by environmental differences [3-4]. To explain liquid water presence at that time is challenging because the young Sun was less luminous than today: about was ~25% lower than nowadays. Consequently, being Mars about 1.5 times more distant from the Sun than the Earth, the solar energy available on Mars was ~1/3 of what gets the Earth today. Then we need to invoke an atmospheric greenhouse effect. Early Mars atmospheric composition is not well constrained, but it was probably mostly composed of CO2 with a surface pressure between a few hundreds of mbars to a few bars [5]. Large amounts of CO2 and H2O were probably released by the substantial Tharsis volcanism during the mid-Noachian. These species probably contributed, but other greenhouse gases have been proposed to solve the enigma (Fig. 3). Some of them are photochemically unstable and rapidly exhausted, unless continuously outgassed by volcanoes. The discovery of sulphate salts in Mars’ surface [5] have promoted the relevance of SO2 as greenhouse, and strength the possibility of an astrobiological catalytic environment in presence of water and N-bearing species [3-4]. The study at microscale of Martian meteorites (exemplified with the previous ALH84001 study) can be useful to understand the geological context and get new insight about the presence of biosignatures. Figure 2. ALH 84001 carbonate globules. Left) Optical microscope transmitted light where the rounded globules appear in brown. Right) One of the globules emphasized with a EDX mapping to show the different Fe-content of the layering. Concerning the presence of water in Mars’ surface and subsurface at different epochs, the evidence arrived from Martian meteorites indicates a progressive water depletion probably due to the evolving surface environment, finally reaching the current harsh conditions. For example, clear evidence for Amazonian acidic liquid water on Mars surface was found, producing aqueous alteration minerals [5]. A dense atmosphere associated with volcanic outgassing during the Noachian period could have promoted significant deceleration, and disruption of fragile chondritic asteroids. In such circumstances the arrival of meteorite powders was a way to promote catalytic reactions at the Martian surface. Given that the early Mars was subjected to a continuous rain of chondritic materials when it experienced significant hydrothermal activity, I identify a potential astrobiology environment All this growing evidence about the role of the aqueous alteration and the formation of secondary minerals also supports the evidence for a wet Mars environment. The role of collisional gardening in the early stages of Mars' evolution is also out of doubt from the study of the oldest Martian meteorites [6]. In fact, new evidence for a massive water sequestration has been recently presented [7]. To search for the pathways of water towards the interior of Mars we should study impact fractures in the crust of Mars, and their role to host potential biota. Probably the transient nature of aquifers in Mars was restricting the regions to develop life, but future mission searches in depth could get new clues. ACKNOWLEDGEMENTS This research has been funded by PGC2018-⁠097374-⁠B-⁠I00 (MCI-⁠AEI-⁠FEDER, UE). US Antarctic meteorites are recovered by the Antarctic Search for Meteorites (ANSMET) program funded by NSF and NASA, and characterized and curated by the Department of Mineral Sciences of the Smithsonian Institution and Astromaterials Acquisition and Curation Office at NASA Johnson Space Center. REFERENCES [1] McKay D. S. et al. (1996) Search for Past Life on Mars: Possible Relic Biogenic Activity in Martian Meteorite ALH 84001. Science 273, 924-930. [2] Moyano-Cambero, C.E., Trigo-Rodríguez, J.M., Benito, M.I., et al. (2017) Petrographic and geochemical evidence for multiphase formation of carbonates in the Martian orthopyroxenite Allan Hills 84001, Meteoritics & Planetary Science 52, 1030-1047. [3] Trigo-Rodriguez, J. M., Moyano-Cambero, C. E., Donoso, J. A., Benito-Moreno, M. I., Alonso-Azcárate, J. (2018) Clues on Past Climatic Environments and Subsurface Flow in Mars from Aqueous Alteration Minerals Found in Nakhla and Allan Hills 84001 Meteorites, 49th LPSC, LPI Contribution No. 2083, id.1448 [4] Trigo-Rodríguez, J. M., Moyano-Cambero, C. E., Benito-Moreno, M. I., Alonso-Azcárate, J. (2018) Growth of carbonate globules in ALH 84001 Martian orthopyroxenite by transient floods in a chemically variable environment. Proceedings of the Mars Science Workshop From Mars Express to ExoMars, held 27-28 February 2018 at ESAC, Madrid, Spain, id.71 [5] Fernández-Remolar D.C. et al., (2011) The environment of early Mars and the missing carbonates. Meteoritics & Planetary Science, Volume 46, 1447-1469. [6] Humayun M. et al. (2013) Origin and age of the earliest Martian crust from meteorite NWA 7533. Nature 503, 513-516. [7] Scheller, E. L., Ehlmann, B. L., Hu, Renyu, Adams, D. J., Yung, Y. L. (2021) Long-term drying of Mars by sequestration of ocean-scale volumes of water in the crust. Science 372, 56-62.

Drolshagen, E., et al., [Context] In meteor physics, the luminous efficiency τ is used to convert the meteor's magnitude to the corresponding meteoroid's mass. However, a lack of sufficiently accurate verification methods or adequate laboratory tests mean that discussions around this parameter are a subject of controversy. [Aims] In this work, we aim to use meteor data obtained by the Fireball Recovery and InterPlanetary Observation to calculate the luminous efficiencies of the recorded meteors. We also show the limitations of the methods presented herein. [Methods] Deceleration-based formulas were used to calculate the masses of the pre-atmospheric meteoroids. These can in turn be compared to the meteor brightnesses to assess the luminous efficiencies of the recorded objects. Fragmentation of the meteoroids is not considered within this model. Good measurements of the meteor deceleration are required. [Results] We find τ-values, as well as the shape change coefficients, of 294 meteors and fireballs with determined masses in the range of 10-6-100 kg. The derived τ-values have a median of τmedian = 2.17%. Most of them are of the order of 0.1-10%. We present how our values are obtained, compare them with data reported in the literature, and discuss several methods. A dependence of τ on the pre-atmospheric velocity of the meteor, ve, is noticeable with a relation of τ = 0.0023 ve2.3. Furthermore, a dependence of τ on the initial meteoroid mass, Me, is found with negative linear behaviour in log-log space: τ = 0.48 Me-0.47. [Conclusions] The higher luminous efficiency of fast meteors could be explained by the higher amount of energy released. Fast meteoroids produce additional emission lines that radiate more efficiently in specific wavelengths due to the appearance of the so-called second component of higher temperature. Furthermore, the negative dependence of τ on Me implies that the radiation of smaller meteoroids is more efficient. The results of this study also show the limitations of the ablation-based model for the determination of the luminous efficiency.

In this study, we investigate the ablation properties of bolides capable of producing meteorites. The casual dashcam recordings from many locations of the Chelyabinsk superbolide associated with the atmospheric entry of an 18 m in diameter near-Earth object (NEO) have provided an excellent opportunity to reconstruct its atmospheric trajectory, deceleration, and heliocentric orbit. In this study, we focus on the study of the ablation properties of the Chelyabinsk bolide on the basis of its deceleration and fragmentation. We explore whether meteoroids exhibiting abrupt fragmentation can be studied by analyzing segments of the trajectory that do not include a disruption episode. We apply that approach to the lower part of the trajectory of the Chelyabinsk bolide to demonstrate that the obtained parameters are consistent. To do that, we implemented a numerical (Runge–Kutta) method appropriate for deriving the ablation properties of bolides based on observations. The method was successfully tested with the cases previously published in the literature. Our model yields fits that agree with observations reasonably well. It also produces a good fit to the main observed characteristics of Chelyabinsk superbolide and provides its averaged ablation coefficient σ = 0.034 s km. Our study also explores the main implications for impact hazard, concluding that tens of meters in diameter NEOs encountering the Earth in grazing trajectories and exhibiting low geocentric velocities are penetrating deeper into the atmosphere than previously thought and, as such, are capable of producing meteorites and even damage on the ground., This research was funded by the research project (PGC2018-097374-B-I00, P.I. J.M.T-R), funded by FEDER/Ministerio de Ciencia e Innovación–Agencia Estatal de Investigación. MG acknowledges support from the Academy of Finland (325806). Research at the Ural Federal University was supported by the Russian Foundation for Basic Research (18-08-00074 and 19-05-00028).

The disruption of asteroids and comets produces cm-sized meteoroids that end up impacting the Earth's atmosphere and producing bright fireballs that might have associated shock waves or, in geometrically-favorable occasions excavate craters that put them into unexpected hazardous scenarios. The astrometric reduction of meteors and fireballs to infer their atmospheric trajectories and heliocentric orbits involves a complex and tedious process that generally requires many manual tasks. To streamline the process, we present a software package called SPMN 3D Fireball Trajectory and Orbit Calculator (3D-FireTOC), an automatic Python code for detection, trajectory reconstruction of meteors, and heliocentric orbit computation from video recordings. The automatic 3D-FireTOC package comprises of a user interface and a graphic engine that generates a realistic 3D representation model, which allows users to easily check the geometric consistency of the results and facilitates scientific content production for dissemination. The software automatically detects meteors from digital systems, completes the astrometric measurements, performs photometry, computes the meteor atmospheric trajectory, calculates the velocity curve, and obtains the radiant and the heliocentric orbit, all in all quantifying the error measurements in each step. The software applies corrections such as light aberration, refraction, zenith attraction, diurnal aberration and atmospheric extinction. It also characterizes the atmospheric flight and consequently determines fireball fates by using the $\alpha - \beta$ criterion that analyses the ability of a fireball to penetrate deep into the atmosphere and produce meteorites. We demonstrate the performance of the software by analyzing two bright fireballs recorded by the Spanish Fireball and Meteorite Network (SPMN)., Comment: Published on 10 April 2021

Current statistics on the flux of impactors on the Earth reveal that asteroids with a diameter larger than few hundreds of meters are unlikely to reach the Earth’s orbit, although their potential effects on the life of our planet could be quite catastrophic. The present article assesses a set consisting of four deflection approaches, namely: kinetic impactor, ion beam deflection, enhanced gravity tractor, and laser ablation to be applied to mitigate a hypothetic impact with an asteroid smaller than 250 meters in diameter. This size range corresponds to the most common impactors that occur in timescales of less than 100.000 years. With the current discovery rate for small asteroids, such a range of diameters could be of interest to assess a future impact forecast, and quantify our capacity to react in time. To achieve this, a set of eight criteria are used: build time; active deflection duration; asteroid rotation; asteroid composition; asteroid structure; asteroid shape; level of maturity of a NEA deflection technique; and mission risk. This assessment is carried out with a combination of Multi-Criteria Decision Making tools and fuzzy logic, which enables proper management of imprecise criteria. The valuable knowledge provided by a group of experts enabled the importance of each attribute and the evaluation of these NEA deflection techniques to be quantified. Our results suggest that the kinetic impactor is the best option to deflect mid-size NEAs, whereas for larger asteroids, enhanced gravity tractor, and laser ablation become to be more appropriate., J.M.S.L. is partially supported by grants TIN2017-86647-P and from the Spanish Ministry of Economy and Competitiveness (MINECO), and the Spanish Ministry of Science, Innovation and Universities, respectively. He also acknowledges the support of Grant 19882-GERM-15 from Fundación Séneca (Región de Murcia). M.F.M. appreciates the partial support of Ministerio Español de Economía y Competitividad, grant MTM2015-64373-P (MINECO/FEDER, UE), and Ministerio Español de Ciencia, Innovación y Universidades (Spain), and FEDER (Spain), grant PGC2018-097198-B-I00. JMTR is funded by PGC2018-097374-B-100 from which is project PI (MINECO).

Talk delivered in Europlanet Science Congress online, 21 September 2020 - 09 October 2020, Extremely bright fireballs are rarely recorded events that provide valuable information for meteor science. From the study of these luminous phases is obtained valuable information about the meteoroids physical properties and their origin in the Solar System. Meter-sized meteoroids are consequence of the continuous decay of asteroids and comets, their main parent bodies. The recovery of new meteorites and the study of the dynamic association with comets, asteroids or planetary bodies gives new clues on the physical processes delivering space rocks to Earth. Fireball monitoring tasks differ from most other types of astronomical observations since these events cannot be predicted either in time or direction. For this reason, it is necessary to monitor the sky with full-time coverage. That is the goal of multiple stations fireball systems. However, given the heterogeneous distribution of such initiatives around the globe, some events are unnoticed, and others partially recorded. This is particularly truth for superbolides produced by m-sized bolides that are hitting the atmosphere few times every year. To increase our data on the atmospheric behaviour and the origin of these elusive superbolides, satellite records can play a crucial role in the reconstruction of the trajectory.

14th Europlanet Science Congress, The Moon is no longer a goal in itself but a necessary step for the conquest of space. In this work we focus in the composition of Lunar meteorites as the only objects alongside Apollo, and Luna collected samples, that the scientific community has available to first-hand analyze the Moon. Future Artemis sample return missions will provide new samples to continue learning from our satellite. Given its proximity to our planet, our satellite is an ideal planetary body to use it as a space camp for new technology, to establish a space base, and to test space mining. The continuous depletion of Earth resources put special importance on the exploration of extraterrestrial natural resources potential and the feasibility of its exploitation. After many robotic and manned missions, the utilization of lunar resources has been studied for a long time. In-Situ Resources Utilization (ISRU) refers to the generation of materials (for construction, life support, or as propellants) from the available resources on a celestial body that otherwise, would have needed to be brought from Earth, The authors acknowledge financial support from the Spanish Ministry (PGC2018-097374-B-I00).

Analogues have been developed and characterised for both interplanetary dust and meteoric smoke particles. These include amorphous materials with elemental compositions similar to the olivine mineral solid solution series, a variety of iron oxides, undifferentiated meteorites (chondrites) and minerals which can be considered good terrestrial proxies to some phases present in meteorites. The products have been subjected to a suite of analytical techniques to demonstrate their suitability as analogues for the target materials.

Talk delivered in 14th Europlante Science Congress in Germany, 21 September 2020 - 09 October 2020, The visual observation of meteors has gathered over the last century the interest of scientists and the fascination of public. As the meteor observational techniques were spread worldwide, the meteor research community was avid of reliable mathematical relationships to derive further clues on these events: their orbital origin, their hazardous potential, etc. For such purpose, the combination of the meteor event observed flight parameters seemed to comply with these goals. Moreover, this approach was little by little more feasible given the technology growth that gradually improved the accuracy of the observations. Amongst all the suggested flight parameter relationships available in the literature, the one introduced by Ceplecha and McCrosky [1] in the mid 70¿s became timely and used in many studies as a `ground truth¿. The empirical work of Ceplecha and McCrosky [1] was also mathematically supported by the single body Newtonian formulation that is still widely used to model the meteor trajectory. Moreover, Ceplecha and McCrosky expanded the use of this relationship to elaborate a meteor classification. The classification relies on the value of a criterion, called PE, which ranks the value of the correlation given by the parameters included in the relationship. Although the authors did not expect the classification to be extremely accurate, it allows quick interpretation of the event under study. Consequently, both the criterion and the classification have played a relevant role in the scientific publication over the decades.

Meteoroids impacting the Earth atmosphere are commonly classified using the PE criterion. This criterion was introduced to support the identification of the fireball type by empirically linking its orbital origin and composition characteristics. Additionally, it is used as an indicator of the meteoroid tensile strength and its ability to penetrate the atmosphere. However, the level of classification accuracy of the PE criterion depends on the ability to constrain the value of the input data, retrieved from the fireball observation, required to derive the PE value. To overcome these uncertainties and achieve a greater classification detail we propose a new formulation using scaling laws and dimensionless variables that groups all the input variables into two parameters that are directly obtained from the fireball observations. These two parameters, ${\alpha}$ and ${\beta}$, represent the drag and the mass loss rates along the luminous part of the trajectory, respectively, and are linked to the shape, strength, ablation efficiency, mineralogical nature of the projectile, and duration of the fireball. Thus, the new formulation relies on a physical basis. This work shows the mathematical equivalence between the PE criterion and the logarithm of $2{\alpha}{\beta}$ under the same PE-criterion assumptions. We demonstrate that $log(2{\alpha}{\beta})$ offers a more general formulation which does not require any preliminary constraint on the meteor flight scenario and discuss the suitability of the new formulation for expanding the classification beyond fully disintegrating fireballs to larger impactors including meteorite-dropping fireballs. The reliability of the new formulation is validated using the Prairie Network meteor observations., Comment: 15 pages, 2 figures, 1 table

Lunar meteorites constitute direct, varied samples of the materials forming the lunar surface, allowing to study its bulk chemistry, mineralogy and even geological history. The study of these meteorites not only sheds light on the composition of the Moon but also on its formation and the origin of the Solar System itself. Nowadays we know that these Lunar rocks are delivered to Earth in relative short timescales after being ejected by the impact of an asteroid or a comet from the lunar surface. So far, no lunar meteorite has ever been associated with a crater, not even has been witnessed to fall on Earth. The atmosphere of the Moon is extremely thin, being unable to decelerate particles that are either impacting or escaping from the Moon. It is due to the impact of these high-velocity projectiles that some lunar rocks can be ejected with a velocity above the escape velocity of the Moon (2.38 km/s) [3]. When a projectile of a certain mass impacts the surface of the Moon excavates an impact crater and releases a mass between 3-4 orders of magnitude higher than the projectile mass [3, 4]. Most of the ejected mass falls near the crater and forms continuous ejecta blankets, while the rest follows an impact trajectory far away from the initial impact, while a small part of the ejecta achieves enough velocity to escape the Moon. Our study focuses on the dynamic evolution of these Lunar rocks once they left our satellite, and their ability to reach the Earth as meteorites., The authors acknowledge financial support from the Spanish Ministry (PGC2018-097374-B-I00, PI:JMTR).

Aims. The existence of asteroid complexes produced by the disruption of these comets suggests that evolved comets could also produce high-strength materials able to survive as meteorites. We chose as an example comet 2P/Encke, one of the largest object of the so-called Taurid complex. We compare the reflectance spectrum of this comet with the laboratory spectra of some Antarctic ungrouped carbonaceous chondrites to investigate whether some of these meteorites could be associated with evolved comets. Methods. We compared the spectral behaviour of 2P/Encke with laboratory spectra of carbonaceous chondrites. Different specimens of the common carbonaceous chondrite groups do not match the overall features and slope of the comet 2P/Encke. By testing anomalous carbonaceous chondrites, we found two meteorites: Meteorite Hills 01017 and Grosvenor Mountains 95551, which could be good proxies for the dark materials that formed this short-period comet. We hypothesise that these two meteorites could be rare surviving samples, either from the Taurid complex or another compositionally similar body. In any case, it is difficult to get rid of the effects of terrestrial weathering in these Antarctic finds, and further studies are needed. A future sample return from the so-called dormant comets could also be useful to establish a ground truth on the materials forming evolved short-period comets. Results. As a natural outcome, we think that identifying good proxies of 2P/Encke-forming materials might have interesting implications for future sample-return missions to evolved, potentially dormant, or extinct comets. Understanding the compositional nature of evolved comets is particularly relevant in the context of the future mitigation of impact hazard from these dark and dangerous projectiles., J.M.T.R. and S.T. acknowledge financial support from the Spanish Ministry (PGC2018-097374-B-I00, PI: JMTR). J.L.L. is grateful to ICREA Academia program and funding from Generalitat de Catalunya (2017 SGR 128). US Antarctic meteorite samples are recovered by the Antarctic Search for Meteorites (ANSMET) program which has been funded by NSF and NASA, and characterized and curated by the Department of Mineral Sciences of the Smithsonian Institution and Astromaterials Acquisition and Curation Office at NASA Johnson Space Center.

(Topical Collection: Cosmic Dust from the Laboratory to the Stars, Edited by Rafael Rodrigo, Jürgen Blum, Hsiang-Wen Hsu, Detlef Koschny, Anny-Chantal Levasseur-Regourd, Jesús Martín-Pintado, Veerle Sterken and Andrew Westphal); International audience; Interplanetary dust particles and meteoroids mostly originate from comets and asteroids. Understanding their distribution in the Solar system, their dynamical behavior and their properties, sheds light on the current state and the dynamical behavior of the Solar system. Dust particles can endanger Earth-orbiting satellites and deep-space probes, and a good understanding of the spatial density and velocity distribution of dust and meteoroids in the Solar system is important for designing proper spacecraft shielding. The study of interplanetary dust and meteoroids provides clues to the formation of the Solar system. Particles having formed 4.5 billion years ago can survive planetary accretion and those that survived until now did not evolve significantly since then. Meteoroids and interplanetary dust can be observed by measuring the intensity and polarization of the zodiacal light, by observing meteors entering the Earth’s atmosphere, by collecting them in the upper atmosphere, polar ices and snow, and by detecting them with in-situ detectors on space probes.

Drolshagen, E., et al., [Context] The luminous efficiency, τ, can be used to compute the pre-Atmospheric masses of meteoroids from corresponding recorded meteor brightnesses. The derivation of the luminous efficiency is non-Trivial and is subject to biases and model assumptions. This has led to greatly varying results in the last decades of studies. [Aims] The present paper aims to investigate how a reduction in various observational biases can be achieved to derive (more) reliable values for the luminous efficiency. [Methods] A total of 281 meteors observed by the Fireball Recovery and InterPlanetary Observation Network (FRIPON) are studied. The luminous efficiencies of the events are computed using an ablation-based model. The relations of τ as a function of the pre-Atmospheric meteoroid velocity, ve, and mass, Me, are studied. Various aspects that could render the method less valid, cause inaccuracies, or bias the results are investigated. On this basis, the best suitable meteors were selected for luminous efficiency computations. [Results] The presented analysis shows the limits of the used method. The most influential characteristics that are necessary for reliable results for the τ computation were identified. We study the dependence of τ on the assumed meteoroid's density, ρ, and include improved ρ-values for objects with identified meteoroid stream association. Based on the discovered individual biases and constraints we create a pre-debiased subset of 54 well-recorded events with a relative velocity change >80%, a final height