The CILBO meteor orbit database

Thomas Albin1,2, Detlef Koschny3,4, Rachel Soja1, Ralf Srama1 and Björn Poppe2

1. Institute of Space Systems, University of Stuttgart, Pfaffenwaldring 29, 70569 Stuttgart, Germany. [email protected], [email protected], [email protected] 2. Medical Radiation Physics, Faculty VI, Carl von Ossietzky University, 26129 Oldenburg, Germany [email protected], [email protected] 3. , ESA/ESTEC, Keplerlaan 1, 2201 AZ Noordwijk ZH, Netherlands [email protected] 4. Chair of Astronautics, Technical Univ. Munich, Boltzmannstraße 15, 85748 Garching, Germany

Abstract

The double-station meteor cameras of the CILBO (Canary Islands Long-Baseline Observatory) observe the same volume in the atmosphere above the islands Tenerife and La Palma. The setup allows a stereoscopic view of meteors that is suitable for meteor orbit determination (Koschny et al. 2013, Koschny et al. 2014). The CILBO system has observed over 15,000 meteors simultaneously since operation began in 2012. The software package 'Meteor Orbit and Trajectory Software' (Koschny & Diaz 2002) was extended by a Monte- Carlo based approach to compute orbital elements and other flight dynamic properties. The results are saved in a database and are used by ESA's Meteor Research Group and collaborating institutes. In this work we present an overview of the database and its content. We give a summary of certain stream detections, the sporadic background and the detected source regions.

Key words. CILBO – double station – meteor – orbit determination - database

References:

Koschny, D. & Diaz del Rio, J., „Meteor Orbit and Trajectory Software (MOTS) - Determining the Position of a Meteor with Respect to the Using Data Collected with the Software MetRec“, WGN, Journal of the International Meteor Organization, 2002, 30, 87-101

Koschny, D.; Bettonvil, F.; Licandro, J.; Luijt, C. v. d.; Mc Auliffe, J.; Smit, H.; Svedhem, H.; de Wit, F.; Witasse, O. & Zender, J., „A double-station meteor camera set-up in the Canary Islands – CILBO“, Geoscientific Instrumentation, Methods and Data Systems, 2013, 2, 339-348

Koschny, D.; Mc Auliffe, J.; Drolshagen, E.; Bettonvil, F.; Licandro, J.; van der Luijt, C.; Ott, T.; Smit, H.; Svedhem, H.; Witasse, O. & Zender, J., „CILBO - Lessons learned from a double-station meteor camera setup in the Canary Islands“, Rault, J.-L. & Roggemans, P., editors, Proceedings of the International Meteor Conference, Giron, France, 18-21 September 2014, IMO, pages 10-15 COLLISION WITH AS ONE OF POSSIBLE MECHANISMS OF COMETARY NUCLEI’ SPLITTING by Guliyev A.S. - The results of the statistical analysis of the dynamic parameters of 114 undergoing to nuclear splitting are presented in the article. The list of the objects contains: splitted in the period of the observation comets; one fragment from each couples; the lost comets with designation D; comets with large-scale formations in the atmosphere. Some aspects of the following hypothesis are studied: disintegration of the comet nuclear happens us results of their collision with streams. For the verification of this hypothesis the position of splitted comet’ orbits relatively to 58 meteor streams from Cook’ catalogue is analyzed. Number (N) of orbital nodes of splitted comets according to the distances 0.001, 0.005, 0.01, 0.05 и 0.1 a.. from each stream is calculated. For the determination of the exceed’ measure of N the special algorithm is developed. It allows to find the expected value and dispersion for these comet nodes. Comparative analysis of the parameter N in 29 cases displays its redundancy. It means one of possibility reasons of disintegration of comet nuclear is their collision with meteoroids in the streams. and Kuiper belts as potential sources of vast number of sporadic meteoroids are tested similarity. According of results of calculations first of them may be considered the most efficient region of the disintegration of the periodic comets.

Probability of coincidental clustering among the orbits of small bodies

T. J. Jopek (1), M. Bronikowska (2) (1) Institute Astronomical Observatory, Faculty of Physics, A.M. University, Poznan,´ Poland, (2) Institute of Geology, A.M. University, Poznan,´ Poland

Introduction searched for clusters or the size of the identified group. It is different for groups of 2, 3 ... members. Of course The major tool for finding clusters among small bodies it depends on the cluster analysis method applied. of the Solar System has been orbit similarity, quanti- We tested the impact of some of these factors. For fied by a function called D-criterion. Finding a very a given size of the orbital sample we have assessed similar orbits among the , comets or mete- probability of random grouping for several groups of oroids always rise a question — whether such simi- different sizes. On the other hand, for a given size of larity is only a chance coincidence? To give answer the identified group we have found how these proba- we need an adequate value of the orbital similarity bilities vary with the size of the orbital samples. threshold (a key parameter of any cluster analysis) cor- Finally, keeping fixed size of the orbital sample and responding to the value of the probability of a chance the size of the group, we have shown that the probabil- similarity between two or more orbits. ity of random grouping can be significantly different Reliability of orbital grouping is quite old problem, for the orbital samples obtained by different observa- first time engaged in [5] and [3]. However, due to limi- tion techniques. tation of the computing power at that time it was rather This result is important, it means that contrary to problematic to accomplish an extensive reliability test quite common practice we should rather not use the of detected groups. So no values of the probabilities values of the orbital similarity thresholds applied by were assigned to the identified pairs or groups of me- someone in earlier study e.g. for searching for streams teor orbits. Afterwards the problem was elaborated among video orbits. For given orbital sample and the more extensively in [1, 2] or more recently in [4]. cluster analysis method one should find the proper val- ues of the orbital similarity threshold for each group of 2,3,4, ... members, severally. Our work

In this study we made use of our earlier experiences References [1] and the approach described in [4]. Both methods [1] Jopek, T.J., Froeschlé Cl., 1997, A&A, 320, 631 are based heavily on the artificial orbital samples. We [2] Jopek T.J. Valsecchi, G. B., Froeschlé Cl., 2003, have shown that both methods give consistent results MNRAS, 344, 665 but the method proposed in [4] needs more computing [3] Nilsson C.S., 1964, Aust. J. Phys., 17, 205 power. [4] Pauls A., Gladman B., 2005, M&PS, 40, 1241 Sets of the synthetic meteoroid’s or asteroid’s orbits [5] Southworth R.B., Hawkins G.S., 1963, Smiths. one can generate in different ways: Contr. Astroph.,7, 261 • using different statistical properties of the orbital elements generated randomly, • by taking (or not) into account correlation be- tween some orbital elements. We have investigated how such different methods im- pact assessment of the probability of pairing or group- ing among the orbits? Probability of random grouping depends on sev- eral other factors like the size of the orbital sample Impact detections of temporarily captured natural satellites David L. Clark1,2,3, Pavel Spurný4, Paul Wiegert2,3, Peter Brown2,3, Jiří Borovička4, Ed Tagliaferri5, Lukáš Shrbený4 1 Department of Earth Sciences, University of Western Ontario, London, ON N6A 5B8, Canada 2 Department of Physics and Astronomy, University of Western Ontario, London, ON N6A 5B8, Canada 3 Centre for Planetary Science and Exploration, University of Western Ontario, London, Ontario N6A 5B8, Canada 4 Astronomical Institute, Academy of Sciences of the Czech Republic, CZ-251 65 Ondřejov, Czech Republic. 5 ET Space Systems, 5990 Worth Way, Camarillo, California 93012, USA

Abstract: Temporarily Captured Orbiters (TCOs) are Near-Earth Objects (NEOs) which make a few orbits of Earth before returning to heliocentric orbits. Only one TCO has been observed to date, 2006 RH120, captured by Earth for one year before escaping. Detailed modeling predicts capture should occur from the NEO population predominantly through the Sun-Earth L1 and L2 points, with 1% of TCOs impacting Earth and approximately 0.1% of meteoroids being TCOs. Although thousands of meteoroid orbits have been measured, none until now have conclusively exhibited TCO behaviour, largely due to difficulties in measuring initial meteoroid speed with sufficient precision. We report on a precise meteor observation of January 13, 2014 by a new generation of all-sky fireball digital camera systems operated in the Czech Republic as part of the European Fireball Network, providing the lowest natural object entry speed observed in decades long monitoring by networks world-wide. Modeling atmospheric deceleration and fragmentation yields an initial of ~5 kg and diameter of 15 cm, with a maximum Earth- relative velocity just over 11.0 km/s. Spectral observations prove its natural origin. Back- integration across observational uncertainties yields a 92 - 98% probability of TCO behaviour, with close lunar dynamical interaction. The capture duration varies across observational uncertainties from 48 days to 5+ years. We also report on two low-speed impacts recorded by US Government sensors, and we examine Prairie Network event PN39078 from 1965 having an extremely low entry speed of 10.9 km/s. In these cases uncertainties in measurement and origin make TCO designation uncertain.

[1]

Hypervelocity Impact Plasma Measurements and Simulations

S. Close (1), N. Lee (1), A. Fletcher (2), A. Goel (3), A. Nuttall (1), M. Hew (1), P. Tarantino (1), I. Linscott (1) (1) Stanford University (2) Massachusetts Institute of Technology (3) California Institute of Technology

Hypervelocity micro particles, including impacts. This velocity threshold is also where meteoroids and with < 1 ng, the plasma transitions from partly to fully routinely impact spacecraft. Upon impact, a ionized. hypervelocity particle, defined as a particle with a speed greater than the speed of sound in the material (~5–10 km/s), produces plasma with a density that is approximately that of the solid material (>1027 m-3). The temperature is relatively cool and thus the plasma is considered non-ideal. Because of the strong pressure gradient relative to the background vacuum, the plasma expands at approximately the isothermal sound speed. During this process the density drops and the plasma transition from non-ideal to ideal and collisional to collisionless. This plasma, with a charge separation commensurate Figure 1. Radio frequency emission for high with different species mobilities, can produce a and low velocity meteoroid impacts on a strong electromagnetic pulse (EMP) with a broad biased impact target. This plot shows accumulated/normalized RF power density for frequency spectrum. Subsequent plasma [X] total impact events (in red), and oscillations resulting from instabilities can also emit partitioned into the power density contributed significant power and may be responsible for many by impacts above and below 20 km/s (in blue reported satellite anomalies. and red, respectively)

We present theory and recent results from ground- based impact tests aimed at characterizing hypervelocity impact plasma. We also show results from particle-in-cell (PIC) and computational fluid dynamics (CFD) simulations that allow us to extrapolate to regimes not currently possible with ground-based technology in order to predict the effect of meteoroid impacts on spacecraft. We show that significant impact-produced radio frequency (RF) emissions occurred in frequencies ranging from VHF through L-band and that these emissions were highly correlated with fast (>20 km/s) impacts that produced a fully ionized plasma.

Figure 1 shows representative radio frequency data at 315 MHz and 916 MHz collected using patch antennas at the Max Planck Van de Graaff accelerator in 2011. These data demonstrate a dependence on the emission strength and characteristics as a function of impact velocity. In particular, impactors with high velocity (>20 km/s) demonstrate a strong emission at 916 MHz that is not detected for lower velocity Commissioning the Desert Fireball Network data pipeline

H.A.R. Devillepoix (1,2), P.A. Bland (1), M.C. Towner (1), M. Cupák (1), E.K. Sansom (1), R.M. Howie (3), M. Cox (1), T. Jansen-Sturgeon (1), J. Paxman (3) (1) Dept. Applied Geololgy, Curtin Univ., (2) International Centre for Radio Astronomy Research (ICRAR), (3) Dept. Mechnical Engineering, Curtin Univ., ([email protected])

Introduction Triangulation of the trajectory is currently done us- ing modified least squares minimisation approach, the The Desert Fireball Network (DFN) is triangulating next iteration will use simulations based on bright over an area of more than 1.5 million km2. flight dynamics. Thanks to this large sampling area and comparatively Using data from the top end of the trajectory, soft- clear skies in the Australian outback, the DFN is able ware was written to propagate the orbit of the me- to observe a significant number of fireballs, some of teoroid back in the solar system. On the bottom which have the potential for a recovery. end, each fragment can be isolated thanks to the high resolution of the images, and finally traced down to With a rate of data acquisition exceeding 60 the ground using Weather Research and Forecasting TB/month, reducing every fireball requires an auto- (WRF) wind models for dark flight integration. mated data pipeline. Although a completely auto- At every step, control routines automatically assess mated pipeline is not needed for meteorite falls calcu- the quality of the data, flagging any problems and un- lations, the by-product dataset contains invaluable in- usually large uncertainties. formation about the distribution of meter-sized NEAs [1]. The reduction of the entire dataset is the only way to close the statistical gap between telescope/radar ob- positions servations of larger asteroids, and dust-size particles observed by meteor networks. From final masses calculated based on dynamic flight modelling [3], 12 events have been identified for me- teorite searching (criteria from [4]). One of them has Reduction data pipeline already been recovered on December 31 2015 on dried salt lake Eyre. The 49 Automated Desert Fireball Observatories col- lectively take ∼40,000 still images every night. Orbital dynamics New approaches have been developed to make the data pipeline as automated as possible. The current dataset contains 2 fireballs from the re- Neural network algorithms are used to detect mete- cently identified shower Volantids [5], and 7 ors in the images. locally on the cameras, to minimise fireballs. The 2015 data also shows a large number of network usage. fireballs (37), which seems to confirm the pre- A unique code is embedded in each fireball trajec- diction in [4]. tory by the use of a shutter system modulated with a DeBrujin sequence (patent pending [2]). This provides absolute as well as relative timing for the meteoroid References trajectory. Decoding this sequence is currently the last [1] Brown, P. et al., Icarus, 96-111, March 2016 step that requires human eye checking. [2] Howie, R. et al., Australian Patent: 2016900714, Astrometric calibration of the images can be done issued date Feb. 26, 2016 blindly: no prior knowledge of the optics used nor [3] Sansom, E. et al., MAPS, vol. 50, 1423-1435, pointing information is required, the stars present in 2015 [4] Brown, P. et al., MAPS, vol. 48, 270-288, 2013 the image are enough to build a reference system pre- [5] Jenniskens, P. et al., in preparation cise down to 1 arcminute. A Monte Carlo type simulation toolbox for solar system small body dynamics

Daniel Kastinen, Johan Kero Swedish Institute of Space Physics (IRF), Box 812, SE-98128 Kiruna, Sweden ([email protected])

Introduction particles is displayed as a function of solar longitude and particle mass. The ejected mass distribution was The dynamics of small bodies in the solar system form logarithmically uniform. In addition, we have used a theoretical basis to study meteoroid streams and their cluster analysis and time tracing of meteoroid streams connected meteor showers. The perhaps most missed to compare several orbital similarity functions, the so- feature in current models is the ability to easily con- called D-criteria and previously untested natural met- nect programs with different functionalities. We be- rics [2]. lieve this is the main reason why many contemporary techniques such as Monte Carlo simulations of me- teoroid streams, orbital stability analysis, and so on, have not yet been combined. We have thus started de- velopment of a toolbox able to showcase the power of a software capable of these actions. The software is designed in a modular fashion, where one master program has the ability to call several independent modules. The parent bodies can be hand-picked, or Figure 1: Simulation of the 2011 October . generated from probability distributions like the Pan- STARRS Synthetic Solar System Model. This enables a wide re-use of the tools developed. To study mass propagation we use the toolbox in a statistical man- ner propagating a distribution of possibilities rather than relying on single assumptions. The distributions currently implemented represent orbital elements, sub- limation distance, density, size, and surface activity. The software integrate ejected particles and examines close encounters with the Earth.

Results

Simulations include perturbations from all major plan- Figure 2: Simulation of the 2011 October Draconids ets, radiation pressure, and the Poynting–Robertson mass flux propagation efficiency. effect. Validations of the software was done by simu- lating a known and observed , the 2011 October Draconids [1]. The simulation was performed by ejecting material from comet 21P/Giacobini-Zinner References between 1866 and 1907 and propagating the material [1] Kero, J., Fujiwara, Y., Abo, M., Szasz, C and until 2020. The results of the prediction is shown in Nakamura, T. MNRAS, 424:1799-1806, 2012. Fig. 1. To further demonstrate the statistical approach, [2] Kholshevnikov, K. V. and Vassiliev, N. N., Ce- several probabilistic results using this validation run lestial Mechanics and Dynamical Astronomy, has been calculated. One example is shown in Fig 2 89:119-125, 2004. where the most probable encounter rate of simulated Evidence of Eta Aquariid Outbursts Recorded in the Classic Maya Hieroglyphic Script Using Orbital Integrations

J.H. Kinsman (1), D.J. Asher (2) (1) Independent researcher, Atlanta, Georgia, USA ([email protected]), (2) Armagh Observatory, College Hill, Armagh BT61 9DG, UK ([email protected])

Presently there is no firm evidence that the ancient were likely noted in the ancient script. Most of these Maya civilization recorded specific dates of meteor outbursts were due to recent (within a few centuries) showers or outbursts in the corpus of Maya hiero- revolutions of Comet Halley, however a few were possi- glyphic inscriptions [1]. Although many of the over bly due to resonant behavior found in some of the older 2,000 dates record rulers’ births, accessions to kingship (of the order of a thousand years) Halley trails. and deaths, many inscriptions remain vague or untrans- lated and thus provide an opportunity for new inter- pretations. Given that a majority of the ancient Maya References dates occur in the Classic Period, AD 250–909, the [1] Trenary, C., Archaeoastronomy Vol. X, pp. 99- authors decided to investigate Eta Aquariid outbursts 116, 1987-1988. since the orbit of parent Comet 1P/Halley is well known [2] Yeomans D. K. and Kiang T., Mon. Not. R. As- [2] and came closest (post-perihelion) to Earth’s orbit tron. Soc., Vol. 197, pp. 633-646, 1981. around AD 500; the Eta Aquariid shower corresponds [3] Sato, M. and Watanabe, J., Proc. Meteoroids to the post-perihelion encounter of the Halley mete- 2013, ed. Jopek, T. J. et al., A. M. Univ. Press, oroid stream with Earth. In contrast, the comet’s orbit pp. 213-216, 2014. (pre-perihelion) was at a greater distance from Earth’s [4] Everhart, E., Dynamics of Comets: Their Origin orbit during the same period (the Orionid shower cor- and Evolution, ed. Carusi, A. and Valsecchi G. B., responding to the pre-perihelion encounter). Further- Reidel, pp. 185-202, 1985. more, recent orbital analysis by Sato and Watanabe con- [5] Chambers, J. E., Mon. Not. R. Astron. Soc., Vol. firmed that enhanced activity of the Eta in 304, pp. 793-799, 1999. 2013 was due to dust trails produced by Halley in 1198 BC and 911 BC [3]. By investigating the stream clos- est to Earth’s orbit the authors surmised that chances would be greatest for outbursts due to recent revolutions of Comet Halley. The ancient Maya area covers the northern latitudes from about 14◦ to 21.5◦ N and western longitudes from about 87◦ to 93◦ W, including the modern Central American countries of eastern Mexico, Guatemala, Be- lize, El Salvador and western Honduras. Although the are considered primarily a southern lati- tude shower, the would have been visible to the Maya in the east for more than three before morn- ing twilight. Lacking recorded radiant information, by comparing the date and time of any modeled outbursts to events recorded on or near that date in the inscrip- tions, a reasonable decision could be made on the likely correspondence of an event to a meteor outburst. Using the RADAU algorithm [4] as implemented in the MERCURY integrator package [5], the authors nu- merically integrated meteoroid-sized particles released by Comet Halley in 1404 BC and later, under the in- fluence of planetary pertubations and solar radiation pressure, concluding that several Eta Aquariid outbursts The distribution of meteor substance in the Galactic coordinate system according to the radar database and SonotoCo's TV catalogue

S. Kolomiyets Kharkiv National University of Radio Electronics, Kharkiv, Ukraine ([email protected])

We used different criteria to cut the data and to choice Introduction samples, e.g.: 0.9< e <1; 1.0 < e <1.1; Q <1.15 AU; Q>50 AU; 1.15 < Q < 5 AU; 5 46 km/s (Fig.2). Hyperbolic meteors may be associated with the "extrasolar" space. In this case the properties of the "extrasolar" movement may be occurred in the orbital parameters of the Earth meteors. Some of the observations are bearing out that idea. There are two large databases of meteoroids’ orbital elements: MARS radar one obtained during 1972-1978 (Ukraine) [1-2] and SonotoCo's TV catalogue [3-4] obtained during 2007-2013 (Japan). Purpose of the research: search "extrasolar" sources of meteor substance in the Earth atmosphere using positions of meteor radiants in the Galactic coordinate system.

Method of analysis, and Results

Coordinates of apexes of the moving Sun in Equatorial and Galactic systems we can see using Table. We accept 0 0 Fig 2 Position of radiants (in b and l, the Galactic coordinate that the Galaxy Apex coordinates equals: l~100 , b ~ -4 . system) of hyperbolic and elliptic (0.9

We can search such coordinates among observed meteor The work was carried out as part of the research work of radiants in the Earth atmosphere (Fig. 1). the Kharkiv National University of Radio Electronics (0114U002697). The author thanks the intern M.Sc. Checha V., which produced a large amount of computation in the processing of databases.

References [1] Kashcheyev, B.L. and Tkachuk, A.A. Materials global data center "B". Results of Radar observations of faint meteors: Cataloque of meteor orbits to +12 m, Moscow, 232 p., 1980. - In Russian. [2] Kolomiyets, S.V. Cataloque of 67 hyperbolic orbits of meteoroids according to archive data of radar observations in Kharkiv, Bulletin astronomical school, Kyiv, Vol.1, N 1-2, p.123-127, 2014. - In Ukrainian. [3] SonotaCo. A meteor shower catalog based on video observations in 2007–2008, WGN, Journal of the IMO, Fig 1 Position of radiants (in b and l, the Galactic Vol. 37, pp. 55-62, 2009. coordinate system) of hyperbolic meteoroids (1

A.V. Moorhead (1), P.G. Brown (2), M.D. Campbell-Brown (2), A. Kingery (3) W.J. Cooke (1) (1) NASA Meteoroid Environment Office, Marshall Space Flight Center, Huntsville, Alabama 35812 (althea.moorhead@.gov), (2) Department of Physics and Astronomy, The University of Western Ontario, London N6A3K7, Canada (3) ERC Inc./Jacobs ESSSA Group, Marshall Space Flight Center, Huntsville, Alabama 35812

The observed meteor speed distribution provides information on the underlying orbital distribution of Earth-intersecting meteoroids. It also affects space- craft risk assessments; faster meteors do greater dam- age to spacecraft surfaces. Although radar meteor net- works have measured the meteor speed distribution numerous times, the shape of the de-biased speed dis- tribution varies widely from study to study. Optical characterizations of the meteoroid speed distribution are fewer in number, and in some cases the original data is no longer available. Finally, the level of uncer- tainty in these speed distributions is rarely addressed. In this work, we present the optical meteor speed distribution extracted from the NASA and SOMN all- sky networks [1, 2] and from the Canadian Automated Meteor Observatory (CAMO) [3]. We also revisit the radar meteor speed distribution observed by the Cana- dian Meteor Orbit Radar (CMOR) [4]. Together, these data span the range of meteoroid sizes that can pose a threat to spacecraft. In all cases, we present our bias corrections and incorporate the uncertainty in these corrections into uncertainties in our de-biased speed distribution. Finally, we compare the optical and radar meteor speed distributions and discuss the implica- tions for meteoroid environment models.

References [1] Cooke, W.J. and Moser, D.E., Proceedings of the IMC, Sibiu, pp. 9-12, 2012. [2] Weryk R.J., Brown, P.G., Domokos, A., Ed- wards, W.N., Krzeminski, Z., Nudds, S.H., and Welch, D.L. Earth, , and Planets, Vol. 102, pp. 241-246, 2008. [3] Weryk, R.J., Campbell-Brown, M.D., Wiegert, P.A., Brown, P.G., Krzeminski, Z., and Musci, R., Icarus, Vol. 225, pp. 614-622, 2013. [4] Brown, P.G, Weryk, R.J., Wong, D.K, and Jones, J, Earth, Moon, and Planets, Vol. 102, pp. 209- 219, 2008. The Toroidal Sporadic Source: Understanding Temporal Variations

P. Pokorny 1, P. Brown 1, A. Moorhead 2, P. Wiegert 1 (1) Department of Physics and Astronomy, University of Western Ontario, London, Ontario, Canada ([email protected]) (2) NASA Meteoroid Environment Office, Marshall Space Flight Center, Huntsville, Alabama 35812, USA

The origin and characteristics of the North toroidal jects which might contribute to the NT meteoroid pop- (NT) sporadic meteoroid source remains poorly ulation at the current time and integrated their orbits known. Though the NT was first noted in radar mea- backward in time 25,000 years. For each potential par- surements in the late 1950s, its origin has puzzled as- ent body, we simulate ∼10 clones to span the range of tronomers for more than 50 years. The NT meteoroid possible parent body orbits as a function of time. From population shows orbital elements dominated by par- our initial 25 ka, we eject 2000 test meteoroids ticles with very high inclinations, modest semi-major per 100 years of sizes 30 µm to 1 mm per potential axis values and low eccentricities unlike any known parent clone and examine the resulting dust trail inter- contemporary parent population in the Solar System. secting the Earth in an attempt to match the various Recently, several dynamical models have suggested temporally distinct portions of the NT meteoroid com- that the parent bodies of the NT source may be linked plex. We find that while some of the observed features to the population of Halley-type comets. However, of the NT can be modeled as distinct past contributions no model to date has been able to reproduce in de- from individual parent bodies (notably 2008 KP, 1973 tail the significant temporal variations in activity seen NA, 2009 WN25, 96P/Machholz, and P/2008 Y12), throughout the year. In this work we will present NT but many major features in the NT source shown no data measured by the Canadian Meteor Orbit Radar correspondence with known parent bodies or their po- (CMOR) between 2011–2014, which we use to define tential clones. We will discuss a best estimate for the in detail the temporal and orbital element variations age of observed NT features and discuss several can- in NT activity which a model must reproduce. In this didate parent bodies that are able to reproduce some first model, we have identified over 150 near-Earth ob- sub-structure in the NT source.

Figure 1: Average flux of the north toroidal source measured by CMOR during 2011-2014. Gray boxes represent the duration of known NT showers where their three letter IAU designations are positioned an the peak of their flux. An overview of the CILBO spectral observation program.

R. Rudawska (1), J. Vaubaillon (2), J. Toth (3) (1) ESA/ESTEC, Nordwijk, the Netherlands, (2) IMCCE - Observatoire de Paris, Paris, France, (3) Comenius University, FMPH, Bratislava, Slovakia ([email protected])

A concerted effort is underway to identify the parent References bodies of Earth's meteor showers [1]. Several now dormant comets have been identified as the parent bodies [1] Jenniskens, P., Meteor Showers and their Parent of the (2003 EH1), the Comets (Cambridge University Press), 2006 (2002 EX12) and the (2008 ED69). In [2] Jenniskens, P., Gural, P. S., Dynneson, L., et al., order to find more such associations, ongoing work is Icarus, 216, p. 40, 2011 focused on improving the meteor shower observations [2, [3] Jewitt, D.,, The Astronomical Journal, 143, p. 66, 2012 6, 11, 12] and create new research tools for meteor shower [4] Jewitt, D. and Li, J., The Astronomical Journal, 140, identification [5, 7, 8, 9]. p. 1519, 2010 [5] Jopek, T. J., Rudawska, R., & Bartczak, P. , Earth At the same time, however, automated surveys of Near- Moon and Planets, 102, p. 73, 2008 Earth Objects (NEOs) continue to discover objects in [6] Koschny, D., McAuliffe, J., Bettonvil, F., et al., in cometary-like orbits (2 < T < 3) that are likely candidate Proceedings of the International Meteor Conference, parent bodies [10]. Some of them unexpectedly produce a Poznan, Poland, 22-25 August 2013, pp. 166-167, 2014 comet-like comae and tails [3, 4]. Here, we study one such [7] Rudawska, R. and Jopek, T. J., in IAU Symposium, case, that of asteroid 2016 BA14 recently discovered by Vol. 263, IAU Symposium, pp. 253-256, 2010 the Pan-STARRS survey, which shows cometary [8] Rudawska, R., Vaubaillon, J., and Atreya, P., Astron- appearance and has a Tisserand parameter of 2.8. omy and Astrophysics, 541, A2, 2012 Moreover, it was pointed that the orbital similarly between [9] Rudawska, R., Matlovic, P., Toth, J., and Kornoˇs, L., P/2016 BA14 and comet 252P/LINEAR. If those Planetary and Space Science, 118, p. 38, 2015 Family Comets split in the past, significant dust would [10] Rudawska, R. and Vaubaillon, J., Planetary and Space have been released. Typically, half the comet's mass is lost Science, 118, p. 25, 2015 in such fragmentations [1]. If P/2016 BA14 and [11] SonotaCo, WGN, Journal of the International Meteor 252P/LINEAR are the remaining objects after such Organization, 37, p. 55, 2009 fragmentation, they are relatively large objects with a [12] Toth, J., Zigo, P., Kalmancok, D., et al., in diameter of about 1~km. Proceedings of the International Meteor Conference Mistelbach, Austria, 27-30 August 2015, pp. 63–65, 2015 In our talk, we will present a survey of results dealing [13] Vaubaillon, J., Colas, F. Jorda, L., Astronomy and with investigating association of the comets P/2016 BA14 Astrophysics, 439, p. 751, 2005 and 252P/LINEAR with meteor showers observed on Earth. We carry out a further search to investigate the possible genetic relationship between comets themselves as well. To confirm the reality of relation between a comet and meteoroid stream it is necessary to investigate the evolution of their orbits. The model of generation and evolution of meteoroid stream in the solar system is taken from Vaubaillon et al. [13]. The objects’ orbital elements and physical properties are taken from JPL horizons website. The ejections of meteoroids from the possible parent body surface took place when it was passing its perihelion between 1800 A.D. and 2016 A.D. Next, the orbits of ejected meteoroids were integrated to year 2079. Evidence of Three Body Resonance in Meteoroid Streams

A. Sekhar (1, 2), D. J. Asher (2), J. Vaubaillon (3), M. Hajduková (4), J. Tóth (5), R. Rudawska (6), R. Soja (7) (1) Centre for Earth Evolution and Dynamics, University of Oslo, Norway ([email protected]), (2) Armagh Observatory, United Kingdom (3) IMCCE, Paris Observatory, France (4) Astronomical Institute, Slovak Academy of Sciences, Slovakia (5) Comenius University, Slovakia (6) ESA/ESTEC, Netherlands (7) University of Stuttgart, Germany

Introduction planned in this direction so that meteor observers can be alerted. Real observation of an enhanced meteor There have been various examples of two body mean activity from this unique three body resonance mech- motion resonances (MMR), [1][2][3][4][5][6], in dif- anism would help to compare with well observed me- ferent meteoroid streams. Many of these Jovian two teor outbursts from known two body MMRs in the body MMRs are known to have caused observed me- past. Linking the theoretical predictions with real teor outbursts and storms on Earth in the past and observations,[15][16], would help to gain more insight have been widely reported and studied,[7][8][9][10], into the dynamics of three body MMR in stream struc- although enhanced activity from two body MMRs in- tures which have not been explored before. volving other planets has not been directly observed so far. Nevertheless there are previous works explor- ing them theoretically, especially the ones related to References Saturnian MMR,[11][12], and Uranian MMR,[13], in [1] Asher D. J., Bailey M. E., Emel’yanenko V. V., meteoroid streams. However the occurrence of three 1999, MNRAS, 304, L53. body MMR in real solar system bodies is a much rarer [2] Jenniskens P., Meteor Showers and their Par- phenomenon although there are many resonant sweet ent Comets. Cambridge Univ. Press, Cambridge, spots in the solar system in an abstract mathematical 2006. sense. The first example of real solar system bodies [3] Ryabova G. O., 2012, MNRAS, 423, 2254. [4] Vaubaillon J., Lamy, P., Jorda, L., 2006, MN- showing three body MMR is the Laplacian resonance RAS, 370, 1841. involving the Galilean satellites, namely Ganymede, [5] Soja R. H., Baggaley W. J., Brown P., Hamilton Io and Europa,[14]. In this work, we find the first dy- D. P., 2011, MNRAS, 414, 1059. namical evidence of a three body MMR in the context [6] Sekhar A., Asher D. J., 2014, Meteorit. Planet. of meteoroid streams. Sci., 49, 52. [7] McNaught R. H., Asher D. J., 1999, WGN (J. Stream Dynamics IMO), 27, 85. [8] Rendtel J., 2007, WGN (J. IMO), 35, 41. The existence of three body resonant structures in the [9] Sato M., Watanabe J., 2007, PASJ, 59, L21. Perseid stream is confirmed from our integration study. [10] Christou A. A., Vaubaillon J., Withers P., 2008, The configuration is close to 1:4:10 MMR for orbital Earth Moon Plan., 102, 125. periods of Perseid particle, Saturn and Jupiter respec- [11] Brown P., 1999, PhD thesis, Univ. Western On- tively. Typically these meteoroid particles get trapped tario. in this three body resonance for about 2 kyr. The sim- [12] Sekhar A., Asher D. J., 2013, MNRAS, 433, ulations were able to establish the effectiveness of this L84. [13] Williams I. P., 1997, MNRAS, 292, L37. resonance in retaining compact dust trails for a long [14] Laplace P. S., 1799, Mécanique Céleste by the time, in contrast to the wider scattering of the non- Marquis de Laplace. By Nathaniel Bowditch. resonant particles in the orbit phase space. Translated with a commentary, 4 Vols. (Boston, Linking Theory and Observations 1829-1839). [15] Rudawska, R., Vaubaillon, J., Atreya, P. 2012, This resonant property in turn indicates that one could A&A, 541, 5. [16] Hajduková, M., Rudawska, R., Kornos, L., Tóth, expect intense meteor activity on Earth in future from J. 2015, P&SS, 118, 28. this newly found resonance. Further predictions are Meteoroid impact detections by the Gaia spacecraft at L2

E. Serpell, D. Milligan, J. Marie, P. Collins European Space Operations Center, Darmstadt, Germany

Abstract

Gaia is the European Space Agency's cornerstone mission to measure the positions of a billion stars in our galaxy with unprecedented precision. In operational orbit at the second Sun-Earth Lagrange point (L2) 1.5 million km from the Earth since early 2014 Gaia has been exposed to a flux of high velocity impacts from micrometeoroids. These almost daily events are a known hazard of the space environment and Gaia is able to operate in these conditions without degradation to its primary function. When a meteoroid particle strikes Gaia it transfers enough energy to disturb the spacecraft attitude and at the same time cause local heating and deformation of the spacecraft structure. Because of the demanding requirements of the primary mission the spacecraft is equipped with extremely accurate on-board sensors for attitude and rate determination that are recording the frequent disturbances due to meteoroid impact events. This paper presents the analysis of several micrometeoroid impacts on the spacecraft sun-shield where it has been possible to determine the energy and direction of the impactor. Because of the extremely stable thermal environment at L2 it has also been possible to observe the small localised changes to the spacecraft thermal balance caused by deformation due to these events. For a subset of these impacting particles the probable parent body has been identified by correlating the direction of the impactor with the radiants of known meteoroid streams. In comparison to low Earth orbit which is contaminated with man made debris the environment at L2 is a pristine environment for meteoroid research and Gaia is providing a valuable insight into this environment. Collisional implementation for an interplanetary dust model

R. H. Soja (1), G. Schwarzkopf (1), J. Vaubaillon (2), T. Albin (1,3), J. Rodmann (4), N. Skuppin (1), W. Alias (1), M. Sommer (1), E. Grün (5), R. Srama (1) (1) Institute of Space Systems, University of Stuttgart, Pfaffenwaldring 29, 70569 Stuttgart, Germany, ([email protected]) (2) IMCEE, 77 Avenue Denfert Rochereau, 75014 Paris, France (3) Universitätssternwarte Oldenburg, Institute of Physics and Department of Medical Physics and Acoustics, Carl von Ossietzky University, 26129 Oldenburg, Germany, (4) University of Göttingen, Institute for Astrophysics, 37077 Göttingen, Germany, (5) Max Planck Institute for Nuclear Physics (MPIK), Saupfercheckweg 1, 69117 Heidelberg, Germany)

The Enhanced Interplanetary Meteoroid Popu- References lation Model is an ESA funded project to develop a model of the interplanetary background dust for [1] Dikarev, V., Grün, E., Baggaley, J., Galligan, D., spacecraft impact hazard studies. This is envisaged Landgraf,M., Jehn, R., The New ESA Meteoroid as an improvement of the current ESA Interplanetary Model., Adv. Space Res., 35, 1282–1289, 2005. Meteoroid Environment Model (IMEM) [1]. This [2] Grün, E., Sram, R., Horanyi, M., Kr¨uger, H., existing model is is constrained by various in-situ and Soja, R., Sterken, V., Sternovsky, Z., and Strub, infrared observations, but several simplifications in P. Comparative analysis of the ESA and NASA the implementation, including a step function for the interplanetary meteoroid environment model. In long term behaviour of particles of different masses, L. Ouwehand, editor, Proceedings of the 6th Eu- mean that it is unable to provide a full interpretation ropean Conference on Space Debris, 22-25 April of the background cloud [2]. 2013, ESA/ESOC Darmstadt, Germany, August 2013. [3] Grün, E., Zook, H. A., Fechtig, H., and Giese R. The new model will include dynamical evolution H. Collisional balance of the meteoritic complex. over several 100000 years of cometary and asteroidal Icarus, 62: 244–272, May 1985. dust populations of particles with sizes 10 µm – 1 cm in the inner solar system, including a colli- sional model as well as standard gravitational and radiation forces. Here we describe initial activi- ties for the project, including description of initial populations, and the expected next steps for the model.

In particular, we describe the development of a collisional destruction model, based on the work of Grün et. al (1985) [3], in order to provide collisional lifetimes encompass the dynamical history of different types of particles. We use existing background model given by IMEM to provide the impactor population, and trace how the collisional lifetime varies each orbit, as the particles undergo orbital variations due to perturbations and Poynting-Robertson drag.

Acknowledgements

This work is funded under ESA contract 4000114513/15/NL/HK. Title: A confidence index for the forecasting of the meteor showers

Author: Jeremie Vaubaillon - IMCCE - 77 Av Denfert Rochereau 75014 Paris, France

Abstract: Since the work of McNaught & Asher (1999) the forecasting of the meteor showers are made possible with several degrees of confidence. When the shower is caused by an isolated well identified trail ejected by a well known comet from which the orbit is well known, the results are amazingly accurate in terms of timing. The level of the shower is still today a challenge and is partly linked to our ignorance of the activity of the comets in the past. The forecasting of meteor showers is less accurate for poorly known comets, or previously unobserved encounter between a planet and a specific trail. In this work, an index is created to provide astronomers with an idea of how the forecasting were performed and as a consequence, how confident one can be regrading the results. Observation plan for Martian meteors by Mars-orbiting MMX spacecraft

M.-Y. Yamamoto (1), MMX WAM/WAMS team (1) Kochi University of Technology, Kami, Japan ([email protected])

using an empirical function between the dust particle Introduction density and the distance from the Sun. However, such dataset is extremely limited for the outer space in spite of In 2015, the “Martian Explorer (MMX)” mission the Earth orbit. In 1997, for discussing an opportunity for plan is selected as the next Japanese middle scale space European Martian explorer, a Martian meteor camera was mission by JAXA. Targets of the spacecraft are focused on designed [1]. Since the basic parameters are not Martian moons (Phobos and Deimos). The main mission significantly changed for Martian meteor environment, the is sample-return of surface materials on one of the Martian case study could be imported into the MMX scientific moons like and Hayabusa-2, however, when consideration. The observation plan defined if we can put staying on the Mars-orbiting stage on the exploration, the a high-sensitivity camera with capturing +4.5 magnitude spacecraft would have enough time to take many images or darker meteors, 1 meteor per 30 minutes can averagely from the orbit not only to the targeting Martian moons but be realized if the FOV of 40 degrees is appropriately also Martian surface. If we have a high-sensitivity camera selected for the dark side of Mars seen from about the aboard the MMX spacecraft, the first statistical study on Phobos orbit. As for the meteor shower prediction, several the Martian meteors might be realized. works have been carried out for encountering simulation between known periodic comets and Mars. For example, during 2021 for MMX arrival, the following Martian MMX mission meteor shower is predicted by numerical calculations [2]. - Feb. 9: 13P_Olbers - May 5: 49P_Arend-Rigaux The MMX mission has been discussed by special team - Jul. 30: 81P_Wild2 - Aug. 9: 144P_Kushida and working groups in Japan deeply collaborating with the - Aug. 14: C_1854L1_Klinkerfues -Oct. 29: 2007H2 society of planetary science in Japan as well as in JAXA - Nov. 10: Pi-Puppids - Dec. 23: 9P_Tempel1 HQ. At a timing of the Announcement of Opportunity If we can operate high-sensitivity camera in the meteor (AO) calling for the next middle scale space mission in shower periods as well as not in the shower periods for 2015, the MMX mission plan was selected and announced comparison, existence of the Martian meteor showers can to the public in June 2015. After the selection, many kinds be statistically proven. Light curve and spectrum study of discussions for science targets as well as onboard might be interested but it depends on the instruments instruments with specifications were rapidly and deeply equipped with the MMX. discussed by many teams including foreign scientists. The AO for MMX onboard instruments and suites was held in February 2016, and currently in the selection process as of Summary March 1. The exploration orbit plan for the MMX spacecraft surely includes Mars-orbiting phase for a while The next Japanese Mars explorer MMX is introduced with for ensuring the multiple encounters for Phobos and discussing about the possibility of observing Martian Deimos. The period of parking on the Mars-orbiting is meteors for monitoring the dark side of Mars from the currently discussed by the mission design team in JAXA, Mars-orbiting spacecraft at the altitude of several however, it will be fixed for a year or more, thus the thousands of km from the Martian surface. If we can period could be a significant opportunity for making install a high-sensitivity camera on the MMX spacecraft special observation not only for the Martian moons but and operating it for a long time during the Mars-orbiting also for Mars itself. For the meteor/meteoroids study, if phase, the statistical study on the Martian meteor and we could focus on the dark side of Mars, the first meteor showers could be realized. Though it is still in the statistical study on the Martian meteors might be realized discussing phase for the engineering model of the during the Martian stay of the MMX spacecraft. The instrumentations for the MMX, the discussion on this significant aspect is if the sample-return from the Mars- Meteoroids 2016 conference will be significant for the orbiting mission were realized, high-quality datasets feedback from the international meteor/meteoroids society including GB or TB scale movies could be obtained with to the MMX mission. the memory cards within the capsule instead of the extremely limited narrow-band space data link from the MMX to the Earth. References [1] Koschny, D., et al., MIOS-Meteor and Impact Meteors at Mars orbit Observations from Space on Mars, A proposal for the ESA Mars Express mission orbiter payload, 1998. Meteors at Mars orbit has been studied theoretically by [2] Vauvaillon, J., private comm. Towards a theoretical determination of the geographical probability distribution of meteoroid impacts on Earth

Jorge I. Zuluaga, Mario Sucerquia Solar, Earth and Planetary Physics Group (SEAP), Aerospace Science and Technology Research (ASTRA), Institute of Physics, Universidad de Antioquia Medellín, Colombia, [email protected], [email protected].

Introduction Methods Earth’s surface has been impacted by asteroids and We have adapted well known techniques used in meteoroids during the last couple of Giga years. The numerical optics and scientific visualization, namely “ray number of impacts has disminished, but still lots of tracing” or “ray casting” [3]. Our adapted technique, potential hazardous asteroids and undetected meteoroids called “gravitational ray tracing” (GRT) studies the are threating our now overpopulated planet. The capture and colision of these bodies could be enhanced by the propagation of meteoroids (analogues to photons) from complex combined gravitational field generated of the Earth back to their asymptotic place in configuration Earth - Moon system [1]. Are impacts randomly space (analogues to light sources). The distribution of distributed on the surface of the Earth? The largest already discovered asteroids (Fig.1) provide us the impacts witnessed by modern humans, Tunguska and properties of the sources and allows us a way to assign Chelyabinsk events, happen just ~3,000 km away. The probabilities to impact places. In GRT we use methods “Campos del Cielo” in Argentina and tektites fields in Chile and Colombia, possibly hints to a link between familiar to the original “ray casting” including, for different impact events. Since the distribution of asteroids example the methods for generating initial conditions in the Solar System is not random it is natural to think that (Fig. 2). impacts will also be clustered on the Earth (following for example the ); however, relative Earth-asteroid velocity and the complex dynamics of the earth moon system may modify this natural expectation [2]. Several authors have studied the geographic distribution of falls, impact craters and fireballs. However, the fact that recovery of , fireball observations and discovery of craters are mostly restricted to continental areas, their conclusions are restricted and possibly biased. Space- based observations have contributed recently to improve Fig. 2. Generation of initial conditions over the surface of this situation, but they are also limited by the size and time of impacts. the Earth using the Poisson disk distribution widely applied in ray casting [4].

Challenges and prospects

Our technique is intrinsically inexpensive in terms of computing resources. Still the size of the initial configuration space is huge. In order to tackle this problem, we are developing innovative tools, including scavenging grids of mobile devices. The same technique can be applied to study the distribution of impact in other bodies of the solar system, e.g. the Moon. We are also

attempting to apply the technique to asses the probability Fig 1. The distribution of already known NEOs in the of capture of TCO for future manned and unmanned configuration space. missions. The aim of this work is to asses the problem of estimating in an efficient way the geographical distribution of the References probability of meteoroid impact and/or capture at a given [1] Granvik, M. et al. (2012). The population of natural time. Our technique could be used to study the distribution Earth satellites. Icarus, 218. of impacts of objects of any size, including the largest [2] Appel, A. (1968). Some techniques for shading ones where few data points are available and the smallest machine renderings of solids. AFIPS. [3] Dunbar, D. & Humphreys, G. (2006). A spatial data ones which are mostly unobservable. structure for fast poisson-disk sample generation. ACM Trans. Graph., 25(3). The Age and Probable Parent of the Southern Delta Aquariid Meteor Shower

A. Abedin (1), P. Wiegert (1), P. Brown (1) (1) The University of Western Ontario, London, ON, Canada, N6A 3K7, ([email protected]))

Introduction simulations, in order to investigate the most likely age and parent of the SDAs, by direct comparison of the results of our model to the observed characteristics The Souther Delta Aquariids (SDAs), despite being of the shower. Our observational data consists of ∼ a minor annual shower, it stands out well against the 1400 TV SDAs observed by the Cameras for Allsky sporadic meteor background, and can be detected Meteor Surveillance (CAMS) [8], visual observation from late July to mid-August. The shower has been by the International Meteor Organization (IMO), and well detected by by photographic [1], visual and radar extensive detections by the Canadian Meteor Orbit meteor surveys [2] and is among the dominant shower Radar (CMOR). In our simulations, we considered in the southern hemisphere. The SDAs presently two potential parents of the stream, namely comet ◦ have a mean radiant position (λ − λ⊙) ≈ 210 and 96P/Machholz, and the most notable member of the ◦ β ≈ −8 , given in a sun-centered reference frame, Marsden group of sunskirting comets - comet P/1999 and mean geocentric speed of Vg ∼ 40.3 km/s, with J6 [6]. the activity profile showing a positive (late) skew. We will be discus our preliminary results of these The stream has been associated with comet simulations with an emphasis on the most probable 96P/Machholz e.g., [3], [4] and more recently parent and age of the SDA meteoroid stream. with Marsden group of sunskirting comets e.g., [5], [6]. Moreover, some authors suggested that comet 96P/Machholz and Marsden group of comets, along References with the Kracht group and several other small bodies [1] Wright, F. W., Jacchia, L. G., and Whipple, F. L., and meteor showers share the same origin, perhaps Astronomical Journal, Vol. 62, p. 225, 1957. from a past breakup of a single first progenitor, [2] McKinley, D. W. R., Astrophysical Journal, vol. forming a large complex of interplanetary small 119, p.519, 1954. bodies e.g., [6], [7]. Furthermore, the differential [3] Babadzhanov, P., B., Obrubov, Y., V., Asteroids, perturbations by Jupiter has accelerated the evolution Comets, Meteors 1991, pp. 27-32, 1992. of different members of the complex, placing them [4] Jenniskens, P., Meteor Showers and their Par- presently in a different evolutionary stage of their ent Comets,pp. . ISBN 0521853494. Cambridge, secular Kozai cycle [4]. UK: Cambridge University Press, 2006. However, there has not been any detailed study, [5] Ohtsuka, K., Nakano, S., Yoshikawa, M., PASJ, dedicated to address the observed characteristics of Vol.55, pp. 321-324, 2003. the shower or its origin. Past child-parent associations [6] Sekanina, Z., Chodas, P.,The Astrophysical Jour- of the SDAs and a potential parent, are derived mostly nal Supplement Series, Volume 161, Issue 2, pp. from similarity of their mean orbital elements and 551-586., 2005. evolution of the latter, without an attempt to match [7] Neslusan, L., Hajduková, M.,Jakubík, M., As- and explain the observed characteristics of the shower tronomy & Astrophysics, Volume 560, id.A47, such as, radiant location and drift, activity profile, 10 pp., 2013. distribution of the orbital elements as a function of [8] Jenniskens P., et al.,Icarus, In Press, 2015 the solar longitude etc. With this study we aim to fill this gap, as well as to obtain an overall picture as to the origin and evolution of the meteoroid complex of comet 96P/Machholz. For this purpose, we performed detailed numerical The mass index and total mass of the Geminid meteoroid stream as found with radar, optical, and lunar impact data

R. Blaauw (1) (1) All Points Logistics/Jacobs ESSSA/NASA Meteoroid Environments Office, Marshall Space Flight Center, Huntsville, AL,35812

The Geminid meteor shower was observed in 2015 using the Western Meteor Physics Group’s Canadian Meteor Orbit Radar (CMOR), Marshall Space Flight Center’s (MSFC) eight wide-field optical cameras, and MSFC’s lunar impact monitoring. These observations allowed Geminid fluxes to be calculated in three unique mass-ranges, from 1.8e-4 grams to 30 grams. From these fluxes, a mass index of 1.68 +/- 0.04 is found, which is in excellent agreement with past Geminid mass indices such as 1.69 found by Blaauw et al [1] using only radar data and 1.7 found by Arlt & Rendtel [2] using visual data. This mass index, however, is found over five orders of magnitude of mass, which allows a higher level of confidence that this mass index holds over a large portion of the stream. Mass indices are an important quantity to be accurately measured for a shower, indicating the distribution of mass in a well-studied stream in which we know the parent body (3200 Phaethon), improving forecasts of the shower activity, and allow fluxes to be scaled to high and low masses. The quantities derived here, along with a profile of the Geminid meteor shower activity in 2015 from CMOR, permit the total Geminid mass the Earth encountered in 2015 to be found, along with a minimum total mass of the Geminid meteoroid stream. Attempts have been made in the past to measure the mass of meteoroid streams using ZHR profiles, but here this new and improved treatment uses empirically derived fluxes and measured mass indices for the 2015 encounter with the meteoroid stream. This is to be compared with other meteoroid stream mass estimates including that of the , caused by comet Swift Tuttle.

References [1] Blaauw, R., Campbell-Brown, M., Weryk, R., Monthly Notices of the Royal Astronomical Society, Vol 414 (4), pp 3322-3329. 2011 [2] Arlt, R., and Rendtel, J., Monthly Notices of the Royal Astronomical Society, Vol 367 (4), pp 1721-1726. 2006.

Meteor showers as a means of recovering the past orbital history of comets The case of comet C/1917 F1 (Mellish)

L. Neslusan (1), J. Vaubaillon (2), M. Hajdukova (1) (1) Astronomical Institute of the Slovak Academy of Sciences (2) IMCCE Paris, France; ([email protected])

Introduction We tried to find the appropriate modification of the orbit in the time when the meteoroids of its stream were re- When a swarm of particles is released from the surface of leased. We created 24 cloned orbits and repeatedly mod- a parent body, they start orbiting the Sun along very simi- eled the theoretical streams, assuming various strength of lar orbits to that of the parent comet. Sometimes, the per- P-R drag. We found a cloned orbit which resulted in a turbations of big planets can change the orbits of a part of perfect prediction of the properties of the most problemat- a stream so that it can split into two or more filaments [1]. ic filament. Unfortunately, the simultaneous perfect match If more than a single filament passes through the Earth’s of the other three filaments failed [3]. orbit, we observe several meteor showers associated with the same parent body. In the future, a much more robust modeling could possibly reveal a convergence in cloning at a narrow interval of P- Modelling theoretical streams and studying their dynam- R drag strength. If success was achieved, meteor data- ical evolutions for a suitably long period allows all these bases and meteoroid streams modeling could become alterations of the initial orbital corridors to be revealed. tools for tracing the past dynamical history, caused by the The theoretical predictions are evaluated by comparing action of non-gravitational effects, of the parent comet them to the actually observed meteors. Differences be- that associates more than single meteor shower. tween the observed and predicted filaments of the meteor- oid stream represent the possibility of an eventual recov- Acknowledgements ery of the comets’ orbit evolution. J. Vaubaillon is grateful to the CINES staff for the use of Modeling meteoroid streams using the nomi- the occigen machine on which heavy calculations were nal and cloned orbits of comet C/1917 F1 performed. L. Neslusan and M. Hajdukova acknowledge the support from the Project ITMS No. 26220120009, based on the supporting operational Research and devel- We modeled the theoretical stream of C/1917 F1, which opment program financed by the European Regional De- associates at least two, possibly four, meteor showers that were recorded in the meteor databases. The velopment Fund. Their work was also supported by the of the comet is about 145 years, so its stream needed a Slovak Research and Development Agency under contract relatively long time to spread along the whole orbit. No. APVV-0517-12 (M.H.) and by the VEGA - the Slo- Increasing evolutionary time resulted in a significant part vak Grant Agency for Science, grant No. 2/0031/14 of the test particles also moving into other orbital (L.N.). corridors. This proves that meteoroids in various showers that originate in the same parent body can be of different References ages. [1] Vaubaillon J., Lamy P., Jorda L., MNRAS, 370, 1841- 1848, 2006 However, the appropriate meteor showers were not perfectly predicted by assuming the past evolution of the [2] Neslusan, L. & Hajdukova, M., A&A, 566, A33, 2014 nominal osculation orbit of C/1917 F1, as well as of the [3] Neslusan, L., Vaubaillon, J., Hajdukova, M., A&A, stream meteoroids, only because of the gravitational submitted, 2015 perturbations of planets [2]. Neither did the Poynting- [4] Asklof, S., Arkiv for Mat. Astron. och Fys., 23A, No. Robertson (P-R) drag, influencing the dynamical 11, 1932 evolution of the meteoroids, improved the agreement between the theory and observation sufficiently. Taking various strengths of the P-R drag into consideration, we clearly obtained a better match of three of the four showers [3]. However, when considering the nominal orbit of the parent comet, determined by Asklof with a relatively high precision [4], a perfect match in all four filaments was impossible to reach.

In the past, the orbit of a comet could be significantly influenced and, therefore, modified by non-gravitational effects. The currently observed stream could be, and most likely was, formed when the comet moved in a slightly different orbit than it moved at its last return to the perihelion. Use of Various Metrics in Orbital Spaces while Finding a Common Origin of Celestial Bodies

K.V.Kholshevnikov (1), G.I. Kokhirova (2) (1) St.Petersburg State University, St.Petersburg, Russia, (2) Institute of Astrophysics of the Academy of Sciences of the Republic of Tajikistan, Dushanbe, Tajikistan ([email protected])

Finding a common origin of various celestial bodies, and first of all relations between mete- oroid streams, comets, and asteroids (possibly extinct comets) remains one of the important problems of the Solar System astronomy. Different criteria starting with one by Southworth–Hawkins were used for this purpose. Ideally they must represent some kind of metrics in a 5-dimensional space of orbits. Unfortunately they are not ideal. We have examined properties of major- ity of criteria. It turns out that they all represent pseu- dometrics for which the triangle axiom does not fulfill. Besides, they are inapplicable if at least one of orbits is circular. We propose metrics free of all pointed draw- backs. In addition metric properties of three factor- spaces (where orbits are identified irrespective of: val- ues of longitudes of nodes; values of arguments of pericentres; values of both longitudes of nodes and ar- guments of pericentres) are examined. Results are ap- plied to the problem of searching minor bodies of the Solar System having a common origin. Relationship between comet 2P/Encke and several asteroids is es- tablished, and a conclusion was made on a belonging of asteroids to the Taurid asteroid-meteoroid complex. Using all considered criteria and new metrics leads to practically identical results. It is explained by the fact that only close and essentially non-circular orbits are examined. Besides, the measure of orbit triples for which the triangle axiom failed is likely small, though it does not established yet theoretically, as well as em- pirically. Key words: Keplerian orbits, metric spaces, aster- oid, comet On association of comet 96P/Machholz 1 and asteroid 2003EH1

G.I. Kokhirova (1), P.B. Babadzhanov (1), Yu.V. Obrubov (2) (1) Institute of Astrophysics of the Academy of Sciences of the Republic of Tajikistan, Dushanbe, Tajikistan ([email protected]), (2) Moscow State Technical University named after N.E. Bauman, Kaluga branch, Kaluga

The orbital evolutions of comet 96P/Machholz 1 and the near-Earth asteroid 2003EH1 were investi- gated under the perturbing action of major planets for the time interval of 28 thousand years. Several criteria of orbital similarity such as the Southworth and Hawkins criterion DSH [1], the Drummond cri- terion DD [2] and the criterion DN of Jopek et al. [3] were calculated and their variations were followed during this period. It was shown that comet and as- teroid can be fragments of the same larger comet- progenitor of the Quadrantid complex. According all criteria a break-up of the parent comet possibly oc- curred near 9500 years ago. The near-Earth object 2003EH1 is really the dormant fragment of the par- ent comet’s nucleus. A conclusion was made that comet 96P/Machholz 1, near-Earth asteroid (186256) 2003EH1 and Quadrantids meteoroid stream form the complex of related objects.

References [1] Southworth, R.B., Hawkins, G.S., Smith. Con- trib. Astrophys., 7, pp. 261-285, 1963. [2] Drummond, J.D., 45, Icarus, pp. 545-553, 1981. [3] Jopek, T.J., Valsecchi J.B., Froeschle, C., In: As- teroids III, pp. 645-652, 2000. An Orbital Meteoroid Stream Survey using the Southern Argentina Agile MEteor Radar (SAAMER) based on a Wavelet approach

P. Pokorny1, D. Janches2, P. Brown1, J. L. Hormaechea3 (1) Department of Physics and Astronomy, University of Western Ontario, London, Ontario, Canada ([email protected]) (2) Space Weather Lab., Mail Code 674, GSFC/NASA, Greenbelt, MD 20771, United States (3) Estacion Astronomica Rio Grande, Rio Grande, Tierra del Fuego Argentines

Over a million individually measured meteoroid from the IAU catalogue while 34 showers are new orbits were recently collected with the Southern Ar- and not listed in the catalogue (radiant locations of gentina Agile MEteor Radar (SAAMER) over a pe- newly discovered showers are shown in Figure 1). Our riod of 4 years. We apply a 3D wavelet transform to searching methodology, combined with our large data these data to search for meteor showers in the South- sample, provides unprecedented accuracy in measur- ern Hemisphere. Producing a composite year from all ing meteor shower activity and description of shower 4 years of data enables us to obtain an undisturbed year characteristics in the southern hemisphere. Using long meteor activity with more than one thousand me- a simple modelling and clustering method, we also teors per . Our automated meteor shower search propose potential parent bodies for newly discovered methodology identified 60 showers. 26 of these show- showers. ers were associated with previously recorded showers

Figure 1: The radiant locations for all newly discovered showers in sun-centered coordinates color coded with their geocentric velocity vg (colored circles) where their IAU shower codes are located next to their radiant locations. The Sun is at the origin (0◦, 0◦); the center of the plot (270◦, 0◦) is the apex of the Earth’s motion. Could the Geminid meteoroid stream be the result of long-term thermal fracture?

G.O. Ryabova Tomsk State University, Russian Federation ([email protected])

The previous models by Ryabova have shown that the maximum in the numerical model still was shifted about Geminid meteoroid stream has cometary origin, so aster- one day relatively the observed one. oid (3200) Phaethon (the Geminid’s parent body) is However, careful comparison the model activity profile probably a dead comet. Recently (in 2009 and 2012) some with observations has shown that the Geminids have week activity was observed, but it was not the cometary rather narrow core, which is comparable with the model activity. Recurrent brightening of Phaethon in perihelion one, and very extended low-level activity. This ‘tail’ is could be the result of thermal fracture and decomposition. practically absent in the model. As it was mentioned In this study we model the long-term dust release from above, the results of the Geminid modelling lead us to Phaethon based on this mechanism. cometary origin of the stream. Moreover, they suggest that the dust release has happened during very short time — (3200) Phaethon activity from one half and up to several orbital revolutions. During this catastrophic release of volatiles the cometary orbit The Geminid’s parent body asteroid (3200) Phaethon was could be drastically transformed. Another possibility is discovered in 1983. Since then no activity was observed that the core of the stream was generated by this catastro- until 2009 [1] and 2012 [2]. In both years the scenario was phic dust release, and the wide low-level ‘tail’ by long- identical: about 0.5 days after perihelion passage Phaethon term recurrent perihelion activity. brightened very fast by 1 mag, and the brightness returned to its normal level within 2 days. A hypothesis explaining Long-term thermal fracture modelling this scenario (i.e. why 0.5 days after perihelion, and why only 2 days) was proposed in [3]: the combination of The method of modelling was described in details in [4]. extremely high obliquity (~88°) of the Phaethon pole and The main idea is simple: to simulate particles ejection very small perihelion distance (0.14 au) with ‘thermal’ speed (~100 m s−1) in perihelion every several revolutions and follow their evolution till the pre- Jewitt & Li [1] have analyzed four possible reasons for the sent time. We used Halphen-Goryachev method to calcu- brightening, and considered that the most plausible is the late the particles’ orbital evolution. dust production by thermal fracture and decomposition. They estimated the ejected mass and found that the stream We found that it is not probable that the Geminid meteor- could be produced by this periodical replenishment during oid stream (or its low-active wide tail) was generated by several thousand years. long-time thermal fracture.

Geminid meteoroid stream modelling References

Some time ago the work on the qualitative model of the [1] Jewitt, D. and Li, J., ApJ, 140, 1519–1527, 2010. Geminid meteoroid stream was completed [4, 5]. The [2] Li, J. and Jewitt, D., ApJ, 154, Id. 154 (9 pp), 2013. main discovery was that the stream has two layers, and the [3] Galushina, T.Yu et al. P&SS, 118, 296–301, 2015. peculiar bimodal shape of the observed activity profile [4] Ryabova, G.O., MNRAS, 375, 1171–1180, 2007. conforms to cometary scenario of the stream origin. To [5] Ryabova, G.O., EM&P, 102, 95–102, 2008. calculate orbital evolution of meteoroids the method of [6] Ryabova, G.O., MNRAS, 456, 78–84, 2016. nested polynomials was used, which is about 106 times [7] Ryabova, G.O., Sol. Syst. Res., 33, 224–238, 1999. faster than numerical integration, so it was possible to use statistically-rich models in 10 millions of meteoroid or- bits. However the use of approximations has some shortcom- ings [1]. In the result, the model stream turned out to be shifted in space and more compact relatively the real stream. The next step was the quantitative model. Nu- merical integration is expensive: to calculate a frugal model in 30 000 of particles a usual desktop computer has to make calculations about one month; therefore, it is reasonable to begin with a preliminary model [6]. This numerical model did not improve the situation. The model stream width increased insignificantly, so gravitational perturbations and encounters with the planets are not re- sponsible for the mentioned discrepancy. The shower Detection of meteor shower in 2014

M. Sato (1) , J. Watanabe (2), C. Tsuchiya (2), A. V. Moorhead (3), D. E. Moser (4), P. G. Brown (5), W. J. Cooke (3) (1) Kawasaki Municipal Science Museum ([email protected]), (2) National Astronomical Observatory of Japan, (3) NASA Meteoroid Environment Office, Marshall Space Flight Center, Huntsville, Alabama 35812 , (4) Jacobs, ESSSA Group, Marshall Space Flight Center, Huntsville, Alabama 35812 ,(5) Department of Physics and Astronomy, The University of Western Ontario, London N6A3K7, Canada

Introduction Roque de los Muchachos (ORM) of Instituto de Phoenicids is one of the established meteor shower of Astrofísica de Canarias (IAC) in La Palma at Canary IAU, the number is #254. A strong outburst of the Islands in Spain. However, unfortunately, we could not Phoenicids was recorded in 1956. Its hourly rate of the carry out effective observations except naked-eye maximum peak leached to 300 [1]. No other strong observation at around the peak time mainly due to bad outburst has been reported so far. rainy weather. On the other hand, 5 meteors of Phoenicids The parent body was thought to be 289P/1819 W1 were observed by All Sky Fireball Network of NASA and (Blanpain) which have been lost until 2003. However, a SOMN (Southern Ontario Meteor Network) and their newly discovered asteroid, 2003 WY25, was identified to orbit of meteors was obtained. Moreover, we found 14 be a candidate parent comet 289P/1819 W1 (Blanpain) [2]. candidates of the Phoenicids among the CMOR data. We reported that the strong Phoenicids display in 1956 was caused by a bundle of dust trails formed by dust Results ejected from comet 289P between the 18th and the early While the number of meteors of Phoenicids was not so 19th centuries [3]. Furthermore, we reported the forecast large, unique slow meteors were certainly observed. The of activity of the Phoenicids in 2008, 2014 and 2019 [4]. ZHR of visual observation at the Canary Island was Among them, a situation of the detection of Phoenicids recorded about 30 between 1:00 and 2:00 (UT) on Dec. 2. was best in 2014 because several trails formed in the Although some images of meteors were taken by still early 20th century will approach Earth in 2014. Therefore, cameras, it was difficult to be recognized as Phoenicids we tried to observe Phoenicids in 2014. because of uncertain velocity and larger dispersion of a radiant due to the low velocity. The distribution of the Forecast radiant points from the CMOR, NASA and SOMN was derived as shown in Fig.2. The location of the observed The peak time was expected to be at about 0:00 (UT) on radiant point is consistent with the prediction. December 2 in 2014. The radiant points of predictions are in between Cetus and Sculptor, near by the Deneb Kaitos, where was slightly far from Phoenix (Fig. 1). Because a meteor velocity was very slow, the radiant dispersion is expected to become wider.

Figure 2 The distribution of radiant points

Figure 1 Radiant points of forecast in 2014 References [1] Huruhata, M., & Nakamura, J. 1957, Tokyo Astron. Bull., 2nd Ser., No.99 Observations [2] Foglia, S. et al., B. G. 2005, IAU Circ., 8485 It is thought that the appropriate site for observation is [3] Watanabe, J., Sato, M., & Kasuga, T. 2005, PASJ, 57, around of the Atlantic based on the forecasted peak time. L45 The part of the authors lead by M. Sato and Japanese [4] Sato M., & Watanabe J. 2010, PASJ, 62, No.3, pp.509- members decided to observe at the Observatorio del 513 Precise data on Taurids fireballs obtained by the European Fireball Network during the enhanced Taurid activity in 2015

P. Spurný (1), J. Borovička (1), J. Svoreň (2), H. Mucke (3) (1) Astronomical Institute of the Czech Academy of Sciences, Ondřejov, Czech Republic, (2) Astronomical Institute of the Slovak Academy of Sciences, Tatranská Lomnica, Slovakia, (3) Austrian Astronomical Society, Vienna, Austria. ([email protected])

Introduction tained very complex and precise data on a very high num- ber of Taurid fireballs observable over Central Europe. The Taurid shower belongs to the most active main meteor showers, and has been doing so at least for several Results centuries. It is active over a period of almost three months Since 23 October to 8 December 2015 cameras of the EN (~80° in solar longitude), with a peak in the first week on in the Czech Republic, Slovakia and Austria recorded November. Such long activity means that it is so dispersed more than 150 fireballs which belonged to the Taurid that different parts have been called by different names complex (one example is on Fig 1). It is about 10 times (i.e. Piscids, , Taurids or χ-) and over all higher number of Taurids than we usually record in this this activity, the stream has northern and southern period. All of these Taurid fireballs are recorded at least branches [1]. Therefore structure of this stream is very from two stations so all parameters concerning their complicated and therefore it is better to speak about the atmospheric trajectories and heliocentric orbits could be Taurid complex. The shower is known for its spectacular determined. Quality of results is naturally affected by several factors (distance from the cameras, brightness and fireballs, which means that it is quite a rich also for larger length of each fireball, weather conditions) and thus meteoroids. Exceptionally, Taurid shower has also differs from case to case, but at least 100 Taurids are occasional outbursts [2]. Here we report instrumental determined with very high accuracy and reliability. Most observations of the significant enhancement of the activity of them have also very good dynamics and photometry of Taurid fireballs which was recorded by the European including precise and detailed light curves. These cases fireball network (EN) mainly during the first two weeks of are very suitable for detailed orbital and physical studies November 2015. of the material belonging to the Taurid complex, in particular concerning the large and very large meteoroids. Instruments and data acquisition Our dataset contains meteoroids from several grams to several kilograms with one extreme of almost 2 tons, Successful instrumental recording of this extraordinary which produced a superbolide of –19 ! activity is another tangible result of the systematic opera- One almost Earth grazing Taurid with duration of about 10 tion and modernization of the mainly Czech part of the seconds was also recorded. These results will be summarized in the talk. EN. This network has been modernized several times [3], but the last significant improvement, which was crucial for the presented results, has been realized during the last three years when a high-resolution digital autonomous fireball observatory (DAFO) was developed and gradually installed alongside the older "analog" (using photographic films) autonomous all-sky system (AFO) on all 13 Czech stations and on one station in Slovakia and Austria. Apart from the imaging system, both camera types are equipped with rapid photometers (5000 samples per second) and mechanical (AFO) or electronic (DAFO) shutters with 15, respectively 16 interruptions per second. The sensitivity limit is -4 mag for AFO (about 3 mag lower during a full Moon) and -2 mag for DAFO (with almost no dependence on the ). Fireball observations made with this new digital autonomous system contain more information especially in the beginning and terminal parts of the lumi- Fig 1 Southern Taurid fireball of -14 mag recorded by the DAFO at the Czech station Kocelovice on 25 October 2015. nous trajectory. They are also significantly more efficient, and, when combined with improved analysis techniques, they are more precise than results from any previous sys- References tem. One of its important advantages is the ability to take usable photographic records also during periods when it is [1] Jenniskens, P. Meteor showers and their parent comets. not completely dark (twilight periods) and not completely Cambrige Univ. Press, 790pp, 2006 clear. Thanks to this new observing system and also by [2] Spurný, P. ACM conference 1996, Versailles, poster the fact that weather conditions were surprisingly good in presentation, 1996 Central Europe in the beginning of November, we ob- [3] Spurný P. et al., in Proc. IAU Symp.236,121-130, 2006 Enhanced Activity of the 2015 Taurids

P. Żołądek (1),M. Wiśniewski (1,2), A. Olech (1,3), R. Rudawska(7), Z. Tyminski (1,4), M. Bęben (1), T. Krzyżanowski (1), M. Maciejewski (1), K. Fietkiewicz (1), M. Gozdalski (1), M. P. Gawroński (1,5), T. Suchodolski (1,6), M. Myszkiewicz (1), M. Stolarz(1), K. Polakowski (1), W. Węgrzyk (1) ([email protected])

(1) Polish Fireball Network, Comets and Meteors Workshop, ul. Bartycka 18, 00-716 Warsaw, Poland , (2) Central Office of Measures, ul. Elektoralna 2, 00-139 Warsaw, Poland , (3) Nicolaus Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warsaw, Poland, (4) National Centre of Nuclear Research RC POLATOM, Sołtana 7, Otwock- Świerk, Poland, (5) Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziądzka 5, 87-100 Toruń, Poland, (6) Space Research Centre, Polish Academy of Sciences, ul. Bartycka 18A, 00-716 Warszawa, Poland, (7) ESA European Space Research and Technology Centre, Noordwijk

Introduction

On the night of 31.10.2015 enhanced activity of the Southern Taurids has been observed. During evening hours dozens of bright Taurids has been observed by Polish Fireball Network cameras, 19 STA orbits has been determined, vast majority between 19:00 and 21:00UT. Two extremely bright fireballs has been observed. The first, -16 magnitude Southern Taurid has been recorded over north-western Poland at 18:05UT. The second fire- ball passed through the sky at 23:13UT and reached -14 magnitude. Trajectories and orbital elements of both fire- balls has been calculated. Comparison of the orbital ele- ments with available NEO databases with usage of Drummond criterion revealed close similarity to the 2005UR and 2005TF50 asteroids. Both asteroids and both fireballs are close to the 7:2 resonance with Jupiter which is consistent with earlier models (Asher, 1991). The latest comparisons with the most actual NEODYS database revealed another one asteroid - 2015TX24 which has almost identical orbit with the second observed fireball

(D' = 0.0056). 2015TX24 approached the Earth on 29.10.2015, just two days before the maximum. This as- teroid can be treated as the one of the largest members of the 7:2 resonance fireball stream. Such large potential meteoroids can be directly detected by present day NEO surveys.

References

[1] Asher, D.J., 1991, The Taurid meteoroid complex, PhD thesis, New College, Oxford Artificial Meteor and Chelyabinsk Ablation Test using Arc-heated Wind Tunnel

S. Abe, K. Araki, T. Iwasaki, K. Toen (1), H. Sahara (2), T. Watanabe (3), L. Okajima (4) (1) Nihon University, Department of Aerospace Engineering ([email protected]), (2) Tokyo Metropolitan University, Department of Aerospace Engineering, (3) Teikyo University, Department of Aerospace Engineering, (4) ALE CO., LTD. metallic materials with controlling internal porosity. Real Introduction meteorites such as Chelyabinsk (LL5) and Jbilet Winselwan (CM2) were also used for ablation test. Table From a scientific point of view, the attempt to understand 1 summarizes the test samples shown in this paper. Table 1 Test pieces for meteor ablation test. the nature of meteors is of importance because the atmospheric composition, the presence of water and the Composition Mixing ratio Porosity [%] life on Earth are affected or originated by space material FeO – 20.0 – 31.5 even today. However for natural meteors, the mass, composition and the density of the meteoroids are all Fe, SiC 1:1 23.9 – 37.3 unknown. Since the meteor is unexpected transient Fe, Mg 1:1 34.5 phenomenon on the sky it is rather difficult to determine these physical parameters with high precision. Since 1963 (Mg,Fe)2SiO4 Olivine 13.7 – 24.2 the NASA Langley Research Center and the Smithonian Fe, Mg, Al, C 1:1:1:1, 9:9:1:1 17.7 – 44.4 Astrophysical Observatory conducted a series of sounding Chelyabinsk LL5 ~6 rocket flights to simulate natural meteor conditions [1]. There still exists a controversy about luminosity Jbilet Winselwan CM2 ~23 coefficient that is important parameter to estimate the Shapes; cylinder & bullet types. Size; Φ10 meteor brightness. In recent years observations of re-entry capsules from the interplanetary space were performed by using comet sample return and Hayabusa asteroid sample return capsules [2,3,4]. Several unknown emission lines were identified by the re-entry of Hayabusa spacecraft [4]. We scheduled to launch a small commercial satellite by which artificial meteoroids are ejected and are de-orbited to enter the atmosphere [5]. Thus laboratory experiment is important for testing materials to make bright artificial meteors, which takes a new step toward understanding the meteor ablation.

Fig 2 UV-VIS spectra of meteor ablation plasma. Chelyabinsk, Jbilet Winselwan and Olivine artificial meteors are compared.

References Fig 1 Meteor ablation by arc-heated wind tunnel. [1] Ayers, W. G., McCrosky, R. E., and Shao, C.-Y., 2 Meteorites (left) and 3 artificial meteor samples (right). Photographic Observations of 10 Artificial Meteors, SAO Method Special Report No. 317, 1970. [2] Jenniskens, P., Observations of the Stardust Sample In order to observe details of a meteor ablation process Return Capsule Entry with a Slitless Echelle Spectrograph, such as temperature, emitting composition ratio, J. of Spacecraft Rockets, Vol. 47, No. 5, pp 718-735, 2010. fragmentation phenomenon and their time variations, the [3] Borovička, J., Abe, S., Shrbený, L., Spurný, P., Bland, artificial meteor ablation experiment was carried out using P. A., Photographic and Radiometric Observations of the the arc-heated wind tunnel operated by JAXA/ISAS HAYABUSA Re-Entry, Public. Astron. Soc. Japan, Vol. (Japan Aerospace eXploration Agency / the Institute of 63, No. 5, pp 1003-1009, 2011. Space and Astronautical Science). An arc-heated wind [4] Abe, S., Fujita, K., Kakinami, Y., Iiyama, O., tunnel is widely used for ground-based experiments to Kurosaki, H., Shoemaker, M. A., Shiba, Y., Ueda, M., simulate environments of the planetary Suzuki, M., Near-Ultraviolet and Visible Spectroscopy of under hypersonic and high-temperature conditions. To HAYABUSA Spacecraft Re-Entry, Public. Astron. Soc. simulate hypersonic entry velocity over 12 km/s, high- Japan, Vol. 63, No. 5, pp 1011-1021, 2011. 2 heating rate, ~30 MW/m , and high-enthalpy conditions, [5] Watanabe, M., Sahara, H., Abe, S., Watanabe, T., ~10,000 K arc-heated air-flow at velocity ~6 km/s Nojiri, Y., Okajima L., Development of artificial meteor (0.6MPa), were achieved. For this laboratory experiment, for observation of upper atmosphere, Acta Astronautica, we developed artificial meteor samples composed of Vol. 121, pp 172-178, 2016. Photometric Stellar Catalogue for TV meteor Astronomy V.A.Leonov and A.V.Bagrov Institute of Astronomy of Russian Academy of Science

Ordinary meteor observations to provide maximal limiting magnitude for meteors use whole spectral band of visible light. As well-known photometric catalogues were adjusted to astrophysical purposes and present stars’ brightness in middle-band or narrow-band photometrical systems, they cannot be directly used for meteor observations processing. We present a special photometric catalogue of 93 stars that contains extra-atmospheric light flux from the stars directly in energy units just in the spectral band where WATEC LCL 902 is sensitive. All data were calculated as integral from multiplication of the spectral sensitivity of the ICX429ALL sensor and energy distribution in each star emission for 25-angstrem wavelength bands. Presented Photometric Catalogue covers northern hemisphere stars with brightness above mv = 4,0m. As meteors are shining at the very upper atmosphere, their optical observations are done through the same atmosphere as referred stars, so all calculated meteor luminance’s will be obtained directly in extra-atmospheric energy units. The Catalogue is planned to be available for all meteor observers.

Страница A Spectral Analysis of Ablating Meteors

Kevin Bloxam, M. D. Campbell-Brown University of Western Ontario, London ON Canada ([email protected])

When meteoroids collide with the line strength as functions of meteoroid atmosphere, they produce streaks of light, speed, size and origin. The results will place the result of excited and ionized atoms from additional constraints on meteoroid composition for ablation modelling, and both the meteoroid – specifically metals - inform studies of luminous efficiency, which and the atmosphere. Four of the main depends strongly on the bright lines present elements accessible through spectral in meteor spectra. Figure 1 shows an observations of faint meteors are iron, example of a complete set of light curves sodium, magnesium, and calcium at the produced from an event captured on respective wavelengths of 394, 436, 520, September 13, 2015 from the CAMO and 589 nm. Though these elements tracking system and the Fe, Na, and Mg cameras. normally do not represent the main constituents of the meteor, they are important tracers for different minerals that may be present. Borovicka (2007) used the ratio of the brightness of the iron, magnesium and sodium lines to categorise meteors of different origins. The Canadian Automated Meteor Observatory (CAMO) observes meteors from two stations in white light, using image intensified video, allowing their light curves, Figure 1: Comparison of the white light, Mg, Na, and Fe light curves captured from an event on Sept. 13, 2015. The trajectories, and orbits to be calculated. three filtered light curves have been scaled to the white From September to December 2015, four light curve observed by the CAMO tracking system. additional intensified cameras were added to the system, each equipped with a notch References filter, and set up to observe approximately the same volume of sky as the CAMO Borovicka, J. (2007). Properties of meteoroids tracking system, so that meteors are fully from different classes of parent bodies. characterized in white light as well as the Proceedings of IAU Symposium 236, 2, 107— most important meteor spectral lines. 120.

This unique dataset will be used to investigate differential ablation and spectral

Modelling non-fragmenting meteoroids

M. Campbell-Brown The University of Western Ontario, London ON Canada ([email protected])

Meteoroid ablation models are used to gain insight into the composition and fragmentation behaviour of meteoroids. In particular, the equations of meteor ab- lation are used to match measured meteor light curves and deceleration, with the fragmentation and thermal and physical properties of the meteoroid being ad- justed to produce the best match.

The Canadian Automated Meteor Observatory (CAMO) tracking system is capable of imaging faint meteors with a resolution on the scale of meters, re- vealing details of the meteoroids’ fragmentation. At- tempts to match thermal disruption and thermal ero- sion models of meteor ablation to CAMO meteors re- vealed that the models greatly overpredict the amount Figure 1: High-resolution image of a non-fragmenting of wake seen in the high-resolution system [1]. This meteor observed with the Canadian Automated Meteor indicates that the models rely too much on fragmenta- Observatory. tion to match light curves. References Non-fragmenting meteors produce a characteristic, late-peaked light curve in standard ablation models, [1] Campbell-Brown, M. D., Borovicka,ˇ J., Brown, while meteors showing little or no fragmentation on P. G., Stokan, E. (2013) High-resolution mod- the CAMO tracking system have light curves which elling of meteoroid ablation. Astronomy & As- are symmetric overall [2]. Symmetric light curves, trophysics, 557, 41-54. then, cannot be taken as evidence of fragmentation for meteoroids in this size range. [2] Subasinghe, D., Campbell-Brown, M. D., Stokan, E., (2016). Physical characteristics of faint meteors by light curve and high-resolution A single body model which includes chemical inho- observations, and the implications for parent mogeneities and which allows the shape and/or poros- bodies. Monthly Notices of the Royal Astronom- ity of the meteoroid to change with time has been ical Society, 457, 1289-1298. developed to produce non-classical light curves with non-fragmenting meteoroids. The model allows the physical and thermal properties of each of the com- ponent minerals to be specified, including the density, boiling point, specific heat, heat of ablation and lu- minous efficiency. It takes into account the changing porosity when more volatile materials ablate early in the trajectory, and allows the shape of the meteoroid to change with time. The model will be used to inves- tigate the range of light curves which can be produced with non-homogenous, non-fragmenting meteoroids. Detailed modeling of meteor entry at low altitudes

B. Dias, A. Turchi, J.B. Scoggins, T. Magin von Karman Institute for Fluid Dynamics (VKI), Brussels, Belgium ([email protected])

Introduction state-of-the-art models included in the Mutation++ li- brary, developed at VKI [3]. A radiation solver is During the atmospheric entry of meteoroids, ablation also included, using a Hibrid statistical narrow band products interact with the ionized gas surrounding the (HSNB) method showing an accurate description of meteoroids and are driven to the wake, giving a sig- the radiative flux with low CPU cost for coupling with nature that can be detected by radars. Recent efforts CFD tools [4]. have been made by the Belgian Institute for Space The flow governing equations are solved through Aeronomy to estimate the velocity and trajectory of a 1D Stagnation-line CFD solver coupled with the meteors, by means of an innovative technique based Mutation++ library where the gas-surface interaction on radio waves. The Belgian Radio Meteor Stations boundary condition is implemented. (BRAMS) [1] experiment consists of a series of re- The melting of the material will be modeled by solv- ceivers spread all over Belgium to study the meteor ing Stefan problem through a coupling of a 1D mate- atmospheric entry to collect and standardize meteor rial code with a flow solver. By this means it will be observation data. The estimation of meteoroid mass possible to track the fusion interface and to estimate flux is particularly difficult to quantify from radar ob- the amount of mass that is removed by mechanical ero- servations alone, and it is necessary to augment obser- sion. vation data with numerical modeling to have a reason- In the final manuscript we will analyze the the ab- able estimate of the flux of meteoroid material to the lation of meteors at altitudes at lower than 70 km with atmosphere. In this project we propose to study the low entry velocities. Stagnation-line simulations for meteor ablation with a numerical approach similar to meteors of different sizes will be performed account- those used in the aerospace community to model the ing for the physical phenomena described above. gas-surface interaction over thermal protection system materials [2]. References [1] Belgian Institute for Space Aeronomy, BRAMS Methodology (Belgian RAdio Meteor Stations), http:// brams.aeronomie.be/pages/home. We apply a strategy based on an aerospace- [2] Milos, F. and Rasky, D.J., Journal of Thermo- engineering-derived approach (i.e., steady-state CFD physics and Heat Transfer, Vol. 8, pp. 24-34, with surface ablation model). A boundary condition to 1994. describe the interaction between the atmosphere and [3] Scoggins, J.B. and Magin,T., Development of objects with a complex elemental composition is de- Mutation++: MUlticomponent Thermodynamics veloped. This interaction is modeled by solving an And Transport properties for IONized gases li- open-system multi-phase chemical equilibrium prob- brary in C++, 16–20 June 2014, Atlanta, USA, lem (i.e., gas-solid) by means of a solver able to han- 2014. dle materials composed by multiple compounds. The [4] Soucasse, L., Scoggins, J.B., Riviere, P., Magin, boundary conditions consist in solving a surface mass T.E. and Soufiani, A., Flow-radiation coupling balance and a surface energy balance enabling the so- for atmospheric entries using a Hybrid Statisti- lution of the surface temperature and the amount of cal Narrow Band model, Journal of Quantitative mass ablated. Spectroscopy and Radiative Transfer (in press) The closure of the Navier-Stokes equations is done by computing the thermodynamic and transport prop- erties of the flow field. This is achieved by detailed The CAMSS Meteoroid Elemental Abundance Applications and Modeling Results

P. Gural (1), P. Jenniskens (2), M. Hannan (2) (1) Gural Software Development, Sterling, Virginia USA, (2) SETI Institute, Mountain View, California USA

Introduction calibration, spectral modeling formulations for neutrals and ions from both warm and hot components, and a GUI The Cameras for All-sky Meteor Surveillance for element selection and model fit tuning. Spectroscopy (CAMSS) project [1] has been operationally collecting data since April 2013. Over 1000 spectra have Figure 1 shows the user interface of the spectral been identified and archived for elemental abundance coincidence tool. Included in the tool are tunable estimation. Along with those meteor spectra are the parameters such as the user’s choice of element associated Solar System orbits derived from each of the contributors to the measured spectrum, the PSF emission CAMS coincident meteor trajectories, enabling an line width, warm and hot plasma temperatures, air-mass assignment of meteoroid composition to a parent body. adjustment to the extinction, the grating orientation The analysis work flow has been streamlined into several relative to the sensor and its effective dispersion, warm to user interactive (UI) applications. The analysis team feels hot plasma volume ratio, and the column densities per that the step-by-step procedures have reached full maturity element. Many of the spectral modeling formulations are and now analysis of all the spectra is underway. First based on [3-4]. results will be presented. Planned Activity and Goal Methodology The three core applications for responsivity, extinction, The CAMSS system employs sixteen objective-grating and abundance estimation have been implemented and low-light video cameras that operate every clear night tested. The discussion will walk through the various from Sunnyvale, California. The sensor design, hardware modeling choices, algorithmic processing steps and configuration, video capture, automated spectrum preliminary analysis results of the current applications. detection, and data storage have been previously outlined [1]. The more recent focus has been on the calibration, The goal for processing the large archive of spectra is that extraction, and analysis tools with the automation/UI it will provide a year-round survey of the main elemental trade-offs necessary for analyzing a large quantity of high compositions (Mg, Fe, Na) of meteoroids from a diverse dispersion spectra in a consistent and efficient manner. array of comets and asteroids that pass close to Earth. Several GUI based analysis tools were created that include a sensor responsivity application, a bright star spectral References catalog, atmospheric extinction modeling, spatial- [1] Jenniskens P., Gural P., Berdeu A., Meteoroids 2013 temporal coincidence between CAMS and CAMSS tracks, Proceedings, 117-124, 2014. astrometric mapping from trajectory to wavelength, a full [2] Jones W., MNRAS 288, 995-1003, 1997. set of elemental emission line metadata, both warm and hot plasma modeling, an algorithm for electron number [3] Borovicka J., A&A 279, 627-645, 1993. density estimation [2], measurement extraction and [4] Jenniskens P., Adv. Space Res. 39, 491-512, 2007

Fig. 1 Screen shot of the coincidence and elemental abundance estimation application SP_Coincidence. Optical Flash Expansion Geometry in Hypervelocity Impact Events

Y. M. Hew, S. Close, I. Linscott Dept. of Aeronautics and Astronautics Engineering, Stanford University, USA ([email protected])

Abstract

Space environment conditions such as background plasma and presence of neutral species from space weather events can setup spacecraft conditions which can amplify the threat from hypervelocity impacts. Hypervelocity impactors, Meteoroids and orbital debris, travel between 7 to 72 km/s in the solar system. When they impact onto the spacecraft, their high kinetic energy will be converted into energy of ionization and vaporization within a very brief timescale, and result in a small and dense expanding plasma with a very strong optical flash. The radio frequency (RF) emission produced by this plasma can lead to electrical anomalies within the spacecraft and cause catastrophic system failure within the spacecraft. During the impact, a very strong impact flash will be generated. By studying the geometry of the optical flash, we hope to study the impact generated gas cloud/ plasma properties, and advance our understanding of the hypervelocity impact events.

The impact flash emitted from a ground-based hypervelocity impact test is long expected by many scientists to contain the characteristics of the impact generated plasma, such as plasma temperature and density. In this paper, we present a study that correlates the impact flash expansion geometry with the external electric field and the impact generated plasma. The time-resolved optical emission is measured by three photomultiplier tubes in both an electrostatic dust accelerator and a light gas gun facility. The impact target is a thin tungsten film, and it will be charged to various potential to simulate the spacecraft charging conditions in orbit. High speed imaging stereo cameras are also used in the light gas gun facility to capture the evolution of the impact flash. The optical emission expansion geometry (the optical cone) is found to be dependent on the external electric field direction around the impact target and the expanding plasma condition. For biased target, the optical expansion cone exhibit a stronger directionality corresponding to the external electric field and shows a narrower optical cone. For grounded target, the optical expansion cone is wider and less dependent of the external electric field direction. Annual occurrence of meteorite-dropping fireballs

N.A. Konovalova (1), T.J. Jopek (2) (1) Institute of Astrophysics of the Academy of Sciences of the Republic of Tajikistan ([email protected]), (2) Institute Astronomical Observatory, Faculty of Physics, A.M. University, Poznan, Poland

December, and 7th January and the minor ones around Introduction 16th April, and 9th February. Histogram of numbers of both meteorites with the known fall dates and of the The event of has brought about meteorite-dropping fireballs is shown in the figure below. change the earlier opinion about limits of the sizes of potentially dangerous asteroidal fragments that crossed the Earth's orbit and irrupted in the Earth's atmosphere making the brightest fireball. The observations of the fireballs by fireball networks allows to get the more precise data on atmospheric trajectories and coordinates of predicted landing place of the meteorite. For the reason to search the periods of fireball activity is built the annual distribution of the numbers of both meteorites with the known fall dates and of the meteorite-dropping fireballs versus the solar longitude. The resulting profile of the annual activity of meteorites and meteorite-dropping fireballs shows several periods of increased activity in the course of the year. Figure. Annual activity profiles of meteorite-dropping sporadic fireballs (top) and meteorites (bottom). Data processing and analysis References The analysis of the atmospheric trajectories of sporadic meteorite-dropping fireballs observed in Tajikistan by [1] Summary catalogue of orbital elements and light instrumental methods [1] in the summer‒autumn periods curves of the meteors photographed in the Institute of of increased fireballs activity has been made. The physical Astrophysics, Tajik Academy of Sciences (Dushanbe). properties of fireballs in terms of different methods Editor P.B. Babadzhanov, (2006), Dushanbe, “Donish”, (beginning velocities and heights, initial mass, dynamic 207 p. pressures at the height of fragmentation or bright flare) [2] Southworth, R.B., Hawkins G.S, Smith. Contrib. were calculated. As a result the structural strength, the Astrophys., Vol.7, pp. 261-285, 1963. bulk density and terminal mass of the studied fireballs that [3] Jopek, T.J., Williams, I.P. Highlights of Astronomy, can survive in the Earth atmosphere and can be meteorites Vol. 16, pp. 143-145, 2015. was determined. From the photographic IAU MDC_2003 meteor database and published sources based on the orbit proximity as determined by Dsh-criterion of Southworth and Hawkins [2] the fireballs that could be the members of group of meteorite-dropping fireballs, was found. Among the near Earth's objects (NEOs) the searching for parent bodies for meteorite-dropping fireballs was made on the base of Dsh- criterion of Southworth and Hawkins. As orbits evolve rapidly in the solar system, just a similarity of orbits at the present time is not sufficient to prove a relationship [3]. The evolution of orbits of these objects in the past on a long interval of time was investigated to show that the evolution is similar.

Conclusions

From statistics of recorded meteorite-dropping fireballs and meteorites we have found four major and two minor increases in fireball activity within a year. The major ones occur around dates 1st August, 24th October, 4th Archive data mining – the

P. Koten (1) (1) Astronomical Institute of ASCR, Ondrejov, Czech Republic ([email protected])

Introduction

For recently introduced automatic video observation system MAIA [1] the data processing pipeline was developed. Now the methods were improved to allow also the processing of the archive analogue data recorded on the video tapes.

Methods

The regular double station observations of the meteor showers are carried out at the Ondrejov observatory since 1997 [2]. From the beginning the analogue video systems were employed. The recorded data were stored in the archive. Now we are using new methods to mine the archive data.

New automatic digital system is currently used for the double station observation. The data recorded during the night are search for the meteors using dedicated software. Then the standard methods for the atmospheric trajectories and the heliocentric orbits are used. Such a processing technique can be used also for the archive data when it is converted into appropriate format.

Lyrid meteor shower

The Lyrid meteor shower was among the showers on the list of interesting events since the beginning of the double station experiment. It resulted in big number of double station meteors recorded in recent years.

Summary

Now we employ new methods to processing this archive data. The methods will be shortly presented as well as the results of the double station observations.

References

[1] Koten, P., Fliegel, K., Páta, P., and Vítek, S., Earth, Moon and Planets, Vol. 108, pp. 69-76, 2011. [2] Koten, P., Borovi čka, J., Spurný, P., Betlem, H., and Evans, S., Astronomy and Astrophysics, Vol. 428, pp. 683- 690, 2004. Emission spectroscopy of poorly-known and recently discovered meteoroid streams: the SMART Project

J.M. Madiedo (1,2) (1) Departamento de Física Atómica, Molecular y Nuclear, Universidad de Sevilla, Spain, (3) Facultad de Ciencias Experimentales, Universidad de Huelva, Spain ([email protected])

and the orbital data of the parent meteoroids were Introduction calculated in the usual way [6]. The association with the above-mentioned showers was performed by employing

the Southworth and Hawkins dissimilarity criterion [7], Emission spectroscopy plays a fundamental role in meteor with DSH<0.15. The analysis of these spectra is providing science, since this provides information about the information about the conditions in the meteor plasma and chemical nature of meteoroids ablating in the atmosphere clues about the chemical composition of the progenitor [1, 2, 3, 4]. For this reason, an array of spectrographs has meteoroids. been deployed at several meteor observing stations operated by the University of Huelva in Spain. The first of these devices, which were based on low-lux CCD video cameras endowed with holographic diffraction gratings, started operation in 2006 at the station in Sevilla and also at the Cerro Negro mobile station [5]. Later on, slow-scan CCD spectrographs were also employed at both locations. Nowadays, these spectral cameras operate in a fully autonomous way at 9 meteor stations in the framework of the SMART project, which is the acronym for Spectroscopy of Meteoroids in the Atmosphere by means of Robotic Technologies. The spectra of meteor events associated to poorly-known and recently discovered meteoroid streams are of special interest, since these can provide new clues to improve our knowledge about these Fig 1. Emission spectrum produced by a λ-Ophiuchid swarms. meteor recorded on 22 June 2014 at 3h19m59s UT.

Instrumentation Conclusions The spectrographs operating in the framework of the SMART Project work in a fully autonomous way thanks The SMART project is providing meteor spectra by means to the MetControl software [6]. Some or these systems are of automated video and slow-scan CCD spectrographs based on low-lux CCD video cameras (models Watec deployed in 9 meteor stations along Spain. The first of 902H and 902H Ultimate). These employ aspherical fast these systems started operation in 2006, and the main lenses (f1.0 to f1.2) covering fixed fields of view ranging effort focuses on the analysis of spectra of meteor events from about 90ºx60º to 8ºx5º. To disperse light emitted by associated with poorly-known and recently discovered bright meteors, a holographic transmission diffraction meteoroid streams. The analysis of these signals will grating is attached to the objective lens. Emission spectra produced by events brighter than mag. -4/-5 can be provide valuable information about the chemical nature of obtained in this way. On the other hand, five slow-scan the parent meteoroids. CCD cameras are also employed as imaging devices. These cover a field of view of ~50ºx50º and are placed on automated alt-az mounts. In this way, they can be pointed References to arbitrary regions of the sky. They can image emission [1] Borovicka, J. (1993) Astron. Astrophys. 279, 627-645. spectra for fireballs brighter than mag. -6/-7. [2] J.M. Trigo-Rodríguez et al. (2003) MAPS 38, 1283- 1294. Emission spectra [3] Trigo-Rodriguez, et al. (2009) MNRAS 392, 367–375. [4] Madiedo, J.M. et al. (2013) MNRAS 433, 571. Over 200 emission spectra of meteor events belonging to [5] Madiedo, J.M. & Trigo-Rodriguez, J. M. (2008) EMP recently discovered or poorly known showers have been 102, 133. recorded in the framework of the SMART Project. As a [6] Madiedo J.M. (2014), Earth, Planets and Space, 66, sample, Figure 1 shows the calibrated signal (integrated 70. along the atmospheric path and corrected for the [7] Southworth R.B., Hawkins G.S. (1963). Smithson instrumental efficiency) obtained for a λ-Ophiuchid meteor. The atmospheric path and radiant of these events Contr. Astrophys., 7, 261. RF Emissions from Meteoroid Hypervelocity Impacts A. Nuttall, A. Goel, M. Hew, P. Tarantino, I. Linscott, S. Close Stanford University

The space environment poses a number of unique hazards to spacecraft, including hypervelocity meteoroid impacts. While impacts from large meteoroids can cause mechanical damage, impacts from dust sized particles can create unwanted, potentially damaging electrical effects. While the high energy mass/velocity meteoroid impact configurations that can be seen in orbit cannot be experimentally recreated on the ground, the lower energy configurations were tested. Ground-based tests were conducted at dust accelerator and light gas gun facilities to investigate into the creation of RF pulses from hypervelocity impact events. Impact cases were run with varying bias voltages on the target to recreate the natural spacecraft charging conditions that can occur in orbit. RF emissions were observed under a number of different test conditions with different potential causes. Low power emissions were observed directly after time of impact at the dust accelerator facilities for negatively biased targets. These low power signals were isolated using novel noise filtering techniques and exhibited highly transient and broad spectrum content. The strength of this emissions correlate with impact plasma production and target bias, suggesting a bulk electron acceleration as the source of the emission. In the presence of a larger plasma plume produced from a light gas gun impact, RF emissions were observed on a grounded target. A pulse was present directly at time of impact, and a series of additional pulses were observed in the following microseconds due to secondary collisions. While the RF signals observed in these ground- based tests are low power, they have the ability to scale by orders of magnitude in high mass/velocity impact events that naturally occur in orbit.

Properties of meteoroids derived using narrow-band synthetic photometry

F. Ocaña (1), J. Zamorano (1), E. Solano (2,3) (1) Departamento de Astrofísica y CC. de la Atmósfera, Universidad Complutense de Madrid, Spain (fog@astrax.fis.ucm.es) (2) Centro de Astrobiología, Departamento de Astrofísica, P.O. Box 78, E-28691 Villanueva de la Cañada, Madrid, Spain (3) Spanish Virtual Observatory

Introduction

The use of photometry in Astrophysics provides infor- mation about the nature and properties of the celestial objects and astronomical phenomena. In the case of line-emission spectra, selected narrow-band filters could gather as much information as low resolution spectroscopy. This work proposes a definition of a set of narrow-band filters [1] and its further use on a fireball spectrum catalogue [2] using synthetic photometry. The system is designed to maximise Figure 2: Fireball spectrum (blue) with photometric the scientific return and try to derive physical and points measured using VO tool (red). It shows how chemical properties of the meteors. We discuss the these points contain much of the information of the results from narrow-band photometry compared to spectrum. theoretical and observational spectroscopic data (e.g., differential ablation for different lines; colour-colour diagrams). References

The filter collection is available at the Filter Pro- [1] Ocaña, F., Zamorano, J., and Gallego, J., Pro- file Service of the Spanish Virtual Observatory ceedings of the International Meteor Conference, (http://svo.cab.inta-csic.es). 15–18 September 2011, Sibiu, Romania, 2011. [2] Vojácek,ˇ V., Borovicka,ˇ J., Koten, P., Spurny,` P., and Štork, R., Astronomy & Astrophysics, Vol. 580, pp. A67, 2015. [3] Abe, S., Yano, H., Ebizuka, N., and Watanabe, J.-I., Earth, Moon, and Planets, Vol. 82, pp. 369– 377, 1998.

Figure 1: Proposed photometric system based on narrow-band filters [1], represented over a sample of firebal spectrum from [3]. Properties of meteoroids observed by the Earth-orbiting Cluster spacecraft

J. Vaverka (1), A. Pellinen-Wannberg (1, 2), J. Kero (2), I. Mann (1,3), C. Norberg (1), M. Hamrin (1), T. Pitkänen (1), A. De Spiegeleer (1) (1) Department of Physics, Umeå University, Umeå, Sweden ([email protected]) (2) Swedish Institute of Space Physics, Kiruna, Sweden, (3) EISCAT Scientific Association, Kiruna, Sweden

Abstract

Most of the Earth-orbiting satellites do not have conventional dust detectors. When a micrometeoroid hits a spacecraft, it induces an expanding plasma cloud, which can be recorded by electric field probes as brief, high amplitude voltage spikes. A systematic search has shown that the Cluster Wide-Band Data (WBD) instrument can monitor hypervelocity impacts. There are though many issues that must be taken into account when analysing the observed events. The Cluster 1 satellite operates since 2009 in a monopole mode after several antenna failures. This benefits meteoroid observations since monopole detectors are much more sensitive to dust impacts than dipole antennas. The automatic gain control applied by the WBD instrument adjusts the dynamic range of the recorded signals. The impact signals can be affected both by saturation or be too weak for analysis depending on which gain level was active on the instrument when they occurred. Even natural waves can confuse the observations. Since Cluster is a magnetospheric mission, the instruments are not recording data throughout the whole orbit. A review will be given showing some events observed with Cluster so far, what properties of the meteoroids can be resolved, what are the benefits and limitations of the method in respect to Cluster and what can be expected to be found in the further dust impact search.

A Reproducible Method for Determination of the Meteoroid Mass Index : Application to CMOR data

P. Pokorny, P. Brown Department of Physics and Astronomy, University of Western Ontario, London, Ontario, Canada ([email protected])

The measurement of the distribution of meteoroid We derive uncertainties in the mass index based on the masses is commonly defined by the differential power posterior samples of Bayesian statistics provided by law mass index s, where the number of meteoroids, the Multinest algorithm. Application of the Multinest dN, having masses between m and m+dm is given by algorithm also allows for fully automated estimates of dN ∝ m−sdm. The mass index plays a crucial role the mass index from radar data. Here we apply this in estimates of meteoroid flux and mass input and is a approach to CMOR data to investigate mass indices powerful constraint for models of the origin and evo- of the sporadic meteoroid complex on daily basis for lution of the meteoroid complex. However, different five consecutive years 2011–2015 (Figure 1). Our best authors use different approaches to fit observed data, estimate for the average debiased mass index for the making results difficult to reproduce and the resulting sporadic meteoroid complex as measured by radar ap- uncertainties difficult to justify. The real, physical, un- propriate to the mass range 10−3 > m > 10−5 g certainties may in some cases be an order of magnitude was s = −2.10 ± 0.08. For comparison, application higher than reported values. of MultiNest to data gathered by the Canadian Au- Here we use the cumulative amplitude distribution tomated Meteor Observatory (CAMO) multi-station of underdense meteor echoes measured by the Cana- optical influx system appropriate to in the 10−1 > dian Meteor Orbit Radar (CMOR) to estimate the me- m > 10−3 g having shower meteors removed pro- teoroid mass index at mm to sub-mm meteoroid sizes. duced s = −2.08 ± 0.08.

Figure 1: Variations of the mass index measured over five consecutive years 2011–2015 by the 29.85 MHz CMOR radar. Color coded dots represent the mass index for each 1◦ solar longitude bin and color coded lines show the moving average with 10◦ window averages. Arrows with labels denote maxima of Arietids (ARI), (SDA), and Geminids (GEM) meteor showers. Meteor head echo climatology at Northern polar latitudes

C. Schult (1), G. Stober (1), J. L. Chau (1) (1) Leibniz Institute of Atmospheric Physics, Rostock University, Kuehlungsborn, Germany ([email protected])

Meteors have been studied with several observation techniques since decades. Until recently, only all sky 120 3 meteor radars and optical camera systems offered the 115 possibility to detect a large number of meteor events 2.5 110 and were able to perform a nearly continuous obser- 2 105 SA NA vation of the Earth’s meteor environment. At present SA High Power Large Aperture (HPLA) radars are the 100 ALL NA 1.5 NT NT Altitude / km

95 log10(meteors) most sensitive meteor detector, but often do not pro- HE AH/HE AH 1 vide continuous measurements. 90

The Middle Atmosphere Alomar Radar System 0.5 (MAARSY) is an HPLA class radar, which is located 85 80 0 in Andenes Northern Norway. MAARSY employs 50 100 150 200 250 300 350 0 50 Day of the year Total / 1000 an active phased array antenna and has a transmitting power of 800 kW. Making use of the interferometric Figure 1: Altitude distribution for the different capabilities we are able to measure the meteor trajec- time of the year (North/South Apex NA/SA, He- tory, the velocity as well as the deceleration. We are lion/Antihelion HE/AH and North Toroidal NT). The going to present quasi-continuous meteor head echo mean ablation height varies for all sources during the observations from the last three years. During this time year over several kilometers due to changes in the we obtained over one million high quality meteor head background atmosphere and the changing in the ele- echoes. vation angle of the source. Based on this data, we derived a meteor climatology of the meteor influx at northern polar latitudes. As an example, Fig. 1 shows the variance of the ablation heights for each day of the year. The mean ablation 5 AH/HE mean: −7.5 heights vary up to 5 km from 97.5 km on day 162 to NA/SA mean: −8.5 102 km on day 323. NT mean: −7.9 High power large aperture radar system have the 4 sensitivity to observe smaller particles than all sky or optical systems. Fig. 2 shows the observed dynami- cal mass distribution for the different main sporadic 3 sources at the point of detection. The statistics indi- cate also that this distribution is very sensitive on the log10(counts) precision of the elevation angle measurement and have 2 to be treated carefully. We present this unique data set, which is also the ba- sis for additional studies on a radar-optical comparison 1 −14 −12 −10 −8 −6 −4 −2 0 and ablation modeling. log10(mass) / kg

Figure 2: Dynamic mass distribution for the different sporadic sources. Meteoroids from the NA/SA com- plex seem to be one order of magnitude smaller than particles from the HE/AH sources. September ε Perseids observed by the Czech Fireball Network in 2013 and 2015

L. Shrbený , P. Spurný Astronomical Institute of the Czech Academy of Sciences ([email protected])

Introduction

During first two hours of observations in the night of 9 September 2013 we recorded a total of 19 bright September epsilon Perseids (SPE). Only a part of them were multi-station fireballs. One SPE fireball was also observed on 6 September 2013 and two bright SPE fireballs were observed on 14 and 18 September 2015 (Fig 1). Autonomous Fireball Observatory (AFO) cameras with large-format sheet film as a detector and one new generation digital autonomous fireball observatory (DAFO) tested at Ond řejov observatory were instruments used in 2013. DAFO cameras were gradually installed on all Czech stations during 2014 and provided multi-station Fig 2 Spectrum of SPE fireball recorded on 14 Sep 2015 data on SPE fireballs in 2015. The spectrum of the SPE fireball (Fig 2) was recorded by digital video camera with diffraction grating with 600 grooves per mm. The video was in progressive scan format with 7.5 frames per second. From the temporal evolution of the spectrum and identification of emission lines of the second (high-temperature) spectrum [2], which is connected with a meteor shock wave (created at the time when the continuous flow regime forms around the meteoroid [3]), we concluded that the beginning of the continuous flow regime occured at the height between 90 and 93 km. We also determined the height of the beginning of the continuous flow regime according to [4] and we come to the same height range between 90 and 97 Fig 1 Very bright SPE Fireball recorded by DAFO at km (the height depends on the method of determination of Czech station Svratouch on 18 September 2015 the mean free path). The spectrum is similar to spectra of

other shower meteors with similar velocity and brightness The 2013 SPE outburst and 2015 SPE fireballs provided and does not show any exceptional or rare features. us with 15 atmospheric trajectories and heliocentric orbits, From the evolution of both persistent trains we found that evolution of two long-lasting persistent trains (one more both trains remained observable for the longest time at the than half an , second about 15 min), and one video height around 90 km and that the maximum horizontal spectrum. These data enabled us to study in much detail shift due to the high-altitude wind was 70 m/s. physical properties and orbital characteristics of the shower. Radiant and orbit

Atmospheric trajectories The mean geocentric radiant of the SPE 2013 outburst The beginning heights range from 100 to 120 km (up to meteors for solar longitude 167.21° is 47.67 ± 0.10°, 140 km for more sensitive DAFO) and approximately 39.54 ± 0.10°. The mean heliocentric orbit of the SPE increase with initial mass of the meteoroid. The terminal 2013 outburst meteoroids has perihelion distance of 0.727 heights range from 75 to 90 km (down to 65 km for AU, eccentricity of 0.992, and inclination of 139°. DAFO) and approximately decrease with initial mass.

Physical properties and persistent train References [1] Ceplecha, Z., McCrosky, R. E., Journal of Geophysical We compared empirical end-height criterion PE Research, Vol. 81, pp. 6257-6275, 1976. č coefficients [1], dynamic pressures at the point of the [2] Borovi ka, J., Planetary and Space Science, Vol. 42, meteoroids fragmentation, light curves, and spectra of pp. 145-150, 1994. č č SPE fireballs and other meteor shower fireballs. The [3] Borovi ka, J., Weber, M., Bo ek, J., WGN, Journal of material of SPE meteoroids is a bit harder than that of the IMO, Vol. 34, pp. 49-54, 2006. Orionids and statistically the same as that of Perseids. [4] Bronshten V. A., D. Reidel Publ. Co., 1983. The instantaneous trail length of faint meteors

E. Stokan, M. Campbell-Brown, P. Brown, J. Aubrey, M. Doubova, S. Sharma, D. Subasinghe The University of Western Ontario ([email protected])

The dustball model postulates that meteoroids are comprised of refractory grains embedded in a volatile 76.1 km matrix [1,2]. As the meteoroid descends in the atmo- sphere, the matrix ablates first, releasing grains that ablate individually. The meteor is expected to develop an instantaneous luminous trail, with a length depen- dent on the grain release rate, as well as the size distri- bution of grains. An example trail is given in Fig. 1, recorded on high-resolution, image-intensified video. Previous efforts to observe faint meteor (down to +8 magnitude) instantaneous trail lengths have yielded values up to 2000 m, but were hampered by low video resolution and signal-to-noise ratio [3,4]. Simultane- ous observations of the instantaneous trail length and meteor light curve can yield information about the size distribution and density of grains comprising the me- teoroid. We discuss measurements of the lengths of faint me- 75.2 km teor (dimmer than 0 magnitude, m < 10−4 kg) instan- 150 m taneous trails, captured in high resolution (< 5 m per pixel) intensified video by the Canadian Automated Figure 1: Snapshots of the instantaneous meteor trail Meteor Observatory (CAMO) [5]. CAMO has been observed on 2016-01-06 07:49:18 UTC with CAMO, collecting meteor observations since April 2010, and a at heights ranging from 76.1 to 75.2 km. The meteor recent statistical analysis on events recorded between had a peak absolute magnitude of +3.1 ± 0.2. Snap- 2010 and 2014 has revealed that about 85 per cent shots are approximately every 10 ms and have inverted show significant trails [6]. The goal of this project is to contrast for visibility. 150 m at the range of the mete- quantify instantaneous trail lengths with an objective oroid has been illustrated at the bottom. and reliable method, such that the grain size distribu- tion of the associated meteoroid may be determined [4] Shadbolt, L., Hawkes, R. L., (1995). Earth, with ablation models. Moon, Planets, 68, 493.

[5] Weryk, R. J., Campbell-Brown, M. D., Wiegert, References P. A., Brown, P. G., Krzeminski, Z., Musci, R., (2013). Icarus, 225, 614. [1] Hawkes, R. L., Jones, J., (1975). MNRAS, 173, [6] Subasinghe, D., Campbell-Brown, M. D., 339. Stokan, E., (2016). MNRAS, 457, 1289. [2] Campbell-Brown, M. D., Borovicka,ˇ J., Brown, P. G., Stokan, E., (2013). A&A, 557, A41, 13pp.

[3] Fisher, A. A., Hawkes, R. L., Murray, I. S., Campbell, M. D., LeBlanc, A. G., (2000). Planet. Space Sci., 48, 911. Luminous Efficiency estimates from the Canadian Automated Meteor Observatory

D. Subasinghe, M.D. Campbell-Brown, E. Stokan University of Western Ontario, Canada ([email protected])

Of the many parameters involved in meteoroid We have selected from our high quality observa- ablation, luminous efficiency, the fraction of kinetic tions the meteor events that show single-body ablation energy released as visible light, is the most uncertain. (that is, events that show minimal fragmentation in Dozens of studies of luminous efficiency have been the narrow-field observations). These events are ap- published using various methods (lab experiments [1]; propriate for use with the classical ablation equations. artificial meteors [2]; simultaneous radar and optical The uncertainty in position measurements for these observations [3]) and the results vary by up to two events is typically around 5 meters. orders of magnitudes; the studies also disagree as to how luminous efficiency varies with meteoroid speed. For each of these high-quality non-fragmenting The luminous efficiency is necessary for determining events, we can use the classical ablation equations to the mass of a meteor, and with widely varying lumi- determine an approximate luminous efficiency. We nous efficiency values, it is difficult to ascertain the will present how sensitive the method is to variations true masses of meteors. This affects measurements of in the atmospheric density, meteoroid density, lumi- meteoroid density and other properties, and meteoroid nous efficiencies that change over time, and shape fac- flux and hazard determinations. tor, using synthetic data from the ablation model of [5]. Preliminary results of this investigation will be Combining classical meteor ablation equations discussed. for photometric and dynamic masses allows us to compute the luminous efficiency, through a combina- tion of observable (atmospheric density; meteoroid References velocity; meteoroid deceleration; luminous intensity) [1] Friichtenicht, J. F., Slattery, J. C., Tagliaferri, E., and estimated (shape factor; drag coefficient; mete- ApJ, Vol. 151, pp. 747 - 758, 1968 oroid density) parameters. This method, however, [2] Ayers, W. G., McCrosky, R. E., Shao, C.-Y., SAO requires very precise deceleration measurements: Special Report, Vol. 317, pp. 1 - 40, 1970 any uncertainty in the position measurements will [3] Weryk, R. J., and Brown, P. G., Planet. Space propagate through to the deceleration values, and Sci., Vol. 81, pp. 32 - 47, 2013 can cause large uncertainties in the final luminous [4] Verniani, F., Smithsonian Contrib. Astrophys., efficiency estimate. This method assumes that the Vol. 8, pp. 141-172, 1965 meteoroid does not fragment, and has been used in the [5] Campbell-Brown M. D., Koschny D., A&A, Vol. past on a single low-altitude Super Schmidt meteor 418, pp. 751 - 758, 2004 [4] .

The Canadian Automated Meteor Observatory col- lects wide-field meteor observations and simultaneous narrow-field observations, the latter with resolutions as precise as 3 meters per pixel. Wide-field observa- tions provide luminous intensity measurements, while narrow-field observations provide high-precision deceleration measurements. The narrow-field obser- vations also provide information on the nature and spread of fragments, if any. Taurids 2015 - spectra and structure diversity by AMOS

J. Toth (1), P. Matlovic (1), R. Rudawska (2), L. Kornos (1) (1) Comenius University in Bratislava, Slovakia, (2) ESA/ESTEC, ([email protected])

Introduction Acknowledgment This work was supported by the grant APVV-0517-12. Predicted outburst of Taurid meteor shower based on [1] was also observed by AMOS cameras and by spectral References camera AMOS-Spec [2] in Slovak Video meteor Network. [1] Asher, D.J. & Clube, S.V.M., Q. J. R. Astron. Soc. 34, More Taurid spectra were obtained during the expedition 481-511, 1993. in Atacama, Chile Nov. 5-13, 2015. The Taurid meteoroid [2] Rudawska, R., Tóth, J., Kalmančok, D., Zigo, P., stream and its source have been studied extensively for Matlovič, P., Meteor spectra from AMOS video system, many years. The stream has been frequently linked with Planetary and Space Science, doi:10.1016/j.pss.2015. short period comet 2P/Encke along with various near- 11.018, 2015. Earth objects [3, 4, 5, etc.] and even two observed [3] Whipple, F.L., The Scienfitic Monthly, 51, 579, 1940. carbonaceous meteorite falls [6, 7]. However, recent [4] Jopek, T.J. & Williams, I.P., MNRAS, 430, 2377, studies show rather skeptical results [8, 9]. 2013. Here we present spectral, dynamical and physical [5] Porubčan, V., Kornoš, L., Williams, I.P., Contribution analysis of Taurid meteor shower from numerous of the Astronomical Observatory of Skalnaté Pleso, 36, observations. Emission line ratios of Fe, Mg, Na are 103, 2006. compared with material parameters and structural [6] Haack, H., Michelsen, R., Stober, G.. et al., Meteoritics characteristics of simultaneously observed Taurid and Planetary Science Supplement, 74, 5271, 2011. meteoroids. We will discuss the similarity of observed [7] Jenniskens, P., Girten, B., Sears, D.. et al., Meteoritics spectral features with chondritic composition, and the and Planetary Science Supplement, 75, 5376, 2012. dispersion of iron and sodium among observed cases. [8] Popescu, M., Birlan, M., Nedelcu, D. A., Vaubaillon, Their dynamical and physical characteristics with possible J., Cristescu, C. P., Astronomy & Astrophysics, 572, implications to parent body(ies) are discussed. A106, 16 pp, 2014. [9] Tubiana, C., Snodgrass, C., Michelsen, R., Haack, H., Böhnhardt, H., Fitzsimmons, A., Williams, I.P., Astronomy & Astrophysics, Volume 584, id.A97, 10 pp, 2015.

Fig 1 Taurid meteor spectra compositions from Chile 2015. Determination of Dust Particle Masses using OSIRIS NAC and WAC Data Esther Drolshagen1, Theresa Ott1, Detlef Koschny2, 4, Carsten Guettler3, Cecilia Tubiana3, Jessica Agarwal3, and Bjoern Poppe1 1 University of Oldenburg, Germany; 2 ESA/ESTEC, Noordwijk, The Netherlands; 3Max-Planck- Institut für Sonnensystemforschung, Göttingen, Germany, 4Chair of Astronautics, TU Munich, Germany. Abstract

The ESA spacecraft Rosetta has been tracking its target, the Jupiter-family comet 67P/Churyumov-Gerasimenko, in close vicinity for over one year. In some dedicated imaging sequences, the two OSIRIS cameras onboard Rosetta, the NAC (Narrow Angle Camera) and the WAC (Wide Angle Camera), took images at the same time.

The aim of this work is to use these double camera data to calculate the dust particles’ mass in the coma of the comet. For that, the distance to camera of the same particle which was found on the NAC images and on a WAC image has to be determined. In the simultaneously taken data, some particles show a shift between the trails seen by NAC and by WAC. With this parallax and the distance between the cameras, the distance to the cameras can be computed. Together with the brightness and movement of the particle, the data yield its mass. For this purpose almost 75 double camera images were investigated. This work presents first results of the ongoing work. {   v     .w!a{  

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Quan-Zhi Ye (1), Peter G. Brown (1) (1) Department of Physics & Astronomy, The University of Western Ontario, London, Ontario, Canada ([email protected])

Extinct comets (ECs) are near Earth objects that appear asteroidal but may have a cometary origins. Earth-approaching ECs may also produce dust dur- ing their final active stages which potentially are de- tectable today as weak meteor showers at the Earth. Identifying ECs is difficult as they are observation- ally indistinguishable from asteroids. Past asteroid- stream searches have produced some possible linkages between asteroids and meteor showers, the most no- table being the Geminids and (3200) Phaethon and the Quadrantids and (196256) 2003 EH1. However, a comprehensive contemporary survey to look for all possible weak streams from the large number of recently discovered ECs which may have displayed weak past activity, including dynamical formation and evolution of early dust trails has yet to be performed. Here we report on the progress of an EC meteoroid stream survey whereby we have identified all EC can- didates whose orbits are such that recent (last several hundred years) dust release would be currently de- tectable at the Earth. We have simulated the evolution of dust trails for all candidate EC-stream objects and generate predictions for the characteristics of the asso- ciated EC shower at Earth. We then perform a cued survey for such streams among the 13 million mete- oroid orbits measured by CMOR since 2002, using a wavelet-based search algorithm with probe sizes tuned to the expected shower characteristics. The search is focused on 408 Earth-approaching asteroids that have dynamical characteristics of comets (or asteroids in cometary orbits, ACOs). For some cases we will also discuss the connection between the meteor data and astrophysical observations of the parent body itself. The resulting possible EC-linked showers detectable by CMOR will be presented and a value for the total active fraction of ECs over the last several centuries estimated. Observations of Asteroid 2003EH1, Possible Parent Body of the Quadrantid Meteoroid Stream

Kasuga, T. (1) and Jewitt, D. (2)

(1) Planetary Exploration Research Center, Chiba Institute of Technology, Japan ([email protected]), (2) Department of Earth, Planetary and Space Sciences and Department of Physics and Astronomy, University of California at Los Angeles, USA

Abstract

The near-Earth asteroid (196256) 2003 EH1 is associated with, and is presumed to be the parent body of, the Quadran- tid meteoroid stream [1,2,3,4,5,6]. Our photometric obser- vations investigate the physical properties of the asteroid and its possible relation to the stream. No evidence for on-going mass-loss is found (Fig. 1). Surface brightness profile at 2.1 AU limits the fractional contribution to the integrated bright- ness by near-nucleus coma to ≤ 2.5 %. We find that the ef- fective nucleus radius is re = 2.00.2 km using the assumed value of an typical for cometary nuclei (pR=0.04). A rotational period of 12.6500.033 hr is derived by fitting the time-resolved R-band photometry (Fig. 2). The photometric range of the lightcurve, ∆mR= 0.44  0.01 mag, indicates Figure 2: The two-peaked rotational light curve has a period an elongated shape having an axis ratio ∼1.5 projected onto Prot=12.6500.033 hr. the sky plane. The colors of the asteroid are consistent with those of C-type asteroids (Fig. 3). The maximum mass loss rate deduced from a model fitted to the profile is . 2.5× 10−2 kg s−1. Water ice can occupy a fraction of the surface −4 no larger than fA . 10 . Current dust production from 2003 EH1 is orders of magnitude too small to supply the mass of the Quadrantid core meteoroid stream (1013 kg) in the 200?500 year dynamical lifetime [1,3,6]. If 2003 EH1 is the source of the Quadrantids, we infer that mass must be delivered episodically, not in steady-state. This work is published in The Astronomical Journal, 150, 152 (10pp), (2015).

Figure 3: Color plots (V − R vs. B − V ) for 2003 EH1 (blue) on weighted mean with those of the Tholen taxo- nomic classes and the Sun (red).

References [1] Jenniskens P., 2004, AJ, 127, 3018. [2] Williams I. P. et al. 2004, MNRAS, 355, 1171. [3] Wiegert P. A. & Brown P., 2005 Icarus, 179, 139. [4] Babadzhanov P. B. et al. 2008, MNRAS, 386, 2271. [5] Jopek T. J., 2011, MmSAI, 82, 310. [6] Abedin A. et al., 2015, Icarus, 261, 100.

Figure 1: The 360 second integrated R-band image of 2003 EH1 taken by Keck-I 10 m on UT 2013 October 2. The 00 00 00 frame size is 40 × 25 . The object has a FWHM of 0.86 , neither coma nor tail is visible. On a possible cometary origin of the object 2015TB145

G.I. Kokhirova, P.B. Babadzhanov, U.Kh. Khamroev (1) Institute of Astrophysics of the Academy of Sciences of the Republic of Tajikistan, Dushanbe, Tajikistan ([email protected])

The Earth-crossing asteroid 2015TB145 was dis- covered on 10 October 2015 and on 31 October 2015 it approached to the Earth at the minimal distance. On the base of obtained radio images of the asteroid, the value of an albedo estimated as p =0.06 and comet- like orbit, it was suggested, that the object is a dead comet. In order to verify the supposition, the orbital evolution of the 2015TB145 was investigated under the perturbing action of major planets for the time in- terval of 100 thousand years. As a result, it was found that one cycle of variations of the argument of perihe- lion is equal to nearly 40 thousand years and during this period the object intersects the Earth’s orbit eight times. Consequently, if the object has a cometary ori- gin, it can be associated with a meteoroid stream pro- ducing eight meteor showers which should be observ- able at the Earth. The features of the predicted meteor showers, theoretically associated with the 2015TB145, were calculated and a search for observable showers identical to predicted ones was realized using all pub- lished catalogues. It turned out, that seven from eight predicted showers were identified with the active ob- servable meteor showers. So, a comet-like orbit, the low value of an albedo and the association with the me- teoroid stream producing identified showers are strong evidences pointing that the 2015 TB145 is really inac- tive comet. A conclusion was made that the poten- tially hazardous object 2015TB145 is very likely ex- tinct nucleus of a parent comet of the revealed mete- oroid stream. General Relativistic Precession in Small Solar System Bodies

A. Sekhar (1, 2), S. C. Werner (1), D. J. Asher (2), J. Vaubaillon (3), M. Hajduková (4), G. Li (5), (1) Centre for Earth Evolution and Dynamics, University of Oslo, Norway ([email protected]), (2) Armagh Observatory, United Kingdom (3) IMCCE, Observatory of Paris, France (4) Astronomical Institute, Slovak Academy of Sciences, Slovakia (5) Harvard-Smithsonian Center for Astrophysics, United States of America

Introduction Discussion

We find that GR precession could play an important One of the greatest successes of the Einstein’s Gen- role in the calculations pertaining to MOID and impact eral Theory of Relativity (GR) was the prediction,[1], forecasts in the case of some small solar system bod- of the precession of perihelion of Mercury. The ies. Previous works, [7][8][9][10][11], have looked expression,[2], to compute this precession tells us that into impact probabilities and collision scenarios on substantial GR precession would occur only if the bod- planets from different small body populations. This ies have a combination of both moderately small per- work aims to find certain sub-sets where GR could ihelion distance (q) and semi-major axis (a). Mini- play an interesting role. Certain parallels are drawn mum Orbit Intersection Distance (MOID) is a quantity between the cases of asteroids, comets and small q me- which helps us to understand the closest proximity of teoroid streams (similar to the one discussed in [12]). two orbits in space. Hence evaluating MOID is crucial to understand close encounters and collision scenarios References better. In this work, we look at the possible scenarios [1] Einstein A. 1915, Preussische Akademie der where a small GR precession in argument of pericentre Wissenschaften, Sitzungsberichte, 831. (ω) can create substantial changes in MOID for small [2] Weinberg S. 1972, Gravitation and Cosmology: bodies ranging from meteoroids to asteroids. Principles and Applications of the General The- ory of Relativity, Wiley, New York. [3] Valsecchi G.B. 2006, Lect. Notes Phys., 682, 145. Analytical Approach and Numeri- [4] Valsecchi G.B., Milani A., Gronchi G.F. , Ches- ley S.R. 2003, Astron. Astrophys., 408, 1179. cal Integrations [5] Naoz, S., Kocsis, B., Loeb, A., Yunes, N. 2013, ApJ, 773, 187. [6] Li, G., Naoz, S., Kocsis, B., Loeb, A. 2014, ApJ, Previous works, [3][4], have looked into neat analyt- 785, 116. ical techniques to understand different collision sce- [7] Werner S. C., Ivanov B. A., 2015, Exogenic Dy- narios and we use those standard expressions to com- namics, Cratering and Surface Ages. In: Ger- pute MOID analytically. We find that the nature of ald Schubert (editor-in-chief), Treatise on Geo- this function is such that a relatively small GR preces- physics, 2nd edition, Vol. 10, Oxford: Elsevier, sion (∆ω ∼ 10−1 degrees/10 kyr) can lead to dras- 327. tic changes in MOID values (dMOID ∼ 10−3 AU) [8] Asher D. J., Bailey M. E., Emel’yanenko V. V., depending on the initial value of ω. Numerical inte- 1999, MNRAS, 304, L53. grations were done with package MERCURY incor- [9] Vaubaillon J., Lamy P., Jorda L., 2006, MNRAS, porating the GR code to test the same effects. Numer- 370, 1841. ical approach showed the same interesting relation- [10] Sekhar A., Asher D. J., 2014, Meteorit. Planet. ship (as shown by analytical theory) between values Sci., 49, 52. [11] Hajduková, M., Rudawska, R., Kornos, L., Tóth, of ω and the peaks/dips in MOID values. Previous J. 2015, P&SS, 118, 28. works, [5][6], have shown that GR precession sup- [12] Fox K., Williams I.P., Hughes D.W. 1982, MN- presses Kozai oscillations and this aspect was verified RAS, 199, 313. using our integrations. We find an overall agreement between both analytical and numerical methods. Analysis of the January 7, 2015, superbolide over Romania

J. Borovička (1), P. Spurný (1), V. I. Grigore (2), J. Svoreň (3) (1) Astronomical Institute, Czech Academy of Sciences, Ondřejov, Czech Republic ([email protected]), (2) SARM - Romanian Society for Meteors and Astronomy (3) Astronomical Institute, Slovak Academy of Sciences, Tatranská Lomnica, Slovakia

Introduction Analysis

An extremely bright illuminated the skies over We used two images (one digital and one analog) from Romania on January 7, 2015, 1:06 UT (3:06 am local Stará Lesná and five video records taken at various sites in time). Despite the late night time, the bolide caused wide Romania (showing directly the bolide) to derive the attention in the country, including news media. A number trajectory and velocity. The videos were calibrated in situ of videos, mostly from security cameras, showing the by taking stellar images at the positions of the video intense illumination lasting for about two seconds, were cameras following the method of [2] and/or by taking published on the Internet. Fortunately, the bolide was also images containing bright celestial objects (Moon, Jupiter) photographed, close to horizon, by two cameras of the directly by the original video cameras at known times. All European Fireball Network (EN) located in Stará Lesná, used videos were from security cameras with low Slovakia. Part of the bolide can be seen even on the photo resolution but with fixed and well known positions. There from station Lysá hora, Czech Republic, where the bolide is also a high resolution video taken by a dashboard was more than 700 km distant. In addition, good camera from moving car (Fig. 1), which shows more radiometric light curve was obtained by the EN cameras. details, but could not be calibrated. Superbolides are rare events with limited scientific coverage. Most of them occur in remote areas Results and are only observed by infrasound stations or US Government Sensors [1] over large distances and with The bolide was remarkable by the fact that it terminated limited accuracy of trajectory, velocity and other by a bright broad flare covering the heights 47 – 39 km. parameters. Here we take advantage of the existing data The maximum brightness was reached at 42.8 km. Only and study in detail the January 7 superbolide. The results one small fragment, seen only on the high resolution can be compared with the US Government Sensors data video, emerged from the flare and disappeared at a height for this superbolide as given in [1]. of about 36 km. These heights are quite high for such a large body. Using the energy from [1], the initial mass of the meteoroid was computed to be 4000 kg. The low penetration ability and intensive atmospheric fragmentation suggest that the body was not a solid rock or iron but a weaker material. Nevertheless, we cannot confirm the purely cometary orbit from [1]. The pre- impact orbit had in fact the Tisserand parameter relative to Jupiter close to 3.0. If some material reached the ground, it was only in the form of small fragments or dust. Brief meteorite searches and interviews with local people were performed in the suspected impact area to the west of the city of Focsani on March 26 and on April 3, 2015, with negative results. The model of atmospheric fragmentation and a comparison with other superbolides caused by weak bodies, such as the Maribo meteorite fall and the EN311015 Taurid bolide, will be presented in the talk. These studies will provide information about the structure of meter-sized bodies composed from other materials than ordinary chondritic.

References Fig 1 Two frames from the dashboard video taken by Adrian Pascale in Fierbinti showing the bolide in flight (top) and [1] Brown, P., Wiegert, P., Clark, D., Tagliaferri, E., during the maximum luminosity (bottom). Source: Icarus, Vol. 266, pp. 96-111, 2016. youtube.com [2] Borovička J., Proceedings IMC 2013, Poznań, Poland, pp. 101-105, 2014. A preliminary comparison of MAARSY head echo measurements simultaneously detected with optical instrumentation

P. Brown (1), G. Stober (2), C. Schult (2), Z. Krzeminski (1)., W. Cooke (3) and J.L. Chau (2) (1) Department of Physics and Astronomy, University of Western Ontario, London, Ontario, N6A 3K7 CANADA ([email protected]), (2) Leibniz Institute of Atmospheric Physics, Rostock University, Keuhlungsborn, Germany, (3) NASA Meteoroid Environment Office, Marshall Space Flight Center, Huntsville, Alabama 35812

speed determination) allow for an estimate of The measurement of fundamental meteoroid astrometric consistency in trajectory. properties, such as mass, bulk density and We find a median radiant and speed difference of chemistry from meteor observations is difficult. 1.4 deg and 0.3 km/s, respectively, between head Arguably the most fundamental of these echo and optical meteor trajectory estimates. On characteristics, meteoroid mass, remains average the radar head echoes show initial particularly challenging, despite its obvious detections ~2km higher than optical first importance to almost all meteor studies. Poorly detection, but the optical trajectory ends on constrained luminous, ionization and acoustic average ~2 km lower than head echoes detectable efficiencies may lead to order of magnitude to the radar. uncertainties in meteoroid mass. Inference of Initial photometric, ionization and mass mass from deceleration measurements are comparisons will be presented and systametic complicated by fragmentation and require high differences between optical and radar head echo precision metric data. measurements noted to date will be highlighted Absolute mass estimates and technique specific together with possble explanations. uncertainites can best be validated through multi- instrumental, simultaneous measurements of the same events. In this study we summarize the initial results of a two year (Sept, 2014 – April, 2016) campaign of simultaneous optical and head echo measurements from Andoya, Norway. Continuous radar head echo observations by the Middle Atmosphere Alomar Radar System (MAARSY) are correlated with automated meteor optical measurements from two stations. Each optical station consists of a wide field (15x11 degrees) NTSC video frame rate camera co-aligned with a narrow-field (6 circular Figure 1. A video stack showing an example field of view) image intensified digital video wide-field optical Quadrantid (peak R-magnitude system operating at 50 fps. The former detects +3) detected also by MAARSY on Jan 4, 2016. meteors to peak R magnitude +4, the latter to V The optical trail is indicated as a series of black magnitudes of +9. The optical systems overlap a dots (one per video field) in this case moving common atmospheric volume in the MAARSY from the center of the field of view to the lower main beam at 95 km altitude. left of the image. The equivalent plane of sky Over 200 events were simultaneously detected as location per pulse measured from MAARSY head echoes by MAARSY and one or more interferometry of the head echo is shown as a optical cameras, based on a comparison of series of green points. The inner blue circle shows absolute timing and direction between optical and the location of the half power point of the main radar detected meteors. Reduction of a subset of beam of MAARSY, while the outer purple circle 66 of the highest quality simultaneous events shows the location of the first null of the the radar (where both optical / radar data provide beam. Here the head echo is visible earlier (to the independent trajectory solutions and the upper right) than the first optical registartion of intersection geometry for optical stations is good the meteor. and trail lengths are long enough for reliable Ablation of small iron meteoroids – first results

D. Čapek , J. Borovi čka Astronomical Institute of the Czech Academy of Sciences, Ond řejov, Czech Republic ([email protected])

Introduction

Among the video meteors, there is a population which is characterized by low speeds, asteroidal orbits, low beginning heights, short duration, and quick increase of brightness [1]. In accordance with spectral observations it has been suggested, that they are caused by small iron meteoroids. The shape of the light curves is very unusual. It has a quick increase of brightness with maximum near the beginning of its luminous trajectory. Such shape is hard to explain by classical single body ablation theory and also by fragmentation of parent meteoroid. The hypothesis is that the unusual ablation process is caused by thorough preheating of an iron meteoroid due to high thermal conductivity, melting of the whole volume of the body, and rapid ablation of the thus formed liquid iron droplet [2].

Model

To check our hypothesis, we developed a numerical model which mathematically describes the above mentioned phenomena and gives theoretical predictions for the light curves.

The model assumes iron spherical meteoroids with temperature – dependent thermal parameters. Temperature field has radial symmetry and it is determined numerically by solving the heat diffusion equation. On the surface, the incoming energy (in free molecular flow regime) is balanced by heat conduction into the body, thermal radiation and melting or fusion if sufficient temperature is reached. There are also one or two moving boundaries (solid/melt and melt/vapor) if the phase change occurs. The resulting theoretical light curve is determined on the basis of the amount of ablated material.

Results

We will show first results of our model, especially the comparison of the synthetic light curves (i.e. beginning heights and the shape) with the observed ones for several model parameters. Finally, we will determine if the ablation of iron meteoroids (liquid iron droplet, as described above) is able to describe the observed meteors.

References [1] Campbell-Brown, M., Planetary and Space Science, Vol. 118, pp. 8–13, 2015. [2] Borovi čka, J. et al., Icarus, Vol. 174, pp. 15-30, 2005. JEM-EUSO and its pathfinder Mini-EUSO to observe meteors from the International Space Station

A. Cellino (1), M. Bertaina (2) for the JEM-EUSO Collaboration (1) INAF - Torino Astrophysical Observatory, and INFN Torino ([email protected]), (2) University of Torino and INFN Torino ([email protected])

Abstract fainter in the best possible conditions. Taking ad- vantage of its large FOV and high detection rate, JEM-EUSO should be able to record a statisti- Since several years an International Collabora- cally significant flux of meteors, including both tion involving several research institutes located sporadic ones, and events produced by different in 16 countries of 4 different continents (Europe, meteor streams. Unaffected by adverse weather Asia, America and Africa) has been working on conditions, which limit the effectiveness of ground- the development of the JEM-EUSO mission to be based meteor observation networks, JEM-EUSO carried out from the International Space Station can also become a very important facility for the (ISS). The project has evolved with time, and it detection of bright meteors and fireballs, as these includes now also a smaller, pilot mission, named events can be detected even during periods of very Mini-EUSO, supposed to fly in advance before the high sky background. Therefore, monitoring of proposed main mission. The main goal of JEM- bright events will always be active, nicely comple- EUSO is the detection of Ultra High Energy Cos- menting current ground-based activities like the mic Rays (UHECR, 5×1019 −1021 eV), by means French FRIPON program, whereas the detection of a dedicated refractive telescope (2.5 m of aper- of faint meteors requires more optimal observing ture) equipped with an UV detector on its focal conditions. In the case of bright events, moreover, plane, covering a wavelength range between 290 exhibiting a much longer signal persistence with and 430 nm, positioned in one of the modules of respect to faint meteors, our preliminary simula- the ISS in such a way as to carry out Nadir obser- tions show that it should be possible to exploit the vations from an height of about 400 km above sea movement of the ISS itself and derive at least a level on a full field ov view (FOV) of ∼ 60◦. In rough 3D reconstruction of the meteor trajectory. this way, the instrument will detect the secondary This would allow the position and velocity vectors light emissions induced by cosmic rays in the at- to be computed instead of a simple 2D projection mosphere (fluorescence light and Cerenkov). This of the motion. mission design also makes it possible the detec- It is interesting to note that the observing strat- tion of a variety of transient luminous events in egy developed to detect meteors may also be ap- the atmosphere, including meteor phenomena. plied to the detection of nuclearites, exotic parti- Mini-EUSO, as a pathfinder mission for JEM- cles whose existence has been suggested by some EUSO, will use the same technologies of JEM- theoretical investigations. They are expected to EUSO but with smaller lenses (25 cm diameter), a move at higher velocities than meteoroids, and to coarser spatial resolution (5 km instead of 500 m) ◦ exhibit a wider range of possible trajectories (in- and smaller FOV ∼ 40 . Mini-EUSO, a currently cluding particles moving toward the zenith after approved project of ASI and ROSCOSMOS, will crossing the Earth), but still at speeds that can be located inside the ISS, looking in the Nadir be considered slow for JEM-EUSO. The possible direction from the Russian Service Module UV detection of nuclearites greatly enhances the sci- transparent window. entific rationale behind the JEM-EUSO mission. Our preliminary analysis shows that JEM- Currently, since the approval of the pilot Mini- EUSO should be able to detect meteors, in EUSO, we are carrying out simulations aimed at favourable conditions of dark background, down assessing its performance for meteor studies. to magnitudes between 5 and 6, or possibly even Analysis of different methods used to compute meteors orbits

A. Egal (1), P. Gural (2), J. Vaubaillon (1), F. Colas (1), W. Thuillot (1) (1) IMCCE, 77 av. Denfert Rochereau, 75014 Paris, France (2) Samantha Drive, Sterling, VA 20164-5539,USA ([email protected])

Despite of the development of the cameras net- References works dedicated to the observation of meteors, there is still an important discrepancy between the [1] Ceplecha, Z., Geometric, dynamic, orbital, measured orbits of meteoroids computed and the and photometric data on meteoroids from theoretical results. The gap between the observed and photographic records, Astronomy & Astro- theoretic semi-major axis of the orbits is especially physics,1987. significant. An accurate determination of the orbits of meteoroids largely depends on the computation [2] Borovicka, J., The comparison of two methods of the pre-atmospheric velocities. It is therefore of determining meteor trajectories from pho- imperative to dig out how to increase the precision of tographs. Bulletin of the Astronomical Institutes the measurements of the velocity. of Czechoslovakia, 1990. [3] Gural, P., A new method of meteor trajectory de- In this work, we perform an analysis of different termination applied to multiple unsynchronized methods currently used to compute the velocities and video cameras, Meteoritics and Planetary Sci- trajectories of the meteors. They are based on the ence,2012 intersecting planes method developed of Ceplecha (1987), the least squares method of Borovicka (1990), and the multi-fit parameterization method published by Gural (2012). The only way to objectively compare the performances of these techniques is to apply them to well known meteors. We therefore simulate realistic meteors to perform this analysis. Some of them are built following the propagation models studied by Gural (2012), and others created by numerical integrations using the Borovicka et al. 2007 model. In order to reproduce the meteors recorded by the CABERNET cameras, an analysis of the measurement error on the location of the centroids in the images is conducted. Once the simulated meteors are created, we test different optimization techniques to perform the multi-fit parameterization and pick the most suitable one.

We will present the results of this analysis as well as their limitations. We also investigate the influence of the geometry of the trajectory on the result. Improving Photometric Calibration of Meteor Video Camera Systems

Steven Ehlert (1), Aaron Kingery (2), William Cooke (3) (1) Qualis Corporation, Jacobs ESSSA Group ([email protected]), (2), ERC Corporation, Jacobs ESSSA Group, (3) Meteoroid Environment Office, NASA Marshall Space Flight Center

Introduction 2 Laboratory Tests of Camera Linearity Current optical observations of meteors are commonly limited by systematic uncertainties in photometric cal- Accurate calibration of meteor photometry demands ibration at the level of ∼ 0.5 mag or higher. Future im- a robust understanding of the camera linearity in or- provements to meteor ablation models, luminous effi- der to properly compare the fluxes of bright and faint ciency models, or emission spectra will hinge on new meteors or meteors detected in two cameras indepen- camera systems and techniques that significantly re- dently. We discuss a simple, inexpensive laboratory duce calibration uncertainties and can reliably perform experiment that quickly and accurately samples the re- absolute photometric measurements of meteors. sponse curve of a video camera which has been vali- In this talk we discuss the algorithms and tests dated against independent tests in NASA’s video cal- that NASA’s Meteoroid Environment Office (MEO) ibration laboratory. These tests show precisely how has developed to better calibrate photometric measure- the response of a standard meteor video camera varies ments for the existing All-Sky and Wide-Field video as the gain and gamma settings are adjusted across its camera networks as well as for a newly deployed entire dynamic range. four-camera system for measuring meteor colors in Johnson-Cousins BVRI filters. In particular we will emphasize how the MEO has been able to address two 3 Testing and Performance long-standing concerns with the traditional procedure, Applying these new methods to new and existing data discussed in more detail below. enable video photometry of unsaturated meteors accu- rate to ∼ 0.10 mag. A large component of this uncer- tainty arises from deficiencies in our bandpass model- ing. Crucially, there is no evidence for any additional 1 Photometry in an Arbitrary systematic errors or uncertainties that depend on either Bandpasses the magnitude or the color of the reference stars. We will conclude by discussing potential improvements to these methods in the future. The All-Sky and Wide-Field camera networks are sen- sitive to a significantly broader range of wavelengths than a typical Johnson or Sloan filter. Subsequently calibration models that determine zero-points of refer- ence stars in an unfiltered video camera relative to ob- servations taken in a standard astronomical filter will be subject to large color terms that are not accounted for. In order to circumvent the need for large and un- certain color terms, we have used the SAO J2000 cat- alog to create a network of fully calibrated reference stars in the camera response band. This method can be applied to an arbitrary bandpass and enables direct calculations of the meteor flux in physical units. The Southern Argentina Agile Meteor Radar (SAAMER): A platform for comprehensive meteor radar observations and studies

D. Janches1, P. Pokorny2, J. Hormaechea3, P. Brown2, J. Vaubaillion4, R. Michell5, N. Swarnalingam6, D. Fritts7 and C. Brunini8

1. GSFC/NASA, Greenbelt, MD, USA 2. University of Western Ontario, London ON, Canada 3. Estacion Astronomica Rio Grande, Tierra del Fuego, Argentina 4. IMCEE, Paris, France 5. University of Maryland-College Park, Greenbelt MD, USA 6. Catholic University of America, Greenbelt MD, USA 7. Gats, Inc., Boulder, CO., USA 8. Dept. of Astronomy and Geophysics, University of La Plata, La Plata, Argentina

The Southern Argentina Agile Meteor Radar (SAAMER) is a new generation system deployed in o Rio Grande, Tierra del Fuego, Argentina (53 S) in May 2008. SAAMER transmits 10 times more power than regular meteor radars, and uses a newly developed transmitting array, which focuses power upward instead of the traditional single-antenna-all-sky configuration. The system is configured such that the transmitter array can also be utilized as a receiver. The new design greatly increases the sensitivity of the radar enabling the detection of large number of particles at low zenith angles. The more concentrated transmitted power enables additional meteor studies besides those typical of these systems based on the detection of specular reflections, such as routine detections of head echoes and non-specular trails, previously only possible with High Power and Large Aperture radars. In August 2010, SAAMER was upgraded to a system capable to determine meteoroid orbital parameters. This was achieved by adding two remote receiving stations approximately 10 km away from the main site in near perpendicular directions. The upgrade significantly expands the science that is achieved with this new radar enabling us to study the orbital properties of the interplanetary dust environment. Because of the unique geographical location, the SAAMER allows for additional inter hemispheric comparison with measurements from Canadian Meteor Orbit Radar, which is geographically conjugate. Initial surveys show, for example, that SAAMER observes a very strong contribution of the South Toroidal Sporadic meteor source, of which limited observational data is available. In addition, SAAMER offers similar unique capabilities for meteor showers and streams studies given the range of ecliptic latitudes that the system enables to survey. It can effectively observe radiants from the ecliptic south pole to approximately 30°N, and thus enable detailed study of showers at high southern latitudes (e.g July Phoenicids or Puppids complex), which are unobservable from the CMOR’s location. To date about 30 new showers have been identified in SAAMER’s dataset which mostly have radiants within the South Toroidal region. Finally, SAAMER is ideal for the deployment of complementary instrumentation in both, permanent and campaign, operational mode. Results from various radar meteor investigations as well as radar/optical observation campaign will be presented in this paper as well a summary of current upgrades underway which include the addition of a third remote receiving station as well as a chain of all-sky cameras.

The re-entry of artificial meteoroid WT1190F

M. S. Odeh (2), P. Jenniskens (1) (1) International Astronomical Center, Abu Dhabi, United Arab Emirates, (2) SETI Institute, Mountain View, USA ([email protected]).

that the object was rapidly tumbling with a period of about Introduction 1.5-s. Weather updates showed high clouds in the area of impact, with areas of low cloud ceiling drifted through. In the near future, it is likely that a 3-m to 7-m sized The aircraft path was timed to enter one of these areas at asteroid will be detected in space with sufficient warning the time of re-entry. The sky cleared and the re-entry was time for observers to be able to travel to the area of well observed. atmospheric entry and study the manner in which the asteroid breaks apart. With good characterization of the asteroid before impact, this could provide valuable ground truth for high-fidelity models of asteroid impacts.

Observations

A great opportunity to practice such an observing campaign arose on October 23, 2015, when a space debris object was detected on an eccentric orbit and predicted to impact Earth over the Indian ocean near the coast of Sri Lanka six weeks later. Now named WT1190F, this space debris object entered Earth's atmosphere near local noon Figure 1. Re-entry of WT1190F in a wide-angle view. on Friday November 13, with an entry speed of 10.61 The object moved from upper left to lower right. km/s, relative to the atmosphere at 100 km altitude, and an entry angle of 20.6º. These circumstances are more similar The artificial meteor was first detected at 73-km altitude. to those of asteroid impacts than to most other space It fluctuated in brightness with a period of 1.5-s. debris re-entries. WT1190F first lost several fragments starting at 60.0 (±2.5) km. Two of those had nearly identical ballistic The International Astronomical Center in Abu Dhabi and coefficients and travelled down side-by-side. The object the United Arab Emirates (UAE) Space Agency chartered broke in two at 55.8 km. The lower fragment disrupted a commercial G450 aircraft to observe this daytime re- further at 47.2-km altitude, at which time an emission entry. The aircraft was instrumented by an observing team spectrum was measured showing TiO bands and an from Dexter-Southfield School and Embry-Riddle intermittent hydrogen line. Two surviving pieces of the Aeronautical University, a team from the Institute for upper fragment were tracked down to 33 km altitude Space Systems of the University of Stuttgart, and by where they left the field of view. teams from the SETI Institute, the UAE Space Agency and the International Astronomical Center. In part based on these observations, the leading candidate for the identity of WT1190F is the Trans-lunar Injection Cameras deployed included a Red EPIC movie camera Stage of the , a past NASA mission that equipped with a 200-mm focal length lens for high spatial was directed from Ames Research Center. Much resolution imaging, a second movie camera slightly out of information about this vehicle is in the public domain and focus for photometry, two Prosilica monochrome efforts are underway to use the WT1190F reentry spectrographic cameras for measuring emission observations to calibrate satellite re-entry breakup models. signatures, a series of wide angle filtered Watec WAT902 In the future, similar work is envisioned in the context of H2 Ultimate cameras for photometry, a wide angle Sony asteroid impact fragmentation. 7αS digital still camera for early detection, a Lumenera monochrome camera with small field of view for fragment References tracking, and a miniature Echelle spectrograph with fiber- fed collection optics for high resolution spectroscopy. [1] Jenniskens, P., Albers, J., Koop, M., Odeh, M. S., Al- Noimy, K., Al-Remeithi, K., Al Hasmi, K., Dantowitz, R. Results F., Gasdia, F., Löhle, S., Zander, F., Hermann, T., Farnocchia, D., Chesley, S. R., Chodas, P. W., Park, R. S., Results were presented in [1]. In the days leading up to the Giorgini, J. D., Gray, W. J., Roberston, D. K., Lips, T., entry, the trajectory was refined and updates for the AAIA Science and Technology Forum and Exposition impact location and time were provided to the observing (SciTech 2016), 4-8 Jan. 2016, San Diego, CA. Paper team. Observations in the hours before impact showed AIAA-2016-0999. (See also: http://impact.seti.org) Determination of the Meteor Limiting Magnitude

A. Kingery (1), R. Blaauw (2), W. J. Cooke (3) (1) ERC / Jacobs ESSSA Group / NASA Meteoroid Environment Office, (2) All Points / Jacobs ESSSA Group / NASA Meteoroid Environment Office, (3) NASA Meteoroid Environment Office

Introduction magnitude distribution of the stars that were and were not detected is then examined to find the limiting stel- The limiting meteor magnitude of a meteor camera lar magnitude. This is converted to a meteor limiting system will depend on the camera hardware and soft- magnitude in a fashion similar to that of Hawkes [1], ware, sky conditions, and the location of the meteor the details of which will be discussed. radiant. Some of these factors are constants for a given meteor camera system, but many change between me- teor shower or sporadic source and on both long and short timescales. Since the limiting meteor magnitude ultimately gets used to calculate the limiting meteor mass for a given data set, it is important to have an un- derstanding of these factors and to monitor how they change throughout the night, as a 0.5 magnitude uncer- tainty in limiting magnitude translates to a uncertainty in limiting mass by a factor of two.

NASA Widefield Meteor Camera Network

There are four widefield cameras at two sites in north- Figure 1: Limiting stellar magnitude for a widefield ern Alabama, spaced 32 km apart. The primary pur- meteor camera throughout a night. pose of the system is to automatically compute the flux of mm-sized meteoroids from any active showers or sporadic sources via algorithms which run daily. The need to autonomously compute fluxes each morning References requires an auxiliary program to determine the change [1] Hawkes, R. L., Mason, K. I., Fleming, D. E. B., in limiting magnitude for each camera throughout the & Stultz, C. T. 1993, Proceedings of the Interna- night. This program examines images from each sta- tional Meteor Conference, 11th IMC, Smolenice, tion every 10 minutes in order to measure how the Slovakia, 1992, 28 limiting magnitude changes throughout the night and from camera to camera (figure 1).

Discussion

We will discuss our method for determining the limit- ing stellar magnitude. A star catalog is used to deter- mine which stars brighter than magnitude 7 are in the field of view, and aperture photometry is performed on these stars for each image. The signal to noise is calculated and compared to a threshold value. The Experimentation and numerical simulation of meteoroid ablation

L. Limonta , S. Close Stanford University Department of Aeronautics and Astronautics ([email protected])

Abstract meteoroids whose light curve/radar detection indicates the presence of differential ablation [3]. When a meteoroid enters into Earth’s atmosphere, it ablates and forms plasma that is deposited both behind References and immediately around the meteoroid. The proper- ties of this plasma are determined by the meteoroid’s [1] L. Carter and J. Forbes. Global transport and lo- size, velocity and composition. These plasmas can be calized layering of metallic ions in the upper at- used to determine fundamental meteoroid properties, mosphere. In Annales Geophysicae, volume 17, as well as understanding the impact of meteoroids on pages 190–209. Springer, 1999. the upper atmosphere [1, 2]. In order to probe meteoroid properties, we investi- [2] J. Grebowsky, R. Goldberg, and W. Pesnell. Do gate the ablation process by combining data from high- meteor showers significantly perturb the iono- power large aperture radars and optical instruments sphere? Journal of Atmospheric and Solar- with modeling. We developed a two dimensional nu- Terrestrial Physics, 60(6):607 – 615, 1998. merical model taking into account pyrolysis, surface [3] D. Janches, L. P. Dyrud, S. L. Broadley, and recession, and thermal non-equilibrium between the J. M. C. Plane. First observation of micromete- body and the surrounding flow. The surface energy oroid differential ablation in the atmosphere. Geo- balance condition is solved with a moving grid based physical Research Letters, 36(6):n/a–n/a, 2009. on universal meshes [4] to calculate the shape change ISSN 1944-8007. L06101. due to surface recession. The governing equations are discretized with a finite volume approximation in a [4] R. Rangarajan and A. J. Lew. Universal Meshes: body-fitted coordinate system. A new paradigm for computing with nonconform- Using our numerical model, we explore the effect ing triangulations. ArXiv e-prints, Jan. 2012. of size and composition on time of flight of meteoroid events observed via radar and optical instruments dur- ing an experimental campaign in Alaska. From our analysis we can determine at what combination of size, shape and composition a multi dimensional character- ization of the phenomenon matches the simple one di- mensional ablation model. Our results indicate that for fast moving meteors with higher than 5 our numerical model and the 1-d single parameters are in agreement. As the apparent magnitude and velocity decreases, the size estimate - for a given composition - increasingly diverges, up to 40 % for metallic meteoroids. When considering rotating objects, whenever the model con- verged to a solution, the 1-d ablation case severely over-estimates the size (and hence masses) of the de- tected object. In addition our multi-composition con- centric shell model seems to replicate the behaviour of Effects of meteor head plasma distribution on radar cross sections and derived meteoroid masses

R. A. Marshall (1), S. Close (2), P. Brown (3), Y. Dimant (4) (1) University of Colorado Boulder, United States ([email protected]); (2) Stanford University, United States; (3) University of Western Ontario, Canada; (4) Boston University, United States

Introduction frequency. This provides a direct estimate of the me- teor plasma size from a given RCS measurement. Next we investigate the effect of the assumed The problem of determining the meteoroid mass flux plasma distribution. We relax that assumption of a input to Earth’s atmosphere has persisted for decades Gaussian or parabolic exponential distribution and ex- [1]; two orders of magnitude separate the high and low plore different distribution shapes, including a new ends of the commonly-cited estimates. These differ- distribution derived from analytical calculations of ences arise due to different observational methods, but meteor ablation; we call this the Dimant distribution. also due to a large number of uncertainties in assumed Comparing the different calculated RCS from these parameters for each method. different distributions to three-frequency head echo We focus herein on estimates derived from meteor data from the CMOR radar, we show that the Dimant head echoes observed with high-power, large-aperture distribution provides the best fit to the data. However, (HPLA) and other radars. Meteor head plasma and given uncertainties in the data, we cannot conclude radar cross section (RCS) are regularly detected by that any distribution is the most valid. In addition, we these ground-based radars. However, because of the show that the choice of distribution assumed can alter plasma nature of the meteor head, the relationship be- the resulting line density by an order of magnitude for tween the measured RCS and the meteor plasma pa- the same data. We thus show that the in addition to µ rameters is not straightforward. Close et al. [2] and and β above, the line density q is similarly difficult to others relate the meteor head RCS to the electron line ascertain, even with state-of-the-art measurements of density q in the meteor, and then relate the line den- the radar cross section. sity to the meteoroid mass as qvµ = βdm/dt. It is assumed that the velocity v is measured, and the mean molecular mass µ is assumed. The ionization potential References β is summarized by [3] as a function of velocity, but is also a function of composition. The line density q is [1] J. M. C. Plane, “ in the earth’s at- thus left to be determined. mosphere† cosmic dust in the earth’s atmosphere† In this paper, we present numerical calculations to cosmic dust in the earth’s atmosphere,” Chem. relate the meteor head plasma distribution to the RCS; Soc. Rev., vol. 41, pp. 6507–6518, 2012. the line density q is trivial to compute from the dis- [2] S. Close, M. Oppenheim, S. Hunt, and A. Coster, tribution. We use a forward model of radar scatter- “A technique for calculating meteor plasma den- ing from meteor plasma using a finite-difference time- sity and meteoroid mass from radar head echo domain (FDTD) model of the electromagnetic wave scattering,” Icarus, vol. 168, no. 1, pp. 43–52, interaction with the plasma. This model computes the 2004. meteor head RCS for a given meteor plasma distribu- tion, specified with a peak plasma density and a char- [3] M. D. Campbell-Brown, J. Kero, C. Szasz, acteristic size. We then relate measured RCS values A. Pellinen-Wannberg, and R. J. Weryk, “Pho- to the input size and density parameters to better char- tometric and ionization masses of meteors with si- acterize the meteor plasma. We present simulation re- multaneous eiscat uhf radar and intensified video sults that show that the RCS is directly related to the observations,” Journal of Geophysical Research: overdense meteor area; that is, the area of the meteor Space Physics, vol. 117, no. A9, 2012, A09323. inside which the plasma frequency exceeds the radar A reliable methodology to determine fireball terminal heights

M. Moreno-Ibáñez (1,2), M. Gritsevich (2,3), J.M. Trigo-Rodríguez (1) (1) Institute of Space Sciences (CSIC-IEEC), Campus UAB, Carrer de Can Magrans, s/n E-08193 Cerdanyola del Vallés, Barcelona, Spain ([email protected]). (2) Finnish Geospatial Research Institute, Geodeetinrinne 2, FI-02431 Masala, Finland. (3) Institute of Physics and Technology, Ural Federal University, 620002 Ekaterinburg, Russia

Introduction calculations [5].

Previous studies [1, 2] have proved the importance of terminal heights in order to properly characterize fireball flight properties and their degree of atmospheric penetration. However, despite ablation and drag processes associated with atmospheric entry of meteoroids have been widely studied, little attention was devoted to interpret the measured fireball terminal height. This key parameter also provides clues on the bulk physical properties of the meteoroids and, combined with the entry velocity and slope, we can state the deceleration experienced by the meteoroid during the atmospheric flight and thus, the ablation and dynamic pressure held.

Mathematical Formulae and Results

The classical way of resolving the equations of motion requires knowing beforehand a set of properties and physical variables that we cannot obtain accurately enough with ground-based observations. Alternatively, by Fig.1 Observed (MORP) vs. calculated terminal heights. A line using scale laws and dimensionless variables another representing equal values has been plotted. approach can be introduced. The unknown values of the meteoroid’s atmosphere flight motion equations are Conclusions gathered into two new variables α (ballistic coefficient) and β (mass loss parameter), e.g. [3, 4]. The analytical The used parameterization allows describing in detail the solution of these equations (using dimensionless meteoroid trajectory in the atmosphere. Besides, new variables) leads to: classifications can be set using these parameters which may not be biased by previous assumptions on meteoroid’s properties. Furthermore, this methodology can speed up the study of the still large amount of archived data available and of the many new meteor registrations to come. Finally, a better knowledge of these parameters could get Where, clues on the ability of meteoroids to penetrate into the terrestrial atmosphere and to quantify their capability of being a source of impact hazard for life on Earth.

Several simplifications of these equations are admitted References and studied [5]. We prove that using the results recently [1] Ceplecha, Z., and McCrosky, R.E., J. Geophys. obtained in [6] and, suggesting a shift along parameter β, Res.,Vol. 81, pp.6257-6275, 1976. leads to a higher agreement between observed and [2] Wetherill, G.W., and Revelle, D.O., Icarus, Vol. 48, pp. calculated terminal height values: 308-328, 1981. [3] Stulov, V.P., Appl. Mech. Rev., Vol. 50, pp. 671-188, 1997. [4] Gritsevich, M., and Koschny, D., Icarus, Vol. 212 (2), pp 877-884, 2011. Results are shown in Fig.1. Despite the small spread in [5] Moreno-Ibáñez, M., Gritsevich, M., and Trigo- results (σ = 0.75 Km), there is still a small deviation at Rodríguez, J.M., Icarus, Vol. 250, pp. 544-552, 2015. low heights. This region usually indicates low β values [6] Gritsevich, M.I., Lukashenko, V.T., and Turchak, L.I. and could be linked to the simplifications assumed in the Math. Models Comput. Simul. Vol.8 (1), pp. 1-6, 2016. Numerical Prediction of Meteoric Infrasound Signatures

M. Nemec (1), M. J. Aftosmis (2), P. G. Brown (3) (1) Science & Technology Corp., USA ([email protected]), (2) NASA Ames Research Center, USA, (3) University of Western Ontario, Canada

Abstract the computed signatures, and include a discussion of arrival times and sensitivity to various uncertainties, Infrasound measurements of meteoroids entering the such as the meteor shape and atmospheric conditions. Earth’s atmosphere provide independent estimates of luminous efficiency. When combined with optical ob- log(Pressure) servations, these estimates help refine our assessment > 10 kPa of energy deposition. Moreover, analysis of the infra- < 100 Pa sound signature may give insight into the shock system Near-body meshes Ground Pressure Signatures and fragmentation characteristics, particularly equiva- 0.2 lent blast radius, during the meteor’s descent[1]. ELFO2 Infrasound ELFO4 Sensors This paper presents a direct computational approach 0.1 Simulation for predicting infrasound signatures of small meteors. Our focus is on regional events, where the propagation 0 distance through the atmosphere is less then 150 km. Source Height

Overpressure (Pa) -0.1 52 km We apply techniques from sonic-boom analysis of su- Mach 43 personic aircraft[2] to the propagation of blast waves 7cm Meteor -20 0 20 40 60 80 100 Time (ms) of hypersonic meteors. The physical domain is di- North West Infrasound vided into a nearfield and a farfield region. In the 1 East Sensors Center nearfield, we assume steady inviscid flow in thermo- Simulation chemical equilibrium and use a second-order finite- 0 volume discretization to compute a near-body pressure signature. In the farfield region, the near-body signa- Source Height Overpressure (Pa) -1 ture is propagated through a stratified atmosphere to Mach 10 43 km 0 50 100 150 200 the ground using an augmented Burgers equation. Stardust Time (ms) A novel contribution of this work is a thorough val- idation of the computational predictions. We start by Figure 1: Measured (symbols) and computed (blue analyzing the entry of the Stardust capsule[3], which is lines) infrasound signatures of a meteor-like shape a convenient “artificial” meteor with a well defined ge- (top) and the Stardust capsule (bottom) ometry, trajectory and infrasound record. The results are used to understand the numerical attenuation of the References signature and to account for instrument response. We then consider several cases from the Southern Ontario [1] Silber, E. A., Brown, P. G., Optical observations Meteor Network dataset[1]. of meteors generating infrasound – I: Acoustic Figure 1 shows preliminary results. The first exam- signal identification and phenomenology, J. At- ple (top) involves a 7 cm meteor entering the atmo- mos. Sol.-Terr. Phys. 119, pp 116-128, 2014. sphere at 16 km/s. The left frame shows a model of [2] Aftosmis, M. J., and Nemec, M., Cart3D Simu- the body, while the right frame shows a comparison of lations for the First AIAA Sonic Boom Predic- the predicted infrasound signature with the measured tion Workshop, AIAA Paper 2014–0558, 2014. data. The second example (bottom) shows the Stardust [3] ReVelle, D. O., and Edwards, W. N., Stardust – entry. The simulations closely agree with the observa- An Artificial, low-velocity “meteor” fall and re- tions in both amplitude and wavelength. The final pa- covery: 15 January 2006, Meteorit. Planet. Sci. per will provide a detailed analysis of the accuracy of 42, Nr 3, pp 271-299, 2007. Radio Afterglows from Fireballs

K.S. Obenberger

Space Vehicles Directorate, Air Force Research Laboratory, Kirtland AFB, New Mexico, USA

February 18, 2016

Abstract We present the discovery of meteor trail radio afterglows with the First Station of the Long Wavelength Array (LWA1), a 10 to 88 MHz radio telescope located in central New Mexico. Using the all-sky imag- ing capabilities of the LWA1 we have detected over 100 transient events below 60 MHz. The majority of these events are thought to be emitted afterglows from the plasma trails left by large meteors, a phenomenon distinct from well understood meteor trail reflections. The afterglows are observed to have a smooth and continuous spectra between 20 and 50 MHz, but the spectra is thought to extend well beyond the obser- vational limits of the LWA1. The spectra fit a frequency dependent power law, getting brighter at lower frequencies. My talk will focus on the discovery of the emission, the characterization of the spectra, and a hypothesis of emitted Langmuir waves. I will also discuss ongoing research on the optical counterparts and planned mulitistation radio observations. 1 Heading on level 1 (section)

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4 Exploring uncertainties in fireball modelling using estimators

E. K. Sansom (1), P. A. Bland (1), M. G. Rutten (2), J. Paxman (1), M. Towner (1) (1) Curtin University, Western Australia, (2) DST Group, South Australia. ([email protected]).

Introduction update where the observations (including observation noise nk ∼ N (0, Rk)) are compared to the model Camera networks dedicated to observing fireball phe- prediction. nomena allow the bright flight trajectory of mete- The non-linear system (1) requires non-linear esti- oroids to be triangulated. The evolution of a meteoroid mations algorithms. An EKF predicts the future state throughout its flight can be modelled by a set of simple covariance, Pk+1, by using an approximate, linearised dynamic equations (after [1]): form of (1) for the state transition matrix [2]. An UKF uses a set of sample points to represent the mean dm 1 = − κσρ v3m2/3 state and covariance of a Gaussian distribution. These dt 2 a (1) are individually propagated through (1) and the mean dv 1 κρ v2 = − a + g sin γ state and covariance recalculated. Although fragmen- dt 2 m1/3 e tation is not explicitly included in the model, sudden increases in mass loss are incorporated by the process where ρa, g and γe are the local atmospheric density, gravity and flight angle from horizontal respectively, noise covariance, Qk, to a certain degree. By running cdA0 two simultaneous UKFs in an IMM, with different val- the shape density coefficient κ = 2/3 (cd being the ρm ues for mass in Q , fragmentation events can be iden- A k drag coefficient and 0 the shape parameter) and the tified. All Kalman Filters require initial values for state ch ablation coefficient σ = ∗ (ch is the coefficient of H cd parameters, κ and σ. This requires a preceding optimi- H∗ heat and the enthalpy of vaporisation). sation step using the least squares method (eg. [2]). In order to gain an understanding of the unknown A statistical analysis that includes determination of variables, typical methods perform a least squares likely starting parameters can be performed using the analysis and residuals are used as an indicator of over- iterative Monte Carlo approach of a SISPF. A set of all model errors (eg. [1]). A more robust understand- particles are initiated with a range of values for mass ing of errors introduced by the model itself (1) as well and velocity as well as for κ and σ (which are included as errors in observations can be examined by using as state parameters in xk). Each particle is propagated tracking algorithms. The estimators to be discussed using (1) and its likelihood calculated based on obser- include the Extended Kalman Filter (EKF) as origi- vation values. A new set of particles are resampled nally proposed by Sansom et al. [2]; the Unscented from this pool resulting in a robust final estimate. Kalman filter (UKF) and its inclusion in an Interac- tive Multiple Model estimator (IMM); and Sequential Importance Sampling Particle Filter (SISPF). Conclusion

This presentation will outline the contrasting results of Tracking Algorithms these different tracking methodologies using the flight trajectory of the Bunburra Rockhole meteoroid and as- The state of a meteoroid at any discrete time step, sess the advantages and disadvantages of each. k, may be represented by a state vector xk = [position (l), velocity (v), mass (m)] and an associ- ated covariance matrix, Pk. Although brightness has References not been incorporated at this stage, it can simply be [1] Ceplecha, Z. and ReVelle, D. O., MAPS, Vol. 40, included as an additional state parameter. pp. 35-54, 2005. Tracking algorithms typically perform a prediction [2] Sansom, E. K., Bland, P. A., Paxman, J., Towner, at time k using the system equations and includes a M., MAPS, Vol 50, pp. 1423-1435, 2015. process noise wk ∼ N (0, Qk). This is followed by an First observations with the FRIPON network

F. Colas (1), B. Zanda (1,2), S. Bouley (1,3), J. Vaubaillon (1), C. Marmo (3), Y. Audureau (3), M. K. Kwon (1), P. Vernazza (4), J. Gattacceca (5), S. caminade (3), M. Birlan (1), L. Maquet (1), A. Egal (1), M. rotaru (7), L. Jorda (4), C. Birnbaum (7), C. Blanpain (5), A. Malgoyre (5), J. Lecubin (4), A. Cellino (8), D. Gardiol (8), M; Di Martino (8), C. Nitschelm (9), J. camargo (10), M. Valenzuela (11), L. Ferrière (12), M. Popescu, D. Loizeau

(1) IMCCE, Observatoire de Paris, Paris France ([email protected]), (2) DIMPMC, Muséum National d'Histoire Naturelle, Paris, France, (3) GEOPS, Université Paris Sud, Orsay, France, (4) LAM, Institut Pytheas, Marseille, France, (5) CEREGE, Institut Pytheas, Marseille, France, (6) FRIPON, Collaborative Team, Paris, France, (7) Universciences, Paris, France, (8) INAF – Osservatorio Astrofisico di Torino, 10025 Pino Torinese, Italy, (9) Unidad de Astronomía, Universidad de Antofagasta, Antofagasta, Chile, (10) Observatorio Nacional, Rio de janeiro, Brasil, (11) Universidad de Chile, Santiago, Chile, (12) Natural History Museum, Vienna, Austria, (13) Astronomical Institute of the Romanian Academy, Bucharest, Romania, (14) Laboratoire de Géologie de Lyon, France

Introduction Installation and evolution

FRIPON (Fireball Recovery and InterPlanetary At that time (april 2016) we have installed 50 cameras so Observation Network) was recently founded by ANR half of the network. We also start to install some cameras (Agence Nationale de la Recherche). Its aim is to connect in neighboring countries, the idea is to show hos it works meteoritical science with asteroidal and cometary science and to help other teams to write proposal to extend the in order to better understand solar system formation and network. evolution. The main idea is to set up an observation network covering all the French territory to collect a large number of meteorites (one or two per year) with accurate orbits, allowing us to pinpoint possible parent bodies. At present time more than 50 cameras are installed (real time image can be view on www.fripon.org fig 1), we whole network will consist in 100 all sky camera covering France with an average distance of 100km between stations. To maximize the accuracy of orbit determination, we will mix our optical data with radar data from the GRAVES beacon received by 25 stations. As both the setting up of the network and the creation of search teams for meteorites will need manpower beyond our small team of professionals, we are developing a citizen science network called Vigie-Ciel. The public at large will thus be able to simply use our data, participate in search campaigns or even setup their own cameras. Fig 1 : active network (april 2016) Network characteristics First results Our network have several innovative features compared to previous one: As the density of the network is nominal over south est of France we got several multi detections allowing us to test - First it is an open source project, our aim is to share our our pipe line (detection, astrometrical calibration, orbit work to extend the network to other countries. determination).

- We use digital Gige camera allowing short exposure time for day time observations

- All the cameras are connected pour our headquarter in Orsay. This is important as the detection process take into account the other cameras. If we have a simultaneous detection on several cameras we are sure that it is a meteor. Moreover we will get all the data within a few minutes, compute the trajectory within a few hours and at the end decide for a searching campaign. Refinement of Bolide Characteristics from Infrasound measurements

N. Gi (1), P. Brown (2)

(1) Department of Earth Sciences, University of Western Ontario, London, Ontario, Canada ([email protected]) (2) Department of Physics and Astronomy, University of Western Ontario, London, Ontario, Canada

The characteristics of bolides produced by meter-sized References and larger near-Earth objects (NEOs) impacting the Earth offer a window into the structure and strength of small [1] Edwards, W. N., Brown, P.G., and ReVelle, D.O. NEOs. Fragmentation behavior, energy deposition with (2006), JASTP, 68(10), 1136–1160. height and total energy yield when correlated with pre- [2] Ens, T. A., Brown, P. G., Edwards, W. N., and atmospheric orbits may be used to broaden our under- Silber, E. A. (2012), JASTP, 80, 208-229. standing of the physical properties, structure, and charac- [3] NASA JPL Fireball and Bolide Reports, (2016) teristics of small near-Earth asteroids (NEA) both individ- http://neo.jpl.nasa.gov/fireballs/ ually and as a population. With the development of the International Monitoring System (IMS) in the late 1990s as part of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO), infrasound stations have been continuously collecting low frequency sound for more than a decade. Infrasound is ideal for remote sensing of bolides as such low frequency acoustic waves do not suf- fer significant attenuation over long distances, making detection and characterization of bolides at long ranges possible. Previous works [1,2] have particularly focused on empirical determination of bolide kinetic energy. These works have either been based on extrapolation of ground- level explosions or comparison between infrasound and satellite measurements [2]. When applied to bolides, these empirical period and amplitude estimates may sometimes vary by a factor of several from independent estimates such as those provided by US government sensors [3]. A possible reason for these discrepancies may be the role of secondary bolide characteristics such as height, speed and entry angle in modifying infrasound period and amplitude detected at a particular station. As of mid-2013, the NASA Jet Propulsion Laboratory (JPL) fireball data [3] provides the ground-truth secondary characteristics of bolides, which permits examination of the role these fac- tors play in modifying the apparent infrasound energy estimates. This study examines the infrasonic signals produced by bolides and aims to find the correlation between measured infrasound parameters at IMS stations (dominant signal period, amplitude, and total acoustic energy) and bolide secondary characteristics (height of burst, entry angle, and speed) using data from [3] as ground-truth estimates. In particular, this study explores how the bolide burst height affects infrasonic energy estimates to develop better em- pirical algorithms to improve the accuracy of bolide ki- netic energy.

Annama H5 Meteorite Fall: Orbit, Trajectory and Recovery

M. Gritsevich(1, 2, 7), E. Lyytinen(1), T. Kohout(1, 3), J. Moilanen(1), J.M. Trigo- Rodríguez(4), M. Moreno-Ibáñez(2, 4), S. Midtskogen(5), V. Grokhovsky(7), N. Kruglikov(6, 7), A. Ischenko(7), G. Yakovlev(7), J. Haloda(8, 9), P. Halodova(8), V. Lupovka(10), V. Dmitriev(10), J.I. Peltoniemi(2, 3), A. Aikkila(1), A. Taavitsainen(1), J. Lauanne(1), M. Pekkola(1), P. Kokko(1), P. Lahtinen(1,11)

(1)Finnish Fireball Network, Finland (2) Finnish Geospatial Research Institute, Masala, Finland (3) University of Helsinki, Department of Physics, Finland (4) Institute of Space Sciences (CSIC-IEEC), Barcelona, Spain (5) Norwegian Meteor Network, Norway (6) Institute of Metal Physics, Russian Academy of Science, Ekaterinburg, Russia (7) Ural Federal University, Ekaterinburg, Russia (8) Czech Geological Survey, Prague, Czech Republic (9) Oxford Instruments NanoAnalysis, Bucks, UK (10) Moscow State University for Geodesy and Cartography, Moscow, Russia (11) Finnish Meteorological Institute, Helsinki, Finland

[email protected]

We present a summary on the trajectory reconstruction, dark flight simulations and pre- impact orbit for the bright fireball appeared in the night sky over Kola Peninsula, close to Finnish border, on April 19, 2014 at 00h14m13.0±0.1s (according to Finnish time which equals to UTC +2h). The fireball was instrumentally recorded in Finland from Kuusamo, Mikkeli and Muhos observing sites belonging to the Finnish Fireball Network. Additionally, a video made from Snezhnogorsk (Russia) from the opposite side of the fireball track, was carefully calibrated and taken into account in trajectory reconstruction. Based on the thorough analysis of the fireball it was concluded that part of the meteoroid survived the atmospheric entry and reached the ground. To further specify impact area dark flight simulations were done to build a strewn field map showing most probable distribution of fragments. The 5-day expedition with 4 participants from Russia and Finland took place at the end of May following snow melt and preceding vegetation growth. On May 29, 2014, first 120.35 g meteorite fragment was found on a local forest road within the predicted impact area. Second 47.54 g meteorite fragment fully covered with fusion crust was recovered nearby on the following day. Both pieces were preserved in very good condition with zero weathering grade and were thoroughly studied in the laboratory. AUTOMATIC DETECTION OF METEORITES IN NEXRAD RADAR

Mike Hankey1, Marc Fries2, Rob Matson3, Jeffrey Fries4 1. – Genesee NY, USA 2. NASA Astromaterials Research and Exploration Science, Johnson Space Center, Houston, Texas, USA 3. Leidos 4. First Weather Group, Air Force Weather Agency

For several years meteorite recovery in the United States has been greatly enhanced by using doppler weather radar images to determine possible fall zones for meteorites produced by witnessed fireballs. While most events leave no record on the doppler radar, some fireballs do. Based on the successful recovery of over 10 meteorite falls 'under the radar', and the discovery of radar on 10 historic falls, it is believed that meteoritic dust and or actual meteorites falling to the ground can be recorded on doppler weather radar.

Up until this point, the process of detecting the radar signatures has been a manual one and dependent on prior accurate knowledge of the fall time and estimated ground track. This manual detection process is labor intensive and can take several hours per event. Recent technological developments by NOAA now help enable the automation of these tasks. This in combination with advancements by the American Meteor Society in the tracking and plotting of witnessed fireballs has opened the possibility for automatic detection of meteorites in NEXRAD Radar Archives. Here in the processes for fireball triangulation, search area determination, radar interfacing, data extraction, storage, search, detection and plotting are explained. Numerical model of the Chelyabinsk meteoroid as a strengthless object

V. Shuvalov, V. Svetsov, O. Popova, D. Glazachev Institute for Dynamics of Geospheres Russian Academy of Sciences (IDG RAS), Moscow, Russia ([email protected])

The Chelyabinsk airburst of 15 February 2013 was an [2] Borovicka J., Spurny P., Brown P., Wiegert P., extraordinary event due to its large kinetic energy about Kalenda P., Clark D., Shrbeny L. The trajectory, structure 500 kt TNT [1-3]. The 20-m-diameter asteroid deposited and origin of the Chelyabinsk asteroidal impactor, 2013, the most part of its energy in the atmosphere at an Nature 503, 235-237 altitudes about 50-23 km and produced significant damage [3] Brown P. G.et al. A 500-kiloton airburst over Chelya- and injuries over a large populated area. Many papers binsk and an enhanced hazard from small impactors, considering various effects of the Chelyabinsk event have 2013, Nature 503, 238-241 been published but a rich observational material leaves [4] Shuvalov V.V., Svettsov V.V., and Trubetskaya I.A., room for further research. In this study we applied a An estimate for the size of the area of damage on the numerical model, initially developed for simulations of Earth’s surface after impacts of 10300m asteroids, Solar the entry of large (>several tens of meters) meteoroids, to Syst. Res., 2013, vol. 47, no. 4, pp. 260–267. the Chelyabinsk event. [5] Shuvalov V.V., Artemieva N.A., Numerical modeling of Tunguskalike impacts, Planetary and Space Science, In this model, disruption and deceleration of a meteoroid 2002, vol. 50, pp. 181–192. in the atmosphere and following propagation of a shock [6] Shuvalov V.V. and Trubetskaya I.A., Numerical wave to long distances are simulated using a two-step modeling of impact induced aerial bursts, Solar Syst. Res., approach described in [4]. At the first step, the motion of a 2007, vol. 41, no. 3, pp. 220–230. meteoroid in the atmosphere is simulated in the coordinate [7] Shuvalov V.V. Multi-dimensional hydrodynamic code system associated with the moving body, taking into SOVA for interfacial flows: Application to thermal layer account its deformation, deceleration, destruction, and effect, Shock Waves. 1999. Vol. 9. №. 6. P. 381–390 evaporation. The model, equations, and numerical scheme have been described in [5], [6]. The entering body is treated as a strengthless liquid-like object and its deformation and the flow are described by the hydrodynamic equations.

The distributions of velocity, energy and density in the atmosphere are used as initial data for the second step of simulations. At this step, the propagation of an air shock wave to great distances over the Earth’s surface is simulated in a coordinate system associated with the Earth. We calculate pressures behind the shock wave and compare them with other models and shock effects observed after the Chelyabinsk airburst. Both calculation steps are implemented using the SOVA numerical method [7]. Using the distributions of temperature and density obtained in the first and second steps we calculated radiation fluxes on the Earth's surface and compared the results with the observed light curve of the Chelyabinsk meteoroid. Applicability and limitations of the model will be discussed.

The work was partially supported by grant of the Russian Science Foundation 16-17-00107.

References [1] Popova, O. P., Jenniskens, P., Emel'yanenko, V., et al. Chelyabinsk Airburst, Damage Assessment, Meteorite Recovery, and Characterization, 2013, Science, 342, 1069- 1073 ORISON, a stratospheric instrumentation project with potential applications in meteoroid science

Alejandro Sanchez de Miguel, [email protected] ,Universidad Complutense de Madrid, Madrid, Spain Jose Luis Ortiz, [email protected] IAA-CSIC, Granada, Spain Jose Juan Lopez-Moreno, [email protected] IAA-CSIC, Granada, Spain Rene Duffard, [email protected] IAA-CSIC, Granada, Spain Thomas Mueller, [email protected] Max Planck Institute for Extraterrestrial Physics, Garching, Germany Jürgen Wolf, [email protected] Institute of Space Systems, University of Stuttgart, Stuttgart, Germany Karsten Schindler, [email protected] Institute of Space Systems, University of Stuttgart, Stuttgart, Germany Friederike Graf, [email protected] Institute of Space Systems, University of Stuttgart, Stuttgart, Germany

Astronomical research based on satellites is extremely expensive, complex, requires years of development and the overall difficulties are immense. The H2020-funded ORISON project addresses the feasibility study and the design of a global infrastructure based on platforms onboard stratospheric balloons, which allows overcoming the limitations that the Earth’s atmosphere imposes, but at a much lower cost and with fewer complications than in satellite platforms. The overall idea is the use of small low-cost stratospheric balloons, either individually or as a fleet, equipped with stabilized light-weight medium-sized telescopes and other instruments to perform specific tasks in short-duration missions. They can carry different payloads for specific “experiments” too, and should be configurable to some degree to accommodate variable instrumentation. This balloon-based instrumentation should be designed to be launched from many sites on Earth, not necessarily from remote sites such as Antarctica or near the North Pole, and at low cost compared with large balloon programs. Meteor science can be performed using specific low-weight instruments in this stabilized platform provided that there is enough interest in the meteor community, and several science cases will be discussed in this presentation. Some amateur experiments of meteor shower observations with stratospheric balloons will be presented as well. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 690013 The exosphere of Mercury as a detector of Encke meteoroids

A. A. Christou (1), R. M. Killen (2), M. H. Burger (3) (1) Armagh Observatory, Armagh, UK ([email protected]), (2) NASA Goddard Space Flight Center, Greenbelt, MD, USA, (3) Morgan State University, Baltimore, MD, USA

The variation and intensity of meteor activity in the Earth’s atmosphere is well characterised, thanks to the proliferation of survey programmes employing radar, radio & optical techniques. Combined with rig- orous analysis of the data, they constrain the nature and sources of meteoroids. Still, the potential of utilis- ing other planetary bodies to extend our knowledge of the spatial distribution of meteoroids remains largely untapped. The recent close passage of comet C/2013 A1 (Siding Spring) to Mars, which coincided with a sudden increase in the meteoric metal content of its upper atmosphere as detected by orbiting spacecraft [1], highlighted the role of techniques other than those Figure 1: Descending nodes on Mercury’s orbit plane at JD2487500 of 1000 particles ejected from Encke principally used at the Earth as proxies for meteoroid −3 flux variations in the vicinity of planetary bodies. 10k yr ago and with β = 2 × 10 . Red points: parti- cles with v < 10 m s−1; black points: particles with The planet Mercury is enveloped in a tenuous at- ej 10 m s−1 < v < 100 m s−1. The arrow indicates the mosphere, a collisionless cloud of neutrals and ions ej direction of increasing f away from Mercury’s perihe- [2]. Recent observations by the Mercury Atmospheric, lion (+x axis). Most particles with v < 10 m s−1 and Surface Composition Spectrometer (MASCS) on- ej intersect Mercury’s orbit (black ellipse) at f ' 30◦. board the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) space- craft [3] found that the atomic Ca abundance in the ex- kyr ago impact on the nightside hemisphere of Mer- ◦ ◦ osphere varies as a function of Mercury’s true anomaly cury at 350 < f < 30 [5] (Fig. 1). f. Subsequent modelling [4] showed that these varia- In this presentation, we will describe our model re- tions may be attributed to impact vaporization of sur- sults and discuss the implications of our findings for face material by meteoroid infall. However, an addi- the Encke stream of meteoroids. Linkages between tional dust source was required to explain a Ca excess the Mercury-intercepting part of the stream and docu- at f = 25◦±5◦. Killen & Hahn suggested that parti- mented Taurid activity at the Earth will be attempted. cles from comet 2P/Encke, crossing just outside Mer- ◦ cury’s orbit at f = 45 , may be the culprit. References By simulating numerically the stream of meteoroids ejected from Encke up to 50kyr ago we sought to iden- [1] Tricarico, P., Geophys. Res. Lett., Vol. 42, tify those particles that impact Mercury at the present pp.4752-4754, 2015. epoch and test the Killen & Hahn conjecture. [2] Killen, R. M., Space Sci. Rev., Vol. 132, pp. 433- We find that Encke particles evolving solely under 509, 2007. [3] Burger, M. H., et al, Icarus, Vol. 238, pp. 51-58, the gravity of the planets and the Sun encounter Mer- 2014. cury at f = 50 − 60◦, well after the Ca excess emis- [4] Killen, R. M., and Hahn, J. M., Icarus, Vol. 250, sion. This result is independent of the time of ejection. pp. 230-237, 2015. However, adding Poynting-Robertson (P-R) drag in [5] Christou, A. A., Killen, R. M., and Burger, our model causes smaller, older particles to encounter M. H., Geophys. Res. Lett., Vol. 42, pp.7311- Mercury progressively earlier in the Hermean year. In 7318, 2015. particular, mm-sized grains ejected between 10 and 20 Determination of meteoroid entry parameters for terrestrial strewn fields

M. Bronikowska (1), N. A. Artemieva (2,3), K. Wünnemann (4), W. Szczucinski´ (1) (1) Institute of Geology, Adam Mickiewicz University, Makow Polnych 16, 61-606 Poznan, Poland (2) Institute of Dynamics of Geospheres, Russian Academy of Sciences (3) Planetary Science Institute, Tuscon (4) Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Berlin

Introduction

Crater strewn fields resulting from fragmentation of cosmic bodies in the atmosphere are common on plan- ets with atmosphere [1], [2], [3]. Several terrestrial crater fields were formed by iron projectiles. Existing physical models of meteoroid interaction with the at- mosphere [1] enable to determine entry parameters of such crater-forming bodies.

Methods

In this study we combine an atmospheric entry model with the simulation of impact crater formation. The aim is to determine entry parameters for several known terrestrial strewn fields. First, we use standard equa- tions describing ablation and deceleration of impact- Figure 1: The observed Morasko strewn field (top) and ing bodies in in the atmosphere [4]. To simulate the an example of the modeled crater distribution (bot- fragmentation process, we use the modified so-called tom). The meteoroid’s trajectory is marked by the Pancake approximation [4]. To determine the position black arrow. Some meteorites tens of kilograms are of each big fragment we use a Monte Carlo method shown by stars. and the standard cumulative size-frequency distribu- tion of fragments. These fragments move indepen- acknowledgements dently to the ground and some of them may be sub- jected to another fragmentation cycle. To estimate The work was supported by National Science Center crater diameters, we use standard scaling laws [5]. To (Poland), grant no. 2013/09/B/ST10/01666. account for the effect of material properties on crater size we consider material-dependent parameters de- rived from simulations with the multi-material multi- References rheology iSALE2D hydrocode [6]. [1] Passey and Melosh (1980) Icarus, 42, 2011. [2] Artemieva N. and Shuvalov V. (2011) JGR, 106, 3297. Results [3] Herrick R. R. and Phillips R. J. (1994) Icarus 112, 253. To exclude non-suitable pre-entry parameters for ter- [4] Chyba C. F. et al. (1993) Nature, 361, 40. restrial strewn fields, we use criteria based on: 1) the [5] Holsapple and Housen (2007), Icarus 187, 345. total number of craters, 2) the diameter of the biggest [6] Wünnemann K. et al. (2006) Icarus 180, 514. crater, 3) the maximum distance between two craters. Meteoroid Impact Detection for Exploration of Asteroids (MIDEA): A concept for asteroid prospecting

N. Lee, S. Close Stanford University, Stanford, CA, USA ([email protected])

Meteoroids are dispersed throughout the solar sys- tem and provide a constant source of impacts on larger 0.7 Total flux bodies, resulting in erosion of the material on their 0.6 >20 km/s surfaces. The Meteoroid Impact Detection for Ex- -2 -1 Periapsis ploration of Asteroids (MIDEA) concept, shown in 0.5 Apoapsis Figure 1, leverages this natural phenomenon to deter- 0.4 mine the composition of asteroid surfaces through dis- tributed plasma sensors on nanosatellites. 0.3 The material excavated from an asteroid surface by 0.2 a meteoroid impact includes solid and molten ejecta, but some of this material is vaporized and ionized, 0.1

forming a plasma that expands into the environment Sun-facing impacts > ng [m day ] 0 around the asteroid. The plasma can be detected by a 2016-07 2017-01 2017-07 2018-01 low-power electrostatic probe at a range of up to sev- Figure 2: Impact rate of nanogram and larger mete- eral hundred meters, characterized through time-of- oroids from the sun direction over Itokawa’s orbit. flight mass spectrometry, and traced back to the point of impact to construct a composition map of the aster- oid surface. oids ranging from 100 to 1000 m in size, and was chosen as a representative case. Figure 2 shows the This paper focuses on the characterization of im- impact rate of nanogram and larger meteoroids from pact rate on asteroids using models of meteoroid flux. the sun direction over Itokawa’s orbit. Impact plasma Itokawa is one of over 7000 known near-Earth aster- formed on the sun-facing size will expand from a pos- itively biased surface due to photoemission, allowing electrons to be re-absorbed into the surface and leav- Plasma measurement Parent spacecraft ing the positive ions free to reach the orbiting sensors. The impact rate was computed using NASA’s Mete- oroid Engineering Model with Itokawa’s orbital posi- tion and velocity from JPL’s HORIZONS system, and Impact plasma extrapolated from microgram to nanogram meteoroids using the Grün interplanetary flux model. An impact velocity threshold of 20 km/s was applied to consider Surface map only those impacts fast enough to produce a discern- able charge from an overhead spacecraft. The impact rate was found to vary from 0.037 to 0.27 m−2 · day−1 with the maximum coinciding with Meteoroids Distributed sensors the time period prior to periapsis, when Itokawa’s sun- ward velocity component is greatest. These rates cor- Figure 1: Overview of the MIDEA system concept. respond to approximately 3–25 impacts per minute A parent spacecraft synthesizes impact plasma mea- over the total sun-facing area of the asteroid, allowing surements collected by distributed sensors on smaller for rapid characterization of the surface composition. spacecraft to construct a map of potential resources on This material is based upon work supported by the asteroid surface. NASA under award No. NNX15AD70G Measuring the temperature of impact plumes from the analysis of lunar impact flashes

J.M. Madiedo (1,2), J.L. Ortiz (3), (1) Departamento de Física Atómica, Molecular y Nuclear, Universidad de Sevilla, Spain, (2) Facultad de Ciencias Experimentales, Universidad de Huelva, Spain, (3) Instituto de Astrofísica de Andalucía , CSIC, Apt. 3004, 18080 Granada, Spain, ([email protected])

Introduction

Different researchers have studied the impacts of meteoroids on the lunar surface by analyzing the flashes produced during these collisions (see e.g. [1] to [4]). In this way different parameters can be determined, such as the energy of the impactor, its mass, and the size of the resulting crater. From the frequency of these events, paramount information related to the impact hazard for Earth can be also derived [1, 5]. However, the detection of these impact flashes has so far been performed in the visible range. Our team started in 2009 a lunar impact flashes monitoring program named MIDAS [5], which is the continuation of the lunar impact flashes monitoring project started by the second author in 1999 [6]. Recently, in addition to the observations performed in visible band, we have also conducted a monitoring of the night side of the Moon in the near-infrared (nIR) by using a specific nIR filter. In this way, we can analyze the behaviour of these impact flashes in different spectral bands. The analysis of these events is providing the value of the emission efficiency for impact flashes in the nIR. Besides, the temperature of the impact plume, and the evolution with time of this temperature, can be obtained. Our results suggest that condensation gives rise to an equilibrium in the impact plume, and that the energy radiated as a consequence of the release of the evaporation energy leads to a prolongation of radiative response.

References [1] Ortiz J. L. et al., 2006, Icarus, 184, 319. [2] Madiedo J. M., Ortiz J. L., Morales N., Cabrera-Caño J., 2014, MNRAS, 439, 2364. [3] Suggs R. M., Moser D. E., Cooke W., Suggs R. J., 2014, Icarus, 238, 23. [4] Ortiz J. L., Sada P. V., Bellot Rubio L. R., Aceituno F. V., Aceituno J., Gutierrez P. J., Thiele U., 2000, Nature, 405, 921. [5] Madiedo J.M., Ortiz J.L., Morales N., Cabrera-Caño, J., MNRAS, Vol. 439, pp. 2364-2369, 2014. [6] Ortiz J. L., Aceituno F. J., Aceituno J., 1999. A&A, 343, L57. Impact hazards of meter size meteorites

N. Nogami International Meteor Organization, Japan

Introduction References [1] „On state-of-the-art of the system preparation for large So far impact hazards of NEO (Near Earth Object) have scale damage happening at the third and fourth nuclear frequently been discussed because of those serious and reactors in Takahama nuclear power plant” -A material for fatal stories to modern civil life. On the other hand, suppkementary explanation- March. 2014, Kansai however, as one factor of natural disaster for considering Electric company. In Japanese countermeasures an impact phenomenon has been [2] “Lee’s loss prevention in the process industries neglected because it may happen too rare, once per ten hazards identification, assessment and control” Third ed., thousands or a few million years, and too hard to prevent Butterworth-Heinemann. 2005. it by the latest technology. [1] These NEO are size of several ten meters at smallest. But smaller size meteorites have more frequent chance to impact to the Earth and may give some unexpected heavy damage to disregard. This presentation treats meter size meteorites impact frequency, damage and some hints of countermeasures for them.

Impact frequency and damage level of meter size meteorites

Frequency of focused meteor size in this presentation is from thousands to several years. Some case histories including impact damages by the meteorites will be mentioned. Especially as frequency level of less than one hundred years are close to lifetime of an industrial factory or civil community, one will understand to take into account this kind of impact as a reality. On talking about a frequency, some people may focus on “probability of some region like a county, area or a continent”. This presentation mentioned briefly a couple of past impacts and impact probability in Japan where is quite limited small area in the world. In addition, damage records from these case histories will be good reference to considering and imaging damage effect for them. Here the word “damage” contains primary one and secondary one. The former means a crater, shock wave, mechanical damage, heat damage and so on. The later includes trajectories from the crater, missiles of debris broken by shock wave, leakage of harmful materials by the impact and so on.

Countermeasures for an impact

By applying the knowledge of loss prevention in the safety engineering, some key points of countermeasure for impact of titled size meteorites are proposed. [2] Even if some these knowledge treat lower energy level of trajectories, shock wave and so on, treatment from engineering stand point will be useful and worthwhile. Some idea may be utilized for loss prevention in industrial works and plants, and architectures.

Fig 1 Meteoroids 2016 Experimental simulation of the atmospheric ablation of cosmic dust particles

John Plane (1), Juan Carlos Gomez Martin (1), David Bones (1), Juan Diego Carrillo Sanchez (1), Alexander James (1) and Diego Janches

(1) University of Leeds, School of Chemistry, Leeds, United Kingdom ([email protected]), (2) Space Weather Lab, GSFC NASA, Greenbelt, USA

The ablation of meteoroids entering a planetary atmosphere is the critical process which produces layers of metal atoms and ions, as well as the meteoric smoke particles which act as condensation nuclei for middle atmospheric clouds. Ablation has been modelled in the past by coupling the classical equations of meteor physics to a thermodynamic model of a high temperature silicate melt, and assuming Langmuir evaporation of the constituent elements into a vacuum. A current example of such a model is the Chemical Ablation Model (CABMOD), developed at the University of Leeds [Vondrak et al., 2008]. Although CABMOD successfully predicts the differential ablation which is inferred from the relative abundances of the layers of Na, Fe and Ca atoms in the terrestrial mesosphere [Carrillo- Sanchez et al., 2015], and the time-resolved variation of radar head echoes [Janches et al., 2009], the underlying assumptions of this type of model have never been tested. We have therefore recently constructed at Leeds the Meteoric Ablation Simulator (MASI). In this apparatus, meteoritic analogues of cosmic dust are flash heated to over 2800 K in a few seconds, inside a vacuum chamber. A fast time response pyrometer coupled to a temperature controller is used to match the particle heating profile to that which a meteoroid of specified mass, entry angle and velocity would experience. The evaporation of metals is measured in real time by time-resolved laser induced fluorescence spectroscopy using a very high repetition rate YAG laser pumping two dye lasers, so that the ablation of a pair of metals can be studied simultaneously. Results have been obtained for a variety of particle sizes (20 – 150 µm), types (carbonaceous and chondritic), and entry velocities (14 – 40 km s-1). Although CABMOD correctly predicts the order of evaporation of Na, Fe and Ca, there are significant differences with the observed ablation onset temperature and duration over which each element ablates. This has important consequences for the height ranges over which elements ablate, as well as the rates of ablation which determine the production of electrons and hence the detectability of a meteoroid by radar. In this presentation, the implications of the experimental results for the interpretation of radar observations, mass flux estimates and the modelling of metal layers will be discussed.

Carrillo-Sanchez, J. D., J. M. C. Plane, W. Feng, D. Nesvorny, and D. Janches (2015), On the size and velocity distribution of cosmic dust particles entering the atmosphere, Geophysical Research Letters, 42(15), 6518-6525, doi:10.1002/2015gl065149.

Janches, D., L. P. Dyrud, S. L. Broadley, and J. M. C. Plane (2009), First observation of micrometeoroid differential ablation in the atmosphere, Geophys. Res. Lett., 36, L06101.

Vondrak, T., J. M. C. Plane, S. Broadley, and D. Janches (2008), A chemical model of meteoric ablation, Atmos. Chem. Phys., 8(23), 7015-7031. A Comparison of Radiometric Calibration Techniques for Lunar Impact Flashes

R. Suggs NASA Marshall Space Flight Center, Huntsville, Alabama ([email protected])

Introduction References

Video observations of lunar impact flashes have been [1] Bellot Rubio, L.R., Ortiz, J.L., Sada, P.V., 2000. made by a number of researchers since the late 1990’s and Observation and interpretation of meteoroid impact the problem of determination of the impact energies has flashes on the Moon. Earth Moon Planets 82 (83), 575- been approached in different ways (Bellot Rubio, et al., 598. 2000 [1], Bouley, et al., 2012.[2], Suggs, et al. 2014 [3], [2] Bouley, S., Baratoux, D., Vaubaillon, J., Mocquet, A., Rembold and Ryan 2015 [4], Ortiz, et al. 2015 [5]) . The Le Feuvre, M., Colas, F., Benhaldoun, Z., Daassou, A., wide spectral response of the unfiltered video cameras in Sabil, M., Lognonne, P., 2012. Power and durateion of use for all published measurements necessitates color impact flashes on the Moon: Implication for the cause of correction for the standard filter magnitudes available for radiation. Icarus 218, 115-124. the comparison stars. An estimate of the color of the [3] Suggs, R.M., Moser, D.E., Cooke, W.J., Suggs, R.J., impact flash is also needed to correct it to the chosen 2014. The flux of kilogram-sized meteoroids from lunar passband. Magnitudes corrected to standard filters are impact monitoring. Icarus 238, 21-36. then used to determine the luminous energy in the filter [4] Rembold, J.J., Ryan, E.V., 2015. Charactrization and passband according to the stellar atmosphere calibrations Analysis of Near-Earth Objects via Lunar Impact of Bessell et al., 1998 [6]. Figure 1 illustrates the Observations. Planetary and Space Science 117, 119-126. problem. The camera pass band is the wide black curve [5] Ortiz, J.L., Madiedo, J.M., Morales, N., Santos-Sanz, and the blue, green, red, and magenta curves show the P., Aceituno, F.J.. 2015. Lunar impact flashes from band passes of the Johnson-Cousins B, V, R, and I filters Geminids: analysis of luminous efficiencies and the flux for which we have calibration star magnitudes. The of large meteoroids on Earth. Monthly Notices of the blackbody curve of an impact flash of temperature 2800K Royal Astronomical Society 454, 344-352. (Nemtchinov, et al., 1998 [7]) is the dashed line. This [6] Bessell, M.S., Castelli, F., Plez, B., 1998. Model paper compares the various photometric calibration atmospheres broad-band colors, bolometric corrections techniques and how they address the color corrections and temperature calibrations for O-M stars. Astronomy necessary for the calculation of luminous energy and Astrophysics 333, 231-250. 1998. (radiometry) of impact flashes. This issue has significant [7] Nemtchinov, I.V., Shuvalov, V.V., Artemieva, N.A, implications for determination of luminous efficiency, Ivanov, B.A., Kosarev, I.B., Trubetskaya, I.A., 1998. Light predictions of impact crater sizes for observed flashes, and impulse created by meteoroids impacting the Moon. the flux of meteoroids in the 10s of grams to kilogram size Lunar and Planetary Science, XXIX. Abstract 1032. range.

Fig 1 Camera and filter responses with 2800K flash blackbody Abstract High resolution orbits with high speed shutters

Felix Bettonvil

This contribution will describe a novel photographic instrument, based on Liquid Crystal shutter technology, which enables the chopping of meteor trails at a rate of 200-400 cycl/sec. Together with a long-focal lens it enables measurement of the apparent velocity and deceleration with high accuracy, resulting in an increase of the sample of precise orbits. The instrument has been in use at several major shower maxima and the obtained results will be presented. An outlook is given for further increase of the performance.

Current status of Polish Fireball Network

M. Wi śniewski (1,2), P. Żoł ądek (1), A. Olech (1,3), Z. Tyminski (1,4), M. Maciejewski (1), K. Fietkiewicz (1), M. Gozdalski (1), M. P. Gawro ński (1,5), T. Suchodolski (1,6), M. Myszkiewicz (1), M. Stolarz(1), K. Polakowski (1) (1) Polish Fireball Network, Comets and Meteors Workshop, ul. Bartycka 18, 00-716 Warsaw, Poland (2) Central Office of Measures, ul. Elektoralna 2, 00-139 Warsaw, Poland (3) Nicolaus Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warsaw, Poland (4) National Centre of Nuclear Research RC POLATOM, Soltan 7, Otwock-Świerk, Poland (5) Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus Univ., Grudzi ądzka 5, 87-100 Toru ń, Poland (6) Space Research Centre, Polish Academy of Sciences, ul. Bartycka 18A, 00-716 Warszawa, Poland ([email protected])

Introduction

Since 2004 the Polish sky has been patrolled by cameras of Polish Fireball Network (PFN). Most of PFN observers are amateurs, members of Comets and Meteors Workshop and perform observations from their homes. Some stations are located in astronomical clubs and schools [1].

Cameras of PFN

The network consists of 33 continuously working stations with 62 cameras. In Most stations we use sensitive CCTV analog video cameras equipped with lenses with 65.6×49.2° field of view. The Typical resolution is 5'/pixel. Limiting magnitude of the system is +2 magnitude for meteors [1]. We use MetRec [2] and UFOCapture[3] software for meteor detection. RecoStar and UFOAnnalyzer software are used for astrometric reduction of video recordings. Fig 1 Calculated trajectories of meteoroids in 2011-2015

New "Meteor Digital Cameras" (MDC) are based on Results of PFN in years 2011-2015 sensitive DMK 23GX236. This camera have resolution of 1920x1200 pixels. The new cameras are working with In years 2011-2015 PFN cameras recorded 215049 single lenses with focal length of 2.4 mm which gives 130x80 events. Using this data 34608 trajectories and orbits was deg field of view and resolution of 4'/pixel. We working calculated and visualized on Fig. 1. Detailed numbers of on setup with digital camera for observation of the meteor meteors was presented in Table 1. spectra. For the tests were using Pointgrey and QHY cameras. This work was supported by the National Science Center

(decision No. DEC-2013/09/B/ST9/02168) Detections from all PFN cameras are automatically transmitted via internet to central server where double station events are detected, analysed and then trajectory References and obit is determined. All calculations are checked by [1] A. Olech, P. Zoladek, M. Wisniewski, Krasnowski M., manual inspection. We create the PyFN software for M. Kwinta, T. Fajfer, K. Fietkiewicz, D. Dorosz, L. trajectory and orbit calculation. PyFN utilize the Celpeha Kowalski, J. Olejnik, K. Mularczyk, and K. Zloczewski. method described in [4]. Polish Fireball Network. In L. Bastiaens, J. Verbert, and J.-M. V. C. Wislez, editors, Proceedings of the Table 1 Results of PFN in last 5 years. International Meteor Conference, Oostmalle, Belgium, pages 53–62, August 2006. Year Detections Orbits [2] S. Molau. The meteor detection software MetRec. In 2011 24099 3430 W. J. Baggaley and V. Porubcan, editors, Meteroids 1998, 2012 28471 4186 pages 131–+, 1999. [3] SonotaCo (2005). “UFCaptureV2 Users Manual”. 2013 36347 6114 http://sonotaco.com/soft/UFO2/help/english/index.html . 2014 46936 7351 [4] Z. Ceplecha. Geometric, dynamic, orbital and photometric data on meteoroids from photographic 2015 79083 13528 fireball networks. Bulletin of the Astronomical Institutes of Czechoslovakia, 38:222–234, July 1987.