175 research outputs found
Groundbased investigation of asteroid 9969 Braille, target of the spacecraft mission Deep Space 1
No full textAsteroid 9969 Braille (1992 KD) was encountered on July 29, 1999 by the Deep Space 1 mission, the first of NASA's New Millennium Program, launched on October 24 1998. The data obtained by the space mission seem to indicate a composition of the object similar to that of Vesta. To complete the information obtained in the infrared region by the Deep Space 1 mission we have performed a visible spectroscopic and photometric investigation of the asteroid respectively with the 1.5 m telescope and the NTT of ESO, La Silla. The spectrum was obtained in the spectral range 4500-8200 Å and, for the photometry, BVRI filters were used. In this paper we report the results of the analysis of the data obtained indicating that, on the basis of our visible data, the composition of the asteroid may range from V-type to Q-type, but we observe also a strong similarity to the H-type ordinary chondrites. Based on observations carried out at the European Southern Observatory (ESO) of La Silla, Chile, programs N.62S-0173 and N.62S-0305A
Modelling asteroid surfaces from observations and irradiation experiments: the case of 832 Karin
No full textWe define a new approach to model asteroidal space weathering. We started from recent results of ion irradiation experiments (60–400 keV) of meteorites and silicates to give an accurate description of space weathering, and we included its effects in the Shkuratov model. We found that the reddening and darkening process (in the range 0.3–2.5 μm) does not significantly affect the position or relative intensities of the mafic silicate absorption features and it mainly affects the continuum of reflectance spectra. This continuum is parameterized by a CS coefficient, which is strongly related with the number of displacements per unit area (damage parameter); we consequently obtained an exposure time curve, and corresponding astrophysical timescales. We applied this new description of space weathering to model observed spectra of Asteroid 832 Karin, in the 0.4–2.4 μm spectral region. The obtained exposure time is slightly lower than the age of the impact and collisional breakup which originated the Karin asteroidal family, i.e., about 5.75×106 years
Analysis of the meteorite-producing fireballs registered by the MOROI component of the FRIPON network
No full textInternational audience1. IntroductionThe Fireball Recovery and Inter Planetary Observation Network (FRIPON) network [1] uses all-sky cameras in order to detect fireballs. The FRIPON network comprises over 150 cameras installed all over Europe [1]. In this work we focus on the results obtained by the Meteorite Orbits Reconstruction by Optical Imaging (MOROI) [2] component of the FRIPON network in Romania. As of May 2022, the MOROI network detects the events with the use of 13 all-sky cameras.2. MethodsThe method for computing the fireball trajectory used by FRIPON is presented in [3].The height, velocity and slope γ of the meteoroid are the input data for computing the ballistic coefficient α and the mass-loss parameter β. We select the candidates that are likely to produce meteorites of the ground using the α-β algorithm presented in [4], [5], [6], [7].3. ResultsStarting from January 2021 (the starting moment of data fusion of the MOROI network into the FRIPON network) until the present time (May 2022) over 100 meteors were detected. We present the most spectacular events that are likely to result on a meteorite production on the surface of the Earth. Figure 1: The outcome of the FRIPON (MOROI) detections in RomaniaIn Figure 1 are represented the coordinates of the meteoroids with noticeable deceleration in the (ln(αsinγ),lnβ) coordinates system. The values of the shape parameter correspond to the cases when the meteoroid doesn't rotate (µ=0) or rotates uniformly (µ=2/3). The boundaries ('likely fall', 'possible fall', 'unlikely fall') are represented for meteoroids with final mass of 50 g.We processed the 100 detections of the FRIPON (MOROI) network in Romania. From this amount of data, we found 15 fireball events with noticeable deceleration. We found one event in the 'likely fall' area and three events in the 'possible fall' area. The fireball that is likely to produce meteorites was detected by the MOROI network on 24.11.2021 at 19:20:57 UT.We model the dark flight trajectory of the meteoroids with the 'likely fall' and 'possible fall' outcomes and determine their strewn field with the model presented in [8], [9]. We use the wind model from the European Centre for Medium-Range Weather Forecasts (ECMWF).A meteorite recovery campaign will be organised to identify the strewn field area.Acknowledgement.The work of IB and MB was partially supported by a grant of the Romanian Ministry of Education and Research, CNCS-UEFISCDI, project number PN-III-P1-1.1-PD-2019-0784, within PNCDI III. The work of IB, MB, AN was partially supported by a grant of the Ministry of National Education and Scientific Research, PNIII-P2-1214/25.10.2021, program no. 36SOL/2021. JM and MG acknowledge the Academy of Finland project no. 325806 (PlanetS).References:[1] Colas F., Zanda B., Bouley S., Jeanne S., Malgoyre A., Birlan M., Blanpain C., Gattacceca J., Jorda L., Lecubin J., et al. (385 more) FRIPON: a worldwide network to track incoming meteoroids. Astronomy &. Astrophys. 644, A53. doi:10.1051/0004-6361/202038649. 2020.[2] Nedelcu D.A., Birlan M., Turcu V., Boaca I., Badescu O., Gornea A., Sonka A.B., Blagoi O., Danescu C., Paraschiv P. Meteorites Orbits Reconstruction by Optical Imaging (MOROI) Network. Romanian Astronomical Journal 28(1), 57 - 65. 2018.[3] Jeanne, S., Colas, F., Zanda, B., Birlan, M., Vaubaillon, J., Bouley, S., Vernazza, P., Jorda, L., Gattacceca, J., Rault, J. L., Carbognani, A., Gardiol, D., Lamy, H., Baratoux, D., Blanpain, C., Malgoyre, A., Lecubin, J., Marmo, C., Hewins, P. Calibration of fish-eye lens and error estimation on fireball trajectories: application to the FRIPON network. Astronomy and Astrophysics, 627:A78. 2019.[4] Gritsevich, M. I. The Pribram, Lost City, Innisfree, and Neuschwanstein falls: An analysis of the atmospheric trajectories. Solar System Research.42, 372-390. 2008.[5] Gritsevich, M.I., Stulov, V.P., Turchak, L.I. Consequences of collisions of natural cosmic bodies with the Earth's atmosphere and surface. Cosmic Research vol.50, no.1, 56-64. 2012.[6] Sansom, E.K., Gritsevich, M., Devillepoix, H.A.R., Jansen-Sturgeon, T., Shober, P.,Bland, P.A., Towner, M.C., Cupák, M., Howie, R.M., Hartig, B.A.D. Determining Fireball Fates Using the α-β Criterion. Astrophysical Journal 885(2):115. 2019.[7] Boaca I., Gritsevich M., Birlan M., Nedelcu, A., Boaca, T., Colas, F., Malgoyre, A.,Zanda, B., Vernazza P., to be submitted. 2022.[8] Moilanen, J., Gritsevich, M., Lyytinen, E., Determination of strewn fields for meteorite falls, Monthly Notices of the Royal Astronomical Society 503, 3337-3350. 2021.[9] Boaca I., Nedelcu A., Birlan M., Boaca T., Anghel S. Mathematical model for the dark-flight trajectory of a meteoroid, Romanian Astronomical Journal, Vol. 31, No. 2. 2021
Spectral properties of nine M-type asteroids
No full textReproduced with permission. Copyright ESO. Article published by EDP Sciences and available at http://www.aanda.org.International audienceAims. We present spectroscopic results for nine M-type asteroids (325 Heidelberga, 497 Iva, 558 Carmen, 687 Tinette, 766 Moguntia, 860 Ursina, 909 Ulla, 1280 Baillauda, and 1564 Srbija) in the 0.8−2.5 μm spectral region. One visible spectrum is also presented for the asteroid 497 Iva. These asteroids were observed during several runs between 2003 and 2007, and the main goal was to investigate the NIR spectral region of M-type asteroids. Methods. The data was obtained with SpeX/IRTF in Prism mode and Dolores/TNG in LR-B mode. Spectral analysis was performed by comparing the M-type spectra and the meteorite ones (χ2 approach) and the Modified Gaussian Model. Results. With one exception, the asteroids present positive slopes of the spectra, with no absorption features, in good agreement with the spectra of metallic meteorites. The analysis of the asteroid 766 Moguntia was done by means of χ2, MGM techniques, and the Shkuratov scattering law. We conclude that the mineralogy is dominated by olivine. Its NIR spectrum is similar to those of CO/CV meteorites
M4AST - A Tool for Asteroid Modelling
No full textInternational audienceM4AST (Modelling for asteroids) is an online tool devoted to the analysis and interpretation of reflection spectra of asteroids in the visible and near-infrared spectral intervals. It consists into a spectral database of individual objects and a set of routines for analysis which address scientific aspects such as: taxonomy, curve matching with laboratory spectra, space weathering models, and mineralogical diagnosis. Spectral data were obtained using groundbased facilities; part of these data are precompiled from the literature[1].The database is composed by permanent and temporary files. Each permanent file contains a header and two or three columns (wavelength, spectral reflectance, and the error on spectral reflectance). Temporary files can be uploaded anonymously, and are purged for the property of submitted data. The computing routines are organized in order to accomplish several scientific objectives: visualize spectra, compute the asteroid taxonomic class, compare an asteroid spectrum with similar spectra of meteorites, and computing mineralogical parameters. One facility of using the Virtual Observatory protocols was also developed.A new version of the service was released in June 2016. This new release of M4AST contains a database and facilities to model more than 6,000 spectra of asteroids. A new web-interface was designed. This development allows new functionalities into a user-friendly environment. A bridge system of access and exploiting the database SMASS-MIT (http://smass.mit.edu) allows the treatment and analysis of these data in the framework of M4AST environment.Reference:[1] M. Popescu, M. Birlan, and D.A. Nedelcu, "Modeling of asteroids: M4AST," Astronomy & Astrophysics 544, EDP Sciences, pp. A130, 2012
Asteroid target selection for the new Rosetta mission baseline. 21 Lutetia and 2867 Steins
No full textThe new Rosetta mission baseline to the comet 67P/Churyumov-Gerasimenko includes two asteroid fly-bys. To help in target selection we studied all the candidates of all the possible scenarios. Observations have been carried out at ESO-NTT (La Silla, Chile), TNG (Canaries), and NASA-IRTF (Hawaii) telescopes, in order to determine the taxonomy of all the candidates. The asteroid targets were chosen after the spacecraft interplanetary orbit insertion manoeuvre, when the available total amount of Δ V was known. On the basis of our analysis and the available of Δ V, we recommended to the ESA Science Working Group the asteroids 21 Lutetia and 2867 Steins as targets for the Rosetta mission. The nature of Lutetia is still controversial. Lutetia's spectral properties may be consistent with a composition similar to carbonaceous chondrite meteorites. The spectral properties of Steins suggest a more extensive thermal history. Steins may have a composition similar to relatively rare enstatite chondrite/achondrite meteorites
Telescope calibration for mobile platforms: first results
No full textInternational audienceNew data are required continuously for improving the ephemerides of Near-Earth Objects (NEOs) and artificial objects orbiting around Earth. Rapid response optical assets are ideal for the accomplishment of surveillance and tracking of these objects. The increasing importance is addressed to space debris because of the increasing of space activities during the last decade. The article continues the development of concept and realization of a mobile optical asset (Birlan et al., 2018) which will be used for both artificial objects and Near-Earth Object observations. Here we present one solution using the same mount for two telescopes pointing simultaneously the same region of the celestial sphere. Observational tests were performed for asteroid 1998NU, artificial satellites Astra 1N, the comet C/2018 Y1(Iwamoto), and the occultation of Trans-Neptunian Object (38628) Huy
Near infra-red spectroscopy of the asteroid 21 Lutetia. I. New results of long-term campaign
No full textReproduced with permission. Copyright ESO. Article published by EDP Sciences and available at http://www.edpsciences.org/aa.International audienceAims. Investigation of the physical nature of the asteroid 21 Lutetia, target of Rosetta mission, is required for the completion of its ground-based science and in the frame of its future fly-by. Monitoring this object is essential in preparing the future encounter with the spacecraft. Methods. The asteroid was observed with SpeX/IRTF in the spectral region 0.9−4.0 μm, in remote observing mode from Meudon, in March 2003 and August 2004. Results. The new spectrum in the range 0.9−2.5 μm confirms the previous results (Birlan et al. 2004), for a neutral trend with a large shallow band around 1 μm. The spectral region around 3 μm is usually considered as a tracer of aqueous alteration of the surface. The 3 μm band in Lutetias' spectrum is shallower than those of hydrated asteroids, and the 2.9 vs. 3.2 ratio reveals a value close to the CV−CO meteorites. The band around 3.1 μm, if it exists in the spectrum of 21 Lutetia, is different from the one present in the spectrum of 1 Ceres, and is lower than 0.5%
Spectrophotometric observations of 4979 Otawara, target of the Rosetta space mission
No full textA physical portrait based on spectral and photometric data of 4979 Otawara, the first asteroid target of the Rosetta mission, is presented. The aim of this work is to investigate the composition of 4979 Otawara and to evaluate its rotation pole orientation. The spectroscopic observations obtained at Palomar 200'' and IRTF telescopes cover the wavelength range 0.4 to 2.5 μ m, and provide a definitive classification of Otawara as S-type asteroid. An analysis of band depths and slopes places Otawara in the space of S(IV) types, and its possible analogy with ordinary chondrite meteorites is investigated. Moreover we present new photometric data, obtained at Asiago Observatory and at the TNG telescope, that allow confirmation of the fast rotational period of 2.707+/-0.005 hours, and a first indication of the spin vector of Otawara
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