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  • 1
    Publication Date: 2018-07-04
    Description: Publication date: Available online 2 July 2018 Source: Planetary and Space Science Author(s): B. Carry, J. Berthier Preparation of detailed night schedule prior to an observing run can be tedious, especially for solar system objects which coordinates are epoch-dependent. We aim at providing the community with a Web service compliant with Virtual Observatory (VO) standards, to create tables of observing conditions, together with airmass and sky charts, for an arbitrary list of targets. We take advantage of available VO services such as the SIMBAD astronomical database, the Aladin sky atlas, and the Miriade ephemerides generator to build a new service dedicated to the planning of observations. The requests for ephemerides charts and tables are handled by a VO-compliant Web service. For each date, and each target, coordinates in local and equatorial frames are computed, and used to select targets accordingly to user's criteria for visibility. This new service, dubbed ViSiON for Vi sibility S erv i ce for O bserving N ight, is a new method of Miriade Web service hosted at IMCCE. It allows anyone to create graphics of observing conditions and tables summarizing them, provided as PDF, VOTable, and xHTML documents.
    Print ISSN: 0032-0633
    Electronic ISSN: 1873-5088
    Topics: Geosciences , Physics
    Published by Elsevier
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  • 2
    Publication Date: 2018-07-04
    Description: Publication date: Available online 2 July 2018 Source: Planetary and Space Science Author(s): Sandra Pizzarello, Christopher T. Yarnes We analyzed the water extracts of the recently fallen Mukundpura (MK) meteorite and searched for amino-, hydroxy- and carboxylic acids, amines and their possible enantiomeric excesses. All water-soluble compounds detected so far were found to have distributions similar to those identified in Murchison, with the main compositional differences of lower yields overall and absence in MK of longer chain compounds. Enantiomeric excesses were detected in MK for (S) isovaline and (S) sec-butylamine, the compounds that displayed them in several CM and CR chondrites. We also obtained a preliminary survey of MK hydrocarbons by extracting with solvent their water-extracted powders. MK hydrocarbons presented a suite containing far fewer linear species and is dominated by likely contaminants branched alkanes. Given the large variability of abundances and ee values reported so far within and between meteorites, repeat analyses of MK stones will be needed to better evaluate their extent in the new meteorite.
    Print ISSN: 0032-0633
    Electronic ISSN: 1873-5088
    Topics: Geosciences , Physics
    Published by Elsevier
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  • 3
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    Elsevier
    Publication Date: 2018-06-07
    Description: Publication date: 15 September 2018 Source: Planetary and Space Science, Volume 159
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    Electronic ISSN: 1873-5088
    Topics: Geosciences , Physics
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  • 4
    Publication Date: 2018-06-07
    Description: Publication date: 15 September 2018 Source: Planetary and Space Science, Volume 159 Author(s): Edward A. Cloutis, David Hewson, Daniel M. Applin, J.Paul Mann, Stanley A. Mertzman Raman and high-resolution reflectance spectrometers will play an increasingly important role in future surface exploration of Mars. We undertook a study of the 532 nm Raman and 0.35–2.5 μm reflectance spectral properties of a suite of terrestrial serpentinites and related rocks from the Southern Quebec Ophiolite Belt, Canada in order to: (1) determine what factors control the appearance of their Raman and reflectance spectra; and (2) enable more robust analysis of Raman and reflectance observational data for Mars to be provided by future Mars landed missions. We examined the effects of surface texture, presence of weathered surfaces, sample heterogeneity, grain size (whole rock versus powder) on Raman and reflectance spectra, and of integration time on the Raman spectra. The Raman spectra are characterized by strong induced fluorescence, however they usually still allow the strongest peaks of the major silicate phase (serpentine, tremolite-actinolite, or talc) to be identified. The different serpentine polymorphs (antigorite, chrysotile, lizardite) can also normally be identified by differences in some Raman peak positions. Only a few of the accessory phases are recognizable in the Raman spectra. There is no systematic difference relating the presence or absence of Raman peaks between whole rock and powder spectra. Increasing integration time can allow weak Raman peaks to be more confidently recognized. Reflectance spectra are dominated by the numerous absorption bands of serpentine or talc, making these phases easily identifiable, but also making accessory phases difficult to identify. Factors such as tetrahedrally-coordinated Fe 3+ , mixed valence Fe (Fe 2+ /Fe 3+ ), and the presence of octahedrally coordinated Fe 2+ in serpentine can also be recognized. As in the Raman spectra, accessory phases are generally not identifiable in the reflectance spectra due to low abundance, weak absorption bands, or because their absorption bands are overlapped by the stronger hydrated silicate absorption bands. In the reflectance spectra the presence of magnetite can be recognized by a lowering of reflectance and a negatively-sloped spectrum. The presence of other opaque phases may be inferred from a lowering of reflectance. Reflectance spectroscopy is generally superior to Raman spectroscopy for identifying the presence of serpentine because of the aforementioned induced fluorescence seen in some of the Raman spectra. Raman and reflectance spectra do not always allow for identification of the same accessory phases, demonstrating their complementarity for analysis of hydrated silicate-dominated rocks.
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    Electronic ISSN: 1873-5088
    Topics: Geosciences , Physics
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  • 5
    Publication Date: 2018-06-04
    Description: Publication date: Available online 2 June 2018 Source: Planetary and Space Science Author(s): Xiaoyu Liu, Colin McInnes, Matteo Ceriotti This paper investigates two strategies to engineer the capture of one member of a binary asteroid pair by a planetary body after close encounter with that planetary body. It is assumed that the binary pair consists of a smaller minor asteroid in orbit about a larger main asteroid, which encounters a planetary body. In order to develop an engineering model of the problem, first we neglect the mass of the smaller minor asteroid in the binary pair and approximate the model as planar parabolic restricted three-body problem (PPRTBP). Second, the related regularised dynamical equations for the problem are developed. An approximate analytical solution to the problem is then obtained for motion in the vicinity of the main asteroid using the regularised coordinates through a linearized model. This provides insight into the motion of the minor asteroid about the main asteroid, allowing strategies to engineer the capture process to be developed. Based on the topology of the zero velocity curves (ZVCs) for the PPRTBP, we determine the capture region for the problem by developing initial condition maps (ICMs) and investigate the details of the dynamical process for capture. Two capture strategies are then proposed to engineer and extend the possibility for capture of the minor asteroid in binary pair. One is a re-phasing manoeuvre before encounter, which guarantees that the particle is within the capture region of the ICMs. The other is an optimal, single-impulse transfer during encounter to ensure transfer through the ZVC bottleneck and capture of the minor asteroid by the planetary body. The purpose of the paper is to explore such engineering strategies, rather than to provide new insights into natural capture dynamics.
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    Electronic ISSN: 1873-5088
    Topics: Geosciences , Physics
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  • 6
    Publication Date: 2018-06-04
    Description: Publication date: Available online 2 June 2018 Source: Planetary and Space Science Author(s): Toshihiko Kadono, Ayako I. Suzuki, Shin-ichi Araki, Takumi Asada, Ryo Suetsugu, Sunao Hasegawa We carried out impact experiments using cylindrical gypsum targets with various radii and investigated the crater on the top (flat) surface. At a ratio of projectile and target radii ∼1/20, the crater size abruptly increases; the spallation extends to the side surface of the targets. The results are closely similar to the previous ones on the curved surfaces. A shock wave propagation model, introduced by Suzuki et al. (2018, Icarus 301, 1–8), can represent such results as the steep increase of the size of the spallation zone in both cases of spherical and cylindrical targets. Using this model, the maximum fragment size is evaluated and agrees well with the experimental results. We found that the enlargement of the spallation zone is crucial to the transition from cratering to catastrophic disruption. We also carried out numerical calculations with iSALE code capable of simulating impact processes in solid materials. The maximum pressure distribution shows that the most parts of the spallation zone are not metamorphosed by shock waves. Also, the crater depth is represented by iSALE without damage models, while the “spallation” seems not to be well reproduced by iSALE even with the damage models.
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    Electronic ISSN: 1873-5088
    Topics: Geosciences , Physics
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  • 7
    Publication Date: 2018-06-03
    Description: Publication date: Available online 2 June 2018 Source: Planetary and Space Science Author(s): Viktor Korokhin, Yuri Velikodsky, Yuriy Shkuratov, Vadym Kaydash, Urs Mall, Gorden Videen All available lunar digital elevation models, e.g., SELENE LALT DEM, SELENE DTM LISM, Chang’E-1 LAM DEM, GLD100, SLDEM2015, have certain disadvantages, including insufficient resolution and/or the presence of defects as well as mismatching reference coordinate systems, making it difficult to incorporate the topographic effect on photometric LROC WAC observations. We here propose a photoclinometry technique that can be used to account for this effect. To do so, we modify our algorithm used to construct seamless photometric mosaics (Korokhin et al., PSS 2016, 122, 70–87) to determine local slopes simultaneously with parameters of photometric function during the mosaicing procedure. This technique can be useful for improvement of quality of remote sensing of surfaces with complex topography. We also develop a new algorithm for constructing the lunar digital elevation model based on the simultaneous use of laser altimetric measurements (LRO LOLA) and local longitudinal slopes obtained photoclinometrically from LROC WAC data. The algorithm provides a digital elevation model with accuracy and resolution not worse than SLDEM2015, yet demonstrating significantly fewer defects and artifacts. High-quality topo data can be useful for geology, geomorphology and for navigation/exploration/mission planning.
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    Electronic ISSN: 1873-5088
    Topics: Geosciences , Physics
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  • 8
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    Elsevier
    Publication Date: 2018-06-03
    Description: Publication date: 1 September 2018 Source: Planetary and Space Science, Volume 158
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    Electronic ISSN: 1873-5088
    Topics: Geosciences , Physics
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  • 9
    Publication Date: 2018-06-03
    Description: Publication date: Available online 2 June 2018 Source: Planetary and Space Science Author(s): Vincenzo Orofino, Giulia Alemanno, Gaetano Di Achille, Francesca Mancarella The presence of ancient fluvial systems on Mars, known as valley networks, is considered one of the most compelling evidence that liquid water was once stable on the planet's surface. To understand the formation mechanisms of these valleys and to acquire information on the ancient climatic conditions of the planet, we determined the formation time of a sample group of 63 Martian valley networks. Our sample group was divided into two subgroups: valleys with an interior channel (13 valleys); and valleys without visible interior channels (50 valleys). For the first subgroup we estimated the formation time using a method based on the calculation of water and sediment discharges. We assumed four different possibilities: continuous flow; 5% of intermittence, typical of terrestrial humid or sub-humid conditions; 1% as for semiarid or arid environments; and finally, 0.1% for hyper-arid conditions. Once obtained the formation times for each valley we evaluated the erosion rates. Subsequently, the mean erosion rates obtained for the first subgroup of valleys were used to calculate the formation times for the remaining 50 valleys using the ratio between the eroded volume and the erosion rate. For the whole sample group of the fluvial systems, we found formation timescales ranging from 5 × 10 2  yr to 8 × 10 6  yr (with a median of 3 × 10 4  yr) for a continuous sediment flow, while the range is from 1 × 10 4 to 2 × 10 8  yr (median 5 × 10 5  yr) with an intermittence of 5%, from 5 × 10 4 to 8 × 10 8  yr (median 3 × 10 6  yr) with an intermittence of 1%, and from 5 × 10 5 and to 8 × 10 9 yr (median 3 × 10 7 yr) with a 0.1% intermittence. However, based on our results, a continuous sediment flow as well as an intermittence of 0.1% seem unlikely. Plausible values of formation timescales are instead obtained with intermittencies of 5% and 1% corresponding to humid and semiarid/arid environment, respectively. Our results do not allow to discriminate between the two scenarios; on the contrary the scenario of a permanently cold and icy Noachian Mars can be ruled out by our findings.
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    Topics: Geosciences , Physics
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  • 10
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    Elsevier
    Publication Date: 2018-05-26
    Description: Publication date: August 2018 Source: Planetary and Space Science, Volume 157
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    Topics: Geosciences , Physics
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