¹Yu.Shkuratov, ¹Ye.Surkov, ²M.Ivanov, ¹V.Korokhin, ¹V.Kaydash, ³G.Videen, ⁴C.Pieters, ¹D.Stankevich
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2018.11.002]

^{1V.N. Karazin Kharkiv National University, 35 Sumska St, Kharkiv, 61022, Ukraine
2V.I. Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, 19, Kosygin st., 119991 Moscow, Russia
3Space Science Institute, 4750 Walnut St. Suite 205, Boulder CO 80301, USA
4Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912, USA
Copyright Elsevier}

We provide and test a method to obtain significant improvement of available Chandrayaan-1 M3 data. The advance is achieved using the Gaussian λ-convolution of spectra and Fourier filtration of images. The main result is imagery of the reflectance across different wavelengths as well as parameters of 1 μm and 2 μm absorption bands with unprecedented quality. This approach can be particularly useful for further investigations using M3 data, since it produces improved imagery of various lunar surface characteristics. We studied a region comprising a portion of the Aristarchus Plateau, Montes Agricola, and a small part of the mare surface in Ocean Procellarum to the north of Montes Agricola. We found that the lava flows in the area between the Aristarchus Plateau and Montes Agricola have a chemical/mineral composition different in comparison with mare areas to the northwest of the ridge Montes Agricola. We also identified distinct spectral properties of morphologically young craters located on the plateau and mare surface. A correlation diagram for positions of the minima of the 1 μm and 2 μm bands allows a cluster analysis of the region, and we map areas associated with a cluster corresponding to pyroclastic glasses. Relationships between geologic and spectral parameter maps were established.

¹Maksimova, A.A., ²Kamalov, R.V., ^1,3Chukin, A.V., ⁴Felner, I., ¹Oshtrakh, M.I.
Journal of Molecular Structure 1174, 6-11 Link to Article [DOI: 10.1016/j.molstruc.2018.06.040]
¹Department of Experimental Physics, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002, Russian Federation
²Department of Rare Metals and Nanomaterials, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002, Russian Federation
³Department of Theoretical Physics and Applied Mathematics, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002, Russian Federation
⁴Racah Institute of Physics, The Hebrew University, Jerusalem, 91904, Israel

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¹J. Gregory Shellnutt
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2018.11.001]
¹National Taiwan Normal University, Department of Earth Sciences, 88 Tingzhou Road Section 4, Taipei 11677, Taiwan
Copyright Elsevier

The surface rock composition measured by gamma (γ)-ray spectrometry at the Venera 8 landing site has anomalously high Th (6.5 ± 2.2 ppm) and U (2.2 ± 0.7 ppm) concentrations with respect to the material analyzed at other landing sites (Vega 1, Vega 2, Venera 9, Venera 10). A calculated bulk rock composition of Venera 8, constrained by the measured Th, U and K₂O (4.0 ± 1.2 wt%) contents, is similar to silicic to intermediate rocks (diorite/granodiorite) that are typical of terrestrial convergent margins (magnesian, calc-alkalic). In this study, major and trace elemental modeling is applied in order to determine if the calculated whole rock composition of Venera 8 can be derived from a parental magma composition similar to Venusian basalt. The modeling results indicate that polybaric fractional crystallization of a hydrous (H₂O = 0.4 wt%) and relatively oxidizing (ΔFMQ +0.7) parental composition similar to Venera 14 can yield residual silicic liquids that match the calculated Venera 8 whole rock composition. The measured Th and U concentrations can also be reproduced within the data uncertainty. Although Venus lacks modern Earth-style plate tectonics, magnesian, calc-alkalic compositions are common within Archean greenstone belts and some rift settings (Haida Gwaii). Consequently, it is possible that the Venera 8 probe encountered a fragment of crust that resembles a terrestrial greenstone belt.

¹Hiroshi NAGAOKA, ^1,2Nobuyuki HASEBE, ²Masayuki NAITO, ¹Eido SHIBAMURA, ¹Haruyoshi KUNO, ²Miho MIZONE, ³Kyeong Ja KIM
TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN 16, 137-142 Link to Article [https://doi.org/10.2322/tastj.16.137]
¹Research Institute for Science and Engineering, Waseda University
²Schools of Advanced Science and Engineering, Waseda University
³Korean Institute of Geoscience and Mineral Resources (KIGAM)

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¹Kohei Fukuda, ²Wataru Fujiya, ¹Hajime Hiyagon, ³Yoshiki Makino, ¹Naoji Sugiura, ¹Naoto Takahata, ³Takafumi Hirata,⁴Yuji Sano
Geochemical Journal 52, 255-262 Link to Article [https://doi.org/10.2343/geochemj.2.0510]
¹Department of Earth and Planetary Science, The University of Tokyo
²College of Science, Ibaraki University
³Geochemical Research Center, The University of Tokyo
⁴Atmosphere and Ocean Research Institute, The University of Tokyo

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¹Naotaka Tomioka
Nihon Kessho Gakkaishi 60, 2-8 Link to Article [https://doi.org/10.5940/jcrsj.60.2]
¹Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology

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¹Cindy L.Young, ²Michael J.Poston, ³James J.Wray, ²Kevin P.Hand, ²Robert W.Carlson
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2018.10.032]
¹NASA Langley Research Center, Hampton, VA
²Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA
³School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA
Copyright Elsevier

We systematically measured the mid-IR spectra of different mixtures of three silicates (antigorite, lizardite, and pure silica) with varying effective porosities and amounts of darkening agent (iron oxide and carbon). These spectra have broad implications for interpretation of current and future mission data for airless bodies, as well as for testing the capabilities of new instruments. Serpentines, such as antigorite and lizardite, are common to airless surfaces, and their mid-IR spectra in the presence of darkening agents and different surface porosities would be typical for those measured by spacecraft. Silica has been measured in the plumes of Enceladus and presents exciting possibilities for other Saturn-system surfaces due to long-range transport of E-ring material. Results show that the addition of the IR-transparent salt, KBr, to simulate surface porosity affected silicate spectra in ways that were not predictable from linear mixing models. The strengthening of silicate bands with increasing pore space, even when only trace amounts of KBr were added, indicates that spectral features of porous surfaces are more detectable in the mid-IR. Combining iron oxide with the pure silicates seemed to flatten most of the silicate features, but strengthened the reststrahlen band of the silica. Incorporating carbon with the silicates weakened all silicate features, but the silica bands were more resistant to being diminished, indicating silica may be more detectable in the mid-IR than the serpentines. Finally, we show how incorporating darkening agents and porosity provides a more complete explanation of the mid-IR spectral features previously reported on worlds such as Iapetus.

Leon Kocharov¹, Silja Pohjolainen², Mike J. Reiner^3,4, Alexander Mishev⁵, Haimin Wang^6,7, Ilya Usoskin^1,5, and Rami Vainio⁸
Astrophysical Journal Letters 863, L27 Link to Article [DOI: 10.3847/2041-8213/aad86b]
¹National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan
²Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan

The site of Zn production remains an elusive and challenging problem in astrophysics. A large enhancement of the [Zn/Fe] ratios of very metal-poor stars in the Galactic halo suggests the death of short-lived massive stars, i.e., core-collapse supernovae (CCSNe), as one major site for Zn production. Previous studies have claimed that some specific CCSNe can produce Zn in sufficient quantities. However, it remains unclear which models can withstand the critical test of observations. Using a Zn abundance feature similar to that of r-process elements in faint satellite galaxies, we find evidence that Zn production took place through events that are much rarer than canonical CCSNe. This finding can be unified with the implied decrease in the rate of Zn production with an increasing metallicity for Galactic halo stars, which narrows down the major site of Zn production in the early galaxy to magnetorotational SNe (MR-SNe). On the other hand, in the later phase of galactic evolution, we predict that the major Zn-production site switched from MR-SNe to thermonuclear SNe (SNe Ia). According to this scenario, an accumulation of the contributions from two types of SNe eventually led to the solar isotope composition of Zn, which mainly owes ^66,68Zn to MR-SNe and ⁶⁴Zn to SNe Ia triggered by He-detonation. The requirement of Zn production in SNe Ia sheds a new light on the debate concerning the scenario for SN Ia progenitors, suggesting that a He-detonation model might be one major channel for SNe Ia.

^1,4L.Nardi, ^1,2E.Palomba, ^1,3A.Longobardo, ^1,5A.Galiano, ¹F.Dirri
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2018.10.035]
¹INAF-IAPS, Via Fosso del Cavaliere 100, Roma 00133, Italy
²ASI-SSDC, via del Politecnico, Roma 00133, Italy
³Università Parthenope, Dist. Centro Direzionale Isola C4, 80143, Italy
⁴La Sapienza Università di Roma, Piazzale Aldo Moro 5, Roma 00185, Italy
⁵Università degli Studi di Roma Tor Vergata, Via Orazio Raimondo 18, Roma 00173, Italy
Copyright Elsevier

Olivine is one of the main abundant mineral in the Solar System, and the determination of its abundance on a surface may give fundamental information about its evolution. The study of surface distribution of olivine on asteroid (25143) Itokawa through near-Infrared reflectance spectroscopy is a difficult goal because olivine and pyroxene bands centred at 1 μm and 2 μm are not entirely included in Hayabusa/NIRS’ spectral range. In this work, the retrieval of olivine abundance has been performed by applying two different methods: the first one uses some spectral indices to retrieve olivine abundance, whilst the second one consists of the application of the Hapke’s theory in order to create synthetic spectra aimed at fitting a selection of NIRS’ spectra. The analysis performed with the first method brought to an approximately homogeneous distribution of olivine content (60  ±  15% on average) on Itokawa’s surface, with the exception of Sagamihara region, which has a slightly (up to 10%) lower olivine content. The second method brought to an average 60  ±  7.5% olivine content within 5 selected spectra, with the same reduction found in the spectrum from the Sagamihara region. All these values are in agreement with literature values on this topic, especially with the ones retrieved from particles sampled in Muses Sea by the Hayabusa probe.

¹Wen Xiang Xia et al. (>10)
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2018.10.031]
¹Hubei Subsurface Multi-scale Imaging Key Laboratory, Institute of Geophysics and Geomatics, China University of Geosciences, Wuhan, 430074, China
Copyright Elsevier

The major oxides (SiO2, Al2O3, CaO, FeO, MgO, and TiO2) and Mg# are critical for revealing the petrological characteristics of the Moon and for testing models of lunar formation and geologic evolution. There are few high-spatial-resolution (<250 m/pixel) abundance maps for all the six major oxides and Mg# across the Moon. Furthermore, previous studies primarily employed the traditional regression methods to derive oxide contents from optical images, which may influence the inversion accuracies of the lunar chemical compositions. This paper reports the abundance maps of all the six major oxides and Mg# with a high spatial resolution of ∼200 m/pixel and compared them with the ones in the previous works. Neural networks algorithms along with the data from the Interference Imaging Spectrometer (IIM) onboard Chang’E-1 were employed in this paper to derive the abundances of the six oxides. Compared with the traditional linear regression models, the neural networks method suggested in this work is hopeful to better depict the complex nonlinear relations between the spectra and the chemical components, so it may improve the inversion performance of the lunar chemistry.