¹R.V.Gough, ²K.M.Primm, ³E.G.Rivera-Valentín, ⁴G.M.Martínez, ¹M.A.Tolbert
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2018.10.034]
¹Department of Chemistry and Biochemistry and Cooperative Institute for Research in Environmental Sciences (CIRES), 216 UCB, University of Colorado, Boulder, CO 80309, USA
²Department of Space Studies, Southwest Research Institute, 1050 Walnut St. #300, Boulder, CO 80302, USA
³Lunar and Planetary Institute, Universities Space Research Association, Houston, TX 77058, USA
⁴Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI 48109, USA
Copyright Elsevier

Water vapor is likely being exchanged between the regolith and the atmosphere on Mars, according to evidence from multiple landing sites (including Gale Crater), satellite measurements and numerical modeling. The mechanism of this exchange is largely unknown but could involve the formation of water frost, the adsorption of thin films of water onto mineral surfaces, or the deliquescence or hydration of salts. Hydration, a solid-solid phase transition during which water molecules are incorporated into a crystal structure in stoichiometric amounts, is possible for many salts found at Gale Crater and elsewhere on Mars. These salts may therefore be acting as a source and sink for water vapor in the Martian regolith. Furthermore, salt hydration state may be used as a marker for the presence of liquid water on present-day Mars. For example, the hydrated, crystalline perchlorate and chloride salts detected at recurring slope lineae (RSL) locations have been proposed to form from liquid brines rather than by experiencing hydration by atmospheric water vapor. Here we use an environmental cell coupled to a Raman microscope to experimentally study the hydration and dehydration of magnesium chloride (MgCl₂), calcium perchlorate (Ca(ClO₄)₂), and calcium chloride (CaCl₂) with the goal of determining which of these salts are capable of experiencing hydration on diurnal time scales. Other potential hydration phase transitions of chlorine-containing salts are thought to be less likely. Specifically, we study the transition between magnesium chloride tetrahydrate and hexahydrate, anhydrous calcium perchlorate and hydrated calcium perchlorate, and calcium chloride dihydrate and hexahydrate. We find that under conditions measured by the REMS instrument at Gale Crater, some chlorine-containing salts can readily hydrate and other salts can readily dehydrate, but no salt system studied here is likely to undergo both processes at the surface on diurnal time scales. With respect to RSL formation, these experiments suggest that atmospheric hydration of these salt systems may be too slow or otherwise not feasible. Hence, hydrated salts formed recently at active RSL locations on Mars may indeed be an indicator of the presence of liquid water.

^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.

Richard W. Carlson¹, Ramon Brasser², Qing-Zhu Yin³, Mario Fischer-Gödde⁴, Liping Qin⁵
Space Science Reviews 2018 214:121 Link to Article [DOI: 10.1007/s11214-018-0554-x]
¹Department of Terrestrial MagnetismCarnegie Institution for ScienceWashingtonUSA
²Earth Life Science InstituteTokyo Institute of TechnologyTokyoJapan
³Department of Earth and Planetary SciencesUniversity of California, DavisDavisUSA
⁴Institut für Geologie und MineralogieUniversity of CologneCologneGermany
⁵CAS Key Laboratory of Crust-Mantle Materials and EnvironmentUniversity of Science and Technology of ChinaHefeiChina

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

^1,2Yang, Y., ²Zhang, X., ³Liu, S.-A., ⁴Zhou, T., ⁴Fan, H., ²Yu, H., ^1,2Cheng, W., ²Huang, F.
Journal of Analytical Atomic Spectroscopy 33, 1777-1783 Link to Article [DOI: 10.1039/c8ja00249e]
¹State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China
²School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
³State Key Laboratory of Geological Process and Mineral Resources, China University of Geosciences, Beijing, 100083, China
⁴State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, Guizhou 550081, China

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

¹Hontsova, S.S., ²Danilenko, I.A., ²Yakovlev, G.A., ²Petrova, E.V., ¹Maksimova, E.M., ¹Nauhatsky, I.A.
AIP Conference Proceedings 2015, 020029 Link to Article [DOI: 10.1063/1.5055102]
¹Department of Theoretical Physics and Solid State, Institute of Physical – Technical, Crimean Federal University, Simferopol, 295007, Russian Federation
²Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002, Russian Federation

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

^1,2Emmal Safi, ²Stephen P.Thompson, ¹Aneurin Evans, ²Sarah J.Day, ²Claire A.Murray, ²Annabelle R.Baker, ¹Joana M.Oliveira, ¹Jacco Th.van Loon
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2018.10.034]
¹Astrophysics Group, Lennard-Jones Laboratories, Keele University, Keele, Staffordshire, ST5 5BG, UK
²Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK
Copyright Elsevier

Water on the present day Martian surface is thought to exist in two thermally distinct sub-surface reservoirs: as ice in the cryosphere and as groundwater located deeper in the crust. These sub-surface environments are thought to contain saline, rather than pure, water and laboratory studies on whether or not clathrate hydrates can form in such environments are lacking. We fill this gap by performing synchrotron radiation X-ray powder diffraction to investigate the formation and evolution of clathrate hydrates in weak chloride solutions at CO₂ pressures, and over temperature ranges, that are similar to those found in the Martian regolith. We have found that clathrate hydrates can form under conditions relevant to the Martian cryosphere, despite the presence of chloride salts. We find that the dissociation temperatures for CO₂ clathrate hydrates formed in saline solutions are depressed by 10–20 K relative to those formed in pure water, depending on the nature of the salt and the CO₂ pressure. We suggest that the inhibiting effect that salts such as MgCl₂, CaCl₂ and NaCl have on clathrate hydrate formation could also be related to the salts’ effect on the formation of the low temperature phase of ice. However, despite the inhibiting effect of the salts, we conclude that the presence of clathrate hydrates should still be possible under conditions likely to exist within the Martian cryosphere.

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

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

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)

We currently do not have a copyright agreement with this publisher and cannot display the abstract here