¹M. K. Pandey, ^2,3Y. Nishiyama, ^4,5,6P. Tekely
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13209]
¹Indian Institute of Technology Ropar, Rupnagar, Punjab, India
²RIKEN CLST‐JEOL Collaboration Center, Yokohama, Kanagawa, Japan
³JEOL Resonance Inc., Akishima, Tokyo, Japan
⁴École Normale Supérieure, Paris, France
⁵Sorbonne Université, Paris, France
⁶CNRS, UMR 7203 Laboratoire des Biomolécules, Paris, France
Published by arrangement with John Wiley & Sons

We recorded one‐ and two‐dimensional solid‐state nuclear magnetic resonance spectra of meteoric insoluble organic matter with unprecedented sensitivity and resolution permitting us to reveal unambiguous spectroscopic fingerprints relevant to its molecular and isotopic features. Two‐dimensional 1H‐1H and 1H‐13C correlation experiments have unveiled the spatial proximity between aliphatic and aromatic groups proving a highly branched character of a rigid macromolecular network composed of short aliphatic chains linking together small aromatic units. One‐dimensional 2H and two‐dimensional 1H‐2H correlation spectroscopy delivered evidence of significant reduction in the deuterium enrichment of aromatic species relevant to interstellar processes, proto‐planetary disk chemistry, and to determining the origin of the meteoritic insoluble organic matter. The experimental approach developed in this work opens new perspectives for systematic and nondestructive analysis at the molecular level of meteoritic insoluble organic matter even with a very small amount of sample from some particularly rare chondrites.

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

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