¹S.V.S. Murty, ¹P.M. Ranjith, ¹Dwijesh Ray, ¹S. Ghosh, ²Basab Chattopadhyay, ³K.L. Shrivastava
Planetary and Space Science (in Press) Link to Article [http://dx.doi.org/10.1016/j.pss.2016.08.007]
¹Planetary Sciences Division, Physical Research Laboratory, Ahmedabad, India
²Geological Survey of India, Kolkata
³Department of Geology, JNV University, Jodhpur, India

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¹Takaya Nozawa
Planetary and Space Science (in Press) Link to Article [http://dx.doi.org/10.1016/j.pss.2016.08.006]
¹National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan

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¹Elyse Allender, ¹Tomasz F. Stepinski
Icarus (in Press) Link to Article [http://dx.doi.org/10.1016/j.icarus.2016.08.022]
¹Space Informatics Lab, University of Cincinnati, Cincinnati, OH 45221-0131, USA
Copyright Elsevier

Martian spectroscopic and mineralogical analysis is usually performed using Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) browse products – false color images which show the spatial distribution of absorption features at key wavelengths. This manual, time-consuming method is ill-suited for exploratory surveys of a large number of images – for such surveys an automatic methodology is needed. In this paper we propose a method for exploratory but fully automatic mineralogical mapping of CRISM images. In our approach pixels are characterized by vectors of CRISM summary product values instead of spectral functions, and mineralogical units are discovered using a clustering principle. Moreover, the rare class discovery algorithm DEMUD is used in place of a standard clustering algorithm to identify mineralogical units – enabling the identification of only scientifically interesting, possibly rare, mineralogical deposits. The method outputs a map for each site showing the spatial distribution of mineralogical units – areas characterized by similar mineralogy. It also provides, without using a spectral library, semantic labels for each unit. We envision our method as a focus-of-attention tool to facilitate fast exploratory surveys of a large number of images. An analyst needs only to examine manually regions within an image where our pipeline indicates the existence of mineral units of interest. In this paper the method for our computational pipeline is described in detail and its performance is evaluated using a sample of 20 CRISM images – the mineralogical content of which is known from manual analysis. We find that our pipeline identifies most deposits found through manual analysis as well as some additional deposits which were not targeted by those analyses. Overall, we conclude that our fully automatic mineralogical mapper works well for exploratory purposes. Thus, it adds a new, valuable functionality to existing tools for CRISM imagery analysis.

¹N.G. Rudraswami, ¹M. Shyam Prasad, ²R.H. Jones, ³K. Nagashima
Geochimica et Cosmochimica Acta (in Press)   Link to Article [http://dx.doi.org/10.1016/j.gca.2016.08.024]
¹National Institute of Oceanography (Council of Scientific and Industrial Research), Dona Paula, Goa 403004, India
²School of Earth, Atmospheric and Environmental Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
³Hawaii Institute of Geophysics and Planetology, University of Hawaii at Manoa, 1680 East-West-Road, Honolulu, HI 96822, USA
Copyright Elsevier

Cosmic spherules collected from deep sea sediments of the Indian Ocean having different textures such as scoriaceous (4), relict-bearing (16), porphyritic (35) and barred olivine (2) were investigated for petrography, as well as high precision oxygen isotopic studies on olivine grains using secondary ion mass spectrometry (SIMS). The oxide FeO/MgO ratios of large olivines (> 20μm) in cosmic spherules have low values similar to those seen in the olivines of carbonaceous chondrite chondrules, rather than matching the compositions of matrix. The oxygen isotope compositions of olivines in cosmic spherules have a wide range of δ18O, δ17O and Δ17O values as follows: −9 to 40‰, −13 to 22‰ and -11 to 6‰. Our results suggest that the oxygen isotope compositions of the scoriaceous, relict-bearing, porphyritic and barred spherules show provenance related to the carbonaceous (CM, CV, CO and CR) chondrites. The different types of spherules that has experienced varied atmospheric heating during entry has not significantly altered the Δ17O values. However, one of the relict-bearing spherules with a large relict grain has Δ17O = 5.7‰, suggesting that it is derived from 16O-poor material that is not recognized in the meteorite record. A majority of the spherules have Δ17O ranging from −4 to −2‰, similar to values in chondrules from carbonaceous chondrites, signifying that chondrules of carbonaceous chondrites are the major contributors to the flux of micrometeorites, with an insignificant fraction derived from ordinary chondrites. Furthermore, barred spherule data shows that during atmospheric entry an increase in ∼10‰ of δ18O value surges Δ17O value by ∼1‰.

^1,2Shawn D. Domagal-Goldman et al. (>10)*
Astrobiology 16, 8 561-653 Link to Article [doi:10.1089/ast.2015.1460]
¹NASA Goddard Space Flight Center, Greenbelt, Maryland, USA.
²Virtual Planetary Laboratory, Seattle, Washington, USA.
*Find the extensive, full author and affiliation list on the publishers website

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¹M. D’Elia, ¹A. Blanco, ¹A. Galiano, ¹V. Orofino, ¹S. Fonti, ¹F. Mancarella, ²A. Guido, ²F. Russo, ²A. Mastandrea
International Journal of Astrobiology (in Press) Link to Article [ http://dx.doi.org/10.1017/S147355041600015X]
¹Department of Mathematics and Physics ‘Ennio De Giorgi’, University of Salento, Lecce, Italy
²Department of Biology, Ecology and Earth Science, University of Calabria, Cosenza, Italy

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¹R.V. Gough, ²V.F. Chevrier, ¹M.A. Tolbert
Planetary and Space Science (in Press) Link to Article [http://dx.doi.org/10.1016/j.pss.2016.07.006]
¹Department of Chemistry and Biochemistry and Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, 216 UCB, Boulder, CO 80309, USA
²Arkansas Center for Space and Planetary Sciences, University of Arkansas, Fayetteville, AR, USA

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¹S. De Angelis, ¹C. Carli, ¹F. Tosi, ²P. Beck, ²B. Schmitt, ¹G. Piccioni, ¹M.C. De Sanctis, ¹F. Capaccioni, ³T. Di Iorio, ²Sylvain Philippe
Icarus (in Press) Link to Article [http://dx.doi.org/10.1016/j.icarus.2016.07.022]
¹Istituto di Astrofisica e Planetologia Spaziali, INAF-IAPS, Via del Fosso del Cavaliere 100, I-00133 Roma, Italy
²Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), 414 Rue de la Piscine, F-38400 St-Martin d’Hères (France), France
³ENEA Centro Ricerche Casaccia (ENEA SSPT-PROTER-OAC), Via Anguillarese 301, I-00123 Roma, Italy
Copyright Elsevier

We investigate two poly-hydrated magnesium sulfates, hexahydrite (MgSO4 • 6H2O) and epsomite (MgSO4 • 7H2O), in the visible and infrared (VNIR) spectral range 0.5÷4.0 μm, as particulate for three different grain size ranges: 20-50 µm, 75-100 µm and 125-150 µm. All samples were measured in the 93 K to 298 K temperature range. The spectra of these hydrated salts are characterized by strong OH absorption bands in the 1.0-1.5 μm region, and by H2O absorption bands near 2 and 3 μm. Other weak features show up at low temperatures near 1.75 μm (in both hexahydrite and epsomite) and 2.2 μm (only in hexahydrite). The spectral behavior of the absorption bands of these two minerals has been analyzed as a function of both grain size and temperature, deriving trends related to specific spectral parameters such as band center, band depth, band area, and band width. Hydrated minerals, in particular mono- and poly-hydrated sulfates, are present in planetary objects such as Mars and the icy Galilean satellites. Safe detection of these minerals shall rely on detailed laboratory investigation of these materials in different environmental conditions. Hence an accurate spectral analysis of such minerals as a function of temperature is key to better understand and constrain future observations.

¹Norbert Kömle,²Craig Pitcher,²Yang Gao,³Lutz Richter
Icarus (in Press) Link to Article [http://dx.doi.org/10.1016/j.icarus.2016.08.019]
¹Space Research Institute, Austrian Academy of Sciences, Schmiedlstraße 6, A-8042 Graz, Austria
²STAR Lab, Surrey Space Centre, University of Surrey, Guildford, GU2 7XH, UK
³OHB System AG, Manfred-Fuchs-Straße 1, 82234 Weßling – Oberpfaffenhofen, Germany
Copyright Elsevier

The Powdered Sample Dosing and Distribution System (PSDDS) of the ExoMars rover will be required to handle and contain samples of Mars regolith for long periods of time. Cementation of the regolith, caused by water and salts in the soil, results in clumpy material and a duricrust layer forming on the surface. It is therefore possible that material residing in the sampling system may cement, and could potentially hinder its operation. There has yet to be an investigation into the formation of duricrusts under simulated Martian conditions, or how this may affect the performance of sample handling mechanisms. Therefore experiments have been performed to create a duricrust and to explore the cementation of Mars analogues, before performing a series of tests on a qualification model of the PSDDS under simulated Martian conditions.

It was possible to create a consolidated crust of cemented material several millimetres deep, with the material below remaining powder-like. It was seen that due to the very low permeability of the Montmorillonite component material, diffusion of water through the material was quickly blocked, resulting in a sample with an inhomogeneous water content. Additionally, samples with a water mass content of 10% or higher would cement into a single solid piece. Finally, tests with the PSDDS revealed that samples with a water mass content of just 5% created small clumps with significant internal cohesion, blocking the sample funnels and preventing transportation of the material. These experiments have highlighted that the cementation of regolith in Martian conditions must be taken into consideration in the design of sample handling instruments.

¹M.B. Biren, ¹M.C. van Soest, ^1,2J.-A. Wartho, ¹K.V. Hodges, ³J.G. Spray
Earth and Planetary Science Letters 453, 56–66 Link to Article [http://dx.doi.org/10.1016/j.epsl.2016.07.053]
¹Group 18 Laboratories, School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA
²GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstr. 1-3, D-24148 Kiel, Germany
³Planetary and Space Science Centre, University of New Brunswick, 2 Bailey Drive, Fredericton, New Brunswick E3B 5A3, Canada
Copyright Elsevier

The (U–Th)/He method has been applied to constrain the formation ages of the Clearwater West and East impact structures of Quebec, Canada. Zircons were separated from impact melt samples derived from a surface exposure at Clearwater West (32 km diameter), and from a drill core at Clearwater East (26 km diameter). The (U–Th)/He results indicate ages of 280±27 Ma280±27 Ma (2σ , n=7n=7) for Clearwater West, and 450±56 Ma450±56 Ma (2σ , n=8n=8) for Clearwater East. Our (U–Th)/He date for Clearwater West supports the findings of previous Rb–Sr (266±15 Ma266±15 Ma; 2σ) and 40Ar/39Ar (280±4 Ma280±4 Ma and 283.8±2.2 Ma283.8±2.2 Ma, 2σ) impact melt studies. Our (U–Th)/He date for Clearwater East also overlaps with previously published 40Ar/39Ar dating results, which yielded U-shaped spectra, with ‘maximum’ and ‘best-estimate’ dates of ∼ 460–470 Ma. Our results support the contention, previously based solely on 40Ar/39Ar data, that the Clearwater West and East impact structures do not comprise an impact doublet that formed coevally from a binary asteroid pair.