Comparative Raman and visible near-infrared spectroscopic studies of jarosite endmember mixtures and solid solutions relevant to Mars

1Changqing Liu,1Zongcheng Ling,1,2Fengke Cao,1Jian Chen
Journal of Raman Spectroscopy 48, 1676-1684 Link to Article [DOI: 10.1002/jrs.5286]
1Shandong Provincial Key Laboratory of Optical Astronomy & Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, China
2Department of Earth Sciences, The University of Western Ontario, London, ON, Canada

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Type I and type II residual stress in iron meteorites determined by neutron diffraction measurements

1,2Stefano Caporali, 3Giovanni Pratesi, 4Saurabh Kabra, 2FrancescoGrazzi
Planetary and Space Science (in Press) Link to Article []
1Dipartimento Ingegneria Industriale, Università degli Studi di Firenze, Firenze 50134, Italy
2Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, Sesto Fiorentino 50019, Italy
3Dipartimento di Scienze della Terra, Università degli Studi di Firenze, Firenze 50121, Italy
4Science and Technology Facility Council, ISIS Neutron Source, Didcot OX11 0QX, United Kingdom

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Mineral composition of the Martian Gale and Nili Fossae regions from Mars Reconnaissance Orbiter CRISM images

1Yansong Xue, 1,2Yi Yang, 3Le Yu
Planetary and Space Science (in Press) Link to Article []
1Shanghai Astronomical Observatory, Chinese Academy of Science, Shanghai 200030, China
2University of Chinese Academy of Sciences, Beijing 100049, China
3Center for Earth System Science, Tsinghua University, Beijing 100084, China

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Photometry of Ceres and Occator faculae as inferred from VIR/Dawn data

1A.Langobardo et al. (>10)
Icarus (in Press) Link to Article []
1INAF-IAPS, via Fosso del Cavaliere 100, I-00133 Rome, Italy
Copyright Elsevier

Spectral parameters of Ceres measured by the Dawn/VIR imaging spectrometer are studied as a function of illumination angles, by applying a semi-empirical method based on a statistical analysis of the VIR dataset acquired up to September 2016. The study also focuses on the photometry of the Occator faculae, i.e. the brightest spots of the Ceres surface, showing an albedo up to eight times the Ceres average. The considered semi-empirical approach takes into account the small extension (and hence small dataset) of this region and lays the groundwork to apply scattering models even on such a limited area.

The behavior of Ceres visible and infrared reflectance with phase angle is similar to other asteroids belonging to its same spectral class, i.e. C-type. The depth of the bands at 2.7 μm (phyllosilicates), 3.1 μm (ammonium), 3.4 μm (magnesium carbonates) and the infrared spectral slope linearly increase with phase angle, showing analogies with other asteroids and occurrence of phase reddening. The different behavior of the 3.9 μm band depth (also due to Mg carbonates), independent of illumination angles, could indicate that other carriers contribute to the 3.4 μm band and play a more important role in photometry outside the carbonate deposits.

The phase function of the Occator faculae is much steeper than expected from its high albedo. Mixture of bright and dark material and larger roughness can be at the basis of this result. The phyllosilicate bands show a steeper increase with phase angle with respect to the Ceres average, due to the lower presence of dark materials, and/or again larger roughness. The absence of trends with phase angles of the two carbonate bands and of the spectral slope suggests that carbonates do not produce phase reddening.

Experimental impact cratering: A summary of the major results of the MEMIN research unit

1Thomas Kenkmann et al. (>10)
Meteoritics & Planetary Science (in Press) Link to Article [DOI: 10.1111/maps.13048]
1Albert-Ludwigs-Universität Freiburg, Institut für Geo-und Umweltnaturwissenschaften, Freiburg, Germany
Published by arrangement with John Wiley & Sons

This paper reviews major findings of the Multidisciplinary Experimental and Modeling Impact Crater Research Network (MEMIN). MEMIN is a consortium, funded from 2009 till 2017 by the German Research Foundation, and is aimed at investigating impact cratering processes by experimental and modeling approaches. The vision of this network has been to comprehensively quantify impact processes by conducting a strictly controlled experimental campaign at the laboratory scale, together with a multidisciplinary analytical approach. Central to MEMIN has been the use of powerful two-stage light-gas accelerators capable of producing impact craters in the decimeter size range in solid rocks that allowed detailed spatial analyses of petrophysical, structural, and geochemical changes in target rocks and ejecta. In addition, explosive setups, membrane-driven diamond anvil cells, as well as laser irradiation and split Hopkinson pressure bar technologies have been used to study the response of minerals and rocks to shock and dynamic loading as well as high-temperature conditions. We used Seeberger sandstone, Taunus quartzite, Carrara marble, and Weibern tuff as major target rock types. In concert with the experiments we conducted mesoscale numerical simulations of shock wave propagation in heterogeneous rocks resolving the complex response of grains and pores to compressive, shear, and tensile loading and macroscale modeling of crater formation and fracturing. Major results comprise (1) projectile–target interaction, (2) various aspects of shock metamorphism with special focus on low shock pressures and effects of target porosity and water saturation, (3) crater morphologies and cratering efficiencies in various nonporous and porous lithologies, (4) in situ target damage, (5) ejecta dynamics, and (6) geophysical survey of experimental craters.

Ultraviolet spectral reflectance of carbonaceous materials

1Daniel M. Applin, 1,2Matthew R.M. Izawa, 1Edward A. Cloutis, 3Jeffrey J. Gillis-Davis, 4Karly M. Pitman, 5Ted L. Roush, 6Amanda R. Hendrix, 3Paul G. Lucey
Icarus (in Press) Link to Article []
1Dept. of Geography, University of Winnipeg, 515 Portage Avenue, Winnipeg, Manitoba, Canada R3B 2E9
2Institute for Planetary Materials, Okayama University, 827 Yamada, Misasa, Tottori 682-0193 Japan
3 Hawaii Institute of Geophysics and Planetology, University of Hawaii, 2525 Correa Road, Honolulu, Hawaii 96822
4Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, Colorado 80301 USA
5NASA Ames Research Center, Moffett Field, California, 94035-0001 USA
6Planetary Science Institute, 1700 East Fort Lowell, Suite 106, Tucson, AZ, USA 85719-2395
Copyright Elsevier

A number of planetary spacecraft missions carried instruments with sensors covering the ultraviolet (UV) wavelength range. However, there exists a general lack of relevant UV laboratory data to compare against these planetary surface remote sensing observations in order to make confident material identifications. To address this need, we have systematically analyzed reflectance spectra of carbonaceous materials in the 200-500 nm spectral range, and found spectral-compositional-structural relationships that suggest this wavelength region could distinguish between otherwise difficult-to-identify phases. In particular (and by analogy with the infrared spectral region), large changes over short wavelength intervals in the refractive indices associated with the trigonal sp2 π-π* transition of carbon can lead to Fresnel peaks and Christiansen-like features in reflectance. Previous studies extending to shorter wavelengths also show that anomalous dispersion caused by the σ-σ* transition associated with both the trigonal sp2 and tetrahedral sp3 sites causes these features below λ = 200 nm. The peak wavelength positions and shapes of π-π* and σ-σ* features contain information on sp3/sp2, structure, crystallinity, and powder grain size. A brief comparison with existing observational data indicates that the carbon fraction of the surface of Mercury is likely amorphous and submicroscopic, as is that on the surface of the martian satellites Phobos and Deimos, and possibly comet 67P/Churyumov-Gerasimenko, while further coordinated observations and laboratory experiments should refine these feature assignments and compositional hypotheses. The new laboratory diffuse reflectance data reported here provide an important new resource for interpreting UV measurements from planetary surfaces throughout the solar system, and confirm that the UV can be rich in important spectral information.

Laboratory spectroscopy of meteorite samples at UV-vis-NIR wavelengths: Analysis and discrimination by principal components analysis

1Antti Penttilä, 1Julia Martikainen, 1Maria Gritsevich, 1,2KarriMuinonen
Journal of Quantitative Spectroscopy and Radiative Transfer 206, 189-197 Link to Article []
1Department of Physics, University of Helsinki, P.O. Box 64, FI-00014, Finland
2Finnish Geospatial Research Institute FGI, National Land Survey of Finland, Geodeetinrinne 2, FI-02430 Masala, Finland

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