¹William Goode,¹Sascha Kempf,^2,3Jürgen Schmidt
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.pss.2021.105343]
¹LASP, University of Colorado, Boulder, CO, USA
²Institute of Geological Sciences, Freie Universität, Berlin, Germany
³Space Physics and Astronomy Research Unit, University of Oulu, Finland
Copyright Elsevier

Europa and Ganymede are both likely to have subsurface oceans (Carr et al., 1998; Khurana et al., 1998; Kivelson et al., 2000). Young surface features may provide an opportunity to sample material from either a subsurface ocean or bodies of liquid water near the surface (McCord et al., 1999, 2001). Detailed compositional information is of large interest for understanding the evolution, oceanic chemistry, and habitability of these moons. To develop an altitude-dependent model for the detectability of ejecta particle composition originating from surface features of a given size, we simulate detections by a dust analyzer with the capability of measuring compositional makeup on board a spacecraft performing close flybys of Europa and Ganymede (Postberg et al., 2011). We determine the origin of simulated detections of ejecta by backtracking their trajectories to the surface using velocity distributions given in the ejecta cloud model by Krivov et al. (2003). Our model is useful for designing flybys with typical closest approach altitudes, such as the ones planned for NASA’s Europa Clipper mission, where we wish to accurately identify the composition of surface features using a dust analyzer.</sup2,3<>

¹M.A.Barucci et al. (>10)
Astronomy & Astrophysics 637, L4 Link to Article [DOI https://doi.org/10.1051/0004-6361/202038144]
¹LESIA, Observatoire de Paris, Université PSL, CNRS, Université de Paris, Sorbonne Université, 92195 Principal Cedex Meudon, France

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¹W. F. Thi,^1,6S. Hocuk,²I. Kamp,^3,7P. Woitke,²Ch. Rab,⁴S. Cazaux,¹P. Caselli,^5,2M. D’Angelo
Astronomy & Astrophysics 635, A16 Link to Article [https://doi.org/10.1051/0004-6361/201731747]
¹Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse, 85741 Garching, Germany
²Kapteyn Astronomical Institute, University of Groningen, Postbus 800, 9700 AV Groningen, The Netherlands
³SUPA, School of Physics & Astronomy, University of St. Andrews, North Haugh, St. Andrews, KY16 9SS, UK
⁴Faculty of Aerospace Engineering, Delft University of Technology, Delft, The Netherlands
⁵Zernike Institute for Advanced Materials, University of Groningen, PO Box 221, 9700 AE Groningen, The Netherlands
⁶CentERdata, Tilburg University, PO Box 90153, 5000 LE Tilburg, The Netherlands
⁷Centre for Exoplanet Science, University of St Andrews, St Andrews, UK

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¹Javier Cuadros,²Joseph R.Michalski,³Janice L.Bishop,¹Christian Mavris,⁴Saverio Fiore,⁵Vesselin Dekov
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2021.114704]
¹Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK
²Department of Earth Sciences & Laboratory for Space Research, The University of Hong Kong, Hong Kong, China
³SETI Institute, Mountain View, CA 94043, USA
⁴Institute of Methodologies for Environmental Analysis, CNR, Department of Geoenvironmental and Earth Sciences, University of Bari, Via Orabona 4, 70125 Bari, Italy
⁵Department of Marine Resources and Energy, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo 108-8477, Japan
Copyright Elsevier

The cameras on the Pathfinder probe (Imager for Pathfinder) and the rovers Spirit and Opportunity (Panoramic Camera), Curiosity (Mast Camera) and Perseverance (Mast Camera-Z) produce visible-range spectra of limited wavelength resolution but of great target resolution which allows mineralogical analysis of selected areas within martian rocks. Laboratory spectra of relevant specimens were transformed into the spectra corresponding to each of the above cameras to increase our capability to interpret martian spectral data collected in-situ. The focus was on finding spectral features that can be detected by the cameras on Mars and are diagnostic of specific minerals. The samples are a collection of (1) Fe/Mg-phyllosilicates from submarine hydrothermal sites and (2) of rocks from acid alteration environments containing goethite, hematite, jarosite and Fe-bearing chlorite as these minerals are detectable in the extended visible range. Among all the samples, interstratified glauconite-nontronite has the most unique spectral features and should be easily detectable with the rover cameras. The spectral features of talc from Fe-bearing interstratified specimens are described. These data are especially relevant as glauconite and talc have been proposed to be fairly abundant on Mars and their detections are suggested from remote-sensing near-IR data. Several indices are proposed to assess Fe content on the investigated samples as well as mineral concentration of goethite and hematite. Among these indices, the normalized spectral slope in the range 420–600 nm increases with total Fe content for all samples, whether phyllosilicates, oxides or sulphates (R2 = 0.7–0.8). For pure phyllosilicates, the slope from 600 to 1010 nm decreases with increasing octahedral Fe (R2 = 0.75). An index for goethite produced excellent results assessing goethite concentration (R2 = 0.84). Of all cameras, Mast Camera reproduces the spectra with lowest fidelity and generates the poorest correlations between indices and tested variables. The other three cameras perform similarly.

¹Andrea Wenzel,²Justin Filiberto,³Natasha Stephen,⁴Susanne P. Schwenzer,⁵Samantha J. Hammond
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13737]
¹Department of Geology, Southern Illinois University, Carbondale, Illinois, 62901 USA
²Lunar and Planetary Institute, USRA, Houston, Texas, 77058 USA
³Plymouth Electron Microscopy Centre, University of Plymouth, Drake Circus, Plymouth, PL4 8AA UK
⁴AstrobiologyOU, School of Environment, Earth, and Ecosystems Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA UK
⁵School of Environment, Earth, and Ecosystems Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA UK
Published by arrangement with John Wiley & Sons

Northwest Africa 6963 (NWA 6963) is a coarse-grained, gabbroic Martian meteorite that further extends our Martian sample collection, both compositionally and texturally. Gabbroic shergottite NWA 6963 provides direct petrologic evidence of intrusive igneous conditions within the Martian crust. Here, we analyzed geochemical zoning profiles and microstructural-crystallographic information from electron backscattered diffraction of augite and pigeonite to constrain the crystallization history of NWA 6963. Compositional zoning profiles reveal pyroxenes with augite or pigeonite cores mantled by Fe-rich pigeonite rims. Our results suggest complex pyroxene textures and zoning profiles observed in pyroxenes in NWA 6963 are due to pyroxene accumulation from a crystallizing magma in a large intrusive environment (sill or magma chamber); however, without geologic context or companion samples, it is currently impossible to rule out accumulation at the base of a very large (>>100 m) differentiated flow.

¹C. Wöhler,¹A. Grumpe,²M. Bhatt,³A. A. Berezhnoy,³V. V. Shevchenko,²A. Bhardwaj
Astronomy & Astrophysics 630, L7 Link to Article [https://doi.org/10.1051/0004-6361/201935927]
¹Image Analysis Group, TU Dortmund University, Otto-Hahn-Str. 4, 44227 Dortmund, Germany
²Physical Research Laboratory, Ahmedabad 380009, India
³Sternberg Astronomical Institute, Moscow State University, Universitetskij Pr., 13, 119234 Moscow, Russia

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¹M.Ferus et al. (>10)
Astronomy & Astrophysics 630, A127 Link to Article [https://doi.org/10.1051/0004-6361/201935816]
¹J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague 8, Czech Republic

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¹Trygve Prestgard,¹Lydie Bonal,¹Jolantha Eschrig,²Jérôme Gattacceca,²Corinne Sonzogni,¹Pierre Beck
Meteorics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13736]
¹Institut de Planétologie et d’Astrophysique de Grenoble, Université Grenoble Alpes, CNRS CNES, 38000 Grenoble, France
²CNRS, Aix Marseille Univ, IRD, Coll France, INRA, CEREGE, Aix-en-Provence, France
Published by arrangement with John Wiley & Sons

Miller Range (MIL) 07687 is a peculiar carbonaceous chondrite officially classified as a CO3. However, it has been found to display unique petrographic properties that are atypical of this group. Moreover, Raman spectra of its polyaromatic carbonaceous matter do not reflect a structural order consistent with the metamorphic history of a type 3 chondrite. As a result, it has been suggested to be an ungrouped C2 chondrite with CO affinities, although it has not been fully excluded as a CO chondrite. The ambiguity of the meteorite’s classification is the motivation behind the present study. We conclude that MIL 07687 is a unique carbonaceous chondrite with possible affinities to CO, CM, and/or some ungrouped carbonaceous chondrites. The difficulty in classifying this meteorite stems from (1) its heavily weathered nature, which interferes with the interpretation of our oxygen (O-)isotopic measurements; (2) the overlap in the petrographic and O-isotopic descriptions of various COs, CMs, and ungrouped meteorites in the Meteoritical Society Database. Optical and infrared spectra are consistent with the meteorite’s unequilibrated nature and indicate that it is probably mildly aqueously altered. Despite traces of aqueous alteration having previously been described in MIL 07687, this is the first time that the presence of hydrated amorphous silicates is reported. In fact, our results show that its present hydration is beyond that of most CO3s, less than most CM2s, and comparable to primitive CR2s. Consequently, we support the meteorite’s C2-ung label, although a CO2 or CM2 classification cannot be fully excluded.

^1,2Elisabeth Losa-Adams,^1,3Carolina Gil-Lozano,^4,5Alberto G. Fairén,^6,7Janice L. Bishop,⁷Elizabeth B. Rampe,¹Luis Gago-Duport
Nature Astronomy 5, 936–942 Link to Article [DOI https://doi.org/10.1038/s41550-021-01397-x]
¹Departamento de Geociencias Marinas, Universidade de Vigo, Lagoas-Marcosende, Vigo, Spain
²Centro de Investigación Mariña da Universidade de Vigo (CIM-UVIGO), Vigo, Spain
³Laboratoire de Planétologie et Géodynamique de Nantes (LPGN), CNRS/Université de Nantes, Nantes, France
⁴Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Madrid, Spain
⁵Department of Astronomy, Cornell University, Ithaca, NY, USA
⁶SETI Institute, Mountain View, CA, USA
⁷NASA Ames Research Center, Moffett Field, CA, USA

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^1,2Nian Wang,^3,4Guiqin Wang,^1,2Ting Zhang,¹Lixin Gu,¹Chi Zhang,¹Sen Hu,⁵Bingkui Miao,^1,2Yangting Lin
Journal of Geophysical Research (Planets) (In Press) Link to Article [https://doi.org/10.1029/2021JE006847]
¹Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029 China
²University of Chinese Academy of Sciences, Beijing, 100049 China
³State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640 China
⁴CAS Center for Excellence in Comparative Planetology, China
⁵Key Laboratory of Geological Engineering Center of Guangxi Province, Guilin University of Technology, Guilin, 541004 China
Published by arrangement with John Wiley & Sons

The Huoyanshan iron meteorite shower, recently found in the Gobi Desert of Hami, Xinjiang, China, has very high Ni (21.1 wt%) content and low Au (2.0 ppm), Ir (0.02 ppm), Ge (1.7 ppm), and Ga (1.1 ppm) contents, and was classified into IAB-sLH subgroup. The iron has a finest octahedrite structure of Widmanstätten pattern (the intergrowth of kamacite (α) and taenite (γ)) with plessite matrix, and euhedral schreibersite (Sch) crystals exclusively enclosed in kamacite bands. The textural features suggest the following formation process: γ→γ + Sch →γ+ Sch + α, and then γ→α2 + γ. The metallographic cooling rate of Huoyanshan iron was determined to be 3–50 °C/Myr using both the taenite Ni profile-matching and taenite central Ni content methods, with the bandwidths corrected for crystallographic orientation by electron backscatter diffraction (EBSD). The cooling rate of Huoyanshan is consistent with other sLH and confirms the slow cooling history of the IAB low-Au subgroups. The slow cooling rates of non-magmatic irons required immediate re-accretion with a thick brecciated fragments layer in the parent body after the impact melting event. The depleted but unfractionated Re, Os, Ir, Ru, and Pt and the enriched Pd and Au abundances of Huoyanshan iron and other sLH subgroup show complementary feature to that of refractory metal nuggets in Ca-, Al-rich inclusions (CAIs), which could be explained by extracting the metallic Fe-Ni with HSE predominantly remained in CAIs from a CAI-bearing asteroid. The very high Ni content of sLH subgroup suggests a highly oxidized parental asteroid, but non-carbonaceous chondrite based on Mo isotopic compositions (Worsham et al., 2017). We propose that the Huoyanshan iron and other sLH subgroup were produced by impact melting of a LL like and CAI-bearing asteroid, followed by fast burying of thick and porous silicate breccia.