¹S. Potin,¹P. Beck,¹L. Bonal,¹B. Schmitt,²A. Garenne,³F. Moynier,⁴A. Agranier,^5,6P. Schmitt‐Kopplin,⁷A. K. Malik,¹E. Quirico
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13540]
¹Institut de Planétologie et d’Astrophysique de Grenoble IPAG, Université Grenoble Alpes, CNRS, 414 rue de la Piscine, 38400 Saint‐Martin d’Hères, France
²Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California, 94550 USA
³Institut de Physique du Globe de Paris, Université de Paris, CNRS, 1 rue Jussieu, 75005 Paris, France
⁴Laboratoire Géosciences Océan, UMR/CNRS 6538, IUEM, Université de Bretagne Occidentale, Technopôle Brest‐Iroise, Rue Dumont d’Urville, 29280 Plouzané, France
⁵Helmholtz Zentrum Muenchen, Research Unit Environmental Simulation (EUS) Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany
⁶Lehrstuhl für Analytische Lebensmittechemie, Technische Universität München, Maximus‐von‐Imhof‐Forum 2, 85354 Freising, Germany
⁷Department of Chemistry, Punjabi University, Patiala, 147 002 Punjab, India
Published by arrangement with John Wiley & Sons

We present here several laboratory analyses performed on the freshly fallen Mukundpura CM chondrite. Results of infrared transmission spectroscopy, thermogravimetry analysis, and reflectance spectroscopy show that Mukundpura is mainly composed of phyllosilicates. The rare earth trace elements composition and ultrahigh‐resolution mass spectrometry of the soluble organic matter give results consistent with CM chondrites. Finally, Raman spectroscopy shows no signs of thermal alteration of the meteorite. All the results agree that Mukundpura has been strongly altered by water on its parent body. Comparison of the results obtained on the meteorite with those of other chondrites of known petrologic types leads to the conclusion that Mukundpura is similar to CM1 chondrites, which differ from its original classification as a CM2.

¹Kennington, A.R.L. et al. (>10)
Physical Review Letters 124, 252702 Link to Article [DOI: 10.1103/PhysRevLett.124.252702]
¹Department of Physics, University of Surrey, Guildford, GU2 7XH, United Kingdom

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^1,2,3,4Lin, M.,⁴Thiemens, M.H.
Geochemistry, Geophysics, Geosystems 21, Article number e2020GC009051 Link to Article [DOI: 10.1029/2020GC009051]
¹State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China
²University of Chinese Academy of Sciences, Beijing, China
³Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
⁴Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, United States

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^1,2,3Liu, Y.,^1,2,3Xue, D.,^1,2,3Li, W.,^1,2Li, C.,^1,2Wan, B.
Microchemical Journal 158, 105221 Link to Article [DOI: 10.1016/j.microc.2020.105221]
¹State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China
²Innovation Academy for Earth Science, Chinese Academy of Sciences, Beijing, 100029, China
³College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China

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¹A.A.Fraeman et al. (>10)
Journal of Geophysical Research, Planets (in Press) Link to Article [https://doi.org/10.1029/2019JE006294]
¹Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
Published by arrangement with John Wiley & Sons

Visible/short‐wave infrared spectral data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) show absorptions attributed to hematite at Vera Rubin ridge (VRR), a topographic feature on northwest Mt. Sharp. The goals of this study are to determine why absorptions caused by ferric iron are strongly visible from orbit at VRR, and to improve interpretation of CRISM data throughout lower Mt. Sharp. These goals are achieved by analyzing coordinated CRISM and in situ spectral data along the Curiosity Mars rover’s traverse. VRR bedrock within areas that have the deepest ferric absorptions in CRISM data also have the deepest ferric absorptions measured in situ . This suggests strong ferric absorptions are visible from orbit at VRR because of the unique spectral properties of VRR bedrock. Dust and mixing with basaltic sand additionally inhibit the ability to measure ferric absorptions in bedrock stratigraphically below VRR from orbit. There are two implications of these findings: (1) Ferric absorptions in CRISM data initially dismissed as noise could be real, and ferric phases are more widespread in lower Mt. Sharp than previously reported, (2) Patches with the deepest ferric absorptions in CRISM data are, like VRR, reflective of deeper absorptions in the bedrock. One model to explain this spectral variability is late‐stage diagenetic fluids that changed the grain size of ferric phases, deepening absorptions. Curiosity’s experience highlights the strengths of using CRISM data for spectral absorptions and associated mineral detections, and the caveats in using these data for geologic interpretations and strategic path planning tools.

¹A.A.Fraeman et al. (>10)
Journal of Geophysical Research, Planets (in Press) Link to Article [https://doi.org/10.1029/2020JE006527]
¹Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
Published by arrangement with John Wiley & Sons

This paper provides an overview of the Curiosity rover’s exploration at Vera Rubin ridge and summarizes the science results. Vera Rubin ridge (VRR) is a distinct geomorphic feature on lower Aeolis Mons (informally known as Mt. Sharp) that was identified in orbital data based on its distinct texture, topographic expression, and association with a hematite spectral signature. Curiosity conducted extensive remote sensing observations, acquired data on dozens of contact science targets, and drilled three outcrop samples from the ridge, as well as one outcrop sample immediately below the ridge. Our observations indicate that strata composing VRR were deposited in a predominantly lacustrine setting and are part of the Murray formation. The rocks within the ridge are chemically in family with underlying Murray formation strata. Red hematite is dispersed throughout much of the VRR bedrock, and this is the source of the orbital spectral detection. Gray hematite is also present in isolated, gray‐colored patches concentrated towards the upper elevations of VRR, and these gray patches also contain small, dark Fe‐rich nodules. We propose that VRR formed when diagenetic event(s) preferentially hardened rocks, which were subsequently eroded into a ridge by wind. Diagenesis also led to enhanced crystallization and/or cementation that deepened the ferric‐related spectral absorptions on the ridge, which helped make them readily distinguishable from orbit. Results add to existing evidence of protracted aqueous environments at Gale crater and give new insight into how diagenesis shaped Mars’ rock record.

¹N. G. Rudraswami,²Matthew J. Genge,³Yves Marrocchi,³Johan Villeneuve,⁴S. Taylor
Journal of Geophysical Research, Planets (in Press) Link to Article [https://doi.org/10.1029/2020JE006414]
¹National Institute of Oceanography (Council of Scientific and Industrial Research), Dona Paula, Goa, India
²Department of Earth Science and Engineering, Imperial College London, London, UK
³CRPG, CNRS, Université de Lorraine, UMR 7358, Vandoeuvre‐les‐Nancy, France
⁴Cold Regions Research and Engineering Laboratory, Hanover, New Hampshire, USA
Published by arrangement with John Wiley & Sons

Cosmic spherules are micrometeorites that melt at high altitude as they enter Earth’s atmosphere and their oxygen isotope compositions are partially or completely inherited from the upper atmosphere, depending on the amount of heating experienced and the nature of their precursor materials. In this study, the three oxygen isotope compositions of 137 cosmic spherules are determined using 277 in‐situ analyses by ion probe. Our results indicate a possible correlation between an increasing average δ¹⁸O compositions of silicate dominated (S‐type) spherules along the series scoriaceous<porphyritic<barred<cryptocrystalline<glass17O values of spherules, therefore, are mostly preserved and suggest that ~80% of particles are samples of C‐type asteroids. The genetic relationships between different S‐types can also be determined with scoriaceous, barred and cryptocrystalline‐spherules mostly having low ∆¹⁷O values (≤0‰) mainly derived from CC‐like sources, whilst porphyritic spherules mostly have positive ∆¹⁷O (>0‰) are largely derived from ordinary chondrite (OC)‐like sources related to S (IV)‐type asteroids. Glass and CAT‐spherules have variable ∆¹⁷O values indicating they formed by intense entry heating of both CC and OC‐like materials. I‐type cosmic spherules have a narrow range of δ¹⁷O (~20–25‰) and δ¹⁸O (~38–48‰) values, with ∆¹⁷O (~0‰) suggesting their oxygen is obtained entirely from the Earth’s atmosphere, albeit with significant mass fractionation owing to evaporative heating. Finally, G‐type cosmic spherules have unexpected isotopic compositions demostrate little mass‐fractionation from a CC‐like source. The results of this study provide a vital assessment of the wider population of extraterrestrial dust arriving at the Earth.

¹Reggie L.Hudson,¹Perry A.Gerakines,^1,2Yukiko Y.Yarnall,^1,3Ryan T.Coones
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2020.114033]
¹Astrochemistry Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
²Universities Space Research Association, Greenbelt, MD 20771, USA
³School of Pharmacy, University of Reading, Whiteknights, Reading RG6 6AD, UK
Copyright Elsevier

Infrared (IR) spectra of the hydrocarbon ices C3H8 (propane), C3H6 (propylene, propene), and C3H4 (propyne, methylacetylene) are relevant to the study of the low-temperature chemistry and spectroscopy of objects within and beyond the Solar System, but IR band strengths and absorption coefficients are lacking for these compounds. Here we present new IR spectra of crystalline and non-crystalline forms of C3H8, C3H6, and C3H4. Measurements of ice density and refractive index also are reported, two quantities needed to compute IR absorption coefficients, band strengths, optical constants, and, ultimately, abundances of propane, propylene, and propyne in extraterrestrial environments and in laboratory experiments. Suggestions and interpretations are offered regarding the multiple crystalline forms of propane and propylene observed. Applications and extensions are described.

¹J.Eschrig,¹L.Bonal,¹P.Beck,¹T.J.Prestgard
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2020.114040]
¹Univ. Grenoble Alpes, IPAG, F-38000 Grenoble, France
Copyright Elsevie

Interpretation of spectroscopic data from remote sensing strongly depends on the spectroscopic properties, particle size and temperature of materials present on the observed surface. Spectral indices of silicates, carbonates, sulfates, oxides and chemicals available on public database are commonly obtained at room temperature and pressure. Hitherto, few studies were performed by analyzing the effects of space environment such as low pressure and temperature on spectroscopic features of minerals, mostly focused on near infrared spectral region. In particular, whether temperature can affect spectral properties of minerals such as the peak emissivity position, band area and shape, was advanced decades ago, but a systematic laboratory study on such effects is still missing. This is especially lacking in the mid-infrared region, where laboratory data are almost completely absent. Thus, it is pivotal to acquire spectra in vacuum both at various temperatures and with variable particle sizes, for better simulating space environmental conditions.

Our experimental apparatus at INAF-Astrophysical Observatory of Arcetri allows reflectance measurements in an extended spectral range from VIS to far IR and at temperatures ranging from 64 K to 500 K. We present here a detailed analysis on temperature-dependent variation on mineral and carbonaceous chondrite samples in the spectral range 1500–400 cm⁻¹ (6.6–25 μm in wavelength). Mineral phases and meteorites analyzed are: pyroxene, olivine, serpentine, Tagish Lake (CI2-ungruped), Aguas Zarcas (CM2) and Orgueil (CI1). Samples are prepared with particle sizes <20 μm, <200 μm, and 200–500 μm. Our results show that temperature induces spectral features modifications such as peak position shifts, band area and peak intensity changes. Such modifications are reversible with temperature and the trend of variation is related to the sample composition and hydration level. Moreover, magnitude of temperature-dependent spectroscopic changes is strongly linked with grain size and composition, hence making this type of analysis pivotal for a correct interpretation of data collected by space telescopes and orbital spacecrafts.

¹Mahajan, R.R.
Astrophysics and Space Science 365, 130 Link to Article [DOI: 10.1007/s10509-020-03845-y]
¹Physical Research Laboratory, Ahmedabad, 380009, India

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