^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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¹O.Unsalan,²C.Altunayar-Unsalan
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 240, 118590 Link to Article [https://doi.org/10.1016/j.saa.2020.118590]
¹Ege University, Faculty of Science, Department of Physics, 35100 Bornova, Izmir, Turkey
²Ege University, Central Research Testing and Analysis Laboratory Research and Application Center, 35100 Bornova, Izmir, Turkey

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¹Anicia Arredondo,¹Humberto Campins,²Noemi Pinilla-Alonso,^3,4Juliade León,^5,3Vania Lorenzi,^5,6DavidMorat
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2020.114028]
¹Physics Department, University of Central Florida, P.O. Box 162385, Orlando, FL 32816, USA
²Florida Space Institute, University of Central Florida, Orlando, FL 32816, USA
³Instituto de Astrofísica de Canarias, C/Vía Láctea s/n, 38205, La Laguna, Tenerife, Spain
⁴Departamento de Astrofísica, Universidad de La Laguna, 38205 La Laguna, Tenerife, Spain
⁵Fundación Galileo Galilei – INAF, La Palma (TF), Spain
⁶Observatório Nacional, Coordenação de Astronomia e Astrofísica, Rio de Janeiro 20921-400, Brazil
Copyright Elsevier

There are eight primitive asteroid families in the inner main belt. The PRIMitive Asteroid Spectroscopic Survey (PRIMASS) has characterized all eight families using visible spectroscopy, and two of the families at near infrared wavelengths. This work is part of our survey at near infrared wavelengths and adds a third family, Chaldaea, to it. We see a compositional trend with inclination in the lower inclination families, however, the higher inclination families show more complexity. So far, primitive inner belt families appear spectrally similar (but not identical) in the near infrared despite their diversity at visible wavelengths.

We observed 15 objects in the Chaldaea primitive inner belt family using the NASA InfraRed Telescope Facility (IRTF) and the Telescopio Nazionale Galileo (TNG) between January 2017 and February 2020. Our survey shows that the Chaldaea family is spectrally homogeneous in the NIR, similar to what was seen in the other primitive inner belt families in the near infrared. The Chaldaea family spectra have overwhelmingly concave shapes and have red slopes (average slope 0.85 ± 0.42%/1000 Å in the region between 0.95 and 2.3 μm). We compare these new spectra with spectra from the Klio family and find that they are similar at these wavelengths, which is consistent with these two families having originated from the same parent body.

¹Samuel H.Halim,¹Ian A.Crawford,²Gareth S.Collins,³Katherine H.Joy,²Thomas M.Davison
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2020.114026]
¹Department of Earth and Planetary Sciences, Birkbeck, University of London, Malet St., London WC1E 7HX, UK
²Department of Earth Science & Engineering, Imperial College London, Kensington, London SW7 2AZ, UK
³Department of Earth and Environmental Sciences, University of Manchester, Oxford Rd., Manchester M13 9PL, UK
Copyright Elsevier

The history of organic and biological markers (biomarkers) on the Earth is effectively non-existent in the geological record >3.8 Ga ago. Here, we investigate the potential for terrestrial material (i.e., terrestrial meteorites) to be transferred to the Moon by a large impact on Earth and subsequently survive impact with the lunar surface, using the iSALE shock physics code. Three-dimensional impact simulations show that a typical basin-forming impact on Earth can eject solid fragments equivalent to ~10⁻³ of an impactor mass at speeds sufficient to transfer from Earth to the Moon. Previous modelling of meteorite survivability has relied heavily upon the assumption that peak-shock pressures can be used as a proxy for gauging survival of projectiles and their possible biomarker constituents. Here, we show the importance of considering both pressure and temperature within the projectile, and the inclusion of both shock and shear heating, in assessing biomarker survival. Assuming that they survive launch from Earth, we show that some biomarker molecules within terrestrial meteorites are likely to survive impact with the Moon, especially at the lower end of the range of typical impact velocities for terrestrial meteorites (2.5 km s⁻¹). The survival of larger biomarkers (e.g., microfossils) is also assessed, and we find limited, but significant, survival for low impact velocity and high target porosity scenarios. Thermal degradation of biomarkers shortly after impact depends heavily upon where the projectile material lands, whether it is buried or remains on the surface, and the related cooling timescales. Comparing sandstone and limestone projectiles shows similar temperature and pressure profiles for the same impact velocities, with limestone providing slightly more favourable conditions for biomarker survival.