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

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

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

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

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.

¹Yuki Itoh,¹Mario Parente
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2020.114024]
¹Department of Electrical and Computer Engineering, University of Massachusetts, Amherst, United States of America
Copyright Elsevier

We propose a new method to perform atmospheric correction and de-noising on hyperspectral image cubes acquired by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on board NASA’s Mars Reconnaissance Orbiter (MRO). The CRISM imager has had an important role in advancing our understanding of many aspects of Martian mineralogy. Many mineral detections from CRISM data have been facilitated by significant efforts in the development of the CRISM data processing pipeline to retrieve surface reflectance. However, some residuals remain in CRISM spectra after atmospheric correction, causing difficulty in the interpretation of processed reflectance spectra. In addition, CRISM images are occasionally corrupted with high noise levels exhibiting heterogeneous statistical properties. This paper identifies the cause of such spectral distortions and describe a technique that simultaneously performs both atmospheric correction and de-noising for each image cube individually. In particular, our method focuses on the 1.0–2.6 μm wavelength region of CRISM images and is applicable to images of non-icy surfaces. Experimental results show that our technique is able to significantly mitigate noise and distortions from various sources like gaseous absorptions, detector temperature, and water ice aerosols, compared with the atmospheric correction method in the CRISM official processing pipeline called volcano scan correction, for a variety of scenes. Careful validations that include the qualitative examination of noise and artifacts both on ratioed and non-ratioed spectra and comparison using multiple overlapping images strengthen confidence in our approach.

¹Apostolos A.Christou,^1,2Galin Borisov,³Aldo Dell’Oro,⁴Alberto Cellino,⁵Maxime Devogèle
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2020.113994] 
¹Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DG, United Kingdom
²Institute of Astronomy and NAO, 72 Tsarigradsko Chaussée Blvd, Sofia BG-1784, Bulgaria
³INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, Firenze I-50125, Italy
⁴INAF – Osservatorio Astrofisico di Torino, via Osservatorio 20, Pino Torinese 10025, Italy
⁵Lowell Observatory, 1400 W Mars Hill RD, Flagstaff, AZ 86001, USA
Copyright Elsevier

We investigate the mineralogical makeup of L5 Martian Trojan asteroids via reflectance spectroscopy, paying special attention to (101429) 1998 VF₃₁, the only L5 Trojan that does not belong to the Eureka family (Christou, 2013). We find that this asteroid most likely belongs to the Bus-Demeo S-complex, in agreement with Rivkin et al. (2007). We compare it with a variety of solar system bodies and obtain good spectral matches with Sq- or S-type asteroids, with spectra of the lunar surface and of Martian and lunar meteorites. Mixture fitting to spectral endmembers suggests a surface abundance of Mg-rich orthopyroxene and iron metal or, alternatively, a combination of plagioclase and metal with a small amount of Mg-poor orthopyroxene. The metallic component may be part of the intrinsic mineral makeup of the asteroid or an indication of extreme space weathering.

In light of our findings, we discuss a number of origin scenarios for (101429). The asteroid could be genetically related to iron-rich primitive achondrite meteorites (Rivkin et al., 2016), may have originated as impact ejecta from Mars – a scenario proposed recently for the Eureka family asteroids (Polishook et al., 2017) – or could represent a relic fragment of the Moon’s original solid crust, a possibility raised by the asteroid’s close spectral similarity to areas of the lunar surface. If, on the other hand, (101429) is a relatively recent addition to the Martian Trojan clouds (Christou et al., 2020), its origin is probably traced to high-inclination asteroid families in the Inner Main Belt.

For the olivine-dominated Eureka family, we find that the two smaller asteroids in our sample are more spectrally similar to one another than to (5261) Eureka, the largest family member. Spectral profiles of these three asteroids are closely similar shortward of ∼0.7 μ m but diverge at longer wavelengths. For the two smaller asteroids in particular, we find the spectra are virtually identical in the visible region and up to 0.8 μ m. We attribute spectral differences in the near-IR region to differences in either: degree of space weathering, olivine chemical composition and/or regolith grain size.

¹Nan Liu,²Andrew Steele,¹Larry R. Nittler,³Rhonda M. Stroud,³Bradley T. De Gregorio,¹Conel M. O’D. Alexander,¹Jianhua Wang
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13555]
¹Department of Terrestrial Magnetism, Carnegie Institution for Science, Washington, District of Columbia, 20015 USA
²Geophysical Laboratory, Carnegie Institution for Science, Washington, District of Columbia, 20015 USA
³Materials Science and Technology Division, US Naval Research Laboratory, Washington, District of Columbia, 20375–5320 USA
Published by arrangement with John Wiley & Sons

We noticed a few minor errors in Table S2 in the supplement of the original manuscript, as summarized below. (1) The error for the 14N/15N ratio of grain M2‐A4‐G27 should be 0.2 instead of 0.3. (2) The δ30Si value of grain M1‐A5‐G1112 should be 16 instead of 19. (3) The names of grains M2‐A1‐G569 and M2‐A1‐G576 should be M2‐A2‐G569 and M2‐A1‐G576‐2, respectively. This erratum contains the correct data table (Table S2).

In addition, we would like to note that the isotope ratios for grains M1‐A4‐G557 and M2‐A1‐G303 reported in Table S2 are slightly different from those reported in Liu et al. (2017), due to small differences in the adopted regions of interest (ROIs) for data reduction. The use of different ROIs and slightly different normalization approaches also resulted in small differences between the silicon isotope ratios of X grains reported in Table S2 and in Liu et al. (2018). The two sets of data, however, generally overlap with each other within 1σ errors, and the small differences do not affect any of the discussions or conclusions in these papers.