Deep-ultraviolet Raman spectra of Mars-relevant evaporite minerals under 248.6 nm excitation

1Joseph Razzell Hollis,1,2Schelin Ireland,1William Abbey,3Rohit Bhartia,1Luther W.Beegle
Icarus (in Press) Link to Article []
1NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States
2University of Hawaii at Mānoa, Mānoa, HI, United States
3Photon Systems Inc., Covina, CA, United States
Copyright Elsevier

We have measured the deep-ultraviolet (DUV) Raman spectra of a number of evaporite minerals that are relevant to lacustrine and fluvial environments found on Earth and Mars, and show that DUV Raman can provide detailed information on elemental composition and crystal structure. The minerals included three borates, eight carbonates, and seven sulfates, with each class of mineral exhibited very distinct spectra under 248.6 nm excitation, dominated by the various internal vibrations of the borate, carbonate or sulfate oxyanion. Peak positions were shifted by markedly lower wavenumbers vs positions reported in the literature for longer wavelengths, a phenomenon we ascribe to the effect of pre-resonance with the oxyanion. Within each class, minerals consisting different metallic cations could be distinguished by the position of the dominant vibrational mode and the relative intensities of the minor modes, ascribed to the electrostatic impact of the cation on the vibrational behavior of the oxyanion. There was also evidence that DUV Raman can reveal minor metallic components even if they are not apparent in XRD, as two of three calcite (CaCO3) samples exhibited a shoulder on the dominant peak consistent with perturbation by Mg. UV absorption by Fe2+/3+ was a major factor in determining measurable signal, with Fe-rich minerals exhibiting weak/undetectable spectra. Understanding the spectra of these evaporite minerals will be essential to interpreting and identifying complex mineral samples using this technique, and represents an important addition to the spectral standards library of DUV Raman spectroscopy.

Characterization of the Ryugu surface by means of the variability of the near-infrared spectral slope in NIRS3 data

1A.Galiano et al. (>10)
Icarus (in Press) Link to Article []
1INAF-IAPS, Rome, Italy
Copyright Elsevier

The Near-Earth Asteroid 162,173 Ryugu (1999 JU3) was investigated by the JAXA Hayabusa2 mission from June 2018 to November 2019. The data acquired by NIRS3 spectrometer revealed a dark surface with a positive near-infrared spectral slope. In this work we investigated the spectral slope variations across the Ryugu surface, providing information about physical/chemical properties of the surface.

We analysed the calibrated, thermally and photometrically corrected NIRS3 data, and we evaluated the spectral slope between 1.9 μm and 2.5 μm, whose values extend from 0.11 to 0.28 and the mean value corresponds to 0.163±0.022. Starting from the mean value of slope and moving in step of 1 standard deviation (0.022), we defined 9 “slope families”, the Low-Red-Slope families (LR1, LR2 and LR3) and the High-Red-Sloped families (HR1, HR2, HR3, HR4, HR5, HR6). The mean values of some spectral parameters were estimated for each family, such as the reflectance factor at 1.9 μm, the spectral slope, the depth of bands at 2.7 μm and at 2.8 μm. A progressive spectral reddening, darkening and weakening/narrowing of OH bands is observed moving from the LR families to the HR families.

We concluded that the spectral variability observed among families is the result of the thermal metamorphism experienced by Ryugu after the catastrophic disruption of its parent body and space weathering processes that occurred on airless bodies as Ryugu, such as impact cratering and solar wind irradiation. As a consequence, the HR1, LR1, LR2 and LR3 families, corresponding to equatorial ridge and crater rims, are the less altered regions on Ryugu surface, which experienced the minor alteration and OH devolatilization; the HR2, HR3, HR4, HR5 families, coincident with floors and walls of impact craters, are the most altered areas, result of the three processes occurring on Ryugu. The strong reddening of the HR6 family (coincident with Ejima Saxum) is likely due to the fine-sized material covering the large boulder.

Flying too close to the Sun – The viability of perihelion-induced aqueous alteration on periodic comets

Icarus (in Press) Link to Article []
1Planetary Materials Group, Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK
2Dipartimento di Scienze della Terra, Università di Pisa, 56126 Pisa, Italy
3CISUP, Centro per l’Integrazione della Strumentazione dell’Università di Pisa, Lungarno Pacinotti 43, 56126 Pisa, Italy
4Impacts and Astromaterials Research Centre, Department of Earth Science and Engineering, Imperial College London, South Kensington, London SW7 2AZ, UK
Copyright Elsevier

Comets are typically considered to be pristine remnants of the early solar system. However, by definition they evolve significantly over their lifetimes through evaporation, sublimation, degassing and dust release. This occurs once they enter the inner solar system and are heated by the Sun. Some comets (e.g. 1P/Halley, 9P/Tempel and Hale-Bopp) as well as chondritic porous cosmic dust – released from comets – show evidence of minor aqueous alteration resulting in the formation of phyllosilicates, carbonates or other secondary phases (e.g. Cu-sulphides, amphibole and magnetite). These observations suggest that (at least some) comets experienced limited interaction with liquid water under conditions distinct from the alteration histories of hydrated chondritic asteroids (e.g. the CM and CR chondrites).

This synthesis paper explores the viability of perihelion-induced heating as a mechanism for the generation of highly localised subsurface liquid water and thus mild aqueous alteration in periodic comets. We draw constraints from experimental laboratory studies, numerical modelling, spacecraft observations and microanalysis studies of cometary micrometeorites. Both temperature and pressure conditions necessary for the generation and short-term (hour-long) survival of liquid water are plausible within the immediate subsurface (<0.5 m depth) of periodic comets with small perihelia (<1.5 A.U.), low surface permeabilities and favourable rotational states (e.g. high obliquities and/or slow rotational periods). We estimate that solar radiant heating may generate liquid water and perform aqueous alteration reactions in 3–9% of periodic comets. An example of an ideal candidate is 2P/Encke which has a small perihelion (0.33 A.U.), a high obliquity and a short orbital period. This comet should therefore be considered a high priority candidate in future spectroscopic studies of comet surfaces. Small quantities of phyllosilicate generated by aqueous alteration may be important in cementing together grains in the subsurface of older dormant comets, thereby explaining observations of unexpectedly high tensile strength in some bodies.

Most periodic comets which currently pass close to the Sun are dormant, having experienced surface heating, significant cometary activity and dust release in the past. These bodies may be responsible for the partially hydrated cometary micrometeorites we find at the Earth’s surface and their aqueous alteration histories may have been produced by perihelion-induced subsurface heating. This is in contrast to radiogenic and impact heating that operated during the early solar system on asteroids. This study has implications for the alteration history of the active asteroid Phaethon, the target of JAXA’s DESTINY+ mission.

JSC-Rocknest: A large-scale Mojave Mars Simulant (MMS) based soil simulant for in-situ resource utilization water-extraction studies

Icarus (in Press) Link to Article []
1GeoControls Systems, Inc – Jacobs JETS Contract at NASA Johnson Space Center, 2101 NASA Pkwy, Houston, TX 77058, USA
2Jacobs JETS Contract at NASA Johnson Space Center, 2101 NASA Pkwy, Houston, TX 77058, USA
3NASA Johnson Space Center, 2101 NASA Pkwy, Houston, TX 77058, USA
4Department of Earth and Environmental, Franklin & Marshall College, Lancaster, PA 17604, USA
Copyright Elsevier

The Johnson Space Center-Rocknest (JSC-RN) simulant was developed in response to a need by NASA’s Advanced Exploration Systems (AES) In-Situ Resource Utilization (ISRU) project for a simulant to be used in component and system testing for water extraction from Mars regolith. JSC-RN was designed to be chemically and mineralogically similar to material from the aeolian sand shadow named Rocknest in Gale Crater, particularly the 1–3 wt% low temperature (<450 °C) water release as measured by the Sample Analysis at Mars (SAM) instrument on the Curiosity rover. Sodium perchlorate, goethite, pyrite, ferric sulfate, regular and high capacity granular ferric oxide, and forsterite were added to a Mojave Mars Simulant (MMS) base in order to match the mineralogy, evolved gases, and elemental chemistry of Rocknest. Mineral and rock components were sent to the United States Geological Survey (USGS) in Denver for mixing. Approximately 800 kg of JSC-RN was sent back to NASA in 5 gal buckets, which were subsampled and characterized. All samples of the USGS-produced simulants had similar evolved gas profiles as a small prototype batch of JSC-RN made in JSC laboratories, with the exception of HCl, and were similar in terms of mineralogy and total chemistry. Also, all JSC-RN subsamples were homogenous and had similar mineralogy, total chemistry, and low-temperature evolved gas profiles as the Rocknest aeolian sand shadow examined with Curiosity‘s instrument suite on Mars. In particular, the low temperature water releases were similar and the amount of water evolved from JSC-RN at <450 °C was similar to the water content of Rocknest based on SAM water peak integrations. Overall, JSC-RN is ideally suited for ISRU studies of water extraction of global martian soil due to its excellent agreement with measured properties of martian soils and its proven feasibility for large-scale production.

Nanophase iron carbides in fine‐grained rims in CM2 carbonaceous chondrites: Formation of organic material by Fischer–Tropsch catalysis in the solar nebula

1Adrian Brearley
Meteoritics & Planetary Science (in Press) Link to Article []
1Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico, 87131 USA
Published by arrangement with John Wiley & Sons

Transmission electron microscope studies of fine‐grained rims in three CM2 carbonaceous chondrites, Y‐791198, Murchison, and ALH 81002, have revealed the presence of widespread nanoparticles with a distinctive core–shell structure, invariably associated with carbonaceous material. These nanoparticles vary in size from ~20 nm up to 50 nm in diameter and consist of a core of Fe,Ni carbide surrounded by a continuous layer of polycrystalline magnetite. These magnetite shells are 5–7 nm in thickness irrespective of the diameter of the core Fe,Ni carbide grains. A narrow layer of amorphous carbon a few nanometers in thickness is present separating the carbide core from the magnetite shell in all the nanoparticles observed. The Fe,Ni carbide phases that constitute the core are consistent with both haxonite and cohenite, based on electron diffraction data, energy dispersive X‐ray analysis, and electron energy loss spectroscopy. Z‐contrast scanning transmission electron microscopy shows that these core–shell magnetite‐carbide nanoparticles can occur as individual isolated grains, but more commonly occur in clusters of multiple particles. In addition, energy‐filtered transmission electron microscopy (EFTEM) images show that in all cases, the nanoparticles are embedded within regions of carbonaceous material or are coated with carbonaceous material. The observed nanostructures of the carbides and their association with carbonaceous material can be interpreted as being indicative of Fischer–Tropsch‐type (FTT) reactions catalyzed by nanophase Fe,Ni metal grains that were carburized during the catalysis reaction. The most likely environment for these FTT reactions appears to be the solar nebula consistent with the high thermal stability of haxonite and cohenite, compared with other carbides and the evidence of localized catalytic graphitization of the carbonaceous material. However, the possibility that such reactions occurred within the CM parent body cannot be excluded, although this scenario seems unlikely, because the kinetics of the reaction would be extremely slow at the temperatures inferred for CM asteroidal parent bodies. In addition, carbides are unlikely to be stable under the oxidizing conditions of alteration experienced by CM chondrites. Instead, it is most probable that the magnetite rims on all the carbide particles are the product of parent body oxidation of Fe,Ni carbides, but this oxidation was incomplete, because of the buildup of an impermeable layer of amorphous carbon at the interface between the magnetite and the carbide phase that arrested the reaction before it went to completion. These observations suggest that although FTT catalysis reactions may not have been the major mechanism of organic material formation within the solar nebula, they nevertheless contributed to the inventory of complex insoluble organic matter that is present in carbonaceous chondrites.

Study of the Chelyabinsk Meteorite Magnetism by Nuclear Gamma-Resonance Spectroscopy

1Guseynov, M.M.,2Taskaev, S.V.,1Kamilov, I.K.
Crystallography Reports 65, 333-337 Link to Article [DOI: 10.1134/S1063774520030116]
1Amirkhanov Institute of Physics, Dagestan Scientific Center, Russian Academy of Sciences, Makhachkala, 367015, Russian Federation
2Chelyabinsk State University, Chelyabinsk, 454001, Russian Federation

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Monitoring of Spatiotemporal Variations in the Production Rates of Cosmogenic Radionuclides in Chondrites of Different Orbits Falling to Earth

1Ustinova, G.K.,1Alexeev, V.A.
Geochemistry International 58, 487-499 Link to Article [DOI: 10.1134/S0016702920050110]
1Vernadsky Institute of Geochemistry and Analytical Chemistry (GEOKhI), Russian Academy of Sciences, Moscow, 119991, Russian Federation

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Insights into the chemical diversity of the martian mantle from the Pb isotope systematics of shergottite Northwest Africa 8159

1Bellucci, J.J.,2Herd, C.D.K.,1Whitehouse, M.J.,1,3Nemchin, A.A.,1Kenny, G.G.,1Merle, R.E.
Chemical Geology 545, 119638 Link to Article [DOI: 10.1016/j.chemgeo.2020.119638]
1Department of Geosciences, Swedish Museum of Natural History, Stockholm, SE-104 05, Sweden
2Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada
3School of Earth and Planetary Sciences (EPS), Curtin University, Perth, WA 6845, Australia

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Combined micro X-ray fluorescence and micro computed tomography for the study of extraterrestrial volcanic rocks. The case of North West Africa (NWA) 8657: A shergottite martian meteorite

1Porfido, C.,2Manzari, P.,1Allegretta, I.,1Terzano, R.,3De Pascale, O.,3Senesi, G.S.
Talanta 217, 121114 Link to Article [DOI: 10.1016/j.talanta.2020.121114]
1Dipartimento di Scienze del Suolo, della Pianta e degli Alimenti, Università degli Studi di Bari “Aldo Moro”, Via Amendola 165/A, Bari, 70126, Italy
2Agenzia Spaziale Italiana, via del Politecnico, Roma, 00133, Italy
3CNR – Istituto per la Scienza e Tecnologia dei Plasmi (ISTP) – Sede di Bari, Via Amendola 122/D, Bari, 70126, Italy

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Shock-synthesized quasicrystals

1,2Nemeth, P.
IUcrJ 7, 368-369 Link to Article [DOI: 10.1107/S2052252520005254]
1Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Magyar tudósok körútja 2, Budapest, 1117, Hungary
2Department of Earth and Environmental Sciences, University of Pannonia, Egyetem út 10, Veszprém, 8200, Hungary

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