¹Alice Aléon-Toppani et al. (>10)
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2024.02.006]
¹Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale, 91405 Orsay, France
Copyright Elsevier

In order to better constrain the alteration history of the Ryugu parent body, we performed a multi-analytical study combining scanning electron microscopy, transmission electron microscopy and infrared spectroscopy on sections extracted from the three fragments A0064-FO019, A0064-FO021 and C0002-FO019 returned from Ryugu by the Hayabusa2 space mission. The three sections show large differences in terms of structure, mineralogy and infrared signature. Section A0064-FO019 resembles the major Ryugu lithology with the presence of both fine-grained phyllosilicates (fg-phyllos) with embedded nanosulfides and coarse-grained phyllosilicates (cg-phyllos), whereas section C0002-FO019 belongs to the group of the less altered lithologies with the presence of anhydrous minerals embedded in a partially amorphous matrix. Section A0064-FO021 also belongs to this group but shows two different lithologies, a compact amorphous one and a more porous and very fractured one showing the presence of Na-rich phosphate, calcite and olivine. The two less altered lithologies (sections A0064-FO021 and C0002-FO019) show the presence of numerous mineralogical features similar to those observed in cometary interplanetary dust particles, ultra-carbonaceous Antarctic micrometeorites or in the CM Paris meteorite, i.e. amorphous and partially crystallized matrix with GEMS-like ghosts objects, whisker olivine, phosphide, or FeNi metal. This supports an outer solar system origin common with that of cometary material for the Ryugu parent body. Combined with the results of Nakamura et al., (2022a, 2022b) reporting the presence of a lithology showing the presence of GEMS-like objects, we propose that section C0002-FO019 represents the onset of aqueous alteration of such primitive materials. The cg-phyllos and fg-phyllos of section A0064-FO019, i.e. of the major Ryugu lithology, representing the advanced stage of alteration, exhibit distinctive IR signatures with a higher abundance of oxygen-rich functional groups in the organic matter (OM) from the cg-phyllos. We thus suggest the following chronology of formation and evolution for Ryugu: (1) accretion of highly porous aggregate of GEMS-like units with fine-grained high-temperature anhydrous silicates, (2) onset of alteration with the dissolution of primary nanosulfides and development of amorphous/partially crystallized material in the pores, (3) crystallization of fg-phyllos with a second generation of sulfides, (4) later formation of cg-phyllos devoid of nanosulfides and their associated oxygen-rich OM in a more water-rich environment.

^1,2,3Xiaorong Qin,⁴Jiacheng Liu,^1,2Wei Tan,^1,2,3Hongping He,⁴Joseph Michalski,⁵Yu Sun,⁶Shangying Li,⁴Binlong Ye,^1,2Yiping Yang,⁴Yiliang Li
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2024.116016]

¹CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China
²CAS Center for Excellence in Deep Earth Science, Guangzhou, China
³University of Chinese Academy of Sciences, Beijing, China
⁴Laboratory for Space Research, University of Hong Kong, Hong Kong, China
⁵Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
⁶School of Land Engineering, Chang’an University, Xi’an, China
Copyright Elsevier

The compositional stratigraphy of Al-rich clays overlying Fe/Mg-rich clays on Mars has been viewed as a window to understanding the atmospheric conditions of early Mars. Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) indicates that nontronite is a main component of Fe/Mg-rich clays. However, the role of the ancient climate in the alteration process, which produced and dissolved these phyllosilicates, remains under debate. The present study experimentally modeled the dissolution of nontronite and precipitation of kaolinite in an acidic solution, which enables us to enhance the interpretation of near-infrared remote sensing data from compositional stratigraphy on Mars. The obtained results show that the transformation started from the losses of both tetrahedral Si and interlayer alkali(earth) cations in nontronite, and Fe3+ in the dioctahedral sheet was released and formed hematite with progressive damage of Sisingle bondO tetrahedral sheets. TG analyses also show that the dissolution of nontronite and precipitation of kaolinite led to an increase in metal-OH (metal = Al, Fe3+ and Mg) content and a simultaneous decrease in H2O content. Accordingly, the gradual increasing trend of visible/near-infrared reflectance (VNIR) spectra ratios of BD1400/BD1900 (BD, band depth) in the kaolinized nontronite can be linked to a gradual upward transition from nontronite to a mixture of nontronite and kaolinite, and finally into kaolinite and hematite, by comparing their spectral features at different evolution stages. Such a trend suggests a weathering process known as ferrallitization, i.e., partial leaching of Si and enrichment of Fe3+ and Al3+. The observed weathering process is consistent with a warm and wet climate capable of sustaining acidic liquid water on its surface over extended geological periods.

¹Mingming Zhang,¹Noël Chaumard,¹Céline Defouilloy,²William O. Nachlas,³Donald E. Brownlee,³David J. Joswiak,⁴Andrew J. Westphal,⁴Zack Gainsforth,¹Kouki Kitajima,¹Noriko T. Kita
Geochimica et Cosmochimica acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2024.02.013]
¹WiscSIMS, Department of Geoscience, University of Wisconsin–Madison, Madison, WI 53706, USA
²Eugene Cameron Electron Microprobe Laboratory, Department of Geoscience, University of Wisconsin–Madison, Madison, WI 53706, USA
³Department of Astronomy, University of Washington, Seattle, WA 98195, USA
⁴Space Sciences Laboratory, University of California, Berkeley, California 94720, USA
Copyright Elsevier

We measured oxygen isotope ratios of 16 silicate fragments from seven aerogel tracks (turnip-like type B tracks 77, 149, 172, 191, and 220; carrot-like type A tracks 22 and 175) of the comet 81P/Wild 2 collector from NASA’s Stardust mission using secondary ion mass spectrometry. Thirteen were prepared by ultramicrotomy; three from track 220 were prepared by sputtering resin blocks using a SIMS Kohler beam, a new procedure aiming to mine as many cometary particles encased in aerogel/resin as possible. Combining new and literature results, we recognized that most silicate fragments of individual type B tracks have diverse mineralogy but consistent mass-independent fractionation of oxygen isotopes (Δ17O = δ17O − 0.52 × δ18O) or display negative Δ17O–Mg# relationship like CR chondrules. These observations suggest that their impactors are loosely bound aggregates of unequilibrated materials originating mainly from similar protoplanetary disk regions, resembling the cluster IDP U2-20-GCA. Furthermore, silicate fragments from type A track 22 have almost identical mineralogy and Δ17O values, confirming that its impactor is a single chondrule-like fragment. The terminal particle of type A track 175 is pure forsterite with Δ17O of ∼–23‰.

Six iron-rich fragments of this study have positive oxygen isotope ratios (Δ17O∼+2‰) and ordinary chondrite chondrule-like olivine compositions. Together with five similar fragments in the literature, a unique population (Mg# ≤86) of Wild 2 fragments that resemble chondrules from the inner solar system (O-E-R) chondrites or the outer solar system CH-CB chondrites was identified. The remaining 16O-poor Wild 2 fragments are Mg# ≥79 silicates with Δ17O∼–2‰ and a small amount of Mg# ≤79 silicates with Δ17O∼0‰, which are most consistent with CR chondrite chondrules. Thus, we conclude that in addition to the possible major source of CR chondrite chondrule-like materials, the inner solar system or CH-CB chondrule-like materials are a minor component of comet Wild 2, like the cluster IDP U2-20-GCA.

¹M. J. Burchell,¹P. J. Wozniakiewicz
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14152]
¹Centre for Astrophysics and Planetary Science, School of Physics and Astronomy, University of Kent, Kent, UK
Published by arrangement with John Wiley & Sons

This paper considers how space missions that fly through the plumes known, or suspected, to erupt naturally from some icy ocean worlds (IOW), such as Enceladus, or that aim to intercept icy ejecta from impact cratering processes on such bodies can sample the water and ice within the plumes. The mechanics of how grains (either in the plumes or the ejecta) would interact with a passing spacecraft (i.e., impact speeds, shock pressures, etc.) are introduced. The impact speeds are estimated and vary with both the mass of the IOW and the orbital parameters of a space mission. This can lead to large differences in impact speeds (and hence collection methods) at bodies such as Enceladus and Europa. The implications of these different impact speeds (a few hundred m s−1 to several km s−1, and even greater than 10 km s−1) for the collection of organic materials from the plumes are shown to be significant.

¹Bailiang Liu,^1,2,3Jingnan Guo,¹Mikhail I. Dobynde,⁴Jia Liu,^1,2Yingnan Zhang,^1,2Liping Qin
Journal of Geophysical Research (Planets)(in Press) Open Access Link to Article [https://doi.org/10.1029/2023JE008069]
¹Deep Space Exploration Laboratory/School of Earth and Space Sciences, University of Science and Technology of China, Hefei, PR China
²CAS Center for Excellence in Comparative Planetology, USTC, Hefei, PR China
³Collaborative Innovation Center of Astronautical Science and Technology, Harbin, China
⁴Deep Space Exploration Laboratory, Institute of Deep Space Science, Hefei, China
Published by arrangement with John Wiley & Sons

The nucleosynthetic Cr isotope anomalies provides useful information to trace the source and origin of extraterrestrial samples, but it is usually influenced by high-energy cosmic rays, and evaluating such effect of cosmic rays in lunar samples is especially important. Those cosmic radiation particles (primary particles) can react with lunar materials, creating many secondary particles. Both primary and secondary particles can produce cosmogenic nuclides on the Moon. Radiation Environment and Dose at the Moon (REDMoon) is a novel GEANT4 Monte-Carlo model built to simulate the interactions of space particles with the lunar surface and subsurface content. Using this model, we simulate the production of cosmogenic Cr isotopes (50Cr, 52Cr, 53Cr, 54Cr) at different depths of lunar surface, and compare the contribution of different reactions generating these nuclides. The results suggest that spallation reactions are the most important process producing cosmogenic Cr isotopes. We also analyze the relationship between 53Cr/52Cr and 54Cr/52Cr predicted by our model and compare it with different Apollo samples. As previously studied, we also find an approximate linear relationship between ɛ53Cr and ɛ54Cr, where ɛ53Cr (or ɛ54Cr) is the relative deviation from the standard 53Cr/52Cr ratio (or 54Cr/52Cr ratio), normalized to 1/10,000. Furthermore, we reveal a change of this linear relationship in different depths of lunar surface. Besides, we investigate how the slopes can be influenced by exposure age and the Fe/Cr ratio. With these additional factors carefully considered, the comparison between our modeled results and the measurements is better than previous studies.

¹Matthew Varnam,¹Christopher W. Hamilton,^2,3Igor Aleinov,¹Jessica J. Barnes
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2024.116009]
¹Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Blvd., Tucson, AZ 85716, USA
²Center for Climate Systems Research, Columbia University, New York, NY, USA
³NASA Goddard Institute for Space Studies, New York, NY, USA
Copyright Elsevier

Lunar volcanic volatiles are crucial for understanding eruption dynamics on the Moon as well as the potential formation, life span, and dissipation of a lunar secondary atmosphere. We review literature concerning volatile content, degassing extent, and speciation during the mare eruption period on the Moon from 4.0 to 1.2 Ga, providing a realistic summary of degassed compositions for the traditional volcanic elements C-O-H-S-F-Cl. The most reliable estimates of lunar volcanic volatiles come from high‑titanium (high-Ti) glass beads sampled during the Apollo 17 mission. Analysis of these samples demonstrates that hydrogen is the most abundant element by mole in erupted volcanic gases, so a hydrogen species should be the most abundant molecule in the lunar gas, rather than carbon monoxide. This hydrogen is expected to speciate mostly as H2, rather than H2O, at the predicted oxygen fugacity for lunar magma. This difference is important because H2 more easily escapes from the Moon, whereas H2O could freeze out on the lunar surface, and potentially persist within permanently shadowed regions near the poles. We also find that sulfur, rather than carbon, is the third most abundant element in lunar volcanic gas, after hydrogen and oxygen.

^1,2Chanud N. Yasanayake,¹Brett W. Denevi,³Takahiro Hiroi,⁴Brad. L. Jolliff,¹Anna C. Martin,^3,5Annabelle L. Gao,^6,7Margaret L. Zhang,^8,9Lucas M. Bloom,¹⁰Samuel J. Lawrence
Journal of Geophysical Research (Planets) (in Press) Open Access Link to Article [https://doi.org/10.1029/2023JE008115]
¹Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
²Johns Hopkins University, Baltimore, MD, USA
³Brown University, Providence, RI, USA
⁴Washington University in St. Louis, St. Louis, MI, USA
⁵Marriotts Ridge High School, Marriottsville, MD, USA
⁶University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
⁷Mount Hebron High School, Ellicott City, MD, USA
⁸University of Alabama, Tuscaloosa, AL, USA
⁹Severna Park High School, Severna Park, MD, USA
¹⁰NASA Johnson Space Center, Houston, TX, USA
Published by arrangement with John Wiley & Sons

The lunar surface evolves over time due to space weathering, and the visible–near-infrared spectra of more mature (i.e., heavily weathered) soils are lower in reflectance and steeper in spectral slope (i.e., darker and redder) than their immature counterparts. These spectral changes have traditionally been attributed to the space-weathered rims of soil grains (and particularly nanophase iron therein). However, understudied thus far is the spectral role of agglutinates—the agglomerates of mineral and lithic fragments, nanophase iron, and glass that are formed by micrometeoroid impacts and are ubiquitous in mature lunar soils. We separated agglutinates and non-agglutinates from six lunar soils of varying maturity and composition, primarily from the 125–250 μm size fraction, and measured their visible–near-infrared reflectance spectra. For each soil, the agglutinate spectra are darker, redder, and have weaker absorption bands than the corresponding non-agglutinate and unsorted soil spectra. Moreover, greater soil maturity corresponds to darker agglutinate spectra with weaker absorption bands. These findings suggest that agglutinates (rather than solely the space-weathered rims) play an important role in both the darkening and reddening of mature soils—at least for the size fractions examined here. Comparisons with analog soils suggest that high nanophase iron abundance in agglutinates is likely responsible for their low reflectance and spectrally red slope. Additional studies of agglutinates are needed both to more comprehensively characterize their spectral properties (across size fractions and in mixing with non-agglutinates) and to assess the relative roles of agglutinates and rims in weathering-associated spectral changes.

^1,2J. Martell et al. (>10)
Journal of Geophysical Research (Planets) (in Press) Open Access Link to Article [https://doi.org/10.1029/2023JE008222]
¹Department of Geology, Lund University, Lund, Sweden
²LINXS Institute of Advanced Neutron and X-ray Science, Lund, Sweden
Published by arrangement with John Wiley & Sons

With several upcoming sample return missions, such as the Mars Sample Return Campaign, non-destructive methods will be key to maximizing their scientific output. In this study, we demonstrate that the combination of neutron and X-ray tomography provides an important tool for the characterization of such valuable samples. These methods allow quantitative analyses of internal sample features and also provide a guide for further destructive analyses with little to no sample treatment, which maintains sample integrity, including minimizing the risk of potential contamination. Here, we present and review the results from four case studies of terrestrial impactites and meteorites along with their analytical setup. Using combined X-ray and neutron tomography, a Ni-Fe silicide spherule, that is, projectile material, was located within a Libyan Desert Glass sample and the distribution of hydrous phases was pinpointed in selected impactite samples from the Chicxulub IODP-ICDP Expedition 364 drill core and the Luizi impact structure, as well as in the Miller Range 03346 Martian meteorite.

¹Kathleen C. Benison et al. (>10)
Journal of Geophysical Research (Planets)(in Press) Open Access Link to Article [https://doi.org/10.1029/2023JE008155]
¹Department of Geology and Geography, West Virginia University, Morgantown, WV, USA
Published by arrangement with John Wiley & Sons

The Mars 2020 Perseverance rover has examined and sampled sulfate-rich clastic rocks from the Hogwallow Flats member at Hawksbill Gap and the Yori Pass member at Cape Nukshak. Both strata are located on the Jezero crater western fan front, are lithologically and stratigraphically similar, and have been assigned to the Shenandoah formation. In situ analyses demonstrate that these are fine-grained sandstones composed of phyllosilicates, hematite, Ca-sulfates, Fe-Mg-sulfates, ferric sulfates, and possibly chloride salts. Sulfate minerals are found both as depositional grains and diagenetic features, including intergranular cement and vein- and vug-cements. Here, we describe the possibility of various sulfate phases to preserve potential biosignatures and the record of paleoenvironmental conditions in fluid and solid inclusions, based on findings from analog sulfate-rich rocks on Earth. The samples collected from these outcrops, Hazeltop and Bearwallow from Hogwallow Flats, and Kukaklek from Yori Pass, should be examined for such potential biosignatures and environmental indicators upon return to Earth.

¹Tom Seccull,^2,3Wesley C. Fraser,⁴Dominik A. Kiersz,⁵Thomas H. Puzia
The Planetary Science Journal 5, 42 Open Access Link to Article [DOI 10.3847/PSJ/ad16dd]
¹Gemini Observatory/NSF’s NOIRLab, 670 N. A’ohoku Place, Hilo, HI 96720, USA; tom.seccull@proton.me
²Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada
³Department of Physics and Astronomy, University of Victoria, Victoria, BC V8P 5C2, Canada
⁴Independent Researcher, Belfast, UK
⁵Institute of Astrophysics, Pontificia Universidad Católica de Chile, Av. Vicuña MacKenna 4860, 7820436, Santiago, Chile

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