Disk transport rates from Ti isotopic signatures of refractory inclusion

1Jan Render,2James F. J. Bryson,3Samuel Ebert,1Gregory A. Brennecka
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.13923]
1Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California, 94550 USA
2Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, OX1 3AN UK
3Institut für Planetologie, University of Münster, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany
Published by arrangement with John Wiley & Sons

The early solar system was a dynamic period during which the formation of early solids set into motion the process of planet building. Although both astrophysical observations and theoretical modeling demonstrate the presence of widespread transport of material, we lack concrete quantitative constraints on timings, distances, and mechanisms thereof. To trace these transport processes, one needs objects of known early formation times and these objects would need to be distributed throughout parent bodies with known accretion times and distances. Generally, these criteria are met by “regular” (i.e., non–fractionated and unidentified nuclear and excluding hibonite-rich) Ca-Al-rich inclusions (CAIs) as these objects formed very early and close to the young Sun and contain distinctive nucleosynthetic isotope anomalies that permit provenance tracing. However, nucleosynthetic isotopic signatures of such refractory inclusions have so far primarily been analyzed in chondritic meteorites that formed within ~4 AU from the Sun. Here, we investigate Ti isotopic signatures of four refractory inclusions from the ungrouped carbonaceous chondrite WIS 91600 that was previously suggested to have formed beyond ~10 AU from the Sun. We show that these inclusions exhibit correlated excesses in 50Ti and 46Ti and lack large Ti isotopic anomalies that would otherwise be indicative of more enigmatic refractory materials with unknown formation ages. Instead, these isotope systematics suggest the inclusions to be genetically related to regular CAIs commonly found in other chondrites that have a broadly known formation region and age. Collectively, this implies that a common population of CAIs was distributed over the inner ~10 AU within ~3.5 Myr, yielding an average (minimum) speed for the transport of millimeter-scale material in the early solar system of ~1 cm s−1.

Life Underground: Investigating Microbial Communities and their Biomarkers in Mars-analog Lava Tubes at Craters of the Moon National Monument and Preserve

1M.M. Weng et al. (>10)
Journal of Geophysical Research (Planets)(in Press) Link to Article [https://doi.org/10.1029/2022JE007268]
1Department of Biology, Georgetown University, Washington, DC, USA
Published by arrangement with John Wiley & Sons

Craters of the Moon National Monument and Preserve (CotM) is a strong terrestrial analog for lava tube formations on Mars. The commonality of its basalt composition to martian lava tubes makes it especially useful for probing how interactions between water, rock, and life have developed over time, and what traces of these microbial communities may be detectable by current flight-capable instrumentation. Our investigations found that secondary mineral deposits within these caves contain a range of underlying compositions that support diverse and active microbial communities. Examining the taxonomy, activity, and metabolic potential of these communities revealed largely heterotrophic life strategies supported by contributions from chemolithoautotrophs that facilitate key elemental cycles. Finally, traces of these microbial communities were detectable by flight-capable pyrolysis and wet chemistry gas chromatography-mass spectrometry methods comparable to those employed by the Sample Analysis at Mars (SAM) instrument aboard the Curiosity rover and the Mars Organic Molecule Analyzer (MOMA) on the upcoming Rosalind Franklin rover. Using a suite of methods for chemical derivatization of organic compounds is beneficial for resolving the greatest variety of biosignatures. Tetramethylammonium hydroxide (TMAH), for example, allowed for optimal resolution of long chain fatty acids. Taken together, these results have implications for the direction of mass spectrometry as a tool for biosignature detection on Mars, as well as informing the selection of sampling sites that could potentially host biosignatures.

A free and open-source solution for Rietveld refinement of XRD data from the CheMin instrument onboard the Mars rover Curiosity

1Nicola Döbelin,2,3Richard Archer,4Valerie Tu
Planetary and Space Science (in Press) Link to Article [https://doi.org/10.1016/j.pss.2022.105596]
1RMS Foundation, Bischmattstrasse 12, 2544, Bettlach, Switzerland
2Laboratory for Atmospheric and Space Physics, 1234 Innovation Drive, Boulder, CO, 80303, USA
3NASA Johnson Space Center, 1601 NASA Parkway, Houston, TX, 77058, USA
4Jacobs JETS at NASA Johnson Space Center, 1601 NASA Parkway, Houston, TX, 77058, USA

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Aqueous sulfate contributions in terrestrial basaltic catchments: Implications for understanding sulfate sources and transport in Meridiani Planum, Mars

1Rhianna D.Moore,1Anna Szynkiewicz
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2022.115342]
1Dept. of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN, United States of America
Copyright Elsevier

The Meridiani Planum region on Mars has extensive sulfate-rich sedimentary deposits (~20 wt% SO42−) that are hypothesized to have formed from regional groundwater upwelling that led to the precipitation of secondary Fe-, Mg-, Ca-sulfate minerals and cementation of basaltic sediments. However, the primary source of sulfur (S) for these abundant secondary sulfate minerals is unclear. Therefore, in this study the contributions of volcanic S via surface water and groundwater were investigated in the terrestrial basaltic analogs of Hawaii and Iceland to determine the importance of active volcanism and climate on S cycling as well as the resulting timescale of aqueous activity in the Meridiani Planum region. SO42− fluxes (contributions) were calculated in metric tons/yr using historical data from online repositories and normalized to the catchment area to determine the SO42− load in metric tons/yr/km2. Our results show that the SO42− load is greatly affected by climate, typically ranging from ~7.3 to 170 metric tons/yr/km2 under wetter conditions and ~ 2.6 to 43 metric tons/yr/km2 under dry conditions. Active S degassing and accompanying S-rich mineralization from current hydrothermal activity greatly increased the SO42− loads (~2.8 to 170 metric tons/yr/km2) compared to non-active catchments (2.6 to 13 metric tons/yr/km2). Younger basaltic bedrock with greater permeability and groundwater-rock interactions was also found to be important, resulting in higher SO42− loads (~26 to 170 metric tons/yr/km2) compared to older, less permeable catchments (~2.6 to 12 metric tons/yr/km2). Based on these terrestrial SO42− loads in Hawaii and Iceland, we calculated a range of possible loads and timescales of SO42− transport in Meridiani Planum under variable environmental conditions. Results show that the smallest SO42− loads and longest timescales would occur in Meridiani under dry, non-volcanically active conditions, typically requiring ~16 to 65 Ma of an active aqueous system, as in the older catchments of Hawaii and Iceland. Conversely, the largest SO42− fluxes and shortest timescales would occur under wet, volcanically active conditions, requiring ~1.0 to 6.9 Ma, as in the younger catchments of Hawaii and Iceland. Our results suggest that moderately wet conditions with some active hydrothermal S input would be needed to transport and deposit the equivalent mass of SO42− currently present in the sulfate-rich deposits of Meridiani Planum.

Bulk composition and thermal evolution constrain the formation of organics in Ceres’ subsurface ocean via geochemical modeling

1,2,3Jack Diab,3Mohit Melwani Daswani,3Julie Castillo-Rogez
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2022.115339]
1Southern Oregon University, 1250 Siskiyou Blvd., Ashland, OR 97520, USA
2University of California Los Angeles, 607 Charles E. Young Drive East. Box 951569, Los Angeles, CA 90095-1569, United States of America
3Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109, USA
Copyright Elsevier

Ceres is the largest object in the asteroid belt and the only dwarf planet in the inner solar system. In 2015, carbon, and organic compounds, were found by the Dawn mission in high abundance in the surface of Ceres. Here, we use thermodynamic modeling with the goal of constraining the speciation, stability, and abundance of organic compounds formed via abiotic reactions in the early subsurface ocean of Ceres and its mud-bearing mantle. We vary environmental conditions such as temperature, pH, reduction potential, solution composition, and pressure to analyze the variables that lead to optimal formation of organics. Primary results predict that in-situ organic production is negligible for most cases in the subsurface ocean if Ceres primarily accreted CI carbonaceous chondrites yet may be more significant if Ceres formed from cometary material. Carbonate concentration is 3–6 orders of magnitude higher than organics in the chondritic models, while a cometary composition favors significant alcohol and carboxylic acid derivative production, among other organic species. Results also indicate that temperature and pH are drivers of organic formation by water-rock equilibrium, with temperature having the greatest effect. Further analysis reveals that a mixture of ≲ 80 wt% CI chondrite and ≳ 20 wt% cometary material is favorable to in situ organic production of reduced organics. Observational constraints from the Dawn mission indicate that our model results could be representative of the organic observations on the surface. While our models favor organic production in Ceres’ ocean with moderate amounts of cometary material, further studies into alternative mechanisms of production and concentration on the surface of Ceres are needed.

Olivine origination in lunar Das crater through three-dimensional numerical simulation

1Huacheng Li,2,6Zongyu Yue,2Yangting Lin,3,6Kaichang Di,1,4Nan Zhang,5,6Jianzhong Liu
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2022.115333]
1Key Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Sciences, Peking University, Beijing 100871, China
2Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
3State Key Laboratory of Remote Sensing Science, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100101, China
4Earth Dynamics Group, School of Earth and Planetary Sciences, Curtin University, Perth, Australia
5Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China
6CAS Center for Excellence in Comparative Planetology, Hefei 230026, China
Copyright Elsevier

Mineral olivine and Mg-rich spinel observed in Das crater were previously attributed to the excavation from the lunar lower crust or even mantle. To test this hypothesis, we developed a three-dimensional hydrocode SALEc to simulate the formation of such an elliptical crater. The hydrocode SALEc was examined and verified by comparing its results with experimental data and another code iSALE-2D. Based on the comparison between our SALEc’s numerical results and observations, we found that Das crater can be formed by an impact with the projectile of 6.0 km in diameter, impact velocity of 10 km/s, and impact angle of 70° relative to the vertical. In the impact, the excavation depth of Das crater is ~3.0 km, much less than the lunar crust thickness, hence the mineral olivine and Mg-rich spinel observed in this crater is unlikely originated from lunar lower crust or mantle. Numerical simulation results also show that some projectile materials can survive in this impact and are distributed in the downrange crater floor. Given the abundant olivine in many asteroids, we propose that olivine observed in Das crater is most probably originated from projectile remnants instead of excavation from the depth.

Simulation of surface regolith gardening and impact associated melt layer production under ns-pulsed laser ablation

1Aleksandra N. Stojic et al. (>10)
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2022.115344]
1Institut für Planetologie, Westfälische Wilhelms-Universität Münster, Wilhelm – Klemm Str. 10, 48149 Münster, Germany
Copyright Elsevier

The effect of surface regolith gardening and melt layer production produced by space weathering (SW) (owing to micrometeorite [according to comment rev#1] bombardment) of surficial regolith layers of airless planetary surfaces was investigated in an experimental setup by using laser-induced ablation of powdered analog material (synthetic Fo100) under vacuum with a ns-pulsed infrared laser. The investigated analog pellets were prepared from the fine fraction (< 1 μm) up to a grain size of 280 μm, which resembles the uppermost regolith surface of many airless planetary bodies. The Fo-powder was pressed into shape to form a pellet. We focused here on nanometer-sized structural modifications that are induced in the relocated grains, sputtered off ejecta material and melt sprinkles that formed away from the craters caused by laser irradiation of the pressed pellet surface. The ejecta particles were redistributed over the entire pellet surface and beyond. The forming sputter film, melt sprinkles and ballistically ejected grains were caught on carbon film grids positioned nearby the craters. The grids were investigated with a transmission electron microscope (TEM) to discern between the distinct deposition types that were formed by ejecta condensate and partially molten ejected nanometer-size analog grains. Apart from a heavily modified pellet surface, we found that deposited droplets are mostly amorphous with minor nanocrystalline subdomains. Eight out of ten droplets show distinct incipient crystallization stages. This indicates at a relatively high amount of amorphous regolith material at the incipient stage of SW for airless bodies, if the regolith is altered via micrometeorite bombardment.

Rock magnetic characterization of returned samples from asteroid (162173) Ryugu: Implications for paleomagnetic interpretation and paleointensity estimation

1Masahiko Sato et al. (>10)
Journal of Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2022JE007405]
1The University of Tokyo, Tokyo, 113-0033 Japan
Published by arrangement with John Wiley & Sons

In this study, systematic rock magnetic measurements and saturation isothermal remanent magnetization (SIRM) paleointensity calibration experiments were conducted for the returned samples from C-type asteroid (162173) Ryugu and two carbonaceous chondrites (Orgueil and Tagish Lake) to evaluate the remanence carriers of the Ryugu sample and its ability as a paleomagnetic recorder. Our magnetic measurements show that Ryugu samples exhibit signatures for framboidal magnetite, coarse-grained magnetite, and pyrrhotite, and that framboidal magnetite is the dominant remanence carrier of Ryugu samples in the middle-coercivity range. The SIRM paleointensity constant was obtained for two Ryugu samples, and the median value was 3318 ± 1038 μT, which is close to the literature’s value based on the average among magnetite, titanomagnetite, pyrrhotite, and FeNi alloys and is widely used for SIRM paleointensity experiments. The paleointensity values estimated using the obtained SIRM paleointensity constant indicate a strong magnetic field of the protoplanetary disk, suggesting that Sun’s protoplanetary disk existed at the disk location of Ryugu’s parent planetesimal when framboidal magnetite precipitated from the aqueous fluid.

The H2O content of the ureilite parent body

1Liam D.Peterson,1Megan E.Newcombe,2Conel M. O’D. Alexander,2Jianhua Wang,3Adam R.Sarafian,4Addi Bischoff,5Sune G.Nielsen
Geochimica et Cosmochimica acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2022.10.036]
1Department of Geology, University of Maryland, College Park, MD 20740, United States
2Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC 20015, United States
3Corning, Corning, NY 14873, USA
4Institut für Planetologie, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany
5NIRVANA Labs, Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02540, United States
Copyright Elsevier

The fate of highly volatile elements (H, C, F, Cl and S) during planetary accretion and differentiation is debated. Recent analyses of water in non-carbonaceous chondrites (RC, OC, EC) and achondrites (angrites, eucrites) have been used to argue that inner solar system parent bodies accreted and retained their highly volatile element budgets from their primary feedstock without substantial loss during accretion, metamorphism and differentiation. An alternative model posits that differentiated inner solar system parent bodies (e.g., the angrite parent body, 4 Vesta, Earth) derived the majority of their water from a carbonaceous chondrite-like source, delivered during the final stages of accretion.

In order to add new constraints to this debate, we have measured water in nominally anhydrous minerals, melt inclusions, and interstitial glass in ureilites, the largest group of primitive achondrites in the terrestrial meteorite collection. Primitive achondrites did not experience global melting and homogenization. Therefore, these meteorites capture part of the transition from chondritic to achondritic parent bodies, allowing us to constrain the fate of water during the earliest stages of differentiation. Our nano-scale secondary ion mass spectrometry (nanoSIMS) analyses allow us to assess the viability of ureilite-like material as a potential source of terrestrial water. Analyses of pigeonite in main group ureilites yield a range of 2.0 – 6.0 µg/g H2O, and analyses of high-Ca pyroxene and glass (glassy melt inclusions and interstitial glass) in the Almahata Sitta ureilitic trachyandesite yield ranges of 13 – 19 µg/g H2O and 44 – 216 µg/g H2O, respectively. Mass balance, incremental melting, and batch melting calculations yield a preferred ureilite parent body H2O content of 2 – 20 µg/g, similar to previous estimates of water in the eucrite parent body (4 Vesta), but lower than estimates of Earth’s water budget. With these data, we demonstrate that 1) the ureilite parent body is H2O-depleted relative to the Earth; 2) ureilite-like material is unlikely to be a primary source of H2O to the Earth; 3) C and H are not necessarily coupled elements during planetary accretion and thermal processing; and 4) accretion, heating, partial melting, and degassing of rocky planetesimals likely results in significant depletion of H2O.

Far-Ultraviolet Photometric Characteristics of JSC-1A and LMS-1 Lunar Regolith Simulants: Comparative Investigations with Apollo 10084

1,2C. J. Gimar,2,1,3U. Raut,2,3M. P. Poston,4A. Stevanovic,5,2S. Protopapa,3T. K. Greathouse,2,1,3K. D. Retherford,2,3J. M. Friday,2,3J. T. Grimes
Journal of Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2022JE007508]
1Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX, 78249 United States
2Center for Laboratory Astrophysics and Space Science Experiments (CLASSE), Space Science and Engineering Division, Southwest Research Institute, San Antonio, TX, 78238 United States
3Space Science and Engineering Division, Southwest Research Institute, San Antonio, TX, 78238 United States
4Kleberg Advanced Microscopy Center, University of Texas at San Antonio, San Antonio, TX, 78249 United States
5Department of Space Studies, Southwest Research Institute, Boulder, CO, 80302 USA
Published by arrangement with John Wiley & Sons

We have characterized the far-ultraviolet (FUV) spectro-photometric response of lunar soil simulants JSC-1A and LMS-1, reporting notable differences from our previous results for Apollo soil 10084 (Raut et al., 2018). While JSC-1A and LMS-1 were designed to emulate the geotechnical and compositional properties of a low-Ti and high-Ti mare soil respectively, these terrestrial simulants lack “space weathering” attributes such as the nanophase iron present in the weathered rims of Apollo grains and glassy agglutinates. Photometric analyses of the JSC-1A phase curves reveal a ∼ 3-4 fold increase in single scattering albedo (SSA) and a forward scattering behavior compared to 10084. LMS-1 is shown to have SSA nearly twice that of 10084 and a near isotropic reflectance. Additionally, both JSC-1A and LMS-1 spectra present a blue slope in the FUV, with the JSC-1A slope ∼ 10× larger than that reported for the 10084 soil. Our analyses imply that low-Ti content, corroborated using energy dispersive x-ray spectroscopy, correlates to brighter FUV reflectance and a greater spectral blue slope for JSC-1A, while space weathering components likely contribute to the backscattering of FUV light by the Apollo soil relative to both simulants. Further work with an extended set of Apollo soils is warranted to deconvolute the relative contributions of weathering and composition to their FUV spectro-photometric response.