¹Paolo A.Sossi,¹Peter M.E.Tollan,²James Badro,³Dan J.Bower
Earth and Planetary Science Letters 601, 117894 Link to Article [https://doi.org/10.1016/j.epsl.2022.117894]
¹Institute of Geochemistry and Petrology, ETH Zürich, 8092 Zürich, Switzerland
²Institut de Physique du Globe de Paris, Université de Paris, 75005 Paris, France
³Center for Space and Habitability, Universität Bern, 3012 Bern, Switzerland
Copyright Elsevier

Atmospheres are products of time-integrated mass exchange between the surface of a planet and its interior. On Earth and other planetary bodies, magma oceans likely marked significant atmosphere-forming events, during which both steam- and carbon-rich atmospheres may have been generated. However, the nature of Earth’s early atmosphere, and those around other rocky planets, remains unclear for lack of constraints on the solubility of water in liquids of appropriate composition. Here we determine the solubility of water in 14 peridotite liquids, representative of Earth’s mantle, synthesised in a laser-heated aerodynamic levitation furnace. We explore oxygen fugacities (fO2) between −1.9 and +6.0 log units relative to the iron-wüstite buffer at constant temperature (2173 ± 50 K) and total pressure (1 bar). The resulting fH2O ranged from nominally 0 to 0.027 bar and fH2 from 0 to 0.064 bar. Total H2O contents were determined by transmission FTIR spectroscopy of doubly-polished thick sections from the intensity of the absorption band at 3550 cm−1 and applying the Beer-Lambert law. The mole fraction of water in the liquid is found to be proportional to (fH2O)0.5, attesting to its dissolution as OH. The data are fitted by a solubility coefficient of 524 ± 16 ppmw/bar0.5, given a molar absorption coefficient, , of 6.3 ± 0.3 m2/mol for basaltic glasses or 647 ± 25 ppmw/bar0.5, for a preliminary m2/mol for peridotitic glasses. These solubility constants are roughly 10 – 25% lower than those for basaltic liquids at 1623 K and 1 bar. Higher temperatures result in lower water solubility in silicate melts, wholly offsetting the greater depolymerisation of peridotite melts that would otherwise increase H2O solubility relative to basaltic liquids at constant temperature. Because the solubility of water remains high relative to that of CO2, steam atmospheres are rare, although they may form under moderately oxidising conditions on telluric bodies, provided sufficiently high H/C ratios prevail.

¹Michael W. Broadley,^1,2David V. Bekaert,¹Laurette Piani,¹Evelyn Füri,¹Bernard Marty
Nature 611, 245-255 Link to Article [DOI https://doi.org/10.1038/s41586-022-05276-x]
¹Université de Lorraine, CNRS, CRPG, Nancy, France
²Woods Hole Oceanographic Institution, Woods Hole, MA, USA

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

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.

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.

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

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

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.

^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.

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.

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.

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.