1
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Sahai N, LaRowe D, Senko JM. Bioenergetics of iron snow fueling life on Europa. Proc Natl Acad Sci U S A 2024; 121:e2316452121. [PMID: 38621125 PMCID: PMC11047109 DOI: 10.1073/pnas.2316452121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 03/11/2024] [Indexed: 04/17/2024] Open
Abstract
The main sources of redox gradients supporting high-productivity life in the Europan and other icy ocean world oceans were proposed to be photolytically derived oxidants, such as reactive oxygen species (ROS) from the icy shell, and reductants (Fe(II), S(-II), CH4, H2) from bottom waters reacting with a (ultra)mafic seafloor. Important roadblocks to maintaining life, however, are that the degree of ocean mixing to combine redox species is unknown, and ROS damage biomolecules. Here, we envisage a unique solution using an acid mine drainage (AMD)-filled pit lakes analog system for the Europan ocean, which previous models predicted to be acidic. We hypothesize that surface-generated ROS oxidize dissolved Fe(II) resulting in Fe(III) (hydr)oxide precipitates, that settle to the seafloor as "iron snow." The iron snow provides a respiratory substrate for anaerobic microorganisms ("breathing iron"), and limits harmful ROS exposure since they are now neutralized at the ice-water interface. Based on this scenario, we calculated Gibbs energies and maximal biomass productivities of various anaerobic metabolisms for a range of pH, temperatures, and H2 fluxes. Productivity by iron reducers was greater for most environmental conditions considered, whereas sulfate reducers and methanogens were more favored at high pH. Participation of Fe in the metabolic redox processes is largely neglected in most models of Europan biogeochemistry. Our model overcomes important conceptual roadblocks to life in icy ocean worlds and broadens the potential metabolic diversity, thus increasing total primary productivity, the diversity and volume of habitable environmental niches and, ultimately, the probability of biosignature detection.
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Affiliation(s)
- Nita Sahai
- School of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH44325
- Department of Geosciences, The University of Akron, Akron, OH44325
- Department of Biology, The University of Akron, Akron, OH44325
- Integrated Biosciences Program, The University of Akron, Akron, OH44325
| | - Doug LaRowe
- Department of Earth Sciences, University of Southern California, Los Angeles, CA90089
| | - John M. Senko
- Department of Geosciences, The University of Akron, Akron, OH44325
- Department of Biology, The University of Akron, Akron, OH44325
- Integrated Biosciences Program, The University of Akron, Akron, OH44325
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2
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Sieme D, Rezaei-Ghaleh N. Water dynamics in eutectic solutions of sodium chloride and magnesium sulfate: implications for life in Europa's subsurface ocean and ice shell. Phys Chem Chem Phys 2023; 26:105-115. [PMID: 38054803 DOI: 10.1039/d3cp03455k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
Liquid water is essential for life as we know it and the coupling between water and biomolecular dynamics is crucial for life processes. Jupiter's moon Europa is a good candidate for searching for extraterrestrial life in our outer solar system, mainly because a liquid water salty ocean in contact with a rocky seafloor underlies its ice shell. Little, however, is known about the chemical composition of the subglacial ocean of Europa or the brine pockets within its ice shell and their impacts on water dynamics. Here, we employ 1H, 17O, 23Na and 35Cl NMR spectroscopy, especially NMR spin relaxation and diffusion methods, and investigate the mobility of water molecules and ions in eutectic solutions of magnesium sulfate and sodium chloride, two salts ubiquitously present on the surface of Europa, over a range of temperatures and pressures pertinent to Europa's subglacial ocean. The NMR data demonstrate the more pronounced effect of magnesium sulfate compared with sodium chloride on the mobility of water molecules. Even at its much lower eutectic temperature, the sodium chloride solution retains a relatively large level of water mobility. Our results highlight the higher potential of a sodium chloride-rich than magnesium sulfate-rich Europa's ocean to accommodate life and support life origination within the eutectic melts of Europa's ice shell.
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Affiliation(s)
- Daniel Sieme
- Department of NMR-based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Am Faßberg 11, D-37077 Göttingen, Germany
| | - Nasrollah Rezaei-Ghaleh
- Heinrich Heine University (HHU) Düsseldorf, Faculty of Mathematics and Natural Sciences, Institute of Physical Biology, Universitätsstrasse 1, D-40225 Düsseldorf, Germany.
- Institute of Biological Information Processing, IBI-7: Structural Biochemistry, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, D-52428 Jülich, Germany
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3
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Hart R, Cardace D. Mineral Indicators of Geologically Recent Past Habitability on Mars. Life (Basel) 2023; 13:2349. [PMID: 38137950 PMCID: PMC10744562 DOI: 10.3390/life13122349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 11/25/2023] [Accepted: 12/05/2023] [Indexed: 12/24/2023] Open
Abstract
We provide new support for habitable microenvironments in the near-subsurface of Mars, hosted in Fe- and Mg-rich rock units, and present a list of minerals that can serve as indicators of specific water-rock reactions in recent geologic paleohabitats for follow-on study. We modeled, using a thermodynamic basis without selective phase suppression, the reactions of published Martian meteorites and Jezero Crater igneous rock compositions and reasonable planetary waters (saline, alkaline waters) using Geochemist's Workbench Ver. 12.0. Solid-phase inputs were meteorite compositions for ALH 77005, Nakhla, and Chassigny, and two rock units from the Mars 2020 Perseverance rover sites, Máaz and Séítah. Six plausible Martian groundwater types [NaClO4, Mg(ClO4)2, Ca(ClO4)2, Mg-Na2(ClO4)2, Ca-Na2(ClO4)2, Mg-Ca(ClO4)2] and a unique Mars soil-water analog solution (dilute saline solution) named "Rosy Red", related to the Phoenix Lander mission, were the aqueous-phase inputs. Geophysical conditions were tuned to near-subsurface Mars (100 °C or 373.15 K, associated with residual heat from a magmatic system, impact event, or a concentration of radionuclides, and 101.3 kPa, similar to <10 m depth). Mineral products were dominated by phyllosilicates such as serpentine-group minerals in most reaction paths, but differed in some important indicator minerals. Modeled products varied in physicochemical properties (pH, Eh, conductivity), major ion activities, and related gas fugacities, with different ecological implications. The microbial habitability of pore spaces in subsurface groundwater percolation systems was interrogated at equilibrium in a thermodynamic framework, based on Gibbs Free Energy Minimization. Models run with the Chassigny meteorite produced the overall highest H2 fugacity. Models reliant on the Rosy Red soil-water analog produced the highest sustained CH4 fugacity (maximum values observed for reactant ALH 77005). In general, Chassigny meteorite protoliths produced the best yield regarding Gibbs Free Energy, from an astrobiological perspective. Occurrences of serpentine and saponite across models are key: these minerals have been observed using CRISM spectral data, and their formation via serpentinization would be consistent with geologically recent-past H2 and CH4 production and sustained energy sources for microbial life. We list index minerals to be used as diagnostic for paleo water-rock models that could have supported geologically recent-past microbial activity, and suggest their application as criteria for future astrobiology study-site selections.
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Affiliation(s)
- Roger Hart
- Department of Physics and Engineering, Community College of Rhode Island, Lincoln, RI 02865, USA
- Department of Geosciences, University of Rhode Island, Kingston, RI 02881, USA;
| | - Dawn Cardace
- Department of Geosciences, University of Rhode Island, Kingston, RI 02881, USA;
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4
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Vance SD, Craft KL, Shock E, Schmidt BE, Lunine J, Hand KP, McKinnon WB, Spiers EM, Chivers C, Lawrence JD, Wolfenbarger N, Leonard EJ, Robinson KJ, Styczinski MJ, Persaud DM, Steinbrügge G, Zolotov MY, Quick LC, Scully JEC, Becker TM, Howell SM, Clark RN, Dombard AJ, Glein CR, Mousis O, Sephton MA, Castillo-Rogez J, Nimmo F, McEwen AS, Gudipati MS, Jun I, Jia X, Postberg F, Soderlund KM, Elder CM. Investigating Europa's Habitability with the Europa Clipper. SPACE SCIENCE REVIEWS 2023; 219:81. [PMID: 38046182 PMCID: PMC10687213 DOI: 10.1007/s11214-023-01025-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Accepted: 11/03/2023] [Indexed: 12/05/2023]
Abstract
The habitability of Europa is a property within a system, which is driven by a multitude of physical and chemical processes and is defined by many interdependent parameters, so that its full characterization requires collaborative investigation. To explore Europa as an integrated system to yield a complete picture of its habitability, the Europa Clipper mission has three primary science objectives: (1) characterize the ice shell and ocean including their heterogeneity, properties, and the nature of surface-ice-ocean exchange; (2) characterize Europa's composition including any non-ice materials on the surface and in the atmosphere, and any carbon-containing compounds; and (3) characterize Europa's geology including surface features and localities of high science interest. The mission will also address several cross-cutting science topics including the search for any current or recent activity in the form of thermal anomalies and plumes, performing geodetic and radiation measurements, and assessing high-resolution, co-located observations at select sites to provide reconnaissance for a potential future landed mission. Synthesizing the mission's science measurements, as well as incorporating remote observations by Earth-based observatories, the James Webb Space Telescope, and other space-based resources, to constrain Europa's habitability, is a complex task and is guided by the mission's Habitability Assessment Board (HAB).
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Affiliation(s)
- Steven D. Vance
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA USA
| | - Kathleen L. Craft
- Applied Physics Laboratory, Johns Hopkins University, Laurel, MD USA
| | - Everett Shock
- School of Earth & Space Exploration and School of Molecular Sciences, Arizona State University, Tempe, AZ USA
| | - Britney E. Schmidt
- Department of Astronomy and Department of Earth & Atmospheric Sciences, Cornell University, Ithaca, NY USA
| | - Jonathan Lunine
- Department of Astronomy and Department of Earth & Atmospheric Sciences, Cornell University, Ithaca, NY USA
| | - Kevin P. Hand
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA USA
| | - William B. McKinnon
- Department of Earth and Planetary Sciences and McDonnell Center for the Space Sciences, Washington University in St. Louis, Saint Louis, MO USA
| | - Elizabeth M. Spiers
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA USA
| | - Chase Chivers
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA USA
- Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Woods Hole, MA USA
| | - Justin D. Lawrence
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA USA
- Honeybee Robotics, Altadena, CA USA
| | - Natalie Wolfenbarger
- Institute for Geophysics, John A. and Katherine G. Jackson School of Geosciences, University of Texas at Austin, Austin, TX USA
| | - Erin J. Leonard
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA USA
| | | | | | - Divya M. Persaud
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA USA
| | - Gregor Steinbrügge
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA USA
| | - Mikhail Y. Zolotov
- School of Earth & Space Exploration and School of Molecular Sciences, Arizona State University, Tempe, AZ USA
| | | | | | | | - Samuel M. Howell
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA USA
| | | | - Andrew J. Dombard
- Dept. of Earth and Environmental Sciences, University of Illinois Chicago, Chicago, USA
| | | | - Olivier Mousis
- Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille), Marseille, France
| | - Mark A. Sephton
- Impacts and Astromaterials Research Centre, Department of Earth Science and Engineering, Imperial College London, London, United Kingdom
| | | | - Francis Nimmo
- Department of Earth and Planetary Sciences, University of California, Santa Cruz, CA USA
| | - Alfred S. McEwen
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ USA
| | - Murthy S. Gudipati
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA USA
| | - Insoo Jun
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA USA
| | - Xianzhe Jia
- Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI USA
| | - Frank Postberg
- Institut für Geologische Wissenschaften, Freie Universität Berlin, Berlin, Germany
| | - Krista M. Soderlund
- Institute for Geophysics, John A. and Katherine G. Jackson School of Geosciences, University of Texas at Austin, Austin, TX USA
| | - Catherine M. Elder
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA USA
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5
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Trumbo SK, Brown ME. The distribution of CO 2 on Europa indicates an internal source of carbon. Science 2023; 381:1308-1311. [PMID: 37733851 DOI: 10.1126/science.adg4155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 08/22/2023] [Indexed: 09/23/2023]
Abstract
Jupiter's moon Europa has a subsurface ocean, the chemistry of which is largely unknown. Carbon dioxide (CO2) has previously been detected on the surface of Europa, but it was not possible to determine whether it originated from subsurface ocean chemistry, was delivered by impacts, or was produced on the surface by radiation processing of impact-delivered material. We mapped the distribution of CO2 on Europa using observations obtained with the James Webb Space Telescope (JWST). We found a concentration of CO2 within Tara Regio, a recently resurfaced terrain. This indicates that the CO2 is derived from an internal carbon source. We propose that the CO2 formed in the internal ocean, although we cannot rule out formation on the surface through radiolytic conversion of ocean-derived organics or carbonates.
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Affiliation(s)
- Samantha K Trumbo
- Cornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca, NY 14853, USA
| | - Michael E Brown
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
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6
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Villanueva GL, Hammel HB, Milam SN, Faggi S, Kofman V, Roth L, Hand KP, Paganini L, Stansberry J, Spencer J, Protopapa S, Strazzulla G, Cruz-Mermy G, Glein CR, Cartwright R, Liuzzi G. Endogenous CO 2 ice mixture on the surface of Europa and no detection of plume activity. Science 2023; 381:1305-1308. [PMID: 37733858 DOI: 10.1126/science.adg4270] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 08/22/2023] [Indexed: 09/23/2023]
Abstract
Jupiter's moon Europa has a subsurface ocean beneath an icy crust. Conditions within the ocean are unknown, and it is unclear whether it is connected to the surface. We observed Europa with the James Webb Space Telescope (JWST) to search for active release of material by probing its surface and atmosphere. A search for plumes yielded no detection of water, carbon monoxide, methanol, ethane, or methane fluorescence emissions. Four spectral features of carbon dioxide (CO2) ice were detected; their spectral shapes and distribution across Europa's surface indicate that the CO2 is mixed with other compounds and concentrated in Tara Regio. The 13CO2 absorption is consistent with an isotopic ratio of 12C/13C = 83 ± 19. We interpret these observations as indicating that carbon is sourced from within Europa.
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Affiliation(s)
- G L Villanueva
- NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
| | - H B Hammel
- Association of Universities for Research in Astronomy, Washington, DC 20004, USA
| | - S N Milam
- NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
| | - S Faggi
- NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
- American University, Washington, DC 20016, USA
| | - V Kofman
- NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
- American University, Washington, DC 20016, USA
| | - L Roth
- Royal Institute of Technology, Stockholm 104 50, Sweden
| | - K P Hand
- Jet Propulsion Laboratory, Pasadena, CA 91109, USA
| | - L Paganini
- NASA Headquarters, Washington, DC 20546, USA
| | - J Stansberry
- Space Telescope Science Institute, Baltimore, MD 21218, USA
| | - J Spencer
- Southwest Research Institute, Boulder, CO 80302, USA
| | - S Protopapa
- Southwest Research Institute, Boulder, CO 80302, USA
| | - G Strazzulla
- Osservatorio Astrofisico di Catania, Istituto Nazionale di Astrofisica, 95123 Catania, Italy
| | - G Cruz-Mermy
- Universite Paris-Sarclay, 91190 Gif-sur-Yvette, France
| | - C R Glein
- Southwest Research Institute, San Antonio, TX 78238, USA
| | - R Cartwright
- Carl Sagan Center for Research, Search for Extraterrestrial Intelligence Institute, Mountain View, CA 94043, USA
| | - G Liuzzi
- Università degli Studi della Basilicata, 85100 Potenza, Italy
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7
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Trinh KT, Bierson CJ, O'Rourke JG. Slow evolution of Europa's interior: metamorphic ocean origin, delayed metallic core formation, and limited seafloor volcanism. SCIENCE ADVANCES 2023; 9:eadf3955. [PMID: 37327336 DOI: 10.1126/sciadv.adf3955] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 05/11/2023] [Indexed: 06/18/2023]
Abstract
Europa's ocean lies atop an interior made of metal and silicates. On the basis of gravity data from the Galileo mission, many argued that Europa's interior, like Earth, is differentiated into a metallic core and a mantle composed of anhydrous silicates. Some studies further assumed that Europa differentiated while (or soon after) it accreted, also like Earth. However, Europa probably formed at much colder temperatures, meaning that Europa plausibly ended accretion as a mixture containing water-ice and/or hydrated silicates. Here, we use numerical models to describe the thermal evolution of Europa's interior assuming low initial temperatures (~200 to 300 kelvin). We find that silicate dehydration can produce Europa's current ocean and icy shell. Rocks below the seafloor may remain cool and hydrated today. Europa's metallic core, if it exists, may have formed billions of years after accretion. Ultimately, we expect the chemistry of Europa's ocean to reflect protracted heating of the interior.
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Affiliation(s)
- Kevin T Trinh
- School of Earth and Space Exploration, Arizona State University, AZ 85287, USA
| | - Carver J Bierson
- School of Earth and Space Exploration, Arizona State University, AZ 85287, USA
| | - Joseph G O'Rourke
- School of Earth and Space Exploration, Arizona State University, AZ 85287, USA
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8
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Randolph-Flagg NG, Ely T, Som SM, Shock EL, German CR, Hoehler TM. Phosphate availability and implications for life on ocean worlds. Nat Commun 2023; 14:2388. [PMID: 37185347 PMCID: PMC10130162 DOI: 10.1038/s41467-023-37770-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 03/30/2023] [Indexed: 05/17/2023] Open
Abstract
Several moons in the outer solar system host liquid water oceans. A key next step in assessing the habitability of these ocean worlds is to determine whether life's elemental and energy requirements are also met. Phosphorus is required by all known life and is often limited to biological productivity in Earth's oceans. This raises the possibility that its availability may limit the abundance or productivity of Earth-like life on ocean worlds. To address this potential problem, here we calculate the equilibrium dissolved phosphate concentrations associated with the reaction of water and rocks-a key driver of ocean chemical evolution-across a broad range of compositional inputs and reaction conditions. Equilibrium dissolved phosphate concentrations range from 10-11 to 10-1 mol/kg across the full range of carbonaceous chondrite compositions and reaction conditions considered, but are generally > 10-5 mol/kg for most plausible scenarios. Relative to the phosphate requirements and uptake kinetics of microorganisms in Earth's oceans, such concentrations would be sufficient to support initially rapid cell growth and construction of global ocean cell populations larger than those observed in Earth's deep oceans.
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Affiliation(s)
- Noah G Randolph-Flagg
- Space Science and Astrobiology Division, NASA Ames Research Center, Moffett Field, Mountain View, CA, USA.
- NASA Postdoctoral Program, Universities Space Research Association, Columbia, MD, USA.
- Blue Marble Space Institute of Science, Seattle, WA, USA.
| | - Tucker Ely
- NASA Postdoctoral Program, Universities Space Research Association, Columbia, MD, USA
- Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, MN, USA
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
| | - Sanjoy M Som
- Space Science and Astrobiology Division, NASA Ames Research Center, Moffett Field, Mountain View, CA, USA
- Blue Marble Space Institute of Science, Seattle, WA, USA
| | - Everett L Shock
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
| | - Christopher R German
- Dept. Geology and Geophysics, Woods Hole Oceanographic Institution Woods Hole, Falmouth, MA, USA
| | - Tori M Hoehler
- Space Science and Astrobiology Division, NASA Ames Research Center, Moffett Field, Mountain View, CA, USA
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9
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Journaux B, Pakhomova A, Collings IE, Petitgirard S, Boffa Ballaran T, Brown JM, Vance SD, Chariton S, Prakapenka VB, Huang D, Ott J, Glazyrin K, Garbarino G, Comboni D, Hanfland M. On the identification of hyperhydrated sodium chloride hydrates, stable at icy moon conditions. Proc Natl Acad Sci U S A 2023; 120:e2217125120. [PMID: 36802438 PMCID: PMC9992769 DOI: 10.1073/pnas.2217125120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 01/20/2023] [Indexed: 02/23/2023] Open
Abstract
Sodium chloride is expected to be found on many of the surfaces of icy moons like Europa and Ganymede. However, spectral identification remains elusive as the known NaCl-bearing phases cannot match current observations, which require higher number of water of hydration. Working at relevant conditions for icy worlds, we report the characterization of three "hyperhydrated" sodium chloride (SC) hydrates, and refined two crystal structures [2NaCl·17H2O (SC8.5); NaCl·13H2O (SC13)]. We found that the dissociation of Na+ and Cl- ions within these crystal lattices allows for the high incorporation of water molecules and thus explain their hyperhydration. This finding suggests that a great diversity of hyperhydrated crystalline phases of common salts might be found at similar conditions. Thermodynamic constraints indicate that SC8.5 is stable at room pressure below 235 K, and it could be the most abundant NaCl hydrate on icy moon surfaces like Europa, Titan, Ganymede, Callisto, Enceladus, or Ceres. The finding of these hyperhydrated structures represents a major update to the H2O-NaCl phase diagram. These hyperhydrated structures provide an explanation for the mismatch between the remote observations of the surface of Europa and Ganymede and previously available data on NaCl solids. It also underlines the urgent need for mineralogical exploration and spectral data on hyperhydrates at relevant conditions to help future icy world exploration by space missions.
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Affiliation(s)
- Baptiste Journaux
- Department of Earth and Space Sciences, University of Washington, Seattle, WA98195
| | - Anna Pakhomova
- Deutsches Elektronen-Synchrotron, D-22607Hamburg, Germany
- European Synchrotron Radiation Facility, 38000Grenoble, France
| | - Ines E. Collings
- European Synchrotron Radiation Facility, 38000Grenoble, France
- Center for X-ray Analytics, Empa – Swiss Federal Laboratories for Materials Science and Technology, 8600Dübendorf, Switzerland
| | - Sylvain Petitgirard
- Institute of Geochemistry and Petrology, ETH Zürich, 8092Zürich, Switzerland
| | | | - J. Michael Brown
- Department of Earth and Space Sciences, University of Washington, Seattle, WA98195
| | - Steven D. Vance
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA91109
| | - Stella Chariton
- Center for Advanced Radiations Sources, University of Chicago, Chicago, IL60637
| | | | - Dongyang Huang
- Institute of Geochemistry and Petrology, ETH Zürich, 8092Zürich, Switzerland
| | - Jason Ott
- Department of Earth and Space Sciences, University of Washington, Seattle, WA98195
| | | | | | - Davide Comboni
- European Synchrotron Radiation Facility, 38000Grenoble, France
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10
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Castillo‐Rogez J, Weiss B, Beddingfield C, Biersteker J, Cartwright R, Goode A, Melwani Daswani M, Neveu M. Compositions and Interior Structures of the Large Moons of Uranus and Implications for Future Spacecraft Observations. JOURNAL OF GEOPHYSICAL RESEARCH. PLANETS 2023; 128:e2022JE007432. [PMID: 37034459 PMCID: PMC10078161 DOI: 10.1029/2022je007432] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 11/29/2022] [Accepted: 12/02/2022] [Indexed: 06/19/2023]
Abstract
The five large moons of Uranus are important targets for future spacecraft missions. To motivate and inform the exploration of these moons, we model their internal evolution, present-day physical structures, and geochemical and geophysical signatures that may be measured by spacecraft. We predict that if the moons preserved liquid until present, it is likely in the form of residual oceans less than 30 km thick in Ariel, Umbriel, and less than 50 km in Titania, and Oberon. The preservation of liquid strongly depends on material properties and, potentially, on dynamical circumstances that are presently unknown. Miranda is unlikely to host liquid at present unless it experienced tidal heating a few tens of million years ago. We find that since the thin residual layers may be hypersaline, their induced magnetic fields could be detectable by future spacecraft-based magnetometers. However, if the ocean is maintained primarily by ammonia, and thus well below the water freezing point, then its electrical conductivity may be too small to be detectable by spacecraft. Lastly, our calculated tidal Love number (k 2) and dissipation factor (Q) are consistent with the Q/k 2 values previously inferred from dynamical evolution models. In particular, we find that the low Q/k 2 estimated for Titania supports the hypothesis that Titania currently holds an ocean.
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Affiliation(s)
| | - Benjamin Weiss
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of Technology (MIT)CambridgeMAUSA
| | - Chloe Beddingfield
- SETI InstituteMountain ViewCAUSA
- NASA Ames Research CenterMountain ViewCAUSA
| | - John Biersteker
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of Technology (MIT)CambridgeMAUSA
| | | | - Allison Goode
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of Technology (MIT)CambridgeMAUSA
| | | | - Marc Neveu
- University of MarylandCollege ParkMDUSA
- NASA Goddard Space Flight CenterGreenbeltMDUSA
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11
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Morrison AA, Whittington AG, Mitchell KL. A Reevaluation of Cryolava Flow Evolution: Assumptions, Physical Properties, and Conceptualization. JOURNAL OF GEOPHYSICAL RESEARCH. PLANETS 2023; 128:e2022JE007383. [PMID: 37034461 PMCID: PMC10078481 DOI: 10.1029/2022je007383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 12/05/2022] [Accepted: 12/06/2022] [Indexed: 06/19/2023]
Abstract
Cryovolcanism has been invoked to explain numerous features observed on icy bodies. Many of these features show similar morphologies to volcanic features observed on Earth suggesting similar physics involved in their formation. Cryovolcanism lies at the intersection of volcanology and hydrology but as such, no one model from either discipline satisfactorily represents cryolava flow emplacement. We produced a new model for cryolava flow evolution that draws from both disciplines to track the physical, chemical, and thermal states of a hypothetical H2O-NaCl flow on a Europa-like body as it evolves away from the vent. This model is currently restricted to compositions on the water-rich side of this chemical system and only predicts emplacement up to the turbulent to laminar transition. Modeling the laminar regime and a broader compositional space will be dealt with separately. Concentrations between 5 and 23 wt% (H2O-NaCl eutectic) and initial flow thicknesses of 0.1, 1, 10, and 100 m were set as initial conditions. Model results suggest that flow may reach 40-60 vol% solids before transitioning to laminar flow. The thermal budget for these flows is dominated by the heat loss from vaporization in the low-pressure environment. This model produces length to thickness aspect ratios, for the given compositions, that are broadly consistent with candidate cryovolcanic features on Ceres and Titan. These first-order comparisons are not ideal and suggest the need for future modeling of cryovolcanic features in at least two dimensions.
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Affiliation(s)
- Aaron A. Morrison
- Department of Geological SciencesThe University of Texas at San AntonioSan AntonioTXUSA
| | - Alan G. Whittington
- Department of Geological SciencesThe University of Texas at San AntonioSan AntonioTXUSA
| | - Karl L. Mitchell
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
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Wolfenbarger NS, Buffo JJ, Soderlund KM, Blankenship DD. Ice Shell Structure and Composition of Ocean Worlds: Insights from Accreted Ice on Earth. ASTROBIOLOGY 2022; 22:937-961. [PMID: 35787145 DOI: 10.1089/ast.2021.0044] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Accreted ice retains and preserves traces of the ocean from which it formed. In this work, we study two classes of accreted ice found on Earth-frazil ice, which forms through crystallization within a supercooled water column, and congelation ice, which forms through directional freezing at an existing interface-and discuss where each might be found in the ice shells of ocean worlds. We focus our study on terrestrial ice formed in low temperature gradient environments (e.g., beneath ice shelves), consistent with conditions expected at the ice-ocean interfaces of Europa and Enceladus, and we highlight the juxtaposition of compositional trends in relation to ice formed in higher temperature gradient environments (e.g., at the ocean surface). Observations from Antarctic sub-ice-shelf congelation ice and marine ice show that the purity of frazil ice can be nearly two orders of magnitude higher than congelation ice formed in the same low temperature gradient environment (∼0.1% vs. ∼10% of the ocean salinity). In addition, where congelation ice can maintain a planar ice-water interface on a microstructural scale, the efficiency of salt rejection is enhanced (∼1% of the ocean salinity) and lattice soluble impurities such as chloride are preferentially incorporated. We conclude that an ice shell that forms by gradual thickening as its interior cools would be composed of congelation ice, whereas frazil ice will accumulate where the ice shell thins on local (rifts and basal fractures) or regional (latitudinal gradients) scales through the operation of an "ice pump."
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Affiliation(s)
| | - Jacob J Buffo
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, USA
| | - Krista M Soderlund
- Institute for Geophysics, University of Texas at Austin, Austin, Texas, USA
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