1
|
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.
Collapse
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
| |
Collapse
|
2
|
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.
Collapse
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
| |
Collapse
|
3
|
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).
Collapse
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
| |
Collapse
|
4
|
Boxberg MS, Chen Q, Plesa AC, Kowalski J. Ice Transit and Performance Analysis for Cryorobotic Subglacial Access Missions on Earth and Europa. ASTROBIOLOGY 2023; 23:1135-1152. [PMID: 36576448 DOI: 10.1089/ast.2021.0071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Ice-covered ocean worlds, such as the Jovian moon Europa, are some of the prime targets for planetary exploration due to their high astrobiological potential. While upcoming space exploration missions, such as the Europa Clipper and JUICE missions, will give us further insight into the local cryoenvironment, any conclusive life detection investigation requires the capability to penetrate and transit the icy shell and access the subglacial ocean directly. Developing robust, autonomous cryorobotic technology for such a mission constitutes an extremely demanding multistakeholder challenge and requires a concentrated interdisciplinary effort between engineers, geoscientists, and astrobiologists. An important tool with which to foster cross-disciplinary work at an early stage of mission preparation is the virtual testbed. In this article, we report on recent progress in the development of an ice transit and performance model for later integration in such a virtual testbed. We introduce a trajectory model that, for the first time, allows for the evaluation of mission-critical parameters, such as transit time and average/overall power supply. Our workflow is applied to selected, existing cryobot designs while taking into consideration different terrestrial, as well as extraterrestrial, deployment scenarios. Specific analyses presented in this study show the tradeoff minimum transit time and maximum efficiency of a cryobot and allow for quantification of different sources of uncertainty to cryobot's trajectory models.
Collapse
Affiliation(s)
- Marc S Boxberg
- Chair of Methods for Model-based Development in Computational Engineering, RWTH Aachen University, Aachen, Germany
- Computational Geoscience, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Qian Chen
- Chair of Methods for Model-based Development in Computational Engineering, RWTH Aachen University, Aachen, Germany
| | - Ana-Catalina Plesa
- Institute of Planetary Research, German Aerospace Center (DLR), Berlin, Germany
| | - Julia Kowalski
- Chair of Methods for Model-based Development in Computational Engineering, RWTH Aachen University, Aachen, Germany
- Computational Geoscience, Georg-August-Universität Göttingen, Göttingen, Germany
| |
Collapse
|
5
|
Roberts JH, McKinnon WB, Elder CM, Tobie G, Biersteker JB, Young D, Park RS, Steinbrügge G, Nimmo F, Howell SM, Castillo-Rogez JC, Cable ML, Abrahams JN, Bland MT, Chivers C, Cochrane CJ, Dombard AJ, Ernst C, Genova A, Gerekos C, Glein C, Harris CD, Hay HCFC, Hayne PO, Hedman M, Hussmann H, Jia X, Khurana K, Kiefer WS, Kirk R, Kivelson M, Lawrence J, Leonard EJ, Lunine JI, Mazarico E, McCord TB, McEwen A, Paty C, Quick LC, Raymond CA, Retherford KD, Roth L, Rymer A, Saur J, Scanlan K, Schroeder DM, Senske DA, Shao W, Soderlund K, Spiers E, Styczinski MJ, Tortora P, Vance SD, Villarreal MN, Weiss BP, Westlake JH, Withers P, Wolfenbarger N, Buratti B, Korth H, Pappalardo RT. Exploring the Interior of Europa with the Europa Clipper. SPACE SCIENCE REVIEWS 2023; 219:46. [PMID: 37636325 PMCID: PMC10457249 DOI: 10.1007/s11214-023-00990-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Accepted: 07/20/2023] [Indexed: 08/29/2023]
Abstract
The Galileo mission to Jupiter revealed that Europa is an ocean world. The Galileo magnetometer experiment in particular provided strong evidence for a salty subsurface ocean beneath the ice shell, likely in contact with the rocky core. Within the ice shell and ocean, a number of tectonic and geodynamic processes may operate today or have operated at some point in the past, including solid ice convection, diapirism, subsumption, and interstitial lake formation. The science objectives of the Europa Clipper mission include the characterization of Europa's interior; confirmation of the presence of a subsurface ocean; identification of constraints on the depth to this ocean, and on its salinity and thickness; and determination of processes of material exchange between the surface, ice shell, and ocean. Three broad categories of investigation are planned to interrogate different aspects of the subsurface structure and properties of the ice shell and ocean: magnetic induction, subsurface radar sounding, and tidal deformation. These investigations are supplemented by several auxiliary measurements. Alone, each of these investigations will reveal unique information. Together, the synergy between these investigations will expose the secrets of the Europan interior in unprecedented detail, an essential step in evaluating the habitability of this ocean world.
Collapse
Affiliation(s)
| | | | - Catherine M Elder
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | | | | | | | - Ryan S Park
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Gregor Steinbrügge
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Francis Nimmo
- University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Samuel M Howell
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | | | - Morgan L Cable
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | | | | | | | - Corey J Cochrane
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | | | - Carolyn Ernst
- Johns Hopkins Applied Physics Laboratory, Laurel, MD, USA
| | | | | | | | | | - Hamish C F C Hay
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Paul O Hayne
- University of Colorado Boulder, Boulder, CO, USA
| | | | - Hauke Hussmann
- German Aerospace Center Institute of Planetary Research, Berlin, Germany
| | | | | | - Walter S Kiefer
- Lunar and Planetary Institute, University Space Research Association, Houston, TX, USA
| | | | | | | | - Erin J Leonard
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | | | | | | | | | | | | | - Carol A Raymond
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Kurt D Retherford
- Sapienza University of Rome, Rome, Italy
- University of Texas at San Antonio, San Antonio, TX, USA
| | - Lorenz Roth
- KTH Royal Institute of Technology, Stockholm, Sweden
| | - Abigail Rymer
- Johns Hopkins Applied Physics Laboratory, Laurel, MD, USA
| | | | | | | | - David A Senske
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Wencheng Shao
- University of California, Santa Cruz, Santa Cruz, CA, USA
| | | | | | - Marshall J Styczinski
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
- University of Washington, Seattle, WA, USA
| | - Paolo Tortora
- Alma Mater Studiorum - Università di Bologna, Bologna, Italy
| | - Steven D Vance
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | | | | | | | | | | | - Bonnie Buratti
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Haje Korth
- Johns Hopkins Applied Physics Laboratory, Laurel, MD, USA
| | - Robert T Pappalardo
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| |
Collapse
|
6
|
Boulesteix D, Buch A, Samson J, Millan M, Jomaa J, Coscia D, Moulay V, McIntosh O, Freissinet C, Stern JC, Szopa C. Influence of pH and salts on DMF-DMA derivatization for future Space Applications. Anal Chim Acta 2023; 1266:341270. [PMID: 37244655 DOI: 10.1016/j.aca.2023.341270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/24/2023] [Accepted: 04/23/2023] [Indexed: 05/29/2023]
Abstract
For gas chromatography - mass spectrometry (GC-MS) analyses performed in situ, pH and salts (e.g., chlorides, sulfates) may enhance or inhibit the detection of targeted molecules of interest for astrobiology (e.g. amino acids, fatty acids, nucleobases). Obviously, salts influence the ionic strength of the solutions, the pH value, and the salting effect. But the presence of salts may also produce complexes or mask ions in the sample (masking effect on hydroxide ion, ammonia, etc.). For future space missions, wet chemistry will be conducted before GC-MS analyses to detect the full organic content of a sample. The defined organic targets for space GC-MS instrument requirements are generally strongly polar or refractory organic compounds, such as amino acids playing a role in the protein production and metabolism regulations for life on Earth, nucleobases essential for DNA and RNA formation and mutation, and fatty acids that composed most of the eukaryote and prokaryote membranes on Earth and resist to environmental stress long enough to still be observed on Mars or ocean worlds in geological well-preserved records. The wet-chemistry chemical treatment consists of reacting an organic reagent with the sample to extract and volatilize polar or refractory organic molecules (i.e. dimethylformamide dimethyl acetal (DMF-DMA) in this study). DMF-DMA derivatizes functional groups with labile H in organics, without modifying their chiral conformation. The influence of pH and salt concentration of extraterrestrial materials on the DMF-DMA derivatization remains understudied. In this research, we studied the influence of different salts and pHs on the derivatization of organic molecules of astrobiological interest with DMF-DMA, such as amino acids, carboxylic acids, and nucleobases. Results show that salts and pH influence the derivatization yield, and that their effect depend on the nature of the organics and the salts studied. Second, monovalent salts lead to a higher or similar organic recovery compared to divalent salts regardless of pH below 8. However, a pH above 8 inhibits the DMF-DMA derivatization influencing the carboxylic acid function to become an anionic group without labile H. Overall, considering the negative effect of the salts on the detection of organic molecules, future space missions may have to consider a desalting step prior to derivatization and GC-MS analyses.
Collapse
Affiliation(s)
- D Boulesteix
- Laboratoire Génie des Procédés et Matériaux, CentraleSupélec, University Paris-Saclay, 8-10 Rue Joliot-Curie, 91190, Gif-sur-Yvette, France.
| | - A Buch
- Laboratoire Génie des Procédés et Matériaux, CentraleSupélec, University Paris-Saclay, 8-10 Rue Joliot-Curie, 91190, Gif-sur-Yvette, France.
| | - J Samson
- Laboratoire Génie des Procédés et Matériaux, CentraleSupélec, University Paris-Saclay, 8-10 Rue Joliot-Curie, 91190, Gif-sur-Yvette, France
| | - M Millan
- LATMOS/IPSL, UVSQ University Paris-Saclay, Sorbonne University, CNRS, 11 Bd d'Alembert, 78280, Guyancourt, France
| | - J Jomaa
- Planetary Environments Laboratory (Code 699), NASA Goddard Space Flight Center, Greenbelt, MD, 20771, USA; School of Medicine, Wayne State University, 42 W. Warren Ave, Detroit, MI, 48202, USA
| | - D Coscia
- LATMOS/IPSL, UVSQ University Paris-Saclay, Sorbonne University, CNRS, 11 Bd d'Alembert, 78280, Guyancourt, France
| | - V Moulay
- LATMOS/IPSL, UVSQ University Paris-Saclay, Sorbonne University, CNRS, 11 Bd d'Alembert, 78280, Guyancourt, France
| | - O McIntosh
- LATMOS/IPSL, UVSQ University Paris-Saclay, Sorbonne University, CNRS, 11 Bd d'Alembert, 78280, Guyancourt, France
| | - C Freissinet
- LATMOS/IPSL, UVSQ University Paris-Saclay, Sorbonne University, CNRS, 11 Bd d'Alembert, 78280, Guyancourt, France
| | - J C Stern
- Space Science Exploration Division (Code 690), NASA, Goddard Space Flight Center, Greenbelt, MD, 20771, USA
| | - C Szopa
- LATMOS/IPSL, UVSQ University Paris-Saclay, Sorbonne University, CNRS, 11 Bd d'Alembert, 78280, Guyancourt, France
| |
Collapse
|
7
|
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.
Collapse
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
| |
Collapse
|
8
|
Thompson SP, Kennedy H, Butler BM, Day SJ, Safi E, Evans A. Laboratory exploration of mineral precipitates from Europa's subsurface ocean. J Appl Crystallogr 2021; 54:1455-1479. [PMID: 34667451 PMCID: PMC8493616 DOI: 10.1107/s1600576721008554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 08/17/2021] [Indexed: 11/10/2022] Open
Abstract
The precipitation of hydrated phases from a chondrite-like Na-Mg-Ca-SO4-Cl solution is studied using in situ synchrotron X-ray powder diffraction, under rapid- (360 K h-1, T = 250-80 K, t = 3 h) and ultra-slow-freezing (0.3 K day-1, T = 273-245 K, t = 242 days) conditions. The precipitation sequence under slow cooling initially follows the predictions of equilibrium thermodynamics models. However, after ∼50 days at 245 K, the formation of the highly hydrated sulfate phase Na2Mg(SO4)2·16H2O, a relatively recent discovery in the Na2Mg(SO4)2-H2O system, was observed. Rapid freezing, on the other hand, produced an assemblage of multiple phases which formed within a very short timescale (≤4 min, ΔT = 2 K) and, although remaining present throughout, varied in their relative proportions with decreasing temperature. Mirabilite and meridianiite were the major phases, with pentahydrite, epsomite, hydrohalite, gypsum, blödite, konyaite and loweite also observed. Na2Mg(SO4)2·16H2O was again found to be present and increased in proportion relative to other phases as the temperature decreased. The results are discussed in relation to possible implications for life on Europa and application to other icy ocean worlds.
Collapse
Affiliation(s)
- Stephen P. Thompson
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Hilary Kennedy
- School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey LL59 5AB, United Kingdom
| | - Benjamin M. Butler
- Environmental and Biochemical Sciences, The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, United Kingdom
| | - Sarah J. Day
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Emmal Safi
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
- Astrophysics Group, Lennard-Jones Laboratories, Keele University, Keele, Staffordshire ST5 5BG, United Kingdom
| | - Aneurin Evans
- Astrophysics Group, Lennard-Jones Laboratories, Keele University, Keele, Staffordshire ST5 5BG, United Kingdom
| |
Collapse
|
9
|
Melwani Daswani M, Vance SD, Mayne MJ, Glein CR. A Metamorphic Origin for Europa's Ocean. GEOPHYSICAL RESEARCH LETTERS 2021; 48:e2021GL094143. [PMID: 35865189 PMCID: PMC9286408 DOI: 10.1029/2021gl094143] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 07/26/2021] [Accepted: 08/04/2021] [Indexed: 05/28/2023]
Abstract
Europa likely contains an iron-rich metal core. For it to have formed, temperatures within Europa reached ≳ 1250 K. Going up to that temperature, accreted chondritic minerals - for example, carbonates and phyllosilicates - would partially devolatilize. Here, we compute the amounts and compositions of exsolved volatiles. We find that volatiles released from the interior would have carried solutes, redox-sensitive species, and could have generated a carbonic ocean in excess of Europa's present-day hydrosphere, and potentially an early CO 2 atmosphere. No late delivery of cometary water was necessary. Contrasting with prior work, CO 2 could be the most abundant solute in the ocean, followed by Ca 2 + , SO 4 2 - , and HCO 3 - . However, gypsum precipitation going from the seafloor to the ice shell decreases the dissolved S/Cl ratio, such that Cl > S at the shallowest depths, consistent with recently inferred endogenous chlorides at Europa's surface. Gypsum would form a 3-10 km thick sedimentary layer at the seafloor.
Collapse
Affiliation(s)
| | - Steven D. Vance
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - Matthew J. Mayne
- Department of Earth SciencesStellenbosch UniversityStellenboschSouth Africa
| | - Christopher R. Glein
- Space Science and Engineering DivisionSouthwest Research InstituteSan AntonioTXUSA
| |
Collapse
|
10
|
Sandford MW, Misra AK, Acosta-Maeda TE, Sharma SK, Porter JN, Egan MJ, Abedin MN. Detecting Minerals and Organics Relevant to Planetary Exploration Using a Compact Portable Remote Raman System at 122 Meters. APPLIED SPECTROSCOPY 2021; 75:299-306. [PMID: 32613858 DOI: 10.1177/0003702820943669] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Raman spectroscopy is a technique that can detect and characterize a range of molecular compounds such as water, water ice, water-bearing minerals, and organics of particular interest to planetary science. The detection and characterization of these molecular compounds, which are indications of habitability on planetary bodies, have become an important goal for planetary exploration missions spanning the solar system. Using a compact portable remote Raman system consisting of a 532 nm neodymium-doped yttrium aluminum garnet- (Nd:YAG-) pulsed laser, a 3-in. (7.62 cm) diameter mirror lens and a compact spectrograph with a miniature intensified charge coupled device (mini-ICCD), we were able to detect water (H2O), water ice (H2O-ice), CO2-ice, hydrous minerals, organics, nitrates, and an amino acid from a remote distance of 122 m in natural lighting conditions. To the best of our knowledge, this is the longest remote Raman detection using a compact system. The development of this uniquely compact portable remote Raman system is applicable to a range of solar system exploration missions including stationary landers for ocean worlds and lunar exploration, as they provide unambiguous detection of compounds indicative of life as well as resources necessary for further human exploration.
Collapse
Affiliation(s)
- Macey W Sandford
- Hawaii Institute of Geophysics and Planetology, University of Hawai'i at Mānoa, Honolulu, HI, USA
| | - Anupam K Misra
- Hawaii Institute of Geophysics and Planetology, University of Hawai'i at Mānoa, Honolulu, HI, USA
| | - Tayro E Acosta-Maeda
- Hawaii Institute of Geophysics and Planetology, University of Hawai'i at Mānoa, Honolulu, HI, USA
| | - Shiv K Sharma
- Hawaii Institute of Geophysics and Planetology, University of Hawai'i at Mānoa, Honolulu, HI, USA
| | - John N Porter
- Hawaii Institute of Geophysics and Planetology, University of Hawai'i at Mānoa, Honolulu, HI, USA
| | - Miles J Egan
- Hawaii Institute of Geophysics and Planetology, University of Hawai'i at Mānoa, Honolulu, HI, USA
| | | |
Collapse
|
11
|
Cockell CS, McLean CM, Perera L, Aka S, Stevens A, Dickinson AW. Growth of Non-Halophilic Bacteria in the Sodium-Magnesium-Sulfate-Chloride Ion System: Unravelling the Complexities of Ion Interactions in Terrestrial and Extraterrestrial Aqueous Environments. ASTROBIOLOGY 2020; 20:944-955. [PMID: 32434375 DOI: 10.1089/ast.2019.2092] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Motivated by an interest in understanding the habitability of aqueous environments on Earth and in extraterrestrial settings, this study investigated the influence of ions in an artificial sodium-magnesium-sulfate-chloride ion system on the growth parameters (lag phase, growth rate, and final cell concentration) of bacteria. These four ions, in different combinations, are key components of many aqueous environments on Earth and elsewhere. We investigated non-halophilic bacteria deliberately to remove the bias of prior adaptations to high concentrations of selected ions so that we could compare the effects of different ions. We tested the hypothesis that water activity determined the growth parameters independent of the ion types. Neither water activity or ionic strength alone could predict growth. However, when ionic strengths were matched, many differences in growth parameters could be explained by the water activity. We suggest that species-specific effects (caused by differences in biochemical and physiological influences), the role of individual ions in cellular processes, and potentially the chaotropicity and kosmotropicity of solutions influenced the growth. Our data show that although extreme combinations of these ions allow for general predictions on the habitability of extraterrestrial aqueous environments, a complex interplay of ionic effects influences the growth and thus the adaptations required for given ion combinations. The data also show that an accurate quantification of the habitability of ocean worlds, such as Europa and Enceladus, can only be made when samples are obtained from these water bodies and the ion combinations are determined.
Collapse
Affiliation(s)
- Charles S Cockell
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| | - Claire-Marie McLean
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| | - Liam Perera
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| | - Salomé Aka
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| | - Adam Stevens
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| | - Andrew W Dickinson
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| |
Collapse
|
12
|
Castillo-Rogez JC, Neveu M, Scully JEC, House CH, Quick LC, Bouquet A, Miller K, Bland M, De Sanctis MC, Ermakov A, Hendrix AR, Prettyman TH, Raymond CA, Russell CT, Sherwood BE, Young E. Ceres: Astrobiological Target and Possible Ocean World. ASTROBIOLOGY 2020; 20:269-291. [PMID: 31904989 DOI: 10.1089/ast.2018.1999] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Ceres, the most water-rich body in the inner solar system after Earth, has recently been recognized to have astrobiological importance. Chemical and physical measurements obtained by the Dawn mission enabled the quantification of key parameters, which helped to constrain the habitability of the inner solar system's only dwarf planet. The surface chemistry and internal structure of Ceres testify to a protracted history of reactions between liquid water, rock, and likely organic compounds. We review the clues on chemical composition, temperature, and prospects for long-term occurrence of liquid and chemical gradients. Comparisons with giant planet satellites indicate similarities both from a chemical evolution standpoint and in the physical mechanisms driving Ceres' internal evolution.
Collapse
Affiliation(s)
| | - Marc Neveu
- Sciences and Exploration Directorate, NASA Goddard Space Flight Center, Greenbelt, Maryland
- University of Maryland College Park, Greenbelt, Maryland
| | - Jennifer E C Scully
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
| | - Christopher H House
- Department of Geosciences,Penn State Astrobiology Research Center, The Pennsylvania State University, University Park, Pennsylvania
| | - Lynnae C Quick
- Sciences and Exploration Directorate, NASA Goddard Space Flight Center, Greenbelt, Maryland
| | - Alexis Bouquet
- LAM (Laboratoire d'Astrophysique de Marseille), Aix Marseille Université, CNRS, UMR 7326, Marseille, France
| | - Kelly Miller
- Southwest Research Institute, San Antonio, Texas
| | | | | | - Anton Ermakov
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
| | | | | | - Carol A Raymond
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
| | - Christopher T Russell
- Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, California
| | | | - Edward Young
- Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, California
| |
Collapse
|
13
|
|
14
|
|
15
|
Acosta-Maeda TE, Misra AK, Muzangwa LG, Berlanga G, Muchow D, Porter J, Sharma SK. Remote Raman measurements of minerals, organics, and inorganics at 430 m range. APPLIED OPTICS 2016; 55:10283-10289. [PMID: 28059247 DOI: 10.1364/ao.55.010283] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Raman spectroscopy is a characterization technique that is able to analyze and detect water or water-bearing minerals, minerals, and organic materials that are of special interest for planetary science. Using a portable pulsed remote Raman system with a commercial 8 in. (203.2 mm) telescope, a frequency doubled Nd-YAG-pulsed laser, and a spectrometer equipped with an intensified CCD camera, we acquired good quality Raman spectra of various materials from a 430 m standoff distance during daylight with detection times of 1-10 s, in a realistic context in which both the exciting source and the detector are part of the same measurement system. Remote Raman spectra at this distance provided unambiguous detection of compounds such as water and water ice, dry ice, sulfur, sulfates, various minerals and organics, and atmospheric gases. This research work demonstrates significant improvement in the remote Raman technique as well as its suitability for solar system exploration.
Collapse
|
16
|
Cockell CS, Bush T, Bryce C, Direito S, Fox-Powell M, Harrison JP, Lammer H, Landenmark H, Martin-Torres J, Nicholson N, Noack L, O'Malley-James J, Payler SJ, Rushby A, Samuels T, Schwendner P, Wadsworth J, Zorzano MP. Habitability: A Review. ASTROBIOLOGY 2016; 16:89-117. [PMID: 26741054 DOI: 10.1089/ast.2015.1295] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Habitability is a widely used word in the geoscience, planetary science, and astrobiology literature, but what does it mean? In this review on habitability, we define it as the ability of an environment to support the activity of at least one known organism. We adopt a binary definition of "habitability" and a "habitable environment." An environment either can or cannot sustain a given organism. However, environments such as entire planets might be capable of supporting more or less species diversity or biomass compared with that of Earth. A clarity in understanding habitability can be obtained by defining instantaneous habitability as the conditions at any given time in a given environment required to sustain the activity of at least one known organism, and continuous planetary habitability as the capacity of a planetary body to sustain habitable conditions on some areas of its surface or within its interior over geological timescales. We also distinguish between surface liquid water worlds (such as Earth) that can sustain liquid water on their surfaces and interior liquid water worlds, such as icy moons and terrestrial-type rocky planets with liquid water only in their interiors. This distinction is important since, while the former can potentially sustain habitable conditions for oxygenic photosynthesis that leads to the rise of atmospheric oxygen and potentially complex multicellularity and intelligence over geological timescales, the latter are unlikely to. Habitable environments do not need to contain life. Although the decoupling of habitability and the presence of life may be rare on Earth, it may be important for understanding the habitability of other planetary bodies.
Collapse
Affiliation(s)
- C S Cockell
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - T Bush
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - C Bryce
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - S Direito
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - M Fox-Powell
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - J P Harrison
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - H Lammer
- 2 Austrian Academy of Sciences, Space Research Institute , Graz, Austria
| | - H Landenmark
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - J Martin-Torres
- 3 Division of Space Technology, Department of Computer Science, Electrical and Space Engineering, Luleå University of Technology , Kiruna, Sweden; and Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR), Armilla, Granada, Spain
| | - N Nicholson
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - L Noack
- 4 Department of Reference Systems and Planetology, Royal Observatory of Belgium , Brussels, Belgium
| | - J O'Malley-James
- 5 School of Physics and Astronomy, University of St Andrews , St Andrews, UK; now at the Carl Sagan Institute, Cornell University, Ithaca, NY, USA
| | - S J Payler
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - A Rushby
- 6 Centre for Ocean and Atmospheric Science (COAS), School of Environmental Sciences, University of East Anglia , Norwich, UK
| | - T Samuels
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - P Schwendner
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - J Wadsworth
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - M P Zorzano
- 3 Division of Space Technology, Department of Computer Science, Electrical and Space Engineering, Luleå University of Technology , Kiruna, Sweden; and Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR), Armilla, Granada, Spain
- 7 Centro de Astrobiología (CSIC-INTA) , Torrejón de Ardoz, Madrid, Spain
| |
Collapse
|
17
|
Pappalardo RT, Vance S, Bagenal F, Bills BG, Blaney DL, Blankenship DD, Brinckerhoff WB, Connerney JEP, Hand KP, Hoehler TM, Leisner JS, Kurth WS, McGrath MA, Mellon MT, Moore JM, Patterson GW, Prockter LM, Senske DA, Schmidt BE, Shock EL, Smith DE, Soderlund KM. Science potential from a Europa lander. ASTROBIOLOGY 2013; 13:740-773. [PMID: 23924246 DOI: 10.1089/ast.2013.1003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The prospect of a future soft landing on the surface of Europa is enticing, as it would create science opportunities that could not be achieved through flyby or orbital remote sensing, with direct relevance to Europa's potential habitability. Here, we summarize the science of a Europa lander concept, as developed by our NASA-commissioned Science Definition Team. The science concept concentrates on observations that can best be achieved by in situ examination of Europa from its surface. We discuss the suggested science objectives and investigations for a Europa lander mission, along with a model planning payload of instruments that could address these objectives. The highest priority is active sampling of Europa's non-ice material from at least two different depths (0.5-2 cm and 5-10 cm) to understand its detailed composition and chemistry and the specific nature of salts, any organic materials, and other contaminants. A secondary focus is geophysical prospecting of Europa, through seismology and magnetometry, to probe the satellite's ice shell and ocean. Finally, the surface geology can be characterized in situ at a human scale. A Europa lander could take advantage of the complex radiation environment of the satellite, landing where modeling suggests that radiation is about an order of magnitude less intense than in other regions. However, to choose a landing site that is safe and would yield the maximum science return, thorough reconnaissance of Europa would be required prior to selecting a scientifically optimized landing site.
Collapse
Affiliation(s)
- R T Pappalardo
- Planetary Sciences Section, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Pasek MA, Greenberg R. Acidification of Europa's subsurface ocean as a consequence of oxidant delivery. ASTROBIOLOGY 2012; 12:151-159. [PMID: 22283235 DOI: 10.1089/ast.2011.0666] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Oxidants are formed at the surface of Europa and may be delivered to the subsurface ocean, possibly in great quantities. Whether these substances would be available for biological metabolism is uncertain, because they may react with sulfides and other compounds to generate sulfuric and other acids. If this process has been active on Europa for much of its age, then not only would it rob the ocean of life-supporting oxidants but the subsurface ocean could have a pH of ~2.6, which is so acidic as to present an environmental challenge for life, unless organisms consume or sequester the oxidants fast enough to ameliorate the acidification.
Collapse
Affiliation(s)
- Matthew A Pasek
- Department of Geology, University of South Florida, Tampa, Florida 33620, USA.
| | | |
Collapse
|
19
|
Vance S, Harnmeijer J, Kimura J, Hussmann H, Demartin B, Brown JM. Hydrothermal systems in small ocean planets. ASTROBIOLOGY 2007; 7:987-1005. [PMID: 18163874 DOI: 10.1089/ast.2007.0075] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We examine means for driving hydrothermal activity in extraterrestrial oceans on planets and satellites of less than one Earth mass, with implications for sustaining a low level of biological activity over geological timescales. Assuming ocean planets have olivine-dominated lithospheres, a model for cooling-induced thermal cracking shows how variation in planet size and internal thermal energy may drive variation in the dominant type of hydrothermal system-for example, high or low temperature system or chemically driven system. As radiogenic heating diminishes over time, progressive exposure of new rock continues to the current epoch. Where fluid-rock interactions propagate slowly into a deep brittle layer, thermal energy from serpentinization may be the primary cause of hydrothermal activity in small ocean planets. We show that the time-varying hydrostatic head of a tidally forced ice shell may drive hydrothermal fluid flow through the seafloor, which can generate moderate but potentially important heat through viscous interaction with the matrix of porous seafloor rock. Considering all presently known potential ocean planets-Mars, a number of icy satellites, Pluto, and other trans-neptunian objects-and applying Earth-like material properties and cooling rates, we find depths of circulation are more than an order of magnitude greater than in Earth. In Europa and Enceladus, tidal flexing may drive hydrothermal circulation and, in Europa, may generate heat on the same order as present-day radiogenic heat flux at Earth's surface. In all objects, progressive serpentinization generates heat on a globally averaged basis at a fraction of a percent of present-day radiogenic heating and hydrogen is produced at rates between 10(9) and 10(10) molecules cm(2) s(1).
Collapse
Affiliation(s)
- Steve Vance
- Astrobiology Program and Department of Earth & Space Sciences, University of Washington, Seattle, Washington, USA.
| | | | | | | | | | | |
Collapse
|
20
|
Hand KP, Chyba CF, Carlson RW, Cooper JF. Clathrate hydrates of oxidants in the ice shell of Europa. ASTROBIOLOGY 2006; 6:463-82. [PMID: 16805702 DOI: 10.1089/ast.2006.6.463] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Europa's icy surface is radiolytically modified by high-energy electrons and ions, and photolytically modified by solar ultraviolet photons. Observations from the Galileo Near Infrared Mapping Spectrometer, ground-based telescopes, the International Ultraviolet Explorer, and the Hubble Space Telescope, along with laboratory experiment results, indicate that the production of oxidants, such as H2O2, O2, CO2, and SO2, is a consequence of the surface radiolytic chemistry. Once created, some of the products may be entrained deeper into the ice shell through impact gardening or other resurfacing processes. The temperature and pressure environments of regions within the europan hydrosphere are expected to permit the formation of mixed clathrate compounds. The formation of carbon dioxide and sulfur dioxide clathrates has been examined in some detail. Here we add to this analysis by considering oxidants produced radiolytically on the surface of Europa. Our results indicate that the bulk ice shell could have a approximately 1.7-7.6% by number contamination of oxidants resulting from radiolysis at the surface. Oxidant-hosting clathrates would consequently make up approximately 12-53% of the ice shell by number relative to ice, if oxidants were entrained throughout. We examine, in brief, the consequences of such contamination on bulk ice shell thickness and find that clathrate formation could lead to substantially thinner ice shells on Europa than otherwise expected. Finally, we propose that double occupancy of clathrate cages by O2 molecules could serve as an explanation for the observation of condensed-phase O2 on Europa. Clathrate-sealed, gas-filled bubbles in the near surface ice could also provide an effective trapping mechanism, though they cannot explain the 5771 A (O2)2 absorption.
Collapse
Affiliation(s)
- Kevin P Hand
- Department of Geological & Environmental Sciences, Stanford University, Stanford, California 94305, USA.
| | | | | | | |
Collapse
|
21
|
Durham WB, Stern LA, Kubo T, Kirby SH. Flow strength of highly hydrated Mg- and Na-sulfate hydrate salts, pure and in mixtures with water ice, with application to Europa. ACTA ACUST UNITED AC 2005. [DOI: 10.1029/2005je002475] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
22
|
Zolotov MY. A model for low-temperature biogeochemistry of sulfur, carbon, and iron on Europa. ACTA ACUST UNITED AC 2004. [DOI: 10.1029/2003je002194] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|