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Klenner F, Bönigk J, Napoleoni M, Hillier J, Khawaja N, Olsson-Francis K, Cable ML, Malaska MJ, Kempf S, Abel B, Postberg F. How to identify cell material in a single ice grain emitted from Enceladus or Europa. SCIENCE ADVANCES 2024; 10:eadl0849. [PMID: 38517965 PMCID: PMC10959401 DOI: 10.1126/sciadv.adl0849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 02/20/2024] [Indexed: 03/24/2024]
Abstract
Icy moons like Enceladus, and perhaps Europa, emit material sourced from their subsurface oceans into space via plumes of ice grains and gas. Both moons are prime targets for astrobiology investigations. Cassini measurements revealed a large compositional diversity of emitted ice grains with only 1 to 4% of Enceladus's plume ice grains containing organic material in high concentrations. Here, we report experiments simulating mass spectra of ice grains containing one bacterial cell, or fractions thereof, as encountered by advanced instruments on board future space missions to Enceladus or Europa, such as the SUrface Dust Analyzer onboard NASA's upcoming Europa Clipper mission at flyby speeds of 4 to 6 kilometers per second. Mass spectral signals characteristic of the bacteria are shown to be clearly identifiable by future missions, even if an ice grain contains much less than one cell. Our results demonstrate the advantage of analyses of individual ice grains compared to a diluted bulk sample in a heterogeneous plume.
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Affiliation(s)
- Fabian Klenner
- Department of Earth and Space Sciences, University of Washington, Seattle, WA, USA
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
| | - Janine Bönigk
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
| | - Maryse Napoleoni
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
| | - Jon Hillier
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
| | - Nozair Khawaja
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
| | - Karen Olsson-Francis
- Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes, UK
| | - Morgan L. Cable
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Michael J. Malaska
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Sascha Kempf
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
| | - Bernd Abel
- Institute of Chemical Technology, University of Leipzig, Leipzig, Germany
- Leibniz-Institute of Surface Engineering (IOM), Leipzig, Germany
| | - Frank Postberg
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
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2
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Perera LJ, Cockell CS. Dispersion of Bacteria by Low-Pressure Boiling: Life Detection in Enceladus' Plume Material. ASTROBIOLOGY 2023; 23:269-279. [PMID: 36689196 DOI: 10.1089/ast.2022.0009] [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
The plume of Enceladus is thought to originate from the dispersion of a liquid source beneath the icy crust. Cryovolcanic activity on Enceladus may present a direct way of accessing material originating from the potentially habitable subsurface ocean. One way to test the hypothesis of whether life is present within the ocean of Enceladus would be to investigate the plume material for the presence of microbial life. In this study, we investigated the entrainment of Bacillus subtilis within Enceladus-like fluids under boiling conditions caused by exposure of the fluids to low pressure. We show that boiling, associated with exposure of a fluid to low pressure, works as a mechanism for dispersing bacteria in Enceladus plume-like environments. Exposure of Enceladus-type fluids (0.01-0.1 molal Na2CO3 and 0.05-0.2 molal NaCl) to low pressure (5 mbar) results in the dispersion of bacteria in droplets that evaporate to produce particles of salt. We find that, for particles with radius (r) ≤ 10 μm, the number of dispersed particles containing cells was between 7.7% and 10.9%. However, for larger particles 10 < r ≤ 50 μm, 64.4% and 56.4% contained cells for lower and upper end-member solutions, respectively. Our results suggest that the gravity-induced size sorting of plume particles will result in plume deposits closer to the vent source containing a larger volume of biological material than within the plume. If life is present in the ocean of Enceladus, we would expect that it would be effectively entrained and deposited on the surface; therefore, it would be accessible with a surface-lander-based instrument.
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Affiliation(s)
- L J Perera
- UK Centre for Astrobiology, University of Edinburgh, Edinburgh, UK
| | - C S Cockell
- UK Centre for Astrobiology, University of Edinburgh, Edinburgh, UK
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3
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Dannenmann M, Klenner F, Bönigk J, Pavlista M, Napoleoni M, Hillier J, Khawaja N, Olsson-Francis K, Cable ML, Malaska MJ, Abel B, Postberg F. Toward Detecting Biosignatures of DNA, Lipids, and Metabolic Intermediates from Bacteria in Ice Grains Emitted by Enceladus and Europa. ASTROBIOLOGY 2023; 23:60-75. [PMID: 36454287 DOI: 10.1089/ast.2022.0063] [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
The reliable identification of biosignatures is key to the search for life elsewhere. On ocean worlds like Enceladus or Europa, this can be achieved by impact ionization mass spectrometers, such as the SUrface Dust Analyzer (SUDA) on board NASA's upcoming Europa Clipper mission. During spacecraft flybys, these instruments can sample ice grains formed from subsurface water and emitted by these moons. Previous laboratory analog experiments have demonstrated that SUDA-type instruments could identify amino acids, fatty acids, and peptides in ice grains and discriminate between their abiotic and biotic origins. Here, we report experiments simulating impact ionization mass spectra of ice grains containing DNA, lipids, and metabolic intermediates extracted from two bacterial cultures: Escherichia coli and Sphingopyxis alaskensis. Salty Enceladan or Europan ocean waters were simulated using matrices with different NaCl concentrations. Characteristic mass spectral signals, such as DNA nucleobases, are clearly identifiable at part-per-million-level concentrations. Mass spectra of all substances exhibit unambiguous biogenic patterns, which in some cases show significant differences between the two bacterial species. Sensitivity to the biosignatures decreases with increasing matrix salinity. The experimental parameters indicate that future impact ionization mass spectrometers will be most sensitive to the investigated biosignatures for ice grain encounter speeds of 4-6 km/s.
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Affiliation(s)
- Marie Dannenmann
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
- Department of Plant and Microbial Biology, University of Zurich, Zurich, Switzerland
| | - Fabian Klenner
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
| | - Janine Bönigk
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
| | - Miriam Pavlista
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
| | - Maryse Napoleoni
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
| | - Jon Hillier
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
| | - Nozair Khawaja
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
| | - Karen Olsson-Francis
- AstrobiologyOU, Faculty of Science, Technology, Engineering & Mathematics, The Open University, Milton Keynes, United Kingdom
| | - Morgan L Cable
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Michael J Malaska
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Bernd Abel
- Leibniz-Institute of Surface Engineering (IOM), Leipzig, Germany
- Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry, Leipzig University, Leipzig, Germany
| | - Frank Postberg
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
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4
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Salter TL, Watson JS, Waite JH, Sephton MA. Hydrothermal Processing of Microorganisms: Mass Spectral Signals of Degraded Biosignatures for Life Detection on Icy Moons. ACS EARTH & SPACE CHEMISTRY 2022; 6:2508-2518. [PMID: 36303715 PMCID: PMC9589906 DOI: 10.1021/acsearthspacechem.2c00213] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/30/2022] [Accepted: 09/12/2022] [Indexed: 06/16/2023]
Abstract
Life detection missions to the outer solar system are concentrating on the icy moons of Jupiter and Saturn and their inferred subsurface oceans. Access to evidence of habitability, and possibly even life, is facilitated by the ejection of subsurface material in plumes and outgassing fissures. Orbiting spacecraft can intersect the plume material or detect past sputtered remnants of outgassed products and analyze the contents using instruments such as mass spectrometers. Hydrothermalism has been proposed for the subsurface environments of icy moons, and the organic remains of any associated life would be expected to suffer some degradation through hydrothermalism, radiolysis, or spacecraft flyby impact fragmentation. Hydrothermalism is treated here for the first time in the context of the Europa Clipper mission. To assess the influence of hydrothermalism on the ability of orbiting mass spectrometers to detect degrading signals of life, we have subjected Earth microorganisms to laboratory hydrothermal processing. The processed microorganism samples were then analyzed using gas chromatography-mass spectrometry (GC-MS), and mass spectra were generated. Certain compound classes, such as carbohydrates and proteins, are significantly altered by hydrothermal processing, resulting in small one-ring and two-ring aromatic compounds such as indoles and phenols. However, lipid fragments, such as fatty acids, retain their fidelity, and their provenance is easily recognized as biological in origin. Our data indicate that mass spectrometry measurements in the plumes of icy moons, using instruments such as the MAss Spectrometer for Planetary Exploration (MASPEX) onboard the upcoming Europa Clipper mission, can reveal the presence of life even after significant degradation by hydrothermal processing has taken place.
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Affiliation(s)
- Tara L. Salter
- Impacts
and Astromaterials Research Centre, Department of Earth Science and
Engineering, Imperial College London, London SW7 2AZ, United Kingdom
| | - Jonathan S. Watson
- Impacts
and Astromaterials Research Centre, Department of Earth Science and
Engineering, Imperial College London, London SW7 2AZ, United Kingdom
| | - J. Hunter Waite
- Space
Science and Engineering Division, Southwest
Research Institute, San Antonio, Texas 78238, United States
| | - Mark A. Sephton
- Impacts
and Astromaterials Research Centre, Department of Earth Science and
Engineering, Imperial College London, London SW7 2AZ, United Kingdom
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5
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Neveu M, Coker RF, Lorenz RD, MacKenzie SM, Lunine JI, Davila AF. Planetary Protection Assessment of Radioisotope Thermoelectric Generator (RTG)-Powered Landed Missions to Ocean Worlds: Application to Enceladus. ASTROBIOLOGY 2022; 22:1047-1060. [PMID: 35972349 DOI: 10.1089/ast.2020.2432] [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: 06/15/2023]
Abstract
Landed missions to icy worlds with a subsurface liquid water ocean must meet planetary protection requirements and ensure a sufficiently small likelihood of any microorganism-bearing part of the landed element reaching the ocean. A higher bound on this likelihood is set by the potential for radioisotope thermoelectric generator (RTG) power sources, the hottest possible landed element, to melt through the ice shell and reach the ocean. In this study, we quantify this potential as a function of three key parameters: surface temperature, ice shell thickness (i.e., heat flux through the shell), and thickness of a porous (insulating) snow or regolith cover. Although the model we describe can be applied to any ocean world, we present results in the context of a landed mission concept to the south polar terrain of Saturn's moon Enceladus. In this particular context, we discuss planetary protection considerations for landing site selection. The likelihood of forward microbial contamination of Enceladus' ocean by an RTG-powered landed mission can be made sufficiently low to not undermine compliance with the planetary protection policy.
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Affiliation(s)
- Marc Neveu
- Department of Astronomy, University of Maryland, College Park, Maryland, USA
- Planetary Environments Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - Robert F Coker
- Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland, USA
| | - Ralph D Lorenz
- Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland, USA
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6
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von Hegner I. Extreme Exoworlds and the Extremophile Paradox. ASTROBIOLOGY 2022; 22:926-936. [PMID: 35787001 DOI: 10.1089/ast.2021.0153] [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: 06/15/2023]
Abstract
Extremophiles have gained prominence by providing an experimental approach to astrobiology. Extremophiles gain equal value by being part of a framework for high-level characterization of the evolutionary mechanisms that must necessarily restrict or promote their emergence and presence on solar system bodies. Thus, extremophiles exist in extreme environments, and therein lies the paradox: extremophiles can only live in extreme environments but are not able to originate in such environments. Therefore, even though the range of extremophile capabilities in extreme environments is wider than that in mesophiles, the range of their emergence possibilities is still equally restricted. Therefore, even if one locates an extreme exoworld where terrestrial extremophiles could live here-and-now, it can be predicted that no extremophile analogs are present anyway. Furthermore, it is possible for a world to be uninhabited, yet be habitable, and therein arises the extreme environment paradox: an extreme environment can sustain chemical evolution as well as arriving non-native life, yet native life cannot be built up in that very environment. Thus, life may exist on an extraterrestrial extreme world (if imported there), and chemical evolution may be present on that world. However, it can be predicted that there is no native life anyway. This situation can be predicted to function as a chemosignature and eventually as a biosignature. However, the fact that a non-native extremopile in principle can exist in extreme environments may demonstrate that the intermediate step between chemical evolution and extremophiles can still occur in the form of a statistical deviation. In summary, the use of extremophiles as analogs to extraterrestrial life has limitations due to the very conditions evolution operates under, although analysis of these conditions provides conceptual tools for the search for life elsewhere in the Solar System and beyond.
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7
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MacKenzie SM, Neveu M, Davila AF, Lunine JI, Cable ML, Phillips-Lander CM, Eigenbrode JL, Waite JH, Craft KL, Hofgartner JD, McKay CP, Glein CR, Burton D, Kounaves SP, Mathies RA, Vance SD, Malaska MJ, Gold R, German CR, Soderlund KM, Willis P, Freissinet C, McEwen AS, Brucato JR, de Vera JPP, Hoehler TM, Heldmann J. Science Objectives for Flagship-Class Mission Concepts for the Search for Evidence of Life at Enceladus. ASTROBIOLOGY 2022; 22:685-712. [PMID: 35290745 PMCID: PMC9233532 DOI: 10.1089/ast.2020.2425] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Cassini revealed that Saturn's Moon Enceladus hosts a subsurface ocean that meets the accepted criteria for habitability with bio-essential elements and compounds, liquid water, and energy sources available in the environment. Whether these conditions are sufficiently abundant and collocated to support life remains unknown and cannot be determined from Cassini data. However, thanks to the plume of oceanic material emanating from Enceladus' south pole, a new mission to Enceladus could search for evidence of life without having to descend through kilometers of ice. In this article, we outline the science motivations for such a successor to Cassini, choosing the primary science goal to be determining whether Enceladus is inhabited and assuming a resource level equivalent to NASA's Flagship-class missions. We selected a set of potential biosignature measurements that are complementary and orthogonal to build a robust case for any life detection result. This result would be further informed by quantifications of the habitability of the environment through geochemical and geophysical investigations into the ocean and ice shell crust. This study demonstrates that Enceladus' plume offers an unparalleled opportunity for in situ exploration of an Ocean World and that the planetary science and astrobiology community is well equipped to take full advantage of it in the coming decades.
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Affiliation(s)
- Shannon M. MacKenzie
- Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA
- Address correspondence to: Shannon M. MacKenzie, Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA
| | - Marc Neveu
- Department of Astronomy, University of Maryland, College Park, Maryland, USA
- Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - Alfonso F. Davila
- Division of Space Science and Astrobiology, NASA Ames Research Center, Moffett Field, California, USA
| | - Jonathan I. Lunine
- Department of Astronomy, Cornell University, Ithaca, New York, USA
- Carl Sagan Institute, Cornell University, Ithaca, New York, USA
| | - Morgan L. Cable
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | | | - Jennifer L. Eigenbrode
- Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - J. Hunter Waite
- Space Science and Engineering Division, Southwest Research Institute, San Antonio, Texas, USA
| | - Kate L. Craft
- Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA
| | - Jason D. Hofgartner
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Chris P. McKay
- Division of Space Science and Astrobiology, NASA Ames Research Center, Moffett Field, California, USA
| | - Christopher R. Glein
- Space Science and Engineering Division, Southwest Research Institute, San Antonio, Texas, USA
| | - Dana Burton
- Department of Anthropology, George Washington University, Washington, District of Columbia, USA
| | | | - Richard A. Mathies
- Chemistry Department and Space Sciences Laboratory, University of California, Berkeley, Berkeley, California, USA
| | - Steven D. Vance
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Michael J. Malaska
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Robert Gold
- Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA
| | - Christopher R. German
- Department of Geology & Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
| | - Krista M. Soderlund
- Institute for Geophysics, Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas, USA
| | - Peter Willis
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | | | - Alfred S. McEwen
- Lunar and Planetary Lab, University of Arizona, Tucson, Arizona, USA
| | | | - Jean-Pierre P. de Vera
- Space Operations and Astronaut Training, MUSC, German Aerospace Center (DLR), Cologne, Germany
| | - Tori M. Hoehler
- Division of Space Science and Astrobiology, NASA Ames Research Center, Moffett Field, California, USA
| | - Jennifer Heldmann
- Division of Space Science and Astrobiology, NASA Ames Research Center, Moffett Field, California, USA
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8
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Salter TL, Magee BA, Waite JH, Sephton MA. Mass Spectrometric Fingerprints of Bacteria and Archaea for Life Detection on Icy Moons. ASTROBIOLOGY 2022; 22:143-157. [PMID: 35021862 DOI: 10.1089/ast.2020.2394] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The icy moons of the outer Solar System display evidence of subsurface liquid water and, therefore, potential habitability for life. Flybys of Saturn's moon Enceladus by the Cassini spacecraft have provided measurements of material from plumes that suggest hydrothermal activity and the presence of organic matter. Jupiter's moon Europa may have similar plumes and is the target for the forthcoming Europa Clipper mission that carries a high mass resolution and high sensitivity mass spectrometer, called the MAss Spectrometer for Planetary EXploration (MASPEX), with the capability for providing detailed characterization of any organic materials encountered. We have performed a series of experiments using pyrolysis-gas chromatography-mass spectrometry to characterize the mass spectrometric fingerprints of microbial life. A range of extremophile Archaea and Bacteria have been analyzed and the laboratory data converted to MASPEX-type signals. Molecular characteristics of protein, carbohydrate, and lipid structures were detected, and the characteristic fragmentation patterns corresponding to these different biological structures were identified. Protein pyrolysis fragments included phenols, nitrogen heterocycles, and cyclic dipeptides. Oxygen heterocycles, such as furans, were detected from carbohydrates. Our data reveal how mass spectrometry on Europa Clipper can aid in the identification of the presence of life, by looking for characteristic bacterial fingerprints that are similar to those from simple Earthly organisms.
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Affiliation(s)
- Tara L Salter
- Impacts and Astromaterials Research Centre, Department of Earth Science and Engineering, Imperial College London, London, United Kingdom
| | - Brian A Magee
- Space Science and Engineering Division, Southwest Research Institute, Boulder, Colorado, USA
| | - J Hunter Waite
- Space Science and Engineering Division, Southwest Research Institute, San Antonio, Texas, USA
| | - Mark A Sephton
- Impacts and Astromaterials Research Centre, Department of Earth Science and Engineering, Imperial College London, London, United Kingdom
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9
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Tenelanda-Osorio LI, Parra JL, Cuartas-Restrepo P, Zuluaga JI. Enceladus as a Potential Niche for Methanogens and Estimation of Its Biomass. Life (Basel) 2021; 11:1182. [PMID: 34833058 PMCID: PMC8624164 DOI: 10.3390/life11111182] [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: 08/24/2021] [Revised: 09/24/2021] [Accepted: 10/14/2021] [Indexed: 11/17/2022] Open
Abstract
Enceladus is a potential target for future astrobiological missions. NASA's Cassini spacecraft demonstrated that the Saturnian moon harbors a salty ocean beneath its icy crust and the existence and analysis of the plume suggest water-rock reactions, consistent with the possible presence of hydrothermal vents. Particularly, the plume analysis revealed the presence of molecular hydrogen, which may be used as an energy source by microorganisms ( e.g., methanogens). This could support the possibility that populations of methanogens could establish in such environments if they exist on Enceladus. We took a macroscale approximation using ecological niche modeling to evaluate whether conditions suitable for methanogenic archaea on Earth are expected in Enceladus. In addition, we employed a new approach for computing the biomass using the Monod growth model. The response curves for the environmental variables performed well statistically, indicating that simple correlative models may be used to approximate large-scale distributions of these genera on Earth. We found that the potential hydrothermal conditions on Enceladus fit within the macroscale conditions identified as suitable for methanogens on Earth, and estimated a concentration of 1010-1011 cells/cm3.
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Affiliation(s)
- Laura I. Tenelanda-Osorio
- Grupo de Estudios en Astrobiología AMEBA, Planetario de Medellín, Medellín 050010, Colombia;
- Grupo de Ecología y Evolución de Vertebrados, Instituto de Biología-FCEN, Universidad de Antioquia, Medellín 050010, Colombia;
- Solar, Earth and Planetary Physics—SEAP, Instituto de Física-FCEN, Universidad de Antioquia, Medellín 050010, Colombia;
| | - Juan L. Parra
- Grupo de Ecología y Evolución de Vertebrados, Instituto de Biología-FCEN, Universidad de Antioquia, Medellín 050010, Colombia;
| | - Pablo Cuartas-Restrepo
- Solar, Earth and Planetary Physics—SEAP, Instituto de Física-FCEN, Universidad de Antioquia, Medellín 050010, Colombia;
| | - Jorge I. Zuluaga
- Grupo de Estudios en Astrobiología AMEBA, Planetario de Medellín, Medellín 050010, Colombia;
- Solar, Earth and Planetary Physics—SEAP, Instituto de Física-FCEN, Universidad de Antioquia, Medellín 050010, Colombia;
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10
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Quantitative evaluation of the feasibility of sampling the ice plumes at Enceladus for biomarkers of extraterrestrial life. Proc Natl Acad Sci U S A 2021; 118:2106197118. [PMID: 34493668 PMCID: PMC8449353 DOI: 10.1073/pnas.2106197118] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 08/02/2021] [Indexed: 11/30/2022] Open
Abstract
The search for organic biosignatures indicative of life elsewhere in our solar system is an exciting quest that, if successful, will have a profound impact on our biological uniqueness. Saturn’s icy moon Enceladus is a promising location for a second occurrence of life due to its salty subsurface ocean. Plumes that jet out through the ice surface vents provide an enticing opportunity to sample the underlying ocean for biomarkers. The experiments reported here provide accurate modeling of our ability to fly through these plumes to efficiently and nondestructively gather ice particles for biomolecular analysis. Our measured efficiencies demonstrate that Saturn and/or Enceladus orbital missions will gather sufficient ice to make meaningful measurement of biosignatures in the Enceladus plumes. Enceladus, an icy moon of Saturn, is a compelling destination for a probe seeking biosignatures of extraterrestrial life because its subsurface ocean exhibits significant organic chemistry that is directly accessible by sampling cryovolcanic plumes. State-of-the-art organic chemical analysis instruments can perform valuable science measurements at Enceladus provided they receive sufficient plume material in a fly-by or orbiter plume transit. To explore the feasibility of plume sampling, we performed light gas gun experiments impacting micrometer-sized ice particles containing a fluorescent dye biosignature simulant into a variety of soft metal capture surfaces at velocities from 800 m ⋅ s−1 up to 3 km ⋅ s−1. Quantitative fluorescence microscopy of the capture surfaces demonstrates organic capture efficiencies of up to 80 to 90% for isolated impact craters and of at least 17% on average on indium and aluminum capture surfaces at velocities up to 2.2 km ⋅ s−1. Our results reveal the relationships between impact velocity, particle size, capture surface, and capture efficiency for a variety of possible plume transit scenarios. Combined with sensitive microfluidic chemical analysis instruments, we predict that our capture system can be used to detect organic molecules in Enceladus plume ice at the 1 nM level—a sensitivity thought to be meaningful and informative for probing habitability and biosignatures.
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11
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Rouzie D, Lindensmith C, Nadeau J. Microscopic Object Classification through Passive Motion Observations with Holographic Microscopy. Life (Basel) 2021; 11:life11080793. [PMID: 34440537 PMCID: PMC8401815 DOI: 10.3390/life11080793] [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: 07/01/2021] [Revised: 07/31/2021] [Accepted: 08/01/2021] [Indexed: 11/16/2022] Open
Abstract
Digital holographic microscopy provides the ability to observe throughout a volume that is large compared to its resolution without the need to actively refocus to capture the entire volume. This enables simultaneous observations of large numbers of small objects within such a volume. We have constructed a microscope that can observe a volume of 0.4 µm × 0.4 µm × 1.0 µm with submicrometer resolution (in xy) and 2 µm resolution (in z) for observation of microorganisms and minerals in liquid environments on Earth and on potential planetary missions. Because environmental samples are likely to contain mixtures of inorganics and microorganisms of comparable sizes near the resolution limit of the instrument, discrimination between living and non-living objects may be difficult. The active motion of motile organisms can be used to readily distinguish them from non-motile objects (live or inorganic), but additional methods are required to distinguish non-motile organisms and inorganic objects that are of comparable size but different composition and structure. We demonstrate the use of passive motion to make this discrimination by evaluating diffusion and buoyancy characteristics of cells, styrene beads, alumina particles, and gas-filled vesicles of micron scale in the field of view.
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Affiliation(s)
- Devan Rouzie
- Department of Physics, Portland State University, 1719 SW 10th Ave., Portland, OR 97201, USA;
| | - Christian Lindensmith
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91125, USA;
| | - Jay Nadeau
- Department of Physics, Portland State University, 1719 SW 10th Ave., Portland, OR 97201, USA;
- Correspondence: ; Tel.: +1-503-795-8929
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12
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Seaton KM, Cable ML, Stockton AM. Analytical Chemistry in Astrobiology. Anal Chem 2021; 93:5981-5997. [PMID: 33835785 DOI: 10.1021/acs.analchem.0c04271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This Feature introduces and discusses the findings of key analytical techniques used to study planetary bodies in our solar system in the search for life beyond Earth, future missions planned for high-priority astrobiology targets in our solar system, and the challenges we face in performing these investigations.
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Affiliation(s)
- Kenneth Marshall Seaton
- School of Chemistry & Biochemistry, Georgia Institute of Technology, North Avenue NW, Atlanta, Georgia 30332, United States
| | - Morgan Leigh Cable
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, United States
| | - Amanda Michelle Stockton
- School of Chemistry & Biochemistry, Georgia Institute of Technology, North Avenue NW, Atlanta, Georgia 30332, United States
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13
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Jaramillo-Botero A, Cable ML, Hofmann AE, Malaska M, Hodyss R, Lunine J. Understanding Hypervelocity Sampling of Biosignatures in Space Missions. ASTROBIOLOGY 2021; 21:421-442. [PMID: 33749334 PMCID: PMC7994429 DOI: 10.1089/ast.2020.2301] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 11/09/2020] [Indexed: 05/08/2023]
Abstract
The atomic-scale fragmentation processes involved in molecules undergoing hypervelocity impacts (HVIs; defined as >3 km/s) are challenging to investigate via experiments and still not well understood. This is particularly relevant for the consistency of biosignals from small-molecular-weight neutral organic molecules obtained during solar system robotic missions sampling atmospheres and plumes at hypervelocities. Experimental measurements to replicate HVI effects on neutral molecules are challenging, both in terms of accelerating uncharged species and isolating the multiple transition states over very rapid timescales (<1 ps). Nonequilibrium first-principles-based simulations extend the range of what is possible with experiments. We report on high-fidelity simulations of the fragmentation of small organic biosignature molecules over the range v = 1-12 km/s, and demonstrate that the fragmentation fraction is a sensitive function of velocity, impact angle, molecular structure, impact surface material, and the presence of surrounding ice shells. Furthermore, we generate interpretable fragmentation pathways and spectra for velocity values above the fragmentation thresholds and reveal how organic molecules encased in ice grains, as would likely be the case for those in "ocean worlds," are preserved at even higher velocities than bare molecules. Our results place ideal spacecraft encounter velocities between 3 and 5 km/s for bare amino and fatty acids and within 4-6 km/s for the same species encased in ice grains and predict the onset of organic fragmentation in ice grains at >5 km/s, both consistent with recent experiments exploring HVI effects using impact-induced ionization and analysis via mass spectrometry and from the analysis of Enceladus organics in Cassini Data. From nanometer-sized ice Ih clusters, we establish that HVI energy is dissipated by ice casings through thermal resistance to the impact shock wave and that an upper fragmentation velocity limit exists at which ultimately any organic contents will be cleaved by the surrounding ice-this provides a fundamental path to characterize micrometer-sized ice grains. Altogether, these results provide quantifiable insights to bracket future instrument design and mission parameters.
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Affiliation(s)
- Andres Jaramillo-Botero
- Chemistry and Chemical Engineering Division, California Institute of Technology, Pasadena, California, USA
| | - Morgan L. Cable
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Amy E. Hofmann
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Michael Malaska
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Robert Hodyss
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Jonathan Lunine
- Department of Astronomy and Carl Sagan Institute, Cornell University, Ithaca, New York, USA
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14
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Klenner F, Postberg F, Hillier J, Khawaja N, Cable ML, Abel B, Kempf S, Glein CR, Lunine JI, Hodyss R, Reviol R, Stolz F. Discriminating Abiotic and Biotic Fingerprints of Amino Acids and Fatty Acids in Ice Grains Relevant to Ocean Worlds. ASTROBIOLOGY 2020; 20:1168-1184. [PMID: 32493049 DOI: 10.1089/ast.2019.2188] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Identifying and distinguishing between abiotic and biotic signatures of organic molecules such as amino acids and fatty acids is key to the search for life on extraterrestrial ocean worlds. Impact ionization mass spectrometers can potentially achieve this by sampling water ice grains formed from ocean water and ejected by moons such as Enceladus and Europa, thereby exploring the habitability of their subsurface oceans in spacecraft flybys. Here, we extend previous high-sensitivity laser-based analog experiments of biomolecules in pure water to investigate the mass spectra of amino acids and fatty acids at simulated abiotic and biotic relative abundances. To account for the complex background matrix expected to emerge from a salty Enceladean ocean that has been in extensive chemical exchange with a carbonaceous rocky core, other organic and inorganic constituents are added to the biosignature mixtures. We find that both amino acids and fatty acids produce sodiated molecular peaks in salty solutions. Under the soft ionization conditions expected for low-velocity (2-6 km/s) encounters of an orbiting spacecraft with ice grains, the unfragmented molecular spectral signatures of amino acids and fatty acids accurately reflect the original relative abundances of the parent molecules within the source solution, enabling characteristic abiotic and biotic relative abundance patterns to be identified. No critical interferences with other abiotic organic compounds were observed. Detection limits of the investigated biosignatures under Enceladus-like conditions are salinity dependent (decreasing sensitivity with increasing salinity), at the μM or nM level. The survivability and ionization efficiency of large organic molecules during impact ionization appear to be significantly improved when they are protected by a frozen water matrix. We infer from our experimental results that encounter velocities of 4-6 km/s are most appropriate for impact ionization mass spectrometers to detect and discriminate between abiotic and biotic signatures.
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Affiliation(s)
- Fabian Klenner
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
- Institute of Earth Sciences, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
| | - Frank Postberg
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
- Institute of Earth Sciences, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
| | - Jon Hillier
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
| | - Nozair Khawaja
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
- Institute of Earth Sciences, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
| | - Morgan L Cable
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Bernd Abel
- Leibniz-Institute of Surface Engineering, Leipzig, Germany
- Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry, Universität Leipzig, Leipzig, Germany
| | - Sascha Kempf
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado, USA
| | - Christopher R Glein
- Space Science and Engineering Division, Southwest Research Institute, San Antonio, Texas, USA
| | - Jonathan I Lunine
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
- Department of Astronomy and Carl Sagan Institute, Cornell University, Ithaca, New York, USA
| | - Robert Hodyss
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - René Reviol
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
- Institute of Earth Sciences, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
| | - Ferdinand Stolz
- Leibniz-Institute of Surface Engineering, Leipzig, Germany
- Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry, Universität Leipzig, Leipzig, Germany
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15
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Bywaters K, Stoker CR, Batista Do Nascimento N, Lemke L. Towards Determining Biosignature Retention in Icy World Plumes. Life (Basel) 2020; 10:life10040040. [PMID: 32316157 PMCID: PMC7235855 DOI: 10.3390/life10040040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 04/11/2020] [Accepted: 04/14/2020] [Indexed: 02/07/2023] Open
Abstract
With the discovery of the persistent jets of water being ejected to space from Enceladus, an understanding of the effect of the space environment on potential organisms and biosignatures in them is necessary for planning life detection missions. We experimentally determine the survivability of microbial cells in liquid medium when ejected into vacuum. Epifluorescence microscopy, using a lipid stain, and SEM imaging were used to interrogate the cellular integrity of E. coli after ejected through a pressurized nozzle into a vacuum chamber. The experimental samples showed a 94% decrease in visible intact E. coli cells but showed a fluorescence residue in the shape of the sublimated droplets that indicated the presence of lipids. The differences in the experimental conditions versus those expected on Enceladus should not change the analog value because the process a sample would undergo when ejected into space was representative. E. coli was selected for testing although other cell types could vary physiologically which would affect their response to a vacuum environment. More testing is needed to determine the dynamic range in concentration of cells expected to survive the plume environment. However, these results suggest that lipids may be directly detectable evidence of life in icy world plumes.
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Affiliation(s)
- Kathryn Bywaters
- SETI Institute, Moffett Field, CA 94043, USA
- Correspondence: (K.B.); (C.R.S.); Tel.: +1-650-604-2295 (K.B.); +1-650-604-6490 (C.R.S.)
| | - Carol R. Stoker
- NASA Ames Research Center, Space Science Division, Moffett Field, CA 94035, USA; (N.B.D.N.J.); (L.L.)
- Correspondence: (K.B.); (C.R.S.); Tel.: +1-650-604-2295 (K.B.); +1-650-604-6490 (C.R.S.)
| | | | - Lawrence Lemke
- NASA Ames Research Center, Space Science Division, Moffett Field, CA 94035, USA; (N.B.D.N.J.); (L.L.)
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16
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Waller SE, Belousov A, Kidd RD, Nikolić D, Madzunkov SM, Wiley JS, Darrach MR. Chemical Ionization Mass Spectrometry: Applications for the In Situ Measurement of Nonvolatile Organics at Ocean Worlds. ASTROBIOLOGY 2019; 19:1196-1210. [PMID: 31347911 DOI: 10.1089/ast.2018.1961] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A new technique that has applications for the detection of nonvolatile organics on Ocean Worlds has been developed. Here, liquid mixtures of fatty acids (FAs) and/or amino acids (AAs) are introduced directly into a miniature quadrupole ion trap mass spectrometer (QITMS) developed at Jet Propulsion Laboratory and analyzed. Two ionization methods, electron impact and chemical ionization (EI and CI, respectively), are compared and contrasted. Further, multiple CI reagents are tested to explore their potential to "soften" ionization of FAs and AAs. Both EI and CI yield mass spectra that bear signatures of FAs or AAs; however, soft CI yields significantly cleaner mass spectra that are easier to interpret. The combination of soft CI with tandem mass spectrometry (MS/MS) has also been demonstrated for AAs, generating "fingerprint" mass spectra of fragments from protonated parent ions. To mimic potential Ocean World conditions, water is used as the primary collision gas in MS/MS experiments. This technique has the potential for the in situ analysis of molecules in the cryogenic plumes of Ocean Worlds (e.g., Enceladus) and comets with the ultimate goal of detecting potential biosignatures.
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Affiliation(s)
- Sarah E Waller
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
| | - Anton Belousov
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
| | - Richard D Kidd
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
| | - Dragan Nikolić
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
| | - Stojan M Madzunkov
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
| | - Joshua S Wiley
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
| | - Murray R Darrach
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
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17
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Akob DM, Sutton JM, Fierst JL, Haase KB, Baesman S, Luther GW, Miller LG, Oremland RS. Acetylenotrophy: a hidden but ubiquitous microbial metabolism? FEMS Microbiol Ecol 2018; 94:5026170. [PMID: 29933435 PMCID: PMC7190893 DOI: 10.1093/femsec/fiy103] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 05/29/2018] [Indexed: 11/12/2022] Open
Abstract
Acetylene (IUPAC name: ethyne) is a colorless, gaseous hydrocarbon, composed of two triple bonded carbon atoms attached to hydrogens (C2H2). When microbiologists and biogeochemists think of acetylene, they immediately think of its use as an inhibitory compound of certain microbial processes and a tracer for nitrogen fixation. However, what is less widely known is that anaerobic and aerobic microorganisms can degrade acetylene, using it as a sole carbon and energy source and providing the basis of a microbial food web. Here, we review what is known about acetylene degrading organisms and introduce the term 'acetylenotrophs' to refer to the microorganisms that carry out this metabolic pathway. In addition, we review the known environmental sources of acetylene and postulate the presence of an hidden acetylene cycle. The abundance of bacteria capable of using acetylene and other alkynes as an energy and carbon source suggests that there are energy cycles present in the environment that are driven by acetylene and alkyne production and consumption that are isolated from atmospheric exchange. Acetylenotrophs may have developed to leverage the relatively high concentrations of acetylene in the pre-Cambrian atmosphere, evolving later to survive in specialized niches where acetylene and other alkynes were produced.
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Affiliation(s)
- Denise M Akob
- U. S. Geological Survey, 12201 Sunrise Valley Dr, MS 430, Reston, VA 20192 USA
| | - John M Sutton
- Department of Biological Sciences, The University of Alabama, SEC 2328, Box 870344, Tuscaloosa, AL 35487 USA
| | - Janna L Fierst
- Department of Biological Sciences, The University of Alabama, SEC 2328, Box 870344, Tuscaloosa, AL 35487 USA
| | - Karl B Haase
- U. S. Geological Survey, 12201 Sunrise Valley Dr, MS 430, Reston, VA 20192 USA
| | - Shaun Baesman
- U. S. Geological Survey, 345 Middlefield Road, MS 480, Menlo Park, CA 94025 USA
| | - George W Luther
- School of Marine Science and Policy, University of Delaware, 700 Pilottown Road, Cannon Laboratory 218, Lewes, DE 19958, USA
| | - Laurence G Miller
- U. S. Geological Survey, 345 Middlefield Road, MS 480, Menlo Park, CA 94025 USA
| | - Ronald S Oremland
- U. S. Geological Survey, 345 Middlefield Road, MS 480, Menlo Park, CA 94025 USA
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18
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Postberg F, Khawaja N, Abel B, Choblet G, Glein CR, Gudipati MS, Henderson BL, Hsu HW, Kempf S, Klenner F, Moragas-Klostermeyer G, Magee B, Nölle L, Perry M, Reviol R, Schmidt J, Srama R, Stolz F, Tobie G, Trieloff M, Waite JH. Macromolecular organic compounds from the depths of Enceladus. Nature 2018; 558:564-568. [PMID: 29950623 PMCID: PMC6027964 DOI: 10.1038/s41586-018-0246-4] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 03/23/2018] [Indexed: 11/13/2022]
Abstract
Saturn's moon Enceladus harbours a global water ocean 1 , which lies under an ice crust and above a rocky core 2 . Through warm cracks in the crust 3 a cryo-volcanic plume ejects ice grains and vapour into space4-7 that contain materials originating from the ocean8,9. Hydrothermal activity is suspected to occur deep inside the porous core10-12, powered by tidal dissipation 13 . So far, only simple organic compounds with molecular masses mostly below 50 atomic mass units have been observed in plume material6,14,15. Here we report observations of emitted ice grains containing concentrated and complex macromolecular organic material with molecular masses above 200 atomic mass units. The data constrain the macromolecular structure of organics detected in the ice grains and suggest the presence of a thin organic-rich film on top of the oceanic water table, where organic nucleation cores generated by the bursting of bubbles allow the probing of Enceladus' organic inventory in enhanced concentrations.
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Affiliation(s)
- Frank Postberg
- Institut für Geowissenschaften, Universität Heidelberg, Heidelberg, Germany.
- Klaus-Tschira-Labor für Kosmochemie, Universität Heidelberg, Heidelberg, Germany.
- Institut für Geologische Wissenschaften, Freie Universität Berlin, Berlin, Germany.
| | - Nozair Khawaja
- Institut für Geowissenschaften, Universität Heidelberg, Heidelberg, Germany
| | - Bernd Abel
- Leibniz-Institute für Oberflächenmodifizierung (IOM), Leipzig, Germany
| | - Gael Choblet
- Laboratoire de Planétologie et Géodynamique, UMR-CNRS 6112, Université de Nantes, Nantes, France
| | - Christopher R Glein
- Space Science and Engineering Division, Southwest Research Institute, San Antonio, TX, USA
| | - Murthy S Gudipati
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Bryana L Henderson
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Hsiang-Wen Hsu
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
| | - Sascha Kempf
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
| | - Fabian Klenner
- Institut für Geowissenschaften, Universität Heidelberg, Heidelberg, Germany
| | | | - Brian Magee
- Space Science and Engineering Division, Southwest Research Institute, San Antonio, TX, USA
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
| | - Lenz Nölle
- Institut für Geowissenschaften, Universität Heidelberg, Heidelberg, Germany
| | - Mark Perry
- Applied Physics Laboratory, Johns Hopkins University, Laurel, MD, USA
| | - René Reviol
- Institut für Geowissenschaften, Universität Heidelberg, Heidelberg, Germany
| | - Jürgen Schmidt
- Astronomy Research Unit, University of Oulu, Oulu, Finland
| | - Ralf Srama
- Institut für Raumfahrtsysteme, Universität Stuttgart, Stuttgart, Germany
| | - Ferdinand Stolz
- Leibniz-Institute für Oberflächenmodifizierung (IOM), Leipzig, Germany
- Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Leipzig, Germany
| | - Gabriel Tobie
- Laboratoire de Planétologie et Géodynamique, UMR-CNRS 6112, Université de Nantes, Nantes, France
| | - Mario Trieloff
- Institut für Geowissenschaften, Universität Heidelberg, Heidelberg, Germany
- Klaus-Tschira-Labor für Kosmochemie, Universität Heidelberg, Heidelberg, Germany
| | - J Hunter Waite
- Laboratoire de Planétologie et Géodynamique, UMR-CNRS 6112, Université de Nantes, Nantes, France
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19
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Taubner RS, Pappenreiter P, Zwicker J, Smrzka D, Pruckner C, Kolar P, Bernacchi S, Seifert AH, Krajete A, Bach W, Peckmann J, Paulik C, Firneis MG, Schleper C, Rittmann SKMR. Biological methane production under putative Enceladus-like conditions. Nat Commun 2018; 9:748. [PMID: 29487311 PMCID: PMC5829080 DOI: 10.1038/s41467-018-02876-y] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 01/04/2018] [Indexed: 11/18/2022] Open
Abstract
The detection of silica-rich dust particles, as an indication for ongoing hydrothermal activity, and the presence of water and organic molecules in the plume of Enceladus, have made Saturn's icy moon a hot spot in the search for potential extraterrestrial life. Methanogenic archaea are among the organisms that could potentially thrive under the predicted conditions on Enceladus, considering that both molecular hydrogen (H2) and methane (CH4) have been detected in the plume. Here we show that a methanogenic archaeon, Methanothermococcus okinawensis, can produce CH4 under physicochemical conditions extrapolated for Enceladus. Up to 72% carbon dioxide to CH4 conversion is reached at 50 bar in the presence of potential inhibitors. Furthermore, kinetic and thermodynamic computations of low-temperature serpentinization indicate that there may be sufficient H2 gas production to serve as a substrate for CH4 production on Enceladus. We conclude that some of the CH4 detected in the plume of Enceladus might, in principle, be produced by methanogens.
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Affiliation(s)
- Ruth-Sophie Taubner
- Archaea Biology and Ecogenomics Division, Department of Ecogenomics and Systems Biology, Universität Wien, 1090, Vienna, Austria
- Department of Astrophysics, Universität Wien, 1180, Vienna, Austria
| | - Patricia Pappenreiter
- Institute for Chemical Technology of Organic Materials, Johannes Kepler Universität Linz, 4040, Linz, Austria
| | - Jennifer Zwicker
- Department of Geodynamics and Sedimentology, Center for Earth Sciences, Universität Wien, 1090, Vienna, Austria
| | - Daniel Smrzka
- Department of Geodynamics and Sedimentology, Center for Earth Sciences, Universität Wien, 1090, Vienna, Austria
| | - Christian Pruckner
- Archaea Biology and Ecogenomics Division, Department of Ecogenomics and Systems Biology, Universität Wien, 1090, Vienna, Austria
| | - Philipp Kolar
- Archaea Biology and Ecogenomics Division, Department of Ecogenomics and Systems Biology, Universität Wien, 1090, Vienna, Austria
| | | | | | | | - Wolfgang Bach
- Geoscience Department, Universität Bremen, 28359, Bremen, Germany
| | - Jörn Peckmann
- Department of Geodynamics and Sedimentology, Center for Earth Sciences, Universität Wien, 1090, Vienna, Austria
- Institute for Geology, Center for Earth System Research and Sustainability, Universität Hamburg, 20146, Hamburg, Germany
| | - Christian Paulik
- Institute for Chemical Technology of Organic Materials, Johannes Kepler Universität Linz, 4040, Linz, Austria
| | - Maria G Firneis
- Department of Astrophysics, Universität Wien, 1180, Vienna, Austria
| | - Christa Schleper
- Archaea Biology and Ecogenomics Division, Department of Ecogenomics and Systems Biology, Universität Wien, 1090, Vienna, Austria
| | - Simon K-M R Rittmann
- Archaea Biology and Ecogenomics Division, Department of Ecogenomics and Systems Biology, Universität Wien, 1090, Vienna, Austria.
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20
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Judge P. A Novel Strategy to Seek Biosignatures at Enceladus and Europa. ASTROBIOLOGY 2017; 17:852-861. [PMID: 28872897 DOI: 10.1089/ast.2017.1667] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
A laboratory experiment is suggested in which conditions similar to those in the plume ejecta from Enceladus and, perhaps, Europa are established. With the use of infrared spectroscopy and polarimetry, the experiment might identify possible biomarkers in differential measurements of water from the open ocean, hydrothermal vents, and abiotic water samples. Should the experiment succeed, large telescopes could be used to acquire sensitive infrared spectra of the plumes of Enceladus and Europa, as the satellites transit the bright planetary disks. The extreme technical challenges encountered in so doing are similar to those of solar imaging spectropolarimetry. The desired signals are buried in noisy data in the presence of seeing-induced image motion and a changing natural source. Some differential measurements used for solar spectropolarimetry can achieve signal-to-noise ratios of 105 even in the presence of systematic errors 2 orders of magnitude larger. We review the techniques and likelihood of success of such an observing campaign with some of the world's largest ground-based telescopes, as well as the long-anticipated James Webb Space Telescope. We discuss the relative merits of the new 4 m Daniel K. Inouye Solar Telescope, as well as the James Webb Space Telescope and larger ground-based observatories, for observing the satellites of giant planets. As seen from near Earth, transits of Europa occur regularly, but transits of Enceladus will begin again only in 2022. Key Words: Spectroscopy-Spectropolarimetry-Life origins. Astrobiology 17, 852-861.
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21
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Mathies RA, Razu ME, Kim J, Stockton AM, Turin P, Butterworth A. Feasibility of Detecting Bioorganic Compounds in Enceladus Plumes with the Enceladus Organic Analyzer. ASTROBIOLOGY 2017; 17:902-912. [PMID: 28915087 PMCID: PMC5610425 DOI: 10.1089/ast.2017.1660] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Enceladus presents an excellent opportunity to detect organic molecules that are relevant for habitability as well as bioorganic molecules that provide evidence for extraterrestrial life because Enceladus' plume is composed of material from the subsurface ocean that has a high habitability potential and significant organic content. A primary challenge is to send instruments to Enceladus that can efficiently sample organic molecules in the plume and analyze for the most relevant molecules with the necessary detection limits. To this end, we present the scientific feasibility and engineering design of the Enceladus Organic Analyzer (EOA) that uses a microfluidic capillary electrophoresis system to provide sensitive detection of a wide range of relevant organic molecules, including amines, amino acids, and carboxylic acids, with ppm plume-detection limits (100 pM limits of detection). Importantly, the design of a capture plate that effectively gathers plume ice particles at encounter velocities from 200 m/s to 5 km/s is described, and the ice particle impact is modeled to demonstrate that material will be efficiently captured without organic decomposition. While the EOA can also operate on a landed mission, the relative technical ease of a fly-by mission to Enceladus, the possibility to nondestructively capture pristine samples from deep within the Enceladus ocean, plus the high sensitivity of the EOA instrument for molecules of bioorganic relevance for life detection argue for the inclusion of EOA on Enceladus missions. Key Words: Lab-on-a-chip-Organic biomarkers-Life detection-Planetary exploration. Astrobiology 17, 902-912.
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Affiliation(s)
- Richard A. Mathies
- Department of Chemistry, University of California at Berkeley, Berkeley, California
| | - Md Enayet Razu
- Department of Mechanical Engineering, Texas Tech University, Lubbock, Texas
| | - Jungkyu Kim
- Department of Mechanical Engineering, Texas Tech University, Lubbock, Texas
| | - Amanda M. Stockton
- Department of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia
| | - Paul Turin
- Berkeley Space Sciences Lab, University of California at Berkeley, Berkeley, California
| | - Anna Butterworth
- Berkeley Space Sciences Lab, University of California at Berkeley, Berkeley, California
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22
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Benner SA. Detecting Darwinism from Molecules in the Enceladus Plumes, Jupiter's Moons, and Other Planetary Water Lagoons. ASTROBIOLOGY 2017; 17:840-851. [PMID: 28665680 PMCID: PMC5610385 DOI: 10.1089/ast.2016.1611] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
To the astrobiologist, Enceladus offers easy access to a potential subsurface biosphere via the intermediacy of a plume of water emerging directly into space. A direct question follows: If we were to collect a sample of this plume, what in that sample, through its presence or its absence, would suggest the presence and/or absence of life in this exotic locale? This question is, of course, relevant for life detection in any aqueous lagoon that we might be able to sample. This manuscript reviews physical chemical constraints that must be met by a genetic polymer for it to support Darwinism, a process believed to be required for a chemical system to generate properties that we value in biology. We propose that the most important of these is a repeating backbone charge; a Darwinian genetic biopolymer must be a "polyelectrolyte." Relevant to mission design, such biopolymers are especially easy to recover and concentrate from aqueous mixtures for detection, simply by washing the aqueous mixtures across a polycharged support. Several device architectures are described to ensure that, once captured, the biopolymer meets two other requirements for Darwinism, homochirality and a small building block "alphabet." This approach is compared and contrasted with alternative biomolecule detection approaches that seek homochirality and constrained alphabets in non-encoded biopolymers. This discussion is set within a model for the history of the terran biosphere, identifying points in that natural history where these alternative approaches would have failed to detect terran life. Key Words: Enceladus-Life detection-Europa-Icy moon-Biosignatures-Polyelectrolyte theory of the gene. Astrobiology 17, 840-851.
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Affiliation(s)
- Steven A Benner
- Foundation for Applied Molecular Evolution , Alachua, Florida
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Porco CC. A Community Grows around the Geysering World of Enceladus. ASTROBIOLOGY 2017; 17:815-819. [PMID: 28742370 PMCID: PMC5610423 DOI: 10.1089/ast.2017.1711] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The discovery by NASA's Cassini mission at Saturn in 2005 of a large plume of material erupting from the south polar terrain of Enceladus, sourced within a subsurface ocean of salty liquid water laced with organic compounds, has brought together scientists from a diverse range of disciplines over the last decade to evaluate this small moon's potential for extraterrestrial life. The collection of papers published today in Astrobiology, as the mission draws to a close, is the outcome of our most recent meeting at UC Berkeley in June 2016. Key Words: Enceladus-Enceladus Focus Group-Ocean world-Search for biosignatures. Astrobiology 17, 815-819.
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Affiliation(s)
- Carolyn C Porco
- University of California , Berkeley, California
- Space Science Institute , Boulder, Colorado
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