Journal ArticleDOI
Ongoing hydrothermal activities within Enceladus
Hsiang-Wen Hsu,Frank Postberg,Yasuhito Sekine,Takazo Shibuya,Sascha Kempf,Mihaly Horanyi,Antal Juhász,Nicolas Altobelli,Katsuhiko Suzuki,Yuka Masaki,Tatsu Kuwatani,Shogo Tachibana,Sin Iti Sirono,Georg Moragas-Klostermeyer,Ralf Srama +14 more
TLDR
Analysis of silicon-rich, nanometre-sized dust particles (so-called stream particles) that stand out from the water-ice-dominated objects characteristic of Saturn indicate ongoing high-temperature (>90 °C) hydrothermal reactions associated with global-scale geothermal activity that quickly transports hydroThermal products from the ocean floor at a depth of at least 40 kilometres up to the plume of Enceladus.Abstract:
Analysis of silicon-rich, nanometre-sized dust particles near Saturn shows them to consist of silica, which was initially embedded in icy grains emitted from Enceladus’ subsurface waters and released by sputter erosion in Saturn’s E ring; their properties indicate their ongoing formation and transport by high-temperature hydrothermal reactions from the ocean floor and up into the plume of Enceladus. Hsiang-Wen Hsu et al. have analysed the silicon-rich, nanometre-sized dust stream particles in the Saturnian system using the Cosmic Dust Analyser (CDA) onboard the Cassini spacecraft. With the help of experiments and modelling, the particles are interpreted as silica grains that were initially embedded in the icy plume emitted from subsurface waters on Enceladus and released by sputter erosion in Saturn's E ring. Their properties indicate their formation and transport by high-temperature hydrothermal reactions from the ocean floor and up into the plume of Enceladus. Detection of sodium-salt-rich ice grains emitted from the plume of the Saturnian moon Enceladus suggests that the grains formed as frozen droplets from a liquid water reservoir that is, or has been, in contact with rock1,2. Gravitational field measurements suggest a regional south polar subsurface ocean of about 10 kilometres thickness located beneath an ice crust 30 to 40 kilometres thick3. These findings imply rock–water interactions in regions surrounding the core of Enceladus. The resulting chemical ‘footprints’ are expected to be preserved in the liquid and subsequently transported upwards to the near-surface plume sources, where they eventually would be ejected and could be measured by a spacecraft4. Here we report an analysis of silicon-rich, nanometre-sized dust particles5,6,7,8 (so-called stream particles) that stand out from the water-ice-dominated objects characteristic of Saturn. We interpret these grains as nanometre-sized SiO2 (silica) particles, initially embedded in icy grains emitted from Enceladus’ subsurface waters and released by sputter erosion in Saturn’s E ring. The composition and the limited size range (2 to 8 nanometres in radius) of stream particles indicate ongoing high-temperature (>90 °C) hydrothermal reactions associated with global-scale geothermal activity that quickly transports hydrothermal products from the ocean floor at a depth of at least 40 kilometres up to the plume of Enceladus.read more
Citations
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Journal ArticleDOI
Cassini finds molecular hydrogen in the Enceladus plume: Evidence for hydrothermal processes.
J. Hunter Waite,Christopher R. Glein,Rebecca Perryman,Ben Teolis,Brian Magee,Greg Miller,J. Grimes,Mark E. Perry,Kelly E. Miller,Alexis Bouquet,Jonathan I. Lunine,Tim Brockwell,Scott Bolton +12 more
TL;DR: The Ion Neutral Mass Spectrometer onboard the Cassini spacecraft is used to detect molecular hydrogen in the plume of escaping material on Enceladus, finding that the most plausible source of this hydrogen is ongoing hydrothermal reactions of rock containing reduced minerals and organic materials.
Journal ArticleDOI
Enceladus's measured physical libration requires a global subsurface ocean
Peter C. Thomas,Radwan Tajeddine,Matthew S. Tiscareno,Matthew S. Tiscareno,Joseph A. Burns,J. Joseph,Thomas J. Loredo,Paul Helfenstein,Carolyn C. Porco +8 more
TL;DR: In this paper, the authors used measurements of control points across the surface of Enceladus accumulated over seven years of spacecraft observations to determine the satellite's precise rotation state, finding a forced physical libration of 0.120 ± 0.014° (2σ).
Journal ArticleDOI
Living at the Extremes: Extremophiles and the Limits of Life in a Planetary Context.
Nancy Merino,Heidi S. Aronson,D.P. Bojanova,Jayme Feyhl-Buska,Michael L. Wong,Shu Zhang,Donato Giovannelli +6 more
TL;DR: The current state of knowledge for the biospace in which life operates on Earth is reviewed and discussed in a planetary context, highlighting knowledge gaps and areas of opportunity.
Journal ArticleDOI
Macromolecular organic compounds from the depths of Enceladus
Frank Postberg,Frank Postberg,Nozair Khawaja,Bernd Abel,Gaël Choblet,Christopher R. Glein,Murthy S. Gudipati,Bryana L. Henderson,Hsiang-Wen Hsu,Sascha Kempf,Fabian Klenner,Georg Moragas-Klostermeyer,Brian Magee,Brian Magee,Lenz Nölle,Mark E. Perry,René Reviol,Jürgen Schmidt,Ralf Srama,Ferdinand Stolz,Ferdinand Stolz,Gabriel Tobie,Mario Trieloff,J. Hunter Waite +23 more
TL;DR: The detection of complex organic molecules with masses higher than 200 atomic mass units in ice grains emitted from Enceladus indicates the presence of a thin organic-rich layer on top of the moon’s subsurface ocean.
Journal ArticleDOI
Habitability: a review
Charles S. Cockell,T. Bush,Casey Bryce,S. Direito,Mark Fox-Powell,Jesse P. Harrison,Helmut Lammer,Hanna Landenmark,Javier Martin-Torres,Natasha Nicholson,Lena Noack,Jack T. O'Malley-James,Samuel J. Payler,Andrew Rushby,Toby Samuels,Petra Schwendner,Jennifer Wadsworth,María Paz Zorzano +17 more
TL;DR: This review on habitability defines it as the ability of an environment to support the activity of at least one known organism and adopts a binary definition of "habitability" and a "habitable environment".
References
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Meteorites and the Early Solar System
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Journal ArticleDOI
Sodium salts in E-ring ice grains from an ocean below the surface of Enceladus
Frank Postberg,Sascha Kempf,Jürgen Schmidt,Nikolai V. Brilliantov,A. Beinsen,Bernd Abel,Udo Buck,Ralf Srama +7 more
TL;DR: The identification of a population of E-ring grains that are rich in sodium salts, which can arise only if the plumes originate from liquid water, and the abundance of various salt components in these particles exhibit a compelling similarity to the predicted composition of a subsurface Enceladus ocean in contact with its rock core.
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Carolyn C. Porco,Paul Helfenstein,Peter C. Thomas,Andrew P. Ingersoll,Jack Wisdom,Robert West,Gerhard Neukum,Tilmann Denk,Roland Wagner,Thomas Roatsch,Susan W. Kieffer,Elizabeth P. Turtle,Alfred S. McEwen,Torrence V. Johnson,Julie A. Rathbun,J. Veverka,Daren Wilson,Jason Perry,Joseph N. Spitale,André Brahic,Joseph A. Burns,Anthony D. DelGenio,Luke Dones,Carl D. Murray,Steven W. Squyres +24 more