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Downey BG, Nimmo F. Titan's spin state as a constraint on tidal dissipation. SCIENCE ADVANCES 2025; 11:eadl4741. [PMID: 39908389 DOI: 10.1126/sciadv.adl4741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Accepted: 01/07/2025] [Indexed: 02/07/2025]
Abstract
Tidal dissipation in satellites affects their orbital and rotational evolution and their ability to maintain subsurface oceans. However, a satellite's dissipation rate, parameterized by k2/Q, is hard to measure and is only known for the Moon and Io. Here, we use Titan's measured departure from its expected rotation state to infer k2/Q and its boundary layer dissipation parameter K/Cs. Over the likely range of ocean and ice shell thicknesses, we infer a K/Cs of 6.3 × 10-14 s-1 to 2.4 × 10-10 s-1, a k2/Q of 0.058 to 0.12, and a minimum dissipation factor Q ≈ 5. Titan's dissipation parameters are one to two orders of magnitude larger than the Moon's and suggest an interior with a low effective viscosity. Titan's dissipation rate implies that its eccentricity and inclination are damping rapidly, consistent with an excitation within the last ~350 Myr. The forthcoming Dragonfly lander could measure Titan's tidal response, and JUICE could use our approach to determine Ganymede's k2/Q.
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Affiliation(s)
- Brynna G Downey
- Southwest Research Institute, Boulder, CO 80302, USA
- Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz CA 95064, USA
| | - Francis Nimmo
- Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz CA 95064, USA
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2
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Tobie G, Auclair-Desrotour P, Běhounková M, Kervazo M, Souček O, Kalousová K. Tidal Deformation and Dissipation Processes in Icy Worlds. SPACE SCIENCE REVIEWS 2025; 221:6. [PMID: 39830012 PMCID: PMC11739232 DOI: 10.1007/s11214-025-01136-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Accepted: 12/30/2024] [Indexed: 01/22/2025]
Abstract
Tidal interactions play a key role in the dynamics and evolution of icy worlds. The intense tectonic activity of Europa and the eruption activity on Enceladus are clear examples of the manifestation of tidal deformation and associated dissipation. While tidal heating has long been recognized as a major driver in the activity of these icy worlds, the mechanism controlling how tidal forces deform the different internal layers and produce heat by tidal friction still remains poorly constrained. As tidal forcing varies with orbital characteristics (distance to the central planet, eccentricity, obliquity), the contribution of tidal heating to the internal heat budget can strongly change over geological timescales. In some circumstances, the tidally-produced heat can result in internal melting and surface activity taking various forms. Even in the absence of significant heat production, tidal deformation can be used to probe the interior structure, the tidal response of icy moons being strongly sensitive to their hydrosphere structure. In the present paper, we review the methods to compute tidal deformation and dissipation in the different layers composing icy worlds. After summarizing the main principle of tidal deformation and the different rheological models used to model visco-elastic tidal response, we describe the dissipation processes expected in rock-dominated cores, subsurface oceans and icy shells and highlight the potential effects of tidal heating in terms of thermal evolution and activity. We finally anticipate how data collected by future missions to Jupiter's and Saturn's moons could be used to constrain their tidal response and the consequences for past and present activities.
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Affiliation(s)
- G. Tobie
- Laboratoire de Planétologie et Géosciences, UMR 6112, CNRS, Nantes Université, Université d’Angers, Le Mans Université, Nantes, France
| | - P. Auclair-Desrotour
- IMCCE, CNRS, Observatoire de Paris, PSL University, Sorbonne Université, Paris, France
| | - M. Běhounková
- Faculty of Mathematics and Physics, Department of Geophysics, Charles University, V Holesšovičkách 2, Praha, Praha 8 180 00 Czech Republic
| | - M. Kervazo
- Laboratoire de Planétologie et Géosciences, UMR 6112, CNRS, Nantes Université, Université d’Angers, Le Mans Université, Nantes, France
| | - O. Souček
- Faculty of Mathematics and Physics, Mathematical Institute, Charles University, Sokolovská 83, Praha, Praha 8 186 75 Czech Republic
| | - K. Kalousová
- Faculty of Mathematics and Physics, Department of Geophysics, Charles University, V Holesšovičkách 2, Praha, Praha 8 180 00 Czech Republic
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3
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Styczinski MJ, Cooper ZS, Glaser DM, Lehmer O, Mierzejewski V, Tarnas J. Chapter 7: Assessing Habitability Beyond Earth. ASTROBIOLOGY 2024; 24:S143-S163. [PMID: 38498826 DOI: 10.1089/ast.2021.0097] [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: 03/20/2024]
Abstract
All known life on Earth inhabits environments that maintain conditions between certain extremes of temperature, chemical composition, energy availability, and so on (Chapter 6). Life may have emerged in similar environments elsewhere in the Solar System and beyond. The ongoing search for life elsewhere mainly focuses on those environments most likely to support life, now or in the past-that is, potentially habitable environments. Discussion of habitability is necessarily based on what we know about life on Earth, as it is our only example. This chapter gives an overview of the known and presumed requirements for life on Earth and discusses how these requirements can be used to assess the potential habitability of planetary bodies across the Solar System and beyond. We first consider the chemical requirements of life and potential feedback effects that the presence of life can have on habitable conditions, and then the planetary, stellar, and temporal requirements for habitability. We then review the state of knowledge on the potential habitability of bodies across the Solar System and exoplanets, with a particular focus on Mars, Venus, Europa, and Enceladus. While reviewing the case for the potential habitability of each body, we summarize the most prominent and impactful studies that have informed the perspective on where habitable environments are likely to be found.
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Affiliation(s)
- M J Styczinski
- University of Washington, Seattle, Washington, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Z S Cooper
- University of Washington, Seattle, Washington, USA
| | - D M Glaser
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, USA
| | - O Lehmer
- NASA Ames Research Center, Moffett Field, California, USA
| | - V Mierzejewski
- School of Earth and Space Exploration, Arizona State University, Arizona, USA
| | - J Tarnas
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
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Grefenstette N, Chou L, Colón-Santos S, Fisher TM, Mierzejewski V, Nural C, Sinhadc P, Vidaurri M, Vincent L, Weng MM. Chapter 9: Life as We Don't Know It. ASTROBIOLOGY 2024; 24:S186-S201. [PMID: 38498819 DOI: 10.1089/ast.2021.0103] [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: 03/20/2024]
Abstract
While Earth contains the only known example of life in the universe, it is possible that life elsewhere is fundamentally different from what we are familiar with. There is an increased recognition in the astrobiology community that the search for life should steer away from terran-specific biosignatures to those that are more inclusive to all life-forms. To start exploring the space of possibilities that life could occupy, we can try to dissociate life from the chemistry that composes it on Earth by envisioning how different life elsewhere could be in composition, lifestyle, medium, and form, and by exploring how the general principles that govern living systems on Earth might be found in different forms and environments across the Solar System. Exotic life-forms could exist on Mars or Venus, or icy moons like Europa and Enceladus, or even as a shadow biosphere on Earth. New perspectives on agnostic biosignature detection have also begun to emerge, allowing for a broader and more inclusive approach to seeking exotic life with unknown chemistry that is distinct from life as we know it on Earth.
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Affiliation(s)
- Natalie Grefenstette
- Santa Fe Institute, Santa Fe, New Mexico, USA
- Blue Marble Space Institute of Science, Seattle, Washington, USA
| | - Luoth Chou
- NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
- Georgetown University, Washington, DC, USA
| | | | - Theresa M Fisher
- School of Earth and Space Exploration, Arizona State University, Arizona, USA
| | | | - Ceren Nural
- Istanbul Technical University, Istanbul, Turkey
| | - Pritvik Sinhadc
- BEYOND: Center For Fundamental Concepts in Science, Arizona State University, Arizona, USA
- Dubai College, Dubai, United Arab Emirates
| | - Monica Vidaurri
- NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
- Howard University, DC, USA
| | - Lena Vincent
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Wisconsin, USA
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5
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Malas J, Russo DC, Bollengier O, Malaska MJ, Lopes RMC, Kenig F, Meyer-Dombard DR. Biological functions at high pressure: transcriptome response of Shewanella oneidensis MR-1 to hydrostatic pressure relevant to Titan and other icy ocean worlds. Front Microbiol 2024; 15:1293928. [PMID: 38414766 PMCID: PMC10896736 DOI: 10.3389/fmicb.2024.1293928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 01/25/2024] [Indexed: 02/29/2024] Open
Abstract
High hydrostatic pressure (HHP) is a key driver of life's evolution and diversification on Earth. Icy moons such as Titan, Europa, and Enceladus harbor potentially habitable high-pressure environments within their subsurface oceans. Titan, in particular, is modeled to have subsurface ocean pressures ≥ 150 MPa, which are above the highest pressures known to support life on Earth in natural ecosystems. Piezophiles are organisms that grow optimally at pressures higher than atmospheric (0.1 MPa) pressure and have specialized adaptations to the physical constraints of high-pressure environments - up to ~110 MPa at Challenger Deep, the highest pressure deep-sea habitat explored. While non-piezophilic microorganisms have been shown to survive short exposures at Titan relevant pressures, the mechanisms of their survival under such conditions remain largely unelucidated. To better understand these mechanisms, we have conducted a study of gene expression for Shewanella oneidensis MR-1 using a high-pressure experimental culturing system. MR-1 was subjected to short-term (15 min) and long-term (2 h) HHP of 158 MPa, a value consistent with pressures expected near the top of Titan's subsurface ocean. We show that MR-1 is metabolically active in situ at HHP and is capable of viable growth following 2 h exposure to 158 MPa, with minimal pressure training beforehand. We further find that MR-1 regulates 264 genes in response to short-term HHP, the majority of which are upregulated. Adaptations include upregulation of the genes argA, argB, argC, and argF involved in arginine biosynthesis and regulation of genes involved in membrane reconfiguration. MR-1 also utilizes stress response adaptations common to other environmental extremes such as genes encoding for the cold-shock protein CspG and antioxidant defense related genes. This study suggests Titan's ocean pressures may not limit life, as microorganisms could employ adaptations akin to those demonstrated by terrestrial organisms.
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Affiliation(s)
- Judy Malas
- Department of Earth and Environmental Sciences, University of Illinois Chicago, Chicago, IL, United States
| | - Daniel C. Russo
- Department of Earth and Environmental Sciences, University of Illinois Chicago, Chicago, IL, United States
| | - Olivier Bollengier
- Nantes Université, Univ Angers, Le Mans Université, CNRS, Laboratoire de Planétologie et Géosciences, LPG UMR 6112, Nantes, France
| | - Michael J. Malaska
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States
| | - Rosaly M. C. Lopes
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States
| | - Fabien Kenig
- Department of Earth and Environmental Sciences, University of Illinois Chicago, Chicago, IL, United States
| | - D'Arcy R. Meyer-Dombard
- Department of Earth and Environmental Sciences, University of Illinois Chicago, Chicago, IL, United States
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6
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Lainey V, Rambaux N, Tobie G, Cooper N, Zhang Q, Noyelles B, Baillié K. A recently formed ocean inside Saturn's moon Mimas. Nature 2024; 626:280-282. [PMID: 38326592 DOI: 10.1038/s41586-023-06975-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 12/14/2023] [Indexed: 02/09/2024]
Abstract
Moons potentially harbouring a global ocean are tending to become relatively common objects in the Solar System1. The presence of these long-lived global oceans is generally betrayed by surface modification owing to internal dynamics2. Hence, Mimas would be the most unlikely place to look for the presence of a global ocean3. Here, from detailed analysis of Mimas's orbital motion based on Cassini data, with a particular focus on Mimas's periapsis drift, we show that its heavily cratered icy shell hides a global ocean, at a depth of 20-30 kilometres. Eccentricity damping implies that the ocean is likely to be less than 25 million years old and still evolving. Our simulations show that the ocean-ice interface reached a depth of less than 30 kilometres only recently (less than 2-3 million years ago), a time span too short for signs of activity at Mimas's surface to have appeared.
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Affiliation(s)
- V Lainey
- IMCCE, Observatoire de Paris, PSL Research University, Sorbonne Université, CNRS, Université Lille, Paris, France.
| | - N Rambaux
- IMCCE, Observatoire de Paris, PSL Research University, Sorbonne Université, CNRS, Université Lille, Paris, France
| | - G Tobie
- LPG, UMR-CNRS 6112, Nantes Université, Nantes, France
| | - N Cooper
- Department of Physics and Astronomy, Queen Mary University of London, London, UK
| | - Q Zhang
- Department of Computer Science, Jinan University, Guangzhou, P. R. China
| | - B Noyelles
- Institut UTINAM, CNRS UMR 6213, Université de Franche-Comté, OSU THETA, BP 1615, Besançon, France
| | - K Baillié
- IMCCE, Observatoire de Paris, PSL Research University, Sorbonne Université, CNRS, Université Lille, Paris, France
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Rafiq KRB, Joseph A, Yokochi N, James P, von Jouanne A, Yokochi A. Modeling Development of a Diamagnetically Stabilized Magnetically Levitated Gravimeter. SENSORS (BASEL, SWITZERLAND) 2024; 24:350. [PMID: 38257443 PMCID: PMC11154353 DOI: 10.3390/s24020350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 12/25/2023] [Accepted: 01/04/2024] [Indexed: 01/24/2024]
Abstract
The aim of this work is to create a new type of gravimeter that can function effectively in the challenging conditions of space, specifically on the surfaces of planets and moons. The proposed device, called a diamagnetically stabilized magnetically levitated gravimeter (DSMLG), uses magnetic forces to balance a test mass against the force of gravity, allowing for accurate measurements. A diamagnetically stabilized levitation structure comprises a floating magnet, diamagnetic material, and a lifting magnet. The floating magnet levitates between two diamagnetic plates without the need for external energy input due to the interaction between the magnetic forces of the floating magnet and the stabilizing force of the diamagnetic material. This structure allows for stable levitation of the floating magnet without requiring additional energy. The goal is to design a gravimeter that is lightweight, requires minimal power, can withstand extreme temperatures and shocks, and has a low data rate. The authors envision this gravimeter being used on various robotic spacecraft, such as landers and rovers, to study the interiors of rocky and icy celestial bodies. This paper reports on the results of a finite element model analysis of the DSMLG and the strength of the resulting diamagnetic spring. The findings contribute to the understanding of the levitation characteristics of diamagnetically stabilized structures and provide valuable insights for their practical applications, including in the development of the proposed DSMLG.
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Affiliation(s)
- Kazi Rifat Bin Rafiq
- Department of Mechanical Engineering, Baylor University, Waco, TX 76798, USA; (K.R.B.R.); (A.J.); (N.Y.)
| | - Abigail Joseph
- Department of Mechanical Engineering, Baylor University, Waco, TX 76798, USA; (K.R.B.R.); (A.J.); (N.Y.)
| | - Naiya Yokochi
- Department of Mechanical Engineering, Baylor University, Waco, TX 76798, USA; (K.R.B.R.); (A.J.); (N.Y.)
| | - Peter James
- Department of Geosciences, Baylor University, Waco, TX 76706, USA;
| | - Annette von Jouanne
- Department of Electrical and Computer Engineering, Baylor University, Waco, TX 76706, USA;
| | - Alex Yokochi
- Department of Mechanical Engineering, Baylor University, Waco, TX 76798, USA; (K.R.B.R.); (A.J.); (N.Y.)
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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: 0.5] [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.
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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
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McClain CR, Bryant SR, Hanks G, Bowles MW. Extremophiles in Earth's Deep Seas: A View Toward Life in Exo-Oceans. ASTROBIOLOGY 2022; 22:1009-1028. [PMID: 35549348 DOI: 10.1089/ast.2021.0120] [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
Humanity's search for extraterrestrial life is a modern manifestation of the exploratory and curious nature that has led us through millennia of scientific discoveries. With the ongoing exploration of extraterrestrial bodies, the potential for discovery of extraterrestrial life has expanded. We may better inform this search through an understanding of how life persists and flourishes on Earth in a myriad of environmental extremes. A significant proportion of our knowledge of extremophiles on Earth comes from studies on deep ocean life. Here, we review and synthesize the range of environmental extremes observed in the deep sea, the life that persists in these extreme conditions, and the biological adaptations utilized by these remarkable life-forms. We also review confirmed and predicted extraterrestrial oceans in our solar system and propose deep-sea sites that may serve as planetary field analog environments. We show that the clever ingenuity of evolution under deep-sea conditions suggests that the plausibility of extraterrestrial life is much greater than previously thought.
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Affiliation(s)
- Craig R McClain
- Louisiana Universities Marine Consortium, Chauvin, Louisiana, USA
- Department of Biology, University of Louisiana at Lafayette, Lafayette, Louisiana, USA
| | - S River Bryant
- Louisiana Universities Marine Consortium, Chauvin, Louisiana, USA
- Department of Biology, University of Louisiana at Lafayette, Lafayette, Louisiana, USA
| | - Granger Hanks
- Louisiana Universities Marine Consortium, Chauvin, Louisiana, USA
- Department of Biology, University of Louisiana at Lafayette, Lafayette, Louisiana, USA
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10
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Rivera-Valentín EG, Filiberto J, Lynch KL, Mamajanov I, Lyons TW, Schulte M, Méndez A. Introduction-First Billion Years: Habitability. ASTROBIOLOGY 2021; 21:893-905. [PMID: 34406807 PMCID: PMC8403211 DOI: 10.1089/ast.2020.2314] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 12/22/2020] [Indexed: 06/13/2023]
Abstract
The physical processes active during the first billion years (FBY) of Earth's history, such as accretion, differentiation, and impact cratering, provide constraints on the initial conditions that were conducive to the formation and establishment of life on Earth. This motivated the Lunar and Planetary Institute's FBY topical initiative, which was a four-part conference series intended to look at each of these physical processes to study the basic structure and composition of our Solar System that was set during the FBY. The FBY Habitability conference, held in September 2019, was the last in this series and was intended to synthesize the initiative; specifically, to further our understanding of the origins of life, planetary and environmental habitability, and the search for life beyond Earth. The conference included discussions of planetary habitability and the potential emergence of life on bodies within our Solar System, as well as extrasolar systems by applying our knowledge of the Solar System's FBY, and in particular Earth's early history. To introduce this Special Collection, which resulted from work discussed at the conference, we provide a review of the main themes and a synopsis of the FBY Habitability conference.
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Affiliation(s)
| | - Justin Filiberto
- Lunar and Planetary Institute, Universities Space Research Association, Houston, Texas, USA
| | - Kennda L. Lynch
- Lunar and Planetary Institute, Universities Space Research Association, Houston, Texas, USA
| | - Irena Mamajanov
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan
| | - Timothy W. Lyons
- Department of Earth and Planetary Sciences, University of California Riverside, Riverside, California, USA
| | - Mitch Schulte
- Planetary Science Division, NASA Headquarters, Washington, District of Columbia, USA
| | - Abel Méndez
- Planetary Habitability Laboratory, University of Puerto Rico Arecibo, Arecibo, Puerto Rico
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11
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Le Tiec A, Casals M. Spinning Black Holes Fall in Love. PHYSICAL REVIEW LETTERS 2021; 126:131102. [PMID: 33861128 DOI: 10.1103/physrevlett.126.131102] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 09/18/2020] [Accepted: 02/16/2021] [Indexed: 06/12/2023]
Abstract
The open question of whether a black hole can become tidally deformed by an external gravitational field has profound implications for fundamental physics, astrophysics, and gravitational-wave astronomy. Love tensors characterize the tidal deformability of compact objects such as astrophysical (Kerr) black holes under an external static tidal field. We prove that all Love tensors vanish identically for a Kerr black hole in the nonspinning limit or for an axisymmetric tidal perturbation. In contrast to this result, we show that Love tensors are generically nonzero for a spinning black hole. Specifically, to linear order in the Kerr black hole spin and the weak perturbing tidal field, we compute in closed form the Love tensors that couple the mass-type and current-type quadrupole moments to the electric-type and magnetic-type quadrupolar tidal fields. For a dimensionless spin ∼0.1, the nonvanishing quadrupolar Love tensors are ∼2×10^{-3}, thus showing that black holes are particularly "rigid" compact objects.
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Affiliation(s)
- Alexandre Le Tiec
- Laboratoire Univers et Théories, Observatoire de Paris, CNRS, Université PSL, Université de Paris, 92190 Meudon, France
- Centro Brasileiro de Pesquisas Físicas (CBPF), Rio de Janeiro, CEP 22290-180, Brazil
| | - Marc Casals
- Centro Brasileiro de Pesquisas Físicas (CBPF), Rio de Janeiro, CEP 22290-180, Brazil
- School of Mathematics and Statistics, University College Dublin, Belfield, Dublin 4, Ireland
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12
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Aguzzi J, Flexas MM, Flögel S, Lo Iacono C, Tangherlini M, Costa C, Marini S, Bahamon N, Martini S, Fanelli E, Danovaro R, Stefanni S, Thomsen L, Riccobene G, Hildebrandt M, Masmitja I, Del Rio J, Clark EB, Branch A, Weiss P, Klesh AT, Schodlok MP. Exo-Ocean Exploration with Deep-Sea Sensor and Platform Technologies. ASTROBIOLOGY 2020; 20:897-915. [PMID: 32267735 DOI: 10.1089/ast.2019.2129] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
One of Saturn's largest moons, Enceladus, possesses a vast extraterrestrial ocean (i.e., exo-ocean) that is increasingly becoming the hotspot of future research initiatives dedicated to the exploration of putative life. Here, a new bio-exploration concept design for Enceladus' exo-ocean is proposed, focusing on the potential presence of organisms across a wide range of sizes (i.e., from uni- to multicellular and animal-like), according to state-of-the-art sensor and robotic platform technologies used in terrestrial deep-sea research. In particular, we focus on combined direct and indirect life-detection capabilities, based on optoacoustic imaging and passive acoustics, as well as molecular approaches. Such biologically oriented sampling can be accompanied by concomitant geochemical and oceanographic measurements to provide data relevant to exo-ocean exploration and understanding. Finally, we describe how this multidisciplinary monitoring approach is currently enabled in terrestrial oceans through cabled (fixed) observatories and their related mobile multiparametric platforms (i.e., Autonomous Underwater and Remotely Operated Vehicles, as well as crawlers, rovers, and biomimetic robots) and how their modified design can be used for exo-ocean exploration.
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Affiliation(s)
- J Aguzzi
- Instituto de Ciencias del Mar (ICM-CSIC), Barcelona, Spain
- Stazione Zoologica Anton Dohrn, Naples, Italy
| | - M M Flexas
- California Institute of Technology, Pasadena, California, USA
| | - S Flögel
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - C Lo Iacono
- Instituto de Ciencias del Mar (ICM-CSIC), Barcelona, Spain
- National Oceanographic Center (NOC), University of Southampton, Southampton, United Kingdom
| | | | - C Costa
- Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria (CREA)-Centro di ricerca Ingegneria e Trasformazioni agroalimentari - Monterotondo, Rome, Italy
| | - S Marini
- Stazione Zoologica Anton Dohrn, Naples, Italy
- National Research Council of Italy (CNR), Institute of Marine Sciences, La Spezia, Italy
| | - N Bahamon
- Instituto de Ciencias del Mar (ICM-CSIC), Barcelona, Spain
- Centro de Estudios Avanzados de Blanes (CEAB-CSIC), Blanes, Spain
| | - S Martini
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, Villefranche-sur-mer, France
| | - E Fanelli
- Stazione Zoologica Anton Dohrn, Naples, Italy
- Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, Italy
| | - R Danovaro
- Stazione Zoologica Anton Dohrn, Naples, Italy
- Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, Italy
| | - S Stefanni
- Stazione Zoologica Anton Dohrn, Naples, Italy
| | | | - G Riccobene
- Istituto Nazionale di Fisica Nucleare (INFN), Laboratori Nazionali del Sud, Catania, Italy
| | - M Hildebrandt
- German Research Center for Artificial Intelligence (DFKI), Bremen, Germany
| | - I Masmitja
- SARTI, Universitat Politècnica de Catalunya (UPC), Barcelona, Spain
| | - J Del Rio
- SARTI, Universitat Politècnica de Catalunya (UPC), Barcelona, Spain
| | - E B Clark
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - A Branch
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | | | - A T Klesh
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - M P Schodlok
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
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13
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Longo A, Damer B. Factoring Origin of Life Hypotheses into the Search for Life in the Solar System and Beyond. Life (Basel) 2020; 10:E52. [PMID: 32349245 PMCID: PMC7281141 DOI: 10.3390/life10050052] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 04/14/2020] [Accepted: 04/22/2020] [Indexed: 01/13/2023] Open
Abstract
Two widely-cited alternative hypotheses propose geological localities and biochemical mechanisms for life's origins. The first states that chemical energy available in submarine hydrothermal vents supported the formation of organic compounds and initiated primitive metabolic pathways which became incorporated in the earliest cells; the second proposes that protocells self-assembled from exogenous and geothermally-delivered monomers in freshwater hot springs. These alternative hypotheses are relevant to the fossil record of early life on Earth, and can be factored into the search for life elsewhere in the Solar System. This review summarizes the evidence supporting and challenging these hypotheses, and considers their implications for the search for life on various habitable worlds. It will discuss the relative probability that life could have emerged in environments on early Mars, on the icy moons of Jupiter and Saturn, and also the degree to which prebiotic chemistry could have advanced on Titan. These environments will be compared to ancient and modern terrestrial analogs to assess their habitability and biopreservation potential. Origins of life approaches can guide the biosignature detection strategies of the next generation of planetary science missions, which could in turn advance one or both of the leading alternative abiogenesis hypotheses.
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Affiliation(s)
- Alex Longo
- National Aeronautics and Space Administration Headquarters, Washington, DC 20546, USA
- Department of Geology, The University of North Carolina, Chapel Hill, NC 27599, USA
| | - Bruce Damer
- Department of Biomolecular Engineering, University of California, Santa Cruz, CA 95064, USA or
- Digital Space Research, Boulder Creek, CA 95006, USA
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14
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Abstract
The Cassini-Huygens mission to Saturn provided a close-up study of the gas giant planet, as well as its rings, moons, and magnetosphere. The Cassini spacecraft arrived at Saturn in 2004, dropped the Huygens probe to study the atmosphere and surface of Saturn's planet-sized moon Titan, and orbited Saturn for the next 13 years. In 2017, when it was running low on fuel, Cassini was intentionally vaporized in Saturn's atmosphere to protect the ocean moons, Enceladus and Titan, where it had discovered habitats potentially suitable for life. Mission findings include Enceladus' south polar geysers, the source of Saturn's E ring; Titan's methane cycle, including rain that creates hydrocarbon lakes; dynamic rings containing ice, silicates, and organics; and Saturn's differential rotation. This Review discusses highlights of Cassini's investigations, including the mission's final year.
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Affiliation(s)
- Linda Spilker
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
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15
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Vance SD, Melwani Daswani M. Serpentinite and the search for life beyond Earth. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2020; 378:20180421. [PMID: 31902342 DOI: 10.1098/rsta.2018.0421] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/27/2019] [Indexed: 06/10/2023]
Abstract
Hydrogen from serpentinization is a source of chemical energy for some life forms on Earth. It is a potential fuel for life in the subsurface of Mars and in the icy ocean worlds in the outer solar system. Serpentinization is also implicated in life's origin. Planetary exploration offers a way to investigate such theories by characterizing and ultimately searching for life in geochemical settings that no longer exist on Earth. At present, much of the current context of serpentinization on other worlds relies on inference from modelling and studies on Earth. While there is evidence from orbital spectral imaging and martian meteorites that serpentinization has occurred on Mars, the extent and duration of that activity has not been constrained. Similarly, ongoing serpentinization might explain hydrogen found in the ocean of Saturn's tiny moon Enceladus, but this raises questions about how long such activity has persisted. Titan's hydrocarbon-rich atmosphere may derive from ancient or present-day serpentinization at the bottom of its ocean. In Europa, volcanism or serpentinization may provide hydrogen as a redox couple to oxygen generated at the moon's surface. We assess the potential extent of serpentinization in the solar system's wet and rocky worlds, assuming that microfracturing from thermal expansion anisotropy sets an upper limit on the percolation depth of surface water into the rocky interiors. In this bulk geophysical model, planetary cooling from radiogenic decay implies the infiltration of water to greater depths through time, continuing to the present. The serpentinization of this newly exposed rock is assessed as a significant source of global hydrogen. Comparing the computed hydrogen and surface-generated oxygen delivered to Europa's ocean reveals redox fluxes similar to Earth's. Planned robotic exploration missions to other worlds can aid in understanding the planetary context of serpentinization, testing the predictions herein. This article is part of a discussion meeting issue 'Serpentinite in the Earth System'.
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Affiliation(s)
- S D Vance
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8001, USA
| | - M Melwani Daswani
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8001, USA
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16
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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: 13] [Impact Index Per Article: 2.6] [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.
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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
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17
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Martin KP, MacKenzie SM, Barnes JW, Ytreberg FM. Protein Stability in Titan's Subsurface Water Ocean. ASTROBIOLOGY 2020; 20:190-198. [PMID: 31730377 PMCID: PMC7041334 DOI: 10.1089/ast.2018.1972] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 10/08/2019] [Indexed: 06/10/2023]
Abstract
Models of Titan predict that there is a subsurface ocean of water and ammonia under a layer of ice. Such an ocean would be important in the search for extraterrestrial life since it provides a potentially habitable environment. To evaluate how Earth-based proteins would behave in Titan's subsurface ocean environment, we used molecular dynamics simulations to calculate the properties of proteins with the most common secondary structure types (alpha helix and beta sheet) in both Earth and Titan-like conditions. The Titan environment was simulated by using a temperature of 300 K, a pressure of 1000 bar, and a eutectic mixture of water and ammonia. We analyzed protein compactness, flexibility, and backbone dihedral distributions to identify differences between the two environments. Secondary structures in the Titan environment were found to be less long-lasting, less flexible, and had small differences in backbone dihedral preferences (e.g., in one instance a pi helix formed). These environment-driven differences could lead to changes in how these proteins interact with other biomolecules and therefore changes in how evolution would potentially shape proteins to function in subsurface ocean environments.
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Affiliation(s)
- Kyle P. Martin
- Department of Physics, University of Idaho, Moscow, Idaho
- Institute for Modeling Collaboration and Innovation, University of Idaho, Moscow, Idaho
| | | | | | - F. Marty Ytreberg
- Department of Physics, University of Idaho, Moscow, Idaho
- Institute for Modeling Collaboration and Innovation, University of Idaho, Moscow, Idaho
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18
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The Equation of State of MH-III: A Possible Deep CH4 Reservoir in Titan, Super-Titan Exoplanets, and Moons. ACTA ACUST UNITED AC 2019. [DOI: 10.3847/1538-4357/ab2f76] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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19
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Dual Frequency Orbiter-Radar System for the Observation of Seas and Tides on Titan: Extraterrestrial Oceanography from Satellite. REMOTE SENSING 2019. [DOI: 10.3390/rs11161898] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Saturn’s largest moon, Titan, is believed to have a ~100 km thick ice shell above a global ocean of liquid water. Organic materials, including liquid hydrocarbon lakes and seas in its polar terrain, cover Titan’s surface, which makes it a world of two oceans. The RADAR instrument on board Cassini, was able to probe lakes and seas during few dedicated altimetric observations, revealing its capability to work as a sounder. Herein, we describe the design of, and scientific motivation for, a dual frequency X/Ka-band radar system that is able to investigate Titan’s subsurface liquid water ocean, as well as the depth and composition of its surface liquid hydrocarbon basins. The proposed system, which could take advantage of the telecommunications dish, can operate as a sounder, as Synthetic Aperture Radar (SAR) able to map the surface at tens meters of scale resolution, and when data are acquired from close-adjacent orbits, as a repeat-pass SAR interferometer (InSAR). The instrument, which is based on the architecture of the Cassini RADAR, can also characterize Titan’s interior by using geophysical measurements of the tidal amplitude to derive high accuracy estimates of the Love number h2 from a 1500 km circular orbit.
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20
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Martens HR, Rivera L, Simons M. LoadDef: A Python-Based Toolkit to Model Elastic Deformation Caused by Surface Mass Loading on Spherically Symmetric Bodies. EARTH AND SPACE SCIENCE (HOBOKEN, N.J.) 2019; 6:311-323. [PMID: 31008150 PMCID: PMC6472329 DOI: 10.1029/2018ea000462] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 01/02/2019] [Accepted: 01/18/2019] [Indexed: 06/09/2023]
Abstract
Temporal variations of surface masses, such as the hydrosphere and atmosphere of the Earth, load the surfaces of planetary bodies causing temporal variations in deformation. Surface shear forces and gravitational fields also drive ongoing planetary deformation. Characterizing the spatiotemporal patterns of planetary deformation can constrain allowable models for the interior structure of a planetary body as well as for the distribution of surface and body forces. Pertinent applications include hydrology, glaciology, geodynamics, atmospheric science, and climatology. To address the diversity of emerging applications, we introduce a software suite called LoadDef that provides a collection of modular functions for modeling planetary deformation within a self-consistent, Python-based computational framework. Key features of LoadDef include computation of real-valued potential, load, and shear Love numbers for self-gravitating and spherically symmetric planetary models; computation of Love-number partial derivatives with respect to planetary density and elastic structure; computation of displacement, gravity, tilt, and strain load Green's functions; and computation of three-component surface displacements induced by surface mass loading. At a most basic level, only a planetary-structure model and a mass-load model must be supplied as input to LoadDef to utilize all the main features of the software. The end-to-end forward-modeling capabilities for mass-loading applications lay the foundation for sensitivity studies and geodetic tomography. LoadDef results have been validated with Global Navigation Satellite System observations and verified against independent software and published results. As a case study, we use LoadDef to predict the solid Earth's elastic response to ocean tidal loading across the western United States.
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Affiliation(s)
| | - Luis Rivera
- Institut de Physique du Globe de Strasbourg, UMR 7516 CNRS, Université de StrasbourgStrasbourgFrance
| | - Mark Simons
- Seismological Laboratory, Division of Geological and Planetary SciencesCalifornia Institute of TechnologyPasadenaCAUSA
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21
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Iess L, Militzer B, Kaspi Y, Nicholson P, Durante D, Racioppa P, Anabtawi A, Galanti E, Hubbard W, Mariani MJ, Tortora P, Wahl S, Zannoni M. Measurement and implications of Saturn’s gravity field and ring mass. Science 2019; 364:science.aat2965. [DOI: 10.1126/science.aat2965] [Citation(s) in RCA: 104] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 12/19/2018] [Indexed: 11/03/2022]
Abstract
The interior structure of Saturn, the depth of its winds, and the mass and age of its rings constrain its formation and evolution. In the final phase of the Cassini mission, the spacecraft dived between the planet and its innermost ring, at altitudes of 2600 to 3900 kilometers above the cloud tops. During six of these crossings, a radio link with Earth was monitored to determine the gravitational field of the planet and the mass of its rings. We find that Saturn’s gravity deviates from theoretical expectations and requires differential rotation of the atmosphere extending to a depth of at least 9000 kilometers. The total mass of the rings is (1.54 ± 0.49) × 1019 kilograms (0.41 ± 0.13 times that of the moon Mimas), indicating that the rings may have formed 107 to 108 years ago.
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Affiliation(s)
- L. Iess
- Department of Mechanical and Aerospace Engineering, Sapienza Università di Roma, Rome 00184, Italy
| | - B. Militzer
- Department of Astronomy, University of California, Berkeley, Berkeley, CA 94720, USA
- Department of Earth and Planetary Science, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Y. Kaspi
- Department of Earth and Planetary Sciences Weizmann Institute of Science, Rehovot 76100, Israel
| | - P. Nicholson
- Department of Astronomy, Cornell University, Ithaca, NY 14853, USA
| | - D. Durante
- Department of Mechanical and Aerospace Engineering, Sapienza Università di Roma, Rome 00184, Italy
| | - P. Racioppa
- Department of Mechanical and Aerospace Engineering, Sapienza Università di Roma, Rome 00184, Italy
| | - A. Anabtawi
- Jet Propulsion Laboratory–Caltech, Pasadena, CA 91109, USA
| | - E. Galanti
- Department of Earth and Planetary Sciences Weizmann Institute of Science, Rehovot 76100, Israel
| | - W. Hubbard
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA
| | - M. J. Mariani
- Department of Mechanical and Aerospace Engineering, Sapienza Università di Roma, Rome 00184, Italy
| | - P. Tortora
- Department of Industrial Engineering, Università di Bologna, Forlì 47100, Italy
| | - S. Wahl
- Department of Earth and Planetary Science, University of California, Berkeley, Berkeley, CA 94720, USA
| | - M. Zannoni
- Department of Industrial Engineering, Università di Bologna, Forlì 47100, Italy
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22
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Thompson SP, Kennedy H, Day SJ, Baker AR, Butler BM, Safi E, Kelly J, Male A, Potter J, Cobb T, Murray CA, Tang CC, Evans A, Mercado R. A slow-cooling-rate in situ cell for long-duration studies of mineral precipitation in cold aqueous environments on Earth and other planetary bodies. J Appl Crystallogr 2018; 51:1197-1210. [PMID: 30147638 PMCID: PMC6100201 DOI: 10.1107/s1600576718008816] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 06/15/2018] [Indexed: 11/11/2022] Open
Abstract
Liquid oceans and ice caps, along with ice crusts, have long been considered defining features of the Earth, but space missions and observations have shown that they are in fact common features among many of the solar system's outer planets and their satellites. Interactions with rock-forming materials have produced saline oceans not dissimilar in many respects to those on Earth, where mineral precipitation within frozen seawater plays a significant role in both determining global properties and regulating the environment in which a complex ecosystem of extremophiles exists. Since water is considered an essential ingredient for life, the presence of oceans and ice on other solar system bodies is of great astrobiological interest. However, the details surrounding mineral precipitation in freezing environments are still poorly constrained, owing to the difficulties of sampling and ex situ preservation for laboratory analysis, meaning that predictive models have limited empirical underpinnings. To address this, the design and performance characterization of a transmission-geometry sample cell for use in long-duration synchrotron X-ray powder diffraction studies of in situ mineral precipitation from aqueous ice-brine systems are presented. The cell is capable of very slow cooling rates (e.g. 0.3°C per day or less), and its performance is demonstrated with the results from a year-long study of the precipitation of the hydrated magnesium sulfate phase meridianiite (MgSO4·11H2O) from the MgSO4-H2O system. Evidence from the Mars Rover mission suggests that this hydrated phase is widespread on the present-day surface of Mars. However, as well as the predicted hexagonal ice and meridianiite phases, an additional hydrated sulfate phase and a disordered phase are observed.
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Affiliation(s)
- Stephen P. Thompson
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Hilary Kennedy
- School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey LL59 5AB, UK
| | - Sarah J. Day
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Annabelle R. Baker
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Benjamin M. Butler
- Environmental and Biochemical Sciences, The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, UK
| | - Emmal Safi
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
- Astrophysics Group, Lennard-Jones Laboratories, Keele University, Keele, Staffordshire ST5 5BG, UK
| | - Jon Kelly
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Andrew Male
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Jonathan Potter
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Tom Cobb
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Claire A. Murray
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Chiu C. Tang
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Aneurin Evans
- Astrophysics Group, Lennard-Jones Laboratories, Keele University, Keele, Staffordshire ST5 5BG, UK
| | - Ronaldo Mercado
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
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23
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Neish CD, Lorenz RD, Turtle EP, Barnes JW, Trainer MG, Stiles B, Kirk R, Hibbitts CA, Malaska MJ. Strategies for Detecting Biological Molecules on Titan. ASTROBIOLOGY 2018; 18:571-585. [PMID: 29718687 DOI: 10.1089/ast.2017.1758] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Saturn's moon Titan has all the ingredients needed to produce "life as we know it." When exposed to liquid water, organic molecules analogous to those found on Titan produce a range of biomolecules such as amino acids. Titan thus provides a natural laboratory for studying the products of prebiotic chemistry. In this work, we examine the ideal locales to search for evidence of, or progression toward, life on Titan. We determine that the best sites to identify biological molecules are deposits of impact melt on the floors of large, fresh impact craters, specifically Sinlap, Selk, and Menrva craters. We find that it is not possible to identify biomolecules on Titan through remote sensing, but rather through in situ measurements capable of identifying a wide range of biological molecules. Given the nonuniformity of impact melt exposures on the floor of a weathered impact crater, the ideal lander would be capable of precision targeting. This would allow it to identify the locations of fresh impact melt deposits, and/or sites where the melt deposits have been exposed through erosion or mass wasting. Determining the extent of prebiotic chemistry within these melt deposits would help us to understand how life could originate on a world very different from Earth. Key Words: Titan-Prebiotic chemistry-Solar system exploration-Impact processes-Volcanism. Astrobiology 18, 571-585.
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Affiliation(s)
- Catherine D Neish
- 1 Department of Earth Sciences, The University of Western Ontario , London, Canada
| | - Ralph D Lorenz
- 2 The Johns Hopkins Applied Physics Laboratory , Laurel, Maryland
| | | | - Jason W Barnes
- 3 Department of Physics, University of Idaho , Moscow, Idaho
| | | | - Bryan Stiles
- 5 Jet Propulsion Laboratory, California Institute of Technology , Pasadena, California
| | - Randolph Kirk
- 6 United States Geological Survey, Astrogeology Science Center , Flagstaff, Arizona
| | | | - Michael J Malaska
- 5 Jet Propulsion Laboratory, California Institute of Technology , Pasadena, California
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24
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Vance SD, Kedar S, Panning MP, Stähler SC, Bills BG, Lorenz RD, Huang HH, Pike WT, Castillo JC, Lognonné P, Tsai VC, Rhoden AR. Vital Signs: Seismology of Icy Ocean Worlds. ASTROBIOLOGY 2018; 18:37-53. [PMID: 29345986 DOI: 10.1089/ast.2016.1612] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Ice-covered ocean worlds possess diverse energy sources and associated mechanisms that are capable of driving significant seismic activity, but to date no measurements of their seismic activity have been obtained. Such investigations could reveal the transport properties and radial structures, with possibilities for locating and characterizing trapped liquids that may host life and yielding critical constraints on redox fluxes and thus on habitability. Modeling efforts have examined seismic sources from tectonic fracturing and impacts. Here, we describe other possible seismic sources, their associations with science questions constraining habitability, and the feasibility of implementing such investigations. We argue, by analogy with the Moon, that detectable seismic activity should occur frequently on tidally flexed ocean worlds. Their ices fracture more easily than rocks and dissipate more tidal energy than the <1 GW of the Moon and Mars. Icy ocean worlds also should create less thermal noise due to their greater distance and consequently smaller diurnal temperature variations. They also lack substantial atmospheres (except in the case of Titan) that would create additional noise. Thus, seismic experiments could be less complex and less susceptible to noise than prior or planned planetary seismology investigations of the Moon or Mars. Key Words: Seismology-Redox-Ocean worlds-Europa-Ice-Hydrothermal. Astrobiology 18, 37-53.
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Affiliation(s)
- Steven D Vance
- 1 Jet Propulsion Laboratory, California Institute of Technology , Pasadena, California, USA
| | - Sharon Kedar
- 1 Jet Propulsion Laboratory, California Institute of Technology , Pasadena, California, USA
| | - Mark P Panning
- 1 Jet Propulsion Laboratory, California Institute of Technology , Pasadena, California, USA
| | - Simon C Stähler
- 2 Institute of Geophysics , ETH Zürich, Zürich, Switzerland
- 3 Leibniz-Institute for Baltic Sea Research (IOW) , Rostock, Germany
| | - Bruce G Bills
- 1 Jet Propulsion Laboratory, California Institute of Technology , Pasadena, California, USA
| | - Ralph D Lorenz
- 4 Johns Hopkins Applied Physics Laboratory , Laurel, Maryland, USA
| | - Hsin-Hua Huang
- 5 Institute of Earth Sciences , Academia Sinica, Taipei, Taiwan
- 6 Seismological Laboratory, California Institute of Technology , Pasadena, California, USA
| | - W T Pike
- 7 Optical and Semiconductor Devices Group, Department of Electrical and Electronic Engineering, Imperial College , London, UK
| | - Julie C Castillo
- 1 Jet Propulsion Laboratory, California Institute of Technology , Pasadena, California, USA
| | - Philippe Lognonné
- 8 Univ Paris Diderot-Sorbonne Paris Cité, Institut de Physique du Globe de Paris , Paris, France
| | - Victor C Tsai
- 6 Seismological Laboratory, California Institute of Technology , Pasadena, California, USA
| | - Alyssa R Rhoden
- 9 School of Earth and Space Exploration, Arizona State University , Tempe, Arizona, USA
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25
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Black BA, Perron JT, Hemingway D, Bailey E, Nimmo F, Zebker H. Global drainage patterns and the origins of topographic relief on Earth, Mars, and Titan. Science 2017; 356:727-731. [PMID: 28522528 DOI: 10.1126/science.aag0171] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 04/06/2017] [Indexed: 11/02/2022]
Abstract
Rivers have eroded the topography of Mars, Titan, and Earth, creating diverse landscapes. However, the dominant processes that generated topography on Titan (and to some extent on early Mars) are not well known. We analyzed drainage patterns on all three bodies and found that large drainages, which record interactions between deformation and erosional modification, conform much better to long-wavelength topography on Titan and Mars than on Earth. We use a numerical landscape evolution model to demonstrate that short-wavelength deformation causes drainage directions to diverge from long-wavelength topography, as observed on Earth. We attribute the observed differences to ancient long-wavelength topography on Mars, recent or ongoing generation of long-wavelength relief on Titan, and the creation of short-wavelength relief by plate tectonics on Earth.
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Affiliation(s)
- Benjamin A Black
- Department of Earth and Atmospheric Science, City College of New York, City University of New York, New York, NY, USA. .,Earth and Environmental Science, The Graduate Center, City University of New York, New York, NY, USA
| | - J Taylor Perron
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Douglas Hemingway
- Department of Earth and Planetary Science, University of California, Berkeley, Berkeley, CA, USA.
| | - Elizabeth Bailey
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
| | - Francis Nimmo
- Department of Earth and Planetary Sciences, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Howard Zebker
- Department of Geophysics, School of Earth Sciences, Stanford University, Stanford, CA, USA
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26
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Domagal-Goldman SD, Wright KE, Adamala K, Arina de la Rubia L, Bond J, Dartnell LR, Goldman AD, Lynch K, Naud ME, Paulino-Lima IG, Singer K, Walther-Antonio M, Abrevaya XC, Anderson R, Arney G, Atri D, Azúa-Bustos A, Bowman JS, Brazelton WJ, Brennecka GA, Carns R, Chopra A, Colangelo-Lillis J, Crockett CJ, DeMarines J, Frank EA, Frantz C, de la Fuente E, Galante D, Glass J, Gleeson D, Glein CR, Goldblatt C, Horak R, Horodyskyj L, Kaçar B, Kereszturi A, Knowles E, Mayeur P, McGlynn S, Miguel Y, Montgomery M, Neish C, Noack L, Rugheimer S, Stüeken EE, Tamez-Hidalgo P, Imari Walker S, Wong T. The Astrobiology Primer v2.0. ASTROBIOLOGY 2016; 16:561-653. [PMID: 27532777 PMCID: PMC5008114 DOI: 10.1089/ast.2015.1460] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 06/06/2016] [Indexed: 05/09/2023]
Affiliation(s)
- Shawn D Domagal-Goldman
- 1 NASA Goddard Space Flight Center , Greenbelt, Maryland, USA
- 2 Virtual Planetary Laboratory , Seattle, Washington, USA
| | - Katherine E Wright
- 3 University of Colorado at Boulder , Colorado, USA
- 4 Present address: UK Space Agency, UK
| | - Katarzyna Adamala
- 5 Department of Genetics, Cell Biology and Development, University of Minnesota , Minneapolis, Minnesota, USA
| | | | - Jade Bond
- 7 Department of Physics, University of New South Wales , Sydney, Australia
| | | | | | - Kennda Lynch
- 10 Division of Biological Sciences, University of Montana , Missoula, Montana, USA
| | - Marie-Eve Naud
- 11 Institute for research on exoplanets (iREx) , Université de Montréal, Montréal, Canada
| | - Ivan G Paulino-Lima
- 12 Universities Space Research Association , Mountain View, California, USA
- 13 Blue Marble Space Institute of Science , Seattle, Washington, USA
| | - Kelsi Singer
- 14 Southwest Research Institute , Boulder, Colorado, USA
| | | | - Ximena C Abrevaya
- 16 Instituto de Astronomía y Física del Espacio (IAFE) , UBA-CONICET, Ciudad Autónoma de Buenos Aires, Argentina
| | - Rika Anderson
- 17 Department of Biology, Carleton College , Northfield, Minnesota, USA
| | - Giada Arney
- 18 University of Washington Astronomy Department and Astrobiology Program , Seattle, Washington, USA
| | - Dimitra Atri
- 13 Blue Marble Space Institute of Science , Seattle, Washington, USA
| | | | - Jeff S Bowman
- 19 Lamont-Doherty Earth Observatory, Columbia University , Palisades, New York, USA
| | | | | | - Regina Carns
- 22 Polar Science Center, Applied Physics Laboratory, University of Washington , Seattle, Washington, USA
| | - Aditya Chopra
- 23 Planetary Science Institute, Research School of Earth Sciences, Research School of Astronomy and Astrophysics, The Australian National University , Canberra, Australia
| | - Jesse Colangelo-Lillis
- 24 Earth and Planetary Science, McGill University , and the McGill Space Institute, Montréal, Canada
| | | | - Julia DeMarines
- 13 Blue Marble Space Institute of Science , Seattle, Washington, USA
| | | | - Carie Frantz
- 27 Department of Geosciences, Weber State University , Ogden, Utah, USA
| | - Eduardo de la Fuente
- 28 IAM-Departamento de Fisica, CUCEI , Universidad de Guadalajara, Guadalajara, México
| | - Douglas Galante
- 29 Brazilian Synchrotron Light Laboratory , Campinas, Brazil
| | - Jennifer Glass
- 30 School of Earth and Atmospheric Sciences, Georgia Institute of Technology , Atlanta, Georgia , USA
| | | | | | - Colin Goldblatt
- 33 School of Earth and Ocean Sciences, University of Victoria , Victoria, Canada
| | - Rachel Horak
- 34 American Society for Microbiology , Washington, DC, USA
| | | | - Betül Kaçar
- 36 Harvard University , Organismic and Evolutionary Biology, Cambridge, Massachusetts, USA
| | - Akos Kereszturi
- 37 Research Centre for Astronomy and Earth Sciences , Hungarian Academy of Sciences, Budapest, Hungary
| | - Emily Knowles
- 38 Johnson & Wales University , Denver, Colorado, USA
| | - Paul Mayeur
- 39 Rensselaer Polytechnic Institute , Troy, New York, USA
| | - Shawn McGlynn
- 40 Earth Life Science Institute, Tokyo Institute of Technology , Tokyo, Japan
| | - Yamila Miguel
- 41 Laboratoire Lagrange, UMR 7293, Université Nice Sophia Antipolis , CNRS, Observatoire de la Côte d'Azur, Nice, France
| | | | - Catherine Neish
- 43 Department of Earth Sciences, The University of Western Ontario , London, Canada
| | - Lena Noack
- 44 Royal Observatory of Belgium , Brussels, Belgium
| | - Sarah Rugheimer
- 45 Department of Astronomy, Harvard University , Cambridge, Massachusetts, USA
- 46 University of St. Andrews , St. Andrews, UK
| | - Eva E Stüeken
- 47 University of Washington , Seattle, Washington, USA
- 48 University of California , Riverside, California, USA
| | | | - Sara Imari Walker
- 13 Blue Marble Space Institute of Science , Seattle, Washington, USA
- 50 School of Earth and Space Exploration and Beyond Center for Fundamental Concepts in Science, Arizona State University , Tempe, Arizona, USA
| | - Teresa Wong
- 51 Department of Earth and Planetary Sciences, Washington University in St. Louis , St. Louis, Missouri, USA
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27
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Hinderer T, Taracchini A, Foucart F, Buonanno A, Steinhoff J, Duez M, Kidder LE, Pfeiffer HP, Scheel MA, Szilagyi B, Hotokezaka K, Kyutoku K, Shibata M, Carpenter CW. Effects of Neutron-Star Dynamic Tides on Gravitational Waveforms within the Effective-One-Body Approach. PHYSICAL REVIEW LETTERS 2016; 116:181101. [PMID: 27203312 DOI: 10.1103/physrevlett.116.181101] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Indexed: 05/27/2023]
Abstract
Extracting the unique information on ultradense nuclear matter from the gravitational waves emitted by merging neutron-star binaries requires robust theoretical models of the signal. We develop a novel effective-one-body waveform model that includes, for the first time, dynamic (instead of only adiabatic) tides of the neutron star as well as the merger signal for neutron-star-black-hole binaries. We demonstrate the importance of the dynamic tides by comparing our model against new numerical-relativity simulations of nonspinning neutron-star-black-hole binaries spanning more than 24 gravitational-wave cycles, and to other existing numerical simulations for double neutron-star systems. Furthermore, we derive an effective description that makes explicit the dependence of matter effects on two key parameters: tidal deformability and fundamental oscillation frequency.
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Affiliation(s)
- Tanja Hinderer
- Department of Physics, University of Maryland, College Park, Maryland 20742, USA
- Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Mühlenberg 1, Potsdam-Golm 14476, Germany
| | - Andrea Taracchini
- Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Mühlenberg 1, Potsdam-Golm 14476, Germany
| | - Francois Foucart
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - Alessandra Buonanno
- Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Mühlenberg 1, Potsdam-Golm 14476, Germany
| | - Jan Steinhoff
- Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Mühlenberg 1, Potsdam-Golm 14476, Germany
- Centro Multidisciplinar de Astrofísica, Departamento de Física, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais 1, 1049-001 Lisboa, Portugal
| | - Matthew Duez
- Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164, USA
| | - Lawrence E Kidder
- Cornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca, New York 14853, USA
| | - Harald P Pfeiffer
- Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, Ontario M5S 3H8, Canada
| | - Mark A Scheel
- Theoretical Astrophysics 350-17, California Institute of Technology, Pasadena, California 91125, USA
| | - Bela Szilagyi
- Theoretical Astrophysics 350-17, California Institute of Technology, Pasadena, California 91125, USA
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, USA
| | - Kenta Hotokezaka
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Koutarou Kyutoku
- Interdisciplinary Theoretical Science (iTHES) Research Group, RIKEN, Wako, Saitama 351-0198, Japan
| | - Masaru Shibata
- Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan
| | - Cory W Carpenter
- Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164, USA
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28
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Radebaugh J, Ventra D, Lorenz RD, Farr T, Kirk R, Hayes A, Malaska MJ, Birch S, Liu ZYC, Lunine J, Barnes J, Le Gall A, Lopes R, Stofan E, Wall S, Paillou P. Alluvial and fluvial fans on Saturn's moon Titan reveal processes, materials and regional geology. ACTA ACUST UNITED AC 2016. [DOI: 10.1144/sp440.6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractFans, landforms that record the storage and transport of sediment from uplands to depositional basins, are found on Saturn's moon Titan, a body of significantly different process rates and material compositions from Earth. Images obtained by the Cassini spacecraft's synthetic aperture radar reveal morphologies, roughness, textural patterns and other properties consistent with fan analogues on Earth also viewed by synthetic aperture radar. The observed fan characteristics on Titan reveal some regions of high relative relief and others with gentle slopes over hundreds of kilometres, exposing topographic variations and influences on fan formation. There is evidence for a range of particle sizes across proximal to distal fan regions, from c. 2 cm or more to fine-grained, which can provide details on sedimentary processes. Some features are best described as alluvial fans, which implies their proximity to high-relief source areas, while others are more likely to be fluvial fans, drawing from larger catchment areas and frequently characterized by more prolonged runoff events. The presence of fans corroborates the vast liquid storage capacity of the atmosphere and the resultant episodic behaviour. Fans join the growing list of landforms on Titan derived from atmospheric and fluvial processes similar to those on Earth, strengthening comparisons between these two planetary bodies.
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Affiliation(s)
- Jani Radebaugh
- Brigham Young University, S-389 ESC, Provo, UT 84601, USA
| | | | - Ralph D. Lorenz
- Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA
| | - Tom Farr
- NASA Jet Propulsion Laboratory, Pasadena, CA 91109, USA
| | - Randy Kirk
- US Geological Survey, Astrogeology Division, Flagstaff AZ 86001, USA
| | - Alex Hayes
- Department of Astronomy, Cornell University, Ithaca, NY 14853, USA
| | | | - Sam Birch
- Department of Astronomy, Cornell University, Ithaca, NY 14853, USA
| | - Zac Yung-Chun Liu
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA
| | - Jonathan Lunine
- Department of Astronomy, Cornell University, Ithaca, NY 14853, USA
| | - Jason Barnes
- Department of Physics, University of Idaho, Moscow, ID 83844, USA
| | - Alice Le Gall
- LATMOS Observatoire de Versailles Saint-Quentin-en-Yvelines (OVSQ), Paris, France
| | - Rosaly Lopes
- NASA Jet Propulsion Laboratory, Pasadena, CA 91109, USA
| | | | - Steve Wall
- NASA Jet Propulsion Laboratory, Pasadena, CA 91109, USA
| | - Philippe Paillou
- Observatoire Aquitain des Sciences de l'Univers, Universite de Bordeaux, Floirac, France
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29
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Taubner RS, Schleper C, Firneis MG, Rittmann SKMR. Assessing the Ecophysiology of Methanogens in the Context of Recent Astrobiological and Planetological Studies. Life (Basel) 2015; 5:1652-86. [PMID: 26703739 PMCID: PMC4695842 DOI: 10.3390/life5041652] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 10/15/2015] [Accepted: 11/10/2015] [Indexed: 12/31/2022] Open
Abstract
Among all known microbes capable of thriving under extreme and, therefore, potentially extraterrestrial environmental conditions, methanogens from the domain Archaea are intriguing organisms. This is due to their broad metabolic versatility, enormous diversity, and ability to grow under extreme environmental conditions. Several studies revealed that growth conditions of methanogens are compatible with environmental conditions on extraterrestrial bodies throughout the Solar System. Hence, life in the Solar System might not be limited to the classical habitable zone. In this contribution we assess the main ecophysiological characteristics of methanogens and compare these to the environmental conditions of putative habitats in the Solar System, in particular Mars and icy moons. Eventually, we give an outlook on the feasibility and the necessity of future astrobiological studies concerning methanogens.
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Affiliation(s)
- Ruth-Sophie Taubner
- Research Platform: ExoLife, University of Vienna, Türkenschanzstraße 17, 1180 Vienna, Austria.
- Institute of Astrophysics, University of Vienna, Türkenschanzstraße 17, 1180 Vienna, Austria.
| | - Christa Schleper
- Archaea Biology and Ecogenomics Division, Department of Ecogenomics and Systems Biology, University of Vienna, Althanstraße 14, 1090 Vienna, Austria.
| | - Maria G Firneis
- Research Platform: ExoLife, University of Vienna, Türkenschanzstraße 17, 1180 Vienna, Austria.
- Institute of Astrophysics, University of Vienna, Türkenschanzstraße 17, 1180 Vienna, Austria.
| | - Simon K-M R Rittmann
- Archaea Biology and Ecogenomics Division, Department of Ecogenomics and Systems Biology, University of Vienna, Althanstraße 14, 1090 Vienna, Austria.
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30
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Iess L, Stevenson DJ, Parisi M, Hemingway D, Jacobson RA, Lunine JI, Nimmo F, Armstrong JW, Asmar SW, Ducci M, Tortora P. The Gravity Field and Interior Structure of Enceladus. Science 2014; 344:78-80. [DOI: 10.1126/science.1250551] [Citation(s) in RCA: 269] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The small and active Saturnian moon Enceladus is one of the primary targets of the Cassini mission. We determined the quadrupole gravity field of Enceladus and its hemispherical asymmetry using Doppler data from three spacecraft flybys. Our results indicate the presence of a negative mass anomaly in the south-polar region, largely compensated by a positive subsurface anomaly compatible with the presence of a regional subsurface sea at depths of 30 to 40 kilometers and extending up to south latitudes of about 50°. The estimated values for the largest quadrupole harmonic coefficients (106J2= 5435.2 ± 34.9, 106C22= 1549.8 ± 15.6, 1σ) and their ratio (J2/C22= 3.51 ± 0.05) indicate that the body deviates mildly from hydrostatic equilibrium. The moment of inertia is around 0.335MR2, whereMis the mass andRis the radius, suggesting a differentiated body with a low-density core.
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31
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Grasset O, Bunce EJ, Coustenis A, Dougherty MK, Erd C, Hussmann H, Jaumann R, Prieto-Ballesteros O. Review of exchange processes on Ganymede in view of its planetary protection categorization. ASTROBIOLOGY 2013; 13:991-1004. [PMID: 24143869 DOI: 10.1089/ast.2013.1013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In this paper, we provide a detailed review of Ganymede's characteristics that are germane to any consideration of its planetary protection requirements. Ganymede is the largest moon in our solar system and is the subject of one of the main science objectives of the JUICE mission to the jovian system. We explore the probability of the occurrence of potentially habitable zones within Ganymede at present, including those both within the deep liquid ocean and those in shallow liquid reservoirs. We consider the possible exchange processes between the surface and any putative habitats to set some constraints on the planetary protection approach for this moon. As a conclusion, the "remote" versus "significant" chance of contamination will be discussed, according to our current understanding of this giant icy moon. Based on the different estimates we investigate here, it appears extremely unlikely that material would be exchanged downward through the upper icy layer of Ganymede and, thus, bring material into the ocean over timescales consistent with the survival of microorganisms.
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Affiliation(s)
- O Grasset
- 1 Planetology and Geodynamics, University of Nantes , CNRS, France
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32
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Abstract
Several lines of evidence suggest that Saturn's largest moon, Titan, has a global subsurface ocean beneath an outer ice shell 50 to 200 kilometres thick. If convection is occurring, the rigid portion of the shell is expected to be thin; similarly, a weak, isostatically compensated shell has been proposed to explain the observed topography. Here we report a strong inverse correlation between gravity and topography at long wavelengths that are not dominated by tides and rotation. We argue that negative gravity anomalies (mass deficits) produced by crustal thickening at the base of the ice shell overwhelm positive gravity anomalies (mass excesses) produced by the small surface topography, giving rise to this inverse correlation. We show that this situation requires a substantially rigid ice shell with an elastic thickness exceeding 40 kilometres, and hundreds of metres of surface erosion and deposition, consistent with recent estimates from local features. Our results are therefore not compatible with a geologically active, low-rigidity ice shell. After extrapolating to wavelengths that are controlled by tides and rotation, we suggest that Titan's moment of inertia may be even higher (that is, Titan may be even less centrally condensed) than is currently thought.
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33
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Carr CE, Rowedder H, Lui CS, Zlatkovsky I, Papalias CW, Bolander J, Myers JW, Bustillo J, Rothberg JM, Zuber MT, Ruvkun G. Radiation resistance of sequencing chips for in situ life detection. ASTROBIOLOGY 2013; 13:560-569. [PMID: 23734755 DOI: 10.1089/ast.2012.0923] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Life beyond Earth may be based on RNA or DNA if such life is related to life on Earth through shared ancestry due to meteoritic exchange, such as may be the case for Mars, or if delivery of similar building blocks to habitable environments has biased the evolution of life toward utilizing nucleic acids. In this case, in situ sequencing is a powerful approach to identify and characterize such life without the limitations or expense of returning samples to Earth, and can monitor forward contamination. A new semiconductor sequencing technology based on sensing hydrogen ions released during nucleotide incorporation can enable massively parallel sequencing in a small, robust, optics-free CMOS chip format. We demonstrate that these sequencing chips survive several analogues of space radiation at doses consistent with a 2-year Mars mission, including protons with solar particle event-distributed energy levels and 1 GeV oxygen and iron ions. We find no measurable impact of irradiation at 1 and 5 Gy doses on sequencing quality nor on low-level hardware characteristics. Further testing is required to study the impacts of soft errors as well as to characterize performance under neutron and gamma irradiation and at higher doses, which would be expected during operation in environments with significant trapped energetic particles such as during a mission to Europa. Our results support future efforts to use in situ sequencing to test theories of panspermia and/or whether life has a common chemical basis.
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Affiliation(s)
- Christopher E Carr
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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34
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Tides turn on Titan. Nature 2012. [DOI: 10.1038/nature.2012.10917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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