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Neish C, Malaska MJ, Sotin C, Lopes RMC, Nixon CA, Affholder A, Chatain A, Cockell C, Farnsworth KK, Higgins PM, Miller KE, Soderlund KM. Organic Input to Titan's Subsurface Ocean Through Impact Cratering. Astrobiology 2024; 24:177-189. [PMID: 38306187 DOI: 10.1089/ast.2023.0055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2024]
Abstract
Titan has an organic-rich atmosphere and surface with a subsurface liquid water ocean that may represent a habitable environment. In this work, we determined the amount of organic material that can be delivered from Titan's surface to its ocean through impact cratering. We assumed that Titan's craters produce impact melt deposits composed of liquid water that can founder in its lower-density ice crust and estimated the amount of organic molecules that could be incorporated into these melt lenses. We used known yields for HCN and Titan haze hydrolysis to determine the amount of glycine produced in the melt lenses and found a range of possible flux rates of glycine from the surface to the subsurface ocean. These ranged from 0 to 1011 mol/Gyr for HCN hydrolysis and from 0 to 1014 mol/Gyr for haze hydrolysis. These fluxes suggest an upper limit for biomass productivity of ∼103 kgC/year from a glycine fermentation metabolism. This upper limit is significantly less than recent estimates of the hypothetical biomass production supported by Enceladus's subsurface ocean. Unless biologically available compounds can be sourced from Titan's interior, or be delivered from the surface by other mechanisms, our calculations suggest that even the most organic-rich ocean world in the Solar System may not be able to support a large biosphere.
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Affiliation(s)
- Catherine Neish
- Department of Earth Sciences, The University of Western Ontario, London, Ontario, Canada
| | - Michael J Malaska
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Christophe Sotin
- Laboratoire de Planétologie et Géosciences, Nantes Université, Univ Angers, Le Mans Université, CNRS, UMR 6112, Nantes, France
| | - Rosaly M C Lopes
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Conor A Nixon
- Planetary Systems Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - Antonin Affholder
- Department of Ecology and Evolutionary Biology, The University of Arizona, Tucson, Arizona, USA
| | - Audrey Chatain
- Departamento de Física Aplicada, Escuela de Ingeniería de Bilbao, Universidad del País Vasco/Euskal Herriko Unibertsitatea (UPV/EHU), Bilbao, Spain
| | - Charles Cockell
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| | - Kendra K Farnsworth
- NASA Postdoctoral Program Fellow, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - Peter M Higgins
- Department of Earth Sciences, University of Toronto, Toronto, Ontario, Canada
| | | | - Krista M Soderlund
- Institute for Geophysics, Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas, USA
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Neveu M, Quinn R, Barge LM, Craft KL, German CR, Getty S, Glein C, Parra M, Burton AS, Cary F, Corpolongo A, Fifer L, Gangidine A, Gentry D, Georgiou CD, Haddadin Z, Herbold C, Inaba A, Jordan SF, Kalucha H, Klier P, Knicely K, Li AY, McNally P, Millan M, Naz N, Raj CG, Schroedl P, Timm J, Yang Z. Future of the Search for Life: Workshop Report. Astrobiology 2024; 24:114-129. [PMID: 38227837 DOI: 10.1089/ast.2022.0158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2024]
Abstract
The 2-week, virtual Future of the Search for Life science and engineering workshop brought together more than 100 scientists, engineers, and technologists in March and April 2022 to provide their expert opinion on the interconnections between life-detection science and technology. Participants identified the advances in measurement and sampling technologies they believed to be necessary to perform in situ searches for life elsewhere in our Solar System, 20 years or more in the future. Among suggested measurements for these searches, those pertaining to three potential indicators of life termed "dynamic disequilibrium," "catalysis," and "informational polymers" were identified as particularly promising avenues for further exploration. For these three indicators, small breakout groups of participants identified measurement needs and knowledge gaps, along with corresponding constraints on sample handling (acquisition and processing) approaches for a variety of environments on Enceladus, Europa, Mars, and Titan. Despite the diversity of these environments, sample processing approaches all tend to be more complex than those that have been implemented on missions or envisioned for mission concepts to date. The approaches considered by workshop breakout groups progress from nondestructive to destructive measurement techniques, and most involve the need for fluid (especially liquid) sample processing. Sample processing needs were identified as technology gaps. These gaps include technology and associated sampling strategies that allow the preservation of the thermal, mechanical, and chemical integrity of the samples upon acquisition; and to optimize the sample information obtained by operating suites of instruments on common samples. Crucially, the interplay between science-driven life-detection strategies and their technological implementation highlights the need for an unprecedented level of payload integration and extensive collaboration between scientists and engineers, starting from concept formulation through mission deployment of life-detection instruments and sample processing systems.
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Affiliation(s)
- Marc Neveu
- Department of Astronomy, University of Maryland, College Park, Maryland, USA
- NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - Richard Quinn
- NASA Ames Research Center, Moffett Field, California, USA
| | - Laura M Barge
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Kathleen L Craft
- Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland, USA
| | | | | | | | - Macarena Parra
- NASA Ames Research Center, Moffett Field, California, USA
| | | | - Francesca Cary
- Hawai'i Institute of Geophysics and Planetology, University of Hawai'i, Mānoa, Hawaii, USA
| | - Andrea Corpolongo
- Department of Geosciences, University of Cincinnati, Cincinnati, Ohio, USA
| | - Lucas Fifer
- Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA
| | - Andrew Gangidine
- Office of Development, Yale University, New Haven, Connecticut, USA
| | - Diana Gentry
- NASA Ames Research Center, Moffett Field, California, USA
| | | | - Zaid Haddadin
- Department of Electrical and Computer Engineering, University of California, San Diego, California, USA
| | - Craig Herbold
- School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - Aila Inaba
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, New Jersey, USA
| | - Seán F Jordan
- School of Chemical Sciences, Dublin City University, Dublin, Ireland
| | - Hemani Kalucha
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA
| | - Pavel Klier
- NASA Ames Research Center, Moffett Field, California, USA
- NASA Postdoctoral Program, Oak Ridge Associated Universities, Oak Ridge, Tennessee, USA
| | - Kas Knicely
- Geophysical Institute, University of Alaska, Fairbanks, Alaska, USA
| | - An Y Li
- Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA
| | - Patrick McNally
- Space Physics Research Laboratory, University of Michigan, Ann Arbor, Michigan, USA
| | - Maëva Millan
- Laboratory Atmosphere and Space Observations, Guyancourt, France
| | - Neveda Naz
- Department of Chemistry, Tufts University, Medford, Massachusetts, USA
| | - Chinmayee Govinda Raj
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Peter Schroedl
- Department of Biology, Boston University, Boston, Massachusetts, USA
| | - Jennifer Timm
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, New Jersey, USA
| | - Ziming Yang
- Department of Chemistry, Oakland University, Rochester, Michigan, USA
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3
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Tagliabue CF, Bissig D, Kaye J, Mazza V, Assecondi S. Feasibility of Remote Unsupervised Cognitive Screening With SATURN in Older Adults. J Appl Gerontol 2023; 42:1903-1910. [PMID: 36999483 PMCID: PMC10533744 DOI: 10.1177/07334648231166894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/01/2023] Open
Abstract
Widespread cognitive test screening as part of tele-public health initiatives necessitates a test that is self-administered online and automatically scored, with no clinician effort. The feasibility of unsupervised cognitive screening is unclear. We adapted the Self-Administered Tasks Uncovering Risk of Neurodegeneration (SATURN) to make it suitable for self-administration and automatic scoring. A sample of 364 healthy older adults completed SATURN via a web browser, in a fully independent manner. SATURN's overall score was not modulated by gender, education, reading speed, the time of day at which the test was taken, or an individual's familiarity with technology. SATURN proved extremely portable across operating systems. Importantly, comments from participants reported satisfaction with the experience and the clarity of the instructions. SATURN represents a fast and easy screening tool that can be used for a first assessment, during a routine test or clinical evaluation, or during periodic health monitoring, in person or remotely.
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Affiliation(s)
- Chiara F. Tagliabue
- Center for Mind/Brain Sciences - CIMeC, University of Trento, Rovereto (TN), Italy, 38068
| | - David Bissig
- Department of Neurology, University of California–Davis, Sacramento, California, USA, CA 95616
| | - Jeffrey Kaye
- Department of Neurology, Oregon Health and Science University, Portland, Oregon, USA, OR 97239
| | - Veronica Mazza
- Center for Mind/Brain Sciences - CIMeC, University of Trento, Rovereto (TN), Italy, 38068
| | - Sara Assecondi
- Center for Mind/Brain Sciences - CIMeC, University of Trento, Rovereto (TN), Italy, 38068
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Witze A. JWST spots biggest water plume yet spewing from a moon of Saturn. Nature 2023; 618:19. [PMID: 37202465 DOI: 10.1038/d41586-023-01666-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
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Moulay V, Freissinet C, Rizk-Bigourd M, Buch A, Ancelin M, Couturier E, Breton C, Trainer MG, Szopa C. Selection and Analytical Performances of the Dragonfly Mass Spectrometer Gas Chromatographic Columns to Support the Search for Organic Molecules of Astrobiological Interest on Titan. Astrobiology 2023; 23:213-229. [PMID: 36577024 DOI: 10.1089/ast.2022.0038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Titan is a key planetary body for astrobiology, with the presence of a subsurface ocean and a dense atmosphere, in which complex chemistry is known to occur. Approximately 1-Titan-year after the Cassini-Huygens mission arrived in the saturnian system, Dragonfly rotorcraft will land on Titan's surface by 2034 for an exhaustive geophysical and chemical investigation of the Shangri-La organic sand sea region. Among the four instruments onboard Dragonfly, the Dragonfly Mass Spectrometer (DraMS) is dedicated to analyze the chemical composition of surface samples and noble gases in the atmosphere. One of the DraMS analysis modes, the Gas Chromatograph-Mass Spectrometer (GC-MS), is devoted to the detection and identification of organic molecules that could be involved in the development of a prebiotic chemistry or even representative of traces of past or present life. Therefore, DraMS-GC subsystem should be optimized to detect and identify relevant organic compounds to meet this objective. This work is focused on the experimental methods employed to select the chromatographic column to be integrated in DraMS-GC, to assess the analytical performances of the column selected, and also to assess the performances of the second DraMS-GC column, which is devoted to the separation of organic enantiomers. Four different stationary phases have been tested to select the most relevant one for the separation of the targeted chemical species. The results show that the stationary phase composed of polymethyl (95%) diphenyl (5%) siloxane is the best compromise in terms of efficiency, robustness, and retention times of the molecules. The combination of the general and the chiral columns in DraMS is perfectly suited to in situ chemical analysis on Titan and for the detection of expected diverse and complex organic compounds.
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Affiliation(s)
- Valentin Moulay
- LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
| | - Caroline Freissinet
- LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
| | - Malak Rizk-Bigourd
- LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
| | - Arnaud Buch
- Laboratoire Génie des Procédés et Matériaux, CentraleSupelec, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Mayline Ancelin
- LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
| | - Elise Couturier
- LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
| | - Caroline Breton
- LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
| | - Melissa G Trainer
- Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - Cyril Szopa
- LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
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6
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MacKenzie SM, Neveu M, Davila AF, Lunine JI, Cable ML, Phillips-Lander CM, Eigenbrode JL, Waite JH, Craft KL, Hofgartner JD, McKay CP, Glein CR, Burton D, Kounaves SP, Mathies RA, Vance SD, Malaska MJ, Gold R, German CR, Soderlund KM, Willis P, Freissinet C, McEwen AS, Brucato JR, de Vera JPP, Hoehler TM, Heldmann J. Science Objectives for Flagship-Class Mission Concepts for the Search for Evidence of Life at Enceladus. Astrobiology 2022; 22:685-712. [PMID: 35290745 PMCID: PMC9233532 DOI: 10.1089/ast.2020.2425] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Cassini revealed that Saturn's Moon Enceladus hosts a subsurface ocean that meets the accepted criteria for habitability with bio-essential elements and compounds, liquid water, and energy sources available in the environment. Whether these conditions are sufficiently abundant and collocated to support life remains unknown and cannot be determined from Cassini data. However, thanks to the plume of oceanic material emanating from Enceladus' south pole, a new mission to Enceladus could search for evidence of life without having to descend through kilometers of ice. In this article, we outline the science motivations for such a successor to Cassini, choosing the primary science goal to be determining whether Enceladus is inhabited and assuming a resource level equivalent to NASA's Flagship-class missions. We selected a set of potential biosignature measurements that are complementary and orthogonal to build a robust case for any life detection result. This result would be further informed by quantifications of the habitability of the environment through geochemical and geophysical investigations into the ocean and ice shell crust. This study demonstrates that Enceladus' plume offers an unparalleled opportunity for in situ exploration of an Ocean World and that the planetary science and astrobiology community is well equipped to take full advantage of it in the coming decades.
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Affiliation(s)
- Shannon M. MacKenzie
- Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA
- Address correspondence to: Shannon M. MacKenzie, Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA
| | - Marc Neveu
- Department of Astronomy, University of Maryland, College Park, Maryland, USA
- Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - Alfonso F. Davila
- Division of Space Science and Astrobiology, NASA Ames Research Center, Moffett Field, California, USA
| | - Jonathan I. Lunine
- Department of Astronomy, Cornell University, Ithaca, New York, USA
- Carl Sagan Institute, Cornell University, Ithaca, New York, USA
| | - Morgan L. Cable
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | | | - Jennifer L. Eigenbrode
- Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - J. Hunter Waite
- Space Science and Engineering Division, Southwest Research Institute, San Antonio, Texas, USA
| | - Kate L. Craft
- Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA
| | - Jason D. Hofgartner
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Chris P. McKay
- Division of Space Science and Astrobiology, NASA Ames Research Center, Moffett Field, California, USA
| | - Christopher R. Glein
- Space Science and Engineering Division, Southwest Research Institute, San Antonio, Texas, USA
| | - Dana Burton
- Department of Anthropology, George Washington University, Washington, District of Columbia, USA
| | | | - Richard A. Mathies
- Chemistry Department and Space Sciences Laboratory, University of California, Berkeley, Berkeley, California, USA
| | - Steven D. Vance
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Michael J. Malaska
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Robert Gold
- Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA
| | - Christopher R. German
- Department of Geology & Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
| | - Krista M. Soderlund
- Institute for Geophysics, Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas, USA
| | - Peter Willis
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | | | - Alfred S. McEwen
- Lunar and Planetary Lab, University of Arizona, Tucson, Arizona, USA
| | | | - Jean-Pierre P. de Vera
- Space Operations and Astronaut Training, MUSC, German Aerospace Center (DLR), Cologne, Germany
| | - Tori M. Hoehler
- Division of Space Science and Astrobiology, NASA Ames Research Center, Moffett Field, California, USA
| | - Jennifer Heldmann
- Division of Space Science and Astrobiology, NASA Ames Research Center, Moffett Field, California, USA
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Baines KH, Nikolić D, Cutts JA, Delitsky ML, Renard JB, Madzunkov SM, Barge LM, Mousis O, Wilson C, Limaye SS, Verdier N. Investigation of Venus Cloud Aerosol and Gas Composition Including Potential Biogenic Materials via an Aerosol-Sampling Instrument Package. Astrobiology 2021; 21:1316-1323. [PMID: 33944604 DOI: 10.1089/ast.2021.0001] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A lightweight, low-power instrument package to measure, in situ, both (1) the local gaseous environment and (2) the composition and microphysical properties of attendant venusian aerosols is presented. This Aerosol-Sampling Instrument Package (ASIP) would be used to explore cloud chemical and possibly biotic processes on future aerial missions such as multiweek balloon missions and on short-duration (<1 h) probes on Venus and potentially on other cloudy worlds such as Titan, the Ice Giants, and Saturn. A quadrupole ion-trap mass spectrometer (QITMS; Madzunkov and Nikolić, J Am Soc Mass Spectrom 25:1841-1852, 2014) fed alternately by (1) an aerosol separator that injects only aerosols into a vaporizer and mass spectrometer and (2) the pure aerosol-filtered atmosphere, achieves the compositional measurements. Aerosols vaporized <600°C are measured over atomic mass ranges from 2 to 300 AMU at <0.02 AMU resolution, sufficient to measure trace materials, their isotopic ratios, and potential biogenic materials embedded within H2SO4 aerosols, to better than 20% in <300 s for H2SO4 -relative abundances of 2 × 10-9. An integrated lightweight, compact nephelometer/particle-counter determines the number density and particle sizes of the sampled aerosols.
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Affiliation(s)
- Kevin H Baines
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Dragan Nikolić
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - James A Cutts
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | | | | | - Stojan M Madzunkov
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Laura M Barge
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Olivier Mousis
- Aix Marseille Université, CNRS, CNES, LAM, Marseille, France
| | | | - Sanjay S Limaye
- Space Science and Engineering Center, University of Wisconsin-Madison, Wisconsin, USA
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8
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Abstract
The capacity to sense gradients efficiently and acquire information about the ambient environment confers many advantages such as facilitating movement toward nutrient sources or away from toxic chemicals. The amplified dispersal evinced by organisms endowed with motility is possibly beneficial in related contexts. Hence, the connections between information acquisition, motility, and microbial size are explored from an explicitly astrobiological standpoint. By using prior theoretical models, the constraints on organism size imposed by gradient detection and motility are elucidated in the form of simple heuristic scaling relations. It is argued that environments such as alkaline hydrothermal vents, which are distinguished by the presence of steep gradients, might be conducive to the existence of "small" microbes (with radii of ≳0.1 μm) in principle, when only the above two factors are considered; other biological functions (e.g., metabolism and genetic exchange) could, however, regulate the lower bound on microbial size and elevate it. The derived expressions are potentially applicable to a diverse array of settings, including those entailing solvents other than water; for example, the lakes and seas of Titan. The article concludes with a brief exposition of how this formalism may be of practical and theoretical value to astrobiology.
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Affiliation(s)
- Manasvi Lingam
- Department of Aerospace, Physics and Space Science, Florida Institute of Technology, Melbourne, Florida, USA
- Institute for Theory and Computation, Harvard University, Cambridge, Massachusetts, USA
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9
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Kessler EA. Technology's Palette: Voyager's Eyes and the Hyperchromatic Enhancement of Jupiter and Saturn. Technol Cult 2021; 62:1087-1118. [PMID: 34719514 DOI: 10.1353/tech.2021.0198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In the late 1970s and early 1980s, NASA's Voyager mission offered the first clear pictures of Jupiter and Saturn. These images show the planets in strikingly brilliant, recognizably engineered, psychedelic colors: technology's palette. The use of color was justified on epistemological grounds; it made visible scientifically compelling features. But color palette also has a history, one that has not been previously considered. This article takes up this history and adds to the literature on the visual culture of science. It establishes that the Jet Propulsion Laboratory's pioneering role in digital image processing, the color conventions adopted for representing Earth, and American counterculture of the 1960s and its attitudes toward technology together created the conditions that allowed for hyperchromatic views of the planets. Technology's palette enhanced the scientific understanding of Jupiter and Saturn, while simultaneously celebrating technologically enhanced vision and the promise of seeing by means of humanmachine collaborations.
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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: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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11
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Fayolle EC, Noell AC, Johnson PV, Hodyss R, Ponce A. Viability of Bacillus subtilis Spores Exposed to Ultraviolet Light at Ocean World Surface Temperatures. Astrobiology 2020; 20:889-896. [PMID: 32580565 DOI: 10.1089/ast.2019.2214] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
This work investigated microorganism survival under temperature and ultraviolet (UV) radiation conditions found at the surface of ice-covered ocean worlds. These studies were motivated by a desire to understand the ability of resilient forms of life to survive under such conditions as a proxy for potential endogenic life and to inform planetary protection protocols for future missions. To accomplish this, we irradiated Bacillus subtilis spores with solar-like UV photons at temperatures ranging from room temperature down to 11 K and reported survival fractions with respect to fluence. We observed an increase in survival at low temperatures and found that the inactivation rate follows an Arrhenius-type behavior above 60 K. For solar-photon fluxes and surface temperatures at Europa and Enceladus, we found that Bacillus subtilis spores would be inactivated in less than an hour when in direct sunlight.
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Affiliation(s)
- Edith C Fayolle
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Aaron C Noell
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Paul V Johnson
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Robert Hodyss
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Adrian Ponce
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
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12
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Klenner F, Postberg F, Hillier J, Khawaja N, Reviol R, Stolz F, Cable ML, Abel B, Nölle L. Analog Experiments for the Identification of Trace Biosignatures in Ice Grains from Extraterrestrial Ocean Worlds. Astrobiology 2020; 20:179-189. [PMID: 31825243 DOI: 10.1089/ast.2019.2065] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Reliable identification of biosignatures, such as amino acids, fatty acids, and peptides, on extraterrestrial ocean worlds is a key prerequisite for space missions that search for life or its emergence on these worlds. One promising approach is the use of high-performance in situ impact ionization mass spectrometers to sample water ice grains emerging from ocean-bearing moons such as Europa or Enceladus. A predecessor of such detectors, the Cosmic Dust Analyzer on board the Cassini spacecraft, has proven to be very successful in analyzing inorganic and organic ocean constituents and with that characterizing the habitability of Enceladus ocean. However, biosignatures have not been definitively identified in extraterrestrial ocean environments so far. Here, we investigate with an analog experiment the spectral appearance of amino acids, fatty acids, and peptides in water ice grains, together with their detection limits, as applicable to spaceborne mass spectrometers. We employ a laboratory-based laser induced liquid beam ion desorption technique, proven to simulate accurately the impact ionization mass spectra of water ice grains over a wide range of impact speeds. The investigated organics produce characteristic mass spectra, with molecular peaks as well as clearly identifiable, distinctive fragments. We find the detection limits of these key biosignatures to be at the μM or nM level, depending on the molecular species and instrument polarity, and infer that impact ionization mass spectrometers are most sensitive to the molecular peaks of these biosignatures at encounter velocities of 4-6 km/s.
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Affiliation(s)
- Fabian Klenner
- Institut für Geologische Wissenschaften, Freie Universität Berlin, Berlin, Germany
- Institut für Geowissenschaften, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
| | - Frank Postberg
- Institut für Geologische Wissenschaften, Freie Universität Berlin, Berlin, Germany
- Institut für Geowissenschaften, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
| | - Jon Hillier
- Institut für Geologische Wissenschaften, Freie Universität Berlin, Berlin, Germany
| | - Nozair Khawaja
- Institut für Geologische Wissenschaften, Freie Universität Berlin, Berlin, Germany
- Institut für Geowissenschaften, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
| | - René Reviol
- Institut für Geologische Wissenschaften, Freie Universität Berlin, Berlin, Germany
- Institut für Geowissenschaften, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
| | - Ferdinand Stolz
- Leibniz-Institut für Oberflächenmodifizierung, Leipzig, Germany
- Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Leipzig, Germany
| | - Morgan L Cable
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
| | - Bernd Abel
- Leibniz-Institut für Oberflächenmodifizierung, Leipzig, Germany
- Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Leipzig, Germany
| | - Lenz Nölle
- Institut für Geologische Wissenschaften, Freie Universität Berlin, Berlin, Germany
- Institut für Geowissenschaften, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
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13
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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: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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14
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Abstract
There has been considerable attention on how to detect life on other worlds by searching for biomolecules. However, there has been much less clarity as to when it becomes warranted to focus a mission on the search for life on another world. At a minimum, a life-detection mission should follow convincing evidence of (1) Liquid water of suitable salinity, past or present; (2) Carbon in the water; (3) Biologically available N in the water; (4) Biologically useful energy in the water; (5) Organic material that can possibly be of biological origin and a plausible strategy for sampling this material. Based on these prerequisites, the most promising targets for a life search are currently the plume of Enceladus and the subsurface of Mars-in equatorial lake bed sediments and in polar ice-cemented ground. Neither the surface of Europa nor the clouds of Venus meet the criteria listed here but may with further exploration.
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15
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Kahana A, Schmitt-Kopplin P, Lancet D. Enceladus: First Observed Primordial Soup Could Arbitrate Origin-of-Life Debate. Astrobiology 2019; 19:1263-1278. [PMID: 31328961 PMCID: PMC6785169 DOI: 10.1089/ast.2019.2029] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Accepted: 06/03/2019] [Indexed: 05/02/2023]
Abstract
A recent breakthrough publication has reported complex organic molecules in the plumes emanating from the subglacial water ocean of Saturn's moon Enceladus (Postberg et al., 2018, Nature 558:564-568). Based on detailed chemical scrutiny, the authors invoke primordial or endogenously synthesized carbon-rich monomers (<200 u) and polymers (up to 8000 u). This appears to represent the first reported extraterrestrial organics-rich water body, a conceivable milieu for early steps in life's origin ("prebiotic soup"). One may ask which origin-of-life scenario appears more consistent with the reported molecular configurations on Enceladus. The observed monomeric organics are carbon-rich unsaturated molecules, vastly different from present-day metabolites, amino acids, and nucleotide bases, but quite chemically akin to simple lipids. The organic polymers are proposed to resemble terrestrial insoluble kerogens and humic substances, as well as refractory organic macromolecules found in carbonaceous chondritic meteorites. The authors posit that such polymers, upon long-term hydrous interactions, might break down to micelle-forming amphiphiles. In support of this, published detailed analyses of the Murchison chondrite are dominated by an immense diversity of likely amphiphilic monomers. Our specific quantitative model for compositionally reproducing lipid micelles is amphiphile-based and benefits from a pronounced organic diversity. It thus contrasts with other origin models, which require the presence of very specific building blocks and are expected to be hindered by excess of irrelevant compounds. Thus, the Enceladus finds support the possibility of a pre-RNA Lipid World scenario for life's origin.
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Affiliation(s)
- Amit Kahana
- Department of Molecular Genetics, the Weizmann Institute of Science, Rehovot, Israel
| | - Philippe Schmitt-Kopplin
- Helmholtz Zentrum Muenchen, Research Unit Analytical BioGeoChemistry, Neuherberg, Germany
- Technische Universität München, Chair of Analytical Food Chemistry, Freising-Weihenstephan, Germany
| | - Doron Lancet
- Department of Molecular Genetics, the Weizmann Institute of Science, Rehovot, Israel
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16
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Kawai J, Kebukawa Y, McKay CP, Kobayashi K. Nucleic acid bases in Titan tholins and possible genetic systems in the Titan liquidosphere. Life Sci Space Res (Amst) 2019; 20:20-29. [PMID: 30797431 DOI: 10.1016/j.lssr.2018.11.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 11/18/2018] [Accepted: 11/26/2018] [Indexed: 06/09/2023]
Abstract
Titan is the largest moon of Saturn and possesses a dense atmosphere composed of nitrogen and methane. Various types of organic compounds (hydrocarbons, nitriles, etc.) have been found on Titan, which were generated by reactions taking place in its atmosphere. These reactions are considered to provide crucial evidence for chemical reactions which may have occurred in the atmosphere of primitive Earth. Cassini discovered several lakes of liquid methane and ethane on Titan's surface; in addition, the presence of ammonia water in its sub-surface was implied. In order to simulate the chemical reactions in Titan's atmosphere, gas mixtures of nitrogen and methane have been exposed to plasma discharges to synthesize complex organic matters. In this study, we focused on the formation of nucleic acid bases and related compounds recovered from synthesized Titan tholins. The five nucleic acid bases that terrestrial life uses (adenine, cytosine, thymine, guanine, and uracil) have already been reported to be present in synthesized Titan tholins. Purines and pyrimidines, including the five aforementioned nucleic acid bases, were extracted from synthesized Titan tholins and analyzed by HPLC and LC/MS. As a result, the pyrimidine bases of isocytosine and 2, 4-diaminopyrimidine were detected together with the terrestrial nucleic acid bases of adenine, uracil, and cytosine. The results obtained in conjunction with those from previous studies show that some nucleic acid bases and related pyrimidine bases are found in synthesized Titan tholins, suggesting that chemical evolutions toward xenogenetic systems could occur in Titan's environment.
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Affiliation(s)
- Jun Kawai
- High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan.
| | - Yoko Kebukawa
- Yokohama National University, 79-1 Tokiwadai, Hodogaya-ku, Yokohama, 240-8501, Japan.
| | | | - Kensei Kobayashi
- Yokohama National University, 79-1 Tokiwadai, Hodogaya-ku, Yokohama, 240-8501, Japan.
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17
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Postberg F, Khawaja N, Abel B, Choblet G, Glein CR, Gudipati MS, Henderson BL, Hsu HW, Kempf S, Klenner F, Moragas-Klostermeyer G, Magee B, Nölle L, Perry M, Reviol R, Schmidt J, Srama R, Stolz F, Tobie G, Trieloff M, Waite JH. Macromolecular organic compounds from the depths of Enceladus. Nature 2018; 558:564-568. [PMID: 29950623 PMCID: PMC6027964 DOI: 10.1038/s41586-018-0246-4] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 03/23/2018] [Indexed: 11/13/2022]
Abstract
Saturn's moon Enceladus harbours a global water ocean 1 , which lies under an ice crust and above a rocky core 2 . Through warm cracks in the crust 3 a cryo-volcanic plume ejects ice grains and vapour into space4-7 that contain materials originating from the ocean8,9. Hydrothermal activity is suspected to occur deep inside the porous core10-12, powered by tidal dissipation 13 . So far, only simple organic compounds with molecular masses mostly below 50 atomic mass units have been observed in plume material6,14,15. Here we report observations of emitted ice grains containing concentrated and complex macromolecular organic material with molecular masses above 200 atomic mass units. The data constrain the macromolecular structure of organics detected in the ice grains and suggest the presence of a thin organic-rich film on top of the oceanic water table, where organic nucleation cores generated by the bursting of bubbles allow the probing of Enceladus' organic inventory in enhanced concentrations.
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Affiliation(s)
- Frank Postberg
- Institut für Geowissenschaften, Universität Heidelberg, Heidelberg, Germany.
- Klaus-Tschira-Labor für Kosmochemie, Universität Heidelberg, Heidelberg, Germany.
- Institut für Geologische Wissenschaften, Freie Universität Berlin, Berlin, Germany.
| | - Nozair Khawaja
- Institut für Geowissenschaften, Universität Heidelberg, Heidelberg, Germany
| | - Bernd Abel
- Leibniz-Institute für Oberflächenmodifizierung (IOM), Leipzig, Germany
| | - Gael Choblet
- Laboratoire de Planétologie et Géodynamique, UMR-CNRS 6112, Université de Nantes, Nantes, France
| | - Christopher R Glein
- Space Science and Engineering Division, Southwest Research Institute, San Antonio, TX, USA
| | - Murthy S Gudipati
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Bryana L Henderson
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Hsiang-Wen Hsu
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
| | - Sascha Kempf
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
| | - Fabian Klenner
- Institut für Geowissenschaften, Universität Heidelberg, Heidelberg, Germany
| | | | - Brian Magee
- Space Science and Engineering Division, Southwest Research Institute, San Antonio, TX, USA
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
| | - Lenz Nölle
- Institut für Geowissenschaften, Universität Heidelberg, Heidelberg, Germany
| | - Mark Perry
- Applied Physics Laboratory, Johns Hopkins University, Laurel, MD, USA
| | - René Reviol
- Institut für Geowissenschaften, Universität Heidelberg, Heidelberg, Germany
| | - Jürgen Schmidt
- Astronomy Research Unit, University of Oulu, Oulu, Finland
| | - Ralf Srama
- Institut für Raumfahrtsysteme, Universität Stuttgart, Stuttgart, Germany
| | - Ferdinand Stolz
- Leibniz-Institute für Oberflächenmodifizierung (IOM), Leipzig, Germany
- Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Leipzig, Germany
| | - Gabriel Tobie
- Laboratoire de Planétologie et Géodynamique, UMR-CNRS 6112, Université de Nantes, Nantes, France
| | - Mario Trieloff
- Institut für Geowissenschaften, Universität Heidelberg, Heidelberg, Germany
- Klaus-Tschira-Labor für Kosmochemie, Universität Heidelberg, Heidelberg, Germany
| | - J Hunter Waite
- Laboratoire de Planétologie et Géodynamique, UMR-CNRS 6112, Université de Nantes, Nantes, France
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18
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Lorenz RD, Cabrol NA. Onboard Science Insights and Vehicle Dynamics from Scale-Model Trials of the Titan Mare Explorer (TiME) Capsule at Laguna Negra, Chile. Astrobiology 2018; 18:607-618. [PMID: 27870548 DOI: 10.1089/ast.2015.1303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A scale model of the proposed Titan Mare Explorer capsule was deployed at the Planetary Lake Lander field site at Laguna Negra, Chile. The tests served to calibrate models of wind-driven drift of the capsule and to understand its attitude motion in the wave field, as well as to identify dynamic and acoustic signatures of shoreline approach. This information enables formulation of onboard trigger criteria for near-shore science data acquisition. Key Words: Titan-Vehicle dynamics-Science autonomy-Lake. Astrobiology 18, 607-618.
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Affiliation(s)
- Ralph D Lorenz
- 1 Johns Hopkins University Applied Physics Laboratory , Laurel, Maryland
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19
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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: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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20
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Taubner RS, Pappenreiter P, Zwicker J, Smrzka D, Pruckner C, Kolar P, Bernacchi S, Seifert AH, Krajete A, Bach W, Peckmann J, Paulik C, Firneis MG, Schleper C, Rittmann SKMR. Biological methane production under putative Enceladus-like conditions. Nat Commun 2018; 9:748. [PMID: 29487311 PMCID: PMC5829080 DOI: 10.1038/s41467-018-02876-y] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 01/04/2018] [Indexed: 11/18/2022] Open
Abstract
The detection of silica-rich dust particles, as an indication for ongoing hydrothermal activity, and the presence of water and organic molecules in the plume of Enceladus, have made Saturn's icy moon a hot spot in the search for potential extraterrestrial life. Methanogenic archaea are among the organisms that could potentially thrive under the predicted conditions on Enceladus, considering that both molecular hydrogen (H2) and methane (CH4) have been detected in the plume. Here we show that a methanogenic archaeon, Methanothermococcus okinawensis, can produce CH4 under physicochemical conditions extrapolated for Enceladus. Up to 72% carbon dioxide to CH4 conversion is reached at 50 bar in the presence of potential inhibitors. Furthermore, kinetic and thermodynamic computations of low-temperature serpentinization indicate that there may be sufficient H2 gas production to serve as a substrate for CH4 production on Enceladus. We conclude that some of the CH4 detected in the plume of Enceladus might, in principle, be produced by methanogens.
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Affiliation(s)
- Ruth-Sophie Taubner
- Archaea Biology and Ecogenomics Division, Department of Ecogenomics and Systems Biology, Universität Wien, 1090, Vienna, Austria
- Department of Astrophysics, Universität Wien, 1180, Vienna, Austria
| | - Patricia Pappenreiter
- Institute for Chemical Technology of Organic Materials, Johannes Kepler Universität Linz, 4040, Linz, Austria
| | - Jennifer Zwicker
- Department of Geodynamics and Sedimentology, Center for Earth Sciences, Universität Wien, 1090, Vienna, Austria
| | - Daniel Smrzka
- Department of Geodynamics and Sedimentology, Center for Earth Sciences, Universität Wien, 1090, Vienna, Austria
| | - Christian Pruckner
- Archaea Biology and Ecogenomics Division, Department of Ecogenomics and Systems Biology, Universität Wien, 1090, Vienna, Austria
| | - Philipp Kolar
- Archaea Biology and Ecogenomics Division, Department of Ecogenomics and Systems Biology, Universität Wien, 1090, Vienna, Austria
| | | | | | | | - Wolfgang Bach
- Geoscience Department, Universität Bremen, 28359, Bremen, Germany
| | - Jörn Peckmann
- Department of Geodynamics and Sedimentology, Center for Earth Sciences, Universität Wien, 1090, Vienna, Austria
- Institute for Geology, Center for Earth System Research and Sustainability, Universität Hamburg, 20146, Hamburg, Germany
| | - Christian Paulik
- Institute for Chemical Technology of Organic Materials, Johannes Kepler Universität Linz, 4040, Linz, Austria
| | - Maria G Firneis
- Department of Astrophysics, Universität Wien, 1180, Vienna, Austria
| | - Christa Schleper
- Archaea Biology and Ecogenomics Division, Department of Ecogenomics and Systems Biology, Universität Wien, 1090, Vienna, Austria
| | - Simon K-M R Rittmann
- Archaea Biology and Ecogenomics Division, Department of Ecogenomics and Systems Biology, Universität Wien, 1090, Vienna, Austria.
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Abstract
Since Earth's biochemistry is carbon-based and water-borne, the main strategies for searching for life elsewhere are "follow the carbon" and "follow the water." Recently, however, there is a growing focus on the prospect that putative exotic life on other planets could rely on unearthly biochemistries. Here, we hypothesize a novel oxygen-free organic chemistry for supporting potential exotic biosystems, which is named CHN biochemistry. This oxygen-free CHN biochemistry starts from simple oxygen-free species (including hydrocarbons, hydrogen cyanide, and nitriles) and produces a range of functional macromolecules that may function in similar ways to terran macromolecules, such as sugars (cyanosugars), acids (cyanoacids), amino acids (amino cyanoacids), and nucleobases (cyanonucleobases). These CHN macromolecules could further interact with each other to generate higher "cyanoester" and "cyanoprotein" systems. In addition, theoretical calculations indicate that the energy changes of some reactions are consistent with their counterparts in Earth's biochemistry. The CHN biochemistry-based life would be applicable in habitats with a low bioavailability of oxygen, such as the alkane lakes of Titan and non-aquatic liquids on extrasolar bodies. Key Words: Oxygen-free biochemistry-Titan-Hydrocarbons-Hydrogen cyanide-Nitriles. Astrobiology 17, 1173-1181.
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Affiliation(s)
- Kong-Peng Lv
- Department of Earth Sciences, University of Hong Kong , Hong Kong
| | - Lucy Norman
- Department of Earth Sciences, University of Hong Kong , Hong Kong
| | - Yi-Liang Li
- Department of Earth Sciences, University of Hong Kong , Hong Kong
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22
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Voosen P. Food for microbes abundant on Enceladus. Science 2017; 356:121. [PMID: 28408551 DOI: 10.1126/science.356.6334.121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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23
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Abstract
Titan, the largest moon of Saturn, is one of the key planetary objects in the field of exobiology. Its dense, nitrogen-rich atmosphere is the site of important organic chemistry. This paper focuses on the organic aerosols produced in Titan's atmosphere that play an important role in atmospheric and surface processes and in organic chemistry as it applies to exobiological interests. To produce reliable laboratory analogues of these aerosols, we developed, tested, and optimized a device for the synthesis of clean tholins. The potential chemical evolution of Titan aerosols at Titan's surface has been studied, in particular, the possible interaction between aerosols and putative ammonia-water cryomagma. Modeling of the formation of Saturn's atmosphere has permitted the characterization of a composition of salts in the subsurface ocean and cryolava. From this new and original chemical composition, a laboratory study of several hydrolyses of tholins was carried out. The results obtained show the formation of many organic compounds, among them, species identified only in the presence of salts. In addition, a list of potential precursors of these compounds was established, which could provide a database for research of the chemical composition of tholins and/or aerosols of Titan. Key Words: Titan tholins-Titan aerosols-Hydrolysis-Carbonates-Titan's surface. Astrobiology 17, 8-26.
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Affiliation(s)
- Coralie Brassé
- 1 Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR CNRS 7583, Université Paris Est Créteil et Université Paris Diderot , Institut Pierre Simon Laplace, C.M.C., Créteil, France
| | - Arnaud Buch
- 2 Laboratoire de Génie des Procédés et Matériaux (LGPM) , Ecole Centrale Paris, Chatenay-Malabry, France
| | - Patrice Coll
- 1 Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR CNRS 7583, Université Paris Est Créteil et Université Paris Diderot , Institut Pierre Simon Laplace, C.M.C., Créteil, France
| | - François Raulin
- 1 Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR CNRS 7583, Université Paris Est Créteil et Université Paris Diderot , Institut Pierre Simon Laplace, C.M.C., Créteil, France
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24
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Hrušák J, Paidarová I. Step Towards Modeling the Atmosphere of Titan: State-Selected Reactions of O + with Methane. ORIGINS LIFE EVOL B 2016; 46:419-424. [PMID: 27068153 DOI: 10.1007/s11084-016-9503-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 01/07/2016] [Indexed: 11/26/2022]
Abstract
Methane conversion and in particular the formation of the C-O bond is one of fundamental entries to organic chemistry and it appears to be essential for understanding parts of atmospheric chemistry of Titan, but, in broader terms it might be also relevant for Earth-like exoplanets. Theoretical study of the reactions of methane with atomic oxygen ion in its excited electronic states requires treating simultaneously at least 19 electronic states. Development of a computational strategy that would allow chemically reasonable and computationally feasible treatment of the CH4 (X)/O+ (2D, 2P) system is by far not trivial and it requires careful examination of all the complex features of the corresponding 19 potential energy surfaces. Before entering the discussion of the rich (photo) chemistry, inspection of the long range behavior of the system with focus on electric dipole transition moments is required. Our calculations show nonzero probability for the reactants to decay before entering the multiple avoided crossings region of the [CH4 + O → products]+ reaction. For the CH4/O+ (2P) system non-zero transition moment probabilities occur over the entire range of considered C-O distances (up to 15 Å), while for the CH4/O+ (2D) system these probabilities are lower by one order of magnitude and were found only at C-O distances smaller than 6 Å.
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Affiliation(s)
- J Hrušák
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v. v. i., Dolejškova 3, 182 23, Prague, Czech Republic.
| | - I Paidarová
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v. v. i., Dolejškova 3, 182 23, Prague, Czech Republic
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Zymak I, Žabka J, Polášek M, Španěl P, Smith D. A Pilot Study of Ion - Molecule Reactions at Temperatures Relevant to the Atmosphere of Titan. ORIGINS LIFE EVOL B 2016; 46:533-538. [PMID: 27108425 DOI: 10.1007/s11084-016-9499-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 12/16/2015] [Indexed: 11/27/2022]
Abstract
Reliable theoretical models of the chemical kinetics of the ionosphere of Saturn's moon, Titan, is highly dependent on the precision of the rates of the reactions of ambient ions with hydrocarbon molecules at relevant temperatures. A Variable Temperature Selected Ions Flow Tube technique, which has been developed primarily to study these reactions at temperatures within the range of 200-330 K, is briefly described. The flow tube temperature regulation system and the thermalisation of ions are also discussed. Preliminary studies of two reactions have been carried out to check the reliability and efficacy of kinetics measurements: (i) Rate constants of the reaction of CH3+ ions with molecular oxygen were measured at different temperatures, which indicate values in agreement with previous ion cyclotron resonance measurements ostensibly made at 300 K. (ii) Formation of CH3+ ions in the reaction of N2+ ions with CH4 molecules were studied at temperatures within the range 240-310 K which showed a small but statistically significant decrease of the ratio of product CH3+ ions to reactant N2+ ions with reaction temperature.
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Affiliation(s)
- Illia Zymak
- J. Heyrovský Institute of Physical Chemistry of the ASCR, Dolejškova 2155/3, 182 23, Prague 8, Czech Republic.
| | - Ján Žabka
- J. Heyrovský Institute of Physical Chemistry of the ASCR, Dolejškova 2155/3, 182 23, Prague 8, Czech Republic
| | - Miroslav Polášek
- J. Heyrovský Institute of Physical Chemistry of the ASCR, Dolejškova 2155/3, 182 23, Prague 8, Czech Republic
| | - Patrik Španěl
- J. Heyrovský Institute of Physical Chemistry of the ASCR, Dolejškova 2155/3, 182 23, Prague 8, Czech Republic
| | - David Smith
- Institute for Science and Technology in Medicine, School of Medicine, Keele University, Thornburrow Drive, Hartshill, Stoke-on-Trent, ST4 7QB, UK
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Nadeau J, Lindensmith C, Deming JW, Fernandez VI, Stocker R. Microbial Morphology and Motility as Biosignatures for Outer Planet Missions. Astrobiology 2016; 16:755-774. [PMID: 27552160 PMCID: PMC5069736 DOI: 10.1089/ast.2015.1376] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 06/13/2016] [Indexed: 05/23/2023]
Abstract
Meaningful motion is an unambiguous biosignature, but because life in the Solar System is most likely to be microbial, the question is whether such motion may be detected effectively on the micrometer scale. Recent results on microbial motility in various Earth environments have provided insight into the physics and biology that determine whether and how microorganisms as small as bacteria and archaea swim, under which conditions, and at which speeds. These discoveries have not yet been reviewed in an astrobiological context. This paper discusses these findings in the context of Earth analog environments and environments expected to be encountered in the outer Solar System, particularly the jovian and saturnian moons. We also review the imaging technologies capable of recording motility of submicrometer-sized organisms and discuss how an instrument would interface with several types of sample-collection strategies. Key Words: In situ measurement-Biosignatures-Microbiology-Europa-Ice. Astrobiology 16, 755-774.
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Affiliation(s)
- Jay Nadeau
- 1 GALCIT, California Institute of Technology , Pasadena, California
| | - Chris Lindensmith
- 2 Jet Propulsion Laboratory, California Institute of Technology , Pasadena, California
| | - Jody W Deming
- 3 Department of Biological Oceanography, University of Washington , Seattle, Washington
| | - Vicente I Fernandez
- 4 Department of Civil and Environmental Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts
| | - Roman Stocker
- 4 Department of Civil and Environmental Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts
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Abstract
It has been widely reported that Jupiter has a profound role in shielding the terrestrial planets from comet impacts in the Solar System, and that a jovian planet is a requirement for the evolution of life on Earth. To evaluate whether jovians, in fact, shield habitable planets from impacts (a phenomenon often referred to as the "Jupiter as shield" concept), this study simulated the evolution of 10,000 particles in each of the jovian inter-planet gaps for the cases of full-mass and embryo planets for up to 100 My. The results of these simulations predict a number of phenomena that not only discount the "Jupiter as shield" concept, they also predict that in a Solar System like ours, large gas giants like Saturn and Jupiter had a different, and potentially even more important, role in the evolution of life on our planet by delivering the volatile-laden material required for the formation of life. The simulations illustrate that, although all particles occupied "non-life threatening" orbits at their onset of the simulations, a significant fraction of the 30,000 particles evolved into Earth-crossing orbits. A comparison of multiple runs with different planetary configurations revealed that Jupiter was responsible for the vast majority of the encounters that "kicked" outer planet material into the terrestrial planet region, and that Saturn assisted in the process far more than has previously been acknowledged. Jupiter also tends to "fix" the aphelion of planetesimals at its orbit irrespective of their initial starting zones, which has the effect of slowing their passages through the inner Solar System, and thus potentially improving the odds of accretion of cometary material by terrestrial planets. As expected, the simulations indicate that the full-mass planets perturb many objects into the deep outer Solar System, or eject them entirely; however, planetary embryos also did this with surprising efficiency. Finally, the simulations predict that Jupiter's capacity to shield or intercept Earth-bound comets originating in the outer Solar System is poor, and that the importance of jovian planets on the formation of life is not that they act as shields, but rather that they deliver life-enabling volatiles to the terrestrial planets.
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Affiliation(s)
- Kevin R Grazier
- Jet Propulsion Laboratory, California Institute of Technology , Pasadena, California
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Taubner RS, Leitner JJ, Firneis MG, Hitzenberger R. Modelling the Interior Structure of Enceladus Based on the 2014's Cassini Gravity Data. ORIGINS LIFE EVOL B 2015; 46:283-8. [PMID: 26559966 DOI: 10.1007/s11084-015-9475-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2014] [Accepted: 10/29/2015] [Indexed: 11/25/2022]
Abstract
We present a model for the internal structure of Saturn's moon Enceladus. This model allows us to estimate the physical conditions at the bottom of the satellite's potential subsurface water reservoir and to determine the radial distribution of pressure and gravity. This leads to a better understanding of the physical and chemical conditions at the water/rock boundary. This boundary is the most promising area on icy moons for astrobiological studies as it could serve as a potential habitat for extraterrestrial life similar to terrestrial microbes that inhabit rocky mounds on Earth's sea floors.
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Affiliation(s)
- R-S Taubner
- Research Platform: ExoLife, University of Vienna, Türkenschanzstraße 17, 1180, Vienna, Austria.
- Institute of Astrophysics, University of Vienna, Türkenschanzstraße 17, 1180, Vienna, Austria.
| | - J J Leitner
- Research Platform: ExoLife, University of Vienna, Türkenschanzstraße 17, 1180, Vienna, Austria
- Institute of Astrophysics, University of Vienna, Türkenschanzstraße 17, 1180, Vienna, Austria
| | - M G Firneis
- Research Platform: ExoLife, University of Vienna, Türkenschanzstraße 17, 1180, Vienna, Austria
- Institute of Astrophysics, University of Vienna, Türkenschanzstraße 17, 1180, Vienna, Austria
| | - R Hitzenberger
- Research Platform: ExoLife, University of Vienna, Türkenschanzstraße 17, 1180, Vienna, Austria
- Aerosolphysics and Environmental Physics, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090, Vienna, Austria
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McLendon C, Opalko FJ, Illangkoon HI, Benner SA. Solubility of polyethers in hydrocarbons at low temperatures. A model for potential genetic backbones on warm titans. Astrobiology 2015; 15:200-206. [PMID: 25761113 DOI: 10.1089/ast.2014.1212] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Ethers are proposed here as the repeating backbone linking units in linear genetic biopolymers that might support Darwinian evolution in hydrocarbon oceans. Hydrocarbon oceans are found in our own solar system as methane mixtures on Titan. They may be found as mixtures of higher alkanes (propane, for example) on warmer hydrocarbon-rich planets in exosolar systems ("warm Titans"). We report studies on the solubility of several short polyethers in propane over its liquid range (from 85 to 231 K, or -188 °C to -42 °C). These show that polyethers are reasonably soluble in propane at temperatures down to ca. 200 K. However, their solubilities drop dramatically at still lower temperatures and become immeasurably low below 170 K, still well above the ∼ 95 K in Titan's oceans. Assuming that a liquid phase is essential for any living system, and genetic biopolymers must dissolve in that biosolvent to support Darwinism, these data suggest that we must look elsewhere to identify linear biopolymers that might support genetics in Titan's surface oceans. However, genetic molecules with polyether backbones may be suitable to support life in hydrocarbon oceans on warm Titans, where abundant organics and environments lacking corrosive water might make it easier for life to originate.
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Heller R, Williams D, Kipping D, Limbach MA, Turner E, Greenberg R, Sasaki T, Bolmont É, Grasset O, Lewis K, Barnes R, Zuluaga JI. Formation, habitability, and detection of extrasolar moons. Astrobiology 2014; 14:798-835. [PMID: 25147963 PMCID: PMC4172466 DOI: 10.1089/ast.2014.1147] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 06/05/2014] [Indexed: 06/03/2023]
Abstract
The diversity and quantity of moons in the Solar System suggest a manifold population of natural satellites exist around extrasolar planets. Of peculiar interest from an astrobiological perspective, the number of sizable moons in the stellar habitable zones may outnumber planets in these circumstellar regions. With technological and theoretical methods now allowing for the detection of sub-Earth-sized extrasolar planets, the first detection of an extrasolar moon appears feasible. In this review, we summarize formation channels of massive exomoons that are potentially detectable with current or near-future instruments. We discuss the orbital effects that govern exomoon evolution, we present a framework to characterize an exomoon's stellar plus planetary illumination as well as its tidal heating, and we address the techniques that have been proposed to search for exomoons. Most notably, we show that natural satellites in the range of 0.1-0.5 Earth mass (i) are potentially habitable, (ii) can form within the circumplanetary debris and gas disk or via capture from a binary, and (iii) are detectable with current technology.
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Affiliation(s)
- René Heller
- Origins Institute, Department of Physics and Astronomy, McMaster University, Hamilton, Canada
| | - Darren Williams
- The Behrend College School of Science, Penn State Erie, Erie, Pennsylvania, USA
| | - David Kipping
- Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA
| | - Mary Anne Limbach
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey, USA
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey, USA
| | - Edwin Turner
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey, USA
- The Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo, Kashiwa, Japan
| | - Richard Greenberg
- Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA
| | | | - Émeline Bolmont
- Université de Bordeaux, LAB, UMR 5804, Floirac, France
- CNRS, LAB, UMR 5804, Floirac, France
| | - Olivier Grasset
- Planetology and Geodynamics, University of Nantes, CNRS, Nantes, France
| | - Karen Lewis
- Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo, Japan
| | - Rory Barnes
- Astronomy Department, University of Washington, Seattle, Washington, USA
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
| | - Jorge I. Zuluaga
- FACom—Instituto de Física—FCEN, Universidad de Antioquia, Medellín, Colombia
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Abstract
The astrobiological exploration of other worlds in our Solar System is moving from initial exploration to more focused astrobiology missions. In this context, we present the case that the plume of Enceladus currently represents the best astrobiology target in the Solar System. Analysis of the plume by the Cassini mission indicates that the steady plume derives from a subsurface liquid water reservoir that contains organic carbon, biologically available nitrogen, redox energy sources, and inorganic salts. Furthermore, samples from the plume jetting out into space are accessible to a low-cost flyby mission. No other world has such well-studied indications of habitable conditions. Thus, the science goals that would motivate an Enceladus mission are more advanced than for any other Solar System body. The goals of such a mission must go beyond further geophysical characterization, extending to the search for biomolecular evidence of life in the organic-rich plume. This will require improved in situ investigations and a sample return.
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Li A, Jjunju FPM, Cooks RG. Nucleophilic addition of nitrogen to aryl cations: mimicking Titan chemistry. J Am Soc Mass Spectrom 2013; 24:1745-1754. [PMID: 23982933 DOI: 10.1007/s13361-013-0710-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 07/08/2013] [Accepted: 07/08/2013] [Indexed: 06/02/2023]
Abstract
The reactivity of aryl cations toward molecular nitrogen is studied systematically in an ion trap mass spectrometer at 10(2) Pascal of nitrogen, the pressure of the Titan main haze layer. Nucleophilic addition of dinitrogen occurs and the nature of aryl group has a significant influence on the reactivity, through inductive effects and by changing the ground state spin multiplicity. The products of nitrogen activation, aryldiazonium ions, react with typical nitriles, aromatic amines, and alkynes (compounds that are relevant as possible Titan atmosphere constituents) to form covalently bonded heterocyclic products. Theoretical calculations at the level [DFT(B3LYP)/6-311++G(d,p)] indicate that the N2 addition reaction is exothermic for the singlet aryl cations but endothermic for their triplet spin isomers. The -OH and -NH2 substituted aryl ions are calculated to have triplet ground states, which is consistent with their decreased nitrogen addition reactivity. The energy needed for the generation of the aryl cations from their protonated precursors (ca. 340 kJ/mol starting with protonated aniline) is far less than that required to directly activate the nitrogen triple bond (the lowest energy excited state of N2 lies ca. 600 kJ/mol above the ground state). The formation of aza-aromatics via arene ionization and subsequent reactions provide a conceivable route to the genesis of nitrogen-containing organic molecules in the interstellar medium and Titan haze layers.
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Affiliation(s)
- Anyin Li
- Chemistry Department, Purdue University, West Lafayette, IN, 47907, USA
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Omar H, Hashim NM, Zajmi A, Nordin N, Abdelwahab SI, Azizan AHS, Hadi AHA, Ali HM. Aporphine alkaloids from the leaves of Phoebe grandis (Nees) Mer. (Lauraceae) and their cytotoxic and antibacterial activities. Molecules 2013; 18:8994-9009. [PMID: 23899833 PMCID: PMC6270335 DOI: 10.3390/molecules18088994] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 07/16/2013] [Accepted: 07/22/2013] [Indexed: 11/30/2022] Open
Abstract
The oxoaporphine alkaloid lysicamine (1), and three proaporphine alkaloids, litsericinone (2), 8,9,11,12-tetrahydromecambrine (3) and hexahydromecambrine A (4) were isolated from the leaves of Phoebe grandis (Nees) Merr. (Lauraceae). Compounds 2 and 3 were first time isolated as new naturally occurring compounds from plants. The NMR data for the compounds 2-4 have never been reported so far. Compounds 1 and 2 showed significant cytotoxic activity against a MCF7 (human estrogen receptor (ER+) positive breast cancer) cell line with IC₅₀ values of 26 and 60 µg/mL, respectively. Furthermore, in vitro cytotoxic activity against HepG2 (human liver cancer) cell line was evaluated for compounds 1-4 with IC₅₀ values of 27, 14, 81 and 20 µg/mL, respectively. Lysicamine (1) displayed strong antibacterial activity against Bacillus subtilis (B145), Staphylococcus aureus (S1434) and Staphylococus epidermidis (a clinically isolated strain) with inhibition zones of 15.50 ± 0.57, 13.33 ± 0.57 and 12.00 ± 0.00 mm, respectively. However, none of the tested pathogenic bacteria were susceptible towards compounds 2 and 3.
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Affiliation(s)
- Hanita Omar
- Chemistry Department, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia; E-Mails: (A.H.S.A.); (A.H.A.H.)
- Centre for Foundation Studies in Sciences, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Najihah Mohd. Hashim
- Department of Pharmacy, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; E-Mails: (N.M.H.); (A.Z.); (N.N.)
| | - Asdren Zajmi
- Department of Pharmacy, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; E-Mails: (N.M.H.); (A.Z.); (N.N.)
| | - Noraziah Nordin
- Department of Pharmacy, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; E-Mails: (N.M.H.); (A.Z.); (N.N.)
| | | | - Ainnul Hamidah Syahadah Azizan
- Chemistry Department, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia; E-Mails: (A.H.S.A.); (A.H.A.H.)
| | - A. Hamid A. Hadi
- Chemistry Department, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia; E-Mails: (A.H.S.A.); (A.H.A.H.)
| | - Hapipah Mohd Ali
- Chemistry Department, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia; E-Mails: (A.H.S.A.); (A.H.A.H.)
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Kerr RA. Lunar and planetary science conference. More support for an ocean in Enceladus. Science 2013; 340:139. [PMID: 23580506 DOI: 10.1126/science.340.6129.139-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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35
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Savashinskaia NS, Shashmurina VR, Latyshev AV, Kirillov SK. [Experimental base for construction alloy choice for implant-retained restorations]. Stomatologiia (Mosk) 2013; 92:17-20. [PMID: 23752831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The paper contains the results of experimental studies on galvanic features of "implant-construction alloy" contact pair. These results may be used as criteria for implant-retained restorations alloy choice.
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36
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Baĭrikov IM, Amirov RS, Baĭrikov AI. [Experimental studies on the use of unwoven through-porous titanium material]. Stomatologiia (Mosk) 2013; 92:15-16. [PMID: 23752830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The paper describes titanium unwoven material with a through porosity (so called metal-rubber) designed for the manufacture of the intraosseous part of dental implants. Morphological processes occurring in and around the implants were studied in animal model.
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Shin K, Kumar R, Udachin KA, Alavi S, Ripmeester JA. Ammonia clathrate hydrates as new solid phases for Titan, Enceladus, and other planetary systems. Proc Natl Acad Sci U S A 2012; 109:14785-90. [PMID: 22908239 PMCID: PMC3443173 DOI: 10.1073/pnas.1205820109] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
There is interest in the role of ammonia on Saturn's moons Titan and Enceladus as the presence of water, methane, and ammonia under temperature and pressure conditions of the surface and interior make these moons rich environments for the study of phases formed by these materials. Ammonia is known to form solid hemi-, mono-, and dihydrate crystal phases under conditions consistent with the surface of Titan and Enceladus, but has also been assigned a role as water-ice antifreeze and methane hydrate inhibitor which is thought to contribute to the outgassing of methane clathrate hydrates into these moons' atmospheres. Here we show, through direct synthesis from solution and vapor deposition experiments under conditions consistent with extraterrestrial planetary atmospheres, that ammonia forms clathrate hydrates and participates synergistically in clathrate hydrate formation in the presence of methane gas at low temperatures. The binary structure II tetrahydrofuran + ammonia, structure I ammonia, and binary structure I ammonia + methane clathrate hydrate phases synthesized have been characterized by X-ray diffraction, molecular dynamics simulation, and Raman spectroscopy methods.
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Affiliation(s)
- Kyuchul Shin
- Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, ON, Canada K1A 0R6; and
| | - Rajnish Kumar
- National Chemical Laboratory, Council of Scientific and Industrial Research, Pune 411008, India
| | - Konstantin A. Udachin
- Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, ON, Canada K1A 0R6; and
| | - Saman Alavi
- Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, ON, Canada K1A 0R6; and
| | - John A. Ripmeester
- Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, ON, Canada K1A 0R6; and
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38
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Hörst SM, Yelle RV, Buch A, Carrasco N, Cernogora G, Dutuit O, Quirico E, Sciamma-O'Brien E, Smith MA, Somogyi A, Szopa C, Thissen R, Vuitton V. Formation of amino acids and nucleotide bases in a Titan atmosphere simulation experiment. Astrobiology 2012; 12:809-17. [PMID: 22917035 PMCID: PMC3444770 DOI: 10.1089/ast.2011.0623] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The discovery of large (>100 u) molecules in Titan's upper atmosphere has heightened astrobiological interest in this unique satellite. In particular, complex organic aerosols produced in atmospheres containing C, N, O, and H, like that of Titan, could be a source of prebiotic molecules. In this work, aerosols produced in a Titan atmosphere simulation experiment with enhanced CO (N(2)/CH(4)/CO gas mixtures of 96.2%/2.0%/1.8% and 93.2%/5.0%/1.8%) were found to contain 18 molecules with molecular formulae that correspond to biological amino acids and nucleotide bases. Very high-resolution mass spectrometry of isotopically labeled samples confirmed that C(4)H(5)N(3)O, C(4)H(4)N(2)O(2), C(5)H(6)N(2)O(2), C(5)H(5)N(5), and C(6)H(9)N(3)O(2) are produced by chemistry in the simulation chamber. Gas chromatography-mass spectrometry (GC-MS) analyses of the non-isotopic samples confirmed the presence of cytosine (C(4)H(5)N(3)O), uracil (C(5)H(4)N(2)O(2)), thymine (C(5)H(6)N(2)O(2)), guanine (C(5)H(5)N(5)O), glycine (C(2)H(5)NO(2)), and alanine (C(3)H(7)NO(2)). Adenine (C(5)H(5)N(5)) was detected by GC-MS in isotopically labeled samples. The remaining prebiotic molecules were detected in unlabeled samples only and may have been affected by contamination in the chamber. These results demonstrate that prebiotic molecules can be formed by the high-energy chemistry similar to that which occurs in planetary upper atmospheres and therefore identifies a new source of prebiotic material, potentially increasing the range of planets where life could begin.
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Affiliation(s)
- S M Hörst
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309, USA.
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Lorenz RD. Thermal drilling in planetary ices: an analytic solution with application to planetary protection problems of radioisotope power sources. Astrobiology 2012; 12:799-802. [PMID: 22897131 DOI: 10.1089/ast.2012.0816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Thermal drilling has been applied to studies of glaciers on Earth and proposed for study of the martian ice caps and the crust of Europa. Additionally, inadvertent thermal drilling by radioisotope sources released from the breakup of a space vehicle is of astrobiological concern in that this process may form a downward-propagating "warm little pond" that could convey terrestrial biota to a habitable environment. A simple analytic solution to the asymptotic slow-speed case of thermal drilling is noted and used to show that the high thermal conductivity of the low-temperature ice on Europa and Titan makes thermal drilling qualitatively more difficult than at Mars. It is shown that an isolated General Purpose Heat Source (GPHS) "brick" can drill effectively on Earth or Mars, whereas on Titan or Europa with ice at 100 K, the source would stall and become stuck in the ice with a surface temperature of <200 K.
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Affiliation(s)
- Ralph D Lorenz
- Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland 20723, USA.
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Cottin H, Guan YY, Noblet A, Poch O, Saiagh K, Cloix M, Macari F, Jérome M, Coll P, Raulin F, Stalport F, Szopa C, Bertrand M, Chabin A, Westall F, Chaput D, Demets R, Brack A. The PROCESS experiment: an astrochemistry laboratory for solid and gaseous organic samples in low-earth orbit. Astrobiology 2012; 12:412-425. [PMID: 22680688 DOI: 10.1089/ast.2011.0773] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The PROCESS (PRebiotic Organic ChEmistry on the Space Station) experiment was part of the EXPOSE-E payload outside the European Columbus module of the International Space Station from February 2008 to August 2009. During this interval, organic samples were exposed to space conditions to simulate their evolution in various astrophysical environments. The samples used represent organic species related to the evolution of organic matter on the small bodies of the Solar System (carbonaceous asteroids and comets), the photolysis of methane in the atmosphere of Titan, and the search for organic matter at the surface of Mars. This paper describes the hardware developed for this experiment as well as the results for the glycine solid-phase samples and the gas-phase samples that were used with regard to the atmosphere of Titan. Lessons learned from this experiment are also presented for future low-Earth orbit astrochemistry investigations.
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Affiliation(s)
- Hervé Cottin
- Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR CNRS 7583, Université Paris Est Créteil et Université Paris Diderot, Institut Pierre Simon Laplace, Créteil, France.
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Coustenis A. From the land of Greece to the lands of Titan. Astrobiology 2012; 12:170-174. [PMID: 22468885 DOI: 10.1089/ast.2011.0810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Affiliation(s)
- Athena Coustenis
- Laboratoire d’Etudes Spatiales et d’Instrumentation en Astrophysique, Observatoire de Paris, UPMC Université Paris, Université Paris-Diderot, France.
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Gvetadze RS, Rusanov FS, Mikhas'kov SV. [Study of physical-mechanic characteristics of prosthetic construction after their adjustment with the use of laser welding and hot metal adding]. Stomatologiia (Mosk) 2011; 90:63-65. [PMID: 21983619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Study of physical-mechanic characteristics of connecting joints of beam construction after laser welding and hot metal adding was performed. Increase of microhardness of joints as well as small reduction of bending strength of prosthetic constructions was established.
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Abstract
Titan organic haze analogues, or "tholins," produce biomolecules when hydrolyzed at low temperature over long timescales. By using a combination of high-resolution mass spectroscopy and tandem mass spectrometry fragmentation techniques, four amino acids were identified in a tholin sample that had been hydrolyzed in a 13 wt % ammonia-water solution at 253 + or - 1 K and 293 + or - 1 K for 1 year. These four species have been assigned as the amino acids asparagine, aspartic acid, glutamine, and glutamic acid. This represents the first detection of biologically relevant molecules created under conditions thought to be similar to those found in impact melt pools and cryolavas on Titan, which are at a stage of chemical evolution not unlike the "primordial soup" of the early Earth. Future missions to Titan should therefore carry instrumentation capable of, but certainly not limited to, detecting amino acids and other prebiotic molecules on Titan's surface.
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Affiliation(s)
- Catherine D Neish
- Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723-6099, USA.
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Nott J. Titan: a distant but enticing destination for human visitors. Aviat Space Environ Med 2009; 80:900-901. [PMID: 19817245 DOI: 10.3357/asem.2596.2009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Until recently, very little was known about Saturn's largest satellite, Titan. But that has changed dramatically since the Cassini spacecraft started orbiting in the Saturn system in 2004. Larger than Mercury and with a dense atmosphere, Titan has many of the characteristics of a planet. Indeed, many scientists now see it as the most interesting place in the Solar System for robotic exploration, with many unique features and even the possibility of exotic forms of life. This paper points out that Titan is also a potential destination for humans. With its predominantly nitrogen atmosphere, moderate gravity, and available water and oxygen, it also appears that, once it becomes possible to travel there, it will prove to be much more hospitable for human visitors than any other destination in the Solar System.
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Affiliation(s)
- Julian Nott
- Nott Technology, LLC, Santa Barbara, CA, USA.
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Abstract
Cassini radar recently detected several putative liquid hydrocarbon lakes in the polar region of Saturn's moon Titan. Such lakes may contain organic sediments deposited from the atmosphere that would promote prebiotic-type chemistry driven by cosmic rays, the result of which could be the production of more complex molecules such as nitrogen-bearing organic polymer or azides. The physical properties of the lake and their temporal evolution under Titan's present climatic setting were investigated by means of a one-dimensional lake thermal stratification model. Lakes can undergo various evolutions, depending on the initial composition and depth of the lake and hydrocarbon abundance in the near-surface atmosphere. Pure methane ponds, which may occasionally form when heavy methane hailstones reach the surface, would be transitory in that they would evaporate, freeze up, and eventually dry up. On the other hand, lakes filled with a mixture of methane, ethane, and nitrogen would be more stable; and freezing or drying would not necessarily occur in most cases. Such lakes undergo a seasonal cycle of thermal stratification in spring and early summer and convective overturning in other seasons. The summer thermal stratification near the lake surface could be destabilized by bottom heating as a result of an enhanced geothermal heat flux, e.g., in the vicinity of cryovolcanoes. Most likely the composition of the lake and atmosphere would come to equilibrium by way of a small amount of evaporation, but the lake-atmosphere system could be repeatedly brought out of equilibrium by irregular precipitation. The viability of prebiotic-like chemistry in the lake may depend on many lake parameters, such as temperature, liquid or frozen state, and convective mixing. Moreover, convective mixing may drive suspension of solid acetylene and other sediments on the lake bottom and redistribution of dissolved gases, which might be relevant for putative life-forms that consume hydrogen and solid acetylene.
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Affiliation(s)
- Tetsuya Tokano
- Institut für Geophysik und Meteorologie, Universität zu Köln, Köln, Germany.
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Abstract
With the recent success of the Huygens lander on Titan, a moon of Saturn, there has been renewed interest in further exploring the acoustic environments of the other planets in the solar system. The direct simulation Monte Carlo (DSMC) method is used here for modeling sound propagation in the atmospheres of Earth, Mars, and Titan at a variety of altitudes above the surface. DSMC is a particle method that describes gas dynamics through direct physical modeling of particle motions and collisions. The validity of DSMC for the entire range of Knudsen numbers (Kn), where Kn is defined as the mean free path divided by the wavelength, allows for the exploration of sound propagation in planetary environments for all values of Kn. DSMC results at a variety of altitudes on Earth, Mars, and Titan including the details of nonlinearity, absorption, dispersion, and molecular relaxation in gas mixtures are given for a wide range of Kn showing agreement with various continuum theories at low Kn and deviation from continuum theory at high Kn. Despite large computation time and memory requirements, DSMC is the method best suited to study high altitude effects or where continuum theory is not valid.
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Affiliation(s)
- Amanda D Hanford
- Applied Research Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16804, USA.
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McKay CP, Porco CC, Altheide T, Davis WL, Kral TA. The possible origin and persistence of life on Enceladus and detection of biomarkers in the plume. Astrobiology 2008; 8:909-919. [PMID: 18950287 DOI: 10.1089/ast.2008.0265] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The jets of icy particles and water vapor issuing from the south pole of Enceladus are evidence for activity driven by some geophysical energy source. The vapor has also been shown to contain simple organic compounds, and the south polar terrain is bathed in excess heat coming from below. The source of the ice and vapor, and the mechanisms that accelerate the material into space, remain obscure. However, it is possible that a liquid water environment exists beneath the south polar cap, which may be conducive to life. Several theories for the origin of life on Earth would apply to Enceladus. These are (1) origin in an organic-rich mixture, (2) origin in the redox gradient of a submarine vent, and (3) panspermia. There are three microbial ecosystems on Earth that do not rely on sunlight, oxygen, or organics produced at the surface and, thus, provide analogues for possible ecologies on Enceladus. Two of these ecosystems are found deep in volcanic rock, and the primary productivity is based on the consumption by methanogens of hydrogen produced by rock reactions with water. The third ecosystem is found deep below the surface in South Africa and is based on sulfur-reducing bacteria consuming hydrogen and sulfate, both of which are ultimately produced by radioactive decay. Methane has been detected in the plume of Enceladus and may be biological in origin. An indicator of biological origin may be the ratio of non-methane hydrocarbons to methane, which is very low (0.001) for biological sources but is higher (0.1-0.01) for nonbiological sources. Thus, Cassini's instruments may detect plausible evidence for life by analysis of hydrocarbons in the plume during close encounters.
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Affiliation(s)
- Christopher P McKay
- Space Science Division, NASA Ames Research Center, Moffett Field, California 94035, USA.
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Parkinson CD, Liang MC, Yung YL, Kirschivnk JL. Habitability of enceladus: planetary conditions for life. ORIGINS LIFE EVOL B 2008; 38:355-69. [PMID: 18566911 DOI: 10.1007/s11084-008-9135-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Accepted: 04/10/2008] [Indexed: 12/01/2022]
Abstract
The prolific activity and presence of a plume on Saturn's tiny moon Enceladus offers us a unique opportunity to sample the interior composition of an icy satellite, and to look for interesting chemistry and possible signs of life. Based on studies of the potential habitability of Jupiter's moon Europa, icy satellite oceans can be habitable if they are chemically mixed with the overlying ice shell on Myr time scales. We hypothesize that Enceladus' plume, tectonic processes, and possible liquid water ocean may create a complete and sustainable geochemical cycle that may allow it to support life. We discuss evidence for surface/ocean material exchange on Enceladus based on the amounts of silicate dust material present in the Enceladus' plume particles. Microphysical cloud modeling of Enceladus' plume shows that the particles originate from a region of Enceladus' near surface where the temperature exceeds 190 K. This could be consistent with a shear-heating origin of Enceladus' tiger stripes, which would indicate extremely high temperatures ( approximately 250-273 K) in the subsurface shear fault zone, leading to the generation of subsurface liquid water, chemical equilibration between surface and subsurface ices, and crustal recycling on a time scale of 1 to 5 Myr. Alternatively, if the tiger stripes form in a mid-ocean-ridge-type mechanism, a half-spreading rate of 1 m/year is consistent with the observed regional heat flux of 250 mW m(-2) and recycling of south polar terrain crust on a 1 to 5 Myr time scale as well.
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Affiliation(s)
- Christopher D Parkinson
- Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, MI 48109, USA.
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