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Méndez A, Rivera-Valentín EG, Schulze-Makuch D, Filiberto J, Ramírez RM, Wood TE, Dávila A, McKay C, Ceballos KNO, Jusino-Maldonado M, Torres-Santiago NJ, Nery G, Heller R, Byrne PK, Malaska MJ, Nathan E, Simões MF, Antunes A, Martínez-Frías J, Carone L, Izenberg NR, Atri D, Chitty HIC, Nowajewski-Barra P, Rivera-Hernández F, Brown CY, Lynch KL, Catling D, Zuluaga JI, Salazar JF, Chen H, González G, Jagadeesh MK, Haqq-Misra J. Habitability Models for Astrobiology. ASTROBIOLOGY 2021; 21:1017-1027. [PMID: 34382857 DOI: 10.1089/ast.2020.2342] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Habitability has been generally defined as the capability of an environment to support life. Ecologists have been using Habitat Suitability Models (HSMs) for more than four decades to study the habitability of Earth from local to global scales. Astrobiologists have been proposing different habitability models for some time, with little integration and consistency among them, being different in function to those used by ecologists. Habitability models are not only used to determine whether environments are habitable, but they also are used to characterize what key factors are responsible for the gradual transition from low to high habitability states. Here we review and compare some of the different models used by ecologists and astrobiologists and suggest how they could be integrated into new habitability standards. Such standards will help improve the comparison and characterization of potentially habitable environments, prioritize target selections, and study correlations between habitability and biosignatures. Habitability models are the foundation of planetary habitability science, and the synergy between ecologists and astrobiologists is necessary to expand our understanding of the habitability of Earth, the Solar System, and extrasolar planets.
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Affiliation(s)
- Abel Méndez
- Planetary Habitability Laboratory, University of Puerto Rico at Arecibo, Puerto Rico, USA
| | | | - Dirk Schulze-Makuch
- Center for Astronomy and Astrophysics, Technische Universität Berlin, Berlin, Germany; German Research Centre for Geosciences, Section Geomicrobiology, Potsdam, Germany; Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Stechlin, Germany
| | | | - Ramses M Ramírez
- University of Central Florida, Department of Physics, Orlando, Florida, USA; Space Science Institute, Boulder, Colorado, USA
| | - Tana E Wood
- USDA Forest Service International Institute of Tropical Forestry, San Juan, Puerto Rico, USA
| | - Alfonso Dávila
- NASA Ames Research Center, Moffett Field, California, USA
| | - Chris McKay
- NASA Ames Research Center, Moffett Field, California, USA
| | - Kevin N Ortiz Ceballos
- Planetary Habitability Laboratory, University of Puerto Rico at Arecibo, Puerto Rico, USA
| | | | | | | | - René Heller
- Max Planck Institute for Solar System Research; Institute for Astrophysics, University of Göttingen, Germany
| | - Paul K Byrne
- North Carolina State University, Raleigh, North Carolina, USA
| | - Michael J Malaska
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Erica Nathan
- Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, Rhode Island, USA
| | - Marta Filipa Simões
- State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Taipa, Macau SAR, China
| | - André Antunes
- State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Taipa, Macau SAR, China
| | | | | | - Noam R Izenberg
- Johns Hopkins Applied Physics Laboratory, Laurel, Maryland, USA
| | - Dimitra Atri
- Center for Space Science, New York University Abu Dhabi, United Arab Emirates
| | | | | | | | | | - Kennda L Lynch
- Lunar and Planetary Institute, USRA, Houston, Texas, USA
| | | | - Jorge I Zuluaga
- Institute of Physics / FCEN - Universidad de Antioquia, Medellín, Colombia
| | - Juan F Salazar
- GIGA, Escuela Ambiental, Facultad de Ingeniería, Universidad de Antioquia, Medellín, Colombia
| | - Howard Chen
- Northwestern University, Evanston, Illinois, USA
| | - Grizelle González
- USDA Forest Service International Institute of Tropical Forestry, San Juan, Puerto Rico, USA
| | | | - Jacob Haqq-Misra
- Blue Marble Space Institute of Science, Seattle, Washington, USA
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Schulze-Makuch D, Heller R, Guinan E. In Search for a Planet Better than Earth: Top Contenders for a Superhabitable World. ASTROBIOLOGY 2020; 20:1394-1404. [PMID: 32955925 PMCID: PMC7757576 DOI: 10.1089/ast.2019.2161] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 08/07/2020] [Indexed: 06/11/2023]
Abstract
The fact that Earth is teeming with life makes it appear odd to ask whether there could be other planets in our galaxy that may be even more suitable for life. Neglecting this possible class of "superhabitable" planets, however, could be considered anthropocentric and geocentric biases. Most important from the perspective of an observer searching for extrasolar life is that such a search might be executed most effectively with a focus on superhabitable planets instead of Earth-like planets. We argue that there could be regions of astrophysical parameter space of star-planet systems that could allow for planets to be even better for life than our Earth. We aim to identify those parameters and their optimal ranges, some of which are astrophysically motivated, whereas others are based on the varying habitability of the natural history of our planet. Some of these conditions are far from being observationally testable on planets outside the solar system. Still, we can distill a short list of 24 top contenders among the >4000 exoplanets known today that could be candidates for a superhabitable planet. In fact, we argue that, with regard to the search for extrasolar life, potentially superhabitable planets may deserve higher priority for follow-up observations than most Earth-like planets.
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Affiliation(s)
- Dirk Schulze-Makuch
- Astrobiology Group, Center for Astronomy and Astrophysics, Technische Universität Berlin, Berlin, Germany
- GFZ German Research Center for Geosciences, Section Geomicrobiology, Potsdam, Germany
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Department of Experimental Limnology, Stechlin, Germany
- School of the Environment, Washington State University, Pullman, Washington, USA
| | - René Heller
- Max Planck Institute for Solar System Research, Göttingen, Germany
- Institute for Astrophysics, Georg-August University, Göttingen, Germany
| | - Edward Guinan
- Department of Astrophysics and Planetary Science, Villanova University, Villanova, Pennsylvania, USA
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Quarles B, Barnes JW, Lissauer JJ, Chambers J. Obliquity Evolution of the Potentially Habitable Exoplanet Kepler-62f. ASTROBIOLOGY 2020; 20:73-90. [PMID: 31613645 DOI: 10.1089/ast.2018.1932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Variations in the axial tilt, or obliquity, of terrestrial planets can affect their climates and therefore their habitability. Kepler-62f is a 1.4 R⊕ planet orbiting within the habitable zone of its K2 dwarf host star. We perform N-body simulations that monitor the evolution of obliquity of Kepler-62f for 10-million-year timescales to explore the effects on model assumptions, such as the masses of the Kepler-62 planets and the possibility of outer bodies. Significant obliquity variation occurs when the rotational precession frequency overlaps with one or more of the secular orbital frequencies, but most variations are limited to ≲10°. Moderate variations (∼10-20°) can occur over a broader range of initial obliquities when the relative nodal longitude (ΔΩ) overlaps with the frequency and phase of a given secular mode. However, we find that adding outer gas giants on long-period orbits (∼1000 days) can produce large (∼60°) variations in obliquity if Kepler-62f has a very rapid (4 h) rotation period. The possibility of giant planets on long-period orbits impacts the climate and habitability of Kepler-62f through variations in the latitudinal surface flux, where large variations can occur on million year timescales.
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Affiliation(s)
- Billy Quarles
- Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, Atlanta, Georgia
| | - Jason W Barnes
- Department of Physics, University of Idaho, Moscow, Idaho
| | - Jack J Lissauer
- NASA Ames Research Center, Astrobiology and Space Science Division MS 245-3, Moffett Field, California
| | - John Chambers
- Department of Terrestrial Magnetism, Carnegie Institution for Science, Washington, District of Columbia
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Fujii Y, Angerhausen D, Deitrick R, Domagal-Goldman S, Grenfell JL, Hori Y, Kane SR, Pallé E, Rauer H, Siegler N, Stapelfeldt K, Stevenson KB. Exoplanet Biosignatures: Observational Prospects. ASTROBIOLOGY 2018; 18:739-778. [PMID: 29938537 PMCID: PMC6016572 DOI: 10.1089/ast.2017.1733] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 03/13/2018] [Indexed: 05/04/2023]
Abstract
Exoplanet hunting efforts have revealed the prevalence of exotic worlds with diverse properties, including Earth-sized bodies, which has fueled our endeavor to search for life beyond the Solar System. Accumulating experiences in astrophysical, chemical, and climatological characterization of uninhabitable planets are paving the way to characterization of potentially habitable planets. In this paper, we review our possibilities and limitations in characterizing temperate terrestrial planets with future observational capabilities through the 2030s and beyond, as a basis of a broad range of discussions on how to advance "astrobiology" with exoplanets. We discuss the observability of not only the proposed biosignature candidates themselves but also of more general planetary properties that provide circumstantial evidence, since the evaluation of any biosignature candidate relies on its context. Characterization of temperate Earth-sized planets in the coming years will focus on those around nearby late-type stars. The James Webb Space Telescope (JWST) and later 30-meter-class ground-based telescopes will empower their chemical investigations. Spectroscopic studies of potentially habitable planets around solar-type stars will likely require a designated spacecraft mission for direct imaging, leveraging technologies that are already being developed and tested as part of the Wide Field InfraRed Survey Telescope (WFIRST) mission. Successful initial characterization of a few nearby targets will be an important touchstone toward a more detailed scrutiny and a larger survey that are envisioned beyond 2030. The broad outlook this paper presents may help develop new observational techniques to detect relevant features as well as frameworks to diagnose planets based on the observables. Key Words: Exoplanets-Biosignatures-Characterization-Planetary atmospheres-Planetary surfaces. Astrobiology 18, 739-778.
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Affiliation(s)
- Yuka Fujii
- NASA Goddard Institute for Space Studies, New York, New York, USA
- Earth-Life Science Institute, Tokyo Institute of Technology, Ookayama, Meguro, Tokyo, Japan
| | - Daniel Angerhausen
- CSH Fellow for Exoplanetary Astronomy, Center for Space and Habitability (CSH), Universität Bern, Bern, Switzerland
- Blue Marble Space Institute of Science, Seattle, Washington, USA
| | - Russell Deitrick
- Department of Astronomy, University of Washington, Seattle, Washington, USA
- NASA Astrobiology Institute's Virtual Planetary Laboratory
| | - Shawn Domagal-Goldman
- NASA Astrobiology Institute's Virtual Planetary Laboratory
- NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - John Lee Grenfell
- Department of Extrasolar Planets and Atmospheres (EPA), Institute of Planetary Research, German Aerospace Centre (DLR), Berlin, Germany
| | - Yasunori Hori
- Astrobiology Center, National Institutes of Natural Sciences (NINS), Mitaka, Tokyo, Japan
| | - Stephen R. Kane
- Department of Earth Sciences, University of California, Riverside, California, USA
| | - Enric Pallé
- Instituto de Astrofísica de Canarias, La Laguna, Tenerife, Spain
- Departamento de Astrofísica, Universidad de La Laguna, Tenerife, Spain
| | - Heike Rauer
- Department of Extrasolar Planets and Atmospheres (EPA), Institute of Planetary Research, German Aerospace Centre (DLR), Berlin, Germany
- Center for Astronomy and Astrophysics, Berlin Institute of Technology, Berlin, Germany
| | - Nicholas Siegler
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
- NASA Exoplanet Exploration Office
| | - Karl Stapelfeldt
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
- NASA Exoplanet Exploration Office
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Catling DC, Krissansen-Totton J, Kiang NY, Crisp D, Robinson TD, DasSarma S, Rushby AJ, Del Genio A, Bains W, Domagal-Goldman S. Exoplanet Biosignatures: A Framework for Their Assessment. ASTROBIOLOGY 2018; 18:709-738. [PMID: 29676932 PMCID: PMC6049621 DOI: 10.1089/ast.2017.1737] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 12/05/2017] [Indexed: 05/04/2023]
Abstract
Finding life on exoplanets from telescopic observations is an ultimate goal of exoplanet science. Life produces gases and other substances, such as pigments, which can have distinct spectral or photometric signatures. Whether or not life is found with future data must be expressed with probabilities, requiring a framework of biosignature assessment. We present a framework in which we advocate using biogeochemical "Exo-Earth System" models to simulate potential biosignatures in spectra or photometry. Given actual observations, simulations are used to find the Bayesian likelihoods of those data occurring for scenarios with and without life. The latter includes "false positives" wherein abiotic sources mimic biosignatures. Prior knowledge of factors influencing planetary inhabitation, including previous observations, is combined with the likelihoods to give the Bayesian posterior probability of life existing on a given exoplanet. Four components of observation and analysis are necessary. (1) Characterization of stellar (e.g., age and spectrum) and exoplanetary system properties, including "external" exoplanet parameters (e.g., mass and radius), to determine an exoplanet's suitability for life. (2) Characterization of "internal" exoplanet parameters (e.g., climate) to evaluate habitability. (3) Assessment of potential biosignatures within the environmental context (components 1-2), including corroborating evidence. (4) Exclusion of false positives. We propose that resulting posterior Bayesian probabilities of life's existence map to five confidence levels, ranging from "very likely" (90-100%) to "very unlikely" (<10%) inhabited. Key Words: Bayesian statistics-Biosignatures-Drake equation-Exoplanets-Habitability-Planetary science. Astrobiology 18, 709-738.
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Affiliation(s)
- David C. Catling
- Astrobiology Program, Department of Earth and Space Sciences, University of Washington, Seattle, Washington
- Virtual Planetary Laboratory, University of Washington, Seattle, Washington
| | - Joshua Krissansen-Totton
- Astrobiology Program, Department of Earth and Space Sciences, University of Washington, Seattle, Washington
- Virtual Planetary Laboratory, University of Washington, Seattle, Washington
| | - Nancy Y. Kiang
- NASA Goddard Institute for Space Studies, New York, New York
| | - David Crisp
- MS 233-200, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
| | - Tyler D. Robinson
- Department of Astronomy and Astrophysics, University of California, Santa Cruz, California
| | - Shiladitya DasSarma
- Department of Microbiology and Immunology, School of Medicine, and Institute of Marine and Environmental Technology, University of Maryland, Baltimore, Maryland
| | | | | | - William Bains
- Department of Earth, Atmospheric and Planetary Science, Cambridge, Massachusetts
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Meadows VS, Arney GN, Schwieterman EW, Lustig-Yaeger J, Lincowski AP, Robinson T, Domagal-Goldman SD, Deitrick R, Barnes RK, Fleming DP, Luger R, Driscoll PE, Quinn TR, Crisp D. The Habitability of Proxima Centauri b: Environmental States and Observational Discriminants. ASTROBIOLOGY 2018; 18:133-189. [PMID: 29431479 PMCID: PMC5820795 DOI: 10.1089/ast.2016.1589] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 09/04/2017] [Indexed: 05/21/2023]
Abstract
Proxima Centauri b provides an unprecedented opportunity to understand the evolution and nature of terrestrial planets orbiting M dwarfs. Although Proxima Cen b orbits within its star's habitable zone, multiple plausible evolutionary paths could have generated different environments that may or may not be habitable. Here, we use 1-D coupled climate-photochemical models to generate self-consistent atmospheres for several evolutionary scenarios, including high-O2, high-CO2, and more Earth-like atmospheres, with both oxic and anoxic compositions. We show that these modeled environments can be habitable or uninhabitable at Proxima Cen b's position in the habitable zone. We use radiative transfer models to generate synthetic spectra and thermal phase curves for these simulated environments, and use instrument models to explore our ability to discriminate between possible planetary states. These results are applicable not only to Proxima Cen b but to other terrestrial planets orbiting M dwarfs. Thermal phase curves may provide the first constraint on the existence of an atmosphere. We find that James Webb Space Telescope (JWST) observations longward of 10 μm could characterize atmospheric heat transport and molecular composition. Detection of ocean glint is unlikely with JWST but may be within the reach of larger-aperture telescopes. Direct imaging spectra may detect O4 absorption, which is diagnostic of massive water loss and O2 retention, rather than a photosynthetic biosphere. Similarly, strong CO2 and CO bands at wavelengths shortward of 2.5 μm would indicate a CO2-dominated atmosphere. If the planet is habitable and volatile-rich, direct imaging will be the best means of detecting habitability. Earth-like planets with microbial biospheres may be identified by the presence of CH4-which has a longer atmospheric lifetime under Proxima Centauri's incident UV-and either photosynthetically produced O2 or a hydrocarbon haze layer. Key Words: Planetary habitability and biosignatures-Planetary atmospheres-Exoplanets-Spectroscopic biosignatures-Planetary science-Proxima Centauri b. Astrobiology 18, 133-189.
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Affiliation(s)
- Victoria S. Meadows
- Astronomy Department, University of Washington, Seattle, Washington
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
| | - Giada N. Arney
- Astronomy Department, University of Washington, Seattle, Washington
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
- Planetary Systems Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland
| | - Edward W. Schwieterman
- Astronomy Department, University of Washington, Seattle, Washington
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
- NASA Postdoctoral Program, Universities Space Research Association, Columbia, Maryland
- Department of Earth Sciences, University of California at Riverside, Riverside, California
| | - Jacob Lustig-Yaeger
- Astronomy Department, University of Washington, Seattle, Washington
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
| | - Andrew P. Lincowski
- Astronomy Department, University of Washington, Seattle, Washington
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
| | - Tyler Robinson
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
- Department of Astronomy and Astrophysics, University of California, Santa Cruz, California
| | - Shawn D. Domagal-Goldman
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
- Planetary Environments Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland
| | - Russell Deitrick
- Astronomy Department, University of Washington, Seattle, Washington
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
| | - Rory K. Barnes
- Astronomy Department, University of Washington, Seattle, Washington
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
| | - David P. Fleming
- Astronomy Department, University of Washington, Seattle, Washington
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
| | - Rodrigo Luger
- Astronomy Department, University of Washington, Seattle, Washington
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
| | - Peter E. Driscoll
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
- Department of Terrestrial Magnetism, Carnegie Institution for Science, Washington, DC
| | - Thomas R. Quinn
- Astronomy Department, University of Washington, Seattle, Washington
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
| | - David Crisp
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
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7
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Multiple Climate States of Habitable Exoplanets: The Role of Obliquity and Irradiance. ACTA ACUST UNITED AC 2017. [DOI: 10.3847/1538-4357/aa7a03] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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10
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Domagal-Goldman SD, Wright KE, Adamala K, Arina de la Rubia L, Bond J, Dartnell LR, Goldman AD, Lynch K, Naud ME, Paulino-Lima IG, Singer K, Walther-Antonio M, Abrevaya XC, Anderson R, Arney G, Atri D, Azúa-Bustos A, Bowman JS, Brazelton WJ, Brennecka GA, Carns R, Chopra A, Colangelo-Lillis J, Crockett CJ, DeMarines J, Frank EA, Frantz C, de la Fuente E, Galante D, Glass J, Gleeson D, Glein CR, Goldblatt C, Horak R, Horodyskyj L, Kaçar B, Kereszturi A, Knowles E, Mayeur P, McGlynn S, Miguel Y, Montgomery M, Neish C, Noack L, Rugheimer S, Stüeken EE, Tamez-Hidalgo P, Imari Walker S, Wong T. The Astrobiology Primer v2.0. ASTROBIOLOGY 2016; 16:561-653. [PMID: 27532777 PMCID: PMC5008114 DOI: 10.1089/ast.2015.1460] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 06/06/2016] [Indexed: 05/09/2023]
Affiliation(s)
- Shawn D Domagal-Goldman
- 1 NASA Goddard Space Flight Center , Greenbelt, Maryland, USA
- 2 Virtual Planetary Laboratory , Seattle, Washington, USA
| | - Katherine E Wright
- 3 University of Colorado at Boulder , Colorado, USA
- 4 Present address: UK Space Agency, UK
| | - Katarzyna Adamala
- 5 Department of Genetics, Cell Biology and Development, University of Minnesota , Minneapolis, Minnesota, USA
| | | | - Jade Bond
- 7 Department of Physics, University of New South Wales , Sydney, Australia
| | | | | | - Kennda Lynch
- 10 Division of Biological Sciences, University of Montana , Missoula, Montana, USA
| | - Marie-Eve Naud
- 11 Institute for research on exoplanets (iREx) , Université de Montréal, Montréal, Canada
| | - Ivan G Paulino-Lima
- 12 Universities Space Research Association , Mountain View, California, USA
- 13 Blue Marble Space Institute of Science , Seattle, Washington, USA
| | - Kelsi Singer
- 14 Southwest Research Institute , Boulder, Colorado, USA
| | | | - Ximena C Abrevaya
- 16 Instituto de Astronomía y Física del Espacio (IAFE) , UBA-CONICET, Ciudad Autónoma de Buenos Aires, Argentina
| | - Rika Anderson
- 17 Department of Biology, Carleton College , Northfield, Minnesota, USA
| | - Giada Arney
- 18 University of Washington Astronomy Department and Astrobiology Program , Seattle, Washington, USA
| | - Dimitra Atri
- 13 Blue Marble Space Institute of Science , Seattle, Washington, USA
| | | | - Jeff S Bowman
- 19 Lamont-Doherty Earth Observatory, Columbia University , Palisades, New York, USA
| | | | | | - Regina Carns
- 22 Polar Science Center, Applied Physics Laboratory, University of Washington , Seattle, Washington, USA
| | - Aditya Chopra
- 23 Planetary Science Institute, Research School of Earth Sciences, Research School of Astronomy and Astrophysics, The Australian National University , Canberra, Australia
| | - Jesse Colangelo-Lillis
- 24 Earth and Planetary Science, McGill University , and the McGill Space Institute, Montréal, Canada
| | | | - Julia DeMarines
- 13 Blue Marble Space Institute of Science , Seattle, Washington, USA
| | | | - Carie Frantz
- 27 Department of Geosciences, Weber State University , Ogden, Utah, USA
| | - Eduardo de la Fuente
- 28 IAM-Departamento de Fisica, CUCEI , Universidad de Guadalajara, Guadalajara, México
| | - Douglas Galante
- 29 Brazilian Synchrotron Light Laboratory , Campinas, Brazil
| | - Jennifer Glass
- 30 School of Earth and Atmospheric Sciences, Georgia Institute of Technology , Atlanta, Georgia , USA
| | | | | | - Colin Goldblatt
- 33 School of Earth and Ocean Sciences, University of Victoria , Victoria, Canada
| | - Rachel Horak
- 34 American Society for Microbiology , Washington, DC, USA
| | | | - Betül Kaçar
- 36 Harvard University , Organismic and Evolutionary Biology, Cambridge, Massachusetts, USA
| | - Akos Kereszturi
- 37 Research Centre for Astronomy and Earth Sciences , Hungarian Academy of Sciences, Budapest, Hungary
| | - Emily Knowles
- 38 Johnson & Wales University , Denver, Colorado, USA
| | - Paul Mayeur
- 39 Rensselaer Polytechnic Institute , Troy, New York, USA
| | - Shawn McGlynn
- 40 Earth Life Science Institute, Tokyo Institute of Technology , Tokyo, Japan
| | - Yamila Miguel
- 41 Laboratoire Lagrange, UMR 7293, Université Nice Sophia Antipolis , CNRS, Observatoire de la Côte d'Azur, Nice, France
| | | | - Catherine Neish
- 43 Department of Earth Sciences, The University of Western Ontario , London, Canada
| | - Lena Noack
- 44 Royal Observatory of Belgium , Brussels, Belgium
| | - Sarah Rugheimer
- 45 Department of Astronomy, Harvard University , Cambridge, Massachusetts, USA
- 46 University of St. Andrews , St. Andrews, UK
| | - Eva E Stüeken
- 47 University of Washington , Seattle, Washington, USA
- 48 University of California , Riverside, California, USA
| | | | - Sara Imari Walker
- 13 Blue Marble Space Institute of Science , Seattle, Washington, USA
- 50 School of Earth and Space Exploration and Beyond Center for Fundamental Concepts in Science, Arizona State University , Tempe, Arizona, USA
| | - Teresa Wong
- 51 Department of Earth and Planetary Sciences, Washington University in St. Louis , St. Louis, Missouri, USA
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Barnes JW, Quarles B, Lissauer JJ, Chambers J, Hedman MM. Obliquity Variability of a Potentially Habitable Early Venus. ASTROBIOLOGY 2016; 16:487-499. [PMID: 27328026 DOI: 10.1089/ast.2015.1427] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
UNLABELLED Venus currently rotates slowly, with its spin controlled by solid-body and atmospheric thermal tides. However, conditions may have been far different 4 billion years ago, when the Sun was fainter and most of the carbon within Venus could have been in solid form, implying a low-mass atmosphere. We investigate how the obliquity would have varied for a hypothetical rapidly rotating Early Venus. The obliquity variation structure of an ensemble of hypothetical Early Venuses is simpler than that Earth would have if it lacked its large moon (Lissauer et al., 2012 ), having just one primary chaotic regime at high prograde obliquities. We note an unexpected long-term variability of up to ±7° for retrograde Venuses. Low-obliquity Venuses show very low total obliquity variability over billion-year timescales-comparable to that of the real Moon-influenced Earth. KEY WORDS Planets and satellites-Venus. Astrobiology 16, 487-499.
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Affiliation(s)
- Jason W Barnes
- 1 Department of Physics, University of Idaho , Moscow, Idaho. Researcher ID: B-1284-2009
| | - Billy Quarles
- 2 Space Science and Astrobiology Division, NASA Ames Research Center , Moffett Field, California
- 3 Department of Physics and Physical Science, The University of Nebraska at Kearney , Kearney, Nebraska
| | - Jack J Lissauer
- 2 Space Science and Astrobiology Division, NASA Ames Research Center , Moffett Field, California
| | - John Chambers
- 4 Department of Terrestrial Magnetism, Carnegie Institution of Washington , Washington, DC
| | - Matthew M Hedman
- 1 Department of Physics, University of Idaho , Moscow, Idaho. Researcher ID: B-1284-2009
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Shields AL, Barnes R, Agol E, Charnay B, Bitz C, Meadows VS. The Effect of Orbital Configuration on the Possible Climates and Habitability of Kepler-62f. ASTROBIOLOGY 2016; 16:443-64. [PMID: 27176715 PMCID: PMC4900229 DOI: 10.1089/ast.2015.1353] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 02/21/2016] [Indexed: 05/21/2023]
Abstract
UNLABELLED As lower-mass stars often host multiple rocky planets, gravitational interactions among planets can have significant effects on climate and habitability over long timescales. Here we explore a specific case, Kepler-62f (Borucki et al., 2013 ), a potentially habitable planet in a five-planet system with a K2V host star. N-body integrations reveal the stable range of initial eccentricities for Kepler-62f is 0.00 ≤ e ≤ 0.32, absent the effect of additional, undetected planets. We simulate the tidal evolution of Kepler-62f in this range and find that, for certain assumptions, the planet can be locked in a synchronous rotation state. Simulations using the 3-D Laboratoire de Météorologie Dynamique (LMD) Generic global climate model (GCM) indicate that the surface habitability of this planet is sensitive to orbital configuration. With 3 bar of CO2 in its atmosphere, we find that Kepler-62f would only be warm enough for surface liquid water at the upper limit of this eccentricity range, providing it has a high planetary obliquity (between 60° and 90°). A climate similar to that of modern-day Earth is possible for the entire range of stable eccentricities if atmospheric CO2 is increased to 5 bar levels. In a low-CO2 case (Earth-like levels), simulations with version 4 of the Community Climate System Model (CCSM4) GCM and LMD Generic GCM indicate that increases in planetary obliquity and orbital eccentricity coupled with an orbital configuration that places the summer solstice at or near pericenter permit regions of the planet with above-freezing surface temperatures. This may melt ice sheets formed during colder seasons. If Kepler-62f is synchronously rotating and has an ocean, CO2 levels above 3 bar would be required to distribute enough heat to the nightside of the planet to avoid atmospheric freeze-out and permit a large enough region of open water at the planet's substellar point to remain stable. Overall, we find multiple plausible combinations of orbital and atmospheric properties that permit surface liquid water on Kepler-62f. KEY WORDS Extrasolar planets-Habitability-Planetary environments. Astrobiology 16, 443-464.
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Affiliation(s)
- Aomawa L Shields
- 1 NSF Astronomy and Astrophysics Postdoctoral Fellow, UC President's Postdoctoral Program Fellow, Department of Physics and Astronomy, University of California , Los Angeles, and Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts
| | - Rory Barnes
- 2 Department of Astronomy and Astrobiology Program, University of Washington , Seattle, Washington
| | - Eric Agol
- 2 Department of Astronomy and Astrobiology Program, University of Washington , Seattle, Washington
| | - Benjamin Charnay
- 2 Department of Astronomy and Astrobiology Program, University of Washington , Seattle, Washington
| | - Cecilia Bitz
- 3 Department of Atmospheric Sciences, University of Washington , Seattle, Washington
| | - Victoria S Meadows
- 2 Department of Astronomy and Astrobiology Program, University of Washington , Seattle, Washington
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Cockell CS, Bush T, Bryce C, Direito S, Fox-Powell M, Harrison JP, Lammer H, Landenmark H, Martin-Torres J, Nicholson N, Noack L, O'Malley-James J, Payler SJ, Rushby A, Samuels T, Schwendner P, Wadsworth J, Zorzano MP. Habitability: A Review. ASTROBIOLOGY 2016; 16:89-117. [PMID: 26741054 DOI: 10.1089/ast.2015.1295] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Habitability is a widely used word in the geoscience, planetary science, and astrobiology literature, but what does it mean? In this review on habitability, we define it as the ability of an environment to support the activity of at least one known organism. We adopt a binary definition of "habitability" and a "habitable environment." An environment either can or cannot sustain a given organism. However, environments such as entire planets might be capable of supporting more or less species diversity or biomass compared with that of Earth. A clarity in understanding habitability can be obtained by defining instantaneous habitability as the conditions at any given time in a given environment required to sustain the activity of at least one known organism, and continuous planetary habitability as the capacity of a planetary body to sustain habitable conditions on some areas of its surface or within its interior over geological timescales. We also distinguish between surface liquid water worlds (such as Earth) that can sustain liquid water on their surfaces and interior liquid water worlds, such as icy moons and terrestrial-type rocky planets with liquid water only in their interiors. This distinction is important since, while the former can potentially sustain habitable conditions for oxygenic photosynthesis that leads to the rise of atmospheric oxygen and potentially complex multicellularity and intelligence over geological timescales, the latter are unlikely to. Habitable environments do not need to contain life. Although the decoupling of habitability and the presence of life may be rare on Earth, it may be important for understanding the habitability of other planetary bodies.
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Affiliation(s)
- C S Cockell
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - T Bush
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - C Bryce
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - S Direito
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - M Fox-Powell
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - J P Harrison
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - H Lammer
- 2 Austrian Academy of Sciences, Space Research Institute , Graz, Austria
| | - H Landenmark
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - J Martin-Torres
- 3 Division of Space Technology, Department of Computer Science, Electrical and Space Engineering, Luleå University of Technology , Kiruna, Sweden; and Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR), Armilla, Granada, Spain
| | - N Nicholson
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - L Noack
- 4 Department of Reference Systems and Planetology, Royal Observatory of Belgium , Brussels, Belgium
| | - J O'Malley-James
- 5 School of Physics and Astronomy, University of St Andrews , St Andrews, UK; now at the Carl Sagan Institute, Cornell University, Ithaca, NY, USA
| | - S J Payler
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - A Rushby
- 6 Centre for Ocean and Atmospheric Science (COAS), School of Environmental Sciences, University of East Anglia , Norwich, UK
| | - T Samuels
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - P Schwendner
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - J Wadsworth
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
| | - M P Zorzano
- 3 Division of Space Technology, Department of Computer Science, Electrical and Space Engineering, Luleå University of Technology , Kiruna, Sweden; and Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR), Armilla, Granada, Spain
- 7 Centro de Astrobiología (CSIC-INTA) , Torrejón de Ardoz, Madrid, Spain
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Dressing CD, Charbonneau D. THE OCCURRENCE OF POTENTIALLY HABITABLE PLANETS ORBITING M DWARFS ESTIMATED FROM THE FULLKEPLERDATASET AND AN EMPIRICAL MEASUREMENT OF THE DETECTION SENSITIVITY. ACTA ACUST UNITED AC 2015. [DOI: 10.1088/0004-637x/807/1/45] [Citation(s) in RCA: 623] [Impact Index Per Article: 69.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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