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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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4
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Manser CJ, Gänsicke BT, Eggl S, Hollands M, Izquierdo P, Koester D, Landstreet JD, Lyra W, Marsh TR, Meru F, Mustill AJ, Rodríguez-Gil P, Toloza O, Veras D, Wilson DJ, Burleigh MR, Davies MB, Farihi J, Gentile Fusillo N, de Martino D, Parsons SG, Quirrenbach A, Raddi R, Reffert S, Del Santo M, Schreiber MR, Silvotti R, Toonen S, Villaver E, Wyatt M, Xu S, Portegies Zwart S. A planetesimal orbiting within the debris disc around a white dwarf star. Science 2019; 364:66-69. [PMID: 30948547 DOI: 10.1126/science.aat5330] [Citation(s) in RCA: 115] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 02/26/2019] [Indexed: 12/30/2022]
Abstract
Many white dwarf stars show signs of having accreted smaller bodies, implying that they may host planetary systems. A small number of these systems contain gaseous debris discs, visible through emission lines. We report a stable 123.4-minute periodic variation in the strength and shape of the Ca ii emission line profiles originating from the debris disc around the white dwarf SDSS J122859.93+104032.9. We interpret this short-period signal as the signature of a solid-body planetesimal held together by its internal strength.
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Affiliation(s)
| | - Boris T Gänsicke
- Department of Physics, University of Warwick, Coventry CV4 7AL, UK.,Centre for Exoplanets and Habitability, University of Warwick, Coventry CV4 7AL, UK
| | - Siegfried Eggl
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
| | - Mark Hollands
- Department of Physics, University of Warwick, Coventry CV4 7AL, UK
| | - Paula Izquierdo
- Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife, Spain.,Departamento de Astrofísica, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Spain
| | - Detlev Koester
- Institut für Theoretische Physik und Astrophysik, Universität Kiel, 24098 Kiel, Germany
| | - John D Landstreet
- Department of Physics and Astronomy, The University of Western Ontario, London, Ontario, N6A 3K7, Canada.,Armagh Observatory and Planetarium, College Hill, Armagh, Co. Armagh BT61 9DG, UK
| | - Wladimir Lyra
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA.,Department of Physics and Astronomy, California State University, Northridge, 18111 Nordhoff St., Northridge, CA 91330, USA
| | - Thomas R Marsh
- Department of Physics, University of Warwick, Coventry CV4 7AL, UK
| | - Farzana Meru
- Department of Physics, University of Warwick, Coventry CV4 7AL, UK
| | - Alexander J Mustill
- Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, SE-221 00 Lund, Sweden
| | - Pablo Rodríguez-Gil
- Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife, Spain.,Departamento de Astrofísica, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Spain
| | - Odette Toloza
- Department of Physics, University of Warwick, Coventry CV4 7AL, UK
| | - Dimitri Veras
- Department of Physics, University of Warwick, Coventry CV4 7AL, UK.,Centre for Exoplanets and Habitability, University of Warwick, Coventry CV4 7AL, UK
| | - David J Wilson
- Department of Physics, University of Warwick, Coventry CV4 7AL, UK.,McDonald Observatory, University of Texas at Austin, Austin, TX 78712, USA
| | - Matthew R Burleigh
- Department of Physics and Astronomy, Leicester Institute of Space and Earth Observation, University of Leicester, University Road, Leicester LE1 7RH, UK
| | - Melvyn B Davies
- Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, SE-221 00 Lund, Sweden
| | - Jay Farihi
- Physics and Astronomy, University College London, London WC1E 6BT, UK
| | | | - Domitilla de Martino
- Osservatorio Astronomico di Capodimonte, National Institute for Astrophysics, Via Moiarello 16, 80131 Napoli, Italy
| | - Steven G Parsons
- Department of Physics and Astronomy, The University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Andreas Quirrenbach
- Landessternwarte, Zentrum für Astronomie der Universität Heidelberg, Königstuhl 12, 69117 Heidelberg, Germany
| | - Roberto Raddi
- Dr. Karl Remeis-Sternwarte, Astronomisches Institut der Universität Erlangen-Nürnberg, Sternwartestr. 7, 96049, Bamberg, Germany
| | - Sabine Reffert
- Landessternwarte, Zentrum für Astronomie der Universität Heidelberg, Königstuhl 12, 69117 Heidelberg, Germany
| | - Melania Del Santo
- National Institute for Astrophysics/Institute of Space Astrophysics and Cosmic Physics, via Ugo La Malfa 153, 90146, Palermo, Italy
| | - Matthias R Schreiber
- Instituto de Física y Astronomía, Universidad de Valparaíso, Av. Gran Bretaña 1111, 5030 Casilla, Valparaíso, Chile.,Milennium Nucleus for Planet Formation - NPF, Universidad de Valparaíso, Av. Gran Bretaña 1111, Valparaíso, Chile
| | - Roberto Silvotti
- National Institute for Astrophysics, Osservatorio Astrofisico di Torino, Strada dell'Osservatorio 20, 10025 Pino Torinese, Italy
| | - Silvia Toonen
- Anton Pannekoek Instituut voor Sterrenkunde, University of Amsterdam, P.O. Box 94249, 1090 GE, Amsterdam, Netherlands
| | - Eva Villaver
- Departamento de Física Teórica, Universidad Autónoma de Madrid, Cantoblanco 28049 Madrid, Spain
| | - Mark Wyatt
- Institute of Astronomy, Madingley Rd, Cambridge CB3 0HA, UK
| | - Siyi Xu
- Gemini Observatory, Northern Operations Center, 670 N. A'ohoku Place, Hilo, HI 96720, USA
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5
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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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