A Terminology and Quantitative Framework for Assessing the Habitability of Solar System and Extraterrestrial Worlds
The search for extraterrestrial life in the solar system and beyond is a key science driver in astrobiology, planetary science, and astrophysics. A critical step is the identification and characterization of potential habitats, both to guide the search and to interpret its results. However, a well-a...
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2025-01-01
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| Series: | The Planetary Science Journal |
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| Online Access: | https://doi.org/10.3847/PSJ/addda8 |
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| author | Dániel Apai Rory Barnes Matthew M. Murphy Tim Lichtenberg Noah Tuchow Régis Ferrière Kevin Wagner Antonin Affholder Renu Malhotra Baptiste Journaux Allona Vazan Ramses Ramirez Abel Méndez Stephen R. Kane Veronica H. Klawender NExSS Quantitative Habitability Science Working Group |
| author_facet | Dániel Apai Rory Barnes Matthew M. Murphy Tim Lichtenberg Noah Tuchow Régis Ferrière Kevin Wagner Antonin Affholder Renu Malhotra Baptiste Journaux Allona Vazan Ramses Ramirez Abel Méndez Stephen R. Kane Veronica H. Klawender NExSS Quantitative Habitability Science Working Group |
| author_sort | Dániel Apai |
| collection | DOAJ |
| description | The search for extraterrestrial life in the solar system and beyond is a key science driver in astrobiology, planetary science, and astrophysics. A critical step is the identification and characterization of potential habitats, both to guide the search and to interpret its results. However, a well-accepted, self-consistent, flexible, and quantitative terminology and method of assessment of habitability are lacking. Our paper fills this gap based on a 3 yr long study by the NExSS Quantitative Habitability Science Working Group. We review past studies of habitability but find that the lack of a universally valid definition of life prohibits a universally applicable definition of habitability. A more nuanced approach is needed. We introduce a quantitative habitability assessment framework that enables self-consistent, probabilistic assessment of the compatibility of two models: first, a habitat model, which describes the probability distributions of key conditions in the habitat, and second, a viability model, which describes the probability that a metabolism is viable given a set of environmental conditions. We provide an open-source implementation of this framework and four examples as a proof of concept: (a) comparison of two exoplanets for observational target prioritization, (b) interpretation of atmospheric O _2 detection in two exoplanets, (c) subsurface habitability of Mars, and (d) ocean habitability in Europa. These examples demonstrate that our framework can self-consistently inform astrobiology research over a broad range of questions. The proposed framework is modular so that future work can expand the range and complexity of models available, both for habitats and for metabolisms. |
| format | Article |
| id | doaj-art-7ec7502f3a4a4a49b86a33521435e71e |
| institution | DOAJ |
| issn | 2632-3338 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Planetary Science Journal |
| spelling | doaj-art-7ec7502f3a4a4a49b86a33521435e71e2025-08-20T03:13:03ZengIOP PublishingThe Planetary Science Journal2632-33382025-01-016716510.3847/PSJ/addda8A Terminology and Quantitative Framework for Assessing the Habitability of Solar System and Extraterrestrial WorldsDániel Apai0https://orcid.org/0000-0003-3714-5855Rory Barnes1https://orcid.org/0000-0001-6487-5445Matthew M. Murphy2https://orcid.org/0000-0002-8517-8857Tim Lichtenberg3https://orcid.org/0000-0002-3286-7683Noah Tuchow4https://orcid.org/0000-0003-3989-5545Régis Ferrière5https://orcid.org/0000-0002-5806-5566Kevin Wagner6https://orcid.org/0000-0002-4309-6343Antonin Affholder7https://orcid.org/0000-0003-3481-0952Renu Malhotra8https://orcid.org/0000-0002-1226-3305Baptiste Journaux9https://orcid.org/0000-0002-0957-3177Allona Vazan10https://orcid.org/0000-0001-9504-3174Ramses Ramirez11https://orcid.org/0000-0001-7553-8444Abel Méndez12https://orcid.org/0000-0003-0726-0748Stephen R. Kane13https://orcid.org/0000-0002-7084-0529Veronica H. Klawender14NExSS Quantitative Habitability Science Working GroupSteward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721, USA ; apai@arizona.edu; Lunar and Planetary Laboratory, University of Arizona , 1629 East University Boulevard, Tucson, AZ 85721, USA; Alien Earths Team , NASA ICAR/NExSS, USAAstronomy Department, University of Washington , Box 951580, Seattle, WA 98195, USASteward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721, USA ; apai@arizona.edu; Alien Earths Team , NASA ICAR/NExSS, USAAlien Earths Team , NASA ICAR/NExSS, USA; Kapteyn Astronomical Institute, University of Groningen , P.O. Box 800, NL-9700 AV Groningen, The NetherlandsNASA Goddard Space Flight Center , Greenbelt, MD, USAAlien Earths Team , NASA ICAR/NExSS, USA; Institut de Biologie de l’École Normale Supérieure École Normale Supérieure, Université Paris Sciences et Lettres , 46 Rue d’Ulm, F-75005 Paris, France; International Research Laboratory for Interdisciplinary Global Environmental Studies (iGLOBES) CNRS, ENS, Université Paris Sciences et Lettres, University of Arizona , Tucson, AZ, USA; Department of Ecology and Evolutionary Biology, University of Arizona, Tucson , AZ, USASteward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721, USA ; apai@arizona.eduAlien Earths Team , NASA ICAR/NExSS, USA; Department of Ecology and Evolutionary Biology, University of Arizona, Tucson , AZ, USALunar and Planetary Laboratory, University of Arizona , 1629 East University Boulevard, Tucson, AZ 85721, USADepartment of Earth and Space Science, University of Washington , Box 951310, Seattle, WA 98195, USAAstrophysics Research Center (ARCO), Department of Natural Sciences, The Open University of Israel , Raanana 4353701, IsraelUniversity of Central Florida , Department of Physics, Planetary Sciences Group, Orlando, Fl 32816, USAPlanetary Habitability Laboratory, University of Puerto Rico at Arecibo , USADepartment of Earth and Planetary Sciences, University of California , Riverside, CA 92521, USASteward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721, USA ; apai@arizona.eduThe search for extraterrestrial life in the solar system and beyond is a key science driver in astrobiology, planetary science, and astrophysics. A critical step is the identification and characterization of potential habitats, both to guide the search and to interpret its results. However, a well-accepted, self-consistent, flexible, and quantitative terminology and method of assessment of habitability are lacking. Our paper fills this gap based on a 3 yr long study by the NExSS Quantitative Habitability Science Working Group. We review past studies of habitability but find that the lack of a universally valid definition of life prohibits a universally applicable definition of habitability. A more nuanced approach is needed. We introduce a quantitative habitability assessment framework that enables self-consistent, probabilistic assessment of the compatibility of two models: first, a habitat model, which describes the probability distributions of key conditions in the habitat, and second, a viability model, which describes the probability that a metabolism is viable given a set of environmental conditions. We provide an open-source implementation of this framework and four examples as a proof of concept: (a) comparison of two exoplanets for observational target prioritization, (b) interpretation of atmospheric O _2 detection in two exoplanets, (c) subsurface habitability of Mars, and (d) ocean habitability in Europa. These examples demonstrate that our framework can self-consistently inform astrobiology research over a broad range of questions. The proposed framework is modular so that future work can expand the range and complexity of models available, both for habitats and for metabolisms.https://doi.org/10.3847/PSJ/addda8AstrobiologyHabitable planetsMarsEuropaHabitable zoneBiosignatures |
| spellingShingle | Dániel Apai Rory Barnes Matthew M. Murphy Tim Lichtenberg Noah Tuchow Régis Ferrière Kevin Wagner Antonin Affholder Renu Malhotra Baptiste Journaux Allona Vazan Ramses Ramirez Abel Méndez Stephen R. Kane Veronica H. Klawender NExSS Quantitative Habitability Science Working Group A Terminology and Quantitative Framework for Assessing the Habitability of Solar System and Extraterrestrial Worlds The Planetary Science Journal Astrobiology Habitable planets Mars Europa Habitable zone Biosignatures |
| title | A Terminology and Quantitative Framework for Assessing the Habitability of Solar System and Extraterrestrial Worlds |
| title_full | A Terminology and Quantitative Framework for Assessing the Habitability of Solar System and Extraterrestrial Worlds |
| title_fullStr | A Terminology and Quantitative Framework for Assessing the Habitability of Solar System and Extraterrestrial Worlds |
| title_full_unstemmed | A Terminology and Quantitative Framework for Assessing the Habitability of Solar System and Extraterrestrial Worlds |
| title_short | A Terminology and Quantitative Framework for Assessing the Habitability of Solar System and Extraterrestrial Worlds |
| title_sort | terminology and quantitative framework for assessing the habitability of solar system and extraterrestrial worlds |
| topic | Astrobiology Habitable planets Mars Europa Habitable zone Biosignatures |
| url | https://doi.org/10.3847/PSJ/addda8 |
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