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Phillips MS, Moersch JE, Cabrol NA, Candela A, Wettergreen D, Warren-Rhodes K, Hinman NW. Planetary Mapping Using Deep Learning: A Method to Evaluate Feature Identification Confidence Applied to Habitats in Mars-Analog Terrain. ASTROBIOLOGY 2023; 23:76-93. [PMID: 36520604 DOI: 10.1089/ast.2022.0014] [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: 06/17/2023]
Abstract
The goals of Mars exploration are evolving beyond describing environmental habitability at global and regional scales to targeting specific locations for biosignature detection, sample return, and eventual human exploration. An increase in the specificity of scientific goals-from follow the water to find the biosignatures-requires parallel developments in strategies that translate terrestrial Mars-analog research into confident identification of rover-explorable targets on Mars. Precisely how to integrate terrestrial, ground-based analyses with orbital data sets and transfer those lessons into rover-relevant search strategies for biosignatures on Mars remains an open challenge. Here, leveraging small Unmanned Aerial System (sUAS) technology and state-of-the-art fully convolutional neural networks for pixel-wise classification, we present an end-to-end methodology that applies Deep Learning to map geomorphologic units and quantify feature identification confidence. We used this method to assess the identification confidence of rover-explorable habitats in the Mars-analog Salar de Pajonales over a range of spatial resolutions and found that spatial resolutions two times better than are available from Mars would be necessary to identify habitats in this study at the 1-σ (85%) confidence level. The approach we present could be used to compare the identifiability of habitats across Mars-analog environments and focus Mars exploration from the scale of regional habitability to the scale of specific habitats. Our methods could also be adapted to map dome- and ridge-like features on the surface of Mars to further understand their origin and astrobiological potential.
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Affiliation(s)
- Michael S Phillips
- Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA
| | - Jeffrey E Moersch
- Department of Earth and Planetary Sciences, The University of Tennessee, Knoxville, Tennessee, USA
| | - Nathalie A Cabrol
- SETI Institute/NASA Ames Research Center, Moffett Field, California, USA
| | - Alberto Candela
- The Robotics Institute, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
| | - David Wettergreen
- The Robotics Institute, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
| | | | - Nancy W Hinman
- Department of Geosciences, University of Montana, Missoula, Montana, USA
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2
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Cockell CS. Are microorganisms everywhere they can be? Environ Microbiol 2021; 23:6355-6363. [PMID: 34693610 DOI: 10.1111/1462-2920.15825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 10/15/2021] [Indexed: 11/27/2022]
Abstract
Baas-Becking is famously attributed with the conjecture that 'everything is everywhere, but the environment selects'. Although this aphorism is largely challenged by microbial biogeographical data, even weak versions of the claim leave unanswered the question about whether all environments that could theoretically support life contain life. In the last decade, the discovery of thermally sterilized habitable environments disconnected from inhabited regions, and habitats within organisms such as the sterile, but habitable human fetal gut, suggest the existence of a diversity of macroscopic habitable environments apparently devoid of actively metabolizing or reproducing life. Less clear is the status of such environments at the micron scale, for example, between colonies of organisms within rock interstices or on and within other substrates. I discuss recent evidence for these types of environments. These environments have practical uses in: (i) being negative controls for understanding the role of microbial processes in geochemical cycles and geological processes, (ii) yielding insights into the extent to which the biosphere extends into all spaces it theoretically can, (iii) suggesting caution in interpreting the results of life detection instrumentation, and (iv) being useful for establishing the conditions for the origin of life and its prevalence on other planetary bodies.
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Affiliation(s)
- Charles S Cockell
- UK Centre for Astrobiology, School of Physics and Astronomy, James Clerk Maxwell Building, The King's Buildings, University of Edinburgh, Edinburgh, EH9 3JZ, UK
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Baucon A, Neto de Carvalho C, Briguglio A, Piazza M, Felletti F. A predictive model for the ichnological suitability of the Jezero crater, Mars: searching for fossilized traces of life-substrate interactions in the 2020 Rover Mission Landing Site. PeerJ 2021; 9:e11784. [PMID: 34631304 PMCID: PMC8466086 DOI: 10.7717/peerj.11784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 06/24/2021] [Indexed: 11/20/2022] Open
Abstract
Ichnofossils, the fossilized products of life-substrate interactions, are among the most abundant biosignatures on Earth and therefore they may provide scientific evidence of potential life that may have existed on Mars. Ichnofossils offer unique advantages in the search for extraterrestrial life, including the fact that they are resilient to processes that obliterate other evidence for past life, such as body fossils, as well as chemical and isotopic biosignatures. The goal of this paper is evaluating the suitability of the Mars 2020 Landing Site for ichnofossils. To this goal, we apply palaeontological predictive modelling, a technique used to forecast the location of fossil sites in uninvestigated areas on Earth. Accordingly, a geographic information system (GIS) of the landing site is developed. Each layer of the GIS maps the suitability for one or more ichnofossil types (bioturbation, bioerosion, biostratification structures) based on an assessment of a single attribute (suitability factor) of the Martian environment. Suitability criteria have been selected among the environmental attributes that control ichnofossil abundance and preservation in 18 reference sites on Earth. The goal of this research is delivered through three predictive maps showing which areas of the Mars 2020 Landing Site are more likely to preserve potential ichnofossils. On the basis of these maps, an ichnological strategy for the Perseverance rover is identified, indicating (1) 10 sites on Mars with high suitability for bioturbation, bioerosion and biostratification ichnofossils, (2) the ichnofossil types, if any, that are more likely to be present at each site, (3) the most efficient observation strategy for detecting eventual ichnofossils. The predictive maps and the ichnological strategy can be easily integrated in the existing plans for the exploration of the Jezero crater, realizing benefits in life-search efficiency and cost-reduction.
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Affiliation(s)
- Andrea Baucon
- DISTAV, University of Genoa, Genova, Italy.,Geology Office of Idanha-a-Nova, Naturtejo UNESCO Global Geopark, Idanha-a-Nova, Portugal
| | - Carlos Neto de Carvalho
- Geology Office of Idanha-a-Nova, Naturtejo UNESCO Global Geopark, Idanha-a-Nova, Portugal.,Instituto D. Luiz, Faculdade de Ciências da Universidade de Lisboa, University of Lisbon, Lisbon, Portugal
| | | | | | - Fabrizio Felletti
- Dipartimento di Scienze della Terra 'Ardito Desio', University of Milan, Milan, Italy
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Limaye SS, Mogul R, Baines KH, Bullock MA, Cockell C, Cutts JA, Gentry DM, Grinspoon DH, Head JW, Jessup KL, Kompanichenko V, Lee YJ, Mathies R, Milojevic T, Pertzborn RA, Rothschild L, Sasaki S, Schulze-Makuch D, Smith DJ, Way MJ. Venus, an Astrobiology Target. ASTROBIOLOGY 2021; 21:1163-1185. [PMID: 33970019 DOI: 10.1089/ast.2020.2268] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We present a case for the exploration of Venus as an astrobiology target-(1) investigations focused on the likelihood that liquid water existed on the surface in the past, leading to the potential for the origin and evolution of life, (2) investigations into the potential for habitable zones within Venus' present-day clouds and Venus-like exo atmospheres, (3) theoretical investigations into how active aerobiology may impact the radiative energy balance of Venus' clouds and Venus-like atmospheres, and (4) application of these investigative approaches toward better understanding the atmospheric dynamics and habitability of exoplanets. The proximity of Venus to Earth, guidance for exoplanet habitability investigations, and access to the potential cloud habitable layer and surface for prolonged in situ extended measurements together make the planet a very attractive target for near term astrobiological exploration.
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Affiliation(s)
- Sanjay S Limaye
- Space Science and Engineering Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Rakesh Mogul
- Chemistry and Biochemistry Department, Cal Poly Pomona, Pomona, California, USA
| | - Kevin H Baines
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | | | - Charles Cockell
- School of Physics and Astronomy, University of Edinburgh, Edinburgh, Scotland
| | - James A Cutts
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Diana M Gentry
- NASA Ames Research Center, Moffett Field, California, USA
| | | | - James W Head
- Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, Rhode Island, USA
| | | | - Vladimir Kompanichenko
- Institute for Complex Analysis of Regional Problems, Russian Academy of Sciences, Birobidzhan, Russia
| | - Yeon Joo Lee
- Zentrum für Astronomie und Astrophysik, Technical University of Berlin, Berlin, Germany
| | - Richard Mathies
- Chemistry Department and Space Sciences Lab, University of California, Berkeley, Berkeley, California, USA
| | - Tetyana Milojevic
- Department of Biophysical Chemistry, University of Vienna, Vienna, Austria
| | - Rosalyn A Pertzborn
- Space Science and Engineering Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | | | - Satoshi Sasaki
- School of Health Sciences, Tokyo University of Technology, Hachioji, Japan
| | - Dirk Schulze-Makuch
- Center for Astronomy and Astrophysics (ZAA), Technische Universität Berlin, Berlin, Germany
- German Research Centre for Geosciences (GFZ), Potsdam, Germany
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin, Germany
| | - David J Smith
- NASA Ames Research Center, Moffett Field, California, USA
| | - Michael J Way
- NASA Goddard Institute for Space Studies, New York, New York, USA
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Osinski G, Cockell C, Pontefract A, Sapers H. The Role of Meteorite Impacts in the Origin of Life. ASTROBIOLOGY 2020; 20:1121-1149. [PMID: 32876492 PMCID: PMC7499892 DOI: 10.1089/ast.2019.2203] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The conditions, timing, and setting for the origin of life on Earth and whether life exists elsewhere in our solar system and beyond represent some of the most fundamental scientific questions of our time. Although the bombardment of planets and satellites by asteroids and comets has long been viewed as a destructive process that would have presented a barrier to the emergence of life and frustrated or extinguished life, we provide a comprehensive synthesis of data and observations on the beneficial role of impacts in a wide range of prebiotic and biological processes. In the context of previously proposed environments for the origin of life on Earth, we discuss how meteorite impacts can generate both subaerial and submarine hydrothermal vents, abundant hydrothermal-sedimentary settings, and impact analogues for volcanic pumice rafts and splash pools. Impact events can also deliver and/or generate many of the necessary chemical ingredients for life and catalytic substrates such as clays as well. The role that impact cratering plays in fracturing planetary crusts and its effects on deep subsurface habitats for life are also discussed. In summary, we propose that meteorite impact events are a fundamental geobiological process in planetary evolution that played an important role in the origin of life on Earth. We conclude with the recommendation that impact craters should be considered prime sites in the search for evidence of past life on Mars. Furthermore, unlike other geological processes such as volcanism or plate tectonics, impact cratering is ubiquitous on planetary bodies throughout the Universe and is independent of size, composition, and distance from the host star. Impact events thus provide a mechanism with the potential to generate habitable planets, moons, and asteroids throughout the Solar System and beyond.
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Affiliation(s)
- G.R. Osinski
- Institute for Earth and Space Exploration, University of Western Ontario, London, Canada
- Department of Earth Sciences, University of Western Ontario, London, Canada
- Address correspondence to: Dr. Gordon Osinski, Department of Earth Sciences, 1151 Richmond Street, University of Western Ontario, London ON, N6A 5B7, Canada
| | - C.S. Cockell
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
| | - A. Pontefract
- Department of Biology, Georgetown University, Washington, DC, USA
| | - H.M. Sapers
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA
- Department of Earth Sciences, University of Southern California, Los Angeles, California, USA
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Fox-Powell MG, Hallsworth JE, Cousins CR, Cockell CS. Ionic Strength Is a Barrier to the Habitability of Mars. ASTROBIOLOGY 2016; 16:427-42. [PMID: 27213516 DOI: 10.1089/ast.2015.1432] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
UNLABELLED The thermodynamic availability of water (water activity) strictly limits microbial propagation on Earth, particularly in hypersaline environments. A considerable body of evidence indicates the existence of hypersaline surface waters throughout the history of Mars; therefore it is assumed that, as on Earth, water activity is a major limiting factor for martian habitability. However, the differing geological histories of Earth and Mars have driven variations in their respective aqueous geochemistry, with as-yet-unknown implications for habitability. Using a microbial community enrichment approach, we investigated microbial habitability for a suite of simulated martian brines. While the habitability of some martian brines was consistent with predictions made from water activity, others were uninhabitable even when the water activity was biologically permissive. We demonstrate experimentally that high ionic strength, driven to extremes on Mars by the ubiquitous occurrence of multivalent ions, renders these environments uninhabitable despite the presence of biologically available water. These findings show how the respective geological histories of Earth and Mars, which have produced differences in the planets' dominant water chemistries, have resulted in different physicochemical extremes which define the boundary space for microbial habitability. KEY WORDS Habitability-Mars-Salts-Water activity-Life in extreme environments. Astrobiology 16, 427-442.
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Affiliation(s)
- Mark G Fox-Powell
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , UK
| | - John E Hallsworth
- 2 Institute for Global Food Security, Queen's University Belfast , UK
| | - Claire R Cousins
- 3 Department of Earth and Environmental Sciences, University of St. Andrews , UK
| | - Charles S Cockell
- 1 UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh , UK
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Jones EG, Lineweaver CH, Clarke JD. An extensive phase space for the potential martian biosphere. ASTROBIOLOGY 2011; 11:1017-1033. [PMID: 22149914 DOI: 10.1089/ast.2011.0660] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We present a comprehensive model of martian pressure-temperature (P-T) phase space and compare it with that of Earth. Martian P-T conditions compatible with liquid water extend to a depth of ∼310 km. We use our phase space model of Mars and of terrestrial life to estimate the depths and extent of the water on Mars that is habitable for terrestrial life. We find an extensive overlap between inhabited terrestrial phase space and martian phase space. The lower martian surface temperatures and shallower martian geotherm suggest that, if there is a hot deep biosphere on Mars, it could extend 7 times deeper than the ∼5 km depth of the hot deep terrestrial biosphere in the crust inhabited by hyperthermophilic chemolithotrophs. This corresponds to ∼3.2% of the volume of present-day Mars being potentially habitable for terrestrial-like life.
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Affiliation(s)
- Eriita G Jones
- Planetary Sciences Institute, Research School of Astronomy and Astrophysics and the Research School of Earth Sciences, Australian National University, Canberra, Australia.
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Cockell CS. Life in the lithosphere, kinetics and the prospects for life elsewhere. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2011; 369:516-537. [PMID: 21220278 DOI: 10.1098/rsta.2010.0232] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The global contiguity of life on the Earth today is a result of the high flux of carbon and oxygen from oxygenic photosynthesis over the planetary surface and its use in aerobic respiration. Life's ability to directly use redox couples from components of the planetary lithosphere in a pre-oxygenic photosynthetic world can be investigated by studying the distribution of organisms that use energy sources normally bound within rocks, such as iron. Microbiological data from Iceland and the deep oceans show the kinetic limitations of living directly off igneous rocks in the lithosphere. Using energy directly extracted from rocks the lithosphere will support about six orders of magnitude less productivity than the present-day Earth, and it would be highly localized. Paradoxically, the biologically extreme conditions of the interior of a planet and the inimical conditions of outer space, between which life is trapped, are the locations from which volcanism and impact events, respectively, originate. These processes facilitate the release of redox couples from the planetary lithosphere and might enable it to achieve planetary-scale productivity approximately one to two orders of magnitude lower than that produced by oxygenic photosynthesis. The significance of the detection of extra-terrestrial life is that it will allow us to test these observations elsewhere and establish an understanding of universal relationships between lithospheres and life. These data also show that the search for extra-terrestrial life must be accomplished by 'following the kinetics', which is different from following the water or energy.
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Affiliation(s)
- Charles S Cockell
- Planetary and Space Sciences Research Institute, The Open University, Milton Keynes MK7 6AA, UK.
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9
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Cockell CS. Vacant habitats in the Universe. Trends Ecol Evol 2011; 26:73-80. [DOI: 10.1016/j.tree.2010.11.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2010] [Revised: 11/13/2010] [Accepted: 11/15/2010] [Indexed: 12/14/2022]
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Jones EG, Lineweaver CH. To what extent does terrestrial life "follow the water"? ASTROBIOLOGY 2010; 10:349-361. [PMID: 20446874 DOI: 10.1089/ast.2009.0428] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Terrestrial life is known to require liquid water, but not all terrestrial water is inhabited. Thus, liquid water is a necessary, but not sufficient, condition for life. To quantify the terrestrial limits on the habitability of water and help identify the factors that make some terrestrial water uninhabited, we present empirical pressure-temperature (P-T) phase diagrams of water, Earth, and terrestrial life. Eighty-eight percent of the volume of Earth where liquid water exists is not known to host life. This potentially uninhabited terrestrial liquid water includes (i) hot and deep regions of Earth where some combination of high temperature (T > 122 degrees C) and restrictions on pore space, nutrients, and energy is the limiting factor and (ii) cold and near-surface regions of Earth, such as brine inclusions and thin films in ice and permafrost (depths less than approximately 1 km), where low temperatures (T < -40 degrees C), low water activity (a(w) < 0.6), or both are the limiting factors. If the known limits of terrestrial life do not change significantly, these limits represent important constraints on our biosphere and, potentially, on others, since approximately 4 billion years of evolution have not allowed life to adapt to a large fraction of the volume of Earth where liquid water exists.
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Affiliation(s)
- Eriita G Jones
- Planetary Sciences Institute, Research School of Astronomy and Astrophysics and the Research School of Earth Sciences, Australian National University, Canberra, Australia.
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