A half-century of terrestrial analog studies: From craters on the Moon to searching for life on Mars

Léveillé, Richard

doi:10.1016/j.pss.2009.04.001

Cited by 34 publications

(14 citation statements)

References 62 publications

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“…Analog sites on Earth are those that share past or present characteristics with other planetary bodies, providing natural systems for study of the limits of life, which are often quite different from lab conditions ( Arndt et al, 2013 ). This concept is based on the idea that laws of physics and chemistry are universal, a principle that underlies a large proportion of astrobiology research ( Léveillé, 2010 ; Preston and Dartnell, 2014 ). Therefore, sites on Earth can provide information on how physical and chemical conditions interact to form environments conducive to life elsewhere ( Lederberg, 1960 ; Léveillé, 2010 ).…”

Section: Introductionmentioning

confidence: 99%

“…This concept is based on the idea that laws of physics and chemistry are universal, a principle that underlies a large proportion of astrobiology research ( Léveillé, 2010 ; Preston and Dartnell, 2014 ). Therefore, sites on Earth can provide information on how physical and chemical conditions interact to form environments conducive to life elsewhere ( Lederberg, 1960 ; Léveillé, 2010 ). “Extreme” environments [where conditions fall outside of the “standard” of 4–40°C, pH 5–8.5, and salinity above 37 g kg −1 water ( Kristjánsson and Hreggvidsson, 1995 ; Bartlett and Bidle, 1999 )] are common analog targets used as a way to identify and develop tools to search for identifying signs that life is or was ever present under a range of conditions ( Preston and Dartnell, 2014 ).…”

Section: Introductionmentioning

confidence: 99%

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Low Energy Subsurface Environments as Extraterrestrial Analogs

2018

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Earth’s subsurface is often isolated from phototrophic energy sources and characterized by chemotrophic modes of life. These environments are often oligotrophic and limited in electron donors or electron acceptors, and include continental crust, subseafloor oceanic crust, and marine sediment as well as subglacial lakes and the subsurface of polar desert soils. These low energy subsurface environments are therefore uniquely positioned for examining minimum energetic requirements and adaptations for chemotrophic life. Current targets for astrobiology investigations of extant life are planetary bodies with largely inhospitable surfaces, such as Mars, Europa, and Enceladus. Subsurface environments on Earth thus serve as analogs to explore possibilities of subsurface life on extraterrestrial bodies. The purpose of this review is to provide an overview of subsurface environments as potential analogs, and the features of microbial communities existing in these low energy environments, with particular emphasis on how they inform the study of energetic limits required for life. The thermodynamic energetic calculations presented here suggest that free energy yields of reactions and energy density of some metabolic redox reactions on Mars, Europa, Enceladus, and Titan could be comparable to analog environments in Earth’s low energy subsurface habitats.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Low Energy Subsurface Environments as Extraterrestrial Analogs

2018

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“…These include environmental, mineralogical, geomorphological, geochemical and biological conditions that resemble those found at present or at some point in the past on another planetary body. While each individual analogue site is not a perfect representation of the changing conditions through time of another world, the combination of analogue research with laboratory simulations and data obtained from orbiters and landers allows steps to be taken to advance our knowledge (Léveillé 2010).…”

Section: Terrestrial Analoguesmentioning

confidence: 99%

Planetary habitability: lessons learned from terrestrial analogues

Preston

Dartnell

2014

International Journal of Astrobiology

117

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Terrestrial analogue studies underpin almost all planetary missions and their use is essential in the exploration of our Solar system and in assessing the habitability of other worlds. Their value relies on the similarity of the analogue to its target, either in terms of their mineralogical or geochemical context, or current physical or chemical environmental conditions. Such analogue sites offer critical ground-truthing for astrobiological studies on the habitability of different environmental parameter sets, the biological mechanisms for survival in extreme environments and the preservation potential and detectability of biosignatures. The 33 analogue sites discussed in this review have been selected on the basis of their congruence to particular extraterrestrial locations. Terrestrial field sites that have been used most often in the literature, as well as some lesser known ones which require greater study, are incorporated to inform on the astrobiological potential of Venus, Mars, Europa, Enceladus and Titan. For example, the possibility of an aerial habitable zone on Venus has been hypothesized based on studies of life at high-altitudes in the terrestrial atmosphere. We also demonstrate why many different terrestrial analogue sites are required to satisfactorily assess the habitability of the changing environmental conditions throughout Martian history, and recommend particular sites for different epochs or potential niches. Finally, habitable zones within the aqueous environments of the icy moons of Europa and Enceladus and potentially in the hydrocarbon lakes of Titan are discussed and suitable analogue sites proposed. It is clear from this review that a number of terrestrial analogue sites can be applied to multiple planetary bodies, thereby increasing their value for astrobiological exploration. For each analogue site considered here, we summarize the pertinent physiochemical environmental features they offer and critically assess the fidelity with which they emulate their intended target locale. We also outline key issues associated with the existing documentation of analogue research and the constraints this has on the efficiency of discoveries in this field. This review thus highlights the need for a global open access database for planetary analogues.

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“…A similar inconsistency is found when we refer to Martian geology [3]. Yet, the use of these terms implies a unidirectional application of Earth geology concepts and systematics to other celestial bodies, which is particularly controversial as the Earth is always used as a reference to the rest of the cosmos, not vice versa [4]. This directionality implies a geocentric approach to planetary science, even though the Earth still remains as an extremely rare cosmological exception.…”

Section: Introductionmentioning

confidence: 63%

Cryosphere and Spatial Uniformitarianism: A New Rule for Earth and Planetary Sciences

Dobiński¹

2019

Preprint

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The lack of a uniform approach in Earth and planetary science is apparent in the current levels of inconsistency found within the research itself, the data analysis and the interpretation of results. Thus, data interpretation differ depending on whether the study refer to Earth conditions or from space. These differences are particularly pronounced for cryosphere studies, where geocentric approaches remain within ice research and its application in analogical studies. Here, the principle of spatial uniformitarianism is presented, to allow for a definitive departure from geocentrism and a proper understanding of the role of ice within both the Earth and celestial bodies. At the practical level, it may affect several geo-scientific disciplines currently inconsistent and bridging the gap among them. This rule is universal and complements the Hutton-Lyell 1795/1830 principle.

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A half-century of terrestrial analog studies: From craters on the Moon to searching for life on Mars

Cited by 34 publications

References 62 publications

Low Energy Subsurface Environments as Extraterrestrial Analogs

Low Energy Subsurface Environments as Extraterrestrial Analogs

Planetary habitability: lessons learned from terrestrial analogues

Cryosphere and Spatial Uniformitarianism: A New Rule for Earth and Planetary Sciences

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