Earth analogs for Martian life. Microbes in evaporites, a new model system for life on Mars

Rothschild, Lynn J.

doi:10.1016/0019-1035(90)90188-f

Cited by 155 publications

(75 citation statements)

References 74 publications

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“…In fact, while the sediment structure follows universal and repetitive laws (revealing in the present work a simple fractal structure, Figure 7, right), the biological structure, within the same environment, at the same meso-microscopic scales, appears to vary depending on the metabolic activity of the living organisms [38][39][40][41][42][43] (revealing in the present work a multifractal structure, Figure 5, left).…”

Section: Discussionmentioning

confidence: 47%

Microbialites at Gusev Crater, Mars.

Bianciardi

Rizzo²,

Farı́as³

et al. 2015

Astrobiol Outreach

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The Mars Exploration Rover Spirit investigated plains at Gusev crater, where sedimentary rocks are present. The Spirit rover's Athena morphological investigation shows microstructures organized in intertwined filaments of microspherules: a texture we have also found on samples of terrestrial stromatolites and other microbialites. We performed a quantitative image analysis to compare 45 microbialites samplings with 50 rover's ones (approximately 25,000/20,000 microstructures). Contours were extracted and morphometric indexes obtained: geometric and algorithmic complexities, entropy, tortuosity, minimum and maximum diameters. Terrestrial and Martian textures resulted multifractals, while terrestrial abiogenic minerals showed a simple fractal structure. Mean values and confidence intervals from the Martian images overlapped perfectly with those from terrestrial samples. The probability of this occurring by chance was less than 1/2 8 , p<0.004. Our work show the presumptive evidence of microbialites in the Martian outcroppings explored by "Spirit", confirming our previous results concerning the Martian outcroppings explored by Opportunity at Meridiani Planum: unicellular life was widespread on the ancient Mars.

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Section: Discussionmentioning

confidence: 47%

Microbialites at Gusev Crater, Mars.

Bianciardi

Rizzo²,

Farı́as³

et al. 2015

Astrobiol Outreach

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“…The ability of organisms to carry out their metabolic activities under the harsh conditions of high salt and low water is highly unusual (Rothschild, 1990). A few papers have reported the survival of archeal halophiles in dry salt over geological time scales (Norton et al, 1993;Grant et al, 1998;McGenity et al, 2000).…”

Section: Discussionmentioning

confidence: 99%

“…This newly discovered ecological microhabitat constitutes an extraordinary niche that allows life to exist in environments that are otherwise too dry for survival, such as that postulated for Mars (Rothschild, 1990). Indeed, the core of the Atacama Desert, in microbial terms, has been considered the most Mars-like environment of our planet (NavarroGonzález et al, 2003).…”

Section: Discussionmentioning

confidence: 99%

Endolithic Cyanobacteria in Halite Rocks from the Hyperarid Core of the Atacama Desert

Ascaso²,

2006

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In the driest parts of the Atacama Desert there are no visible life forms on soil or rock surfaces. The soil in this region contains only minute traces of bacteria distributed in patches, and conditions are too dry for cyanobacteria that live under translucent stones. Here we show that halite evaporite rocks from the driest part of the Atacama Desert are colonized by cyanobacteria. This colonization takes place just a few millimeters beneath the rock surface, occupying spaces among salt crystals. Our work reveals that these communities are composed of extremely resistant Chroococcidiopsis morphospecies of cyanobacteria and associated heterotrophic bacteria. This newly discovered endolithic environment is an extremely dry and, at the same time, saline microbial habitat. Photosynthetic microorganisms within dry evaporite rocks could be an important and previously unrecognized target for the search for life within our Solar System.

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“…Regardless of the processes (inorganic or biological) driving carbonate precipitation, where microorganisms are present, they are frequently entombed and fossilized. In addition to primary biofabric information, stromatolitic tufas frequently contain organic-walled microfossils and particulate kerogen (Figure 6b) Salt has been identified as a potentially important exploration target for past or present Martian life [Rothschild, 1990]. In addition to biological information, ancient evaporites may also yield valuable clues about past climate, as well as information about the composition of ancient fluids entrapped as inclusions in salt [Roedder, 1984;Knauth, 1993].…”

Section: Lacustrine Spring Carbonates (Tufas)mentioning

confidence: 99%

Exploring for a record of ancient Martian life

Farmer¹,

Marais²

1999

J. Geophys. Res.

299

222

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Abstract. The immediate task facing exopaleontology is to define a strategy to explore Mars for a fossil record during the decade-long exploration program that lies ahead. Consideration of the quality of paleontological information preserved under different geological conditions is important if we are to develop a strategy with broad applicability. The preservation of microbial fossils is strongly influenced by the physical, chemical, and biological factors of the environment which, acting together, determine the types of information that will be captured and retained in the rock record. In detrital sedimentary systems, preservation is favored by rapid burial in fine-grained, clay-rich sediments. In chemical sedimentary systems, preservation is enhanced by rapid entombment in finegrained chemical precipitates. For long-term preservation, host rocks must be composed of stable minerals that are resistant to chemical weathering and that form an impermeable matrix and closed chemical system to protect biosignatures from alteration during subsequent diagenesis or metamorphism. In this context, host rocks composed of highly ordered, chemically stable mineral phases, like silica (e.g., cherts) or phosphate (e.g., phosphorites), are especially favored. Such lithologies tend to have very long crustal residence times and, along with carbonates and shales, are the most common host rocks for the Precambrian microfossil record on Earth. Although we make the defensible assumption that Mars was more like the Earth early in its history, clearly, the geological and historical differences between the two planets are many. Such differences must be carefully considered when adapting an Earth-based strategy to Mars. IntroductionThe present emphasis in Mars exploration lies in the search for a fossil record [Klein and Farmer, 1995]. On Earth the long-term preservation of fossils occurs under a fairly narrow range of geological conditions [Knoll, 1984; Allison and Briggs, 1991a; Allison and Pye, 1994]. Favored environments share many basic physical and compositional characteristics that serve to guide the search for a microbial fossil record, whether in ancient stratigraphic sequences on Earth or, with appropriate adaptation, on other planetary surfaces like Mars. Because the basic conceptual framework and methodology required for paleontological exploration of other planetary bodies differ substantially from the search for extant life (embraced by the traditional discipline of exobiology), we refer to the former activity as "exopaleontology" [Farmer, 1995].In this paper we seek to create a historical perspective about the Earth's biosphere that will serve as a practical context for Mars exploration. The early history of the terrestrial biosphere and the factors that control life's limits are important constraints for assessing the probability that Mars developed life. Such constraints also provide a focus for the identification of potential habitable zones (past or present) on Mars.At the heart our strategy for Mars exopaleontology ...

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Earth analogs for Martian life. Microbes in evaporites, a new model system for life on Mars

Cited by 155 publications

References 74 publications

Microbialites at Gusev Crater, Mars.

Microbialites at Gusev Crater, Mars.

Endolithic Cyanobacteria in Halite Rocks from the Hyperarid Core of the Atacama Desert

Exploring for a record of ancient Martian life

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