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  • 1
    Electronic Resource
    Electronic Resource
    Perennially ice-covered Lake Hoare, Antarctica: physical environment, biology and sedimentation (1989)
    Springer
    Hydrobiologia 172 (1989), S. 305-320 
    Details
    ISSN: 1573-5117
    Keywords: Antarctica ; climatic changes ; gas solubility ; ice-covered lakes ; Lake Hoare
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lake Hoare (77° 38′ S, 162° 53′ E) is a perennially ice-covered lake at the eastern end of Taylor Valley in southern Victoria Land, Antarctica. The environment of this lake is controlled by the relatively thick ice cover (3–5 m) which eliminates wind generated currents, restricts gas exchange and sediment deposition, and reduces light penetration. The ice cover is in turn largely controlled by the extreme seasonality of Antarctica and local climate. Lake Hoare and other dry valley lakes may be sensitive indicators of short term (〈 100 yr) climatic and/or anthropogenic changes in the dry valleys since the onset of intensive exploration over 30 years ago. The time constants for turnover of the water column and lake ice are 50 and 10 years, respectively. The turnover time for atmospheric gases in the lake is 30–60 years. Therefore, the lake environment responds to changes on a 10–100 year timescale. Because the ice cover has a controlling influence on the lake (e.g. light penetration, gas content of water, and sediment deposition), it is probable that small changes in ice ablation, sediment loading on the ice cover, or glacial meltwater (or groundwater) inflow will affect ice cover dynamics and will have a major impact on the lake environment and biota.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00031629
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  • 2
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    The chemical reactivity of the Martian soil and implications for future missions (1994)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Possible interpretations of the results of the Viking Biology Experiments suggest that greater than 1 ppm of a thermally labile oxidant, perhaps H2O2, and about 10 ppm of a thermally stable oxidant are present in the martian soil. We reexamine these results and discuss implications for future missions, the search for organics on Mars, and the possible health and engineering effects for human exploration. We conclude that further characterization of the reactivity of the martian regolith materials is warrented-although if our present understanding is correct the oxidant does not pose a hazard to humans. There are difficulties in explaining the reactivity of the Martian soil by oxidants. Most bulk phase compounds that are capable of oxidizing H2O to O2 per the Gas Exchange Experiment (GEx) are thermally labile or unstable against reduction by atmospheric CO2. Models invoking trapped O2 or peroxynitrates (NOO2(-)) require an unlikely geologic history for the Viking Lander 2 site. Most suggested oxidants, including H2O2, are expected to decompose rapidly under martian UV. Nonetheless, we conclude that the best model for the martian soil contains oxidants produced by heterogeneous chemical reactions with a photochemically produced atmospheric oxidant. The GEx results may be due to catalytic decomposition of an unstable oxidizing material by H2O. We show that interfacial reaction sites covering less than 1% of the available soil surfaces could explain the Viking Biology Experiments results.
    Keywords: SPACE BIOLOGY
    Type: ICARUS (ISSN 0019-1035); 108; 1; p. 146-157
    Format: text
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  • 3
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    Relevance of antarctic microbial ecosystems to exobiology (1993)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Antarctic microbial ecosystems which provide biological and physical analogs that can be used in exobiology are studied. Since the access to extraterrestrial habitats is extremely difficult, terrestrial analogs represent the best opportunity for both formulation and preliminary testing of hypothesis about life. Antarctica, as one of few suitable environments on earth is considered to be a major locus of progress in exobiology.
    Keywords: SPACE BIOLOGY
    Type: ; : Conference on the
    Format: text
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  • 4
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    The implantation of life on Mars - Feasibility and motivation (1992)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Scientific concepts are reviewed regarding the potential formation and development of a life-bearing environment on Mars, and a potential ecopoiesis scenario is given. The development of the earth's biosphere is defined, and the major assumptions related to the formation of Martian life are listed. Three basic phases are described for the life-implantation concept which include determining whether sufficient quantities of volatiles are available, engineering the warming of the planet, and implanting microbial communities if necessary. Warming the planet theoretically releases liquid H2O and produces a thick CO2 atmosphere, and the implantation of biological communities is only necessary if no indigenous microbes emerge. It is concluded that a feasibility study is required to assess the possibilities of implanting life on Mars more concretely.
    Keywords: SPACE BIOLOGY
    Type: Advances in Space Research (ISSN 0273-1177); 12; 4, 19
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  • 5
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    Exobiology and future Mars missions - The search for Mars' earliest biosphere (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The primordial Mars may have possessed a thick carbon dioxide atmosphere, with liquid water common on the surface, similar in many ways to the primordial earth. During this epoch, billions of years ago, the surface of Mars could have been conducive to the origin of life. It is possible that life evolved on Mars to be later eliminated as the atmospheric pressure dropped. Analysis of the surface of Mars for the traces of this early Martian biota could provide many insights into the phenomenon of life and its coupling to planetary evolution.
    Keywords: SPACE BIOLOGY
    Type: Advances in Space Research (ISSN 0273-1177); 6; 12, 1; 269-285
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  • 6
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    The early environment and its evolution on Mars - Implications for life (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: There is considerable evidence that the early climate of Mars was very different from the inhospitable conditions there today. This early climate was characterized by liquid water on the surface and a dense atmosphere composed predominantly of CO2. The duration of these warm initial conditions on the surface of Mars is uncertain, but theoretical models suggest that they could have persisted for hundreds of millions up to a billion years. From studies of the earth's earliest biosphere, it is known that, by 3.5 Gyr ago, life had originated on earth and reached a fair degree of biological sophistication. If Mars did maintain a clement environment for longer than it took for life to originate on earth, then the question of the origin of life on Mars follows naturally. Since over two thirds of the Martian surface is more than 3.5 Gyr old, the possibility exists that Mars may hold the best record of the events that led to the origin of life, even though there may be no life there today.
    Keywords: SPACE BIOLOGY
    Type: Reviews of Geophysics (ISSN 8755-1209); 27; 189-214
    Format: text
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  • 7
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    Urey Prize Lecture - Planetary evolution and the origin of life (1991)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: One of the principal questions concerning planetary evolution and life's origins relates to the early-earth organic material's origination in situ, outer solar system importation, or simple irrelevance to the emergence of organisms. Additional considerations encompass the character of interstellar organic material and its relationship to outer solar system organic compounds, and the possibility of life's emergence in the early Mars. Attention is given to the essentiality of liquid water for life-forms, in the role not only of a reaction medium among molecules but that of a basis for hydrophylic and hydrophobic groups' bonding.
    Keywords: SPACE BIOLOGY
    Type: Icarus (ISSN 0019-1035); 91; 93-100
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  • 8
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    History of water on Mars - A biological perspective (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: A general scenario is developed for the history of liquid water on the surface of Mars, according to which the history of water on Mars can be divided into four epochs based on the fundamental temperature and pressure characteristics. In Epoch I, the mean annual temperature is assumed to have been above freezing and the pressure to have been above 1 atm; liquid water was widespread and life could have arisen and become abundant. In Epoch II, the mean annual temperature fell below freezing, but peak temperatures were above freezing; In Epoch II ice-covered lakes could have provided a habitat for life. In Epoch III, both the mean and the peak temperatures were below freezing, and only transient liquid water would be possible; under these conditions, microbial ecosystems living in endolithic rock 'greenhouses' could have continued to survive. Finally, in Epoch IV, the pressure dropped to near the triple point pressure of water; at this stage, life on the surface of Mars would have become extinct.
    Keywords: SPACE BIOLOGY
    Type: Advances in Space Research (ISSN 0273-1177); 12; 4, 19
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  • 9
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    Mars Rover Sample Return: A sample collection and analysis strategy for exobiology (1989)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: For reasons defined elsewhere it is reasonable to search for biological signatures, both chemical and morphological, of extinct life on Mars. Life on Earth requries the presence of liquid water, therefore, it is important to explore sites on Mars where standing bodies of water may have once existed. Outcrops of layered deposits within the Valles Marineris appear to be ancient lake beds. Because the outcrops are well exposed, relatively shallow core samples would be very informative. The most important biological signature to detect would be organics, microfossils, or larger stromato-like structures, although the presence of cherts, carbonates, clays, and shales would be significant. In spite of the limitations of current robotics and pattern recognition, and the limitations of rover power, computation, Earth communication bandwidth, and time delays, a partial scenario was developed to implement such a scientific investigation. The rover instrumentation and the procedures and decisions and IR spectrometer are described in detail. Preliminary results from a collaborative effort are described, which indicate the rover will be able to autonomously detect stratification, and hence will ease the interpretation burden and lead to greater scientific productivity during the rover's lifetime.
    Keywords: SPACE BIOLOGY
    Type: Exobiology and Future Mars Missions; p 55
    Format: application/pdf
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  • 10
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    Planetary protection issues in advance of human exploration of Mars (1989)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The major planetary quarantine issues associated with human exploration of Mars, which is viewed as being more likely to harbor indigenous life than is the moon, are discussed. Special attention is given to the environmental impact of human missions to Mars due to contamination and mechanical disturbances of the local environment, the contamination issues associated with the return of humans, and the planetary quarantine strategy for a human base. It is emphasized that, in addition to the question of indigenous life, there may be some concern of returning to earth the earth microorganisms that have spent some time in the Martian environment. It is suggested that, due to the fact that a robot system can be subjected to more stringent controls and protective treatments than a mission involving humans, a robotic sample return mission can help to eliminate many planetary-quarantine concerns about returning samples.
    Keywords: SPACE BIOLOGY
    Type: Planetary Biology and Origins of Life, 20th, 21st, and 23rd, Espoo, Finland, July 18-29, 1988) Advances in Space Research (ISSN 0273-1177); 197-202
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