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At least 19 recordsLinked to original sources
PubMed1978

Current status of space medicine and exobiology.

An overview of the present state of aerospace medicine and planetary biology is given with emphasis on the ongoing search for extraterrestrial life and life science studies being made both by independent and cooperative investigations of the United States, the Soviet Union, the European Space Agency, and countries with an interest in gravitational physiology, radiation, planetary quarantine, exobiology, and general space biology. A suitable animal model for outer space medical research, in-orbit vestibular function investigations, biomedical problems in the Earth's normal 1-G gravitational intensity, and biological satellite experiments are discussed. The scope of exobiology, life detection programs, solar system organic chemistry, and attempted elucidation of the question of the origin and early evolution of life are also discussed. Evaluation of data acquired from a variety of sources indicates that all phases of exobiology lead to biopoesis and chemical evolution, with allied aviation, space, and environmental medicine being the major part of the search for extraterrestrial life.

Arrhythmias, Cardiac↗
PubMed1984

NASA's Exobiology Program.

The goal of NASA's Exobiology Program is to understand the origin, evolution, and distribution of life, and life-related molecules, on Earth and throughout the universe. Emphasis is focused on determining how the rate and direction of these processes were affected by the chemical and physical environment of the evolving planet, as well as by planetary, solar, and astrophysical phenomena. This is accomplished by a multi-disciplinary program of research conducted by over 60 principal investigators in both NASA and university laboratories. Major program thrusts are in the following research areas: biogenic elements; chemical evolution; origin of life; organic geochemistry; evolution of higher life forms; solar system exploration; and the search for extraterrestrial intelligence (SETI).

Biological Evolution↗
PubMed1984

Exobiology and the solar system: the Cassini mission to Titan.

The recent Voyager mission and the simulation experiments in the laboratory suggest that a complex nitrogen-organic chemistry is occuring at the periphery of Titan. Thus, this satellite of Saturn appears as a privileged place in the solar system for the study of extraterrestrial organic chemistry which can be considered as part of Exobiology. Projects of space mission relating to Titan are already under investigation, in particular with the "CASSINI" proposal. The CASSINI project is a combination of a Saturn orbiter and a Titan probe mission. Such a mission would allow the first study "in situ" of a complex extraterrestrial organic chemistry in atmospheric phase.

Animals↗
PubMed1999

Martian stable isotopes: volatile evolution, climate change and exobiological implications.

Measurements of the ratios of stable isotopes in the martian atmosphere and crust provide fundamental information about the evolution of the martian volatile and climate system. Current best estimates of the isotope ratios indicate that there has been substantial loss of gases to space and exchange of gases between the atmosphere and the crust throughout geologic time; exchange may have occurred through circulation of water in hydrothermal systems. Processes of volatile evolution and exchange will fractionate the isotopes in a manner that complicates the possible interpretation of isotopic data in terms of any fractionation that may have been caused by martian biota, and must be understood first. Key measurements are suggested that will enhance our understanding of the non-biological fractionation of the isotopes and of the evolution of the martian volatile system.

Climate↗
PubMed1984

The Antarctic cryptoendolithic ecosystem: relevance to exobiology.

Cryptoendolithic microorganisms in the Antarctic desert live inside porous sandstone rocks, protected by a thin rock crust. While the rock surface is abiotic, the microclimate inside the rock is comparatively mild. These organisms may have descended from early, pre-glaciation Antarctic life forms and thus may represent the last outpost of life in a gradually deteriorating environment. Assuming that life once arose on Mars, it is conceivable that, following the loss of water, the last of surviving organisms withdrew to similar insulated microenvironments. Because such microscopic pockets have little connection with the outside environment, their detection may be difficult. The chances that the Viking lander could sample cryptoendolithic microorganisms in the Antarctic desert would be infinitesimal.

Arctic Regions↗
PubMed1983

[Mathematical models of various exobiological situations].

To analyze quarantine and sterilization requirements of space flights, the possibility of coexistence of terrestrial and aboriginal forms of life was theoretically explored. It was found that if the trophic chain with the terrestrial form acting as a consumer evolves both forms may coexist. Their quantitative relations can be explained by a good number of hypotheses. The study of spatial distribution and diffusion suggests wave-like processes similar to the distribution of autocatalytic reactions in chemical kinetics.

Aerospace Medicine↗
PubMed1998

Biogenic catalysis of soil formation on Mars?

The high iron abundance and the weak ferric iron spectral features of martian surface material are consistent with nanophase (nm-sized) iron oxide minerals as a major source of iron in the bright region soil on Mars. Nanophase iron oxide minerals, such as ferrihydrite and schwertmannite, and nanophase forms of hematite and goethite are formed by both biotic and abiotic processes on Earth. The presence of these minerals on Mars does not indicate biological activity on Mars, but it does raise the possibility. This work includes speculation regarding the possibility of biogenic soils on Mars based on previous observations and analyses. A remote sensing goal of upcoming missions should be to determine if nanophase iron oxide minerals, clay silicates and carbonates are present in the martian surface material. These minerals are important indicators for exobiology and their presence on Mars would invoke a need for further investigation and sample return from these sites.

Catalysis↗
PubMed1997

Chemical evolution on Titan: comparisons to the prebiotic earth.

Models for the origin of Titan's atmosphere, the processing of the atmosphere and surface and its exobiological role are reviewed. Titan has gained widespread acceptance in the origin of life field as a model for the types of evolutionary processes that could have occurred on prebiotic Earth. Both Titan and Earth possess significant atmospheres (> or = 1 atm) composed mainly of molecular nitrogen with smaller amounts of more reactive species. Both of these atmospheres are processed primarily by solar ultraviolet light with high energy particles interactions contributing to a lesser extent. The products of these reactions condense or are dissolved in other atmospheric species (aerosols/clouds) and fall to the surface. There these products may have been further processed on Titan and the primitive Earth by impacting comets and meteorites. While the low temperatures on Titan (approximately 72-180 K) preclude the presence of permanent liquid water on the surface, it has been suggested that tectonic activity or impacts by meteors and comets could produce liquid water pools on the surface for thousands of years. Hydrolysis and oligomerization reactions in these pools might form chemicals of prebiological significance. Other direct comparisons between the conditions on present day Titan and those proposed for prebiotic Earth are also presented.

Atmosphere↗
PubMed1975

Life and chirality beyond the earth.

An attempt is made to show that the phenomenon of chirality- of which optical activity is but one consequence- is by no means restricted to life on Earth, but is common throughout the universe. Several independent sources have been investigated including: statistical fluctuations; stereoselective physical factors; and energetic differences between enantiomeric molecules. It is emphasised that a search for chirality as an indicator for life elsewhere in space provides an excellent tool for the fascinating question of exobiology. Still one must be aware of the limitations of the experimental methods and their interpretations.

Extraterrestrial Environment↗