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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

The origin of life

Research in the areas of precambrian paleontology, chemical evolution of genetically important monomers, prebiotic dehydration-condensation reactions, organic compounds in meteorites and interstellar space, and biological exploration of the planets is summarized. Fossils in precambrian cherts and findings of eukaryotic cells are described, and recent investigations of prebiotic conditions, energy sources, and starting materials for genetic molecules are outlined. Studies of homogeneous and heterogeneous dehydrations and of nonaqueous thermal dehydrations are described. The detection of amino acids, purines, and pyrimidines in meteorites and of biologically significant molecules in interstellar clouds is discussed, as well as the possibilities of life on Jupiter, Mars, and Titan.

Horowitz, N. H.↗
NASA NTRS1976

Exobiology and the origin of life

Abstracts on planetary studies and the search for extraterrestrial life are presented. Studies of the Jovian atmosphere were conducted. An assessment of the prospects for life on Mars is presented. And, the the means of contacting extraterrestrial civilizations is discussed.

Sagan, C.↗
NASA NTRS1978

Exobiology and the origin of life

Research supported wholly or in part by NASA is summarized, Topics covered include the molecular analysis of ultraviolet-photoproduced organic solids synthesized under simulated Jovian conditions; the molecular analysis of organic solids produced by electrical discharge in reducing atmospheres; the organic chemistry of interstellar grains; the spectra of possible organic solids present as aerosols in planetary atmospheres; far infrared studies of organic polymers of possible astrophysical interest; organic dust synthesized in reducing environments by ultraviolet radiation or electric discharge; the diffusion of galactic civilizations; eavesdropping on galactic civilizations; Lander imaging as a detector of life on Mars; and continuing puzzles about Mars. Bibliographic data is included for four additional publications not supported by NASA grant, but related to the objectives of the program.

Sagan, C.↗
NASA NTRS1979

A proposal concerning the origin of life on the planet earth

It is proposed that, contrary to the widely accepted Oparin thesis, life on earth arose not in the oceans but in the earth's atmosphere. Difficulties of the Oparin thesis relating to the nonbiological nature of prebiotic evolution are discussed, and autotrophic, photosynthetic cells are proposed as the first living organisms to emerge, thus avoiding these difficulties. Recent developments in the geology of the earth at the time of the emergence of life are interpreted as requiring the absence of liquid surface water, with water partitioned between a molten crust and a dense, CO2-rich atmosphere, similar to the present state of Venus. Biochemistry in such an atmosphere would be primarily membrane chemistry on the interfaces of atmospheric salt water droplets, proceeding at normal temperatures without the absorption of electrical discharges or UV light. Areas not sufficiently accounted for by this scenario include the development of genetic organization and the breaking of the runaway greenhouse condition assumed.

Woese, C. R.↗
NASA NTRS1981

Membrane lipids and the origin of life

The current state of knowledge regarding the development of biological systems is briefly reviewed. At a crucial stage concerning the evolution of such systems, the mechanisms leading to more complex structures must have evolved within the confines of a protected microenvironment, similar to those provided by the contemporary cell membranes. The major components found normally in biomembranes are phospholipids. The structure of the biomembrane is examined, and attention is given to questions concerning the availability of the structural components which are necessary in the formation of primitive lipid membranes. Two approaches regarding the study of protomembranes are discussed. The probability of obtaining ether lipids under prebiotic conditions is considered, taking into account the formation of cyclic and acyclic isoprenoids by the irradiation of isoprene with UV.

Oro, J.↗
NASA NTRS1983

Chemical evolution and the origin of life

A review is presented of recent advances made in the understanding of the formation of carbon compounds in the universe and the occurrence of processes of chemical evolution. Topics discussed include the principle of evolutionary continuity, evolution as a fundamental principle of the physical universe, the nuclear synthesis of biogenic elements, organic cosmochemistry and interstellar molecules, the solar nebula and the solar system in chemical evolution, the giant planets and Titan in chemical evolution, and comets and their interaction with the earth. Also examined are carbonaceous chondrites, environment of the primitive earth, energy sources available on the primitive earth, the synthesis of biochemical monomers and oligomers, the abiotic transcription of nucleotides, unified prebiotic and enzymatic mechanisms, phospholipids and membranes, and protobiological evolution.

Oro, J.↗
NASA NTRS1983

Investigation of compounds essential for the origin of life

Nucleic acid sequencing as a technique to determine the chemical and biological evolution of certain prokaryotic metabolic pathways is discussed. Protein in data and a microbiological organization of the prokaryotes is included.

Dayhoff, M. O.↗
NASA NTRS1985

Origin of life

The pathways of organic chemical synthesis, the chemical evolution on the early Earth leading to life was constrained by the development of the planet by accretion and core formation. The accretion and differentiation into the core-mantle-crust-atmosphere system strongly influenced the temperature and composition of the atmosphere, surface, and interior; but large gaps persist in our understanding of these processes. The time-span over which Earth acquired its volatiles, the composition of these volatiles, and the conditions under which outgassing of volatiles occurred to form the atmosphere, are unknown. Uncertainties in existing models for Earth accretion and early planetary development allows a wide range of possible prebiotic atmospheric compositions at the time and temperature when liquid water appeared and thermally-labile organic compounds could survive. These compositions range from strongly reducing atmospheres to mildly reducing ones.

Chang, S.↗