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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Organic synthesis in a simulated Jovian atmosphere. III - Synthesis of aminonitriles

The products from spark and semicorona discharges through mixtures simulating the Jovian atmosphere were analyzed by gas chromatography combined with mass spectrometry. When the reaction was performed at -80 C, 3-ethylaminopropionitrile and a number of higher homologs were formed. On the other hand, at +20 C, higher molecular-weight material appeared which yielded aminonitrile-derived fragments on mass spectrometry. Although the spectra were not identical, there were notable similarities between these and the mass spectra of some compounds present in the Murray and Orgeuil meteorites. Aminonitriles may occur as minor constituents of the Jovian atmosphere and perhaps by cyclization may produce pyrimidines.

Molton, P. M.↗
NASA NTRS1980

Plasma chemistry and organic synthesis

The characteristic features of chemical reactions using low temperature plasmas are described and differentiated from those seen in other reaction systems. A number of examples of applications of plasma chemistry to synthetic reactions are mentioned. The production of amino acids by discharge reactions in hydrocarbon-ammonia-water systems is discussed, and its implications for the origins of life are mentioned.

Tezuka, M.↗
NASA NTRS2012

Will Organic Synthesis Within Icy Grains or on Dust Surfaces in the Primitive Solar Nebula Completely Erase the Effects of Photochemical Self Shielding?

There are at least 3 separate photochemical self-shielding models with different degrees of commonality. All of these models rely on the selective absorption of (12))C(16)O dissociative photons as the radiation source penetrates through the gas allowing the production of reactive O-17 and O-18 atoms within a specific volume. Each model also assumes that the undissociated C(16)O is stable and does not participate in the chemistry of nebular dust grains. In what follows we will argue that this last, very important assumption is simply not true despite the very high energy of the CO molecular bond.

Nuth, Joseph A., III↗
NASA NTRS1986

Isotopic characterisation of prebiotic synthesis of organic material

Many primitive meteorites contain an insoluble organic material, much like terrestrial kerogen, whose mode of origin is currently unknown. When sujbected to stepwise decomposition, this material, unlike its terrestrial counterpart, reveals characteristic release patterns for the stable isotopes of carbon, hydrogen and nitrogen as a function of fractional release of each element. The purpose of this study is to try to match those release patterns using organic matter synthesised in the laboratory under controlled conditions. If successful, such a study would shed light on the origin of kerogen-like organic matter in the early solar system and, by extension, on prebiotic organic synthesis in general. The range of possible syntheses, starting materials and reaction conditions to be investigated is considerable. Samples analysed to date include: a heavy oil produced by Fischer-Tropsch-type catalysis of CO + H2; a solid residue generated by a plasma discharge in CO + H2 + N2; a solid deposited on the electrodes of a Miller-Urey synthesis operating on CH4 + H2O + N2; and a solid residue formed by polymerization of light hydrocarbons procured by a Miller-Urey discharge acting on CH4. Significant structure is observed in the release patterns for the carbon and hydrogen isotopes from the synthetic samples, though there is little evidence for isotopic fractionation during the analysis itself.

Kerridge, J. F.↗
NASA NTRS1983

The atmosphere of the primitive earth and the prebiotic synthesis of organic compounds

The prebiotic synthesis of organic compounds is investigated using a spark discharge on various simulated prebiotic atmospheres at 25 C. It is found that glycine is almost the only amino acid produced from the model atmospheres containing CO and CO2. These results show that the maximum yield is about the same for the three carbon sources (CO, CO2, and CH4) at high H2/carbon ratios, but that CH4 is superior at low H2/carbon ratios. CH4 is found to yield a much greater variety of amino acids than either CO or CO2. If it is assumed that amino acids more complex than glycine were required for the origin of life, then these findings indicate the need for CH4 in the primitive atmosphere. The yields of cyanide and formaldehyde are shown to parallel the amino acid results, with yields of HCN and H2CO as high as 13 percent based on carbon. Ammonia is also found to be produced from N2 in experiments with no added NH3 in yields as high as 4.9 percent. These results indicate that large amounts of NH3 would have been synthesized on the primitive earth by electric discharges.

Miller, S. L.↗
NASA NTRS1980

Cosmic ray synthesis of organic molecules in Titan's atmosphere

The possible synthesis of organic molecules by the absorption of galactic cosmic rays in an N2-CH4-H2 Titan model atmosphere has been studied. The cosmic-ray-induced ionization results in peak electron densities of 2000/cu cm, with NH(+), C3H9(+), and C4H9(+) being among the important positive ions. Details of the ion and neutral chemistry relevant to the production of organic molecules are discussed. The potential importance of N(2D) reactions with CH4 and H2 is also demonstrated. Although the integrated production rate of organic matter due to the absorption of the cosmic ray cascade is much less than that by solar ultraviolet radiation, the production of nitrogen-bearing organic molecules by cosmic rays may be greater.

Capone, L. A.↗
NASA NTRS1979

Comets: Cosmic connections with carbonaceous meteorites, interstellar molecules and the origin of life

The ions, radicals, and molecules observed in comets may be derived intact or by partial decomposition from parent compounds of the sort found either in the interstellar medium or in carbonaceous meteorites. The early loss of highly reducing primitive atmosphere and its replacement by a secondary atmosphere dominated by H2O, CO2, and N2, as depicted in current models of the earth's evolution, pose a dilemma for the origin of life: the synthesis of organic compounds necessary for life from components of the secondary atmosphere appears to be difficult, and plausible mechanisms have not been evaluated. Both comets and carbonaceous meteorites are implicated as sources for the earth's atmophilic and organogenic elements. A mass balance argument involving the estimated ratios of hydrogen to carbon in carbonaceous meteorites, comets, and the crust and upper mantle suggests that comets supplied the earth with a large fraction of its volatiles. The probability that comets contributed significantly to the earth's volatile inventory suggests a chemical evolutionary link between comets, prebiotic organic synthesis, and the origin of life.

Chang, S.↗
NASA NTRSDate not supplied

Formation of Complex Organic Molecules (COMs) from Polycyclic Aromatic Hydrocarbons (PAHs): Top-Down Synthesis of organics in planetary systems

Complex, organic molecules have been found in many solar system objects (i.e., dust, comets, meteorites, moons, etc.); however, their origins and formation remain a mystery. Two chemical evolutionary pathways have been proposed to explain the organic inventory of our solar system. The first pathway, the top-down approach, suggests an interstellar (ISM) heritage whereby the organic material found in the solar system formed from the erosion and functionalization of large pre-solar carbon-bearing species (mainly large Polycyclic Aromatic Hydrocarbons or PAHs). The second pathway suggests that the origin of the Solar System prebiotic matter is the result of bottom-up synthesis from small reactive molecules (e.g., formaldehyde – H2CO, acetylene – H2C2, and similar species). In this second scenario, it is supposed that very few, if any, pre-solar large molecules could have survived due to the proto - solar nebula radiation environment. Polycyclic Aromatic Hydrocarbons or PAHs comprise ~20-30% of all available carbon in the Universe. The PAHs found within our Solar System tend to be smaller than those suspected to be in the ISM, comprised of only 14 to 18 carbon atoms in size whereas ISM PAHs are typically 50 to 100 carbon atoms. The disparity in PAH sizes between the ISM and Solar System environments is not understood, but may point to conversion of large ISM PAHs to Solar System Organics. This presentation details recent experiments regarding the stability of large PAHs to the various types of radiation found within a proto - solar disk and the production of smaller, complex, molecules from the degradation of the larger PAHs. The presentation will highlight differences and similarities in degradation products based on experimental conditions (e.g., radiation type) and discuss future work with a new experimental setup known as ICEE (Institute for Carbon Evolution Experiments).

molecukes↗
NASA NTRS1985

The composition of the primitive atmosphere and the synthesis of organic compounds on the early Earth

The generally accepted theory for the origin of life on the Earth requires that a large variety of organic compounds be present to form the first living organisms and to provide the energy sources for primitive life either directly or through various fermentation reactions. This can provide a strong constraint on discussions of the formation of the Earth and on the composition of the primitive atmosphere. In order for substantial amounts of organic compounds to have been present on the prebiological Earth, certain conditions must have existed. There is a large body of literature on the prebiotic synthesis of organic compounds in various postulated atmospheres. In this mixture of abiotically synthesized organic compounds, the amino acids are of special interest since they are utilized by modern organisms to synthesize structural materials and a large array of catalytic peptides.

Bada, J. L.↗
NASA NTRS2024

Experimental Studies on the Effect of Impact Processes on the Formation and Evolution of Amino Acids

Introduction: A critical step in the emergence of life on Earth was the synthesis of larger organic molecules from simple building blocks such as NH3, CO2, H2O, and CH3OH. The presence of amino acids and other complex organics in comets and meteorites demonstrates that widespread organic synthesis likely occurred across the early solar system. Building on previous work [e.g., 1-3], we systematically explore impact-driven chemical evolution of exogenous organics and their precursors. Collisional processes may also have provided a source of energy for the formation of more complex organics from endogenous building blocks. The high flux of impactors to Earth immediately prior to and during the origins of life suggests that impacts could have played a critical role. Key Questions: 1. How are the formation and evolution of amino acids affected by the presence of a mineral matrix during cometary and asteroidal impacts onto the early Earth? 2. Do some minerals (e.g., phyllosilicates) provide a more robust protective framework or reactive surface site for amino-acid formation and/or polymerization? 3. Does the abundance of ices and/or amino acids relative to that of the mineral matrix affect the formation and evolution of amino acids? 4. Are there impact velocities/shock pressures at which formation or polymerization of amino acids is favored or precluded? Experimental Approach: This study systematically examines the conditions under which amino acids and other organic molecules can form, be polymerized, and/or be destroyed during impact events into particulate regolith simulants. Variable parameters include the modal composition of this regolith (silicate matrices, ratios of ices, silicates, and amino acids) and impact velocities/shock pressures. Impacts experiments were performed using the two-stage light-gas gun (LGG), vertical gun (VG), and flat-plate accelerator (FPA) in the Experimental Impact Lab at JSC. FPA experiments were performed over a range of shock pressures (11.3-31.5 GPa) using CM chondrite simulant mixed with amino acids at ratios of 0:10, 1:10, 1:103, and 1:106 (amino acid:host). Techniques for mixing cometary ices have been optimized and test runs have been performed using the LGG (see figure below). Analysis: Post-impact, samples are heated in water to extract amino acids and peptides. Extracts are characterized via liquid chromatography-mass spectrometry (LC-MS) and the mineralogies of solid residues are characterized using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Additional LC-MS and mineralogical analyses are underway.

Eve L Berger↗
NASA NTRS1984

Solar wind and cosmic ray irradiation of grains and ices - application to erosion and synthesis of organic compounds in the solar system

Solar wind and cosmic and cosmic ray irradiation of grains induces physical and chemical effects including their erosion and the synthesis of molecular compounds within the implanted layers. The experiments performed with H2O ice implanted by keV ions are presented. The ion implantation is intended to simulate the irradiation of comets, ring grains, and satellites of outer planets, either by the primitive solar particles or by contemporary solar wind (SW) or solar cosmic rays (SCR) fluxes. The detection of molecules was obtained through in-situ infrared spectroscopy. A model is proposed for the formation of organic matter within icy solar system bodies which is in agreement with experimental results of erosion rates. The organic molecules, frozen-in within the icy mantles of the grains present in the protosolar nebula, would originate from their primitive irradiation. Such an irradiation would have taken place during an early stage of the proto-sun, when both the SW and SCR particles were more intense by orders of magnitude.

Rocard, F.↗
NASA NTRS2002

Prebiotic Processing induced by Comet and Meteor Impact

In their study of organic synthesis from impact shocks using the laser-induced-plasma (LIP) technique, McKay and Borucki(l) found that organic synthesis preferentially occurred in a reducing gas mixture rich in methane, and not in a mixture rich in carbon dioxide. This result means chemical models based on the thermodynamical equilibrium approach do not apply to shock chemistry. In this study, we employ the technique of reacting flow, i.e., chemical kinetics in a fluid flow, to simulate the chemistry occurring in LIP and in the wake region from comet or meteor impact. Three different air compositions have been used: (1) 1/3 CO2 and 2/3 H2, (2) pure CH4, and (3) 1/4 CH4, 1/4 CO2, and 1/2 H2O. The stoichiometric ratio of gas mixtures (1) and (3) are kept the same. For (1) we obtain equal mole fractions of CO and H2O as the major products and for (2) C2H2 is the major product. In both cases our results are in agreement with Ref. (1). For (3) we find an interesting case where the nature of chemicals produced to be critically dependent on the flowfield temperature. At the higher temperature part of the wake region, CO and H2O are the dominant products, whereas in the cooler region C2H2 is the dominant product. Further studies of these reactions, as well as for the gas mixture including N2, are being pursued.

Dateo, Christopher E.↗
NASA NTRS1996

Hydrothermal systems as environments for the emergence of life

Analysis of the chemical disequilibrium provided by the mixing of hydrothermal fluids and seawater in present-day systems indicates that organic synthesis from CO2 or carbonic acid is thermodynamically favoured in the conditions in which hyperthermophilic microorganisms are known to live. These organisms lower the Gibbs free energy of the chemical mixture by synthesizing many of the components of their cells. Primary productivity is enormous in hydrothermal systems because it depends only on catalysis of thermodynamically favourable, exergonic reactions. It follows that hydrothermal systems may be the most favourable environments for life on Earth. This fact makes hydrothermal systems logical candidates for the location of the emergence of life, a speculation that is supported by genetic evidence that modern hyperthermophilic organisms are closer to a common ancestor than any other forms of life. The presence of hydrothermal systems on the early Earth would correspond to the presence of liquid water. Evidence that hydrothermal systems existed early in the history of Mars raises the possibility that life may have emerged on Mars as well. Redox reactions between water and rock establish the potential for organic synthesis in and around hydrothermal systems. Therefore, the single most important parameter for modelling the geochemical emergence of life on the early Earth or Mars is the composition of the rock which hosts the hydrothermal system.

Non-NASA Center↗
NASA NTRS1991

A note on the prebiotic synthesis of organic acids in carbonaceous meteorites

Strong similarities between monocarboxylic and hydrocarboxylic acids in the Murchison meteorite suggest corresponding similarities in their origins. However, various lines of evidence apparently implicate quite different precursor compounds in the synthesis of the different acids. These seeming inconsistencies can be resolved by postulating that the apparent precursors also share a related origin. Pervasive D enrichment indicates that this origin was in a presolar molecular cloud. The organic acids themselves were probably synthesized in an aqueous environment on an asteroidal parent body, the hydroxy (and amino) acids by means of the Strecker cyanohydrin reaction.

Kerridge, John F.↗