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Review article on polycyclic aromatic hydrocarbons in interplanetary dust and in meteorites; they have similar Raman spectra, isotope ratios, etc.
Report an emission feature of Comet Wilson, the spectrum of which indicates that it is probably a release of organic grains. However, the band shape does not resemble biological materials thus far studied.
Using fluorescent microscopy on Orgueil carbonaceous chondrite, conclude that most organic matter is small micron-wide spheres.
Criticizes Nagy et al.'s comparison of mass spectra of biogenic materials (butter and recent sediments) to Orgueil, noting that the two biogenic substances look very dissimilar. Points out that Orgueil sample is likely to have absorbed fossil fuel residues in the century of its stay in New York City. Finds that resemblance between cracking pattern of Orgueil distillate and that of known biogenic hydrocarbons interesting but inconclusive. Questions Nagy's use of statistics as well.
Unsuccessful attempt to confirm Nagy et al.'s finding of organized elements in the Orgueil stone. Found fewer simple-morphology particles than claimed by Nagy and no evidence of biological origin. Found no rare complex-morphology particles and suspects that those reported by Nagy et al. were contaminants or artifacts.
Reports that a sample of the Orgueil stone in the Musée d' Histoire Naturelle, Montauban, France, contains coal fragments, reed seed-capsules, and a glue-like collagen. Concludes this sample was either deliberately or accidentally contaminated in the XIX Century. (The reed is local to the Montauban area, so is unlikely to be extraterrestrial). Perhaps other samples were contaminated as well.
Review article on organic compounds in meteorites, believed to have formed by catalytic reactions of CO, hydrogen and ammonia in the solar nebula.
Because organic matter is largely destroyed by heating in a major impact, it is important to calculate how much organic material arrives in small meteorites which are gently decelerated. Figures for present and earlier epochs are deduced.
Review article on interstellar grains (diamond, silicon carbide, graphite) in meteorites.
States that Hahn's ``crinoids'' are pseudofossils similar to inorganic structure created in the laboratory by S. Meunier.
Try to calculate (from the Langevin equation) adsorption of various light molecules into silica grains. Conclude that abundance of interstellar grains likely to be small.
Argues for direct propagation of life between planets by microbes hurled into near-planet space by storms, then propelled by radiation pressure. (No comets or meteorites required.)
Report discovery of disks of grains near three main sequence stars, roughly where the ``Kuiper belt'' of comets would lie in our solar system.
Attack Engel and Nagy, 1982, pointing out that a more likely explanation for the fact that only the protein amino acids are non-racemic is that they are terrestrial contaminants.
Engel and Nagy reply that they had made no speculations, just reported their results, and defend their analytic technique.
Suggest that alpha-amino isobutyric acid is associated with the KT boundary. If so, might earlier impacts have introduced the amino acids necessary for the appearance of life?
Review article on amino acids in meteorites. Argues that the racemic nature of meteoritic acids suggest that amino acid chirality only arose after life was well-established on Earth.
Review of information on organic materials in the Orgueil carbonaceous chondrite.
Report on analysis of polymer-like organic extract from Orgueil. Conclude it is a complex mixture similar, but not identical, to kerogen.
Attack the idea of Hoyle and Wickramasinghe that life arose in comets. Most organics are sublimed or blown off at perihelion in too short a time to migrate into interior; the structure is too tenuous for a liquid core; if there were a liquid core (due to aluminium-26), it would be too radioactive for life.
Extract a non-graphitic carbonaceous phase from the Allende carbonaceous chondrite. It is probably not a classical polymer because it is ``intractable'' and thermally stable.
Report discovery of polycyclic aromatic hydrocarbons and fullerenes in the Allende carbonaceous chondrite by time-of-flight mass spectroscopy.
Report existence of fluorescent organic microspheres indigenous to Orgueil carbonaceous chondrite.
A theoretical paper seeking to explain presence of petroleumlike hydrocarbons in meteorites in terms of a reaction between metal carbides and water.
Found humic acid in Alais carbonaceous chondrite; decided a biological origin unlikely.
Reports alleged discovery of fossil multi-cellular invertebrates in stones of 1866 Knyahinya fall by Hahn and Weinland.
German-language discussion, according to the abstract, of possible significance of carbonaceous chondrite biomolecules to exobiology.
Comment on the existence of numerous terrestrial pseudo-microfossils which might fool biologists.
Report discovery of interstellar SiC grain in the Murray carbonaceous chondrite.
Attempt analysis of polymerlike materials extracted from Orgueil carbonaceous chondrite, coal, and kerogen by ozonolysis, but while there are marked similarities, the problem is complicated.
Reports discovery of complex organic compounds in the Mokoia carbonaceous chondrite. Speculates they are either from decay of a dead extraterrestrial life-form or are abiotic compounds formed in the early solar system.
Find complex organic microstructures, some resembling unicellular organisms, in the Mokoia carbonaceous chondrite. Take no position on their origin.
Argues that the large quantity of organic material associated with meteorites, especially with carbonaceous chondrites, is sufficient for a non-biological explanation of petroleum---also argues that some microfossils found in terrestrial sediments may be in fact ``polymeric hydrocarbons derived from meteoritic fragments,'' (i.e., that some terrestrial microfossils are really Nagy-type objects of non-biological, extraterrestrial origin).
Isotopic analysis shows that organic material in various carbonaceous chondrites probably extraterrestrial, not a contaminant.
Reports discovery of urea, acetamide, and various aromatic acids in carbonaceous chondrites.
Review article about organic substances in carbonaceous chondrites; agnostic about ``organized structures.''
Review paper on carbonaceous chondrites and early preCambrian rocks.
Over 8,000 references.
Very brief review of current status of exobilogogy; the entire joural issue develops these themes.
Attacks Lipman's claimed discovery of organic nitrogen compounds.
An outstanding history of the study of meteorites (and of the role of meteorites in prescientific culture), including the debate over their exobiological significance.
Attack Studier et al.'s 1965 work with carbonaceous chondrites on various grounds as inadequate to serve as basis for any theory of carbonaceous chondrite origins.
Argue that numerous other more "plausable" models explain the Comet Halley dust spectrum as well as does the theory of Hoyle and Wickramasinghe. Also criticize this theory's choice of a temperature.
Describe laboratory spectra of simulated comet ice containing irradiated organic residues and producing a spectrum similar to that of Halley's comet.
Argue against Hoyle and Wickramasinghe that if freeze-dried bacteria fit spectrum of Comet Halley, it is because of the presence of common organic functional groups found in bacteria and in non-living systems. Concede, however, that they had overstated their case. Also defend themselves against criticism by Greenberg and Zhao.
News article about discovery of asymetry in extraterrestrial amino acids, and Zahnle-Grinspoon proposal for method by which amino acids were transfered to earth by evaporating comet.
Suggests a ``soft landing'' mechanism by which comet could land on planet relatively intact and melt, providing a growth habitat for any life or prebiotic material. The probability of a soft landing is admitted to be low, about one per million.
Describes discovery of organized structures in New York and DC samples of Orgueil stone, and in the Ivuna stone, both carbonaceous chondrites, but not in ordinary stony meteorites, Holbrook and Bruderheim.
Morphology and staining behavior of organic structures in carbonaceous chondrites suggest that they are biological. The morphological method, standard in palynology, is defended.
Verifies the abundance of organized structures in Orgueil.
Examined the Orgueil carbonaceous chondrite and found material comparable to peat and lignite.
Polycyclic aromatic hydrocarbons reported in Cold Bokkeveld and Orgueil carbonaceous chondrites. Remarks that there are several possible origins (extraterrestrial; atmospheric pyrolysis; burning of material at impact site; contamination).
Describe numerous amides extracted from Murchison carbonaceous chondrite. Suggest these might serve as basis of primitive sequence coding system.
Reports that twice as much amino acid can be extracted from the Murchison carbonaceous chondrite by subjecting samples to acid hydrolysis. This could mean either that more amino acids exist in rock than previously thought or that precursors exist which form amino acids in extraction process.
Amino acids reported in extracts from Nogoya and Mokoia carbonaceous chondrites. The Nogoya extract differs from previously studied samples.
Report on amino acids extracted from Murchison carbonaceous chondrite. Their properties are found to differ from those of acids created in electric disharge and Fischer-Tropsch experiments.
55 amino acids have been found in Murchison carbonaceous chondrite; 36 unique to meteorites.
Obtain carbon-13 NMR spectra of insoluble organic residues from Orgueil, Murchison, and Allende carbonaceous chondrites. Suggest that extensive polycylic aromatic sheets are found in all three extracts.
Report 74 amino acids in the Murchison meteorite.
Review of theories about origin of organic material in carbonaceous chondrites; favors view that organic molecules from interstellar clouds were incorporated into parent body and then subjected to aqueous processes.
Review of organic chemistry of Murchison carbonaceous chondrite.
Report finding amino acids and sugars in the Bruderheim and Murray stones, distributed differently from on earth. However, say that for theoretical reasons, these results should be attributed to either an abiogenic origin or to contamination.
Compares terrestrial and extraterrestrial organic material spectra. Skeptical of biogenic theories of origin.
Synthesize various substances including phosphonic acid, which is found in the Murchison carbonaceous chondrite, by UV irradiation of orthophosphorous acid in presence of various simple organic compounds such as formaldehyde.
A review of organic and prebiotic substances in comets.
Paramagnetic resonance study of Cold Bokkeveld, Mighei, and Nogoya carbonaceous chondrite free radicals, which are called partly attributable to a biogenic origin.
Argues against the probability of life arising on comets, or likelihood of liquid water having existed on them.
Argue that spectroscopic data provide no evidence for the existence of grains in interstellar space, and an absorption band they would produce is not seen.
Report that three micron spectrum of deuterium-rich ``polymer'' extracted from Orgueil matches the galactic center infrared source IRS7 better than it does terrestrial kerogen. Argue that about half the carbon in the Orgueil stone therefore must come from interstellar organic grains.
Report that the three-micron spectrum of Orgueil is almost identical to that of the infrared source IRS7 near the galactic center, suggesting that organic macromolecules in meteorites are the same as in interstellar space.
Isotopic measurements suggest that parent body of Orgueil and Ivuna carbonaceous chondrites was undergoing aqueous activity from very early in the history of the solar system.
Reports finding apparently indigenous amino acids in Murchison carbonaceous chondrite which, however, are non-racemic. (suggests biology, although the authors avoid saying this.)
Isotopic analysis establishes extraterrestrial origin of amino acids on Murchison carbonaceous chondrite. The fact that there is an asymetry between optical isomers suggests optically active materials predate existence of life.
Reports finding unusual ratio of isotopes in amino and carboxylic acids from the Murchison carbonaceous chondrite, confirming their extraterrestrial origin and suggesting they formed in interstellar clouds.
Attacks works of Lipman, attributing bacteria to terrestrial contamination.
Observed the same structures as Nagy et al, but believe them to be the same as certain known particles made of inorganic materials. Since fossils made of these particular materials would be ``unprecedented,'' they reject biological theory.
Similar to Fitch, et al., 1962.
Argue that some of Nagy et al's organic elements are ragweed pollen particles, distorted in the staining process.
An international popular-science bestseller which made extraterrestrial life an accepted topic of conversation among educated people in the XIX Century; carbonaceous chondrites are invoked as strong circumstantial evidence for life on other planets.
A popular article in support of Thomson's meteorite panspermia theory.
Reports monocarboxylic acids in Murray and Murchison carbonaceous chondrites. The lack of preference for an even number of carbons suggests extraterrestrial (non-biological) origin.
Reports discovery of heterocyclic compounds indigenous to the Murchison meteorite.
Report 4-hydroxypyrimidnes and other heterocyclic compounds extracted from Murray, Murchison, and Orgueil carbonaceous chondrites. No biological N-heterocyclics or triazines observed.
Discuss organic grains discovered near Comet Halley. Speculate they are related to the kerogenlike substance in carbonaceous chondrites.
News story about discovery of organic materials in comets Halley and Wilson.
Fischer-Tropsch experiments using meteoritic and terrestrial irons as catalyst produced small amount of hydrocarbons, none isoprenoid.
E. Gelpi, et al., 1970 Geochimica et Cosmochimica Acta 34:981.
Report finding normal and isoprenoid alkanes in extracts from six carbonaceous chondrites.
E. Gelpi, et al., 1970 Geochimica et Cosmochimica Acta 34:995.
Find small amounts of normal and isoprenic alkanes in Canyon Diablo, Odessa, and Cosby's Creek irons. Distribution is similar to carbonaceous chondrites; doubt they are indigenous, however, because most near the surface of nodule.
Report mass spectroscopic analysis of isoprenoids and other isomeric alkanes from numerous meteorites, including Canyon Diablo irons, and compare with terrestrial samples. Conclude that these are probably biogenic, but are contaminants from dust, air, auto exhaust, or smoke stack plumes. Allende carbonaceous chondrite, newly fallen, shows no such activity.
Argues that the Moon once had oceans, and that life may have evolved there; asks if rings of dark material around edge of lunar mountains are fossils left as seas dried.
Proposes a mechanism--molecular tunneling in condensed formaldehyde--by which formaldehyde polymers could form in interstellar space as postulated by Wickramasinghe.
Low temperature molecular tunneling processes in formaldehyde, such as the author suggested occur in interstellar clouds, could perhaps also lead to life on cold interstellar grains.
Synthesize various substances including phosphonic acid, which is found in the Murchison carbonaceous chondrite, by UV irradiation of orthophosphorous acid in presence of various simple organic compounds such as formaldehyde.
Attack both Wickramasinghe-Hoyle and Chyba-Sagan models of Comet Halley, in favor of their own theory in which organics are formed by photoprocessing of dust. State that of the two, the Chyba-Sagan model is slightly better.
Argue infrared spectra of interstellar dust, laboratory organic residues, and meteorites are similar to each other and show a composition arguably like Comet Halley's.
Attempts to identify objects seen by Nagy as pollen or plant spores.
Reports an unsuccessful search for organic structures in thin sections of Kaba and Cold Bokkeveld stones.
Claims to have identified algae-like plant fossils in various rocks, including the Knyahinya ordinary chondrite and the Toluca iron.
Examined 20 meteorites, none of which were carbonaceous chondrites. Claimed to have found fossils of sponges, corals, and crinoids, especially in the Knyahinya ordinary chondrite. Considers possibility that meteorites are of catastrophic terrestrial origin (i.e. sedimentary rocks blasted into space) but prefers the extraterrestrial theory.
Finds that human skin is a major source of amino acid contamination of analytical samples in general.
Find clearly biological organic material in the Pueblito de Allende carbonaceous chondrite. Attribute it to contamination and question, given rapidity of this contamination in a well-docuemented fall, all studies of meteorite organic contents.
Identifies purines and other organic nitrogen compounds in Orgueil sample. Large amounts of sym-triazine derivatives, of no biological significance, are noted.
Fails to confirm Nagy's report of high optical rotation in Orgueil sample.
Scattered light leads to spurious large optical rotations; this is probably what Nagy reported.
Report use of Fischer-Tropsch type reaction to synthesize many of the compounds found in carbonaceous chondrites.
Report discovery of organic nitrogen compounds in Murchison carbonaceous chondrite: purines and triazines, contrary to Folsome's results (Folsome, 1971 and 1973), but failed to detect 4-hydroxypyrimidines reported by Folsome.
Reports discovery of various phenolic acids and other organic acids in the Murchison carbonaceous chondrite.
Report discovery of carbynes in Allende carbonaceous chondrite.
Extremely thorough review of all organic chemical analyses of meteorites 1900-1965, excluding specifically exobiological claims.
Originally published in German edition of a book by William Thomson. Defends the future Lord Kelvin's philosophy of science and his stance on various issues, ranging from Weber's electrodynamics and the particle theory of light to panspermia, against criticism of J.K.F. Zöllner. Argues that meteoritic life could survive entry into the atmosphere if it were deep enough in the stone or if it gently blew off the surface before the stone reached the denser part of the atmosphere. Remarks that he independently proposed this idea a year before Kelvin.
Attempt to determine number of nucleotide changes in comet-borne virus evolution and expected genetic distance between strains in successive epidemics. Conclude Hoyle and Wickramasinghe model disagrees with observation.
Propose experiments for future space missions which could resolve biological questions about comets.
Report discovery of porphyrins similar to those in ancient terrestrial sediment.
Report discovery of porphyrin pigments in Orgueil, Murray, Cold Bokkeveld, and Mokoia carbonaceous chondrites. No evidence of bacterial or other contamination found. The fluorescence spectra differ from those of terrestrial samples.
Antarctic meteorite ALH77306, a carbonaceous chondrite, contains a low level of racemic amino acids. The organic content of the stone on pyrolysis resembles the Murchison carbonaceous chondrite.
Review article on exobiology.
Show theoretically that physical conditions in prestellar molecular clouds favor formation of grains coated with complex organic materials, including amino acids; identify the grains with carbonaceous chondrite inclusions.
Argue that interstellar grains are found in gas clouds and in carbonaceous chondrites; that they are made of organic materials; and that life may have originated from a polymer coating such a grain.
Claim that spectra of gasclouds revel presence of polysaccharides.
Popular presentation of argument for comet-borne disease, alluding to Nagy's carbonaceous chondrite findings as evidence.
Popular account of his theory, emphasizing the role of interstellar clouds.
One of the most radical of their works, attacking most forms of biological evolution as involving unbelievably small probabilities and advocating instead directed panspermia by an ancient extraterrestrial civilization. Also suggest that insects, flowers, etc. appeared on Earth via meteorites.
Present the original, more moderate form of their theory for a popular audience: comets are vectors by which microorganisms are transmitted from interstellar space to the Earth.
Attempt to provide technical support for the epidemiological aspects of panspermia.
Rebuttal to Henderson, et al.,1987. Say they do not claim every influenza virus is from a different comet, or that viruses invade Earth more than once a decade. What establishment biologists call ``evolutionary changes in the virus'' they see as changes in host immune response instead.
Response to Kissel and Krüger, 1987. Deny that they claimed all cometary dust must be biological. Question whether Vega spacecraft observations are reliable, or might have destroyed the molecules being sought. Point out many of Kissel and Krüger's comments assume a particular model of comet structure.
Kissel and Krüger reply: Vega also didn't find the right quantities of sodium and potassium for life, or even for nucleic acids, so it doesn't matter if molecules were destroyed by impact.
Object to a statement by Chyba and Sagan that the agreement between bacterial model and later measurement provides ``no evidence'' that their theory is true. Say that Chyba and Sagan abiotic model is a far worse violation of the Occam's razor principle than anything of which they are guilty: life, after all, is a well-known phenomenon, but who has ever seen complex pre-biological chemistry, much less biogenesis?
Argue that Comet Halley's dust spectrum data agree with their bacterial model better than with the abiotic model of Chyba and Sagan, although both have difficulties at short wavelengths/low fluxes.