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Anders, E.

Publications and source records attributed to Anders, E..

At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Mars and earth - Origin and abundance of volatiles

An investigation is conducted concerning the factors which are responsible for the tenuous nature of the Martian atmosphere in comparison to the terrestrial atmosphere, taking into account new data obtained in connection with the Viking missions. It is found that Mars was poor in volatiles from the start and fell further behind earth by less complete outgassing, by extensive retrapping, and by the partial loss of lighter gases. Attention is given to noble gases on earth and Mars, the condensation of noble gases and other volatiles, the sources of earth's volatiles, the bulk composition of earth, the release of volatiles from earth, clues to the volatile endowment of Mars, an abundance table for Mars, a comparison of terrestrial and Martian conditions, isotopic data on noble gases, xenon-129 on Mars and earth, possibilities concerning the loss of an early Martian atmosphere, the evolution of the atmosphere of Mars, conditions in the case of planet Venus, and the reasons for the poorness of small planets in volatiles.

Anders, E.↗
NASA NTRS1977

Origin of organic matter in the early solar system. VII - The organic polymer in carbonaceous chondrites

Degradation techniques, including pyrolysis, depolymerization, and oxidation, were used to study the insoluble polymer from the Murchison C2 chondrite. Oxidation with Cr2O7(2-) or O2/UV led to the identification of 15 aromatic ring systems. Of 11 aliphatic acids identified, three dicarboxylic acids presumably came from hydroaromatic portions of the polymer, whereas eight monocarboxylic acids probably derive from bridging groups or ring substituents. Depolymerization with CF3COO4 yielded some of the same ring systems, as well as alkanes (C1 through C8) and alkenes (C2 through C8), alkyl (C1 through C5) benzenes and naphthalenes, and methyl- or dimethyl -indene, -indane, -phenol, -pyrrole, and -pyridine. All these compounds were detected below 200 C, and are therefore probably indigenous constituents. The properties of the meteoritic polymer were compared with the properties of a synthetic polymer produced by the Fischer-Tropsch reaction. It is suggested that the meteoritic polymer was also produced by surface catalysis.

Hayatsu, R.↗
NASA NTRS1977

'Mysterite' - A late condensate from the solar nebula

An attempt is made to clarify the nature of 'mysterite', a material that had been postulated to explain the overabundance of Tl, Bi, and Ag in certain chondrites. Four dark clasts and a vein sample from the H6 chondrite Supuhee were analyzed by radiochemical neutron activation analysis for Ag, Au, Bi, Br, Cd, Cs, Ge, In, Ir, Ni, Os, Rb, Re, Sb, Se, Te, Tl, and Zn. One of the clasts is enriched in all volatile elements, while the other four samples are enriched only in the siderophile volatiles Ag, Bi, and Tl. The enrichments range up to 100 times typical H6 chondrite abundances. The proportions of Ag, Bi, and Tl suggest the presence of at least two, Tl-rich and Tl-poor, varieties of mysterite. The former seems to dominate in Supuhee and Krymka, and the latter in Mezo-Madaras. Apparently mysterite is a late condensate from the solar nebula that collected volatiles left behind by earlier generations of chondrites. It was incorporated in Supuhee and perhaps in other chondrites (mainly of low petrologic types) during brecciation events.

Higuchi, H.↗
NASA NTRS1977

Chemical compositions of the moon, earth, and eucrite parent body

Model compositions of the moon and earth were calculated on the assumption that these planets had experienced chondrite-like nebular fractionation processes. The model correctly predicts the abundance ratios of certain volatile/refractory element pairs (e.g., Cd/Ba, Ga/La, Sn/Th, and Pb/U), the density of the moon, and the major rock types. The model is also used to reconstruct the composition of the parent eucrite body, which resembles the moon except for a lower content of refractory elements.

Anders, E.↗
NASA NTRS1977

Rochechouart meteorite crater - Identification of projectile

Ten samples from the 20-km Rochechouart crater in France have been analyzed for the siderophile elements Ir, Os, Re, Au, Pd, Ni, and Ge by radiochemical neutron activation analysis. The up to 1000-fold enrichment of siderophiles correlates with shock effects, increasing in the following order from least to greatest: basement rocks, glass-free breccias, glassy breccias, impact melts. The abundance pattern of the meteorite was determined from interelement correlations. Several samples fell off the correlation lines, presumably due to recrystallization and weathering of impact glasses during the approximately 165-m.y. age of the crater. The most reliable diagnostic elements were Os, Ir, Ni, and Pd; their abundance ratios suggest that the Rochechouart meteorite was a IIA iron.

Janssens, M.-J.↗
NASA NTRS1977

Noble gases in separated meteoritic minerals - Murchison /C2/, Ornans /C3/, Karoonda /C5/, and Abee /E4/

The distribution of all five noble gases was measured in four meteorites of different classes by mass spectrometry and stepwise heating of HCl-HF-insoluble residues and of samples treated with HNO3 and atomic oxygen. The distribution of the gases among the three main phases, chromite, polymer, and the ill-defined Q-phase, was determined, and also the isotopic distribution of the gases in the phases was obtained.

Srinivasan, S.↗
NASA NTRS1977

Gas-rich minerals in the Allende meteorite - Attempted chemical characterization

A ten-step etching experiment with HNO3 was performed on a chromite-carbon residue from Allende, in order to characterize the HNO3-soluble minor phase 'Q' that contains most of the primordial Ar, Kr, and Xe. Each etch fraction was analyzed by neutron activation analysis for Cr, Fe, Co, Ir, and Au. The results suggest that Q consists of two minerals, each comprising about 5 per cent of the residue. Phase Q1, of Fe/Cr ratio greater than 20, is soluble in cold dilute HNO3 and seems to contain most of the heavy noble gases. It may be an HCl-insoluble sulfide of nominal composition (Fe84Ni12Cr4)Sx. Phase Q2, of Fe/Cr ratio about 0.5 and somewhat enriched in Co, is slowly soluble in hot concentrated HNO3 and seems to be at least an order of magnitude poorer in heavy noble gases than Q1. It may be daubre-elite or an acid-soluble variety of chromite.

Gros, J.↗
NASA NTRS1977

Meteoritic material on the moon

Three types of meteoritic material are found on the moon: micrometeorites, ancient planetesimal debris from the "early intense bombardment," and debris of recent, craterforming projectiles. Their amounts and compositions have been determined from trace element studies. The micrometeorite component is uniformly distributed over the entire lunar surface, but is seen most clearly in mare soils. It has a primitive, C1-chondrite-like composition, and comprises 1 to 1.5 percent of mature soils. Apparently it represents cometary debris. The ancient component is seen in highland breccias and soils. Six varieties have been recognized, differing in their proportions of refractories (Ir, Re), volatiles (Ge, Sb), and Au. All have a fractionated composition, with volatiles depleted relative to siderophiles. The abundance patterns do not match those of the known meteorite classes. These ancient meteoritic components seem to represent the debris of an extinct population of bodies (planetisimals, moonlets) that produced the mare basins during the first 700 Myr of the moon's history. On the basis of their stratigraphy and geographic distribution, five of the six groups are tentatively assigned to specific mare basins: Imbrium, Serenitatis, Crisium, Nectaris, and Humorum or Nubium.

Morgan, J. W.↗
NASA NTRS1977

Lunar basins and craters - Evidence for systematic compositional changes of bombarding population

Of the 33 lunar samples considered in the investigation, 31 came from the North Ray Crater. The relationship between meteoritic component and rock type is studied. There appears to be some correlation between the meteoritic component, as given by the Ir/Au ratio, and the rock type, as given by the U content. The relation of ancient meteoritic components to basins and craters is examined, taking into account the resolution of groups, the relative ages from clast-matrix relations, assignments to specific basins or craters, and the relation between meteoritic components and Woenke's 'primary matter'. A table shows seven meteorite-free samples which are all low-alkali cataclastic anorthosites, or anorthositic clasts in light-matrix breccias. The origin of ancient meteoritic bodies are also investigated. The latest data strengthen earlier conclusions that the basin-forming objects were genetically related to the moon.

Hertogen, J.↗
NASA NTRS1976

Chemical fractionations in meteorites. X - Ureilites

An investigation involving the measurement of 17 trace elements in 4 ureilites was conducted with the objective to obtain information for the characterization of the two components of the ureilites. The groundmass of the mineral is an olivine-clinopyroxene rock which is presumably the residue left after partial melting of a more primitive precursor. This ultramafic rock is permeated by a network of veins containing diamond, graphite, nickel-iron, and primordial noble gases. Attention is given to the vein material, the origin of the vein material, the 'constant' siderophile component and ultramafic rock, and questions concerning the origin of ureilites.

Higuchi, H.↗
NASA NTRS1976

Chemical fractionations in meteorites. IX - C3 chondrites

Radiochemical neutron activation is applied to the analysis of four C3V chondrites and three C3O chondrites for 17 trace elements (U, Re, Ir, Ni, Au, Sb, Ge, Ag, Rb, Cs, Bi, Tl, Br, Se, Te, In, and Cd). It is shown that both classes exhibit a typical chondritic step pattern, reflecting loss of volatiles during chondrule formation. It appears that the H2S/H2 ratio is the key variable to account for the condensation of chalcophile elements as a function of H2S. C3O's seem to have condensed in a region where enough metallic Fe was present to buffer the H2S pressure, whereas C3V's condensed in a more oxidized region where H2S was in excess. Accretion temperatures for both subclasses is determined. Sb and Au show variable depletion, presumably reflecting variable loss during chondrule formation.

Anders, E.↗
NASA NTRS1976

Composition of the projectiles that bombarded the lunar highlands

Twenty highland samples from Apollo 14, 15, and 17 and the eucrites Juvinas and Morre County were analyzed by radiochemical neutron activation for Ag, Au, Bi, Br, Cd, Cs, Ge, In, Ir, Ni, Os, Pd, Rb, Re, Sb, Se, Te, Tl, U, and Zn. The meteoritic components of 82 highland rocks were recalculated with the new corrections for the indigenous contribution and were classified by discriminant and cluster analysis as well as ternary diagrams, using Ir, Re, Au and Ni as diagnostic elements. To characterize these groups more fully, average abundances of meteoritic volatiles (Sb, Ge, Ag, Se, Te, and Bi) were calculated from regressions against Ir.

Gros, J.↗
NASA NTRS1975

Host phase of a strange xenon component in Allende

A description is presented for the isolation and characterization of the host phase from the Allende C3V chondrite and a mass spectrometric study of the five noble gases in this phase. It is though that the Xe component may have been produced by spontaneous fission of an extinct superheavy element. The fission Xe resides in a minor fraction comprising 0.5% of the meteorite. The fraction consists of chromite, an unknown Cr, Fe-mineral, and amorphous carbon. The gas components and the progenitor of the fission Xe may have been trapped in these minerals when they formed from the solar nebula.

Lewis, R. S.↗
NASA NTRS1975

Extinct superheavy element in the Allende meteorite

Radiochemical neutron activation analysis of seven Allende samples for 26 trace elements were conducted. In addition, Cr and Fe were studied with the aid of instrumental neutron activation analysis. The investigation had the objective to identify the extinct superheavy element which was present in meteorites and decayed to Xe isotopes by spontaneous fission. The superheavy element was found to reside mainly in a rare mineral (probably a Fe, Ni, Cr, Al-sulfide), comprising only 0.04% of the meteorite. It is pointed out that of the nine volatile superheavy elements 111 to 119, only 115, 114, and 113 are expected to condense as sulfides in the temperature interval between 400 and 500 K corresponding to mineral formation conditions in the solar nebula.

Anders, E.↗