Search NASA⌕ Search

Engineering topics

Bild, R. W.

Publications and source records attributed to Bild, R. W..

9 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Germanium abundances in lunar basalts - Evidence of mantle metasomatism?

To fill in gaps in the present Ge database, mare basalts were analyzed for Ge and other elements by RNAA and INAA. Mare basalts from Apollo 11, 12, 15, and 17 landing sites are rather uniform in Ge abundance, but Apollo 14 aluminous mare basalts and KREEP are enriched in Ge by factors of up to 300 compared to typical mare basalts. These Ge enrichments are not associated with other siderophile element enrichments and thus are not due to differences in the amount of metal segregated during core formation. Based on crystal-chemical and interelement variations, it does not appear that the observed Ge enrichments are due to silicate liquid immiscibility. KREEP basalt source regions may have been metasomatized, and Apollo 14 aluminous mare basalt magmas may have become enriched in Ge by interacting with these metasomatized areas. The presence of volatile- and Ge-rich regions in the moon suggest that the moon was never totally molten.

Dickinson, T.↗
NASA NTRS1978

Experimental investigations of trace element fractionation in iron meteorites. I - Early results

Experimental procedures for measuring trace element partitioning among metal and sulfide and silicate phases are described, and solid metal/liquid metal partition coefficients for minor and trace elements in the Fe-Ni system at 5 to 14% Ni are reported. The bulk compositions desired are homogenized at superliquidus temperature for 15-24 hours, held at a temperature in the solid/liquid two phase region for about 24 hours, and quenched to freeze in the equilibrium compositions. Run products are analyzed by electron microprobe. With the exception of Cr, all preliminary partition coefficients obtained are in the same sense as values derived from iron meteorites. The partition coefficients for Cr in solid metal/liquid metal and metal/troilite systems suggest that IIIAB and main group pallasites equilibrated with 9-22% troilite. A second method which makes it possible to place upper and lower limits on the partition coefficient by holding part of the sample at subliquidus and part at superliquidus temperatures, yielded significantly different results for the two metals tested (Au and Pt) from those obtained by the first method, demonstrating the importance of a close approach to equilibrium before using experimentally-determined partition coefficients to test empirical differentiation models for iron meteorites.

Bild, R. W.↗
NASA NTRS1977

Four new iron meteorite finds

Four new iron meteorites are described: Buenaventura (IIIB) from Chihuahua, Mexico: mass 114 kg; Denver City (anomalous) from Texas, USA: mass 26.1 kg; Kinsella (IIIB) from Alberta, Canada: mass 3.7 kg; and Tacoma (IA) from Washington, USA: mass 17 g. Denver City is unique - i.e., not related to any other known iron. Tacoma is the smallest iron meteorite recorded. The meteorites were initially discovered in 1969, 1975, 1946, and between 1925 and 1932, respectively.

Scott, E. R. D.↗
NASA NTRS1976

Trace element evidence regarding a chondritic component in howardite meteorites

The concentrations of siderophiles Ni, Ge, Ru, Ir, and Au and volatiles Zn, Ga, Cd, and In in howardite meteorites were determined and are discussed along with similar data for eucrites and diogenites. The concentrations of the chondritic component in howardites are remarkably high. The concentrations in four high-siderophile howardites are comparable to those found in mature soils from the lunar highlands. The amounts of excess volatiles are roughly consistent with those expected if the chondritic component resemble CI, CM, or E4 chondrites. Evidence indicates that the howardite parent body had a radius of several hundred kilometers, and the most probable formation location was 1-2 AU from the sun.

Chou, C.-L.↗
NASA NTRS1974

Mesosiderites. I - Compositions of their metallic portions and possible relationship to other metal-rich meteorite groups

The metal from 17 mesosiderites has been analyzed for Ni, Ga, Ge, and Ir by the techniques of atomic-absorption spectrometry and neutron activation. Most mesosiderite metal samples fall in a narrow compositional range: Ni, 7.0-9.0%; Ga, 13-16 ppm; Ge, 47-58 ppm; and Ir, 2.4-4.4 ppm. Most of those falling outside these ranges belong to Powell's (1971) least-metamorphosed type. Mesosiderite metal falls in the same general composition range as IIIAB irons, IIIE irons, pallasites and H-group chondrite metal. There are distinct differences in detail, however, and firm evidence for a close genetic relationship between any of these groups and the mesosiderites is lacking.

Wasson, J. T.↗
NASA NTRS1974

Volatile-element systematics and green glass in Apollo 15 lunar soils

A number of volatiles in Apollo 15 soils correlate with each other and with decreasing distance from the Apennine Front. These correlations can be understood in terms of a deposition of green glass and cogenetic volatiles on the flanks of the Front followed by addition of secondary magmatic volatiles including excess Ar-40. Mixing of these materials with mare-type regolith resulted in the observed volatile-element patterns. The absence of an increase in siderophilic element content with decreasing distance from the Front probably resulted from the failure of the steeply sloping front to develop a highlands-type mature regolith. Breccia 15015 has a siderophilic element signature typical of a mature Apollo 15 soil, which tends to rule out its transport to the site as part of an Autolycus or Aristillus ray.

Chou, C.-L.↗
NASA NTRS1973

Extralunar materials in cone-crater soil 14141.

Radiochemical neutron activation analysis has been used to determine Ni, Zn, Ga, Ge, Cd, In, Ir, and Au in duplicate samples of lunar soil 14141 and in one additional replicate each of soils 14163 and 14259. The concentrations of extralunar trace elements Ni, Ge, Ir, and Au in 14141 and 14163 are, respectively, about 69 and 82% as high as those in 14259. Although most of the mass of 14141 appears to be ejecta from Cone Crater, a sizable contamination by mature Fra Mauro soil such as 14259 is also present. The siderophilic-element concentrations of the subregolith Fra Mauro materials are estimated to be 25 plus or minus 25% of those observed in 14259.

Wasson, J. T.↗