Engineering topics

Lauer, H. V., Jr.

Publications and source records attributed to Lauer, H. V., Jr..

48 records · Page 3

NASA NTRS1991

UV, visible, and near-IR reflectivity data for magnetic soils/rocks from Brazil

The objective is to obtain UV, visible, and near-IR reflectivity spectra for several magnetic Brazilian soils/rocks and compare them to corresponding data for Mars to see if these materials satisfy both magnetic and spectral constraints for Mars. Selected physical properties of the magnetic Brazilian soils/rocks are presented. In general, the spectral features resulting from ferric crystal-field transitions are much better defined in the spectra of the magnetic Brazilian soils/rocks than in Martian spectral data. Presumably, this results from a relatively higher proportion of crystalline ferric oxides for the former. The apparent masking of the spectral signature of maghemite by hematite or goethite for the Brazilian samples implies the magnetic and spectral constraints for Mars can be decoupled. That is, maghemite may be present in magnetically-significant but optically-insignificant amounts compared to crystalline hematite.

Vempati, R. K.↗

NASA NTRS1991

Synthesis and properties of Ti-substituted goethites and hematites

The objective was to synthesize Ti-substituted goethites and hematites and to characterize them using x-ray diffraction, thermogravimetric analysis, coulimetry, optical and Mossbauer spectroscopies, and magnetic data in order to determine the evidence of Ti substitution for Martian spectral data. Evidence is provided that up to 4 mole percent can be incorporated into the goethite structure during the low temperature synthesis. Because the spectral data in the visible and near-IR are not sensitive to the degree of Ti-substitution in goethites and hematites, such data cannot be used to infer the presence or absence of Ti substitution in Martian hematites and goethites.

Vempati, R. K.↗

NASA NTRS1989

Maturity and geochemistry of the Van Serg core (79001/2) with implications for micrometeorite composition

The soil maturity and the concentration of Fe metal and 18 major and trace elements were determined along the length of the 79001/2 double drive tube collected near the Van Serg crater at the Apollo 17 station 9. Samples from the top 8.5 cm of the core are found to be very mature and to be enriched in Fe metal and siderophile elements compared to soil lower in the core. It is suggested that this enrichment may have resulted from a significant exposure at some time in the past. A soil component of metallic Fe may be related to micrometeorite impact.

Morris, R. V.↗

NASA NTRS1985

Spectral and other physicochemical properties of submicron powders of hematite (alpha-Fe2O3), maghemite (gamma-Fe2O3), magnetite (Fe3O4), goethite (alpha-FeOOH), and lepidocrocite (gamma-FeOOH)

The spectral properties (0.35-2.20 microns) of submicron powders of hematite, maghemite, magnetite, goethite, and lepidocrocite are determined. Other physicochemical data are obtained for the powders in order to determine if deviations from stoichiometry occur due to their small particle size, to determine their state of chemical and phase purity, and to determine the physical characteristics of the individual powders. The physicochemical data obtained include mean particle diameter, discrete particle shape, chemical composition, crystallographic phase, magnetic parameters, and Moessbauer parameters. The positions of the spectral features for the hematite, maghemite, and magnetite powders are independent of temperature over the interval between about +20 and -110 C. For the goethite and lepidocrocite powders, a small shift of about 0.02 micron to shorter wavelengths is observed for some of the features after cooling to about -110 C. The spectral properties of the iron oxides and oxyhydroxides are important not only for understanding the basic physics and chemistry of the compounds but also for applications such as the remote sensing of the earth and Mars.

Morris, R. V.↗

NASA NTRS1984

Stratigraphy and geochemistry of the Stone mountain core (64001/2)

Ferromagnetic resonance and magnetic data measured on both sections of the double drive tube cord 64001/2 collected on Stone mountain, station four, Apollo 16 are reported, along with instrumental neutron activation analysis data measured on the lower section. These data provide insight into the depositional and irradiational history and the geochemical provenances of the core.

Korotev, R. L.↗

NASA NTRS1982

Effect of aluminum substitution on the reflectance spectra of hematite

Hematite and aluminous hematite were synthesized and the diffuse reflectance spectra were recorded for the region between 0.35 and 1.20 microns. Results show that the near-IR based minimum for the aluminous hematite is shifted longward by about 0.02 microns and is much more shallow. Also, the aluminous specimen is considerably more reflective shortward of approximately 0.55 microns where the ferritic specimen is strongly absorbing. This is noteworthy since the visible slope and the red shoulder are often used in the construction of false color and band ratio images.

Morris, R. V.↗

NASA NTRS1982

The Apennine Front core 15007/8 - Irradiational and depositional history

The Apennine Front core 15007/8 was subjected to ferromagnetic resonance (FMR), magnetic and noble gas measurements. Ferromagnetic resonance intensity I(s)/FeO surface exposure (maturity) index values and FeO concentrations are reported for 0.5 cm depth intervals, and noble gas and FMR data are given for 13 soils and two clasts selected from various depths in the 57 cm-long core. These data indicate four core units whose contacts are at about 18, 49 and 55 cm. The 0-18 cm unit has cosmogenic Xe-131/Xe-126 values that are higher than underlying soil and indicate irradiation at depths greater than 50 cm, showing it to probably be the ejecta from the crater on whose rim the core was collected. The 18-49 cm unit has relatively constant I(s)/FeO values and cosmogenic gas abundances, and may represent a mixed soil zone. I(s)/FeO drops by 30 units at the 49-cm contact. Comparison of the 15007/8 core to other ones suggests that soils on slopes tend to be mixed and to not contain units with long in situ radiation profiles.

Bogard, D. D.↗

NASA NTRS1981

Stability of goethite /alpha-FeOOH/ and lepidocrocite /gamma-FeOOH/ to dehydration by UV radiation - Implications for their occurrence on the Martian surface

The geochemistry of the FeOOH polymorphs is an important consideration when evaluating the likelihood of an occurrence of detectable amounts of these minerals on Mars. An investigation is conducted regarding the stability of the FeOOH polymorphs geothite and lepidocrocite to dehydration in the presence of UV radiation. A thorough characterization of the FeOOH powders used in the laboratory experiments is presented, and the irradiational facility and experimental procedures are described. The results obtained in the conducted experiments are discussed. It is found that there is as yet no basis in laboratory experiments for inferring that perceptible UV photodehydration of FeOOH polymorphs will occur naturally on the surface of Mars on a time scale of at least 10-100 years.

Morris, R. V.↗

NASA NTRS1980

The case against UV photostimulated oxidation of magnetite

The kinetics of magnetite oxidation in O2-bearing atmospheres in the presence of electromagnetic radiation was studied. No perceptible oxidation of magnetite by ultraviolet (UV) photostimulation occurred. These results do not corroborate previous conclusions by Huguenin (1973, 1974) as to the occurrence of this process. Therefore, although the possibility that the process actually occurs cannot be ruled out, it is concluded that there is not yet a basis in laboratory experiments for inferring that UV photostimulated oxidation of magnetite occurs naturally on the surface of Mars.

Morris, R. V.↗

NASA NTRS1979

Characterization and depositional and evolutionary history of the Apollo 17 deep drill core

With a depth resolution of about 0.5 cm, the stratigraphy of the approximately 3 m Apollo 17 deep drill core by measurement of the total FeO concentration is characterized along with the FMR surface exposure (maturity) index Is/FeO, the metallic iron concentration Fe-vsm, and the FMR linewidth delta-H. For stratigraphic characterization, the first two parameters are the most important. Most of the core is characterized by a FeO concentration of approximately 15.5 wt. %; there is a more mafic zone in the upper approximately 75 cm where the maximum FeO concentration is approximately 18.5 wt. %, and a more felsic zone between approximately 225 and 260 cm where the minimum FeO concentration is approximately 14.0%. As indicated by Is/FeO, most of the soil in the core is submature to mature; the only immature zone is located between approximately 20 and 60 cm and is one of the most distinctive features in the core. A two stage model for the depositional and evolutionary history of the Apollo 17 deep drill core is proposed: (1) deposition by one event approximately 110 m.y. ago or deposition by a sequence of closely spaced events initating a maximum of approximately 200 m.y. ago and terminating approximately 110 m.y. ago, (2) in situ reworking (gardening) to a depth of approximately 26 cm in the period between approximately 110 m.y. ago and the present day.

Morris, R. V.↗

NASA NTRS1978

Depositional and surface exposure history of the Shorty Crater core 74001/2 - FMR and magnetic studies

Surface exposure (maturity) indices and concentrations of FeO and metallic iron were determined at 0.5-cm intervals of the Apollo 17 core section, which sampled a pyroclastic deposit on the rim of Shorty Crater. The determinations showed that all of the soil in the core is extremely immature. An exposure history of the core is proposed: accumulation (about 3.6 billion years ago), shallow burial (during the first 20 million years), deep burial (till about 10-15 million years ago), followed by excavation (10-15 million years ago), and in situ reworking (till the present).

Morris, R. V.↗

NASA NTRS1977

Redox equilibria of multivalent ions in silicate glasses

Experimental studies were made on the compositional dependence of the redox equilibrium of Eu in synthetic silicate liquids, together with an empirical model describing the observed compositional dependence. Electron paramagnetic resonance (EPR) was used to measure the concentration ratio of Eu(2+) to Eu(3+) in various glasses formed by rapidly quenching silicate liquids. The compositional field studied comprised mixtures of SiO2, TiO2, Al2O3, CaO, MgO, and Na2O. The proposed model describes the Eu(2+)/Eu(3+) ratio over the entire compositional field in terms of parameters easily related to each glass composition. The general applicability and utility of the model is further demonstrated by its application to the Fe(2+)-Fe(3+), Ce(3+)-Ce(4+), and Cr(3+)-Cr(6+) redox reactions in binary alkali oxide silicate glasses of Li, Na, and K.

Lauer, H. V., Jr.↗