Engineering topics

Labotka, T. C.

Publications and source records attributed to Labotka, T. C..

5 records

NASA NTRS1986

Application of shuttle imaging radar to geologic mapping

Images from the Shuttle Imaging Radar - B (SIR-B) experiment covering the area of the Panamint Mountains, Death Valley, California, were examined in the field and in the laboratory to determine their usefulness as aids for geologic mapping. The covered area includes the region around Wildrose Canyon where rocks ranging in age from Precambrian to Cenozoic form a moderately rugged portion of the Panamint Mountains, including sharp ridges, broad alluviated upland valleys, and fault-bounded grabens. The results of the study indicate that the available SIR-B images of this area primarily illustrate variations in topography, except in the broadly alluviated areas of Panamint Valley and Death Valley where deposits of differing reflectivity can be recognized. Within the mountainous portion of the region, three textures can be discerned, each representing a different mode of topographic expression related to the erosion characteristics of the underlying bedrock. Regions of Precambrian bedrock have smooth slopes and sharp ridges with a low density of gullies. Tertiary monolithologic breccias have smooth, steep slopes with an intermediate density of gullies with rounded ridges. Tertiary fanglomerates have steep rugged slopes with numerous steep-sided gullies and knife-sharp ridges. The three topographic types reflect the consistancy and relative susceptibility to erosion of the bedrock; the three types can readily be recognized on topographic maps. At present, it has not been possible to distinguish on the SIR-B image of the mountainous terrain the type of bedrock, independent of the topographic expression.

Labotka, T. C.↗

NASA NTRS1984

Quantitative use of multiincidence-angle SAR for geologic mapping

It is proposed that techniques be developed and used for quantitative interpretation of shuttle imaging radar-B (SIR-B) data for lithologic identification and mapping. The use of backscatter versus incidence angle signatures derived from SIR-B images is to be investigated. The use of SIR-B with other sensors for geologic mapping is also to be considered. Anticipated results are discussed in terms of geologic mapping.

Farr, T. G.↗

NASA NTRS1980

Howardites - Samples of the regolith of the eucrite parent-body: Petrology of Frankfort, Pavlovka, Yurtuk, Malvern, and ALHA 77302

Modal petrographic methods have been applied to the meteorites Frankfort, Pavlovka, Yurtuk, Malvern, and ALHA 77302, to determine some of the characteristics of the regolith of the eucrite parent body. Lithic clasts in the meteorites fall into three major groups: pyroxene + plagioclase rocks, orthopyroxenites, and fused-soil clasts. Lithic clasts make up a small proportion of the soil; mineral clasts from orthopyroxenites dominate the coarse-grained fraction; and the fine-grained fraction contains minerals from both orthopyroxenites and plagioclase + pyroxene rocks. The eucrite regolith appears to have the following characteristics: the source rocks are friable, the soils are immature, comminution is the major soil-forming process, and the soil is well mixed.

Labotka, T. C.↗

NASA NTRS1980

The lunar regolith - Comparative petrology of the Apollo sites

A description is presented of the modal petrology of eight surface soils from the Apollo 11, 12, 14, 15, and 16 landing sites. One of the most striking features of the petrology of the considered soils is found to be the similarity in distribution of pyroxene composition between the soil and the local rock types. The considered investigation is concerned with certain difficulties with respect to an understanding of regolith evolution. Lunar soils contain material foreign to the local geology. The foreign material must have been transported over long distances. However, models of regolith formation on the moon indicate that lateral transport is inefficient. It is found in the investigation that the soil is predominantly of local derivation, that lateral homogenization is a minor process, that foreign material is present in the amounts indicated by bulk chemical mixing models, and that preferential transport of fine-grained material does not occur.

Labotka, T. C.↗

NASA NTRS1979

The Apollo 17 drill core - Petrologic systematics and the identification of a possible Tycho component

Modal data support a five-unit stratigraphy for the Apollo 17 drill core. The upper unit E (0-22 cm depth) is marked by high content of fused soil, brown glass, and mare basalt fragments. This unit corresponds with a portion of the core excavated and refilled within the last 2 m.y. The underlying unit D (22071 cm depth) has a low abundance of fused soil (i.e., low maturity) and is rich in coarse (less than 200 microns) mare fragments. A large section of the core, unit C (71-224 cm depth), is finer-grained, more mature (richer in agglutinates), more feldspathic and has more highland lithic, mineral and glass fragments than unit D. The next underlying unit, B (224-256 cm depth), has yellow/colorless KREEP glasses with a high Si, low-alkali composition unlike the common Apollo 15 or Apollo 17 KREEP series. The petrologic (fused soil) and Is/FeO maturity of this layer is also lower than the units above and below. The deepest unit, A (256-284 cm depth), is marked by its relatively higher maturity and lower yellow/colorless KREEP glass content. The most prominent petrographic/stratigraphic indicators are the pyroxene-rich immature mare unit D and the abundance of KREEP glass in unit B. This KREEP glass is distinctive petrographically and compositionally, and is probably exotic to the Apollo 17 site. It is suggested here that the KREEP glass in unit B is derived from Tycho, which implies widespread distribution of KREEP on the lunar nearside.

Vaniman, D. T.↗