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At least 883 records · Page 49
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Vegetation and soil backscatter over the 4-18 GHz region

Using an FM-CW radar mounted atop a truck-mounted boom, 4-8 GHz backscatter spectral data was gathered during the 1972 growing season at incidence angles of 0-70 deg in 10 deg steps for each of the four linear polarization combinations. The data covers four mature crop types (corn, milo, soybeans and alfalfa) and bare ground taken under a wide range of soil and plant moisture contents. To insure statistical representation of the results, measurements were conducted over 147 fields corresponding to a total of about 50,000 data points. During 1973, a higher frequency version of the above system was used to collect additional data over the 8-18 GHz frequency region. This paper presents a summary of the results and suggests design criteria for future radar remote sensing missions.

Ulaby, F. T.↗
NASA NTRS1974

Simulation of lunar carbon chemistry. II - Lunar winds contribution

Simulation experiments, computations, and analysis of glassy agglutinates show that a directly condensed lunar wind vapor phase is strongly depleted in carbon and sulfur compounds and may recrystallize rapidly in the lunar thermal cycle and separate from host crystals. Factors preventing identification of low-energy species implanted from the lunar atmosphere are discussed. Computational results indicate that the implanted lunar winds carbon originates both from the vapor phases injected into the lunar atmosphere during thermal metamorphism of mature lunar soil grains and from direct volatization of impacting micrometeorites. It is suggested that microglass splashes and tiny crystalline grains possibly attached to the surface of coarser grains do not affect the characteristics of solar wind carbon chemistry in the lunar soil.

Bibring, J. P.↗
NASA NTRS1974

Loss of oxygen, silicon, sulfur, and potassium from the lunar regolith

The processes of formation and maturation of lunar soils lead to enrichments in the heavy stable isotopes of oxygen, silicon, sulfur, and potassium. The isotopic enrichment implies substantial losses of these elements from the moon. Vaporization by micrometeorite impact and by ion sputtering have removed at least 1% of the mass of the regolith. The losses of sulfur and potassium amount to at least 20-30% of their original abundance in the regolith.

Clayton, R. N.↗
NASA NTRS1974

The distribution in lunar soil of hydrogen released by pyrolysis

The hydrogen contents of various Apollo 15 rocks and Apollo 15 and 16 soil particle types and sieve fractions have been determined by the pyrolysis method. The Apollo 15 crystalline rocks analyzed release very little hydrogen (approximately 6 micromoles H/g sample). The mineral, glass, and light-colored breccia fragments in the soils contain approximately 5, 30, and 10 micromoles H/g sample, respectively. The dark breccias and glassy agglutinates examined have much higher hydrogen contents (60 and 110 micromoles H/g sample). For soil particle diameters less than 105 microns, hydrogen content increases linearly with particle surface area per particle mass. The calculated grain surface average concentrations of hydrogen in the Apollo 15 and 16 soils fall short of experimentally determined saturation values by a factor of 20. The volume-correlated component of hydrogen in a soil increases with the maturity of the soil.

Desmarais, D. J.↗
NASA NTRS1975

Origin and evolution of the lunar regolith; Proceedings of the Symposium, Houston, Tex., November 13-15, 1974

The papers consider the origin and evolution of the lunar regolith utilizing data obtained during American and Soviet manned and unmanned lunar missions as well as surface and orbital observations, photography, sample collections, and experimental studies. Topics include the transport and emplacement of crater and basin deposits, development of the mare regolith, the shallow lunar structure as determined from the passive seismic experiment, horizontal transport of the regolith, the origin of the exotic component and KREEP-rich materials, the influx of interplanetary materials onto the moon, stratification in the lunar regolith, catastrophic rupture of lunar rocks, cosmic-ray exposure ages of surface features, breccia formation by sintering and crystallization, evolution of the lunar soil, and effects of maturation on the reflectance of the regolith. Individual items are announced in this issue.

Source record↗
NASA NTRS1975

Track view of the regolithic elephant

Information gained from track studies in lunar soils is reviewed. Soil maturity indices are compared and briefly discussed. Track methods to establish the layering chronology of lunar cores are also treated.

Crozaz, G.↗
NASA NTRS1975

Apollo Soyuz Test Project Weights and Mass Properties Operational Management System

The Apollo Soyuz Test Project (ASTP) Weights and Mass Properties Operational Management System was established to assure a timely and authoritative method of acquiring, controlling, generating, and disseminating an official set of vehicle weights and mass properties data. This paper provides an overview of the system and its interaction with the various aspects of vehicle and component design, mission planning, hardware and software simulations and verification, and real-time mission support activities. The effect of vehicle configuration, design maturity, and consumables updates is discussed in the context of weight control.

Collins, M. A., Jr.↗
NASA NTRS1975

Lunar soil and surface processes studies

Glass particles in lunar soil were characterized and compared to terrestrial analogues. In addition, useful information was obtained concerning the nature of lunar surface processes (e.g. volcanism and impact), maturity of soils and chemistry and heterogeneity of lunar surface material. It is felt, however, that the most important result of the study was that it demonstrated that the investigation of glass particles from the regolith of planetary bodies with little or no atmospheres can be a powerful method for learning about the surface processes and chemistry of planetary surfaces. Thus, the return of samples from other planetary bodies (especially the terrestrial planets and asteroids) using unmanned spacecraft is urged.

Glass, B. P.↗
NASA NTRS1975

Mapping of the wildland fuel characteristics of the Santa Monica mountains of Southern California

LANDSAT digital data was successfully used to map and evaluate the wildland fuels of the Santa Monica Mountains in Southern California. A mixed classification scheme was used where training areas of known vegetation types were entered and the maximum likelihood classifier run, followed by an evaluation of the results and an unsupervised retraining of the classifier using an image of the probability of misclassification. Estimation of maturity class and crown closure percents of the major cover types were assigned to each computer class by associating the photointerpretation of 159 large scale photo samples with the resultant computer classes using analysis of variance and analysis of categorized data. The result of the computer classification and statistical analysis were then transformed from the LANDSAT Coordinate California State Plane Coordinate system for use in a digital format in the FIRESCOPE data retrieval and fire modeling system.

Nichols, J. D.↗
NASA NTRS1976

Results from the Crop Identification Technology Assessment for Remote Sensing (CITARS) project

The author has identified the following significant results. It was found that several factors had a significant effect on crop identification performance: (1) crop maturity and site characteristics, (2) which of several different single date automatic data processing procedures was used for local recognition, (3) nonlocal recognition, both with and without preprocessing for the extension of recognition signatures, and (4) use of multidate data. It also was found that classification accuracy for field center pixels was not a reliable indicator of proportion estimation performance for whole areas, that bias was present in proportion estimates, and that training data and procedures strongly influenced crop identification performance.

Bauer, M. E.↗
NASA NTRS1975

Crop identification technology assessment for remote sensing (CITARS). Volume 10: Interpretation of results

The CITARS was an experiment designed to quantitatively evaluate crop identification performance for corn and soybeans in various environments using a well-defined set of automatic data processing (ADP) techniques. Each technique was applied to data acquired to recognize and estimate proportions of corn and soybeans. The CITARS documentation summarizes, interprets, and discusses the crop identification performances obtained using (1) different ADP procedures; (2) a linear versus a quadratic classifier; (3) prior probability information derived from historic data; (4) local versus nonlocal recognition training statistics and the associated use of preprocessing; (5) multitemporal data; (6) classification bias and mixed pixels in proportion estimation; and (7) data with differnt site characteristics, including crop, soil, atmospheric effects, and stages of crop maturity.

Bizzell, R. M.↗
NASA NTRS1975

Orientational anisotropy in infant vision

Infants prefer to look at horizontal and vertical gratings rather than at oblique gratings only when they are at or near threshold spatial frequencies, as would be expected if acuity for oblique edges is lower than that for horizontal and vertical edges. That such a bias exists as early as 6 weeks of age suggests that the orientational asymmetry of the visual system depends on endogeneous maturation rather than exposure to a carpentered world.

Cohen Leehey, S.↗
NASA NTRS1975

Integrated investigation of the mixed origin of lunar sample 72161,11

The comminution-agglutination model and the solar-wind implantation-retention model are used to postulate the origins of the particulate components of lunar sample (72161,11), a submillimeter fraction of a surface sample for the dark mantle regolith at LRV-3. Grain-size analysis was performed by wet sieving with liquid argon, and analyses for CO2, CO, CH4, and H2 were carried out by stepwise pyrolysis in a helium atmosphere. The results indicate that the present sample is from a mature regolith, but the agglutinate content is only 30% in the particle-size range between 90 and 177 microns, indicating an apparent departure from steady state. Analyses of the carbon, methane, and hydrogen concentrations in size fractions larger than 149 microns show that the volume-correlated component of these species increases with increased grain size. It is suggested that the observed increase can be explained in terms of mixing of a dominant local population of coarser agglutinates having high carbon and hydrogen concentrations with an imported population of finer agglutinates relatively poor in carbon and hydrogen.

Basu, A.↗
NASA NTRS1976

Interorganizational transfer of technology - A study of adoption of NASA innovations

The paper describes a study on the effects of top management support, various techno-economic factors, organizational climate, and decision-making modes on the adoption of NASA innovations. Field research consisted of interviews and questionnaires directed to sixty-five organizations. Forty-five test cases where different decisions for adoption of ideas for new products or processes were made on NASA Tech Briefs were studied in relation to the effects of various factors on the degree of success of adoption, including: (1) the degree of general connection of the technology to the firm's existing operation, (2) the specificity of the relationship between the technology and some existing and recognized problem, (3) the degree of urgency of the problem to which the technology was related, (4) maturity of technology available to implement the technology, (5) availability of personnel and financial resources to implement the technology, (6) degree of top management interest, (7) the use of confrontation in joint-decision, (8) the use of smoothing in decision-making, and (9) the use of forcing in decision-making. It was found that top managements interest was important in the product cases only, and that the success of process innovations was dependent on the quality of information and the specificity of the relationship between the technology and some recognized existing problem.

Chakrabarti, A. K.↗
NASA NTRS1976

The Space Transportation System

The Space Transportation System, consisting of the Space Shuttle, Spacelab, and the Space Tug, is discussed from the viewpoint of reductions in the cost of space operations. Each of the three vehicles is described along with its mission capabilities, and the time table for system development activities is outlined. Basic attributes of the Space Transportation System are reviewed, all operational modes are considered, and the total cost picture of the system is examined from the standpoint of a mission economic analysis. It is concluded that as the features of the Space Transportation System, especially the Shuttle and the Tug, are put to more efficient use during the maturing-operation phase, the total cost of conducting space missions should be about half of what it would be if any other system were employed.

Donlan, C. J.↗
NASA NTRS1975

Sporulation and ultrastructure in a late Proterozoic cyanophyte - Some implications for taxonomy and plant phylogeny

Electron microscopical studies of a morphologically diverse, coccoid, presumably late Proterozoic blue-green alga are here reported. They show, together with light microscopy, that the form studied is widespread in the Cordilleran geosyncline, extend the record of well-defined endosporangia perhaps 700 million years into the past, and reveal previously unrecorded ultrastructural details. Coming from northeastern Utah, southwestern Alberta, and east central Alaska, these minute fossils belong to the recently described, morphologically diverse taxon Sphaerocongregus variabilis Moorman, are related to living entophysalidaceans, and have affinities with both the chroococcalean and chamaesiphonalean cyanophytes. Included in the morphological modes displayed by this alga are individual unicells, coenobial clusters of unicells, and a range of endosporangia comparable to those described for living entophysalidaceans. Scanning and transmission electron microscopy reveal that the endospores are commonly embedded in a vesicular matrix, that some of them show what appears to be a bilaminate or perhaps locally multilaminate wall structure, and that some remain together to mature as coenobial clones or 'colonies'. Taxonomic classification and phylogeny are discussed.

Cloud, P.↗
NASA NTRS1975

Results from the crop identification technology assessment for remote sensing /CITARS/ project

The CITARS (Crop Identification Technology Assessment for Remote Sensing) task design, objectives, and results are reviewed along with relevant conclusions and recommendations. The principal assessment concern crop identification performance for corn and soybeans in six sites in Illinois and Indiana. Use of quantitative measures of classification performance and statistical evaluations of the results have been important parts of the technology assessment. Relation of crop and sensor characteristics is discussed. Factors affecting crop identification performance are identified as crop maturity and site characteristics, type of single-date automatic data processing procedure used for local recognition, nonlocal recognition with and without processing for extension of recognition signatures, and use of multidate or multitemporal data. In particular, the probability of correct classification of field center pixels is not well correlated and thus is not a reliable indicator of proportion estimation performance.

Bizzell, R. M.↗
NASA NTRS1976

Mercury - Spectral reflectance measurements /0.33-1.06 microns/ 1974/75

The spectral reflectance (0.32-1.06 microns) of Mercury was measured during two elongations, September-October 1974 and March 1975. The spectra are much improved over the previously available measurements. The reflectance increases almost linearly with wavelength, and no electronic transition absorption bands are evident to the precision of the data. The new spectra agree very well with the reflectance of mature lunar mare and upland soils and are not similar to those of any other observed solar system object. This suggests that the surface materials and the weathering processes controlling their optical properties are similar for both the moon and Mercury. Differences between the spectra for the two-observation periods may indicate differences in the average composition for the different regions of Mercury observed.

Vilas, F.↗