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At least 199 records · Page 11

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NASA NTRS1972

Application of ecological, geological and oceanographic ERTS-1 imagery to Delaware's coastal resources planning

The author has identified the following significant events. Coastal vegetation species appearing in the ERTS-1 image taken of the Southern Coast of Delaware, during orbit 333 on August 16, 1972, have been correlated with ground truth vegetation maps, and imagery obtained from high altitude RB-57 and U-2 overflights. The vegetation maps of the entire Delaware Coast were prepared using data collected on foot, in small boats, and from low altitude aircraft. Multispectral analysis of high altitude RB-57 and U-2 photographs indicated that five vegetation species could be clearly discriminated from 60,000 feet altitude, including: (1) salt marsh cord grass (Spartina alterniflora); (2) salt marsh hay and spike grass (Spartina patens and Distichlis spicata); (3) reed grass (Phragmites communis); (4) high tide bush and sea myrtle (Iva species and Baccharus halimifolia); and (5) a group of fresh water species found in impounded areas built to attract water fowl. Major Spartina alterniflora and Spartina patens communities within the tidal marshes can be identified in the ERTS-1 imagery. Phragmites, and other species however, occur in smaller, more dispersed groupings and are difficult to discriminate within the resolution capability of the ERTS-1 scanner. Similarly, major impounded areas, built to attract water fowl can be detected; however, mosquito drainage ditches, covering many of Delaware's marshes, are too narrow and not long enough to be resolved by ERTS-1 sensors. High-marsh and dune communities dominated by high tide bush (Iva frutescens) and sea myrtle (Baccharus halimifolia) can be distinguished from adjacent maritime forest and beach grass communities.

Klemas, V.↗

NASA NTRS1970

The use of multispectral sensing techniques to detect ponderosa pines trees under stress from insects or diseases

The detection of stress induced by bark beetles in conifers is reviewed in two sections: (1) the analysis of very small scale aerial photographs taken by NASA's RB-57F aircraft on August 10, 1969, and (2) the analysis of multispectral imagery obtained by the optical-mechanical line scanner. Underexposure of all films taken from the RB-57 aircraft and inadequate flight coverage prevented drawing definitive conclusions regarding optimum scales and film combinations to detect the discolored infestations. Preprocessing of the scanner signals by both analog and digital computers improved the accuracy of target recognition. Selection and ranking of the best channels for signature recognition was the greatest contribution of digital processing. Improvements were made in separating hardwoods from conifers and old-kill pine trees from recent discolored trees and from healthy trees, but accuracy of detecting the green infested trees is still not acceptable on either the SPARC or thermal-contouring processor. From six years of experience in processing line scan data it is clear that the greatest gain in previsual detection of stress will occur when registered multispectral data from a single aperture or common instantaneous field of view scanner system can be collected and processed.

Heller, R. C.↗

NASA NTRS1973

Identification of marsh vegetation and coastal land use in ERTS-1 imagery

Coastal vegetation species appearing in the ERTS-1 images taken of Delaware Bay on August 16, and October 10, 1972 have been correlated with ground truth vegetation maps and imagery obtained from high altitude RB-57 and U-2 overflights. The vegetation maps of the entire Delaware Coast were prepared during the summer of 1972 and checked out with ground truth data collected on foot, in small boats, and from low-altitude aircraft. Multispectral analysis of high altitude RB-57 and U-2 photographs indicated that five vegetation communities could be clearly discriminated from 60,000 feet altitude including: (1) salt marsh cord grass, (2) salt marsh hay and spike grass, (3) reed grass, (4) high tide bush and sea myrtle, and (5) a group of fresh water species found in impoundments built to attract water fowl. All of these species are shown in fifteen overlay maps, covering all of Delaware's wetlands prepared to match the USGS topographic map size of 1:24,000.

Klemas, V.↗

NASA NTRS1972

Thermal volatilization studies on lunar samples.

The results of thermal volatilization studies on lunar basalts, breccias, and soils, carried out to measure the depletion of selected elemental abundances during heating under vacuum, are evaluated. The kinetics of K, Rb, and Pb loss are found to be sufficiently fast to permit vaporization and loss of these elements during the production of impact glasses. There is little probability that lunar basalt flows have lost a significant percentage of K, Rb, and Na by volatilization, unless the flow is extensively stirred. The uniformly low Na concentrations of mare basalts cannot be attributed to post eruption vaporization and loss on Na.

Gibson, E. K., Jr.↗

NASA NTRS1973

Abundance of 17 trace elements in carbonaceous chondrites.

Seventeen trace elements (Ag, Au, Bi, Br, Cd, Cs, Ge, In, Ir, Rb, Re, Sb, Se, Te, Tl, U, and Zn) were measured by neutron activation analysis in eight C1 samples (1 Alais, 3 Ivuna, 4 Orgueil and in three C2 samples (one each of Mighei, Murchison, Murray). The results show far less scatter than earlier literature data. The standard deviation of a single measurement from the mean of eight C1 samples lies between 2 and 14%, except for the following four elements: Au, Ag, Rb, and Br. The first two probably reflect contamination and sample heterogeneity, the last two, analytical error. Apparently C1 chondrites have a far more uniform composition than some authors have claimed.

Kraehenbuehl, U.↗

NASA NTRS1974

The application of ERTS-1 data to the land use planning process

Land resource data has been extracted on a percent of cell basis from ERTS imagery, RB-57 color infrared imagery and best available conventional sources for a 10,000 square kilometer test area in eastern Wisconsin. First, the data from the three sources is compared on a spatial basis for a 300 square kilometer portion of the test area. For those land resource variables associated with cover, ERTS derived resource data compared favorably with both the RB-57 and conventional data. Second, the effect of the data source on land use decisions is examined. Three interstate highway corridors are located through the same region based upon data extracted from each of the three sources. A policy of preserving natural environmental systems was used as a basis for the corridors selection in each case. The resulting three corridors compare favorably.

Clapp, J. L.↗

NASA NTRS1974

Isotopic evidence for a terminal lunar cataclysm

Most highland total rock samples define a single U-Pb isochron which corresponds to a metamorphism age of about 3.9 aeons. This age is also obtained for internal U-Pb isochrons for some of these samples. The data on 18 rock samples range from concordant samples with U-238/Pb-206 ratio of about 1.2 to discordant ones with U-238/Pb-206 ratio of about 0.02. This feature, coupled with a correlated pattern of U-238/Pb-204 ratios, indicates that Pb was extensively mobilized at about 3.9 aeons. The observed Pb-U fractionation is essentially due to Pb volatilization during the metamorphic events. Volatile Pb transport is not accompanied by similar effects in Rb and must therefore be attributed to a specific process. Rb-Sr internal isochrons for the same rocks determine distinct metamorphic events in the interval 3.85 to 4.00 aeons. It is concluded that highland samples from widely separated areas bear the imprint of an event or series of events in a narrow time interval which can be identified with a cataclysmic impacting rate of the moon at about 3.9 aeons, although diffrentiation by internal magma generation cannot be excluded.

Tera, F.↗

NASA NTRS1974

On the age of the Onverwacht Group, Swaziland sequence, South Africa

Some rocks of the Onverwacht Group, South Africa, have been analyzed for Rb and Sr concentrations and Sr isotopic composition. These rocks include volcanic rocks, layered ultramafic differentiates and cherty sediments. Whole rock data indicate that the Rb-Sr isotopic systems in many samples were open and yield no reasonable isochron relationships. However, the data of mineral separates from a basaltic komatiite define a good isochron of 3.50 (plus or minus .2) b.y. with an initial Sr-87/Sr-86 ratio of 0.70048 plus or minus 5. The orthodox interpretation of this age is the time of the low grade metamorphism. It is reasonable to assume that the age of 3.50 b.y. might also represent the time of initial Onverwacht volcanism and deposition. The initial Sr-87/Sr-86 ratio obtained above is important to an understanding of the Sr isotopic composition of the Archean upper mantle.

Jahn, B.-M.↗

NASA NTRS1974

Resource inventory for multi-agency watershed planning

A demonstration study showed that NASA high-altitude color infrared (RB-57) imagery is useful for providing timely, relatively inexpensive, and accurate land-use information. The inventory encompassed 18 land-use categories for a 2590-square-kilometer Michigan watershed. The RB-57 photography was compared to alternative data collection methods (including ERTS and Skylab) and was found to have superior cost effectiveness for providing the desired information.

Enslin, W. R.↗

NASA NTRS1975

76535 - An old lunar rock

Measurements of Rb-Sr systematics, K-Ar gas retention ages, and the isotopic compositions of He, Ne, and Ar have been performed for lunar troctolite 76535. Other investigators have presented evidence that this important rock formed as a cumulate at depth, which would make it an important link in the early chronology of the moon. Rb-Sr data do not define an isochron. Total Ar-40/K ages of whole rock and plagioclase range from 4.40-4.54 b.y. The trapped Ne and Ar in 76535 cannot be uniquely characterized as either 'planetary derived' or solar wind derived, but appear to have characteristics of both. The data suggest that 76535 formed 4.3-4.6 b.y. ago, and the accumulation process and/or subsequent annealing may have incorporated excess noble gases. Separation of radiogenic parents and daughters with incomplete isotopic equilibration may also have occurred during cooling or during a subsequent 'event'.

Bogard, D. D.↗

NASA NTRS1975

Skylab imagery: Application to reservoir management in New England

The author has identified the following significant results. S190B imagery is superior to the LANDSAT imagery for land use mapping and is as useful for level 1 and 2 land use mapping as the RB-57/RC8 high altitude imagery. Detailed land use mapping at levels 3 and finer from satellite imagery requires better resolution. For evaluating factors that are required to determine volume runoff potentials in a watershed, the S190B imagery was found to be as useful as the RB-57/RC8 high altitude aircraft imagery.

Cooper, S.↗

NASA NTRS1975

Application of remote sensing technology to land evaluation, planning utilization of land resources, and assessment of wildlife areas in eastern South Dakota

A soils map for land evaluation in Potter County (Eastern South Dakota) was developed to demonstrate the use of remote sensing technology in the area of diverse parent materials and topography. General land use and soils maps have also been developed for land planning LANDSAT, RB-57 imagery, and USGS photographs are being evaluated for making soils and land use maps. LANDSAT fulfilled the requirements for general land use and a general soils map. RB-57 imagery supplemented by large scale black and white stereo coverage was required to provide the detail needed for the final soils map for land evaluation. Color infrared prints excelled black and white coverage for this soil mapping effort. An identification and classification key for wetland types in the Lake Dakota Plain was developed for June 1975 using color infrared imagery. Wetland types in the region are now being mapped via remote sensing techniques to provide a current inventory for development of mitigation measures.

Source record↗

NASA NTRS1976

Hyperfine spectroscopy using transverse modulated optical pumping

Population inversion is observed between the field-independent ground hyperfine states of Rb-87 when using an optical pumping technique which is applicable to a large number of species of atoms and ions. Inversion occurs upon a coherent transfer of angular momentum to the Rb-87 spin system from circularly polarized light propagating in a transverse direction to a magnetic field. Coherence is established by modulating, at certain frequencies, the light intensity or magnetic-field strength.

Hughes, W. M.↗

NASA NTRS1976

Superconducting critical fields of alkali and alkaline-earth intercalates of MoS2

Results are reported for measurements of the critical-field anisotropy and temperature dependence of group-VIB semiconductor MoS2 intercalated with the alkali and alkaline-earth metals Na, K, Rb, Cs, and Sr. The temperature dependences are compared with present theories on the relation between critical field and transition temperature in the clean and dirty limits over the reduced-temperature range from 1 to 0.1. The critical-field anisotropy data are compared with predictions based on coupled-layers and thin-film ('independent-layers') models. It is found that the critical-field boundaries are steep in all cases, that the fields are greater than theoretical predictions at low temperatures, and that an unusual positive curvature in the temperature dependence appears which may be related to the high anisotropy of the layer structure. The results show that materials with the largest ionic intercalate atom diameters and hexagonal structures (K, Rb, and Cs compounds) have the highest critical temperatures, critical fields, and critical-boundary slopes; the critical fields of these materials are observed to exceed the paramagnetic limiting fields.

Woollam, J. A.↗

NASA NTRS1976

Chronology of the early lunar crust

The Rb-Sr systematics of lunar 'anorthositic' rocks was studied in an effort to understand the evolution of the lunar crust. The contamination by KREEP of the anorthositic crust is corrected using chemical mixing models; cumulate geochemical models are used to establish the chronology of the early lunar crust; a method is presented to derive an estimate of the Rb/Sr ratio of the moon. A mathematical model for the Rb-Sr evolution of the lunar crust that includes mare basalt genesis is presented.

Schonfeld, E.↗

NASA NTRS1977

The history of the Apollo 17 Station 7 boulder

Rb-Sr and Sm-Nd methods were used to determine the age of the dark dikelets 77075 cutting the 4.36 b.y. noritic breccia 77215 of the Station 7 boulder of Apollo 17. A regression line corresponding to an age of 4.07 plus or minus 0.09 b.y. is obtained with an Rb-87 decay constant of 1.41 x 10 to the -11th/yr and an initial Sr-87/Sr-86 ratio of approximately 0.69918. It is noted that the intrusion age of the dikelets provides the most reliable criterion for determining the age of the entire boulder, i.e., the boulder is not an extension of 77115, which formed more recently. Attention is given to a generalized lunar history during the first 600 m.y.

Nakamura, N.↗

NASA NTRS1979

The origin of KREEP

KREEP is a lunar material having very high concentrations of incompatible elements; its name is an acronym for the incompatibles K, rare-earth elements (REE), and P. Although a few pristine (endogenously igneous) KREEPy samples were returned from the Apollo 15 and 17 sites, most KREEPy samples are polymict breccias. Most models of KREEP petrogenesis have been based on partial melting of a variety of sources. Such models fail to explain the veritable absence of variations in incompatible element patterns over the sampled portion of the moon. We have defined a KREEP component based on the average composition of Apollo 14 breccias having extremely high concentrations of incompatible elements. Normalization of accurate incompatible data for KREEPy samples from the Apollo 12, 14, 15, 16, and 17 sites to this component virtually always shows no resolvable fractionation (e.g., <10% variation in the La/Lu ratio), whereas partial melting models typically produce larger fractionations (±20–25% in La/Lu) from a factor of 2 difference in degree of partial melting. Required is a single major source that could provide KREEP to widely separated locations on the nearside of the moon. The anorthositic crust of the moon is commonly attributed to the flotation of plagioclase on a deep, moon-wide magma ocean. Fractional crystallization of this magma ocean would have produced large enrichments of incompatibles in a residual liquid. No other plausible major source of incompatibles has been proposed. We borrow the German prefix ur—meaning primeval and designate this residual liquid ‘urKREEP.’ We propose that all KREEPy rocks originated by dilution of urKREEP with crustal or mantle materials during assimilation, or zone-refining (pristine samples), or impact-induced brecciation (breccias and melt rocks). The formation of urKREEP cannot be dated precisely. Correction of breccia Rb-Sr model ages for Rb loss or gain during the early intense bombardments yields ages that cluster in the range 4.4–4.5 Gy. This implies that crystallization of the magma ocean was essentially complete at this time and is in general agreement with U-Pb evidence indicating crustal formation at 4.4 Gy. Assuming that the moon had the composition of an H-group chondrite depleted in Fe-Ni and FeS and that half the incompatibles fractionated into materials other than urKREEP, the thickness of a moon-wide urKREEP layer was <2 km. Thorium concentrations determined by gamma ray spectroscopy indicate that about 4% of the incompatibles in an H chondritic moon are now in the outermost kilometer.

Paul H. Warren↗

NASA NTRS1979

Ar-40/Ar-39 age of the Shergotty achondrite and implications for its post-shock thermal history

Ar-40/Ar-39 measurements are used to determine the age of the Shergotty achondrite and the chronology of the shock event responsible for the complete conversion of its plagioclase to maskelynite is discussed. Apparent ages are found to vary between 240 and 640 million years for the whole rock sample, with a plateau age of 254 million years for a maskelynite separate. The Rb-Sr age of 165 million years determined by Nyquist at al (1978) suggests that the maskelynite as well as the whole rock was incompletely degassed. Argon diffusion characteristics indicate a post-shock cooling time greater than 1000 years and a burial depth greater than 300 m for a thermal model of a cooling ejecta blanket of variable thickness. It is concluded that the shock event which degassed the argon and reset the Rb-Sr systematics occurred between 165 and 250 million years ago when the parent body experienced a collision in the asteroid belt.

Bogard, D. D.↗