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Singer, R. B.

Publications and source records attributed to Singer, R. B..

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Gaussian analysis of temperature effects on the reflectance spectra of mafic minerals in the 1-micron region

Gaussian band-fitting analysis has been applied to the reflectance spectra of mafic silicates, which are of geologic importance throughout much of the solar system. Reflectance spectra obtained over a sample temperature range of about 80 to 448 K of olivine, clinopyroxene, and orthopyroxene were used in order to characterize the spectral changes in the 1-micron wavelength region of these minerals as a function of temperature. Four Gaussians are required to characterize the olivine, while two Gaussians are necessary to characterize both the orthopyroxene. The trends of the individual Gaussian parameters (integrated area, width, and center position) are presented as a function of temperature for each mineral. The characterization by Gaussian analysis of the 1-micron absorption feature of all minerals yields consistent trends in center position, integrated area, and width that may prove useful in quantitative determination of these minerals in mineral mixtures.

Roush, T. L.↗
NASA NTRS1986

The removal of atmospheric effects from remotely sensed near-infrared spectral data

A technique has been developed for removing atmospheric effects from high-resolution remotely sensed 0.7-2.5-micron spectral data. This calibration technique relies solely on the raw spectra data for calibration information. Results are presented for a set of reflectance spectra for rock samples obtained at a distance of about 0.5 km using an InSb spectrophotometer. The calibration technique uses the depths of water-vapor absorption bands in the remotely obtained spectral data to estimate the degree to which atmospheric attenuation has affected these data.

Blake, P. L.↗
NASA NTRS1985

Effects of temperature on remotely sensed mineral absorption features

The present paper provides the results from a series of laboratory experiments which were conducted to investigate the variable spectral behavior of diagnostic Fe(++) crystal field absorptions in common rock-forming minerals as a function of temperature. The general goal of the study is to refine existing techniques of mineralogic and chemical characterization, based on specific optical behavior which has been measured and correlated in a systematic way. It is pointed out that the presented work, taken together with a number of recent studies, provides new information on the manner in which specific features of mafic minerals combine in rocks and soil spectra, taking into account also variations of identification and subsequent interpretation as a function of planetary surface temperature. The obtained results are directly applicable to interpretation of remotely sensed data for many solar system objects, particularly Mars, asteroids, the moon, earth, and Mercury.

Singer, R. B.↗
NASA NTRS1985

Position Paper: Workshop on Geologic Applications of Remote Sensing to the Study of Sedimentary Basins

The utility of LANDSAT Multispectral Scanner (MSS) and Thematic Mapper (TM) data for providing regional coverage has been demonstrated. Information derived from LANDSAT spectral data is varied, but has primarily been used for distinguishing materials in a scene. Because of the limited number and width of the MSS and TM bands, LANDSAT data has only limited utility for actual identification of materials. The new advanced sensors (currently airborne, but eventually shuttle-based) have more limited areal extent than LANDSAT, but greater spatial and spectral resolution. The Airborne Imaging Spectrometer (AIS) has spectral resolution of about .01 microns and, typically, has 10m/pixel spatial resolution. This improved spectral resolution means that diagnostic spectral features may now be identified, which in turn means that actual identification of mineral phases present can be addressed (of either monominerallic or composite materials). Another new sensor, the Thermal Infrared Multispectral Scanners (TMS), obtains data in the 8 to 12 micron range. The information from the various sensors (e.g., LANDSAT, AIS, and TIMS) is complementary, covering different wavelength regions and consequently sensitive to different materials or physical properties of materials. In addition, the new sensors also produce a higher volume of data, which must be cleverly and efficiently handled.

Blake, P. L.↗
NASA NTRS1985

Multisensor Data Integration Techniques

The availability of data from sensors operating in several different wavelength regions had led to the development of new techniques and strategies for both data management and image analysis. Work is ongoing to develop computer techniques for analysis of integrated data sets. These techniques include coregistration of multisensor images, rectification of radar images in areas of topographic relief to ensure pixel to pixel registration with planimetric data sets, calibration of data so that signatures can be applied to remote areas, normalization of data acquired with disparate sensors and determination of extended spectral signatures of surface units. In addition, software is being developed to analyze coregistrated digital terrain and image data so that automated stratigraphic and structural analyses can be performed. These software procedures include: strike and dip determination, terrain profile generation, stratigraphic column generation, stratigraphic thickness measurements, structural cross-section generation, and creation of 3-D block diagrams. These techniques were applied to coregistered LANDSAT 4 Thematic Mapper (TM), Thermal Infrared Multispectral Scanner (TIMS), and multipolarization synthetic aperture radar (SAR) data of the Wind River Basin in Wyoming.

Evans, D. L.↗
NASA NTRS1985

Multispectral Analysis of the Kasei Vallis-lanae Planum Region of Mars

The surficial geology of the Kasei Vallis - Lunae Planum region of Mars was investigated using the three color Viking Orbiter 1 data. Spatial resolution is 820m and Ls = 100 deg, a season of low atmospheric and and surface dustiness. This region was chosen for high quality color and thermal inertia data as well as for the diversity of volcanic plains and fluvial landform. The data was reformatted to Mercator projection and calibrated to normal reflectance using in flight calibration parameters and observed photometric properties. Color properties from this image are displayed in two forms: the Red Albedo vs. Violet Albedo two dimensional histogram, and representative 3 point spectra. Virtually the full range of regolith color properties known from prior research is represented, plus some new characteristics. Interpretations of the data are presented which address general composition and formation processes of channel and intracrater deposits.

Singer, R. B.↗
NASA NTRS1985

First Direct Detection of Clay Minerals on Mars

Magnesian clays or clay-type minerals were conclusively detected in the martian regolith. Near-IR spectral observations of Mars using the Mauna Kea 2.2-m telescope show weak but definite absorption bands near microns. The absorption band positions and widths match those produced by combined OH stretch and Mg-OH lattice modes and are diagnostic of minerals with structural OH such as clays and amphiboles. Likely candidate minerals include serpentine, talc, hectorite, and sponite. There is no spectral evidence for aluminous hydroxylated minerals. No distinct band occurs at 2.55 microns, as would be expected if carbonates were responsible for the 2.35 micron absorption. High-albedo regions such as Elysium and Utopia have the strongest bands near 2.35 microns, as would be expected for heavily weathered soils. Low-albedo regions such as Iapygia show weaker but distinct bands, consistent with moderate coatings, streaks, and splotches of bright weathered material. In all areas observed, the 2.35-micron absorption is at least three times weaker than would be expected if well-crystallized clay minerals made up the bulk of bright soils on Mars.

Singer, R. B.↗
NASA NTRS1985

Spectroscopic observation of Mars

A review is given of what is known about the surface of Mars from reflectance spectroscopy, including some new results and providing an overview of the principles involved. While some form of bound water and/or OH has been known on Mars for many years, a new result presented is the identification of structural OH in a dilute or poorly crystalline magnesian clay. The detection of water ice in the residual north polar cap is noted. Also considered is the role that reflectance spectroscopy will play in the future, from earth and as an important part of the NASA Mars Geosciences/Climatology Orbiter mission.

Singer, R. B.↗
NASA NTRS1985

Sensitivity of current remote sensing instrumentation to diagnostic spectral features in geologic materials

The capability of some current remote sensing instruments to discriminate and identify geologic materials based on spectral reflectance in the visible and near-IR (0.4-2.6 microns) are studied. Laboratory reflectance spectra of selected geologic materials were convolved to the bandpasses of the Landsat 4 Thematic Mapper and the Shuttle Multispectral InfraRed Radiometer. As a secondary goal, spectral parameters which are particularly useful for exploring specific geological problems have been identified, as a guide both to the design of future sensors having a limited number of bandpasses, as well as to aid efficient analysis of large three-dimensional data sets returned by imaging spectrometers.

Singer, R. B.↗
NASA NTRS1982

Cloud height differences on Saturn

Spectrophotometry from 0.6-2.5 micron at 1.5% spectral resolution of Saturn's equator and visibly dark South Equatorial Belt near a 1980 ring-plane crossing shows substantially less absorption by methane over the equator than over the SEB. Model fits using Appleby's model atmosphere and a multiple scattering model lead to the conclusion that the pressure levels of the clouds in the two regions differ by 20%. The region of high clouds is coincident with the location of the equatorial fast jet observed by Voyager.

Apt, J.↗
NASA NTRS1982

Mars: Definition and characterization of global surface units with emphasis on composition

Viking 2 approach maps of red and violet normal albedo are used to define units of similar optical properties for a large area of the Martian surface. Computer processing of these data reveals clusters of albedo values relating to specific, contiguous regions of the planet, with some unit boundaries being of a gradational nature while others are more discrete. A study of the albedo properties of analog materials measured in the laboratory, and of telescopic spectrophotometry of Mars, indicates that both hydroxylated and hematitic oxidized materials exist on the surface. The most probable surface expression of global dust and/or high albedo soils is in the classical bright region, Arabia. Most low albedo features in the region studied have red and violet albedos that are consistent with a dark substrate, such as basalt, coated by, or mixed with, a fine grained alteration product.

Mccord, T. B.↗
NASA NTRS1982

Spectral evidence for the mineralogy of high-albedo soils and dust on Mars

Laboratory spectroscopic observations are presented which further constrain the mineralogy and origin of the high albedo Martian soils and dust, and suggest that nontronite is not a major component of Martian soils, although the presence of other iron-poor clays cannot be excluded on the basis of current observational data. Because the best of the known spectral analogs for the high albedo Martian material is a type of palagonite from Hawaii, it is thought that ferric iron is likely to occur in poorly defined Martian crystallographic sites producing X-ray amorphous weathering products of mafic volcanic glass. These materials form slowly, under semiarid conditions, at ambient temperatures. Since the amorphous Hawaiian soils exist metastably for thousands of years, their Martian analogs may be expected to survive even longer under the present cold and dry climatic conditions.

Singer, R. B.↗
NASA NTRS1982

Visible and near-IR spectral reflectance of geologically important materials: A short review

Examples of reflectance spectra are presented and discussed for various mineral groups including pyroxenes, olivene, phylosilicates, amphiboles, feldspars, oxides and hydroxides, carbonates, and mixtures of minerals. The physical sources of some spectral features are also reviewed such as charge transfer and conduction bands, crystal field absorptions, and vibrational absorptions.

Singer, R. B.↗
NASA NTRS1982

A next-generation mapping spectrometer

Operational and design characteristics for a remote sensing instrument for aircraft and orbital use are defined. The ideal instrument would be based around two-dimensional detector arrays, silicon for the visible and very-near infrared (0.4 to 1.0 microns) and InSb or PbS for the rest of the near-infrared (out to about 2.6 microns). Spectral information would be dispersed along one axis. Thus one exposure or frame would simultaneously record a full spectrum for each pixel in a row perpendicular to the ground track. The instrument should be smart and versatile, with extensive pre-processing capability programmable from the ground. Spatial and spectral resolution, signal to noise radio, data precision, and calibration and atmospheric corrections are also discussed.

Singer, R. B.↗
NASA NTRS1982

Mars - Near-infrared spectral reflectance of surface regions and compositional implications

Both morphological and compositional information are needed to define and characterize surface geologic units on Mars. A description is presented of new, near-infrared spectra (0.65 to 2.50 micrometers) for 11 regions on the Martian surface observed in 1978. The high photometric quality of these data combined with increased near-infrared spectral coverage provide new information about the spectral behavior and, therefore, the composition and physical nature of Martian surface materials. The spectral reflectances were obtained with the aid of a 2.2-m telescope located on Mauna Kea, Hawaii. A cooled (to 77 K) circular variable filter spectrometer with an InSb detector was used to measure alternatively Mars and the standard star Beta Geminorum. Attention is given to general spectral characteristics, the dark region composition, spectral evidence for water, and the 2.3 micrometer absorption.

Mccord, T. B.↗
NASA NTRS1981

Near-infrared spectral reflectance of mineral mixtures - Systematic combinations of pyroxenes, olivine, and iron oxides

Near-infrared spectral reflectance data are presented for systematic variations in weight percent of two component mixtures of ferromagnesium and iron oxide minerals used to study the dark materials on Mars. Olivine spectral features are greatly reduced in contrast by admixture of other phases but remain distinctive even for low olivine contents. Clinopyroxene and orthopyroxene mixtures show resolved pyroxene absorptions near 2 microns. Limonite greatly modifies pyroxene and olivine reflectance, but does not fully eliminate distinctive spectral characteristics. Using only spectral data in the 1 micron region, it is difficult to differentiate orthopyroxene and limonite in a mixture. All composite mineral absorptions were either weaker than or intermediate in strength to the end-member absorptions and have bandwidths greater than or equal to those for the end members. In general, spectral properties in an intimate mixture combine in a complex, nonadditive manner, with features demonstrating a regular but usually nonlinear variation as a function of end-member phase proportions.

Singer, R. B.↗