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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

An ERTS multispectral scanner experiment for mapping iron compounds.

An experiment is described which is designed to produce visible-reflective infrared ratio images from ERTS satellite data. The ERTS-A multispectral scanner has two channels in the visible-reflective infrared wavelength region which should be capable of duplicating aircraft scanner results. The average reflectances in the four ERTS-A MSS spectral bands for a few minerals and some vegetation are tabulated. The mineral laboratory samples were granular, with a particle diameter range of 250 to 1200 micrometer. If there were no spectral atmospheric or illumination variation effects, the ratio of energies in band 1 to band 4 would permit discrimination of pyroxenes (found in basic and ultrabasic rocks), quartz (found in acidic rocks), limonite and hematite (iron oxides), and green vegetation, on the basis of their respective ratio magnitudes.

Vincent, R. K.↗
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

CO2 laser waveguiding in proton implanted GaAs

Surface layers capable of supporting optical modes at 10.6 microns have been produced in n-type GaAs wafers through 300 keV proton implantation. The dominant mechanism for this effect appears to be free carrier compensation. Characterization of the implanted layers by analysis of infrared reflectivity spectra and synchronous coupling at 10.6 microns produced results in good agreement with elementary models. These results of sample characterization by infrared reflectivity and by CO2 laser waveguiding as implanted are presented and evaluated.

Jenkinson, H. A.↗
NASA NTRS1972

An ERTS multispectral scanner experiment for mapping iron compounds

There are no author-identified significant results in this report. An experimental plan for enhancing spectral features related to the chemical composition of geological targets in ERTS multispectral scanner data is described. The experiment is designed to produce visible-reflective infrared ratio images from ERTS-1 data. Iron compounds are promising remote sensing targets because they display prominent spectral features in the visible-reflective infrared wavelength region and are geologically significant. The region selected for this ERTS experiment is the southern end of the Wind River Range in Wyoming. If this method proves successful it should prove useful for regional geologic mapping, mineralogical exploration, and soil mapping. It may also be helpful to ERTS users in scientific disciplines other than geology, especially to those concerned with targets composed of mixtures of live vegetation and soil or rock.

Vincent, R. K.↗
NASA NTRS1990

Implementation of Sensor and Control Designs for Bioregenerative Systems

The goal of the Spring 1990 EGM 4001 Design class was to design, fabricate, and test sensors and control systems for a closed loop life support system (CLLSS). The designs investigated were to contribute to the development of NASA's Controlled Ecological Life Support System (CELSS) at Kennedy Space Center (KSC). Designs included a seed moisture content sensor, a porous medium wetness sensor, a plant health sensor, and a neural network control system. The seed group focused on the design and implementation of a sensor that could detect the moisture content of a seed batch. The porous medium wetness group concentrated on the development of a sensor to monitor the amount of nutrient solution within a porous plate incorporating either infrared reflectance or thermal conductance properties. The plant health group examined the possibility of remotely monitoring the health of the plants within the Biomass Production Chamber (BPC) using infrared reflectance properties. Finally, the neural network group concentrated on the ability to use parallel processing in order to control a robot arm and analyze the data from the health sensor to detect regions of a plant.

Rodriguez, Pedro R.↗
NASA NTRS1981

Moon - Near-infrared spectral reflectance, a first good look

Spectral reflectance contains direct information on the mineralogy of the surface soils and rocks. A problem concerning the employment of remote spectral-reflectance sensing techniques for mineralogical studies is related to the lack of photometrically precise spectra of planetary surfaces in the region from 1.0 to 2.5 micrometers, where additional important mineral absorptions occur. Recently, a new instrument was developed, and an observational program is underway to provide the required near-infrared spectra. The first, comprehensive near-infrared spectroscopic results for the moon are presented. It is shown that it is equally possible to derive quantitative mineralogical information about the lunar surface by using remotely sensed reflectance spectra as it is by using laboratory reflectance measurements of lunar samples.

Mccord, T. B.↗
NASA NTRS1993

Study of atmospheric and bidirectional effects on surface reflectance and vegetation index time series: Application to NOAA AVHRR and preparation for future space missions

The objectives of the investigation, namely 'to characterize the atmospheric and directional effects on surface reflectance and vegetation index using the First International Satellite Cloud Climatology Project (ISLCSP) Field Experiment (FIFE) data set, develop new algorithms to obtain better Advanced Very High Resolution Radiometer (AVHRR) indices, and define possible improvements for future satellite missions', were addressed in three separate, yet complementary studies. First, it was shown, from theoretical calculations, that visible and near infrared reflectances combined linearly at optimum (one or two) viewing angles relate linearly to the fraction of photosynthetically available radiation absorbed by plants, f(sub par), can be used independently of the type of foliage and substrate, eliminate the effects of sub-pixel spatial heterogeneity, and improve the accuracy of the f(sub par) estimates when compared to the Normalized Difference Vegetation Index, NDVI. Second, it was demonstrated that NDVI, even though it is not a linear combination of radiances or reflectances, can be spatially integrated without significant loss of information from scales of 300 to 1000 m. Third, AVHRR visible and near-infrared reflectances over the FIFE site, separating temporal and bidirectional components and determining the model parameters through an original iterative scheme was successfully modeled. It appears that NDVI generated from the top-of-atmosphere reflectances normalized by the bidirectional effects (as determined in the scheme) is a better vegetation index than maximum NDVI. Details about the three studies are presented.

Frouin, Robert↗
NASA NTRS1979

Infrared analysis of polyethylene wear specimens using attenuated total reflection spectroscopy

Attenuated total reflection infrared spectroscopy was used to analyze ultrahigh molecular weight polyethylene wear test specimens. Three different specimens were analyzed. One specimen was gamma irradiated to a dose of 5.0 MRad, another to a dose of 2.5 MRad, and the final specimen was unirradiated. There was no conclusive evidence of chemical changes (i.e., unsaturation or oxidation) in the surface regions of any of the polyethylene samples. Therefore, it was concluded that the gamma irradiation sterilization procedure shoud not alter the boundary lubricating properties of the polyethylene.

Jones, W. R.↗
NASA NTRS1974

Refinement in black chrome for use as a solar selective coating

Black chrome is significant as a solar selective coating because the current extensive use of black chrome in the electroplating industry as a durable decorative finish makes black chrome widely available on a commercial scale and potentially low in cost as a solar selective coating. Black-chrome deposits were modified by underplating with dull nickel or by being plated on rough surfaces. Both of these procedures increased the visible absorptance. There was no change in the infrared reflectance for the dull-nickel - black-chrome combination from that reported for the bright-nickel - black-chrome combination. However, the bright-nickel - black-chrome coating plated on rough surfaces indicated a slight decrease in infrared reflectance. As integrated over the solar spectrum for air mass 2, the reflectance of the dull-nickel - black-chrome coating was 0.077, of the bright-nickel - black-chrome coating plated on a 0.75-micron (30-microinch) surface was 0.070, of the bright-nickel - black-chrome coating plated on a 2.5 micron (100-microinch) surface was 0.064. The corresponding values for the bright-nickel - black-chrome coating on a 0.0125-micron (0.5-microinch) surface, two samples of black nickel, and two samples of Nextrel black paint were 0.132, 0.123, 0.133, and 0.033, respectively.

Mcdonald, G. E.↗
NASA NTRS1972

Ultraviolet radiation effects on the infrared damage rate of a thermal control coating

The effects of ultraviolet radiation on the infrared reflectance of ZnO silicone white thermal coatings were investigated. Narrow band ultraviolet radiation for wavelengths in the 2200A to 3500A range by a monochromator and a high pressure, 150-W Eimac xenon lamp. The sample was irradiated while in a vacuum of at least 0.000001 torr, and infrared reflectance was measured in situ with a spectroreflectometer at 19,500A. Reflectance degradation was studied as a function of wavelength, time, intensity, and dose. Damage was wavelength dependent at constant exposure, but no maximum was evident above the shortest wavelength investigated here. The degradation rate at constant intensity was an exponential function of time and varies with intensity.

Bass, J. A.↗
NASA NTRS2006

Infrared Instrument for Detecting Hydrogen Fires

The figure shows an instrument incorporating an infrared camera for detecting small hydrogen fires. The instrument has been developed as an improved replacement for prior infrared and ultraviolet instruments used to detect hydrogen fires. The need for this or any such instrument arises because hydrogen fires (e.g., those associated with leaks from tanks, valves, and ducts) pose a great danger, yet they emit so little visible light that they are mostly undetectable by the unaided human eye. The main performance advantage offered by the present instrument over prior hydrogen-fire-detecting instruments lies in its greater ability to avoid false alarms by discriminating against reflected infrared light, including that originating in (1) the Sun, (2) welding torches, and (3) deliberately ignited hydrogen flames (e.g., ullage-burn-off flames) that are nearby but outside the field of view intended to be monitored by the instrument. Like prior such instruments, this instrument is based mostly on the principle of detecting infrared emission above a threshold level. However, in addition, this instrument utilizes information on the spatial distribution of infrared light from a source that it detects. Because the combination of spatial and threshold information about a flame tends to constitute a unique signature that differs from that of reflected infrared light originating in a source not in the field of view, the incidence of false alarms is reduced substantially below that of related prior threshold- based instruments.

Youngquist, Robert↗
NASA NTRS1978

Mars - Near-infrared spectral reflectance and compositional implication

Several distinct absorption features, some recognized for the first time, are evident in a newly obtained reflectance spectrum (wavelengths = 0.62-2.6 microns, reciprocal dispersion = 83) of the integral disk of Mars. The effects of Martian atmospheric CO2 have been removed from the spectrum to arrive at a reflectance spectrum that is believed to be due mostly to surface material. Absorptions, at 1.22, 1.55, and 2.05 microns are interpreted to indicate the presence of H2O ice plus high desiccated mineral hydrate, although an H2O ice phase with strongly shifted fundamental frequencies cannot be ruled out. Ferrosilicate and ferric oxide bands near and shortward of 1.0 micron are confirmed. The new observations were made on April 21-23, 1976, universal time, at the 2.24-m telescope on Mauna Kea, Hawaii, using a newly developed infrared spectrometer.

Mccord, T. B.↗
NASA NTRS1970

Linear geologic structure and magic rock discrimination as determined from infrared data

Color infrared photographs of the Beartooth Mountains, Montana show the distribution of mafic dikes and amphibolite bodies. Lineaments that cross grassy plateaus can be identified as dikes by the marked constrast between the dark rocks and the red vegetation. Some amphibolite bodies in granitic terrain can also be detected by infrared photography and their contacts can be accurately drawn due to enchanced contrast of the two types of rock in the near infrared. Reflectance measurements made in the field for amphibolite and granite show that the granite is 25% to 50% more reflective in the near infrared than in the visible region. Further enhancement is due to less atmospheric scattering than in the visible region. Thermal infrared images of the Mill Creek, Oklahoma test site provided information on geologic faults and fracture systems not obtainable from photographs. Subtle stripes that cross outcrop and intervening soil areas and which probably record water distribution are also shown on infrared photographs.

Offield, T. W.↗
NASA NTRS1978

Plagioclase feldspars - Visible and near infrared diffuse reflectance spectra as applied to remote sensing

Visible and near IR diffuse reflectance spectra of plagioclase feldspars are characterized by absorption features caused by minor amounts of Fe(2+) that occur bound in the crystal structure. It is found that identification of terrestrial feldspars by remote sensing appears to be feasible for the compositional range An50 to An80, providing that other minerals do not mask the feldspar signatures. Determination of plagioclase composition using the wavelength of the Fe(2+) band may be possible for lunar samples, where the plagioclase can be assumed to be more calcic than An65.

Adams, J. B.↗