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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 NTRS2003

InGaAsSb Detectors' Characterization for 2-Micron CO2 Lidar/DIAL Applications

Recent interest in monitoring atmospheric CO2 focuses attention on infrared remote sensing using the 2-micron lidar/differential absorption lidar (DIAL) technique. Quantum detectors are critical components in this technique, and many research efforts concentrate on developing such devices for the 2-micron wavelength. Characterization results of InGaAsSb quantum detectors for the 2-micron wavelength range are presented, including experimental setup and procedure. Detectors are prototype devices manufactured by using separate absorption and multiplication (SAM) structures. Characterization experiments include V-I measurements, spectral response and its variation with bias voltage and temperature, noise measurements, noise-equivalent-power (NEP) and detectivity calculations, and signal-to-noise ratio (SNR) estimation. A slight increase in the output signal occurred with increased bias voltage and was associated with a noise level increase. Cooling down the detectors reduces noise and shifts the cutoff wavelength to shorter values. Further improvement in the design and manufacturing process, by increasing the device gain and lowering its noise level, is necessary to meet the required CO2 lidar/DIAL specifications.

Refaat, Tamer F.↗
NASA NTRS2003

InGaAsSb Detectors Characterization for 2-Micron CO2 Lidar/DIAL Applications

Recent interest in monitoring atmospheric CO2 focuses attention on infrared remote sensing using the 2-micron lidar/differential absorption lidar (DIAL) technique. Quantum detectors are critical components in this technique, and many research efforts concentrate on developing such devices for the 2-micron wavelength. Characterization results of InGaAsSb quantum detectors for the 2-micron wavelength range are presented, including experimental setup and procedure. Detectors are prototype devices manufactured by using separate absorption and multiplication (SAM) structures. Characterization experiments include V-I measurements, spectral response and its variation with bias voltage and temperature, noise measurements, noise-equivalent-power (NEP) and detectivity calculations, and signal-to-noise ratio (SNR) estimation. A slight increase in the output signal occurred with increased bias voltage and was associated with a noise level increase. Cooling down the detectors reduces noise and shifts the cutoff wavelength to shorter values. Further improvement in the design and manufacturing process, by increasing the device gain and lowering its noise level, is necessary to meet the required CO2 lidar/DIAL specifications.

Refaat, Tamer F.↗
NASA NTRS2015

Exploring the Cloud Icy Early Mars Hypothesis Through Geochemistry and Mineralogy

While ancient fluvial channels have long been considered strong evidence for early surface water on Mars, many aspects of the fluvial morphology and occurrence suggest that they formed in relatively water limited conditions (com-pared to Earth) and that climatic excursions allowing for surface water might have been short-lived. Updated results mapping valley networks at higher resolution have changed this paradigm, showing that channels are much more abundant and wide-spread, and of higher order than was previously recognized, suggesting that Mars had a dense enough atmosphere and warm enough climate to allow channel formation up to 3.6-3.8 Ga. This revised view of the ancient martian climate might be broadly consistent with a climate history of Mars devised from infrared remote sensing of surface minerals, suggesting that widespread clay minerals formed in the Noachian, giving way to a sulfur-dominated surface weathering system by approx. 3.7 Ga.

Niles, P. B.↗
NASA NTRSDate not supplied

Global Land Surface Soil Moisture Database Derived from IASI Measurements on Board MetOp Satellites

Global land surface soil moisture has been derived from MetOp IASI ultraspectral infrared measurements over the past 16 years. Monthly and spatially gridded soil moisture is produced to show some phenomena associated with its natural variability. This study has aimed to demonstrate that thermal infrared remote sensing data can be used for monitoring global surface environmental characteristics and associated change through the continuity observations provided by the MetOp series. The time-series of soil moisture can be used to estimate its associated trend.

Remote sensing↗
NASA NTRS1976

Remote sensing of atmospheric pollutant gases using an infrared heterodyne spectrometer

Remote sensing of the concentration and vertical distribution of atmospheric gases using an infrared heterodyne spectrometer (IHS) has been investigated, and a dual (C-13)(O-16)2 laser multichannel IHS has been developed. Analyses of nadir thermal-radiance measurements from an aircraft at 10-km altitude and of solar absorption measurements from the ground indicate that initial applications of the IHS to tropospheric measurements of NH3 and O3 are feasible with measurement precisions ranging from 0.5 to 2 ppb and 20 to 30 ppb, respectively. These analyses have included effects of potential retrieval-error sources and have resulted in specifications of measurement modes, optimum signature lines, required system parameters, and expected sensitivities. Preliminary instrument performance data are presented.

Seals, R. K., Jr.↗
NASA NTRS1988

The basis for the spectral behaviour of silicates in the thermal infrared and applications to remote sensing

Variations in the thermal infrared (TIR) spectral response of silicate rocks is related to changes in the structures and divalent cation contents of the minerals which form the rocks. These considerations lead to a chemical parameter, SCFM, which reflects mineral structures, rock types, and their spectra. The parameter is the ratio of silica to the abundance of depolymerizing cations, defined as SCFM = SiO2/SiO2 + CaO + MgO + FeO. Parameter SCFM is therefore proposed for use in TIR remote sensing of igneous rocks. It is also demonstrated that two or three broad bands are sufficient for distinguishing among major rock types and the system noise has little effect on the quality of the results. These factors can be traded off against improved spatial resolution in instrument design.

Walter, L. S.↗
NASA NTRS1986

The physical basis for spectral variations in thermal infrared emittance of silicates and application to remote sensing

The use of infrared spectroscopy for the remote characterization of planetary surfaces has received attention due to efforts in the investigation of these bodies from space. In the 8 to 14 micron region, a depression in the emittance spectra of rocks (sometimes called reststrahlen) is related to the fundamental stretching vibrations of Si-O bonds and shifts in the locations of this feature are ascribed to variations in rock composition. Thus, it should be possible to investigate, quantify, and model the relationships of reststrahlen spectral band location through silicate mineralogical composition to rock classification. This concept will be tested first through the use of laboratory-acquired data on the infrared spectra and mineralogy of selected mineral and rock samples. As a suitable classification model is developed, it will be tested through overflights of appropriate rock outcrops using the Thermal Infrared Multispectral Scanner (TIMS).

Walter, Louis S.↗
NASA NTRS1972

The use of Kodak aerochrome infrared color film, type 2443, as a remote sensing tool

An infrared color film, Kodak Aerochrome, type 2443, has replaced the 8443 film. The 2443 has lower contrast than the 8443 film, and allows deeper probing into areas that appear as solid black shadows on the 8443 film. The cyan layer of 2443 is approximately 1 1/2 stops slower, at a density of 1.4, than the yellow and magenta emulsion layers.

Cooper, G. R.↗
NASA NTRS1976

Infrared multidetector spectrometer for remote sensing of temperature profiles in the presence of clouds

An infrared multidetector spectrometer with channels in the 4.3-micron and 15-micron CO2 bands for the remote sensing of temperature profiles in the presence of clouds is described. Results obtained from aircraft flights in July 1975 over ocean sites under various conditions of cloudiness demonstrate the capability of the dual frequency technique to recover surface temperatures to an accuracy of + or - 0.5 K in the presence of up to 90% cloud cover.

Aumann, H. H.↗
NASA NTRS1984

Titan - Far-infrared and microwave remote sensing of methane clouds and organic haze

Titan's surface and plausible atmospheric thermal opacity sources, which include gaseous N2, CH4, and H2, together with CH4 clouds and organic haze, are sufficient to match available earth-based and Voyager observations of Titan's thermal emission spectrum. Dominant thermal emission sources are the surface, at greater than 1 cm wavelengths, atmospheric N2 for the 1-200 micron range, condensed and gaseous CH4 for 200-20 microns, and molecular bands and organic haze at less than 20 microns.

Thompson, W. R.↗
NASA NTRS1986

Discrimination of soil hydraulic properties by combined thermal infrared and microwave remote sensing

Using the De Vries models for thermal conductivity and heat capacity, thermal inertia was determined as a function of soil moisture for 12 classes of soil types ranging from sand to clay. A coupled heat and moisture balance model was used to describe the thermal behavior of the top soil, while microwave remote sensing was used to estimate the soil moisture content of the same top soil. Soil hydraulic parameters are found to be very highly correlated with the combination of soil moisture content and thermal inertia at the same moisture content. Therefore, a remotely sensed estimate of the thermal behavior of the soil from diurnal soil temperature observations and an independent remotely sensed estimate of soil moisture content gives the possibility of estimating soil hydraulic properties by remote sensing.

Vandegriend, A. A.↗
NASA NTRS1994

Mid-infrared spectropolarimetry as a remote sensing tool

A preliminary investigation of mid-infrared spectropolarimetry as a new technique to accurately measure features in the thermal spectra of planetary regoliths is described. The 5- to 12-micron polarization of igneous rocks and powders commonly found on planetary surfaces is measured to explore the viability of this technique for future groundbased and space-based experiments. Mid-infrared polarization is found to be diagnostic of composition for both whole rock and sand samples, while exhibiting less interference from surface roughness effects than with mid-infrared spectrophotometry.

Johnson, Paul E.↗
NASA NTRS1984

On the remote sensing of cloud properties from satellite infrared sounder data

A method for remote sensing of cloud parameters by using infrared sounder data has been developed on the basis of the parameterized infrared transfer equation applicable to cloudy atmospheres. The method is utilized for the retrieval of the cloud height, amount, and emissivity in 11 micro m region. Numerical analyses and retrieval experiments have been carried out by utilizing the synthetic sounder data for the theoretical study. The sensitivity of the numerical procedures to the measurement and instrument errors are also examined. The retrieved results are physically discussed and numerically compared with the model atmospheres. Comparisons reveal that the recovered cloud parameters agree reasonably well with the pre-assumed values. However, for cases when relatively thin clouds and/or small cloud fractional cover within a field of view are present, the recovered cloud parameters show considerable fluctuations. Experiments on the proposed algorithm are carried out utilizing High Resolution Infrared Sounder (HIRS/2) data of NOAA 6 and TIROS-N. Results of experiments show reasonably good comparisons with the surface reports and GOES satellite images.

Yeh, H. Y. M.↗
NASA NTRS1981

International Geoscience and Remote Sensing Symposium, Washington, DC, June 8-10, 1981, Digest. Volumes 1 & 2

Sensors used for the geophysical and remote sensing studies are reviewed; in particular, NIMBUS-7 Scanning Multichannel Microwave Radiometer results are given. Remote sensing analyses consider such areas as hydrology, soil moisture, and planetary surfaces. In addition, Shuttle remote sensing experiments and SAR systems, remote sensing in the thermal infrared, and microwave remote sensing of the earth are considered. Finally, attention is given to lithologic and geobotanical studies, and geophysical sensing techniques and inversion theory.

Source record↗
NASA NTRS1989

Effect of metal stress on the thermal infrared emission of soybeans: A greenhouse experiment - Possible utility in remote sensing

Manganese-sensitive forest and manganese-tolerant lee soybean cultivars were subjected to differential manganese stress in loring soil in a greenhouse experiment. Leaf temperature measurements were made using thermistors for forest and lee. Manganese-stressed plants had higher leaf temperatures than control plants in both forest and lee. Results of this experiment have potential applications in metal stress detection using remote sensing thermal infrared data over large areas of vegetation. This technique can be useful in reconnaissance mineral exploration in densely-vegetated regions where conventional ground-based methods are of little help.

Suresh, R.↗
NASA NTRS2021

Stokes resolved differential temperature: an important metric of polarimetric precision in the long-wave infrared

In remote sensing, radiometric measurements taken in the mid-wave infrared and beyond (λ >3μm) are commonly reported in units of Kelvin by utilizing Planck’s radiation law to relate measured radiance and target brightness temperature (Tb). Thus, it is desirable to match this formalism in thermal polarimetry and report the unnormalized Stokes parameters in units of K instead of radiance (Wm−2sr−1). This approach also al-lows common performance metrics in long-wave infrared (LWIR) imaging such as Noise Equivalent DifferentialTemperature (NEDT) to be modified and extended to metrics of polarimetric accuracy and precision. However, since the relationship between measured radiance and Tb are non-linear, the conversion of I, Q, and U in units of radiance to Tb,Tb,Q, and Tb,U in K is ambiguous. As a solution a metric of performance for thermal linear Stokes polarimetry, the Stokes resolved differential temperature (SRDT), is introduced.

polarimetry↗