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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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Complementarity of UV and IR differential absorption lidar for global measurements of atmospheric species

An analysis of the potential capabilities of a spectrally diversified DIAL technique for monitoring atmospheric species is presented assuming operation from an earth-orbiting platform. Emphasis is given to the measurement accuracies and spatial and temporal resolutions required to meet present atmospheric science objectives. The discussion points out advantages of spectral diversity to perform comprehensive studies of the atmosphere; in general it is shown that IR systems have an advantage in lower atmospheric measurements, while UV systems are superior for middle and upper atmospheric measurements.

Megie, G.↗
NASA NTRS1980

Far-infrared spectra of W51-IRS 2 and W49 NW

Measurements of the far-infrared spectra of the powerful H II regions W51-IRS 2 and W49 NW from 65 to 345 per cm with about 9 per cm resolution were obtained by using an airborne Michelson interferometer. The most remarkable feature of the far-infrared spectra of the two regions is the smoothness of the continuum; no evidence is found in the spectra for features of H2O ice at 45 and 62 microns. The spectrum of W51 is well fitted by a 70 K blackbody with a diameter of 14 arc sec, but the spectrum of W49 NW is narrower than a blackbody. The implications of the apparently high peak optical depths of these sources are discussed.

Erickson, E. F.↗
NASA NTRS1980

IR observations of the double quasar 0957 + 561 A, B and the intervening galaxy

Infrared observations of the double quasar 0957 + 561 A, B and the intervening galaxy believed to be responsible for its double appearance by gravitational light deflection are reported. Observations were obtained of each quasar at 1.6 and 2.2 microns and of the 12.5 arcsec region centered between the two quasars at 1.2, 1.6 and 2.2 microns. Extended IR emission is observed in the vicinity of both quasars and is attributed to emission from the intervening galaxy. The two quasars are found to have a constant flux ratio in all observed wavelength ranges, consistent with the achromatic imaging predicted by the gravitational lens model, and to exhibit an unusual continuum distribution in the region 0.35-2.2 microns. The infrared observations are also consistent with a giant elliptical lens galaxy at a redshift of approximately 0.40.

Soifer, B. T.↗
NASA NTRS1981

Stratospheric trace constituent profile retrievals using laser heterodyne radiometer IR limb sensing spectra

A retrieval technique for high resolution IR solar occultation limb sensing data is described for profiling stratospheric trace constituents. Remote measurement of ClO during sunset in the 24-45-km region with a 2-km height resolution is chosen as an example. Two types of instruments are considered: a laser heterodyne radiometer with line resolving spectral resolution and an interferometer spectrometer with a fixed slit width of 0.02/cm. It is pointed out that a multichannel approach is necessary with the heterodyne instrument for improved retrieval accuracy. The error analysis indicates the relative sizes of instrument noise and other sources of error in the retrieval of altitude profiles with high (2-km) vertical resolution.

Majumdar, A. K.↗
NASA NTRS1982

Determination of sea surface temperatures from microwave and IR data

Microwave measurements from the Nimbus 7 SMMR were used to derive the atmospheric precipitable water, which was then used to obtain the atmospheric correction for use with AVHRR thermal IR measurements to obtain sea surface temperature (SST). The resulting SST's were compared with the NOAA operational sea surface temperature measurements, and the two sets of measurements were found to be in reasonable agreement. The average residuals between the two sets of measurements was 0.15 K with the NOAA operational SST's being slightly greater.

Rangaswamy, S.↗
NASA NTRS1982

Organic and inorganic interpretations of the Martian UV-IR reflectance spectrum

Viking Lander biology experiment gas chromatography-mass spectrometer analysis has detected no organic molecules above a concentration of parts per billion. The questions considered here include the reason for the lack of organic molecules at the landing sites, whether the sterility of the two sites is representative of the whole of Mars, and whether there may be locations more conducive to organic compound formation and preservation. After simulating the destruction of organic compounds in Mars-like laboratory conditions and examining whether the destructive mechanism might obtain throughout the planet, UV and IR reflectance spectra are re-examined for any evidence of organic molecules and an upper limit is determined for organic carbon content of average Martian soil. It is found that the average Martian soil is poor in inorganics, presents a poor habitat for carbon chemistry-based life forms, and is not likely to preferentially preserve such organisms anywhere on the planet.

Pang, K. D.↗
NASA NTRS1982

Parameterization of IR cooling in a middle atmosphere dynamics model. I - Effects on the zonally averaged circulation

A computationally efficient two-stream parameterization of IR cooling is developed for a middle atmosphere dynamics model. The parameterization combines the monochromatic feature of an emissivity formulation with the computational simplicity of a single spatial integral to evaluate the monochromatic transfer equation. Calculations show strong radiative control of the mesopause region and the need for substantial deceleration of the mean zonal winds. Calculated temperatures show good agreement in the summer hemisphere where planetary wave activity is negligible, but in the polar night of the winter hemisphere they are about 30 K too cold, which suggests planetary wave heating must make up the deficit. With observed ozone densities, globally averaged radiative equilibrium temperatures in the 65-75 km region are too cold and an additional heat source about 1 K/day is required.

Apruzese, J. P.↗
NASA NTRS1981

A combined visible and IR technique for the estimation of rainfall amounts from GOES data

The use of visible and infrared techniques for estimating precipitation for flash flood, hydrological, and agricultural applications is discussed. Satellite derived rainfall estimates supplement other data or are the only data available. The Scofield/Oliver convective rainfall technique is used for analyzing a half hour period of heavy rainfall during a Chicago flash flood event. The results of a real time hydrological application of the Scofield/Oliver technique for the Hurricane Allen event are also presented. Visible and IR techniques for agricultural applications are also discussed.

Austin, G. L.↗
NASA NTRS1983

Communications and tracking - Light and IR will help carry high traffic

The space station currently under consideration by NASA must simultaneously track and communicate with the many vehicles and objects surrounding it in orbit. While the Space Shuttle has 23 antennas, more than 50 will be required by the space station. In addition to Shuttle-compatible equipment at P, L, C, S, and Ku bands, the station system will probably incorporate Ka, W, IR and optical frequency equipment for tracking and communications. A major design challenge is foreseen in the placement of separate antennas, lenses and reflectors over the station's external geometry in order to give both the overlapping fields of view required for spherical coverage and the radiation of unambiguous navigation guide beams and markers. Adaptive distributed element arrays are under consideration. Another approach to spherical coverage involves the use of omnidirectional antennas which both transmit and receive RF energy over a wide range of angles.

Dickinson, R. M.↗
NASA NTRS1984

Integrating IR detector imaging systems

An integrating IR detector array for imaging is provided in a hybrid circuit with InSb mesa diodes in a linear array, a single J-FET preamplifier for readout, and a silicon integrated circuit multiplexer. Thin film conductors in a fan out pattern deposited on an Al2O3 substrate connect the diodes to the multiplexer, and thick film conductors also connect the reset switch and preamplifier to the multiplexer. Two phase clock pulses are applied with a logic return signal to the multiplexer through triax comprised of three thin film conductors deposited between layers. A lens focuses a scanned image onto the diode array for horizontal read out while a scanning mirror provides vertical scan.

Bailey, G. C.↗
NASA NTRS1984

Requirements for a passive IR advanced moisture and temperature sounder

The design of a high spectral resolution, lambda/delta lambda being approximately 1200 IR, sounder capable of increasing the vertical resolution of atmospheric temperature profiles and achieving a rms accuracy of approximately 1.5 K is discussed. This sounder permits improved determination of meteorological parameters on cloudiness, surface temperature, and air-surface interactions. A set of channels from the high J lines in the R branch of the 4.3-micron CO2 band complemented by a larger set of window, humidity, and temperature channels in the 3.7-, 6.3-, 9-, and 15-micron regions is used. Design and simulation studies show that such a sounder is within the present state of the art.

Chahine, M. T.↗
NASA NTRS1983

Developments with multispectral thermal-IR and active microwave systems - TIMS, SIR-A, SIR-B, and radarsat

An update of current and future systems for spectral scanning of geological features in the thermal-IR, and active microwave bands is presented. The design characteristics of four individual systems are described, including the NASA Thermal Infrared Multispectral Scanner (TIMS); the Shuttle Imaging Radars A and B (SIRA-A and SIRA-B); and the Canadian RADARSAT satellite for geological mapping and ice monitoring. The applications of spectral data from the Side Looking Airborne Radar (SLAR), the GEMS 100 mapping system, and the Landsat RBV instrument to the mapping of large geological structures are also described.

Harrison, P. G.↗
NASA NTRS1985

Physics and design of advanced IR bolometers and photoconductors

The state-of-the-art in photoconductors and bolometers is reviewed, centering on the materials development and concepts of extrinsic Si and Ge devices. It is suggested that in the field of 2-D detector arrays the hybrid circuits containing a photoconductor or a photodiode array, bonded with In solder to a switched MOS readout device with up to 60 x 60 elements, will produce superior performance. Other systems discussed include charge-coupled devices, developed for visible-light imaging and adapted to IR imaging, and charge-injection devices, a monolithic combination of a standard photoconductor and a metal-insulator-semiconductor capacitor. Finally, it is pointed out that a nonequilibrium theory of bolometer noise demonstrates the possibility of reducing the traditionally accepted noise limits by 60 percent for Johnson noise and 30 percent for the noise from phonons in the thermal link of the bolometer.

Haller, E. E.↗
NASA NTRS1983

Broadband transmission functions for atmospheric IR flux computations and climate studies

In order to reduce the size of precomputed tables which are used in the emissivity approach to computing IR radiation in a climate model, the three-dimensional transmission function in the water vapor bands is defined in this study by a simple regression equation consisting of three two-dimensional parameters. The transmittances in the 9.6 and 15 micron bands are individually parameterized as functions of the amount of scaled absorber. This approach can thus be applied to atmospheres with a variable CO2 concentration.

Chou, M.-D.↗
NASA NTRS1985

A cool anomaly off northern California - An investigation using IR imagery and in situ data

The OPTOMA (Ocean Prediction Through Observation, Modeling and Analysis) program is developing an ocean descriptive-predictive system for four-dimensional data assimilation. It is presently concerned with the mesoscale variability in the California Current System (CCS). The present paper has the objective to assess the relationship of surface temperature structure to subsurface temperature structure and flow fields. Surface temperature anomalies are related to the mesoscale horizontal advective and subsurface mass fields. The cool anomaly off northern California in summer 1982 is discussed, taking into account the temperature structure along transects, T-S variations and inferred water masses, variation of horizontal temperature patterns with depth, and synoptic information from IR data.

Rienecker, M. M.↗