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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 487 records · Page 27
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NASA NTRS1981

High-resolution passive microwave imaging of the surface of the Earth

The physics of passive microwave observations of the Earth and the system requirements for high-resolution imaging within this spectral band are summarized. High resolution is achieved in a straightforward manner by increasing the size of the primary antenna. However, with a single receiver, it is shown that the combination of high resolution and crosstrack scanning cannot produce images which have valuable geophysical content. The concept of a multiple receiver array located in the focal plane is presented as the only practical solution to the dilemma. Exploring this concept, system requirements are generated which, for the first order, appear to offer solutions to the problem.

Swift, C. T.↗
NASA NTRS1982

Ultra high resolution molecular beam cars spectroscopy with application to planetary atmospheric molecules

The measurement of high resolution pulsed and continuous wave (CW) coherent anti-Stokes Raman spectroscopy (CARS) measurements in pulsed and steady state supersonic expansions were demonstrated. Pulsed molecular beam sources were characterized, and saturation of a Raman transition and, for the first time, the Raman spectrum of a complex molecular cluster were observed. The observation of CW CARS spectra in a molecular expansion and the effects of transit time broadening is described. Supersonic expansion is established as a viable technique for high resolution Raman spectroscopy of cold molecules with resolutions of 100 MH2.

Byer, R. L.↗
NASA NTRS1981

High-resolution radio observations of G82.6+0.4

The region of AFGL 2636, a multicomponent infrared source from which the unidentified 3.3 micron emission feature is observed, has been mapped at 20 cm with a resolution of 1.5 arcsec, at 9 cm at a resolution of 4.6 arcmin, and at 6 cm with a resolution of 0.5 arcsec. It is found that the large-scale distribution of the ionized gas and the extent of the heated dust are well correlated. An upper limit of 3 kpc is placed on the distance to this region. Nine-cm observations of AFGL 437 and AFGL 3053, which also exhibit the 3.3 micron feature, are also discussed.

Rossano, G. S.↗
NASA NTRS1981

High-resolution ultraviolet solar observations from sounding rockets and Spacelab

High spatial (about 1 arcsec) and temporal (20 sec) resolution UV solar spectroscopy has been carried out by the Naval Research Laboratory from sounding rockets since 1975. The High Resolution Telescope and Spectrograph payload, consisting of a 300 mm diameter x 4500 mm focal length Cassegrain telescope and the tandem Woodsworth spectrograph, was used to make the observations. Using this instrument, a multitude of highly energetic phenomena can be observed in the chromosphere, transition zone, and corona. High-resolution photographs of the UV continuum at 1600 A, used to study the fine structure and evolution of the temperature minimum layer, show that because of its strong spatial and temporal intensity fluctuations, the 1600 A continuum emission comes from not only the temperature minimum, but a variety of temperature regimes. Similar spatial and temporal behavior is seen in lower chromospheric lines of Si I. Typical line profiles of the C IV 1550 A line illustrate the fine structure and dynamics of the transition zone; the mass and energy flux balance in this zone is also determined.

Brueckner, G. E.↗
NASA NTRS1982

16 November 1979 gamma-ray bursts observed with HEAO-3 High-Resolution Gamma-Ray Spectrometer

On 1979 November 16, two gamma-ray bursts were observed by the High-Resolution Gamma-Ray Spectrometer on HEAO-3. The first event occurred at 14:16:41 U.T. and lasted about eight seconds. This event was detected only by the instrument's five CsI anticoincidence shield pieces. The second event occurred 61 sec later, at 14:17:42, and lasted about 18 sec. This event was clearly detected by the high-resolution germanium detectors. Because of the close temporal coincidence of the two events, the possibility is considered that both events originated from one celestial source, and that the scanning motion of HEAO-3 (nominal spin period 20 min) excluded the first from the approximately 30 deg FWHM field of view of the germanium detectors but included the second. Directional information from the relative response of the five shield pieces and the earth occultation constraint are all consistent with this interpretation and suggest a source location near RA equals 10 hr, Dec equals 45 deg. No significant spectral features appear in the high-resolution data from the second burst.

Wheaton, W. A.↗
NASA NTRS1982

High-resolution dayglow O I /1304 A/ and O I /989 A/ rocket observations

High-resolution (about 1 A) dayglow observations of the O I(1304) A) and O I(989 A) multiplets were made from an Astrobee-F rocket payload (25.046 CE) launched from White Sands, New Mexico at local noon on June 27, 1980 to an apogee of 260 km. Three components of the O I(1304 A) multiplet were measured at zenith angles of approximately 50 and 140 deg at 1.1 A resolution. Over the entire altitude range of observation, i.e., 100-260 km, the three components were found to be equal to within + or - 15%. The shape of the O I(989 A) multiplet distribution observed on the flight at 1.3 A resolution was indistinguishable from an optically thin source with the energy levels of the excited state populated according to their statistical weights in spite of the large optical depths of the O I(989 A) multiplet at rocket altitudes.

Christensen, A. B.↗
NASA NTRS1982

Assessment of radar resolution requirements for soil moisture estimation from simulated satellite imagery

Radar simulations were performed at five-day intervals over a twenty-day period and used to estimate soil moisture from a generalized algorithm requiring only received power and the mean elevation of a test site near Lawrence, Kansas. The results demonstrate that the soil moisture of about 90% of the 20-m by 20-m pixel elements can be predicted with an accuracy of + or - 20% of field capacity within relatively flat agricultural portions of the test site. Radar resolutions of 93 m by 100 m with 23 looks or coarser gave the best results, largely because of the effects of signal fading. For the distribution of land cover categories, soils, and elevation in the test site, very coarse radar resolutions of 1 km by 1 km and 2.6 km by 3.1 km gave the best results for wet moisture conditions while a finer resolution of 93 m by 100 m was found to yield superior results for dry to moist soil conditions.

Ulaby, F. T.↗
NASA NTRS1982

Spatial and spectral resolution necessary for remotely sensed vegetation studies

An outline is presented of the required spatial and spectral resolution needed for accurate vegetation discrimination and mapping studies as well as for determination of state of health (i.e., detection of stress symptoms) of actively growing vegetation. Good success was achieved in vegetation discrimination and mapping of a heterogeneous forest cover in the ridge and valley portion of the Appalachians using multispectral data acquired with a spatial resolution of 15 m (IFOV). A sensor system delivering 10 to 15 m spatial resolution is needed for both vegetation mapping and detection of stress symptoms. Based on the vegetation discrimination and mapping exercises conducted at the Lost River site, accurate products (vegetation maps) are produced using broad-band spectral data ranging from the .500 to 2.500 micron portion of the spectrum. In order of decreasing utility for vegetation discrimination, the four most valuable TM simulator VNIR bands are: 6 (1.55 to 1.75 microns), 3 (0.63 to 0.69 microns), 5 (1.00 to 1.30 microns) and 4 (0.76 to 0.90 microns).

Rock, B. N.↗
NASA NTRS1984

High resolution GLAS on the MCIDAS

The GLAS physical inversion method for analysis of HIRS2/MSU data was implemented on the McIDAS. The method of analysis is identical to that used in processing global retrievals for six months of 1979, with the exception that the McIDAS retrievals are done on a higher spatial resolution, with one sounding attempted in every 4 x 4 array of HIRS2 spots, corresponding to roughly 80 x 80 km at nadir. This 4 x 4 array is further subdivided in 4 2 x 2 arrays with the sounding being performed utilizing all the spots in the single warmest 2 x 2 quadrant as sensed by the 11 micrometer window channel. Whether accurate retrievals can be performed on the high resolution grid without editing was determined. Different retrievals for a synoptic situation was compared and the guess dependence of the high resolution GLAS retrievals were examined. The orbit crossing the central United States at 1/21/79 09257 was studied. Radiosondes at 1200Z were used for comparison.

Susskind, J.↗
NASA NTRS1984

High resolution observations of low contrast phenomena from an Advanced Geosynchronous Platform (AGP)

Present technology allows radiometric monitoring of the Earth, ocean and atmosphere from a geosynchronous platform with good spatial, spectral and temporal resolution. The proposed system could provide a capability for multispectral remote sensing with a 50 m nadir spatial resolution in the visible bands, 250 m in the 4 micron band and 1 km in the 11 micron thermal infrared band. The diffraction limited telescope has a 1 m aperture, a 10 m focal length (with a shorter focal length in the infrared) and linear and area arrays of detectors. The diffraction limited resolution applies to scenes of any brightness but for a dark low contrast scenes, the good signal to noise ratio of the system contribute to the observation capability. The capabilities of the AGP system are assessed for quantitative observations of ocean scenes. Instrument and ground system configuration are presented and projected sensor capabilities are analyzed.

Maxwell, M. S.↗
NASA NTRS1984

Spatial Resolution Estimation of LANDSAT-4 TM Data

Experiments to determine overall radiometric resolution are discussed. Scene structures, such as roads and field edges, are used with numerical estimation procedures to predict resolution in LANDSAT 4 Thematic Mapper imagery. A nominal resolution of 39 meters is determined rather than the predicted 30 meter prelaunch estimates.

Mcgillem, C. D.↗
NASA NTRS1983

High-resolution infrared spectroscopy of planetary atmospheres

Various techniques for high-resolution infrared spectroscopy of planetary atmospheres are reviewed. Resolving powers of a million are now possible at 1-5 microns with Fourier transform spectrometers and at 10 microns with heterodyne spectrometers. The extension of high-resolution spectroscopy to the far-infrared is currently under development. The role of ground-based high-resolution spectroscopy compared to observations by spacecraft is discussed.

Tokunaga, A. T.↗
NASA NTRS1984

Energy resolution enhancement of mercuric iodide detectors

A pulse processing technique has been developed which improves the gamma-ray energy resolution of mercuric iodide detectors. The technique employs a fast (100 ns) and a slow (6.4 microsec) pulse height analysis to correct for signal variations due to variations in charge trapping. The capabilities of the technique for energy resolution enhancement are discussed as well as the utility of the technique for examining the trapping characteristics of individual detectors. An energy resolution of 2.6 percent FWHM at 662 keV was achieved with an acceptance efficiency of 100 percent from a mercuric iodide detector which gives 8.3 percent FWHM using standard techniques.

Finger, M.↗
NASA NTRS1984

Objective assessment of Advanced Very High Resolution Radiometer data for land cover mapping

The validity of using data from the Advanced Very High Resolution Radiometer (AVHRR) of the satellites NOAA-6 and NOAA-7 for land cover mapping is assessed by making comparisons with much higher resolution LANDSAT multi-spectral scanner (MSS) data. Near synchronous data for both systems are analysed for test sites in the Imperial Valley, California, the Nile Delta, and southern Italy. The results strongly indicate that despite the very coarse resolution of the AVHRR data compared with conventional MSS data they are sufficiently strongly correlated to suggest that the former have significant potential for land cover mapping, especially at small scales and for large areas. Hence the outstanding benefits of AVHRR data, namely their high temporal frequency, relative cheapness and low data volumes for image processing, may readily be taken advantage of for such tasks.

Townshend, J. R. G.↗
NASA NTRS1982

A high-resolution numerical technique for inviscid gas-dynamic problems with weak solutions

The shock resolution of Harten's (1982) second-order explicit method for one-dimensional hyperbolic conservation laws is investigated for a two-dimensional gas-dynamic problem. The possible extension to a high resolution implicit method for both one- and two-dimensional problems is also investigated. Applications of Harten's method to the quasi-one-dimensional nozzle problem with two nozzle shapes (divergent and convergent-divergent) and the two-dimensional shock-reflection problem resulted in high shock resolution steady-state numerical solutions.

Yee, H. C.↗
NASA NTRS1985

Response of Winter Forecasts Made with the GLA Fourth Order GCM to Changes in the Horizontal Grid Resolution

The GLA Fourth Order General Circulation Model was modified in 1984 to allow it to be run at a finer horizontal grid resolution. Previously the standard model versions integrated the primitive equations on a 4 degree latitude by 5 degree longitude grid. Forecasts made at this resolution are compared to others which were made using the finer 2 degree latitude by 2 1/2 degree longitude grid resolution. Three winter cases are included with initial conditions from 15 December 1978, 5 January 1979 and 21 January 1979. The 21 January 1979 initial conditions were taken from a GLAS analysis (experiment 2728) which incorporated the GLAS temperature retrievals. The other two cases used European Center Analysis for initial conditions. The forecasts were all verified against European Center Analysis.

Pfaendtner, J.↗
NASA NTRS1984

Atmospheric effect on spatial resolution of surface imagery

The combined sensor-atmosphere characteristics, defined by the modulation transfer function, are calculated and used to evaluate the apparent resolution of remotely sensed imagery as determined by those characteristics. The atmospheric effect on the upward radiance is described, and the reduction of the apparent spatial resolution due to the atmospheric effect is discussed. The atmospheric effect on remote sensing is compared to the effect of the sensor's pixel size, and results are presented for the maximum resolution that can be achieved in the presence of atmospheric blurring effects.

Kaufman, Y. J.↗
NASA NTRS1985

High-resolution surface photometry of elliptical galaxies

High-resolution CCD surface photometry profiles have been obtained for a sample of 42 nearby elliptical and SO galaxies as a first step in a program to investigate their central structure and core properties. A comparison of the present profiles to those of other observers shows that the accuracy of the central surface brightnesses is to better than 0.02 mag rms. Central resolution is limited by the atmospheric seeing PSF which is measured for each profile. A hybrid Fourier deconvolution procedure has been developed to correct the surface photometry for seeing in a model-independent way. Tests of the procedure on simulated galaxy images show that intrinsic core radii equal to the seeing FWHM or larger can be recovered from the observations. Application of the deconvolution procedure to the observed galaxies yields surface photometry profiles of slightly sub-arc second resolution.

Lauer, T. R.↗