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At least 1,693 records · Page 94
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Analysis of a multisensor image data set of south San Rafael Swell, Utah

A Shuttle Imaging Radar (SIR-A) image of the southern portion of the San Rafael Swell in Utah has been digitized and registered to coregistered Landsat, Seasat, and HCMM thermal inertia images. The addition of the SIR-A image to the registered data set improves rock type discrimination in both qualitative and quantitative analyses. Sedimentary units can be separated in a combined SIR-A/Seasat image that cannot be seen in either image alone. Discriminant Analyses show that the classification accuracy is improved with addition of the SIR-A image to Landsat images. Classification accuracy is further improved when texture information from the Seasat and SIR-A images is included.

Evans, D. L.↗
NASA NTRS1984

Mesoscale analysis of 6.7 micron image data from the VISSR Atmospheric Sounder (VAS) for several case studies

Several case studies are examined in an attempt to relate Visible infrared spin scan radiometers Atmospheric Sounder (VAS) water vapor channel radiance data to atmospheric moisture. Since the 6.7 micrometer channel detects radiation emitted by atmospheric water vapor from a rather thick layer, a scheme is developed which weighted rawinsonde observations of relative humidity in a similar manner. A comparison of the two fields (weighted relative humidity values from gridded rawinsonde observations and the VAS water vapor image) indicates that even when mesoscale data are used, the technique only presented a smooth representation of the radiance field. This weighting function is dependent on both the temperature and moisture distribution of the atmosphere. Cross sections of relative humidity from the mesoscale rawinsondes are produced which sliced the water vapor imagery in particularly interesting regions (areas of high and low blackbody temperatures). Comparisons are then made between the cross sections and the variations in the VAS radiance data along the cross section line. Bright regions in the water vapor imagery (cold blackbody temperatures) are often associated with thin layers of high relative humidity or thick layers of only moderately moist air. The reverse also applies, i.e., dark regions (warm blackbody temperatures) in the imagery corresponded well with very dry regions in the cross sections.

Jedlovec, G. J.↗
NASA NTRS1987

Interpreting forest and grassland biome productivity utilizing nested scales of image resolution and biogeographical analysis

This report summarizes progress made in our investigation of forest productivity assessment using TM and other biogeographical data during the third six-month period of the grant. Data acquisition and methodology hurdles are largely complete. Four study areas for which the appropriate TM and ancillary data were available are currently being intensively analyzed. Significant relationships have been found on a site by site basis to suggest that forest productivity can be qualitatively assessed using TM band values and site characteristics. Perhaps the most promising results relate TM unsupervised classes to forest productivity, with enhancement from elevation data. During the final phases of the research, multi-temporal and regional comparisons of results will be addressed, as well as the predictability of forest productivity patterns over a large region using TM data and/or TM nested within AVHRR data.

Iverson, Louis R.↗
NASA NTRS1988

Interpreting forest biome productivity and cover utilizing nested scales of image resolution and biogeographical analysis

The objective was to relate spectral imagery of varying resolution with ground-based data on forest productivity and cover, and to create models to predict regional estimates of forest productivity and cover with a quantifiable degree of accuracy. A three stage approach was outlined. In the first stage, a model was developed relating forest cover or productivity to TM surface reflectance values (TM/FOREST models). The TM/FOREST models were more accurate when biogeographic information regarding the landscape was either used to stratigy the landscape into more homogeneous units or incorporated directly into the TM/FOREST model. In the second stage, AVHRR/FOREST models that predicted forest cover and productivity on the basis of AVHRR band values were developed. The AVHRR/FOREST models had statistical properties similar to or better than those of the TM/FOREST models. In the third stage, the regional predictions were compared with the independent U.S. Forest Service (USFS) data. To do this regional forest cover and forest productivity maps were created using AVHRR scenes and the AVHRR/FOREST models. From the maps the county values of forest productivity and cover were calculated. It is apparent that the landscape has a strong influence on the success of the approach. An approach of using nested scales of imagery in conjunction with ground-based data can be successful in generating regional estimates of variables that are functionally related to some variable a sensor can detect.

Iverson, Louis R.↗
NASA NTRS1991

Thermal analysis of the ultraviolet imager camera and electronics

The Ultraviolet Imaging experiment has undergone design changes that necessiate updating the reduced thermal models (RTM's) for both the Camera and Electronics. In addition, there are several mission scenarios that need to be evaluated in terms of thermal response of the instruments. The impact of these design changes and mission scenarios on the thermal performance of the Camera and Electronics assemblies is discussed.

Dirks, Gregory J.↗
NASA NTRS1991

Design and analysis of aspherical multilayer imaging X-ray microscope

Spherical Schwarzschild microscopes for soft X-ray applications in microscopy and projection lithography employ two concentric spherical mirrors that are configured such that the third-order spherical aberration and coma are zero. Based on incoherent, sine-wave MTF calculations, the object-plane resolution of a magnification-factor-20 microscope is presently analyzed as a function of object height and numerical aperture of the primary for several spherical Schwarzschild, conic, and aspherical two-mirror microscope configurations.

Shealy, David L.↗
NASA NTRS1992

Analysis of Voyager 2 images of Jovian lightning

Magalhaes and Borucki (1991) reported that Voyager-2 images of Jupiter contained bright spots due to lightning activity that was confined to two narrow altitude bands centered at 49 deg N and 13.5 deg N latitude and to a single region near 60 deg N latitude. This paper describes the Voyager 2 imaging observations in detail and associates the positions of the lightning features in the images with particular cloud features. The energetics of the lightning storms on Jupiter is examined. It is found that the ratio of the energy dissipated by Jovian lightning to the thermal flux available to drive convection motions is about 3 decades larger than the terrestrial ratio.

Borucki, William J.↗
NASA NTRS1992

A feasibility study of hand kinematics for EVA analysis using magnetic resonance imaging

A new method for analyzing the kinematics of joint motion using magnetic resonance imaging (MRI) is described. The reconstruction of the metacarpalphalangeal joint of the left index finger into a 3D graphic display is shown. From the reconstructed volumetric images, measurements of the angles of movement of the applicable bones are obtained and processed by analyzing the screw motion of the joint. Landmark positions are chosen at distinctive locations of the joint at fixed image threshold intensity levels to ensure repeatability. The primarily 2D planar motion of this joint is then studied using a method of constructing coordinate systems using three or more points. A transformation matrix based on a world coordinate system describes the location and orientation of the local target coordinate system. The findings show the applicability of MRI to joint kinematics for gaining further knowledge of the hand-glove design for EVA.

Dickenson, Reuben D.↗
NASA NTRS1994

Calibration of HST wide field camera for quantitative analysis of faint galaxy images

We present the methods adopted to optimize the calibration of images obtained with the Hubble Space Telescope (HST) Wide Field Camera (WFC) (1991-1993). Our main goal is to improve quantitative measurement of faint images, with special emphasis on the faint (I approximately 20-24 mag) stars and galaxies observed as a part of the Medium-Deep Survey. Several modifications to the standard calibration procedures have been introduced, including improved bias and dark images, and a new supersky flatfield obtained by combining a large number of relatively object-free Medium-Deep Survey exposures of random fields. The supersky flat has a pixel-to-pixel rms error of about 2.0% in F555W and of 2.4% in F785LP; large-scale variations are smaller than 1% rms. Overall, our modifications improve the quality of faint images with respect to the standard calibration by about a factor of five in photometric accuracy and about 0.3 mag in sensitivity, corresponding to about a factor of two in observing time. The relevant calibration images have been made available to the scientific community.

Ratnatunga, Kavan U.↗
NASA NTRS1998

Analysis of Mauna Kea Imaging of Comet Shoemaker-Levy 9

The aim of this proposal was to analyse a set of charge-coupled device images of the Jupiter-impacting comet D/Shoemaker-Levy 9. The images were obtained primarily using the University of Hawaii 2.2-m telescope and a standardized imaging device, providing an unusually uniform set of data. Additional data included a set of spectra taken in search of gaseous emission from SL9 using the UH 2.2-m and Keck 10-m telescopes.

Jewitt, David↗
NASA NTRS2010

Cosmic Infrared Background Fluctuations in Deep Spitzer Infrared Array Camera Images: Data Processing and Analysis

This paper provides a detailed description of the data reduction and analysis procedures that have been employed in our previous studies of spatial fluctuation of the cosmic infrared background (CIB) using deep Spitzer Infrared Array Camera observations. The self-calibration we apply removes a strong instrumental signal from the fluctuations that would otherwise corrupt the results. The procedures and results for masking bright sources and modeling faint sources down to levels set by the instrumental noise are presented. Various tests are performed to demonstrate that the resulting power spectra of these fields are not dominated by instrumental or procedural effects. These tests indicate that the large-scale ([greater, similar]30') fluctuations that remain in the deepest fields are not directly related to the galaxies that are bright enough to be individually detected. We provide the parameterization of these power spectra in terms of separate instrument noise, shot noise, and power-law components. We discuss the relationship between fluctuations measured at different wavelengths and depths, and the relations between constraints on the mean intensity of the CIB and its fluctuation spectrum. Consistent with growing evidence that the [approx]1-5 [mu]m mean intensity of the CIB may not be as far above the integrated emission of resolved galaxies as has been reported in some analyses of DIRBE and IRTS observations, our measurements of spatial fluctuations of the CIB intensity indicate the mean emission from the objects producing the fluctuations is quite low ([greater, similar]1 nW m-2 sr-1 at 3-5 [mu]m), and thus consistent with current [gamma]-ray absorption constraints. The source of the fluctuations may be high-z Population III objects, or a more local component of very low luminosity objects with clustering properties that differ from the resolved galaxies. Finally, we discuss the prospects of the upcoming space-based surveys to directly measure the epochs inhabited by the populations producing these source-subtracted CIB fluctuations, and to isolate the individual fluxes of these populations.

Arendt, Richard↗
NASA NTRS2012

SATPLOT for Analysis of SECCHI Heliospheric Imager Data

Determining trajectories of solar transients such as coronal mass ejections is not always easy. White light images from SECCHI's (Sun Earth Connection Coronal and Heliospheric Investigation) heliospheric imagers are difficult to interpret because they represent a line-of-sight projection of optically thin solar wind structures. A structure's image by itself gives no information about its angle of propagation relative to the Sunspacecraft line, and an image may show a superposition of several structures, all propagating at different angles. Analyzing SECCHI heliospheric imager data using plots of elongation (angle from the Sun) versus time at fixed position angle (aka Jplots ) has proved extremely useful in understanding the observed solar wind structures. This technique has been used to study CME (coronal mass ejection) propagation, CIRs (corotating interaction regions), and blobs. SATPLOT software was developed to create and analyze such elongation versus time plots. The tool uses a library of cylindrical maps of the data for each spacecraft s panoramic field-of-view. Each map includes data from three SECCHI white-light telescopes (the COR2 coronagraph and both heliospheric imagers) at one time for one spacecraft. The maps are created using a Plate Carree projection, optimized for creating the elongation versus time plots. The tool can be used to analyze the observed tracks of features seen in the maps, and the tracks are then used to extract information, for example, on the angle of propagation of the feature.

Hall, Jeffrey R.↗
NASA NTRS2015

Current Status of a NASA High-Altitude Balloon-Based Observatory for Planetary Science

Recent studies have shown that progress can be made on over 20% of the key questions called out in the current Planetary Science Decadal Survey by a high-altitude balloon-borne observatory. Therefore, NASA has been assessing concepts for a gondola-based observatory that would achieve the greatest possible science return in a low-risk and cost-effective manner. This paper addresses results from the 2014 Balloon Observation Platform for Planetary Science (BOPPS) mission, namely successes in the design and performance of the Fine Pointing System. The paper also addresses technical challenges facing the new Gondola for High Altitude Planetary Science (GHAPS) reusable platform, including thermal control for the Optical Telescope Assembly, power generation and management, and weight-saving considerations that the team will be assessing in 2015 and beyond.

predictive filter↗
NASA NTRSDate not supplied

Digital Elevation Map Parametric Error Analysis Using Corresponding NAC Images

Future lunar landing systems, particularly those used to land humans on the lunar surface aspart of the ARTEMIS program, will require precision navigation relative to the lunar surface. The most common way to meet these stringent navigation require-ments is through terrain relative navigation (TRN), which localizes a spacecraft by comparing descent im-agery with a predefined map of the surface. The accu-racy achievable using TRN is limited by the accuracy of the reference Digital Elevation Map (DEM). It is therefore critical for future lunar missions that potential errors in DEMs be quantified. This paper describes one of NASA’s current efforts to develop a process for evaluating lunar DEM quality.

Chris R Gnam↗