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At least 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Alignment techniques required by precise measurement of effective focal length

The characteristics of false color imagery produced by instrumentation on earth resource mapping satellites are examined. The spatial fidelity of the imagery is dependent upon the geometric accuracy (GA) and the band-to-band registration (BBR) with which the telescope instrument is assembled. BBR and GA require knowledge of telescope effective focal length (EFL) to one part in 10,000 in order that the next generation of earth mappers be able to carry out their missions. The basis for this level of precision is briefly considered, and a description is given of the means by which such precise EFL measurements have been carried out. Attention is given to accuracy requirements, the technique used to measure effective focal length, possible sources of error in the EFL measurement, approaches for eliminating errors, and the results of the efforts to control measurement errors in EFL determinations.

Wise, T. D.↗
NASA NTRS1981

Seasat radar geomorphic applications in coastal and wetland environments, southeastern U.S

The application of Seasat Synthetic Aperture Radar (SAR) to the assessment of terrain conditions in coastal environments is considered. Drainage patterns and plant community spatial relationships can be adequately mapped as is shown by Seasat L-band imagery of the southeastern Gulf Coast and Atlantic Coastal Plain. Anomalously bright radar signatures are identified as characteristic of mangrove and cypress swamps. Marshes have a low radar return, less than that from non-marsh areas and open water in tidal channels. Drainage patterns for coastal plain transition zones can also be determined. Spaceborne imaging radar provides information which complements geomorphic analyses presently obtained with optical sensors.

Macdonald, H. C.↗
NASA NTRS1985

VLA continuum observations of compact H II regions

The VLA interferometer has been used to obtain 5 GHz continuum observations of the galactic H II regions W48, G25.4 - 0.2S, G8.1 + 0.2, and G89.1 + 1.3, at less than 6-arcsec spatial resolution. From the source maps presented, H II region physical parameters are derived and tentative models for the G25.4-0.2S H II region, employing the VLA radio interferometric map and available IR data, are discussed.

Woodward, C. E.↗
NASA NTRS1986

The Columbia CO survey of molecular clouds in the first galactic quadrant

A systematic, unbiased survey of CO emission from much of the first Galactic quadrant has been completed using the Columbia-Goddard millimeter wave telescope. The velocity resolution is 1.3 km/s and the coverage is from -13 to 153 km/s at latitude less than 55 deg and from -55 to 111 km/s at latitudes of 55 deg and higher. The noise is 0.45 K rms per 1/3 km/s resolution element. The instrument and observing technique are described and the instrument's calibration is compared with that of other telescopes. When the different beams are taken into account, the calibration agrees well with measurements of individual molecular clouds and the Galactic plane done with both the Bell Laboratories 7 m and the NRAO 11 m telescopes. The entire collection of over 3000 spectra are presented along with spatial and longitude-velocity maps.

Cohen, R. S.↗
NASA NTRS1987

Kinematics at the intersection of the Garlock and Death Valley fault zones, California: Integration of TM data and field studies

The Garlock and Death Valley fault zones in SE California are two active strike-slip faults coming together on the east side of the Avawatz Mtns. The kinematics of this intersection, and the possible continuation of either fault zone, are being investigated using a combination of field mapping, and processing and interpretation of remotely sensed image data. Regional and local relationships are derivable from Thematic Mapper data (30 m resolution), including discrimination and relative age dating of alluvial fans, bedrock mapping, and fault mapping. Aircraft data provide higher spatial resolution over more limited areas. Hypotheses being considered are: (1) the Garlock fault extends east of the intersection; (2) the Garlock fault terminates at the intersection and the Death Valley fault continues southeastward; and (3) the Garlock fault has been offset right laterally by the Death Valley fault which continues to the southeast. Preliminary work indicates that the first hypothesis is invalid. From kinematic considerations, image analysis, and field work the third hypothesis is favored. The projected continuation of the Death Valley zone defines the boundary between the Mojave crustal block and the Basin and Range block.

Abrams, Michael↗
NASA NTRS1988

An albedo map of P/Halley on 13 March 1986

An albedo map is presented of comet Halley from a 10 micrometer image taken from the Wyoming Infrared Observatory on 13 Mar. 1986, and a 7311 A CCD image taken from the Anglo-Australian Telescope about an hour later. To construct this map, the CCD image was first converted from 0.49 arcsec/pixel to 1 arcsec/pixel to match the scale of the 10 micron image, then both were calibrated in lambda F sub lambda units. According to the albedo map, most of the inner coma of Halley lies between gamma = 0.04 and 0.08. The overall smoothness of the map is remarkable considering the large dynamic range of the optical and IR maps, and the differences in spatial resolution and image processing.

Hayward, Thomas L.↗
NASA NTRS1989

Far-infrared and submillimeter photometric mapping of spiral galaxies in the Virgo cluster

Three 'normal' Virgo cluster spiral galaxies, NGC 4254, NGC 4501, and NGC 4654, were mapped at 160 and 360 micron wavelengths with arrays of 45 arcsec beams using the NASA Kuiper Airborne Observatory and the NASA Infrared Telescope Facility. Another galaxy, NGC 4321, was mapped at 160 microns. Approximately one-third of the total flux from the galaxies is emitted at wavelengths longer than 12 microns. The maps show centrally peaked, but spatially extended luminosity distributions consistent with disk material.

Stark, A. A.↗
NASA NTRS1992

Studies of extra-solar Oort Clouds and the Kuiper disk

In 1991 we detected extended 1.1 mm emission around Fomalhaut (alpha PsA) at distances in order of magnitude beyond previous detections. This emission is plausibly related to the presence of an extended comet cloud, like our Oort Cloud, and may therefore represent indirect evidence for the formation of a planetary system at Fomalhaut. We propose now to extend this work to create a map of the angular and spatial extent of this emission. Fomalhaut is the only known main-sequence, submm-resolved IR excess source besides beta Pic.

Stern, S. Alan↗
NASA NTRS1992

Very high spatial resolution two-dimensional solar spectroscopy with video CCDs

We have developed techniques for recording and reducing spectra of solar fine structure with complete coverage of two-dimensional areas at very high spatial resolution and with a minimum of seeing-induced distortions. These new techniques permit one, for the first time, to place the quantitative measures of atmospheric structure that are afforded only by detailed spectral measurements into their proper context. The techniques comprise the simultaneous acquisition of digital spectra and slit-jaw images at video rates as the solar scene sweeps rapidly by the spectrograph slit. During data processing the slit-jaw images are used to monitor rigid and differential image motion during the scan, allowing measured spectrum properties to be remapped spatially. The resulting quality of maps of measured properties from the spectra is close to that of the best filtergrams. We present the techniques and show maps from scans over pores and small sunspots obtained at a resolution approaching 1/3 arcsec in the spectral region of the magnetically sensitive Fe I lines at 630.15 and 630.25 nm. The maps shown are of continuum intensity and calibrated Doppler velocity. More extensive spectral inversion of these spectra to yield the strength of the magnetic field and other parameters is now underway, and the results of that analysis will be presented in a following paper.

Johanneson, A.↗
NASA NTRS1997

A Study of the Stellar Population in Selected SO Galaxies

The goal of this program was to observe at least two SO galaxies with abnormal colors in the blue and clear optical signatures of dust and gas. The galaxies NGC 2217 and NGC 1808 were observed at least in one of the IUE cameras (1200-200 and 2000-3200 A) during the 13th episode, using the 4 US1 shifts assigned to this program. The galaxy NGC 2217 had been found to be part of a subgroup of SO galaxies with external gas rotating in retrograde motion with respect to the stars. This galaxy is a face-on object with indications of large amount of gas, quite rare for a SO galaxy. We observed this object on three different occasions with IUE at different positions of the large aperture (spacecraft roll angle) with respect to the nuclear region. These exposures allowed us to take full advantage of the spatial resolution of IUE by mapping nuclear and bulge region of this galaxy. We found that the data point to a marginally earlier stellar population toward the central region. The UV light as a whole is dominated by a late-type stellar population of principally G and K stars. The almost face-on view of this galaxy appears optically thick to UV light. It is conceivable that in analogy to out own Galaxy, the stellar populations weakly detected in NGC 2217, are mostly halo and late-type stars in the center with an increasing contribution of dust and early stellar populations (so far undetected) as we move outward along the faint spiral arms. This result is contrary to our initial expectation, since the counterrotating gas does not appear to be enhancing star formation in this galaxy. Even more interesting were the observations of NGC 1808; galaxy which has been classified, with a handful of other objects, both as a starburst and Seyfert galaxy. Attachment: 'The White-Dwarf Companions of 56 Persei and HR 3643.'

Perez, M.↗
NASA NTRS1999

Data Processing for the Near Earth Asteroid Rendezvous (NEAR), X-ray and Gamma-ray Spectrometer (XGRS) Ground System

An X-ray and Gamma-ray spectrometer (XGRS) is onboard the Near Earth Asteroid Rendezvous (NEAR) spacecraft to determine the elemental composition of the surface of the asteroid 433Eros. The Eros asteroid is highly non-spherical in physical shape and the development of data management and analysis methodologies are in several areas a divergence from traditional remotely sensed geographical information systems techniques. Field of view and asteroid surface geometry must be derived virtually and then combined with real measurements of solar, spectral and instrument calibration information to derive meaningful scientific results. Spatial resolution of planned geochemical maps will be improved from the initial conditions of low statistical significance per integration by repeated surface flyovers and regional spectral accumulation. This paper describes the results of a collaborative effort of design and development of the NEAR XGRS instrument ground system undertaken by participants at the Goddard Space Flight Center, University of Arizona, Cornell University, Applied Physics Laboratory, and Max Plank institute.

McClanahan, Timothy P.↗
NASA NTRS1999

Planetary Nebulae with Supporting IR Data

We present new HST/WFPC2 imagery for the planetary nebula (PN) NGC 6818. Observations were made in line filters F437N, F487N, F502N, and F656N plus continuum filter F547M. The primary goal was to develop a high spatial resolution (approx. 0.1 in.) map of the intrinsic line ratio [O III] 4363/5007 and thereby evaluate the electron temperature (T(sub e)) and the mean-square T(sub e) variation (t(sup 2) across the PN. In this process we developed an extinction map from the F487N (H(beta)) and F656N (H(alpha)) images by comparing the observed line ratios in each pixel to the theoretical ratio and computing a c(H(beta)) map which was used to correct the observed 4363/5007 ratios for reddening. We also adjust for the continuum contribution to the line filter data. We present color-coded pictures of the reddening (c(H(beta))) map, the [O III] T(sub e) map, as well as our determinations of t(sup 2). The T(sub e) map shows a decline from approx. 14000 K in the inner regions to approx. 11000 K at the outer edge. Such a radial T(sub e) gradient is expected for a high-excitation nebula with a prominent He(++) zone such as NGC 6818. A composite of images taken in 3 filters (F656N, red; F487N, blue; and F502N, [O III] 5007, green) shows a roughly spherical outer envelope as well as a brighter vase-shaped interior "bubble". There is a prominent orifice to the North and a smaller one to the South, along the major axis, possibly caused by a blow-out from a fast wind. This nebula has an appearance remarkably similar to that of the PN NGC 3918 previously imaged with HST by H. Bond. We note from the continuum images (F547M) two stars in the nebular field that are fainter than the prominent central star; these are roughly 2-4 sec. N and NE of the central star. Further study is needed to establish whether or not there may be a physical association of either star with the central star.

Harrington, J. Patrick↗
NASA NTRS1999

Data Processing for the Near Earth Asteroid Rendezvous (NEAR), X-Ray and Gamma-Ray Spectrometer (XRS) Ground System

An X-ray and Gamma-ray spectrometer (XGRS) is onboard the Near Earth Asteroid Rendezvous (NEAR) spacecraft to determine the elemental composition of the surface of the asteroid 433Eros. The Eros asteroid is highly non-spherical in physical shape and the development of data management and analysis methodologies are in several areas a divergence from traditional remotely sensed geographical information systems techniques. Field of view and asteroid surface geometry must be derived virtually and then combined with real measurements of solar, spectral and instrument calibration information to derive meaningful scientific results. Spatial resolution of planned geochemical maps will be improved from the initial conditions of low statistical significance per integration by repeated surface flyovers and regional spectral accumulation. This paper describes the results of a collaborative effort of design and development of the NEAR XGRS instrument ground system undertaken by participants at the Goddard Space Flight Center, University of Arizona, Cornell University, Applied Physics Laboratory, and Max Plank institute.

McClanahan, Timothy P.↗
NASA NTRS2003

EOS-Aura's Ozone Monitoring Instrument (OMI): Validation Requirements

OMI is an advanced hyperspectral instrument that measures backscattered radiation in the UV and visible. It will be flown as part of the EOS Aura mission and provide data on atmospheric chemistry that is highly synergistic with other Aura instruments HIRDLS, MLS, and TES. OMI is designed to measure total ozone, aerosols, cloud information, and UV irradiances, continuing the TOMS series of global mapped products but with higher spatial resolution. In addition its hyperspectral capability enables measurements of trace gases such as SO2, NO2, HCHO, BrO, and OClO. A plan for validation of the various OM1 products is now being formulated. Validation of the total column and UVB products will rely heavily on existing networks of instruments, like NDSC. NASA and its European partners are planning aircraft missions for the validation of Aura instruments. New instruments and techniques (DOAS systems for example) will need to be developed, both ground and aircraft based. Lidar systems are needed for validation of the vertical distributions of ozone, aerosols, NO2 and possibly SO2. The validation emphasis will be on the retrieval of these products under polluted conditions. This is challenging because they often depend on the tropospheric profiles of the product in question, and because of large spatial variations in the troposphere. Most existing ground stations are located in, and equipped for, pristine environments. This is also true for almost all NDSC stations. OMI validation will need ground based sites in polluted environments and specially developed instruments, complementing the existing instrumentation.

Brinksma, E. J.↗
NASA NTRS2005

Lunar and Planetary Science XXXVI, Part 13

Contents include the following: A Fast, Non-Destructive Method for Classifying Ordinary Chondrite Falls Using Density and Magnetic Susceptibility. An Update on Results from the Magnetic Properties Experiments on the Mars Exploration Rovers, Spirit and Opportunity. Measurement Protocols for In Situ Analysis of Organic Compounds at Mars and Comets. Piping Structures on Earth and Possibly Mars: Astrobiological Implications. Uranium and Lead in the Early Planetary Core Formation: New Insights Given by High Pressure and Temperature Experiments. The Mast Cameras and Mars Descent Imager (MARDI) for the 2009 Mars Science Laboratory. MGS MOC: First Views of Mars at Sub-Meter Resolution from Orbit. Analysis of Candor Chasma Interior Layered Deposits from OMEGA/MEX Spectra. Analysis of Valley Networks on Valles Marineris Plateau Using HRSC/MEX Data. Solar Abundance of Elements from Neutron-Capture Cross Sections. Preliminary Evaluation of the Secondary Ion/Accelerator Mass Spectrometer, MegaSIMS. Equilibrium Landforms in the Dry Valleys of Antarctica: Implications for Landscape Evolution and Climate Change on Mars. Continued Study of Ba Isotopic Compositions of Presolar Silicon Carbide Grains from Supernovae. Paleoenviromental Evolution of the Holden-Uzboi Area. Stability of Magnesium Sulfate Minerals in Martian Environments. Tungsten Isotopic Constraints on the Formation and Evolution of Iron Meteorite Parent Bodies. Migration of Dust Particles and Volatiles Delivery to the Inner Planets. On the Sitting of Trapped Noble Gases in Insoluble Organic Matter of Primitive Meteorites. Trapping of Xenon Upon Evaporation-Condensation of Organic Matter Under UV Irradiation: Isotopic Fractionation and Electron Paramagnetic Resonance Analysis. Stability of Water on Mars. A Didactic Activity. Analysis of Coronae in the Parga Chasma Region, Venus. Photometric and Compositional Surface Properties of the Gusev Crater Region, Mars, as Derived from Multi-Angle, Multi-Spectral Investigation of Mars Express HRSC Data. Mapping Compositional Diversity on Mars: Spatial Distribution and Geological Implications. A New Simulation Chamber for Studying Planetary Environments. Folded Structure in Terra Sirenum. Mars. Nitrogen-Noble Gas Static Mass Spectrometry of Genesis Collector Materials. Neon Isotope Heterogeneity in the Terrestrial Mantle: Implication for the Acquisition of Volatile Elements in Terrestrial Planets. The Cosmic Clock, the Cycle of Terrestrial Mass Extinctions.

Source record↗
NASA NTRS1993

Video Animation of Ocean Topography From TOPEX/POSEIDON

Three video loops showing various aspects of the dynamic ocean topography obtained from the TOPEX/POSEIDON radar altimetry data will be presented. The first shows the temporal change of the global ocean topography during the first year of the mission. The time-averaged mean is removed to reveal the temporal variabilities. Temporal interpolation is performed to create daily maps for the animation. A spatial smoothing is also performed to retain only the large-sale features. Gyre-scale seasonal changes are the main features. The second shows the temporal evolution of the Gulf Stream. The high resolution gravimetric geoid of Rapp is used to obtain the absolute ocean topography. Simulated drifters are used to visualize the flow pattern of the current. Meanders and rings of the current are the main features. The third is an animation of the global ocean topography on a spherical earth. The JGM-2 geoid is used to obtain the ocean topography...

Fu, Lee-Lueng↗
NASA NTRS2010

JWST Planetary Observations Within the Solar System

JWST provides capabilities unmatched by other telescopic facilities in the near to mid infrared part of the electromagnetic spectrum. Its combination of broad wavelength range, high sensitivity and near diffraction-limited imaging around two microns wavelength make it a high value facility for a variety of Solar System targets. Beyond Neptune, a class of cold, large bodies that include Pluto, Triton and Eris exhibits surface deposits of nitrogen, methane, and other molecules that are poorly observed from the ground, but for which JWST might provide spectral mapping at high sensitivity and spatial resolution difficult to match with the current generation of ground-based observatories. The observatory will also provide unique sensitivity in a variety of near and mid infrared windows for observing relatively deep into the atmospheres of Uranus and Neptune, searching there for minor species. It will examine the Jovian aurora in a wavelength regime where the background atmosphere is dark. Special provision of a subarray observing strategy may allow observation of Jupiter and Saturn over a larger wavelength range despite their large surface brightnesses, allowing for detailed observation of transient phenomena including large scale storms and impact-generation disturbances. JWST's observations of Saturn's moon Titan will overlap with and go beyond the 2017 end-of-mission for Cassini, providing an important extension to the time-series of meteorological studies for much of northern hemisphere summer. It will overlap with a number of other planetary missions to targets for which JWST can make unique types of observations. JWST provides a platform for linking solar system and extrasolar planet studies through its unique observational capabilities in both arenas.

Lunine, Jonathan↗
NASA NTRS2006

Pilot Weather Advisor System

The Pilot Weather Advisor (PWA) system is an automated satellite radio-broadcasting system that provides nearly real-time weather data to pilots of aircraft in flight anywhere in the continental United States. The system was designed to enhance safety in two distinct ways: First, the automated receipt of information would relieve the pilot of the time-consuming and distracting task of obtaining weather information via voice communication with ground stations. Second, the presentation of the information would be centered around a map format, thereby making the spatial and temporal relationships in the surrounding weather situation much easier to understand

Lindamood, Glenn↗