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At least 937 records · Page 52
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Evaluate ERTS imagery for mapping and detection of changes of snowcover on land and on glaciers

The author has identified the following significant results. The area of snow cover on land was determined from ERTS-1 imagery. Snow cover in specific drainage basins was measured with the Stanford Research Institute console by electronically superimposing basin outlines on imagery, with video density slicing to measure areas. Snow covered area and snowline altitudes were also determined by enlarging ERTS-1 imagery 1:250,000 and using a transparent map overlay. Under very favorable conditions, snowline altitude was determined to an accuracy of about 60 m. Ability to map snow cover or to determine snowline altitude depends primarily on cloud cover and vegetation and secondarily on slope, terrain roughness, sun angle, radiometric fidelity, and amount of spectral information available. Glacier accumulation area ratios were determined from ERTS-1 imagery. Also, subtle flow structures, undetected on aerial photographs, were visible. Surging glaciers were identified, and the changes resulting from the surge of a large glacier were measured as were changes in tidal glacier termini.

Meier, M. F.↗
NASA NTRS1972

A computer program for modeling non-spherical eclipsing binary star systems

The accurate analysis of eclipsing binary light curves is fundamental to obtaining information on the physical properties of stars. The model described accounts for the important geometric and photometric distortions such as rotational and tidal distortion, gravity brightening, and reflection effect. This permits a more accurate analysis of interacting eclipsing star systems. The model is designed to be useful to anyone with moderate computing resources. The programs, written in FORTRAN 4 for the IBM 360, consume about 80k bytes of core. The FORTRAN program listings are provided, and the computational aspects are described in some detail.

Wood, D. B.↗
NASA NTRS1972

Trinity Bay Study: Dye tracing experiments

An analysis of the heat balance and temperature distribution within Trinity Bay near Galveston, Texas is presented. The effects of tidal currents, wind driven circulations, and large volume inflows are examined. Emphasis is placed on the effects of turbulent diffusion and local shears in currents. The technique of dye tracing to determine the parameters characterizing dispersion is described. Aerial photographs and maps are provided to show the flow conditions existing at different times and seasons.

Ward, G. H., Jr.↗
NASA NTRS1973

Further development and testing of the metabolic gas analyzer

Continued development of a metabolic monitor utilizing a mass spectrometer and digital computer to perform measurements and data reduction, is reported. The device prints-out breath-by-breath values for 02 consumption, C02 production, minute volume and tidal volume. The flow is measured by introduction of a tracer gas to the expired gas stream. Design modifications to reduce pressure drop in the flow splitter to one inch of water at 600 liters/min flow and to extend the range of linear flow measurement to 1000 liters/min are discussed.

Source record↗
NASA NTRS1973

Satellite studies of suspended matter and aquatic interfaces in Delaware Bay

The author has identified the following significant results. Three successful ERTS-1 satellite passes have produced synoptic imagery showing distribution of suspended matter and aquatic interfaces over Delaware Bay and adjacent Atlantic coastal regions. The interfaces are a major hydrographic feature in Delaware Bay and frequently include regions of high convergence. In the upper and middle bay the interfaces tend to align along the flow axis of the river and parallel to the shoreline. A correlation has been found between the concentration of sand particles in suspension and the depth, suggesting that most of the heavier particles are lifted into temporary suspension over shoals and shallow areas by currents and waves. The second type of interface is primarily a tidal intrusion of shelf water into the bay during incipient flood tide, with associated discontinuities in salinity and temperature. The convergence properties of such fronts attract heavy accumulations of foam which were found to contain strong concentrations of heavy metals and other toxic substances.

Klemas, V.↗
NASA NTRS1973

Application of ERTS-1-data to the protection and management of New Jersey's coastal environment

The author has identified the following significant results. New Jersey's planned, regionalized network of sewage disposal facilities has been plotted on an ERTS-1 mosaic and circulation parameters for each of the planned outfall locations have been analyzed using the ERTS-1 imagery and comparative aircraft photography. Work is continuing on the circulation and dispersion of barge-dumped wastes in the New York Bight area. One of the largest remote sensing experiments ever attempted in this country was completed on April 7, 1973 during the ERTS-1 overpass. The test area included the northern portion of New Jersey and the Raritan Bay - New York Harbor area. Three NASA aircraft, two helicopters, nine surface vessels, 40 ground team personnel, and numerous oceanographic, radiometric, and meteorological equipment were deployed in an effort to characterize the surface and near-surface circulation dynamics in this 600 square mile area, during an entire tidal cycle. The analyses of these data in concert with all previous ERTS-1 overpasses will provide information that can lead to a better and more rational use of the nearshore marine environment. The data will be utilized to plan future outfall locations, regulating offshore disposal of wastes, etc.

Yunghans, R. S.↗
NASA NTRS1973

The use of hydrogen for aircraft propulsion in view of the fuel crisis

Some factors influencing the technical feasibility of operating a liquid hydrogen-fueled airplane are discussed in light of the projected decrease of fossil fuels. Other sources of energy, such as wind, tidal, solar, and geothermal, are briefly mentioned. In view of projected decreases in available petroleum fuels, interest has been generated in exploiting the potential of liquid hydrogen (LH2) as an aircraft fuel. Cost studies of LH2 production show it to be more expensive than presently used fuels. Regardless of cost considerations, LH2 is viewed as an attractive aircraft fuel because of the potential performance benefits it offers. Accompanying these benefits, however, are many new problems associated with aircraft design and operations; for example, problems related to fuel system design and the handling of LH2 during ground servicing. Some of the factors influencing LH2 fuel tank design, pumping, heat exchange, and flow regulation are discussed.

Weiss, S.↗
NASA NTRS1972

Equivalent gravity modes - An interim evaluation

The behavior of the main solar semidiurnal tidal mode in a dissipative atmosphere is studied both in a rotating spherical atmosphere and by means of the equivalent gravity mode approximation. Coefficients are chosen to crudely simulate the effects of molecular viscosity and conductivity. Major findings are: (1) Below 130 km, where friction is unimportant, equivalent gravity mode results are, for all practical purposes, identical to those at the equator obtained from a spherical calculation. (2) Above 130 km amplitudes over the equator obtained from the spherical calculation are about 30 percent smaller than those obtained from the equivalent gravity mode calculations. Also, there is a 15 deg (1/2 hour) difference in phase. (3) The amplitude reduction over the equator, is associated with a broadening of the latitude distribution of amplitude for the oscillatory pressure and temperature fields within the thermosphere. There is also significant variation of phase with latitude within the thermosphere. Associated with the above variations are significant changes in the latitude distribution of horizontal velocity within the thermosphere.

Lindzen, R. S.↗
NASA NTRS1973

Application of ERTS-1 data to the protection and management of New Jersey's coastal environment

ERTS-1 imagery is being used by the New Jersey Department of Environmental Protection (NJDEP) to develop information products that will assist the state in optimally managing its coastal resources and in allocating funds. Interviews with NJDEP personnel have identified significant problem areas in the coastal zone, and the types of remote sensor derived information products that can be used in real-time decision making. Initial analyses of imagery from several successive ERTS-1 orbits have shown the extent, predominant drift, and dispersion characteristics of waste disposal in coastal New Jersey waters. Imagery (MSS Bands 4 and 5) for several orbits, shows that New-York Harbor tidal discharge extending as far south as Long Branch, New Jersey.

Mairs, R. L.↗
NASA NTRS1973

Sediment distribution and coastal processes in Cook Inlet, Alaska

Regional hydrologic and oceanographic relationships in Cook Inlet, Alaska have been recognized from sequential ERTS-1 MSS imagery. Current patterns are visible in the inlet because of differential concentrations of suspended sediment. The circulation patterns within Cook Inlet are controlled primarily by the interaction between the semi-diurnal tides and the counter clockwise Alaska current. In general, heavily sediment laden water is seen to be confined to portions of the inlet north of the Forelands and west of Kalgin Island. Tongues of clear oceanic water are observed to enter the inlet through Kennedy Channel along the east shoreline in the vicinity of Cape Elizabeth. A recurring counterclockwise circulation pattern observed around Kalgin Island seems to result from the interplay of the northerly moving water along the east shore and the southerly moving, sediment laden, water along the west side of the inlet. Prominent, fresh water plumes, heavily laden with sediment are visible at the mouths of all major rivers. Relect plumes from as many as three tidal stages have been recognized.

Anderson, D. M.↗
NASA NTRS1973

Distribution and movement of suspended sediment in the Gulf of Mexico off the Texas coast

ERTS-1 imagery has proven very useful in studies of the distribution of suspended sediment in the Gulf of Mexico off the Texas coast. Moreover, by using suspended matter concentrations as tags on water masses, much information on water movement can be obtained. The utility of suspended sediment as a tracer is dependent on the sediment remaining in suspension long enough to travel an appreciable distance or to be visible on successive images. Although the evidence is not conclusive, it seems likely that much of the suspended sediment in Gulf of Mexico nearshore waters during normal seastate conditions has remained in suspension since the time of its entry into the Gulf of Mexico through rivers and tidal inlets.

Hunter, R. E.↗
NASA NTRS1973

Application of ERTS-1 imagery in coastal studies

The basic ERTS output is four black-and-white photographs presenting the same scene recorded in each multispectral scanner band. Mosaics covering large regions at a 1:250,000 scale can be compiled from these photographs. Office study of the image of each band separately, in combination with other bands, and in conjunction with other available data (navigation charts, tide tables, etc.) permits extraction of data useful in coastal engineering planning and coastal processes studies. Specific examples in which significant information on regional shoreline configuration or nearshore water movements has been obtained from unenhanced ERTS imagery are: (1) tidal inlet configuration; (2) navigation information; and (3) nearshore water movements.

Magoon, O. T.↗
NASA NTRS1973

Estuary and barrier island study

The author has identified the following significant results. Scan line distortion is apparent in ERTS-1 imagery, imparting a serrated-edge appearance to shorelines. This feature however does not hinder observation and interpretation of broad features such as shoaling areas and sediment plumes. Shoaling in the backshore areas and inlets is easily discernible in spectral bands 4 and 5. Contrast between land and water is especially striking in spectral band 7, allowing easy identification of tidal flat areas.

Berg, D. W.↗
NASA NTRS1973

Techniques for the analysis of geodynamic effects using laser data

New orbit computation techniques have been developed to realize the full precision of laser ranging measurements from a single tracking station used to accurately determine the orbital inclination of a satellite. In order to evaluate earth and ocean tidal effects on the satellite and polar motion effects on the station latitude, improved computational techniques are described for perturbations significantly influencing the satellite's inclination, such as solar radiation pressure and geopotential resonance. By using the time independent value of maximum latitude reached by the satellite as the experimental variable, orbit tracking errors caused by imprecise modelling of the gravity field and atmospheric drag have been largely overcome and made possible long term analysis of osculating elements. With these techniques, quarter day spans of laser data have been employed to monitor the inclination of the satellite to the order 0.01 arcseconds precision over a period of seventeen months.

Dunn, P. J.↗
NASA NTRS1973

Polar motion

Tracking of the Beacon Explorer-C satellite by a precision laser system was used to measure the polar motion and solid earth tide. The tidal perturbation of satellite latitude is plotted as variation in maximum latitude in seconds of arc on earth's surface as a function of the date, and polar motion is shown by plotting the variation in latitude of the laser in seconds of arc along the earth's surface as a function of date

Kolenkiewicz, R.↗
NASA NTRS1973

On the establishment and evolution of orbit-orbit resonances

A theory which suggests that in the case of planetary satellites, a tidally induced torque acting on the satellites may play an essential role on the evolution of the observed resonances is investigated as it applies to the three resonances among pairs of satellites of Saturn. Three stages are investigated: a theoretical description of transition is developed for a simple time dependent pendulum plus constant applied torque; the two body gravitational interaction is expanded and reduced to a one dimensional time independent Hamiltonion; and the model is applied to Saturn resonances. Although the theory proves successful in the Saturn case, it is less successful in the Tital-Hyperion case in providing a resonable time scale for the damping of the amplitude of liberation.

Yoder, C. F.↗
NASA NTRS1972

Geodetic studies by laser ranging to satellites.

For three months in 1970, two Goddard Space Flight Center (GSFC) laser tracking systems were used to try to detect the motion of the pole of rotation of the earth. More than two hundred passes of the Beacon Explorer C spacecraft were observed as it passed between the two stations, and these data were used to determine the orbital inclination of the spacecraft. The analysis required the accurate determination of the relative positions of the two tracking stations and the identification of the perturbations to the spacecraft orbit, in particular, those due to the gravitational fields of the earth, sun, and moon and those caused by the solid-earth tides. The results to date indicate that the GSFC laser systems can determine interstation distances with a repeatability of about 25 cm and that a new value of the Love number k that represents the distortion of the earth's gravity field caused by the tidal deformation of the earth is 0.35 plus or minus 0.05.

Smith, D. E.↗
NASA NTRS1973

Models for compact pulsing X-ray sources.

Development of a model of a neutron star (Cen X-3) which releases the infall energy of accreted matter. Some general remarks are made on the possibility of accretion as a source of energy. It is shown that overflow of the Roche lobe is neither necessary as a source of mass nor probable in view of the observed stellar line widths of the two identified X-ray companions. While not excluding the possibility that tidal forces may drive some mass outflow, a number of models are investigated in which the material to be accreted appears in the form of a stellar wind. The behavior of the accreted gas near the accreting object is discussed, as well as the transfer of angular momentum near the accreting object. It is concluded that a relatively simple stellar wind driven accretion model appears to satisfactorily account, in a quantitative but not precise way, for most of the observed features of Cen X-3.

Ostriker, J. P.↗