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  • GEOPHYSICS  (1,182)
  • COMMUNICATIONS  (315)
  • 1970-1974  (1,497)
  • 1950-1954
  • 1945-1949
  • 1935-1939
  • 1972  (1,497)
  • 1951
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  • 1970-1974  (1,497)
  • 1950-1954
  • 1945-1949
  • 1935-1939
Year
  • 1
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    Organic geochemistry of Early Precambrian sediments (1972)
    In:  Other Sources
    Details
    Publication Date: 2011-12-21
    Keywords: GEOPHYSICS
    Type: Life Sci. Publ., Vol. 2; 11 p
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  • 2
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    Chemistry of the upper atmosphere and the role of transport processes (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: The important chemical reaction affecting the neutral composition of the upper stratosphere, mesosphere, and lower thermosphere is discussed. The role of atmospheric transport processes is emphasized and the problem of taking these into account is elucidated.
    Keywords: GEOPHYSICS
    Type: NASA, Washington Phys. of the Space Environment; p 147-155
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  • 3
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    Transient heating in the upper atmosphere (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: The time-dependent response of the upper atmosphere to transient heat sources is considered. The basic problem is that of heating a compressible, heat-conducting fluid, which is described in the one-dimensional case by an analytic solution. Comparisons with satellite drag data of such first-order solutions are shown to be useful in determining energy requirements and in determining some constraints on the spatial distribution of the heating. Recent OGO-6 mass spectrometer and interferometric temperature measurements show that atmospheric disturbances during geomagnetic storms are much more prominent in the auroral zones. These results suggest that joule dissipation of auroral currents are important contributors to orbital perturbations of satellites.
    Keywords: GEOPHYSICS
    Type: NASA, Washington Phys. of the Space Environment; p 3-23
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  • 4
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    Dissipation of electric fields in the ionosphere (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: The heating and movement of the upper atmosphere at ionospheric levels in response to electric currents are discussed. Joule dissipation, generation of winds, and pressure gradients are significant factors in the energetics of the ionospheric electric currents flowing during magnetic storms and also of the Sq current system.
    Keywords: GEOPHYSICS
    Type: NASA, Washington Phys. of the Space Environment; p 25-40
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  • 5
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    Antenna drive system for the Nimbus satellite (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: A two-axis drive system is described for pointing a high gain antenna. Motion about each axis is provided by identical drive mechanisms. Only three gear passes are required to obtain the necessary 900:1 gear reduction. The drive system is a primary element of an experiment that will provide a real time data link between Nimbus and ground stations. Data are transmitted from Nimbus to the applications technology satellite, which relays the data to ground stations.
    Keywords: COMMUNICATIONS
    Type: NASA. Ames Res. Center 6th Aerospace Mech. Symp.; p 117-120
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  • 6
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    The Intelsat 4 antenna positioner (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: The Intelsat 4 communications satellite has two spot beam antennas which are pointed to selected land masses by gimbaled positioners. The positioners employ drive motors with electromagnetic brakes and jackscrews that are self-caging during the launch. The positioner uses dry lubricants for ball bearings, spur gears, screw and nut, and various journal bearings. A coefficient of friction of approximately 0.05 was demonstrated in vacuum operation. Success of the positioner was demonstrated on the first Intelsat 4 placed in orbit in January 1971. The developmental problems that were encountered and their solutions are discussed.
    Keywords: COMMUNICATIONS
    Type: NASA. Ames Res. Center 6th Aerospace Mech. Symp.; p 109-116
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  • 7
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    Nimbus observation of oceanic upwelling (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: Observing the development of upwelling on the northeast coast of Africa by measuring ocean surface emission with infrared radiometers on Nimbus satellites is reported. Using the temperature of the ocean as telemetered by the satellite, the biological potential of an area is estimated, and consequently the highest potential for fisheries.
    Keywords: GEOPHYSICS
    Type: Significant Accomplishments in Sci., 1970; p 14-17
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  • 8
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    Locations of solar radio bursts (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: Measurements of the positions of the sources of solar radio bursts at decameter wavelengths, 20- to 60-MHz range, provide information about physical conditions in a region of the corona extending from about one-half to several solar radii from the surface of the sun. Position measurements in the 20- to 60-MHz range were made with the Clark Lake sweep-frequency grating interferometer. Although the resolution of the instrument is sufficient to measure source position accurately, the highly variable effect of refraction in the earth's ionosphere severely limits the observations, distorting position determinations to such an extent as to make much of the position data useless unless ionospheric refraction can be taken into account. A method was developed for the removal of the refractive effect from the data to permit determination of true source position. With this technique it is considered possible to measure spatial extent of radio sources that will provide information about emission processes and physical parameters in the corona.
    Keywords: COMMUNICATIONS
    Type: Significant Accomplishments in Sci., 1970; p 149-153
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  • 9
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    Microwave emission of Arctic Sea ice (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: The feasibility of carrying microwave radiometers on Nimbus E and F missions for sea ice surveys was studied in the arctic using aircraft. It was found that passive microwave signatures of Arctic Sea ice relate specifically to the structure and type of ice. It is concluded that a new tool for conducting ice surveys from aircraft and satellites with remote sensors was discovered.
    Keywords: GEOPHYSICS
    Type: Significant Accomplishments in Sci., 1970; p 18-21
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  • 10
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    Electron impact ionization of H (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: The results of theoretical calculations for the reactions between electrons and negative hydrogen atoms are discussed for an electron colliding with a negative hydrogen ion and neutralizing the hydrogen ion by stripping the loosely bound electron from it, and the two free electrons moving away. A semi-quantum description of the process is presented in which the target is described in terms of quantum mechanics, and the projectile electron is described in a classical fashion.
    Keywords: GEOPHYSICS
    Type: Significant Accomplishments in Sci., 1970; p 58-62
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  • 11
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    Reduction of near-in sidelobes using phase reversal aperture rings (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: A technique is described for reducing near-in sidelobes in spacecraft antennas by cancellation. This technique takes a small portion of the radiation from the antenna aperture and generates the near-in lobes, which are then fed out of phase relative to the main signal. Results of sample cases indicate that the first three lobes can be nearly eliminated at a 40% reduction in aperture efficiency.
    Keywords: COMMUNICATIONS
    Type: JPL Quart. Tech. Rev., Vol. 1, No. 4; p 34-42
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  • 12
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    Bearing strength of the lunar soil (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: A discussion is presented on the bearing strength and bearing load-penetration relations in lunar soil. These were measured in air as a function of bulk density. It was found that the relation between bulk density and the logarithm of the bearing capacity is about linear. Shapes of the load vs penetration curves were observed to be similar to those obtained with particulate material of terrestrial origin.
    Keywords: GEOPHYSICS
    Type: NASA, Washington Analysis of Surveyor 3 Mater. and Phot. Returned by Apollo 12; p 227-232
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  • 13
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    The Goddard helical tape recorder (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: A spacecraft recorder was developed with the objective of functioning continuously for 5 years. The resulting design employed a metallic tape wound in a 200-turn helix. A direct drive, brushless dc torquer and servo speed control drove the recorder at 3 rpm for recording and 54 rpm for playback.
    Keywords: COMMUNICATIONS
    Type: 6th Aerospace Mech. Symp.; p 89-93
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  • 14
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    Comparison of probe and radar ionosphere temperatures (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: The discrepancy in temperature measurements of ionospheric electrons by Langmuir electrostatic probes, and radar backscatter are discussed. The discrepancy occurs at altitudes from 350 to 800km, and the probe temperatures are consistantly higher than the radar temperatures. It is concluded that the non-Maxwellian energy distribution provides an explanation for the altitude and the lower radar temperatures.
    Keywords: GEOPHYSICS
    Type: Significant Accomplishments in Sci., 1970; p 43-45
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  • 15
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    Microwave measurements of sea state (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: Passive microwave measurements were studied for determining sea state. It was found that the brightness temperature increases due to the foam produced by winds, and that the surface wind can be determined by the brightness temperature.
    Keywords: GEOPHYSICS
    Type: Significant Accomplishments in Sci., 1970; p 22-27
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  • 16
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    Bias and spread in extreme value theory measurements of probability of error (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: Extreme value theory is examined to explain the cause of the bias and spread in performance of communications systems characterized by low bit rates and high data reliability requirements, for cases in which underlying noise is Gaussian or perturbed Gaussian. Experimental verification is presented and procedures that minimize these effects are suggested. Even under these conditions, however, extreme value theory test results are not particularly more significant than bit error rate tests.
    Keywords: COMMUNICATIONS
    Type: JPL Quart. Tech. Rev., Vol. 1, No. 4; p 58-68
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  • 17
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    Calibration of radar data from Apollo 16 results, part X (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: Predictions of surface and near surface blockiness using earth based radar measurements were made. Two polarizations of the radar echoes were measured - polarized and depolarized. Particular attention was given to the depolarized echoes. North Ray and South Ray Craters and a 512-m diameter lunar crater in the Flamsteed Ring were used for the study.
    Keywords: COMMUNICATIONS
    Type: NASA. Lyndon B. Johnson Space Center Apollo 16 Prelim. Sci. Rept.; 3 p
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  • 18
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    Bistatic-radar investigation (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: The purpose of the reported experiment was to determine the principal electromagnetic and structural properties of the lunar surface from the observation of command and service module (CSM) radio transmissions that were reflected from the lunar surface and received on earth. These transmissions emanate from the CSM communication systems at wavelengths of 13 cm (S-band) and 116 cm (very high frequency (VHF)). Lunar crustal properties such as dielectric constant, average slope and slope probability, density, small-scale surface roughness, and embedded rocks to a depth of 20 m may be determined. The results are proving to be most useful in understanding the processes that have produced and modified the crust and in distingushing between adjacent and subjacent geological units. The experimental observations are also of intrinsic interest in the study of electromagnetic scattering.
    Keywords: COMMUNICATIONS
    Type: NASA. Lyndon B. Johnson Space Center Apollo 16 Prelim. Sci. Rept.; 13 p
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  • 19
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    The energy balance of wind waves and the remote sensing problem (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: Measurements of wave growth indicate an energy balance of the wave spectrum governed primarily by input from the atmosphere, nonlinear transfer to shorter and longer waves, and advection. The pronounced spectral peak and sharp low frequency cut-off characteristic of fetch-limited spectra are explained as a self-stabilizing feature of the nonlinear wave-wave interactions. The momentum transferred from the atmosphere to the wind waves accounts for a large part of the wind drag. These findings are relevant for remote microwave sensing of the sea surface by backscatter and passive radiometry methods.
    Keywords: GEOPHYSICS
    Type: NOAA Sea Surface Topography from Space, Vol. 2; 55 p
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  • 20
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    Comments on ocean circulation with regard to satellite altimetry (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: Basic features of sea surface topography are reviewed, to show those oceanographic results which may be of value to a geodetic satellite program: (1) the shape and magnitude of the large scale features of the mean sea surface, relative to a level surface; (2) the position and magnitude of the slopes across the western boundary currents, from a variety of data; (3) an estimate of the position of the geoid, tied into the U.S. leveling network; and (4) a documented change of 60 to 70 cm in mean sea level, with respect to the geoid, between the U.S. east and west coasts.
    Keywords: GEOPHYSICS
    Type: NOAA Sea Surface Topography from Space, Vol. 2; 17 p
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  • 21
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    The stable auroral red arc of October 31 - November 1, 1968 and its interaction with the neutral atmosphere (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: Satellite observations of electron temperature and the topside electron density structure are used to calculate the red arc according to the thermal conduction model. In this model, energy from the magnetosphere flows in the electron gas along geomagnetic field lines into the ionosphere. This energy heats the ambient F-region electrons sufficiently to excite the oxygen atoms to the O I(1D) level by collisional impact giving rise to the 6300 A emission characteristic of the arc. For the 31 October/1 November 1968 red arc, the calculated emission rate, geographical position, and horizontal extent of the red arc are in agreement with the photometric data obtained by airglow observatories. Almost all of the energy conducted into the red arc is ultimately transferred to the neutral gas through elastic and inelastic collisions. This energy drives a large thermal cell and the circulation extends the influence of the arc thousands of kilometers beyond the region of direct heat input. The calculated neutral gas temperature response to electron heating within the arc is small.
    Keywords: GEOPHYSICS
    Type: NASA, Washington Phys. of the Space Environment; p 45-69
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  • 22
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    The composition of the upper atmosphere (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: Miniature mass spectrometers were developed and were carried on sounding rockets to determine the composition of the upper atmosphere. Techniques have been developed that accurately correct for the velocity and spin of the moving vehicle. Above 120 km N2, O2, and Ar appear to be in diffusive equilibrium. Most He concentration measurements show a more rapid decline with altitude than predicted by diffusive equilibrium. Because of the highly reactive nature of atomic oxygen, measurements of this species by mass spectrometry are low by an unknown factor.
    Keywords: GEOPHYSICS
    Type: NASA, Washington Phys. of the Space Environment; p 129-145
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  • 23
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    Hydrology of the Niger River from Nimbus HRIR (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: The seasonal changes in aspect of the Niger River in the Republic of Mali, West Africa, as seen in daytime imagery obtained by the high-resolution infrared radiometer on Nimbus 3 are described. The identification of different plants by their reflectance is shown to provide an ecological map that changes with time. It is concluded that Nimbus imagery provides an integrated view of the entire watershed on a daily basis.
    Keywords: GEOPHYSICS
    Type: Significant Accomplishments in Sci., 1970; p 8-13
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  • 24
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    Air-sea interaction in the Pacific Ocean (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: Daily Tiros and ESSA satellite television nephanalysis over the Pacific Ocean were collected, and monthly cloud charts drawn to study the interaction of tropical oceans with the atmosphere. The data were correlated with climatological data for rainfall and surface temperatures.
    Keywords: GEOPHYSICS
    Type: Significant Accomplishments in Sci., 1970; p 28-31
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  • 25
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    Reginal Geology of Hadley Rille, part F (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: Local geology of Hadley Rille near the landing site of Apollo 15 is described. Orbital photography from the Hasselblad, metric, and panoramic cameras is used to study regional relationships of the rille. The shape of the rille due to various natural causes is examined, along with stratigraphic measurements of mare materials.
    Keywords: GEOPHYSICS
    Type: NASA. Manned Spacecraft Center Apollo 15 Prelim. Sci. Rept.; 5 p
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  • 26
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    Surface disturbances at the Apollo 15 landing site, part E (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: High resolution panoramic photographs taken from 110 km orbits of the command service module show the lunar module structure on the moon as evidenced by reflected light and by the shadow. Before and after photographs of the landing site are presented; the increased brightness or halo is attributed to mare surface materials.
    Keywords: GEOPHYSICS
    Type: NASA. Manned Spacecraft Center Apollo 15 Prelim. Sci. Rept.; 3 p
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  • 27
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    Tides and tsunamis (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: Although tides and tsunamis are both shallow water waves, it does not follow that they are equally amenable to an observational program using an orbiting altimeter on a satellite. A numerical feasibility investigation using a hypothetical satellite orbit, real tide observations, and sequentially increased levels of white noise has been conducted to study the degradation of the tidal harmonic constants caused by adding noise to the tide data. Tsunami waves, possibly a foot high and one hundred miles long, must be measured in individual orbits, thus requiring high relative resolution.
    Keywords: GEOPHYSICS
    Type: Sea Surface Topography from Space, Vol. 2; 30 p
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  • 28
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    Radar augmentation device (1972)
    In:  CASI
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    Publication Date: 2005-11-30
    Description: The radar augmentation device (RAD) serves to increase the radar response of a target body and thus expedite radar acquisition. The design and development of the RAD are discussed with particular emphasis on technical problems that were encountered and solved. Discussions of the mode of operation of the RAD and the ground test history are also included.
    Keywords: COMMUNICATIONS
    Type: NASA. Ames Res. Center 6th Aerospace Mech. Symp.; p 65-72
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  • 29
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    Cracking of the lunar soil (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: Rather than a pattern of cracks in an apparently flat surface, the Apollo 12 photographs suggest an irregular surface that consists of clods or fragments. The impression of flat tiles and crusting, obtained by monoscopic viewing, is an illusion. Instead, the lunar soil deforms and cracks in the same manner as homogeneous isotropic terrestrial soils of moderate bulk density, having a small amount of cohesion.
    Keywords: GEOPHYSICS
    Type: NASA, Washington Analysis of Surveyor 3 Mater. and Phot. Returned by Apollo 12; p 233-235
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  • 30
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    Magnetospheric radio noise (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: Observations, made by the RAE satellite, of earth magnetospheric noise are reported. The observations show radio noise exists at 700 kHz and below. The results are included in graphs.
    Keywords: COMMUNICATIONS
    Type: Significant Accomplishments in Sci., 1970; p 75-80
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  • 31
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    Preliminary geologic map of the region around the candidate Proclus Apollo landing site, part J (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: The Proclus Crater region was mapped to test the value, for photogeologic mapping purposes, of Apollo 15 metric photographs and to estimate the scientific value of the area as a potential landing site. Adjacent frames of the metric photography were overlapped with the base frame to provide stereographic images. Because of the high quality of the photographs, it was found that the geologic units could be more definitely interpreted and dated than those of earlier maps. The photographs tend to confirm the earlier interpretation of the rugged area as composed of bedrock uplifted when the Crisium basin formed. They also suggest that an earlier predominantly volcanic interpretation of the terra in this area might be replaced by an interpretation in which mass wasting and fracturing play the major roles in producing different terrain types. It was concluded that because of apparent lithologic homogeneity, the terra of the Proclus region is an undesirable objective for an extensive manned lunar landing mission.
    Keywords: GEOPHYSICS
    Type: NASA. Manned Spacecraft Center Apollo 15 Prelim. Sci. Rept.; 4 p
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  • 32
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    Magnetospheric boundaries (1972)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: The location of the outer boundary of the geomagnetic field, or magnetopause, and the location of the earth's bow shock have been compiled based on data from the first six IMP satellites.
    Keywords: GEOPHYSICS
    Type: Significant Accomplishments in Sci., 1970; p 81-85
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  • 33
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    Ionospheric profile inversion using oblique-incidence ionograms (1972)
    In:  CASI
    Details
    Publication Date: 2006-03-12
    Description: Some of the elementary methods used in deriving true-height profiles from oblique-incidence ionograms are reviewed. The two principal methods presented are oblique-to-vertical transformation and direct inversion of the oblique-incidence ionogram. Limitations in oblique-incidence inversion due to magnetic-field effects, horizontal gradients, and absolute time delay are discussed.
    Keywords: GEOPHYSICS
    Type: NASA. Ames Res. Center Math. of Profile Inversion; 12 p
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  • 34
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    Automatic N(h,t) profiles of the ionosphere with a digital ionosonde (1972)
    In:  CASI
    Details
    Publication Date: 2006-03-12
    Description: A method is described to accomplish automatic data selection and profile inversion to obtain ionospheric electron density profiles from digitized radio soundings. The profile inversion is based on a well-established formulation by which the optimum radio frequency sounding intervals can be specified from an approximate knowledge of the profile; the expected virtual height coordinates (h) at these frequencies (f) are estimated, and procedures are then used to select h(f) observations nearest the predicted coordinates from a subsequent digital ionogram. From these the next profile is obtained. The process adaptively follows the changing shape and detail of the profile. The procedure requires an average of 15 sec per profile on a standard data processing computer, and can be adapted, with benefit to online real-time use in a digital ionosonde.
    Keywords: GEOPHYSICS
    Type: NASA. Ames Res. Center Math. of Profile Inversion; 11 p
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  • 35
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    The P prime(f) to N(h) inversion problem in ionospheric soundings (1972)
    In:  CASI
    Details
    Publication Date: 2006-03-12
    Description: A general review is given of the inversion techniques used to derive the ionospheric electron density N as a function of altitude h from group path P versus frequency f measurements obtained by vertical incidence ionospheric sounders. The paper discusses the medium under investigation, the experimental techniques used to obtain the P(f) data, the theoretical considerations leading to the integral equation relating P(f) to N(h), and the assumptions made in the inversion process. The lamination inversion technique is then presented, with special attention given to mathematical difficulties arising from discontinuities in the P(f) function, infinities in the integrand, and in some cases unknown integration limits. Methods outlined for minimizing the uncertainties due to discontinuities include the use of redundant information - that is the two distinct P(f) functions available for a given N(h) profile - and the use of models based on statistical data. Mathematical procedures are discussed that increase significantly the efficiency and accuracy of the required numerical integrations. The accuracy of the inversion technique is deduced by comparing the resulting N(h) profile with N(h) data obtained by simultaneous but independent observations.
    Keywords: GEOPHYSICS
    Type: Math. of Profile Inversion; 13 p
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  • 36
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    Error analysis of bent ray radio occultation measurments (1972)
    In:  CASI
    Details
    Publication Date: 2006-03-12
    Description: There are two types of experimental measurement errors of the Doppler data associated with the radio occultation, random and systematic. Random errors are due to thermal noise in the transmission channel, and the phase lock loop, and quantization error in the digital circuitry. These are called noise type errors. The systematic errors are due to geometric uncertainty and equipment phase instability. Considered is the amount of uncertainty, due to random measurement errors, in the refractivity profiles reconstructed by this type of indirect sensing experiment. A class of refractivity profiles is defined which approximately fit the set of measured data. Bounds are placed on the extent of this class of solution profiles. To accomplish this, the sensivity of the reconstructed refractivity profiles to errors in the measured quantity and the statistics of the errors in the measurement are examined.
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    Type: NASA. Ames Res. Center Math. of Profile Inversion; 5 p
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    Statistical retrieval techniques for sounding the meteorological structure of the atmosphere (1972)
    In:  CASI
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    Publication Date: 2006-03-12
    Description: Statistical retrieval methods for remote sounding are reviewed. Methods are given for constraining an essentially incomplete problem by means of the known statistical behavior of the solution. Information content of the observations and the meteorological structure are discussed. Linear versions of maximum probability and minimum variance methods are given in some detail, and extensions to the nonlinear case are described.
    Keywords: GEOPHYSICS
    Type: NASA. Ames Res. Center Math. of Profile Inversion; 10 p
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  • 38
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    A review of some aspects of inferring the ozone profile by inversion of ultraviolet radiance measurements (1972)
    In:  CASI
    Details
    Publication Date: 2006-03-12
    Description: The mathematical inversion of light-scattering observations to obtain the atmospheric ozone profile is discussed in terms of the filtering properties of the physical and mathematical processes for different spatial scales. Within this context, it is shown that the physical process of scattering acts as a low pass filter; which transfers large-scale profile information efficiently to radiance observations but very strongly attenuates small- or fine-scale profile information. To avoid domination of the mathematical inversion by the random error of radiance measurements, an equivalent spatial-scale filtering in the inversion procedure is essential. The available evidence suggests that mathematical inversion to obtain the low level ozone profile below 25 to 30 km is either inferior to or no better than the statistical estimation of the profile using total ozone as predictor. However, inversion profiles for high level ozone above 25 to 30 km appear to have moderately good accuracy.
    Keywords: GEOPHYSICS
    Type: NASA. Ames Res. Center Math. of Profile Inversion; 24 p
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  • 39
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    Some special cases of the electromagnetic inverse problem (1972)
    In:  CASI
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    Publication Date: 2006-03-12
    Description: A review of exact techniques for determining the surface of a three-dimensional perfectly conducting body is given, followed by some new results on the uniqueness question concerning the number of measurements that may be required to explicitly determine the surface of the body. It is then shown that the inhomogeneous but spherically symmetric dielectric electromagnetic case is reducible to a scalar inverse problem that can be treated by known techniques.
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    Type: NASA. Ames Res. Center Math. of Profile Inversion; 11 p
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  • 40
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    A review of nonstatistical techniques for the estimation of vertical atmospheric structure from remote infrared measurements (1972)
    In:  CASI
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    Publication Date: 2006-03-12
    Description: Mathematical techniques used in atmospheric profile inversion are reviewed, with the discussion limited to methods that do not require extensive information on the statistical properties of the profiles. The basic problem of the calculation of vertical profiles from noise contaminated infrared spectral measurements is examined. Three specific examples of methods of solution are given: the iterative minimum estimation method, a second linear iterative method, and the algorithm of Chahine. Satellite data are used in an empirical comparison of the methods. Several factors are considered, including the stability of solutions, convergence behavior of the iterative methods, and dependence of the solutions on the first guess, a factor that is particularly important in the treatment of data from other planets.
    Keywords: GEOPHYSICS
    Type: Math. of Profile Inversion; 14 p
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  • 41
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    Spacecraft ion beam noise effects (1972)
    In:  CASI
    Details
    Publication Date: 2006-02-22
    Description: An estimate of the antenna noise temperature and the uplink signal-to-noise ratio has been made for Bremsstrahlung radiation emitted by a spacecraft ion beam; a worst-case situation in which the spacecraft antenna is located in the exit plane of the ion beam and directed at varying angles into the ion beam is assumed. Numerical results of the antenna noise temperature versus antenna pointing angle are given for a typical set of ion beam and antenna pattern parameters. The uplink signal-to-noise ratio due to the ion beam noise alone is given in terms of a critical range in AU at which a typical ranging transmission is received with S/N = 0 db. The effects of the ion beam divergence angle and antenna distance on the ion beam are also presented. Results of the study show typical increases in the antenna noise temperature of about 0.2 K and critical ranges of the order of 3-5 AU. An ion engine thus generally introduces an undetectable level of noise into a spacecraft receiver.
    Keywords: COMMUNICATIONS
    Type: JPL Quart. Tech. Rev., Vol. 2, No. 2; p 61-71
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  • 42
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    Interplex: An analysis of optimized power allocations for two and three channel PSK/PM telecommunications systems (1972)
    In:  CASI
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    Publication Date: 2006-02-22
    Description: Optimal design concepts are presented for two- and three-channel telemetry modes in the context of the Mariner Venus-Mercury 1973 mission and the usefulness of interplex modulation techniques is discussed. These ideas are applied as an example to one Mariner Venus-Mercury 1973 telemetry mode to demonstrate that interplex can reduce the required total average power by more than 2 dB in some cases.
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    Type: JPL Quarterly Tech. Rev., Vol. 2, No. 1; p 143-151
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  • 43
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    Analysis of the failure of a polyester peripheral drive belt on the Mariner Mars 1971 flight tape recorder (1972)
    In:  CASI
    Details
    Publication Date: 2006-02-22
    Description: A peripheral drive belt on the Mariner Mars 1971 tape recorder failed when a thin longitudinal strip separated off one edge. Analysis showed that the most probable cause of failure occurred from flexural fatigue initiating in mechanically weak locations which are introduced into the belt during fabrication. Methyl ethyl ketone, which is employed as a cleaning solvent during fabrication, was found to cause permanent reduction in engineering properties of polyester and could have contributed to the reduction of the fatigue resistance. Fatigue properties of the polyester drive belt are reviewed for the operating condition, as well as the sensitivity of polyester to cleaning solvents and the origin of mechanically weak locations.
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    Type: JPL Quarterly Tech. Rev., Vol. 2, No. 1; p 82-99
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  • 44
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    Studies on the frictional behavior of magnetic recording tapes (1972)
    In:  CASI
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    Publication Date: 2006-02-22
    Description: Methods were developed for measuring frictional forces acting on a magnetic tape in motion or at rest, as well as the extent of stick slip. The effects of factors such as temperature, humidity, kind of gaseous atmosphere, and tape speed on the frictional interaction between various tapes and heads were investigated. Results were instrumental in the selection of a tape for the Mariner Mars 1971 spacecraft. Studies are reported on the stick slip behavior of tapes and the performance of a metallic tape, compared with the usual plastic tapes.
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    Type: JPL Quarterly Tech. Rev., Vol. 2, No. 1.; p 100-106
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  • 45
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    Apparatus for investigation of the amplitude frequency response of the ionospheric scattering channel (1972)
    In:  CASI
    Details
    Publication Date: 2006-04-26
    Description: Equipment for studying the amplitude frequency response of the ionospheric scattering channel is described, having multipath signal propagation. Experimental results are reported, including nonuniformity in the channel's amplitude frequency response.
    Keywords: GEOPHYSICS
    Type: Morphology of the Quiet and Disturbed Ionosphere; p 39-45
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  • 46
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    Parameters of small scale ionization inhomogeneities in the F region of the ionosphere (1972)
    In:  CASI
    Details
    Publication Date: 2006-04-26
    Description: The results of the parameters of small-scale ionization inhomogeneities study of the ionosphere's F-region for October-November 1965 and January-February 1966 are presented. It is shown that the most probable values of the inhomogeneity parameters are as follows: degree of anisotropy 1.4-2; vertical dimension 200-400 m; horizontal dimensions along major and minor axes 400-1000 and 200-600 m, respectively; rate of chaotic motions 30-60 m/sec; lifetime 6-9 sec.
    Keywords: GEOPHYSICS
    Type: Morphology of the Quiet and Disturbed Ionosphere; p 23-29
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  • 47
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    Results from simultaneous radar-television observations (1972)
    In:  CASI
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    Publication Date: 2006-04-24
    Description: The results of the reduction of simultaneous observations of 29 meteors are presented in tabular form. Fragmentation of the observations is discussed along with the 50 meteors not yet reduced.
    Keywords: COMMUNICATIONS
    Type: Meteor Res. Program; p 83-99
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  • 48
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    Analysis procedure for television observations and simultaneous observations (1972)
    In:  CASI
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    Publication Date: 2006-04-24
    Description: The procedures used in the analysis of television and simultaneous observations are described. Starting with the right ascension and declination of the meteor, the celestrial triangle formed by Sidell and the meteor is solved, and the epochs of the beginning and end of the meteor observation as recorded on the video tape are determined.
    Keywords: COMMUNICATIONS
    Type: Meteor Res. Program; p 69-76
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  • 49
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    Simultaneous observations by television camera and radar (1972)
    In:  CASI
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    Publication Date: 2006-04-24
    Description: The original image-orthicon equipment used for simultaneous radar and optical observations is described. The adaptations made to enhance its usefulness for meteor observations, and the specialized calibration and photometric procedures developed for this purpose are also described. Some brief comments concerning the use of the secondary electron conduction vidicon are included.
    Keywords: COMMUNICATIONS
    Type: Meteor Res. Program; p 29-36
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  • 50
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    Receiving antenna installation for ionospheric scattering links (1972)
    In:  CASI
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    Publication Date: 2006-04-26
    Description: Smearing of the scattered-energy flux density over a range of angles of arrival permits the use of a receiving-end antenna with a height lower than theoretical.
    Keywords: GEOPHYSICS
    Type: Morphology of the Quiet and Disturbed Ionosphere; p 65-68
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  • 51
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    The ionosphere above Alma Ata during a solar eclipse (1972)
    In:  CASI
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    Publication Date: 2006-04-26
    Description: The eclipse effect was manifested during the second phase: the ionization of the F1- and F2-layers decreased and the minimum effective heights of E and F2 increased due to recombination processes. The manner in which electron density is distributed over the levels was ascertained from analysis of N(t) curves.
    Keywords: GEOPHYSICS
    Type: Morphology of the Quiet and Disturbed Ionosphere; p 35-38
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  • 52
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    Radioastronomical measurement of absorption (1972)
    In:  CASI
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    Publication Date: 2006-04-26
    Description: Diurnal and seasonal absorption curves measured by a radio astronomical method at Alma-Ata during the IQSY (1964-1965) are submitted. The apparatus is described. The dependence of absorption on solar flares is also indicated.
    Keywords: GEOPHYSICS
    Type: Morphology of the Quiet and Disturbed Ionosphere; p 30-34
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  • 53
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    The state of the ionosphere above Alma Ata (1972)
    In:  CASI
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    Publication Date: 2006-04-26
    Description: The basic patterns are described in the behavior of critical frequencies and minimum effective heights of the ionosphere's reflecting E, F1, and F2 layers, according to ionospheric recorder measurements from 1943 to 1967. The variations of critical frequencies and virtual heights are compared with the relative sunspot numbers and the flux of the sun's radio emission at 10.7 cm.
    Keywords: GEOPHYSICS
    Type: Morphology of the Quiet and Disturbed Ionosphere; p 1-6
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  • 54
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    On the selection of a vertical base in the ionosphere (1972)
    In:  CASI
    Details
    Publication Date: 2006-04-26
    Description: The problem of selecting a vertical base in the ionosphere that permits registration of vertical motions of small-scale ionization inhomogeneities of the ionosphere's F-region is discussed. The accuracy of calculation of the vertical drift-velocity component is estimated.
    Keywords: GEOPHYSICS
    Type: Morphology of the Quiet and Disturbed Ionosphere; p 7-12
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  • 55
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    Results of measurement of radio wave absorption in the ionosphere by the AI method (1972)
    In:  CASI
    Details
    Publication Date: 2006-04-26
    Description: Median noon absorption values for each month from 1964 through 1967, the diurnal variations of absorption on the regular world days, and the seasonal variations of absorption are given. The dependence of the absorption coefficient on sunspot number is analyzed.
    Keywords: COMMUNICATIONS
    Type: Morphology of the Quiet and Disturbed Ionosphere; p 99-112
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  • 56
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    A method of investigating the phase response characteristic of the ionospheric scattering communications channel (1972)
    In:  CASI
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    Publication Date: 2006-04-26
    Description: A method is proposed for measuring the phase difference fluctuations between vibrations at different frequencies that result from scattering properties of the medium. The measurement equipment is described, along with an ideal communication channel.
    Keywords: GEOPHYSICS
    Type: Morphology of the Quiet and Disturbed Ionosphere; p 47-54
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  • 57
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    Radio wave propagation at frequencies exceeding MUF-F2 in the short wave band (1972)
    In:  CASI
    Details
    Publication Date: 2006-04-26
    Description: The results of measurements of field strength and signal/noise ratio on experimental ionospheric-scattering short wave radio links are presented. It is shown that the seasonal and diurnal variations of field strength are determined by features of solar and meteoric activity. The role of the sporadic E-layer in propagation of short radio waves at frequencies exceeding MUF-F2 is noted.
    Keywords: GEOPHYSICS
    Type: Morphology of the Quiet and Disturbed Ionosphere; p 55-59
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  • 58
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    Ionospheric magnetic phenomena associated with proton flares (1972)
    In:  CASI
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    Publication Date: 2006-04-26
    Description: The state of the ionosphere above stations in Kazakhstan is examined in connection with the proton flares of 7 July, 28 August, and 2 September 1966. Universal time is used. It is established that a proton flare causes increased radio absorption (the ionization of the D-region is enhanced, and the minimum reflected frequencies decrease). Magnetic storms and ionospheric disturbances are observed on the earth one-and-a-half to two days after some proton flares.
    Keywords: GEOPHYSICS
    Type: Morphology of the Quiet and Disturbed Ionosphere; p 17-22
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  • 59
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    Influence of vertical drift of small scale ionization inhomogeneities on the diurnal variation of f0F2 (1972)
    In:  CASI
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    Publication Date: 2006-04-26
    Description: The diurnal variations of the critical frequencies of the ionospheric F2 region may be influenced substantially by the 12-hour component of the vertical drift of small-scale ionization inhomogeneities. The appearance of the forenoon maximum of F2 and the evening ionization maximum are examined.
    Keywords: GEOPHYSICS
    Type: Morphology of the Quiet and Disturbed Ionosphere; p 13-16
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  • 60
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    Estimates of the electric fields in the lower ionosphere above the magnetic equator (1972)
    In:  CASI
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    Publication Date: 2006-04-26
    Description: The electric fields at the solar activity minimum on the magnetic equator are evaluated based on data from rocket studies of the vertical profiles of the ionospheric-current magnetic fields and electron concentration. The electric field strength is 1-4 X 100 CGSM units. In addition, the electric field has altitude and time distributions. Its maximum is observed at a height of 110 km, and at 90 and 140 km, it is smaller by a factor of 3-4 than at the 110-km height. The maximum values are registered around noon.
    Keywords: GEOPHYSICS
    Type: Morphology of the Quiet and Disturbed Ionosphere; p 82-89
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    On the possibility of explaining features of the latitude variations of Sq(H) and Sq(Z) in the equatorial region by electrical modelling (1972)
    In:  CASI
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    Publication Date: 2006-04-26
    Description: Curves of H (the horizontal component) and Z (the vertical component) of the magnetic field from a strip with an assigned current-density distribution compiled from the results of electrical modelling are calculated. The calculated curves are compared qualitatively with latitude curves obtained from ground magnetic observatory data. It is shown that the forms of the theoretical H and Z and the experimental latitude variations are qualitatively similar.
    Keywords: GEOPHYSICS
    Type: Morphology of the Quiet and Disturbed Ionosphere; p 90-94
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  • 62
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    Occupancy of the radio frequency spectrum in the 16-23 MHz band (1972)
    In:  CASI
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    Publication Date: 2006-04-26
    Description: Measurement results are presented for actual utilization of the short wave frequency band, obtained by continuous registration of the number of radio stations in the 16-23 MHz band over an annual cycle (1965). It is shown that there is a relation between the number of radio stations and the variations of MUF-F2. During years of minimum solar activity and at night, segments free of radio stations operating by normal reflection, can be selected in the 18-23-MHz band for ionospheric-scattering links.
    Keywords: GEOPHYSICS
    Type: Morphology of the Quiet and Disturbed Ionosphere; p 60-64
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    Analysis procedure for radar observations (1972)
    In:  CASI
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    Publication Date: 2006-04-24
    Description: Based on the assumption that the ionized column left behind a moving meteroroid is underdense, it is shown that radar observations of the column yield resonable aproximations to the meteoriod's speed and trajectory. The principles and procedures for finding a meteor's position and vector velocity from the observed data are also presented.
    Keywords: COMMUNICATIONS
    Type: Meteor Res. Program; p 51-68
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  • 64
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    Antenna calibration at Havana (1972)
    In:  CASI
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    Publication Date: 2006-04-24
    Description: The procedures for calibrating the antenna patterns of the Havana radar system are described along with the reduction of the measurements made using a dipole towed behind an airplane. The power-gain pattern for the north, south, and joint troughs of sites 3 and 4 are plotted.
    Keywords: COMMUNICATIONS
    Type: Meteor Res. Program; p 37-50
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    Description of eight station radar near Havana, Illinois (1972)
    In:  CASI
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    Publication Date: 2006-04-24
    Description: A general description is given of the eight-station system at Havana which incorporated high-gain antennas and a powerful transmitter to reach faint meteors on the order of magnitude of plus 12. The station location, principle of system design, systems connections, transmitter, receivers, logics, range measurement, and recording are described.
    Keywords: COMMUNICATIONS
    Type: Meteor Res. Program; p 19-27
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  • 66
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    Acoustic radar sounding of the lower atmosphere (1972)
    In:  CASI
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    Publication Date: 2006-03-12
    Description: Acoustic radar sounding techniques were used to measure the wind velocity and direction in the first 300 m of the atmosphere. Angle-of-arrival and Doppler techniques were developed to obtain two independent measurements of the wind field. These techniques and preliminary experimental results are described briefly.
    Keywords: GEOPHYSICS
    Type: NASA. Ames Res. Center Math. of Profile Inversion; 11 p
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  • 67
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    Statistical versus nonstatistical temperature inversion methods (1972)
    In:  CASI
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    Publication Date: 2006-03-12
    Description: Vertical temperature profiles are derived from radiation measurements by inverting the integral equation of radiative transfer. Because of the nonuniqueness of the solution, the particular temperature profile obtained depends on the numerical inversion technique used and the type of auxiliary information incorporated in the solution. The choice of an inversion algorithm depends on many factors; including the speed and size of computer, the availability of representative statistics, and the accuracy of initial data. Results are presented for a numerical study comparing two contrasting inversion methods: the statistical-matrix inversion method and the nonstatistical-iterative method. These were found to be the most applicable to the problem of determining atmospheric temperature profiles. Tradeoffs between the two methods are discussed.
    Keywords: GEOPHYSICS
    Type: NASA. Ames Res. Center Math. of Profile Inversion; 7 p
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  • 68
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    The inversion of VLF-LF sounder data to obtain D-region electron-density distributions (1972)
    In:  CASI
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    Publication Date: 2006-03-12
    Description: The direct problem is to compute reflection coefficients for an assumed electron-density profile, using a full-wave solution. The inverse problem is treated numerically, using derivatives of the reflection matrix with respect to model parameters. A technique for the rapid computation of the derivatives is described. An algorithm for determining resolution in the profile is discussed.
    Keywords: GEOPHYSICS
    Type: NASA. Ames Res. Center Math. of Profile Inversion; 7 p
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    The calculation of electron density profiles from topside ionograms: Method and applications (1972)
    In:  CASI
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    Publication Date: 2006-03-12
    Description: A method for converting topside sounder ionograms into topside electron density profiles is discussed. The lamination method used is modified to take into account the variation of electron density and magnetic field within each lamination. Also included is a change of variable to produce a finite integrand of the integral involved, an iteration scheme that permits convergence on an initially unknown density, a second iteration scheme to overcome the problem of an uncertainty in the electron density at the satellite, and a modification to compensate for the changing satellite altitude over the duration of the sounding. Two applications of the technique are discussed: field-aligned traces for computing field-aligned profiles and computer-aided systems for scaling ionograms.
    Keywords: GEOPHYSICS
    Type: NASA. Ames Res. Center Math. of Profile Inversion; 11 p
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    An occultation satellite system for determining pressure levels in the atmosphere (1972)
    In:  CASI
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    Publication Date: 2006-03-12
    Description: An operational two-satellite microwave occultation system will establish a pressure reference level to be used in fixing the temperature-pressure profile generated by the SIRS infrared sensor as a function of altitude. In the final error analysis, simulated data for the SIRS sensor were used to test the performance of the occultation system. The results of this analysis indicate that the occultation system is capable of measuring the altitude of the 300-mb level to within 24 mrms, given a maximum error of 2 K in the input temperature profile. The effects of water vapor can be corrected by suitable climatological profiles, and improvements in the accuracy of the SIRS instrument should yield additional improvements in the performance of the occultation system.
    Keywords: GEOPHYSICS
    Type: NASA. Ames Res. Center Math. of Profile Inversion; 13 p
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    Fine structure of the lower atmosphere as seen by high resolution radar (1972)
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    Publication Date: 2006-03-12
    Description: A ground-based vertically pointing FM-CW radar is described that permits remote probing of the refractive index structure in the troposphere. The radar has the characteristics of extremely high sensitivity, ultrahigh range resolution, and close minimum detection range without clutter. The sounder routinely detects layer structures in the lower troposphere. These layers are always associated with gradients in the vertical refractive index profile, and are frequently very thin, approaching the resolution of the radar (1 m). Very often they are perturbed by wave motions. Examples of various wave patterns are presented, and an explanation is given for organized substructures frequently superimposed on larger scale wave motions.
    Keywords: GEOPHYSICS
    Type: NASA. Ames Res. Center Math. of Profile Inversion; 8 p
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    The mathematical-physical problem of P prime(f) to N(h) inversion for anisotropic media (1972)
    In:  CASI
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    Publication Date: 2006-03-12
    Description: The requirements for a numerical inversion method to calculate electron density profiles from ionograms are discussed. A systematic investigation about the independence of the two magnetoionic components shows that the extent to which the range of ambiguity can be reduced depends mainly on the magnetic latitude. Error estimates and first-order corrections for less elaborate methods are included.
    Keywords: GEOPHYSICS
    Type: NASA. Ames Res. Center Math. of Profile Inversion; 13 p
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    Numerical methods for reduction of topside ionograms (1972)
    In:  CASI
    Details
    Publication Date: 2006-03-12
    Description: Several alternative methods for solving the group height equation are presented. Three of these are now in operation at Ames Research Center and use data contained in a single ionogram trace. From the data an electron density profile N(h) is computed. If the ionogram also exhibits other traces, reverse ionogram traces are computed, using the N(h) profile, for comparison with the redundant data. When agreement is poor, the initial data trace is reinterpreted, another N(h) profile computed, and the reverse traces generated once again. This process is repeated until a desired degree of consistency is achieved. To reduce the necessity for human intervention and eliminate decision making required in conjunction with the preceding methods, a method is proposed that accepts as input, all data from a single ionogram. In general, no electron density function will satisfy these data exactly, but a best N(h) profile can be computed. Finally, a method is described that eliminates the need to assume that the ionosphere is spherically stratified. Horizontal gradients in electron density are detected and accounted for by processing several ionograms from the same satellite pass simultaneously. This idea is derived as an extension of one of the basic methods.
    Keywords: GEOPHYSICS
    Type: NASA. Ames Res. Center Math. of Profile Inversion; 10 p
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    Precision signal power measurement (1972)
    In:  CASI
    Details
    Publication Date: 2006-02-22
    Description: Accurate estimation of signal power is an important Deep Space Network (DSN) consideration. Ultimately, spacecraft power and weight is saved if no reserve transmitter power is needed to compensate for inaccurate measurements. Spectral measurement of the received signal has proved to be an effective method of estimating signal power over a wide dynamic range. Furthermore, on-line spectral measurements provide an important diagnostic tool for examining spacecraft anomalies. Prototype equipment installed at a 64-m-diameter antenna site has been successfully used to make measurements of carrier power and sideband symmetry of telemetry signals received from the Mariner Mars 1971 spacecraft.
    Keywords: COMMUNICATIONS
    Type: JPL Quart. Tech. Rev., Vol. 2, No. 2; p 18-24
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  • 75
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    The shadow band phenomenon. (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Observation of shadow bands during the solar eclipse of Mar. 7, 1970. Data were gathered by recording onto magnetic tape of the output from six collimated photocells whose spectral responses ranged from the ultraviolet to the infrared, and by visual and mechanical measurement of the orientation and motion of the bands. The recorded data were later processed using the output from a frequency spectrum analyzer. Most of the energy of the shadow bands ranges between 1 and 25 Hz, and appears not unlike plots of scintillation spectra. The onset, amplitude, and duration of the shadow bands seem to be spectrally related to the limb darkening of the sun's photosphere. Other results of the experiment conclusively indicate that the shadow band phenomenon is a manifestation of atmospheric turbulence in the form of air packets of different density from that of their environment (density schlieren), made visible by the light from the crescent sun.
    Keywords: GEOPHYSICS
    Type: Journal of Atmospheric and Terrestrial Physics; 34; Apr. 197
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  • 76
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    Mode coupling in partial reflections from the ionosphere at vertical incidence. (1972)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The effect of mode coupling has been calculated for radio waves partially reflected from the lower ionosphere at vertical incidence. Calculations were made for parameters appropriate to the partial reflection experiments (Belrose, 1970). The four reflection coefficients (two direct and two coupled) are calculated for a plane discontinuity using a matrix perturbation analysis. The ratios of coupled to direct reflection coefficients are calculated for a general one-dimensional reflecting layer using the coupled equations of Clemmow and Heading (1954). At the highest electron density considered, 10,000 per cu cm, about 10% of the reflected extraordinary wave amplitude might be due to coupling from the incident ordinary wave. The effect is smaller at lower electron density.
    Keywords: COMMUNICATIONS
    Type: Radio Science; 7; Apr. 197
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  • 77
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    Atmospheric density variations at 140 kilometers deduced from precise satellite radar tracking data. (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Discussion of the technique of evaluating density values from precise radar-tracking data of satellites in the altitude region from 130 to 140 km. Inclinations of these satellites were between 106 and 112 deg. A detailed examination of all elements of the density-reduction techniques was conducted, and consideration was given to recent advances in geodesy, drag-coefficient modeling, and orbit-determination techniques. Ten days of high-resolution density data deduced from orbital decay of each of three satellites are presented. Three types of density variations at 140 km are discernible in these data: periodic daily density variations with a density amplitude of about 10%; density increases of up to 35% associated with enhanced geomagnetic activity during which the planetary geomagnetic index Kp reached a value of 8 units; and an observed semiannual variation of about 20%, which indicates a total semiannual variation of 35 to 40%.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 77; Apr. 1
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  • 78
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    On the relative need for satellite remote soundings and rocket soundings of the upper atmosphere. (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A review of engineering and research data requirements for altitudes 30-100 km is made, indicating a variety of concrete data applications above 30 km (10 mb). The required data have in large measure been provided from meteorological rocket soundings, of which 18,000 have been taken, at considerable cost, since 1959. Remote vertical soundings based on satellite infrared radiation measurements have been obtained since 1969 with considerable success to an altitude of 25 km (30 mb). From developmental work in progress, it is expected that reliable temperature soundings may be obtained to 40-45 km. A discussion of the overall reliability and utility of the satellite data leads to several conclusions regarding the continuing need for rocket soundings.
    Keywords: GEOPHYSICS
    Type: American Meteorological Society; vol. 53
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  • 79
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    Convergence of oscillator spectral estimators for counted-frequency measurements. (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A common intermediary connecting frequency-noise calibration or testing of an oscillator to useful applications is the spectral density of the frequency-deviating process. In attempting to turn test data into predicts of performance characteristics, one is naturally led to estimation of statistical values by sample-mean and sample-variance techniques. However, sample means and sample variances themselves are statistical quantities that do not necessarily converge (in the mean-square sense) to actual ensemble-average means and variances, except perhaps for excessively large sample sizes. This is especially true for the flicker noise component of oscillators. This article shows, for the various types of noises found in oscillators, how sample averages converge (or do not converge) to their statistical counterparts. The convergence rate is shown to be the same for all oscillators of a given spectral type.
    Keywords: COMMUNICATIONS
    Type: IEEE Transactions on Communications; COM-20; Apr. 197
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  • 80
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    Oceanographic applications of color-enhanced satellite imageries. (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Black and white infrared imageries obtained from satellites over the oceans were transformed into color presentations. Investigations in different regions (Persian Gulf, Arabian Coast, Somali Coast and the Northwest Coast of Australia) revealed that temperature gradients and temperature differences of two degrees Celsius can be displayed by the color process from the imageries. This data display can be used for a rapid analysis of information obtained with an APT station.
    Keywords: GEOPHYSICS
    Type: Remote Sensing of Environment; 2; Feb. 197
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  • 81
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    An observation of the Gulf Stream surface front structure by ship, aircraft, and satellite. (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Evaluation of observations of surface temperature and salinity along the western edge of the Gulf Stream made from a ship and of concurrent temperature observations obtained by instrumented aircraft at six altitudes. The major feature along a five-kilometer line normal to the Stream's edge is a temperature gradient of about 0.75 C/kilometer within which are embedded two abrupt temperature increases of about 1.5 C. Temperature variations were compensated by salinity variations, yielding nearly constant density through the frontal zone; a sharp lateral current shear was associated with the thermohaline mixing region between the steps. The attenuation of surface temperature measured by the airborne radiometer was compared with a theoretical model. The analysis supports the view that a two-part correction technique is required: one part for bulk-skin temperature differences, and another for atmospheric attenuation of sea surface emission due to the mass and temperature of interfering gases.
    Keywords: GEOPHYSICS
    Type: Remote Sensing of Environment; 2; Feb. 197
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  • 82
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    Rocket observations of sporadic-E layers. (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The characteristics of midlatitude sporadic-E layers are observed using rocket payloads incorporating a probe and a propagation experiment. Layers below 120 km show evidence of preferred altitudes. The slopes of layers are within 1 deg of horizontal. The horizontal dimensions are deduced to be several hundred kilometers. Individual profiles of daytime layers show a range of shapes ranging from triangular to rectangular. The plasma frequency derived from the peak electron density in the layer is found to agree with the blanketing frequency given by the local ionosphere sounder.
    Keywords: GEOPHYSICS
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  • 83
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    Quantitative relationship between reflectance and transpiration of phreatophytes, Gila River test site (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The use of IR aerial photographs for determining the dynamic characteristics of evapotranspiration at the Gila River Test Site is discussed. Evapotranspiration was measured as a function of plant volume, surface conditions, soil moisture storage, and ground water levels.
    Keywords: GEOPHYSICS
    Type: NASA. Manned Spacecraft Center 4th Ann. Earth Resources Program Rev., Vol. 3; 9 p
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  • 84
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    Discrimination of fluoride and phosphate contamination in central Florida for analyses of environmental effects (1972)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: A study was made of the spatial registration of fluoride and phosphate pollution parameters in central Florida by utilizing remote sensing techniques. Multispectral remote sensing data were collected over the area and processed to produce multispectral recognition maps. These processed data were used to map land areas and waters containing concentrations of fluoride and phosphate. Maps showing distribution of affected and unaffected vegetation were produced. In addition, the multispectral data were processed by single band radiometric slicing to produce radiometric maps used to delineate areas of high ultraviolet radiance, which indicates high fluoride concentrations. The multispectral parameter maps and radiometric maps in combination showed distinctive patterns, which are correlated with areas known to be affected by fluoride and phosphate contamination. These remote sensing techniques have the potential for regional use to assess the environmental impact of fluoride and phosphate wastes in central Florida.
    Keywords: GEOPHYSICS
    Type: NASA. Manned Spacecraft Center 4th Ann. Earth Resources Program Rev., Vol. 3; 12 p
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  • 85
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    An automated map and model of land use in the Phoenix quadrangle (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Efforts to develop an automated system, from ERTS data, for producing computer models and computer maps of land use and other environmental factors for the Phoenix quadrangle are outlined.
    Keywords: GEOPHYSICS
    Type: NASA. Manned Spacecraft Center 4th Ann. Earth Resources Program Rev., Vol. 3; 19 p
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  • 86
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    The geography and human cultural resources working group of the EROS program (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The functions, activities, and objectives of the Geography and Human-Cultural Resources Working Group of the EROS program are outlined. The Group's primary function is to coordinate remote sensing experiments of physical scientists and the needs of socioeconomic and culturally orientated planners, policy makers, administrators, and other user groups. Other functions of the Group include land use analysis, resource mapping, and development of an operational automatic information system receptive to land use and environmental data.
    Keywords: GEOPHYSICS
    Type: NASA. Manned Spacecraft Center 4th Ann. Earth Resources Program Rev., Vol. 3; 4 p
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  • 87
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    Automatic thematic mapping in the EROS program (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A specified approach to the automatic extraction and catographic presentation of thematic data contained in multispectral photographic images is presented. Experimental efforts were directed toward the mapping of open waters, snow and ice, infrared reflective vegetation, and massed works of man. The system must also be able to process data from a wide variety of sources.
    Keywords: GEOPHYSICS
    Type: NASA. Manned Spacecraft Center 4th Ann. Earth Resources Program Rev., Vol. 3; 13 p
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  • 88
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    Earth resources cartography program (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Progress is reported on efforts to develop techniques of using space vehicle and high altitude aircraft imagery in cartography projects. Major efforts were made to develop an operational system for isolating specified themes from the imagery.
    Keywords: GEOPHYSICS
    Type: NASA. Manned Spacecraft Center 4th Ann. Earth Resources Program Rev., Vol. 3; 8 p
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  • 89
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    Remote sensing on Indian and public lands (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The use of remote sensing techniques by the Bureaus of Indian Affairs and Land Management in planning resource problems, making decisions, writing environmental impact statements, and monitoring their respective programs is investigated. For Indian affairs, data cover the Papago, Fort Apache, San Carlos, and South Dakota Reservations. For the Land Management Office, data cover cadastral surveys, California desert study, range watersheds, and efforts to establish a natural resources information system.
    Keywords: GEOPHYSICS
    Type: NASA. Manned Spacecraft Center 4th Ann. Earth Resources Program Rev., Vol. 3; 7 p
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  • 90
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    Mapping of terrain by computer clustering techniques using multispectral scanner data and using color aerial film (1972)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Two clustering techniques were used for terrain mapping by computer of test sites in Yellowstone National Park. One test was made with multispectral scanner data using a composite technique which consists of (1) a strictly sequential statistical clustering which is a sequential variance analysis, and (2) a generalized K-means clustering. In this composite technique, the output of (1) is a first approximation of the cluster centers. This is the input to (2) which consists of steps to improve the determination of cluster centers by iterative procedures. Another test was made using the three emulsion layers of color-infrared aerial film as a three-band spectrometer. Relative film densities were analyzed using a simple clustering technique in three-color space. Important advantages of the clustering technique over conventional supervised computer programs are (1) human intervention, preparation time, and manipulation of data are reduced, (2) the computer map, gives unbiased indication of where best to select the reference ground control data, (3) use of easy to obtain inexpensive film, and (4) the geometric distortions can be easily rectified by simple standard photogrammetric techniques.
    Keywords: GEOPHYSICS
    Type: 4th Ann. Earth Resources Program Rev., Vol. 3; 30 p
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  • 91
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    High-sensitivity receiver for infrared laser communications. (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Description of a high-sensitivity wide-bandwidth 10.6-micron heterodyne receiver for space and ground operational use. The receiver includes a cooled HgCdTe infrared mixer diode, a conical scanner for spatial tracking, an acquisition channel for spatial search and station alignment, and an automatic frequency-control channel to maintain a fixed laser frequency offset. The infrared mixer is designed to provide nearly quantum-noise-limited operation over an extended range of mixer temperature, bias voltage, and intermediate frequency. The resultant experimental receiver has a measured noise equivalent power of less than 10 to the minus 19th W/Hz over the 15- to 40-MHz i.f. band for mixer temperatures from 85 to 115 K, and less than 2 x 10 to the minus 19th W/Hz up to 140 K. Mixer 3-dB cutoff frequencies as high as 420 MHz were measured at a mixer temperature of 125 K. An analysis and engineering equations are given for receiver noise components, noise equivalent power, available mixer conversion gain, mixer transducer gain, and quantum-noise factor in terms of such factors as mixer parameters, quantum efficiency, mixer temperature, dynamic conductance, bias voltage, local oscillator power, and i.f. amplifier characteristics.
    Keywords: COMMUNICATIONS
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  • 92
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    Imp 5 magnetic-field measurements in the high-latitude outer magnetosphere near the noon meridian. (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Results of Imp 5 magnetic-field measurements at geomagnetic latitudes up to 75 deg and at distances beyond six earth radii, revealing the permanent existence of a broad depressed field region centered on the polar or dayside cusp. Field strengths at seven earth radii on cusp field lines that connect to the earth are typically only 50 to 70% of that of an undistorted dipole field. The transition region between the magnetosheath and the point where the fields are clearly of dipolar origin is characterized by large-amplitude fluctuations and the lack of a clear magnetopause boundary. Magnetic-field perturbations are observed in the cusp region with magnitudes up to 45 gamma and in directions that are approximately perpendicular to the average field. These perturbations are suggestive of field-aligned currents, and their magnitudes are consistent with the low-altitude measurements obtained on polar-orbiting spacecraft.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 77; Feb. 1
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    Internal structure of the geomagnetic neutral sheet. (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A study of the internal structure of the neutral sheet in the geomagnetic tail has been made from data obtained by the NASA-GSFC magnetic-field experiment on the Explorer 34 spacecraft during its tail passage in the first half of 1968. The data used in the analysis are individual measurements of the vector magnetic field at 2.56-sec intervals. The experimental results consist of statistical studies of relevant properties of the magnetic field as a function of field magnitude. The results do not support nearly one-dimensional field models with characteristic lengths for field variation parallel to the neutral sheet much larger than the neutral-sheet width. The principal conclusion from the data points toward consistency with a quasi-periodic (possibly turbulent) structure with a tendency to formation of magnetic loops as one might expect from stability studies.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 77; Jan. 1
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    Airborne optical detection of oil on water. (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Airborne measurements were made over controlled oil-spill test sites to evaluate various techniques, utilizing reflected sunlight, for detecting oil on water. The results of these measurements show that (1) maximum contrast between oil and water is in the UV and red portions of the spectrum; (2) minimum contrast is in the blue-green; (3) differential polarization appears to be a very promising technique; (4) no characteristic absorption bands, which would permit one oil to be distinguished from another, were discovered in the spectral regions measured; (5) sky conditions greatly influence the contrast between oil and water; and (6) highest contrast was achieved under overcast sky conditions.
    Keywords: GEOPHYSICS
    Type: Applied Optics; 11; Jan. 197
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  • 95
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    Requirements for laser radar detection of a barium ion cloud at five earth radii. (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The requirements for a tuned laser radar capable of detecting and ranging a high altitude barium ion cloud release are discussed. A high energy pulsed dye laser tuned to the 455.4 nm Ba II resonance line is considered as the transmitter. Photon counting detection is employed and the resultant signal is integrated over a number of successive laser firings. The solar induced radiance of the cloud is the major background noise source. Detection and ranging may be achieved with signal-to-noise ratios of the order of unity using currently available equipment. This technique has the potential of improved resolution as compared to photographic measurements previously made.
    Keywords: COMMUNICATIONS
    Type: Planetary and Space Science; 20; Mar. 197
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  • 96
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    Bureau and agency reports (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A summary of the work done by Geography and Human-Cultural Resources Work Group on EROS resources management program is given. Work covers archeological surveys, outdoor recreational planning, and engineering studies.
    Keywords: GEOPHYSICS
    Type: NASA. Manned Sapcecraft Center 4th Ann. Earth Resources Program Rev., Vol. 3; 12 p
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  • 97
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    Remote sensing of wet lands in irrigated areas (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The use of airborne remote sensing techniques to: (1) detect drainage problem areas, (2) delineate the problem in terms of areal extent, depth to the water table, and presence of excessive salinity, and (3) evaluate the effectiveness of existing subsurface drainage facilities, is discussed. Experimental results show that remote sensing, as demonstrated in this study and as presently constituted and priced, does not represent a practical alternative as a management tool to presently used visual and conventional photographic methods in the systematic and repetitive detection and delineation of wetlands.
    Keywords: GEOPHYSICS
    Type: NASA. Manned Spacecraft Center 4th Ann. Earth Resources Program Rev., Vol. 3; 10 p
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  • 98
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    Binary single-sideband phase-modulated communication systems. (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Single-sideband phase modulation (SSBPM), in which a signal is simultaneously phase- and amplitude-modulated by a signal and its Hilbert transform, is shown to be suboptimum for binary signaling in white Gaussian noise. An alternative single-sideband technique based on the properties of binary suppressed-carrier phase modulation is proposed and shown to give performance equivalent to the double-sideband version.
    Keywords: COMMUNICATIONS
    Type: IEEE Transactions on Information Theory; IT-18; Jan. 197
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  • 99
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    Computations of the aperture admittance of an axial slot on a dielectric coated cylinder. (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: An extensive set of curves for the aperture admittance of a waveguide-fed axial slot on a coated metal cylinder is presented for both an underdense plasma and a Teflon coating. Examination of these curves shows that a slot on a cylinder with a Ka of 2 to 3 has about the same aperture admittance as the identical slot opening onto a flat ground plane.
    Keywords: COMMUNICATIONS
    Type: IEEE Transactions on Antennas and Propagation; AP-20; Jan. 197
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  • 100
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    Rocket measurements of conjugate photoelectrons during the total solar eclipse of 7 March 1970 over Wallops Island. (1972)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Results of measurements made with a retarding potential analyzer on a Nike-Tomahawk rocket during the totality of the solar eclipse, showing definite evidence for the existence of photoelectrons from the conjugate hemisphere. Photoelectrons are observed in the altitude range from 120 to 260 km. The observed flux in the energy range from 2 to 30 eV is relatively constant above about 200 km, but decreased below that altitude. The flux of 5-eV energy electrons above 200 km altitude is about 10 to the 7th power electrons/cm/sec/eV. Higher-energy electrons were also observed, and it is possible that the energy content of these observed fluxes of conjugate-point photoelectrons is sufficient to maintain the observed electron densities and temperatures during the total eclipse.
    Keywords: GEOPHYSICS
    Type: Journal of Atmospheric and Terrestrial Physics; 34; Apr. 197
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