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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 91 records · Page 5
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NASA NTRS1970

On the use of space photography for identifying transportation routes: A summary of problems

It has been widely suggested that space photography may be used for updating maps of transportation networks. Proponents of the argument have suggested that color space photographs of the resolution obtained with Hasselblad 80 mm lenses (about 300 feet) contain enough useful information to update the extensions of major U. S. highways. The present study systematically documents for the Dallas-Fort Worth area the potential of such space photography in detecting, and to a lesser degree identifying, the existing road networks. Color separation plates and an enlargement of the color photograph were produced and all visible roads traced onto transparencies for study. Major roads and roads under construction were the most visible while lower class roads and roads in urban areas had the poorest return. Road width and classification were found to be the major determinant in visibility, varying from 100 per cent visible for divided highways to 15 per cent visible of bladed earth roads. In summary, space photographs of this resolution proved to be difficult to use for accurate road delineation. Only super highways in rural areas with the greatest road-width were completely identifiable, the width being about 1/3 that of the resolution cell.

Simonett, D. S.↗
NASA NTRS1972

SM91: Observations of interchange between acceleration and thermalization processes in auroral electrons

Results from a Nike-Tomahawk sounding rocket flight launched from Fort Churchill are presented. The rocket was launched into a breakup aurora at magnetic local midnight on 21 March 1968. The rocket was instrumented to measure electrons with an electrostatic analyzer electron spectrometer which made 29 measurements in the energy interval 0.5 KeV to 30 KeV. Complete energy spectra were obtained at a rate of 10/sec. Pitch angle information is presented via 3 computed average per rocket spin. The dumped electron average corresponds to averages over electrons moving nearly parallel to the B vector. The mirroring electron average corresponds to averages over electrons moving nearly perpendicular to the B vector. The average was also computed over the entire downward hemisphere (the precipitated electron average). The observations were obtained in an altitude range of 10 km at 230 km altitude.

Pongratz, M.↗
NASA NTRS1972

Remote sensing on Indian and public lands

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.

Torbert, G. B.↗
NASA NTRS1971

Rocket-based measurement of particle fluxes and currents in an auroral arc.

The rocket with the experiment was fired from Fort Churchill, Canada, over a homogeneous arc at 2000 local time on Feb. 26, 1969. Detectors measured the pitch-angle distribution of the fluxes of electrons with energies in the range from 2 to 18 and energies above 50 keV, and of protons with energies in the range from 2 to 18 and in the range from 80 to 1000 keV. The total backscattered flux was about 20% of the downward flux in the same energy range. No protons in the range from 2 to 18 keV, or any higher energy particles, were found in significant quantities. It was found that the energetic auroral electrons carry a substantial part of the Birkeland current. The arc extended at least 1500 km in an east-west direction and was not associated with substorm activity.

Vondrak, R. R.↗
NASA NTRS1972

Correlated satellite measurements of low-energy electron precipitation and ground-based observations of a visible auroral arc.

A comparison of low-energy charged-particle intensities measured with the low-altitude satellite Injun 5 and a ground-based observation of an auroral arc at Fort Churchill on December 21, 1968, during late local evening has established that an intense precipitation band of electron intensities provides the primary energy influx for the auroral light. This precipitation event was located poleward of and adjacent to the trapping boundary for more energetic electron (above 45 keV) intensities. Proton and electron intensities similar to those in the plasma sheet in the magnetotail were observed in a substantially less-intense zone positioned equatorward of and adjacent to the trapping boundary. The intense precipitation band of electron intensities poleward of the trapping boundary is interpreted as the signature of direct acceleration of magnetosheath electrons into the earth's atmosphere.

Ackerson, K. L.↗
NASA NTRS1972

Observed correlations between auroral and vlf emissions.

This paper presents a series of simultaneous observations of very-low-frequency radio noise by the Injun 5 satellite and of visual aurora along the same geomagnetic-field line by the Fort Churchill Auroral Observatory. Seven observations from the period of August 29, 1968, to March 4, 1969, are discussed. In 5 of the 7 events studied vlf hiss is observed in association with auroral-light emissions. These observations typically show the occurrence of vlf hiss in the general region of the auroral arc, with significant changes in the vlf spectrum sometimes observed in the immediate vicinity of the auroral arc. One event for which the associated charged-particle fluxes have been analyzed is investigated in detail. The vlf radio noise intensity for this event is among the largest observed with Injun 5 and is much greater than can presently be explained by an incoherent Cerenkov radiation mechanism.

Mosier, S. R.↗
NASA NTRS1972

Observations of fast auroral waves.

Results of simultaneous observation of a fast wave event from the Ester Dome Observatory (EDO) near College, Alaska, the Poker Flat Rocket Launching Facility (PKR), and Fort Yukon, Alaska (FYU). The display occurred on Mar. 27, 1971, and the general morphology is described and discussed. It is suggested that fast auroral waves occur when a preceding substorm has enhanced the particle population in the region of the magnetosphere near L = 6 in the midnight sector; then transverse hydromagnetic waves, associated with the onset of further local substorm activity, become visible through their action on this enhanced particle population as they propagate inwards in the equatorial region.

Boyd, J. S.↗
NASA NTRS1972

Extreme ultraviolet emissions from an aurora.

Two ultraviolet photometers were flown on a Javelin sounding rocket launched from Fort Churchill, Canada, on February 18, 1970, into a weak auroral breakup. The photometers covered the wavelength bands 300-1000 A and 1050-1500 A and observed the aurora while the rocket was above the emitting regions. The observed radiations were found to originate from the visible and X-ray auroral forms recorded by ground-based all-sky cameras and onboard gas proportional X-ray counters. The intensities in the 1050- to 1500-A band were compatible with previous experimental data and available theoretical intensity calculations.

Paresce, F.↗
NASA NTRS1973

Effective use of ERTS multisensor data in the Great Plains

The author has identified the following significant results. In the case of rangelands, manipulation of the digitized material from photographic recordings revealed that the mode-seeking program using only one vegetation group gave the best output map. Efficient mapping of this imagery will possibly require the use of narrow band filters. In the case of cropland, the results obtained with the K-class classifier are shown. Using one feature, the highest percent correct classification was obtained using band 6. Using two features, best results were obtained using bands 4 and 6 and 5 and 6. Specific results obtained with various bands are discussed. In the case of land systems, the eroded shale soils located along the Missouri River reservoirs in South Dakota above the Fort Randall and Big Bend Dams are clearly visible on the IR bands of ERTS scene 17 August, 1972, image description number 1025-16551. The appearance of various types of soil formations is described.

Myers, V. I.↗
NASA NTRS1973

Pollution monitoring in Lake Champlain using ERTS-1 imagery

The author has identified the following significant results. Band 4 imagery of April 7 and 25 show contrasting pollution effects due to seasonal and discharge variations. The pollution plume emanating from the International Paper Co. mill just north of Fort Ticonderoga was first detected on October 10 ERTS-1 imagery and now has been documented during spring high lake level conditions. The plume was observed extending further to the north and east than under low water conditions of October 10. This northward extension reflects a stronger northward current flow expected in the turbid southern leg of Lake Champlain. The extensive plume of April 25 represents full plant operation while the April 5 scene shows some plume traces directly over the submerged diffuser, discharge pipe representing minimal discharge during weekend plant operation. The ERTS-1 documentation will be used in developing a model of plume behavior under varying environmental conditions and will hopefully serve to assist in a major resource decision pending at U.S. Supreme Court level.

Lind, A. O.↗
NASA NTRS1972

Cosmic dust in the mesosphere.

Study of the nature of cosmic dust particles collected by two recoverable rockets launched at Fort Churchill, Canada, in the spring of 1970, before the noctilucent cloud season in order to avoid the interference of uplifted atmospheric aerosols during the determination of the concentration of background cosmic dust. The study was designed to verify the results of a previous study for which dust particles were collected in the summer of 1968 by a rocket launched through a noctilucent cloud at the same location. The findings support the hypothesis that occasional high concentrations of dust in the mesosphere are due to uplifted aerosols which could be of a terrestrial or cosmic origin.

Farlow, N. H.↗
NASA NTRS1973

Cosmic ray electrons of E greater than 1 Gev - Some new measurements and interpretations.

In the summer of 1971 new measurements were made of the primary electron spectrum from 1 to 20 GeV with an electron spectrometer telescope at Fort Churchill. This telescope has been calibrated by using electrons and pions of 0.5 to 15 GeV at the Stanford Linear Accelerator in early 1971 and again in 1972. The calibration results suggest that the events observed are due to interactions of high-energy protons. The measured primary electron spectrum is uncomfortably close to that calculated for secondary electrons produced by the interaction of cosmic ray nuclei with interstellar hydrogen in the Galaxy, and therefore the question of the origin of the high-energy electrons is reopened. The problem of the age of cosmic ray electrons must also be reexamined if the measured spectrum is found to extend to still higher energies.

Webber, W. R.↗
NASA NTRS1973

Relations between ionospheric electric fields and energetic trapped and precipitating electrons.

Balloon-borne electric field and X ray detectors have been flown from Fort Churchill and from near the foot of the magnetic field line on which the ATS 5 satellite is located in order to obtain satellite and balloon measurements of trapped and precipitating particles and to compare them with balloon measurements of the ionospheric electric field. The approximately 80 hours of coordinated data show that nighttime precipitation events (1) are preceded by enhancements of the westward component of ionospheric electric field about 70% of the time, (2) cause the westward electric field strength to decrease about 70% of the time, (3) are unrelated to variations of the southward component of the ionospheric electric field. The westward electric field enhancement before many precipitation events occurs when the trapped electron flux is at or near the stable trapping limit.

Mozer, F. S.↗
NASA NTRS1973

Twin payload observations of incident and backscattered auroral electrons.

Energy spectra and pitch angle distributions of auroral electrons have been measured in a premidnight multiple arc auroral display by a Javelin rocket containing two identical payloads that separated in flight. The rocket was launched from Fort Churchill, Canada, at 0459 UT on March 2, 1968, and covered an altitude range up to 800 km. The electron energy spectra between 40 eV and 20 keV show a 'continuum' spectrum with a superimposed energetic peak. The center energy of the peak was observed to shift from 10-12 keV over the arcs to 2-3 keV between the arcs. This spectral structure is shown to be similar to the inverted 'V' structure reported by other investigators. The in flight separation of the two payloads allowed investigation of spatial versus temporal effects in the auroral precipitation.

Reasoner, D. L.↗
NASA NTRS1974

The cosmic ray electron spectrum and its modulation from 1968 through 1972

Over the past five years we have measured the energy spectrum of primary cosmic ray electrons with both a balloon-borne and a satellite absorption spectrometer. All of the balloon flights used identical equipment that was launched each summer from Fort Churchill, Manitoba, Canada. The satellite, OGO-5, has been in an eccentric orbit since March 1968. Together these instruments provide the electron spectrum over a range of energy from 20 MeV to 20 GeV. This wide range and the substantial span of time covered by the measurements permit a detailed study of the solar modulation of electrons. These results are compared with the modulation of the nuclear components as observed by a neutron monitor and interpreted using the cosmic ray transport equation.

Fulks, G.↗
NASA NTRS1974

An investigation of wave-particle interactions and particle dynamics using electron beams injected from sounding rockets

Electrons with energy up to 40 kV have been injected into semi-trapped orbits from sounding rockets at Wallops Island, Virginia, and at Fort Churchill, Manitoba, Canada. By directing the rocket trajectory to have a horizontal component which in direction and speed matched the bounce displacement of the injected electrons, it was possible to detect conjugate echoes at Wallops and possibly at Churchill, and to study the distribution of the echoes in space, time and energy. By combining observations of many echoes, a composite picture can be obtained of the beam patterns. Atmospheric scattering at the conjugate point of Wallops Island has been extensively studied, and the process produces a scale width of 5-10 m, but with an echo intensity which is only 10% of theoretical estimates.

Winckler, J. R.↗
NASA NTRS1973

Ionospheric effects on one-way timing signals

A proposed navigation concept requires that a user measure the time-delay that satellite-emitted signals experience in traversing the distance between satellite and user. Simultaneous measurement of the propagation time from four different satellites permits the user to determine his position and clock bias if satellite ephemerides and signal propagation velocity are known. A pulse propagating through the ionosphere is slowed down somewhat, giving an apparent range that is larger than the equivalent free space range. The difference between the apparent range and the true range, or the free space velocity and the true velocity, is the quantity of interest. This quantity is directly proportional to the total electron content along the path of the propagating signal. Thus, if the total electron content is known, or is measured, a perfect correction to ranging could be performed. Faraday polarization measurements are continuously being taken at Fort Monmouth, N. J., using beacon emissions of the ATS-3 (137.35 MHz) satellite. Day-to-day variability of the diurnal variation of total electron content values is present with differences of up to 50% or more not being uncommon. In addition, superposed on the overall diurnal variation are smaller scale variations of approximately 5 to 10% of the total content which are attributed to ionospheric density irregularities.

Soicher, H.↗
NASA NTRS1974

Ground effects on Loran-C signals

In conjunction with the test and evaluation of the position fixing capabilities of the Army Manpack Loran Receiver AN/PSN-6, an extensive series of time difference and signal amplitude measurements were made within a 100 km map grid square encompassing Fort Monmouth, New Jersey. The test location is within the coverage area of the East Coast Loran-C Chain. The data were used to develop a simple smooth-earth model for the test area as well as to estimate the magnitude and distributions of deviations from this model. Local propagation processes associated with topographic features and the grid of overhead wires in the test area are shown to contribute to the deviations from the model.

Pearce, D. C.↗