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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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Two fluid continuum theory of Thomson scattering extended to uniform DC magnetic field and electron drift, finding backscattered power dependent on magnetism
Output pulse amplitude from lithium-drifted detector-amplifier combination under conditions of carrier diffusion and bulk and surface recombination
Unstable collisional drift waves in high density ionized Li arc plasma, possibly causing anomalous losses and fluctuations
Mars surface harmonics and continental drift from radar and spectroscopic topographic height determination
Magnetic drift wave instabilities in plasmas with nonuniform density and temperature gradient
Neutron irradiated and unirradiated Ta sheathed BeO insulated grounded junction thermocouples drift measurement
Thermal emf changes for noble and refractory metal thermocouples, determining drift in high temperature air, Ar and vacuum environments for long time periods
Inhomogeneous high-beta collisionless plasma temperature gradient effects on ion-acoustic and Alfvenic drift instabilities
Magnetic drift waves near proton cyclotron frequency, noting magnetic field gradient role in plasma instability
Investigations were undertaken to determine the properties of shallow aquifers and related features that influence electromagnetic energy, to determine how these properties can be detected remotely, and to establish remote sensing procedures for aiding in ground water mapping. The direct influence of aquifier characteristics on surface thermal contrasts is discussed. Conclusions reached for late summer, predawn missions were: (1) Dynamic thermal changes near the surface can be used for thermal infrared sensing to detect shallow aquifers in glacial drift. (2) Under ideal conditions, surface temperatures may be used to predict certain features related to the occurrence of shallow aquifers. (3) The timing of missions and the optimum meteorological conditions occurring prior to and during the mission are critical for night thermal missions. (4) Repetitive flights made under variable conditions provide additional evidence to verify the occurrence of shallow aquifers. (5) Imagery from this investigation, along with ERTS-simulated imagery, indicates the feasibility of applying ERTS A and B data to reconnaissance studies for detection of shallow aquifers.
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.
Apollo 9 photographs of the region northwest of the Gulf of Tadjura were studied. The occurrence of a large region of basement rocks, probably crystalline in nature, with a strongly faulted overlayer was recognized and has been named the Tadjura uplift. Study of this region is adding detailed knowledge to the literature on the phenomenon of plate drift in the southern Red Sea region.
In the summer of 1969, a deep submersible drifted for 30 days below the surface of the Gulf Stream, while operated by a six man crew. The main purpose of the mission was oceanographic research. The crew's activities and completely self-contained environment resembled those of a space station such as Skylab. Because of these similarities aspects of onboard vehicle maintenance during the actual conduct of a scientific mission were investigated. The maintainability study was accomplished in six distinct phases. Two useful plots of manpower distribution were developed. A maintenance action summary is presented in a table.
It is argued that the cyclotron drift instability (coupled ion waves and electron Bernstein modes) can explain many structural features of the weak electrostatic turbulence observed in bow shock magnetic-field gradients and thus that it provides a more attractive speculation than the ion acoustic or Buneman instabilities previously suggested as weak turbulence sources.
A technique has been developed to measure the electromagnetic east-west drift velocity of the F region ionosphere by means of the Jicamarca incoherent scatter radar. Results show a fairly consistent behavior from day to day even during a magnetically disturbed day. Velocities are westward with a maximum of the order of 50 m/sec during the day, and eastward with a maximum of the order of 135 m/sec during the night. They are shown as experimental evidence for the superrotation of the neutral atmosphere at equatorial latitudes, but with a velocity smaller than the values inferred from satellite drag.
Velocity distribution functions of both the electron and the proton component of the magnetospheric plasma are measured in 62 logarithmically spaced steps from 50 eV to 50 keV by an instrument carried upon the ATS-5 spacecraft in circular synchronous orbit (6.6 earth radii). Oscillations which appear to be collisionless drift waves having periods of several minutes or longer are found in this data. Linearized wave theory can be used to predict the theoretical perturbation distribution function in terms of the perturbing fields and the equilibrium distribution function. The functional dependence of the theoretical perturbation distribution function upon particle energy can then be compared with that of the measured perturbation.
The facsimile camera is an optical-mechanical scanning device which has become an attractive candidate as an imaging system for planetary landers and rovers. This paper presents electronic techniques which permit the acquisition and reconstruction of high quality images with this device, even under varying lighting conditions. These techniques include a control for low frequency noise and drift, an automatic gain control, a pulse-duration light modulation scheme, and a relative spectral gain control. Taken together, these techniques allow the reconstruction of radiometrically accurate and properly balanced color images from facsimile camera video data. These techniques have been incorporated into a facsimile camera and reproduction system, and experimental results are presented for each technique and for the complete system.
Instrumented model drogue tests were conducted in a ship model towing tank. The purpose of the tests was to observe and measure deployment and drag characteristics of such shapes as parachutes, crossed vanes, and window shades which may be employed in conjunction with free drifting buoys. Both Froude and Reynolds scaling laws were applied while scaling to full scale relative velocities of from 0 to 0.2 knots. A weighted window shade drogue is recommended because of its performance, high drag coefficient, simplicity, and low cost. Detailed theoretical performance curves are presented for parachutes, crossed vanes, and window shade drogues. Theoretical estimates of depth locking accuracy and buoy-induced dynamic loads pertinent to window shade drogues are presented as a design aid. An example of a window shade drogue design is presented.