Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Subsurface”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Research needs in ocean color data analysis

The success of the effort to extract several subsurface oceanographic parameters from remotely sensed ocean color data will depend to a great extent upon the existence of adequate theoretical models relating the desired oceanographic parameters to the upwelling radiances to be observed. In order to guide the development of these models, and to check their accuracies, a considerable amount of experimental work must be performed. The theoretical and experimental work needed to develop techniques for the quantitative analysis of satellite ocean color data is described.

Mccluney, W. R.↗
NASA NTRS1973

Volatile-rich lunar soil - Evidence of possible cometary impact.

A subsurface Apollo 16 soil, 61221, is much richer in volatile compounds than soils from any other locations or sites as shown by thermal analysis-gas release measurements. A weight loss of 0.03% during the interval 175 to 350 C was associated with the release of water, carbon dioxide, methane, hydrogen cyanide, hydrogen, and minor amounts of hydrocarbons and other species. These volatile components may have been brought to this site by a comet, which may have formed North Ray crater.

Gibson, E. K., Jr.↗
NASA NTRS1973

Thermal properties of the Galilean satellites.

Radiometry in the 20-micron band of eclipses of each of the four Galilean satellites of Jupiter provides information about the thermal properties of the uppermost surface layers of these bodies. Their thermal inertias are all smaller than those of the moon or of Mercury; there is no evidence for atmospheres, and where the data are of high quality vertically homogeneous thermal properties are excluded. The thermal properties, together with other observational evidence, suggest that the surfaces of these satellites are largely composed of ices. A thin coating of frost provides the upper, low-conductivity layer, while the subsurface material maintains a high thermal conductivity by fusion of a mixture of ice and rock.

Morrison, D.↗
NASA NTRS1973

Ten-micron eclipse observations of Io, Europa, and Ganymede.

Eclipse observations of Jupiter's satellites Io, Europa, and Ganymede have been obtained in an 8 to 14-micron band pass during 1971. The simplest thermal model able to explain the data for each satellite is a two-layer surface structure with an upper layer, only a few millimeters thick, having low thermal conductivity consistent with fine rock powder or frost, and a subsurface having high thermal conductivity consistent with solid rock or dense ice. The upper layer on Io appears to be different from that on Europa and Ganymede, but the two-layer model fits all three satellites.

Hansen, O. L.↗
NASA NTRS1973

Fossil track and thermoluminescence studies of Luna 20 material.

Track densities in 85 feldspar crystals from L-2009 range from 2,500,000 per sq cm to greater than one billion per sq cm. This track distribution represents an intermediate case between what have been previously defined as lightly and heavily irradiated soils and suggests that the Luna 20 sample consists of a mixture of a mature, heavily irradiated component with another, lightly irradiated component. Using a two-component mixing model, the age of the lightly irradiated component is about 270,000,000 yr. It is possible, but by no means certain, that this is associated with the formation of the crater Apollonius C. At about 200 C the ratio of natural thermoluminescence to that induced by a standard irradiation is similar to that in Apollo 12 and 14 cores below about 7 cm. This confirms that most of the Luna 20 sample represents subsurface material.

Crozaz, G.↗
NASA NTRS1973

Interference patterns of a horizontal electric dipole over layered dielectric media.

Interference patterns for electromagnetic fields due to a subsurface reflector below a layered lossy dielectric are calculated with the geometrical optics approximation for use in interpreting data to be collected on the moon by Apollo 17 as well as data currently being obtained on terrestrial glaciers. The radiating antenna lies on the surface. All six field components are calculated and studied. For the endfire solutions, the peak of the first reflected wave is found to be different from that of the broadside ones. To facilitate a physical discussion, we plotted the radiation patterns due to the antenna on the surface.

Tsang, L.↗
NASA NTRS1973

Recent observations of Jupiter's North North Temperate Belt Current B.

An outbreak of thirteen spots in Jupiter's North North Temperate Belt Current B was observed in 1972. These have been measured and compared with measures of the two most previous outbreaks. The drift in longitude of a hypothetical source supports both Reese's original hypothesis of a subsurface source, and Solberg's observation that its period is close to that of System III. There is some evidence that long-enduring atmospheric features exist at lower, unobservable depths.

Minton, R. B.↗
NASA NTRS1973

The greenhouse of Titan.

Analysis of non-gray radiative equilibrium and gray convective equilibrium on Titan suggests that a massive molecular-hydrogen greenhouse effect may be responsible for the disagreement between the observed IR temperatures and the equilibrium temperature of an atmosphereless Titan. Calculations of convection indicate a probable minimum optical depth of 14 which corresponds to a molecular hydrogen shell of substantial thickness with total pressures of about 0.1 bar. It is suggested that there is an equilibrium between outgassing and blow-off on the one hand and accretion from the protons trapped in a hypothetical Saturnian magnetic field on the other, in the present atmosphere of Titan. It is believed that an outgassing equivalent to the volatilization of a few kilometers of subsurface ice is required to maintain the present blow-off rate without compensation for all geological time. The presence of an extensive hydrogen corona around Titan is postulated, with surface temperatures up to 200 K.

Sagan, C.↗
NASA NTRS1974

Glass fiber addition strengthens low-density ablative compositions

Approximately 15% of E-glass fibers was added to compositions under test and greatly improved char stability. Use of these fibers also reduced thermal strains which, in turn, minimized char shrinkage and associated cracks, subsurface voids, and disbonds. Increased strength allows honeycomb core reinforcement to be replaced by equivalent amount of glass fibers.

Chandler, H. H.↗
NASA NTRS1973

Lunar thermal measurements in conjunction with Project Apollo

Problems related to the feasibility of measuring lunar heat flow at the lunar surface are analyzed, and the findings which required that a drill be developed for lunar use are discussed. Numerical simulations were made of the in situ measurement of lunar thermal conductivity using a circular ring source of heat. The results of these simulations formed the basis for the criteria used in designing a subsurface thermal probe for ALSEP. Preliminary analyses are presented on the data obtained from the Apollo 15 and 17 missions.

Clark, S. P., Jr.↗
NASA NTRS1974

Ocean color spectrum calculations

The development is considered of procedures for measuring a number of subsurface oceanographic parameters using remotely sensed ocean color data. It is proposed that the first step in this effort should be the development of adequate theoretical models relating the desired oceanographic parameters to the upwelling radiances to be observed. A portion of a contributory theoretical model is shown to be described by a modified single scattering approach based upon a simple treatment of multiple scattering. The resulting quasi-single scattering model can be used to predict the upwelling distribution of spectral radiance emerging from the sea. The shape of the radiance spectrum predicted by this model for clear ocean water shows encouraging agreement with measurments made at the edge of the Sargasso Sea off Cape Hatteras.

Mccluney, W. R.↗
NASA NTRS1973

Soil mechanics

The soil mechanics experiment on the Apollo 17 mission to the Taurus-Littrow area of the moon is discussed. The objectives of the experiment were to determine the physical characteristics and mechanical properties of the lunar soil at the surface and subsurface in lateral directions. Data obtained on the lunar surface in conjunction with observations of returned samples of lunar soil are used to determine in-place density and porosity profiles and to determine strength characteristics on local and regional scales.

Mitchell, J. K.↗
NASA NTRS1973

Surface electrical properties experiment

The surface electrical properties (SEP) experiment was used to explore the subsurface material of the Apollo 17 landing site by means of electromagnetic radiation. The experiment was designed to detect electrical layering, discrete scattering bodies, and the possible presence of water. From the analysis of the data, it was expected that values of the electrical properties (dielectric constant and loss tangent) of lunar material in situ would be obtained. The basic principle of the SEP experiment is interferometry. This principle involves only the interference of two or more waves to produce an interference pattern. The inversion of the interference pattern in terms of the spatial distribution of the electrical properties is the basic aim of the experiment (fig. 15-1). The experiment is most easily understood in terms of a single dipole antenna for radiating electromagnetic energy and a loop receiver for measuring the magnitudes of the fields.

Simmons, G.↗
NASA NTRS1973

Apollo lunar sounder experiment

The four basic data products from the ALSE are sounding, profiling, imaging, and noise measurements. Attention was concentrated on the first three products, and both theory and preliminary results are presented. Background information is presented on the experiment and on the data products. Preliminary examples of the types of analyses that can be performed and the conclusions to which they can lead are included. Preliminary analysis of the data for subsurface features was successful in indicating with a high probability the capability of the ALSE to achieve its fundamental goal of substrate sounding. The imagery and profiling data are useful immediately for geologic interpretation, as demonstrated.

Phillips, R. J.↗
NASA NTRS1974

Use of visible, near-infrared, and thermal infrared remote sensing to study soil moisture

Two methods are described which are used to estimate soil moisture remotely using the 0.4- to 14.0 micron wavelength region: (1) measurement of spectral reflectance, and (2) measurement of soil temperature. The reflectance method is based on observations which show that directional reflectance decreases as soil moisture increases for a given material. The soil temperature method is based on observations which show that differences between daytime and nighttime soil temperatures decrease as moisture content increases for a given material. In some circumstances, separate reflectance or temperature measurements yield ambiguous data, in which case these two methods may be combined to obtain a valid soil moisture determination. In this combined approach, reflectance is used to estimate low moisture levels; and thermal inertia (or thermal diffusivity) is used to estimate higher levels. The reflectance method appears promising for surface estimates of soil moisture, whereas the temperature method appears promising for estimates of near-subsurface (0 to 10 cm).

Blanchard, M. B.↗
NASA NTRS1973

Communications of the Lunar and Planetary Laboratory: Communications nos. 173-183, volume 9, part 5

Short discussions are presented on: (1) multicolor photography of Jupiter; (2) narrow band photography of Jupiter and Saturn; (3) photographic observations of the occulation of Beta Scorpii by Jupiter; (4) development of the June 1971 South Equatorial Belt Disturbance on Jupiter; (5) rotation period for subsurface source in the NNTeB of Jupiter; (6) correlation between color of Jovian clouds and their 5 micron temperatures; (7) and observations of Jupiter's North North Temperature Belt Current B.

Kuiper, G. P.↗
NASA NTRS1973

Recent observations of Jupiter's north north temperature belt current B

An outbreak of thirteen spots in Jupiter's North North Temperature Belt Current B was observed in 1972. These have been measured and compared with measures of the two most previous outbreaks. The drift in longitude of a hypothetical source supports both Reese's original hypothesis of a subsurface source, and Solberg's observation that its period is close to that of System 3. There is some evidence that long-enduring atmospheric features exist at lower, unobservable depths.

Minton, R. B.↗
NASA NTRS1974

An evaluation of the suitability of ERTS data for the purposes of petroleum exploration

This experiment was designed to determine the types and amounts of information valuable to petroleum exploration extractable from ERTS data and the cost of obtaining the information using traditional or conventional means. It was desired that an evaluation of this new petroleum exploration tool be made in a geologically well known area in order to assess its usefulness in an unknown area. The Anadarko Basin lies in western Oklahoma and the panhandle of Texas. It was chosen as a test site because there is a great deal of published information available on the surface and subsurface geology of the area, and there are many known structures that act as traps for hydrocarbons. This basin is similar to several other large epicontinental sedimentary basins. It was found that ERTS imagery is an excellent tool for reconnaissance exploration of large sedimentary basins or new exploration provinces. For the first time, small and medium size oil companies can rapidly and effectively analyze exploration provinces as a whole.

Collins, R. J.↗