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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 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

A system overview of the Aerospace Safety Research and Data Institute data management programs

The NASA Aerospace Safety Information System, is an interactive, generalized data base management system. The on-line retrieval aspects provide for operating from a variety of terminals (or in batch mode). NASIS retrieval enables the user to expand and display (review) the terms of index (cross reference) files, select desired index terms, combine sets of documents corresponding to selected terms and display the resulting records. It also allows the user to print (record) this information on a high speed printer if desired. NASIS also provides the ability to store the strategy of any given session the user has executed. It has a searching and publication ability through generalized linear search and report generating modules which may be performed interactively or in a batch mode. The user may specify formats for the terminal from which he is operating. The system features an interactive user's guide which explains the various commands available and how to use them as well as explanations for all system messages. This explain capability may be extended, without program changes, to include descriptions of the various files in use. Coupled with the ability of NASIS to run in an MTT (multi-terminal task) mode is its automatic accumulation of statistics on each user of the system as well as each file.

Source record↗
NASA NTRS1971

Discussion of paper by A. E. Ringwood, Petrogenesis of Apollo 11 basalts and implications for lunar origin.

Critical review of statements put forward by Ringwood about the origin of the moon. The composition of the lunar basalts is discussed, and it is shown that many theories for the origin of the moon can explain this composition satisfactorily. It is pointed out that the closeness of the relationship between Martian basalts and earth basalts is a matter of opinion, and that the major geochemical features that must be explained are certainly the low iron content in the moon and the depletion of volatiles. The manner in which various hypotheses of lunar origin deal with this explanation is examined.

Singer, S. F.↗
NASA NTRS1972

Corotation of an intermittent solar wind source

The measured electron content of the solar wind in mid-1970 exhibited a region of relatively high electron density that reappeared at intervals of about 27.8 days. It is shown that the repeating event cannot be reconciled with the concept of a long-enduring steady flow, even though the recurrence period is close to the rotation period of the sun. This evidence of transients is inferred from the short duration of each appearance of the interval of higher density; each should last for roughly one corotation interval if it is caused by a steady stream. The radio path was approximately 0.8 AU long, and the corotation interval exceeded 3 days. Other aspects of the content data patterns support the view that such transient events are common in the solar wind. The mid-1970 repeating event is an unusually good example of the intermittent character of flow regions in the solar wind that fluctuate on a time scale of days but endure as identifiable regions for many months. A sputtering corotating source of thin solar plasma streams could explain this series of events; it could also be explained in terms of a stream that is steady in density and speed but undulating north-south so that it passes into and out of the 0.8 AU radio path in a matter of a day or less.

Croft, T. A.↗
NASA NTRS1972

The light ion trough, the main trough, and the plasmapause

Extensive observations of mid-latitude depletions in electron and total ion density by both direct and indirect techniques, have prompted numerous studies of the possible association between these troughs, observed in the F-region, the topside ionosphere, and the plasmapause. One basic problem arises, in that while the plasmapause was detected as a global phenomenon both by VLF and ion composition measurements, the electron and ion density troughs were identified primarily as nightside features. This problem, as well as the difficulty in explaining various inconsistencies in relating the position of the plasmapause and the ionization trough, is explained by a close examination of the ion composition. In particular, ion composition results from the polar orbiting OGO satellites identify the persistence of a pronounced light ion trough in H(+) and He(+) identified by order of magnitude decreases in the light ion concentrations.

Taylor, H. A., Jr.↗
NASA NTRS1971

Remote Sensing of Sea Ice from Earth Satellites

The application of meteorological satellite data for mapping ice fields is discussed. The characteristics of the photographic records of sea ice formations are described. The derivation of the composite minimum brightness chart by computer processing of the mapped satellite vidicon data for several successive days is explained. The factors which create a quantitative delimiting of the sea ice conditions are explained.

Mcclain, E. P.↗
NASA NTRS1972

Users manual for Streamtube Curvature Analysis: Analytical method for predicting the pressure distribution about a nacelle at transonic speeds, volume 1

The computer program, Streamtube Curvature Analysis, is described for the engineering user and for the programmer. The user oriented documentation includes a description of the mathematical governing equations, their use in the solution, and the method of solution. The general logical flow of the program is outlined and detailed instructions for program usage and operation are explained. General procedures for program use and the program capabilities and limitations are described. From the standpoint of the grammar, the overlay structure of the program is described. The various storage tables are defined and their uses explained. The input and output are discussed in detail. The program listing includes numerous comments so that the logical flow within the program is easily followed. A test case showing input data and output format is included as well as an error printout description.

Keith, J. S.↗
NASA NTRS1973

Impulsive solar X-ray bursts: Bremsstrahlung radiation from a beam of electrons in the solar chromosphere and the total energy of solar flares

Analysis of various aspects of impulsive X-ray bursts (IXB's) has lead to the consideration of a model where the X-rays are produced by bremsstrahlung radiation from a beam of electrons directed toward the photosphere. It was found that in general the X-ray spectrum from such a beam will fall off more rapidly than when the effect of the beaming of radiation is neglected. Furthermore, the spectral index of the resulting X-rays appears to increase by about unity for X-ray energies 100 kev, a fact which may explain the observed cutoff in the spectrum of the IXB's. It is also shown that in such a model there is sufficient energy in the form of nonthermal electrons to explain the total energy (approximately 10 to the 32nd power ergs) of a flare.

Petrosian, V.↗
NASA NTRS1973

An experimental investigation of mesospheric ionization

Mesospheric ionization and its variability are examined. Data were obtained primarily by the parachute-borne blunt probe technique conducted in coordinated rocket experiments at White Sands Missile Range, New Mexico and Wallops Island, Virginia. Electrical conductivity measurements and deduced charge density values from ten rocket launches are presented and discussed. Positive ion conductivity and electron density were found to be relatively invariant with height between 45 and 60 km. Variations in positive conductivity of a factor of two and enhancements in negative conductivity by as much as a factor of four were measured by the blunt probe. A simple lumped parameter ion chemistry model is shown to satisfactorily explain the charge density values for the undisturbed lower D-region. Implications of the data in terms of this model are considered. The principal loss mechanism for positive ions in the 45 to 60 km. region is concluded to be dissociative recombination. Electron densities deduced from the conductivity data are explained by detachment involving a minor neutral constituent which is mixed between 65 and 45 km. and then cuts off sharply below 45 km. A correlation study involving blunt probe measurements shows relatively good agreement between variations in positive conductivity and temperature.

Mitchell, J. D.↗
NASA NTRS1972

Remarks on the heating of solar-wind protons.

The heating of solar-wind protons cannot be explained by the thermalization of those protons arising from the ionization of neutral hydrogen atoms traveling in the general direction of the sun. By requiring the heating to satisfy the experimental results of the T sub p versus V sub sw correlation, an efficiency function of thermalization of these incoming protons is obtained, and a value of the 'hot component' of the hydrogen population is about 0.05 per cu cm near 1 AU. This hot component hydrogen density is too high compared to recent estimates by satellite experiments of Lyman alpha radiation and other experiments, and therefore the suggested solar-wind heating mechanism is unimportant in explaining the T sub p versus V sub sw correlation.

Chao, J.-K.↗
NASA NTRS1972

The light-ion trough, the main trough, and the plasmapause.

Although the plasmapause has been detected as a global phenomenon by both VLF and ion composition measurements, the electron and ion density troughs have been identified primarily as nightside features. This problem, as well as the difficulty in explaining various inconsistencies in relating the position of the plasmapause and the ionization trough, is explained by a close examination of the ion composition, generally unavailable in previous trough studies. In particular, ion composition results from the polar-orbiting Ogo satellites identify the persistence of a pronounced light-ion trough (LIT) in H(+) and He(+), often identified by order-of-magnitude decreases in the light-ion concentrations, that occurs within a few degrees of latitude and reaches residual concentration levels of 100 to 1000 ions/cu cm near 60 deg dipole latitude. The LIT, observed both within the thermosphere and at high latitudes in the magnetosphere, has been correlated directly with the VLF whistler identification of the plasmapause.

Taylor, H. A., Jr.↗
NASA NTRS1972

Binaural signal detection - Equalization and cancellation theory.

The improvement in masked-signal detection afforded by two ears (i.e., binaural unmasking) is explained on the basis of a descriptive model of the processing of binaural stimuli by a system consisting of two bandpass filters, an equalization and cancellation mechanism, and a decision device. The main ideas of the model are initially explained, and a general equation is derived for the purpose of making quantitative predictions. Comparisons are then made between various special cases of this equation and experimental data. Failures of the preliminary model in predicting the data are considered, and possible revisions are discussed.

Durlach, N. I.↗
NASA NTRS1973

Josephson junction mixing.

A theory is presented which, though too simple to explain quantitative details in the Josephson junction mixing response, is sufficient for explaining qualitatively the results observed. Crucial to the theory presented, and that which differentiates it from earlier ones, is the inclusion of harmonic voltages across the ideal Josephson element.

Thompson, E. D.↗
NASA NTRS1973

Insulation commonality assessment (phase 1). Volume 2: Section 7.0 through 16.0

The heat transfer characteristics of various materials used for the thermal insulation of spacecraft are discussed. Techniques for conducting thermal performance analysis, structural performance analysis, and dynamic analysis are described. Processes for producing and finishing the materials are explained. The methods for determining reliability, system safety, materials tests, and design effectiveness are explained.

Source record↗
NASA NTRS1973

Behavior of hydrogen in alpha-iron at lower temperatures

Evidence is presented that the low temperature anomalies in the hydrogen occlusive behavior of alpha iron can be explained by means of a molecular occlusion theory. This theory proposes that the stable state of the absorbed hydrogen changes from atomic at high temperatures to molecular as the temperature is lowered below a critical value. Theories proposing to explain the anomalous behavior as being due to the capture, at lower temperatures, of hydrogen in traps are shown to be unacceptable.

Weizer, V. G.↗
NASA NTRS1973

The characteristics of a possible low altitude electron layer in the Martian atmosphere

The apparent diurnal Martian surface pressure variation, as deduced from radio occultation experiments, is discussed and explained as possibly arising from the effect of a low altitude electron layer. Possible source and loss mechanisms for the low altitude electron layer are presented and discussed. Time-dependent differential equations describing the electron layer are derived and then integrated to investigate the electron distribution resulting from the several processes that might occur in the atmosphere. It is concluded that the source mechanism is the sublimation of alkali atoms from a permanent dust layer (a dust layer of 0.2 micron particles of density 9/cu cm is sufficient), and that the dominant loss process must involve CO2 clustering to the alkali atoms. Using these processes, an electron layer is developed which would explain the apparent diurnal surface pressure.

Wallio, H. A.↗
NASA NTRS1974

Reflectance of vegetation, soil, and water

The author has identified the following significant results. Reflectance of crop residues, that are important in reducing wind and water erosion, was more often different from bare soil in band 4 than in bands 5, 6, or 7. The plant parameters leaf area index, plant population, plant cover, and plant height explained 95.9 percent of the variation in band 7 (reflective infrared) digital counts for cotton and 78.2 percent of the variation in digital counts for the combined crops sorghum and corn; hence, measurable plant parameters explain most of the signal variation recorded for corpland. Leaf area index and plant population are both highly correlated with crop yields; since plant population can be readily measured (or possibly inferred from seeding rates), it is useful measurement for calibrating ERTS-type MSS digital data in terms of yield.

Wiegand, C. L.↗
NASA NTRS1973

System design of the Pioneer Venus spacecraft. Volume 5: Probe vehicle studies

A summary of the key issues and studies conducted for the Pioneer Venus spacecraft and the resulting probe designs are presented. The key deceleration module issues are aerodynamic configuration and heat shield material selection. The design and development of the pressure vessel module are explained. Thermal control and science integration of the pressure vessel module are explained. The deceleration module heat shield, parachute and separation/despin are reported. The Thor/Delta and Atlas/Centaur baseline descriptions are provided.

Nolte, L. J.↗
NASA NTRS1974

The solar cycle variation of the solar wind helium abundance

A critical survey was made of the experimental evidence for a variation of the relative abundance by number h, (n alpha/np), of helium in the solar wind. The abundance is found to vary by delta h = 0.01 + or - 0.01 from 0.035 to 0.045 over solar cycle 20. Changes in the average bulk speed during the solar activity cycle was insufficient to account for this increase in h with the solar cycle. The slope of the linear relation between h and the plasma bulk speed is also found to vary, being greatest around solar maximum. An attempt is made to explain the 30% variation in h as the result of the variation in the number of major solar flares over a solar cycle. These obvious transients are apparently not numerous enough to explain the observed variation, but the reasonable expectation remains that the transients observed recently by Skylab which may occur more frequently than major flares could augment those associated with major flares. Since the solar wind flux is not observed to increase at solar maximum, the abundance of Helium cannot be proportional to the proton flux leaving the sun unless the solar wind comes from a smaller area of the sun at maximum than at minimum.

Ogilvie, K. W.↗