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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 307 records · Page 17

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NASA NTRS1972

Moonquakes and lunar tectonism results from the Apollo passive seismic experiment.

The natural seismicity of the moon appears to be very low relative to that of the earth. However, moonquakes do occur. They are detected by the stations of the Apollo seismic network at an average rate of 1800/yr at Station 14 and at lower rates at Stations 12 and 15. All of the moonquakes are small, and in the few cases for which the foci have been located, they occur at great depth (about 800 km). The frequency of occurrence of moonquakes is strongly correlated with lunar tides. The dynamic processes that generate quakes are clearly much less vigorous within the moon than they are within the earth.

Latham, G.↗

NASA NTRS1973

On the kinetic temperature of He/++/ in the solar wind.

Observations of solar-wind He(++) can be useful for studying dynamical processes in the interplanetary medium. Several processes which may influence the kinetic temperature are considered, and an attempt is made to inquire whether they can account for the observed fact that the kinetic temperature exceeds the proton temperature. Resonant heating is discussed qualitatively, and equations of resonant heating are developed. The proton and He(++) heating rates are determined for the least damped magnetoacoustic wave under various conditions.

Barnes, A.↗

NASA NTRS1973

Radio physics of the outer solar system.

The remote sensing of low frequency nonthermal radio emission is the astronomy of field and particle phenomena. Observations conducted from space lead to information about the composition and dynamic processes occurring in planetary magnetospheres as well as within the interplanetary and interstellar medium. The potential of this technique is demonstrated by considering observations obtained from earth orbit missions.

Stone, R. G.↗

NASA NTRS1973

Some recent developments in cometary physics.

Recent observations and associated theoretical developments bearing on the composition and structure of comets are briefly reviewed. The physical and dynamical processes in cometary atmospheres and ionospheres are discussed, and detailed hydrodynamic models of expanding multiconstituent cometary atmospheres corresponding both to a central nucleus as well as a central nucleus surrounded by a distributed source are presented for comparison with observation. It is argued that observed 'slow' speed for the neutral hydrogen is not incompatible with a purely H2O 'parent' source for that species.

Mendis, D. A.↗

NASA NTRS1973

Utilization of ERTS-1 data in North Carolina

The author has identified the following significant results. ERTS-1 imagery has been used to study forested wetlands, dynamic processes off Coastal North Carolina, and land use patterns in the Wilmington, North Carolina area. The thrust of the investigation is still involvement of state and regional agencies in the use of ERTS-1 imagery in solving some of their day-to-day problems.

Welby, C. W.↗

NASA NTRS1974

Friction and wear characteristics of carbon steels in vacuum

The nature of carbon steel friction and wear under vacuum conditions is described within the framework of general friction and wear theory. Friction is considered a dynamic process and wear is considered to be the result of a continuous sequence of transitions of the friction surface material from one state into another.

Verkin, B. I.↗

NASA NTRS1974

Studies in the use of cloud type statistics in mission simulation

A study to further improve NASA's global cloud statistics for mission simulation is reported. Regional homogeneity in cloud types was examined; most of the original region boundaries defined for cloud cover amount in previous studies were supported by the statistics on cloud types and the number of cloud layers. Conditionality in cloud statistics was also examined with special emphasis on temporal and spatial dependencies, and cloud type interdependence. Temporal conditionality was found up to 12 hours, and spatial conditionality up to 200 miles; the diurnal cycle in convective cloudiness was clearly evident. As expected, the joint occurrence of different cloud types reflected the dynamic processes which form the clouds. Other phases of the study improved the cloud type statistics for several region and proposed a mission simulation scheme combining the 4-dimensional atmospheric model, sponsored by MSFC, with the global cloud model.

Fowler, M. G.↗

NASA NTRS1974

Daytime three-dimensional drifts at Millstone Hill Observatory

Vertical drift measurements in the topside F region at midlatitudes have confirmed the importance of dynamical processes, but it has been difficult isolating those processes due to E X B drifts from those due to neutral winds. To remove this ambiguity, three-dimensional drift measurements were made at Millstone Hill Observatory with the steerable L-band radar in conjunction with the vertical UHF antenna. The geometry of the experiment is discussed and daytime drifts are presented. Unusual lifting of the F-layer peak was observed on two occasions. A reversal in the deduced meridional neutral wind is observed in one case and an enhanced eastward electric field in the other.

Carpenter, L. A.↗

NASA NTRS1974

Radiation damage and structure recorded at high resolution in grains from fine fractions of Luna 16 surface material

Samples returned to earth by Luna 16, were studied with a high voltage electron microscope for ultramicroscopic features. The following amazing features were noted in particles of surface material returned in all the lunar trips: A very high density of tracks of nuclear particles, ultrathin amorphous shells, highly rounded forms, and amazingly good ordering of crystal lattice. These features were used along with calibration experiments in solving the following problems: (1) determining the energy spectrum and chemical abundances of the very heavy nuclei in the solar wind and in the solar cosmic rays; (2) studying the past activity of the sun; (3) obtaining data on lunar dynamic processes affecting dust particles; (4) analyzing composite effects caused by penetration of solar wind into the lunar surface material; and (5) establishing the existence of the ancient lunar atmosphere and magnetic field.

Durrieu, L.↗

NASA NTRS1975

Oxygen systems engineering considerations

Special considerations for oxygen systems engineering with respect to system design, fabrication, and use are studied. The concerns for oxygen systems include the problems of leakage and erosion, difficulties that arise from dynamic processes, and the sensitivity of oxygen systems to contamination and cleaning requirements.

Source record↗

NASA NTRS1974

Magnetic storm dynamics of the thermosphere

A theoretical study of the Dst component of magnetic storms is presented. The dynamic characteristics are found significantly different for Joule dissipation and electron precipitation, leading to the conclusion that the former is probably the predominant heat source for the upper thermosphere. Composition measurements on OGO-6, which reveal markedly different characteristics in N2, O and He, can be explained on the basis of energy advection and diffusive mass transport by thermospheric winds. Essential features in the F2-region response are explicable in terms of these dynamic processes. Electric field induced motions are estimated and it is concluded that resultant adiabatic heating could be significant.

Mayr, H. G.↗

NASA NTRS1974

Waves and irregularities in the solar wind

This review is meant for the nonspecialist who wants a simple physical picture. Some simple calculations are given to show why waves and irregularities in the solar wind are of importance in obtaining a physical understanding of the dynamical processes occurring in the interplanetary medium. The basic physics of various phenomena observed in the heliosphere, resulting because of the presence of waves in the solar wind, is spelled out in some detail. The most fundamental point made in this review is that a considerable body of phenomena occurring in the solar wind are either caused directly or modified significantly by the turbulent waves that are always present in the solar wind.

Lee, M. A.↗

NASA NTRS1975

Theory and experiment of low transitions in CO discharge lasers

A self-consistent model which couples the kinetics of the electrons and heavy particles with the optical and fluid dynamic processes has been employed to identify the various parameters and explain the mechanism responsible for producing low-lying transitions in slow-flowing CO lasers. Both theory and experiment indicate that low-lying transitions can be achieved at low temperatures for low pressures (or low-flow rates) together with high partial pressures of He and N2. The role of N2 has been identified as an additive responsible for reducing the electron temperature to a range where the transfer of electrical power to the lower vibrational modes of CO is optimum.

Sidney, B.↗

NASA NTRS1974

Lunar surface dynamics - Some general conclusions and new results from Apollo 16 and 17

The exposure ages of Apollo 17 rocks as measured by tracks and rare gases are discussed and a description is given of an investigation of a unique rock. The investigation will be an aid for the establishment of the long-term energy spectrum of solar flare heavy particles. The track record of several Apollo 17 soils is examined. It is shown that the Apollo 17 deep drill stem might make it possible to extend the energy range over which the fossil record of galactic cosmic rays can be studied. A review is provided regarding the experimental data obtained for the rates of several dynamical processes on the lunar surface.

Crozaz, G.↗

NASA NTRS1975

New horizons

The contribution of space exploration and space related research to the future of man and the accomplishments of the space program are assessed. Topics discussed include: the role of applications satellites in crop surveillance, land use surveys, weather forecasting, education, communications, and pollution monitoring; planetary studies which examine the origin and evolution of the solar system, including dynamic processes that bear directly on earth's environment; and fuel conservation and development of new energy sources.

Source record↗

NASA NTRS1976

Theory of low transitions in CO discharge lasers

A self consistent theoretical model which couples the electron and heavy particle finite rate kinetics with the optical and fluid dynamic processes has been employed to identify the various parameters and explain the mechanism responsible for producing low lying transitions in slow flowing CO lasers. It is found that lasing on low lying transitions can be achieved at low temperatures for low pressures (or low flow rates) together with high partial pressures of the He and N2. The role of N2 has been identified as an additive responsible for reducing the electron temperature to a range where the transfer of electrical power to the lower vibrational modes of CO is optimum.

Sidney, B. D.↗

NASA NTRS1976

The topside ionosphere - A region of dynamic transition

The review article concentrates on dynamic processes at work in the topside ionosphere (between the F2 peak and about 3000 km) where the H ion dominates and ionic reactions can be neglected. The history of ionosphere and plasmasphere research using radio waves is reviewed. Low-speed and high-speed multispecies plasma ion flow is studied with various models (13-moment approximation, 5-moment approximation, kinetic models of the polar wind). Experimental observations of the plasmapause, results of vertical soundings of the topside, and global pole-to-pole distributions of ion composition, plasma temperature, and electron density are reviewed.

Banks, P. M.↗

NASA NTRS1976

Acceleration effects on the performance of solid-propellant rocket motors

Some acceleration effects on rocket performance have been well publicized. The dynamic process, characterized by marked increases in 'localized' burning rate, produces excessive case heating, slag retention, pressure buildup, and/or internal flow alterations. Data are presented illustrating drastic effects at low accelerations for sustainer type propellants and its relevance to several recent failures. Normalized orientation dependence of rate augmentation appears coupled to acceleration level and base burning rate. Effects appear influenced by propellant composition. Predictions using subscale motor data show good agreement with observed performance for ground spin and flight tests. Subscale test methods and results are also discussed.

Lucy, M. H.↗