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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Solution of the equation of heat conduction with time dependent sources: Programmed application to planetary thermal history

A computer program (Program SPHERE) solving the inhomogeneous equation of heat conduction with radiation boundary condition on a thermally homogeneous sphere is described. The source terms are taken to be exponential functions of the time. Thermal properties are independent of temperature. The solutions are appropriate to studying certain classes of planetary thermal history. Special application to the moon is discussed.

Conel, J. E.↗
NASA NTRS1975

History of Manned Space Flight

U.S. manned space projects from Mercury Redstone 3 through Skylab 4 are briefly described including dates, flight duration, crew, and number of earth/moon orbits. The flight costs of each project are itemized. Highlights in the history of the manned space program from 1957 to February, 1974 are included.

Source record↗
NASA NTRS1974

Martian planetwide crater distributions - Implications for geologic history and surface processes

Three different diameter size ranges are considered in connection with the Martian crater distribution, taking into account small craters from 0.6 to 1.2 km, intermediate-sized craters from 4 to 10 km, and large craters with diameters exceeding 20 km. One of the objectives of the investigation reported is to establish the effects of eolian processes in the modification of craters in the different size ranges. Another objective is concerned with a description of the genetic relationships among the three size ranges of craters. Observables related to the relative age of geologic provinces are to be separated from observables related to geographic variations in eolian transport and deposition. Lunar and Martian cratering histories are compared as a basis for establishing relative and absolute time scales for the geological evolution of Mars.

Soderblom, L. A.↗
NASA NTRS1975

Tidal friction and the early history of the moon's orbit

The present work investigates the consequences implied by various rheological models of the early earth for the orbital history of the moon subsequent to its formation. Models of the earth that yield small tidal angles, such as low-viscosity models, imply that the moon never orbited in the earth's equatorial plane, thereby ruling out an equatorial origin for the moon. A high-viscosity model is shown to permit the moon to originate in the equatorial plane and still account for the present-day characteristics of the moon's orbit.

Rubincam, D. P.↗
NASA NTRS1974

Mercury bombardment ion thrusters - Development status, performance levels, and test history

The present work describes the development status, performance levels, and life test history of 5-cm, 8-cm, and 30-cm mercury bombardment ion thrusters and their respective power processors. A 2.6 kW, 30-cm thruster module and its power processor unit are now available that established the performance required by interplanetary and geosynchronous orbit raising missions. An 8-cm thruster with nominal 4.5 mN thrust level capability has demonstrated a high performance over a wide range of thrust and operational life.

Molitor, J. H.↗
NASA NTRS1974

Formational history of lunar rocks - Applications of experimental geochemistry of the opaque minerals

Experimental data on the cooling histories of lunar rocks are presented along with a descriptive mineralogy of certain opaque minerals in Apollo 17 samples. Lunar rocks having Zr partitionings of coexisting ilmenite and ulvospinel indicative of high-temperature equilibrium (above 1000 C) appear to have cooled rapidly to temperatures below 800-900 C. The Ti content of troilite coexisting with ilmenite can be used to differentiate rock fragments which are mineralogically and texturally similar. It is found that Cr and Mg partitionings between coexisting armalcolite and ilmenite vary notably between rocks so that they can be used to distinguish otherwise similar samples. The spinels are analyzed as varieties of chromian ulvospinel and titanian chromite.

Taylor, L. A.↗
NASA NTRS1974

Thermal histories and crystal distributions in partly devitrified lunar glasses cooled by radiation

Calculations of the expected crystallization behavior of selected lunar compositions (60095 and 14259) are presented. Knowledge of this behavior combined with measurements of the state of crystallinity in partially devitrified lunar samples permits the determination of the thermal history of the samples. The state of crystallinity of a specimen is described by a statistical crystal distribution function psi. The heat flow problems of a plate of opaque glass quenched on an aluminum block and of a semi-transparent glass sphere cooling by radiation are analyzed. The results are combined with laboratory measurements of the crystal growth velocity and the viscosity, and with theoretical expressions for the nucleation frequency (homogeneous and heterogeneous) to obtain psi. It is found that the calculated psi is much too large in comparison with laboratory experiments on lunar samples. Possible reasons for the discrepancy are discussed, and the most likely cause is that the assumed nucleation barrier is too small. It also appears likely that these materials have relatively few nucleating heterogeneities.

Hopper, R. W.↗
NASA NTRS1975

Design aspects of zeppelin operations from case histories

Some widely held beliefs concerning the practicability of rigid airships in air carrier operations are discussed. It is shown by a review of past operational experience, and some basic aerostatic theory, their actual record and the reasons for their demise. Problems of atmospheric density and temperature variations, meteorological factors, aerodynamic stability and control, and mooring difficulties are discussed and related to actual case histories. Structural and flight efficiencies are compared to airplane efficiencies for airplanes contemporary with the zeppelin as well as modern designs. The difficulty of supporting new, commercial airship developments on an economic basis is made clear.

Maiersperger, W. P.↗
NASA NTRS1975

A study of the financial history of the U.S. scheduled airlines and the improvement of airline profitability through technology

The financial history of the U.S. scheduled airline industry was investigated to determine the causes of the erratic profit performance of the industry and to evaluate potential economic gains from technology advances of recent years. Operational and economic factors affecting past and future profitability of the industry are discussed, although no attempt was made to examine the profitability of individual carriers. The results of the study indicate that the profit erosion of the late 1960's and early 1970's was due more to excess capacity than to inadequate fare levels, but airline problems were severely compounded by the rapid fuel price escalation in 1974 and 1975. Near-term solutions to the airline financial problems depend upon the course of action by the industry and the CAB and the general economic health of the nation. For the longer term, the only acceptable alternative to continued fare increases is a reduction in unit operating costs through technological advance. The next generation of transports is expected to incorporate technologies developed under Government sponsorship in the 1960's and 1970's with significant improvements in fuel consumption and operating costs.

Wilcox, D. E.↗
NASA NTRS1976

History of the dust released by comets

The Finson-Brobstein theory is used to examine production and history of dust released from periodic comets and to compare dust size distribution in relation to the Zodiacal cloud. Results eliminate all of the bright new comets from contributors to the Zodiacal cloud. Among the periodic comets, all particles of size much smaller than 10 micrometer are also lost. Only the large particles remain as possible contributors.

Jambor, B. J.↗
NASA NTRS1976

Orders of magnitude: A history of NACA and NASA, 1915-1976

A brief history of aeronautics and space exploration is presented. The Federal government's role in contributing, by research and development, to the advancement of aeronautics and space exploration is emphasized. The flight of man is traced from Kitty Hawk to walks and rides on the surface of the moon. Orbiting Solar Observatories, Orbiting Observatories, planetary exploration (Mariner Space Probes, Pioneer Space Probes) the Earth Resources Program, and Skylab are included. The development of the space shuttle is also discussed.

Anderson, F. W.↗
NASA NTRS1975

History of Boulder 1 at Station 2, Apollo 17 based on trace element interrelationships

Correlations among the trace and minor element pairs Cl and Br, Cl and P2O5, and Ru and Os, present in parent igneous rocks, generally survived the processes of boulder breccia formation. Fractions of Cl, Br, and Hg that are mobilized by water leaching or volatilization at moderate temperatures place constraints on the thermal history of Boulder 1 and its component breccias. Since, and possibly during, consolidation, the boulder has probably not been subjected to temperatures in excess of 450 C. The parent rocks of the Apollo 17 boulder and breccia samples studied could have been derived from two initial magmas. Vapor clouds from apparently external sources permeated the source regions of the boulders.

Jovanovic, S.↗
NASA NTRS1976

Inferences from the dynamical history of Mercury's rotation

The history of Mercury's spin angular momentum is reviewed. It is shown that the current nonsynchronous but resonant spin and the nearly zero obliquity place almost no restrictions on the primordial spin state. The only exception comes about from a liquid core-solid mantle interaction which excludes a slow primordial spin concurrent with a large obliquity. The current occupancy of a final evolutionary spin state leads to the description of a scheme by which we can determine the extent of a currently liquid Mercurian core.

Peale, S. J.↗
NASA NTRS1976

Isotopic composition of nitrogen - Implications for the past history of Mars' atmosphere

Models are presented for the past history of nitrogen on Mars, based on Viking measurements showing that the atmosphere is enriched in N-15. The enrichment is attributed to selective escape, with fast atoms formed in the exosphere by electron impact dissociation of N2 and by dissociative recombination of N2(+). The initial partial pressure of N2 should have been at least as large as several millibars and could have been as large as 30 millibars if surface processes were to represent an important sink for atmospheric HNO2 and HNO3.

Mcelroy, M. B.↗