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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 1,225 records · Page 68
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Early history of the moon: Implications of U-Th-Pb and Rb-Sr systematics

Anorthosite 60015 contains the lowest initial Sr-87/Sr-86 ratio (0.69884 + or - 0.00004) yet reported for a lunar sample. The initial ratio is equal to that of the achondrite Angra dos Reis and slightly higher than the lowest measured Sr-87/Sr-86 ratio for an inclusion in the C3 carbonaceous chondrite Allende. The Pb-Pb ages of both Angra dos Reis and Allende are 4.62 x 10 to the 9th power years (4.62 billion years). Thus, the initial Sr-87/Sr-86 ratio found in lunar anorthosite 60015 strongly supports the hypothesis that the age of the moon is about 4.65 b.y. The U-238/Pb-204 value estimated for the source of the excess lead in orange soil 74220 is lower than the values estimated for the sources of KREEP (600-1000), high K (300-600) and low K (100-300) basalts.

Tatsumoto, M.↗
NASA NTRS1974

The exposure history of the Apollo 16 sites. An assessment based on methane and carbide measurements

Soils from eight stations at the Apollo 16 landing site have been analyzed for methane and carbide. These results, in conjunction with published data from photogeology, bulk chemistry, rare gases, primordial and radionuclides, and agglutinate abundances have been interpreted in terms of differing contributions from three components, North and South Ray crater ejecta and Cayley Plains material.

Pillinger, C. T.↗
NASA NTRS1974

Calculations of the moon's heat history at different concentrations of radioactive elements taking account of the material differentiation with melting

A mathematical procedure for analyzing the heat conductivity of the lunar surface is discussed. The solution is based on homogeneous and laminated moon models and considers the effects of radioactive elements conveyed to the lunar surface by melting. The various parameters which introduce uncertainties into the numerical analysis are identified. The application of data obtained from radio astronomy and from analyses of lunar samples returned by the Apollo flights is explained. Tables of data are included to show the types and amounts of radioactive materials which have been identified.

Arnatskaya, O. I.↗
NASA NTRS1974

Industrial noise control: Some case histories, volume 1

A collection of solutions to industrial noise problems is presented. Each problem is described in simple terms, with noise measurements where available, and the solution is given, often with explanatory figures. Where the solution rationale is not obvious, an explanatory paragraph is usually appended. As a preface to these solutions, a short exposition is provided of some of the guiding concepts used by noise control engineers in devising their solutions.

Hart, F. D.↗
NASA NTRS1975

A static air flow visualization method to obtain a time history of the lift-induced vortex and circulation

A recently proposed method of flow visualization was investigated at the National Aeronautics and Space Administration's Langley Research Center. This method of flow visualization is particularly applicable to the study of lift-induced wing tip vortices through which it is possible to record the entire life span of the vortex. To accomplish this, a vertical screen of smoke was produced perpendicular to the flight path and allowed to become stationary. A model was then driven through the screen of smoke producing the circular vortex motion made visible as the smoke was induced along the path taken by the flow and was recorded by highspeed motion pictures.

Patterson, J. C., Jr.↗
NASA NTRS1974

Electric propulsion - Past history and future prospects

Studies of feasibility and flight mechanics of electric propulsion systems began around 1946. Conceptual systems design started in 1954, experimental development in 1958; flight tests in 1964 and 1970 proved the functioning of electric thrusters in space. Further development of ion thruster systems has concentrated on bombardment ionization in the U.S., and on radiofrequency, bombardment, and surface-contact ionization in West Germany, Great Britain, France, and the USSR. Electrothermal, plasma, and colloid thruster development has been pursued in many countries. Electric thrusters were used successfully during past years for satellite attitude control, and for prime propulsion of the Soviet spacecraft Yantar. Further applications for attitude and position control of satellites are planned.

Stuhlinger, E.↗
NASA NTRS1974

Surface history of some Apollo 17 lunar soils

Cosmic ray track densities in Apollo 17 soil samples are used to infer surface exposure times of soils from a trench at Van Serg Crater, from on and near a boulder at Camelot Crater, and from the position of the heat flow and neutron flux experiments (the ALSEP site). The topmost 2 cm of soil at Van Serg was exposed for 11 m.y., the top cm at Camelot for 36 m.y. A layering chronology and average deposition rate are proposed for the trench. For all soils the median track densities imply predispositional irradiation in the top 15 cm of the lunar surface for times that were long compared with the actual residence in the stratigraphic positions from which the soils were collected. Van Serg crater is inferred to have been formed approximately 24 m.y. ago.

Fleischer, R. L.↗
NASA NTRS1974

Cosmic-ray exposure history at the Apollo 16 and other lunar sites - Lunar surface dynamics

Concordant Kr-81/Kr exposure ages for four station 11 breccias indicate an age of 50.3 plus or minus 0.8 m.y. for North Ray Crater. Ray structures visible from orbital photography suggest that stations 8 and 9 should contain a substantial amount of South Ray ejecta. Concordant Kr-81/Kr exposure ages at these sites indicate an age for South Ray Crater of 2.04 plus or minus 0.08 m.y. Surface effects show good general agreement with this young age, but discrepancies on a sample-by-sample basis seem to indicate that extensive presurface irradiations must have occurred.

Drozd, R. J.↗
NASA NTRS1975

Radiant coolers - Theory, flight histories, design comparisons and future applications

Radiant coolers have been developed for application to the cooling of infrared detectors aboard NASA earth observation systems and as part of the Defense Meteorological Satellite Program. The prime design constraints for these coolers are the location of the cooler aboard the satellite and the satellite orbit. Flight data from several coolers indicates that, in general, design temperatures are achieved. However, potential problems relative to the contamination of cold surfaces are also revealed by the data. A comparison among the various cooler designs and flight performances indicates design improvements that can minimize the contamination problem in the future.

Donohoe, M. J.↗
NASA NTRS1975

Weightlessness - A case history

A review of the average bodily systems functioning aboard Skylab II after 20 days of weightlessness is presented. Condition of eyes, ears, nose and throat, gastrointestinal tract, vestibular organs, cardiovascular system, musculoskeletal system, sleep, general appearance, skin, abdomen, and extremities is summarized. The general health of the crewmen is good, although there are some slight anomalies, such as weight loss, dry skin, nasal speech, and paresthesia of the soles of the feet.

Kerwin, J. P.↗
NASA NTRS1974

Electric propulsion - Past history and future prospects

Studies of feasibility and flight mechanics of electric propulsion systems began around 1946. Conceptual systems design started in 1954, experimental developments in 1958; flight tests in 1964 and 1970 proved the functioning of electric thrusters in space. Further development of ion thruster systems has concentrated on bombardment ionization in the U.S., and on radiofrequency, bombardment, and surface contact ionization in West Germany, Great Britain, France and Russia. Electrothermal, plasma, and colloid thruster development has been pursued in many contries. Electric thrusters were used successfully during past years for satellite attitude control, and for prime propulsion of the Russian spacecraft Yantar. Further applications for attitude and position control of satellites are planned. Studies are presently underway for solar electric missions to planets, planetary moons, comets, asteroids, and toward the sun, and also for missions in near-earth space involving transfer, servicing, and repair of orbiting spacecraft.

Stuhlinger, E.↗
NASA NTRS1974

Structural history of southeastern Mare Serenitatis and adjacent highlands

Deformational events are identified from Apollo 17 low-sun photographs of southern Mare Serenitatis and the adjacent Taurus-Littrow region. Analysis of the data indicates that the rate of deformation, including subsidence of the Serenitatis basin, has decreased through time as the crust increased in strength. Three main basalt sequences are found: one each at 3.8, 3.5, and 3.2 b.y. Wrinkle ridges began forming at about 2.5 b.y.; asymmetrical scarps also formed much later than the deformations.

Muehlberger, W. R.↗
NASA NTRS1974

Regolith history from cosmic-ray-produced nuclides

A model is given for regolith development by which the meteoroid impact parameters (time of last major impact, soil escape rate, and soil turnover depths) are determined from the Gd isotope data for the Apollo 15 and 16 drill stems. The time of the last major impact, cosmic-ray-produced-nuclide-clock reset time, at the Apollo 15 site is 0.6-1.3 aeon. The reset time at the Apollo 16 site is between 1.54 plus or minus 0.14 and 3.3-4.0 aeon. The average soil escape rate from the moon corresponding to the 1.54 plus or minus 0.14 aeon reset time is between 70 and 110 cm/aeon and corresponding to the 3.3 and 4.0 aeon reset time is between 36 and 56 cm/aeon. The soil turnover depth for the 1.54 plus or minus 0.14 aeon reset time is 250 cm and for the 3.3-4.0 aeon reset time is 750 cm. The Gd data restrict the change with time of the meteoroid flux during the past 1.4 aeon.

Fireman, E. L.↗
NASA NTRS1974

On the exposure history of the lunar regolith

The observed minimum and mean values of track densities in lunar grains are both found to exceed the values expected from exposure with redistribution by vertical mixing, and the percentage of the smaller grains showing very high track densities is too large by a factor of more than ten. Previous exposure of the material (in space before accretion onto the moon or in regions from which net migration has occurred) may be necessitated.

Gold, T.↗
NASA NTRS1974

Early active sun - Radiation history of distinct components in fines

Plagioclase feldspars were separated from lunar soil samples and their compositions were determined by electron-microprobe analysis followed by etching and track counting in an effort to find effects of early solar activity. The feldspars were assigned on this basis to three major lithologies: mare basalts, anorthositic rocks, and KREEP rock. The results are in sharp contrast to Poupeau et al.'s (1973) observations on track densities in plagioclase crystals in the Luna 16 soil: no evidence is found for an early active sun, although the evidence does not preclude this possibility, either.

Crozaz, G.↗
NASA NTRS1975

The early scientific history of the rocket-grenade experiment

In the decade, 1950 to 1960, some thirty sounding rockets carrying the grenade experiment were fired in the Arctic, at middle latitudes and in the equatorial western Pacific. The vertical distributions of temperatures and winds at different seasons and at different times of the day were measured. Although there were significant variations in the results from each of the sites, an outstanding feature was the uniformity with latitude of the seasonal variation of the wind field. Over the latitude-altitude ranges sampled, the winds were strong and from the west during the winter months; and weak and from the east during the summer months. The nature of the general circulation pattern in the mesosphere of the northern hemisphere was revealed by the measurements. Of particular interest were those measurements made at the seasonal turnovers because of the insight into the dynamics of this region they provided.

Stroud, W. G.↗