Implications of Jupiter's early contraction history for the composition of the Galilean satellites
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Pollack, J. B.↗
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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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Possible histories of the obliquity of Mercury
Possible evolutionary paths of the spin axis of Mercury are studied theoretically in terms of generalized Cassini's laws using the Hamiltonian approach. Three stable positions (Cassini states) of the spin axis are discerned. The Cassini states in which the spin axis remains fixed in the frame rotating with the orbit precession are extremes in the tide-free Hamiltonian under the condition of constant angular momentum. The stability of the 3/2 spin resonance for Mercury as a function of obliquity is discussed, and it is shown how control of the resonance is passed from one to another term in the averaged potential as the obliquity is increased with a corresponding loss of stability at each transfer. A sampling technique is used to infer the evolution due to tidal interaction. Two tidal models are used - one with a constant value of the specific dissipation function Q and the other with Q inversely proportional to frequency. An approximate analytic solution for precession trajectories very close to a Cassini state is developed.
Peale, S. J.↗
Evidence for an episode of crater obliteration intermediate in Martian history
It is shown that Mars experienced a brief episode of an increased obliteration rate contemporaneous with the formation of the cratered plains units. The obliteration rate during this episode was at least an order of magnitude greater than the preexisting rate. The obliteration rates prior to and after the event were identical within a factor of 3. Regional variations in the observed densities of degraded craters on the cratered terrain are shown to result from differences in the intensity of the obliteration rate during the event. The identification and characterization of the event are accomplished by using crater diameter-frequency distributions, not only for the total crater population but also for four morphological classes. Distributions are selected from 38 regions within the Martian equatorial latitudes.
Jones, K. L.↗
Lunar orbiter management: Case history
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Costello, T. R.↗
Clues in the rare gas isotopes to early solar system history
Rare gases in meteorites and lunar samples are discussed stimulating the discovery of the solar wind. Radioactive isotopes are examined, making a correlation to the origin of the solar system. It is shown that the heights of the peaks above the horizontal lines represent the spectrum of the fissiogenic sample. Nuclear tracks of iodine, xenon, and plutonium detected in lunar rocks are also explained.
Reynolds, J. H.↗
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.↗
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.↗
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.↗
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.↗
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.↗
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.↗
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.↗
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.↗
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.↗
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.↗
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.↗
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.↗
Glass-coated soil breccia 15205 - Selenologic history and petrologic constraints on the nature of its source region
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Dymek, R. F.↗