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  • Other Sources  (1,213)
  • SPACE SCIENCES  (858)
  • SPACE RADIATION  (355)
  • General Chemistry
  • Cell & Developmental Biology
  • 1970-1974  (1,213)
  • 1974  (1,213)
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  • 1970-1974  (1,213)
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  • 1
    Publication Date: 2006-04-02
    Description: The Pontryagin Maximum Principle is used to formulate the problem of finding optimum atmospheric vehicular reentry trajectories. The optimization problem is that of minimizing an integral which is a function of the state and control variables. The vehicle's motion is assumed to be influenced by a gravitational force and an aerodynamic force. The problem is formulated and the necessary equations are developed simultaneously for three sets of Euler angles. Computational procedures are suggested so that numerical trajectories may be generated.
    Keywords: SPACE SCIENCES
    Type: Multivariant Function Model Generation; 93 p
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  • 2
    Publication Date: 2006-04-02
    Description: The problem of predicting the minimum fuel trajectory for a six degree of freedom vehicle which has a motion characterized by the first order differential equations of translational and rotational dynamics is considered. The thrust direction and center of gravity of the vehicle are assumed to be fixed with respect to the vehicle. Thrust magnitude and the control moment are used as control variables and appear linearly in the equation of motion. Pontryagin's Maximum Principle is used to solve the variational problem. With this formulation, the extremal controls are bang-bang with the exception of the singular case.
    Keywords: SPACE SCIENCES
    Type: Multivariant Function Model Generation; 18 p
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  • 3
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    In:  CASI
    Publication Date: 2006-01-11
    Description: Juridical aspects of space flights and international law are elaborated. Considered are manned orbital space stations, as well as lunar or planetary bases and the international exploration of extraterrestrial resources.
    Keywords: SPACE SCIENCES
    Type: Inhabited Space, Pt. 2 (NASA-TT-F-820); p 170-175
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  • 4
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    In:  CASI
    Publication Date: 2006-01-11
    Description: It is shown that ionic relativistic rockets are most suitable for carrying out interstellar flights in comparison with photonic rockets or nuclear interstellar aircraft. Slow interstellar flights are much more probable than fast flights.
    Keywords: SPACE SCIENCES
    Type: Inhabited Space, Pt. 2 (NASA-TT-F-820); p 154-160
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  • 5
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    Publication Date: 2006-01-11
    Description: The probability of radio interchange with extraterrestrial civilizations is discussed. Difficulties constitute absorption, scattering, and dispersion of signals by the rarified interstellar medium as well as the deciphering of received signals and convergence of semantic concept. A cybernetic approach considers searching for signals that develop from astroengineering activities of extraterrestrial civilizations.
    Keywords: SPACE SCIENCES
    Type: Inhabited Space, Pt. 2 (NASA-TT-F-820); p 83-110
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  • 6
    Publication Date: 2006-01-11
    Description: The numerous planetary systems in our galaxy appear to a high degree of probability to contain some planets with a biosphere similar to earth' environment. The possibility of communicating with those extraterrestrial alien planetary civilizations centers on the high level of technological development that is required to overcome the problem of distance. It is conceivable that advanced civilizations can produce energy at a level of 10 to the 43rd power erg/year and that an artificial biosphere can be developed within the limits of 10 to the 22nd power to 10 to the 23rd power cm.
    Keywords: SPACE SCIENCES
    Type: Inhabited Space, Pt. 2 (NASA-TT-F-820); p 67-78
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  • 7
    Publication Date: 2006-01-11
    Description: Possible criteria characterizing extraterrestrial civilizations and their detection are: (1) deduction of their existence by evaluating astronomical prerequisites for the development of life in remote planetary systems; (2) detection and communication with extraterrestrial civilizations; and (3) the problem of language and content of information in transmitted signals.
    Keywords: SPACE SCIENCES
    Type: Inhabited Space, Pt. 2 (NASA-TT-F-820); p 62-66
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  • 8
    Publication Date: 2006-01-11
    Description: A computer program for computing the performance trajectory of spacecraft was developed. An analytical study of a minimum fuel flight for high speed aircraft was conducted. The computer program to compute a minimum time reentry into the atmosphere for an Apollo-type capsule is presented. A technical summary of the minimum fuel problem is provided.
    Keywords: SPACE SCIENCES
    Type: Multivariant Function Model Generation; 34 p
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  • 9
    Publication Date: 2006-01-11
    Description: An urgent problem in space materials science is simulating the interaction of vacuum ultraviolet (VUV) of solar emission with solids in space conditions, that is, producing a light source with a distribution that approximates the distribution of solar energy. Information is presented on the distribution of the energy flux of VUV of solar radiation. Requirements that must be satisfied by the VUV source used for space materials science are formulated, and a critical evaluation is given of the possibilities of using existing sources for space materials science. From this evaluation it was established that none of the sources of VUV satisfies the specific requirements imposed on the simulator of solar radiation. A solution to the problem was found to be in the development of a new type of source based on exciting a supersonic gas jet flowing into vacuum with a sense electron beam. A description of this gas-jet source, along with its spectral and operation characteristics, is presented.
    Keywords: SPACE RADIATION
    Type: Space Res. in the Ukraine, No. 3 (NASA-TT-F-15537); p 102-123
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  • 10
    Publication Date: 2006-01-11
    Description: The results are presented of an investigation of the effect of small flares, scale divisions 1 and 1(+), in the neutron component of secondary cosmic radiation from the data of neutron supermonitors at the stations of Kiev, Bukhta Tiksi, and Deep River. It is shown that flares of scale divisions 1 and 1(+) are accompanied by an effect in the neutron component amounting to about 0.4%. A mechanism is presented for calculating the outflow of particles accelerated in small flares, owing to diffusion across the magnetic field of a trap.
    Keywords: SPACE RADIATION
    Type: Space Res. in the Ukraine, No. 3 (NASA-TT-F-15537); p 77-85
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  • 11
    Publication Date: 2006-01-11
    Description: Results are presented from a study of the region of anomalous cosmic radiation in the area of the Brazilian magnetic anomaly at the altitudes 250-500 km, using data measurements taken on the Kosmos-225 satellite (14-29 June 1968). The existence of a stable intensity anomaly discovered in the experiments on the second and third Soviet spacecraft-satellites is confirmed. The total vector of the geomagnetic field at different altitudes was compared with isoline maps. An altitude profile of the South Atlantic anomaly of radiation intensity was obtained, using data from the same instrument. The nature of the anomalies in cosmic radiation intensity over the regions of negative magnetic anomalies is discussed.
    Keywords: SPACE RADIATION
    Type: Space Res. in the Ukraine, No. 3 (NASA-TT-F-15537); p 86-94
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  • 12
    Publication Date: 2006-01-11
    Description: Using the Fokker-Planck equation, an examination is made of the acceleration of charged particles by fluctuational electric fields caused by the propagation of intense radio emission in the long-wave range. Correlation functions of electric fields near the boundary of plasma instability were computed. The interaction of charged particles with these fields is examined. It is shown that due to the interaction of particles with fluctuational fields, solar cosmic rays can be accelerated to energies of E=100 to 1000 MeV.
    Keywords: SPACE RADIATION
    Type: Space Res. in the Ukraine, No. 3 (NASA-TT-F-15537); p 69-76
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  • 13
    Publication Date: 2006-01-11
    Description: A catalogue of flare activity was compiled during 1957-1967 (the solar activity cycle). By comparing all reliable SC during this period with chromospheric flares, the following conclusions are drawn; (1) There is no statistically significant correlation between SC and chromospheric flares. (2) The assumption that a shock wave propagates throughout the entire hemisphere is unjustified and contradicts the fact of recurrence of SC. (3) A statistically significant correlation was established between SC and chromospheric flares, that is, a relationship between a SC and the moment that a flare active region transits the Central Meridian. (4) SC are caused by shock waves or tangential discontinuities formed at the western boundary of the quasisteady directed corpuscular flux or at the boundary between sectors.
    Keywords: SPACE RADIATION
    Type: Space Res. in the Ukraine, No. 3 (NASA-TT-F-15537); p 61-68
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  • 14
    Publication Date: 2006-01-11
    Description: Based on world data for the period 1 January 1955 to 31 December 1968, reports of 894 SC cases and 2152 SI cases were collected. A study was made of the diurnal and seasonal trends in the incidence of their appearances. It is shown that the diurnal trend is pronounced for all events with a maximum at (06-8)h universal time. The diurnal trend for SC in the resultant period is more pronounced. The seasonal trend in incidence of appearances of SC and SI is absent. Thus, geomagnetic disturbances of both SC and SI are monitored by world time. These results lead to the conclusion that the presence or absence of SC and SI during geomagnetic storms is determined not only by the nature of the corpuscular flux, the presence of shock waves and tangential discontinuities, but also by purely terrestrial conditions.
    Keywords: SPACE SCIENCES
    Type: in its Space Res. in the Ukraine, No. 3 (NASA-TT-F-15537); p 54-68
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  • 15
    Publication Date: 2006-01-11
    Description: The results of observations of the moon and planets are presented and include: (1) data on the discovery of high porosity values and the broken terrain of the lunar surface, and (2) data on the coloration of lunar rocks. A comparative description is given of data obtained by astronomical and by satellite observations.
    Keywords: SPACE SCIENCES
    Type: Space Res. in the Ukraine, No. 3 (NASA-TT-F-15537); p 29-43
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  • 16
    Publication Date: 2006-01-11
    Description: The radiophysical studies reported consist of direct measurements of certain effects induced in the propagation of radio waves from space objects. From measured effects and from data on the motion and position of space objects, physical parameters of the medium and bodies are determined.
    Keywords: SPACE SCIENCES
    Type: Space Res. in the Ukraine, No. 3 (NASA-TT-F-15537); p 1-28
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  • 17
    Publication Date: 2006-01-11
    Description: Volcanic tuff from the Artik deposit in Armenia is especially suited for experiments in simulating lunar soil, with the aid of compaction by vibration.
    Keywords: SPACE SCIENCES
    Type: Current Concepts Regarding the Moon (NASA-TT-F-766); p 186-191
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  • 18
    Publication Date: 2006-01-11
    Description: Study of evaporation, condensation and sputtering on the moon can provide information on the same processes on other planets, and reveal details of the formation of the lunar regolith. Simulation methods include vacuum evaporation, laser evaporation, and bubbling gas through melts.
    Keywords: SPACE SCIENCES
    Type: Current Concepts Regarding the Moon (NASA-TT-F-766); p 155-185
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  • 19
    Publication Date: 2006-01-11
    Description: Compilation and labelling of geological and morphological charts on a scale of 1:1,000,000 are discussed with emphasis on the regions of Maria Tranquilitatis, Crisium, Fecunditatis, Humorum and Nukium as well as certain prominent craters.
    Keywords: SPACE SCIENCES
    Type: Current Concepts Regarding the Moon (NASA-TT-F-766); p 97-138
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  • 20
    Publication Date: 2006-01-11
    Description: The intrinsic thermal radiation of the moon is an indicator of the temperature regime of the lunar surface, its physical conditions and structure, as indicated by data from Luna 9 and 13, as well as Surveyor 1 to 7.
    Keywords: SPACE SCIENCES
    Type: Current Concepts Regarding the Moon (NASA-TT-F-766); p 63-96
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  • 21
    Publication Date: 2006-01-11
    Description: The results are described of geological and morphological interpretation of large-scale photographs of the surface of lunar maria. A morphological classification is proposed for small craters. It is shown that the classification of a crater in a given morphological category, reflecting the degree of its morphological maturity, is determined by the age of the given crater. A check on the nature of distribution of small craters, as done on the basis of the nearest neighbor method, show that the distribution is governed by a near-random law. It is found that variations of the probability density function for the craters conform to a normal distribution law. An empirical relation is found for the coefficient of variation as a function of crater diameter and the dimensions of the area on which the counts are made. The rockfalls near craters of various morphological classes are described.
    Keywords: SPACE SCIENCES
    Type: Current Concepts Regarding the Moon (NASA-TT-F-766); p 25-62
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  • 22
    Publication Date: 2011-08-16
    Description: A measurement, using the magnetic emulsion spectrometer system, of the differential rigidity spectrum of Z greater than or equal to 3 nuclei of the galactic cosmic radiation is presented. The system was flown on Aug. 22, 1969, from Palestine, Texas. The instrument floated above 125,000 feet for eight hours. The data in the rigidity range 8-285 GV can be represented by a power-law spectrum in rigidity, J(rho) = A rho to the minus gamma power, with the exponent gamma = 2.6 plus or minus 0.10. The spectrum in the range 15-285 GV is also described by the same exponent, gamma = 2.6 plus or minus 0.25. The data below 8 GV cannot be described by the same power law without invoking solar modulation. A set of nonunique parameters for modulation are given. Upper limit for the fraction of antimatter in the rigidity range 4-125 GV is .005 with 95% confidence limit.
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal; 192; Sept. 15
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  • 23
    Publication Date: 2011-08-16
    Description: Data from SAS-2 on the galactic gamma ray line flux as a function of longitude is examined. It is shown that the gamma ray emissivity varies with galactocentric distance and is about an order of magnitude higher than the local value in a toroidal region between 4 and 5 kpc from the galactic center. This enhancement is accounted for in part by first-order Fermi acceleration, compression, and trapping of cosmic rays consistent with present ideas of galactic dynamics and galactic structure theory. Calculations indicate that cosmic rays in the 4 to 5 kpc region are trapped and accelerated over a mean time of the order of a few million years or about 2 to 4 times the assumed trapping time in the solar region of the galaxy on the assumption that only an increased cosmic ray flux is responsible for the observed emission. Cosmic ray nucleons, cosmic ray electrons, and ionized hydrogen gas were found to have a strikingly similar distribution in the galaxy according to both the observational data and the theoretical model discussed.
    Keywords: SPACE RADIATION
    Type: ESRO The Context and Status of Gamma Ray Astronomy; p 241-248
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  • 24
    Publication Date: 2011-08-16
    Description: Compact gamma ray sources centered on the Crab nebula and the Vela X supernova remnant are considered. An excess in the galactic radiation was observed in both regions. Data indicate that a large fraction of this flux is pulsed. The excess from the Vela region could reflect either a large-scale galactic feature, such as a superposition of spiral arm segments, or it could be associated with the Vela supernova remnant. Low-energy gamma ray bursts were observed in the SAS-2 anticoincidence shielding.
    Keywords: SPACE RADIATION
    Type: ESRO The Context and Status of Gamma Ray Astronomy; p 273-277
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  • 25
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    Publication Date: 2011-08-16
    Description: The infrared spectral range extends approximately from 1 micron to 1000 microns. Observations in infrared astronomy are made with the aid of ground-based telescopes and telescopes flown in aircraft, balloons, or rockets. Advantages and drawbacks of infrared studies conducted by different approaches are discussed. Infrared astronomers are looking forward to observations made from orbiting spacecraft. Present plans call for placing a large telescope aboard the Space Shuttle Orbiter for short missions lasting from seven days to three weeks several times a year. However, the occurrence of a pollution of the spacecraft environment by dust particles and gases coming from the spacecraft might present a problem for the observations. Possible approaches for solving this problem are discussed.
    Keywords: SPACE SCIENCES
    Type: Astronautics and Aeronautics; 12; Oct. 197
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  • 26
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    Publication Date: 2011-08-16
    Description: Data on galactic X-ray sources from rocket and balloon experiments and the UHURU satellite are reported. The outline emphasizes general discrete source models and begins with some a priori considerations about X-ray emission mechanisms and their applicability, after which contemporary data are interpreted according to these models. Topics covered include the production of X-rays by various mechanisms, source regimes, observational parameters, stellar distributions, individual stars, flare stars, supernovae and pulsars, the Crab nebula, old and young remnants, binary systems, and others.
    Keywords: SPACE SCIENCES
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  • 27
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    Publication Date: 2011-08-16
    Description: The published literature on cosmic electrons is summarized. The primary and secondary sources of cosmic electrons are discussed, and the propagation of the electrons in the interstellar medium is studied with respect to energy loss mechanisms, age distributions, and spectral modifications during flight. Various portions of the electron and positron spectra are then considered in relation to problems of astrophysics. New information is presented on such topics as the origin of low-energy positrons, the decay kinematics of the pi-mu-e process, the application of age distributions for nuclear cosmic rays to cosmic electrons, and the possibility of nonidentical sources for cosmic electrons and protons.
    Keywords: SPACE RADIATION
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  • 28
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    Publication Date: 2011-08-16
    Description: The origins, generation, detection, and interpretation of radio signals are discussed for signals with an assumed random polarization. After defining the basic parameters, the discussion moves to such topics as synchrotron radiation, plasma effects, changes in the electron energy spectrum in the radiating regions, energy loss to ionization, bremsstrahlung, radio astronomical observations of high-energy particles, emission by energetic particles, observation of supernova remnants and pulsars, galactic background continuum radiation, and others.
    Keywords: SPACE SCIENCES
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  • 29
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    Publication Date: 2011-08-16
    Description: Emission from Jupiter has been observed by the IMP-6 spacecraft at 19 frequencies between 600 and 9900 kHz covering the period from April 1971 to October 1972. The Jovian bursts were identified in the IMP-6 data through the phase of the observed modulated signal detected from the spinning dipole antenna. Initial data reduction has isolated 177 events over a span of 500 days. These events persisted over a period between 1 and 60 min. Of these events at least 48 occurred during times in which Jupiter emission was being observed at either 16.7 or 22.2 MHz by ground-based instruments of the Goddard Space Flight Center Jupiter monitoring system. Large bursts were detectable from 9900 kHz down to 600 kHz, while smaller bursts ranged down to 1030 kHz.-
    Keywords: SPACE SCIENCES
    Type: Astrophysical Journal; 192; Sept. 1
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  • 30
    Publication Date: 2011-08-16
    Description: The meteoroid penetration detectors on the Pioneer 10 spacecraft recorded 67 meteoroid penetrations through the 25-micron stainless steel test material while the spacecraft was between 1.0 and 5.1 AU. Ten of these penetrations occurred during the encounter with Jupiter. The cumulative spatial density of meteoroids with masses greater than 2 nanograms has been calculated from these data for interplanetary space and for the near-Jupiter space. The spatial density is found to be essentially constant in interplanetary space between 1 and 5 AU, approximately 1 meteoroid per cubic km, and 1-2 orders of magnitude greater near Jupiter. There was no increase in the spatial density of meteoroids in the asteroid belt and hence no evidence that there is a significant asteroidal component of 2-nanogram meteoroids. It is uncertain whether the meteoroids detected near Jupiter were in orbit about Jupiter or were gravitationally focused toward the planet from solar orbits.
    Keywords: SPACE SCIENCES
    Type: Journal of Geophysical Research; 79; Sept. 1
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  • 31
    Publication Date: 2011-08-16
    Description: The major features of the propagation of flare particles in the interplanetary medium are discussed in terms of the classic well-behaved flare having unique impulsive injection and a smooth time profile. Topics include flare events, their frequency of occurrence, development of a typical event, energy spectra, proton and electron types, charge and isotopic composition, solar flares and particle accelerations, radio and X-ray observations, the Fermi mechanism, the betatron mechanism, acceleration models, plasma instabilities, two-stage acceleration, propagation mechanisms, the anisotropic stage, the diffusive stage, and the convection and energy loss stage.
    Keywords: SPACE RADIATION
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  • 32
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    Publication Date: 2011-08-16
    Description: The present work provides an outline of the history of the efforts to map the topography of the surface of the moon, from the days of pre-telescopic astronomy to the present. The first part of the book covers the time span from 1600 to 1960 and reproduces numerous examples of this early, earth-based selenographic work. The manned lunar missions in the 1960's revolutionized the science of lunar mapping with their high-resolution, close-range photography of the moon. In 1959, a comprehensive lunar mapping program was initiated by two DOD mapping agencies - the U.S. Air Force Aeronautical Chart and Information Center (ACIC) and the U.S. Army Map Service (AMS). In the course of this program, the cause of lunar mapping enlisted for the first time the services of professional cartographers; the outcome of their efforts speedily relegated all previous work into absolescence. The methods and results of this work are described, and the underlying principles of physical selenodesy are set forth, including the definition of lunar coordinates and the methods for a determination of three-dimensional coordinates of lunar features. A section is included on lunar mapping in the U.S.S.R.
    Keywords: SPACE SCIENCES
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  • 33
    Publication Date: 2011-08-16
    Description: The critical mass for stability against radial pulsations in rotating, homogeneous main-sequence stars is found to be greater than in the case of no rotation. Analytic and detailed numerical models show that the critical mass rises steeply with increasing concentration of angular momentum to the center of the star. For uniform rotation near breakup velocity at the star's equator the critical mass is about 850 solar masses if an electron-scattering opacity is used, or about 5000 solar masses if the opacities of Cox and Stewart are used. For nonuniform rotation with a constant ratio of centrifugal force to gravity in the star, the critical mass becomes 'infinite' long before breakup velocity is attained. The relevance of the present results to several observational problems is noted.
    Keywords: SPACE SCIENCES
    Type: Astrophysical Journal; 192; Aug. 15
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  • 34
    Publication Date: 2011-08-16
    Keywords: SPACE SCIENCES
    Type: vol. 28; June 197
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  • 35
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    Publication Date: 2011-08-16
    Description: In the plot of asteroids considered the mass density is substituted for the number density. This approach provides a better definition of the limits of the main belt, and demonstrates more clearly that the asteroids, like the Saturnian rings, have condensed from partially corotating plasma. A diagram shows that the whole main belt is located below 2/3 of Jupiter's orbit. This means that the main belt asteroids may have been derived from condensation which took place inside Jupiter's orbit.
    Keywords: SPACE SCIENCES
    Type: Nature; 250; Aug. 23
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  • 36
    Publication Date: 2011-08-16
    Description: Review of the initial studies that define a challenging Mariner Jupiter Orbiter mission. Elegant and precise astrodynamics are shown to make possible a bravura examination of the entire Jovian system with two Mariner-class spacecraft to be launched in 1981. This mission is expected to advance considerably our understanding of the origin and evolution of the solar system.
    Keywords: SPACE SCIENCES
    Type: Astronautics and Aeronautics; 12; Sept
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  • 37
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    Publication Date: 2011-08-16
    Description: It is pointed out that the lunar magnetometer experiment has made important contributions to studies of the lunar interior. Numerical inversions of the lunar electromagnetic response have been carried out, taking into account a void region behind the moon. The amplitude of the transfer function of an eight-layer model is considered along with a model of the temperature distribution inside the moon and the amplitude of the transfer function of a semiconductor lunar model.
    Keywords: SPACE SCIENCES
    Type: Nature; 250; Aug. 16
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  • 38
    Publication Date: 2011-08-16
    Keywords: SPACE SCIENCES
    Type: British Interplanetary Society; vol. 27
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  • 39
    Publication Date: 2011-08-16
    Description: A Hylleraas bound-state wave function and 1s-2s-2p close-coupling continuum wave functions are used to calculate the absorption coefficient for the free-bound transition of H(1s) + e + quantum to a H anion in (2p2,3Pe) and the differential emission rate for the inverse process. The absorption and emission spectral maximum is found to be at a photon wavelength of 1219.5 A, an improvement of 2 A on other calculations. This free-bound absorption process appears to be a significant source of continuous ultraviolet opacity.
    Keywords: SPACE SCIENCES
    Type: Astrophysical Journal; 191; Aug. 1
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  • 40
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    Publication Date: 2011-08-16
    Description: The microscopic physics of the thermonuclear runaway in highly degenerate carbon-oxygen cores is investigated to determine if and how a detonation wave is generated. An expression for the electron-ion relaxation time is derived under the assumption of large degeneracy and extreme relativity of the electrons in a two-temperature plasma. Since the nuclear burning time proves to be several orders of magnitude shorter than the relaxation time, it is concluded that in studying the structure of the detonation wave the electrons and ions must be treated as separate fluids.
    Keywords: SPACE SCIENCES
    Type: Astrophysical Journal; 191; Aug. 1
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  • 41
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    Publication Date: 2011-08-16
    Description: Rate constants for the rotational excitation of HCN by collisions with He atoms at temperatures below 100 K were computed from first principles and are presented in tabular form. The potential energy surface was obtained by using the uniform electron gas model of Gordon and Kim (1972) and then joined smoothly to the asymptotic long-range perturbation theory potential valid at large separations. Quantum close-coupling theory was used to analyze the collision dynamics. Individual rates are believed to be accurate to within 50% above 30 K and within a factor of two below 20 K. The results should be extendable to excitation by collision with H2 and may therefore be of value in the study of interstellar clouds.
    Keywords: SPACE SCIENCES
    Type: Astrophysical Journal; 191; Aug. 1
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  • 42
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    Publication Date: 2011-08-16
    Description: Sweet (1956, 1958) proposed a mechanism for the rapid, steady-state dissipation of a magnetic field in a resistive plasma. It is shown that Sweet's mechanism operates in the interplanetary medium near 1 AU in structures which Burlaga and Ness (1968) have identified and called D-sheets. The basic equations are considered of a specific mathematical model provided by Parker (1963) for the case of antiparallel fields and incompressible flow. The theoretical conclusions are related to interplanetary observations.
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal; 191; Aug. 1
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  • 43
    Publication Date: 2011-08-16
    Description: The radio spectral data of OH471 and OQ172 are shown in a graph along with decompositions of the spectra into canonical self-absorbed synchrotron components. The minimum number of canonical components consistent with the data is used. Theoretically expected angular radii and time scales are presented in a table. The estimation of the angular size of a compact radio source with known spectral form rests upon the establishment of its maximum brightness temperature.
    Keywords: SPACE SCIENCES
    Type: Nature; 250; Aug. 9
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  • 44
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    Publication Date: 2011-08-16
    Description: Ozone co-appears with the clouds of the polar hood in the winter hemisphere of Mars, but each is variable from day to day and location to location. Both the appearance of ozone and the polar hood clouds correlate with the temperature of the atmosphere which varies from day to day and location to location. A cold, clean, dry atmosphere is conducive to the formation of ozone.
    Keywords: SPACE SCIENCES
    Type: Icarus; 22; June 197
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  • 45
    Publication Date: 2011-08-16
    Description: An ultraviolet spectral probe for a hydrogen-rich planetary atmosphere, such as that of Jupiter, is suggested, utilizing discrete lines in the H2(+) 2p pi u - /s sigma g electronic transition. For the Jovian atmosphere, the dominant mechanism for exciting H2(+) to its 2p pi u state appears to be photoexcitation, principally through absorption of the solar Lyman-alpha line. The critical role of corrections to the Born-Oppenheimer approximation in the use of an H2(+) probe is discussed.
    Keywords: SPACE SCIENCES
    Type: Icarus; 22; June 197
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  • 46
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    Publication Date: 2011-08-16
    Description: Models of the giant planets were constructed based on the assumption that the hydrogen to helium ratio is solar in these planets. This assumption, together with arguments about the condensation sequence in the primitive solar nebula, yields models with a central core of rock and possibly ice surrounded by an envelope of hydrogen, helium, methane, ammonia, and water. These last three volatiles many be individually enhanced due to condensation at the period of core formation. Jupiter was found to have a core of about 40 earth masses and a water enhancement in the atmosphere of about 7.5 times the solar value. Saturn was found to have a core of 20 earth masses and a water enhancement in the atmosphere of about 25 times the solar value. Rock plus ice constitute 75-85% of the mass of Uranus and Neptune.
    Keywords: SPACE SCIENCES
    Type: Icarus; 22; June 197
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  • 47
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    Publication Date: 2011-08-16
    Description: Tidal fission of both impacting and orbiting linear elastic solid bodies based on Kelvin's theory of earth tides is considered. It is shown that there can be more than one mutually exclusive modes of fracture - the particular mode in which a body fractures depending on its size and strength. The analysis gives a vivid picture of the propagation of the fracture with a decreasing distance from the planet. Expressions for the initiation and completion of fracture are obtained which are displayed graphically for a rigid body. The effect of elasticity on the breakup altitude is discussed. For orbiting solid bodies, the study gives the upper limit of the breakup altitude as 0.38R (where R is the radius of planet), which is much less than the value 1.44R used for such bodies in the past. The results presented include a previously given theory by Sekiguchi as a part. For the special case of a liquid body, comparison is made with Roche's calculation and the difference explained.
    Keywords: SPACE SCIENCES
    Type: Astrophysical Journal; 191; July 15
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  • 48
    Publication Date: 2011-08-16
    Description: Recent data from SAS-2 on the galactic gamma-ray line flux as a function of longitude reveal a broad maximum in the gamma-ray intensity in the longitude region less than or equal to 30 deg. These data, when unfolded, imply that the low-energy (1 to 10 GeV) galactic cosmic-ray flux varies with galactocentric distance and is about an order of magnitude higher than the local value in a toroidal region between 4 and 5 kpc from the galactic center. It is further shown that this enhancement can be plausibly accounted for by first-order Fermi acceleration, compression, and trapping of cosmic rays consistent with present ideas of galactic dynamics and galactic structure theory. Calculations indicate that cosmic rays in the 4- to 5-kpc region are trapped and accelerated over a mean time of the order of a few million years or about 2 to 4 times the assumed trapping time in the solar region of the Galaxy.
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal; 191; July 15
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  • 49
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    Publication Date: 2011-08-16
    Description: Development of a mechanism explaining the internal source of energy of comet outbursts. A mechanism is proposed which automatically provides a source of particulate matter which creates a huge surface area which contains a substantial percentage of amorphous ice, so that the phase transition of the amorphous ice to a cubic structure provides a release of energy which may be responsible for the outbursts observed in many comets. In addition, the volume into which the transition can propagate is estimated for a spherical comet with a radius of 5 km.
    Keywords: SPACE SCIENCES
    Type: Nature; 250; July 26
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  • 50
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    Publication Date: 2011-08-16
    Description: It is suggested that the apparent lag of Jupiter's mean rotation rate in extratropical latitudes (System II) behind the rotation rate of Jupiter's radio emissions (System III) is caused by the difference between phase speeds and true speeds in extratropical latitudes. An estimate of the difference based on the formula for the phase speed of Rossby waves agrees with the difference calculated from the two rotation rates.
    Keywords: SPACE SCIENCES
    Type: Journal of the Atmospheric Sciences; 31; July 197
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  • 51
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    Publication Date: 2011-08-16
    Description: Consideration of the origin of the absorption lines in QSOs with observed absolute redshifts much less than the empirical values. As a possible alternative to the plasmoid mechanism for decreasing the relatively large possible macroscopic or bulk motions in QSO clouds, it is shown that certain large relative bulk motions in QSO clouds can be dissipated without the presence of strong magnetic fields and without large adiabatic expansions. The essence of the argument is that a cloud with convergent internal velocities can coalesce inelastically, because the internal kinetic energy can be dissipated and radiated away. There are thus indications that observed QSO absorption clouds may have their origin in clouds with internal velocities which are convergent.
    Keywords: SPACE RADIATION
    Type: Nature; 250; July 26
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  • 52
    Publication Date: 2011-08-16
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal; 191; July 1
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  • 53
    Publication Date: 2011-08-16
    Keywords: SPACE SCIENCES
    Type: Astrophysical Journal; 191; July 1
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  • 54
    Publication Date: 2011-08-16
    Keywords: SPACE RADIATION
    Type: Solar Physics; 36; June 197
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  • 55
    Publication Date: 2011-08-16
    Description: Studies of the 1.9-A line produced by highly ionized iron during a solar flare indicate that this emission occurs under conditions approaching a steady-state ionization equilibrium. Time-dependent and steady-state ionization equilibrium values are used for calculation of 1.9 A line fluxes per unit flare emission. The results are compared with those obtained by observations of some four solar flares, showing that the calculations from time-dependent equilibrium values approximate the observed line flux values with the same accuracy as the calculations from steady-state equilibrium values only when the electron densities are equal to or greater than 10 billion per cu cm.
    Keywords: SPACE RADIATION
    Type: Solar Physics; 36; June 197
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  • 56
    Publication Date: 2011-08-16
    Description: Using the observed data for metric and hectometric type III radio bursts, the dependence of burst characteristics on the solar longitude has been examined over a wide frequency range. It is found that there exists and east-west asymmetry for the extension of metric type III bursts into the hectometric wavelength range. In particular, hectometric bursts are rarely observed for solar flares associated with metric bursts east of 60 E solar longitude. Furthermore, for east longitudes, the low-frequency radio observations show a large dispersion in drift time interval.
    Keywords: SPACE RADIATION
    Type: Solar Physics; 36; May 1974
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  • 57
    Publication Date: 2011-08-16
    Description: Calculation of the 2.2-MeV gamma-ray line intensity from the sun using a Monte Carlo method for neutron propagation in the solar atmosphere. Detailed results are provided concerning the total gamma-ray yield per neutron and the time profile of the 2.2-MeV line from an instantaneous and monoenergetic neutron source. The parameters which have the most significant effects on the line intensity are the energies of the neutrons, the position of the neutron source on the sun, and the abundance of He-3 in the photosphere. For an isotropic neutron source which is not too close to the limb of the sun, the gamma-ray yield is between about 0.02 to 0.2 photons per neutron, provided that the neutron energies are in the range from 1 to 100 MeV and the ratio He-3/H is less than about .00005.
    Keywords: SPACE SCIENCES
    Type: Solar Physics; 36; May 1974
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  • 58
    Publication Date: 2011-08-16
    Description: Expected wavelengths and intensities are computed for 1s2l-1snl prime transitions in helium-like ions of the abundant elements from oxygen to iron under coronal conditions. Probable observations of some of these lines in the spectra of solar flares are discussed, and attention is called to a possible reversal of singlet and triplet intensities as compared to laboratory observations.
    Keywords: SPACE RADIATION
    Type: Solar Physics; 36; May 1974
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  • 59
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    Publication Date: 2011-08-16
    Description: Review of the currently available knowledge on Titan's atmosphere, based on the report of the 1973 Titan Atmosphere Workshop. The atmosphere composition, clouds, haze, and thermal structure are discussed, along with the photochemistry, escape, and recycling of the atmosphere.
    Keywords: SPACE SCIENCES
    Type: Icarus; 22; May 1974
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  • 60
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    Publication Date: 2011-08-16
    Description: The frequency dependence of the parameters of interstellar scattering between 837 and 8085 MHz for the Vela pulsar are consistent with thin-screen models of strong scattering. The magnitudes of the parameters indicate an anomalous turbulence along the path when they are compared with results for other pulsars with comparable column densities of free electrons in the line of sight. This anomaly is due presumably to the Gum Nebula. The decorrelation frequency, appropriately defined, is related to the pulse broadening time by 2 pi as predicted theoretically.
    Keywords: SPACE SCIENCES
    Type: Astrophysical Journal; 190; June 15
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  • 61
    Publication Date: 2011-08-16
    Description: Radiometric measurements of Phobos at 10 and 20 microns show that the surface is covered by a material whose conductivity is extremely low, around .000001 cal per cm per sec per deg K. It is concluded that Phobos is covered with a layer of dust at least 1 mm thick.
    Keywords: SPACE SCIENCES
    Type: Astrophysical Journal; 190; June 1
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  • 62
    Publication Date: 2011-08-16
    Description: The imaging photopolarimeter experiment aboard the Pioneer 10 spacecraft produced two-dimensional maps of intensity and polarization in red and blue light at high resolution during flyby of Jupiter in December 1973. The present article describes cloud forms seen in the equatorial zone and compares them with rotational periods as a function of latitude derived from earth-based observations of features on Jupiter. A striking new feature consists of a bright, well-defined nucleus in the equatorial zone, with a plume apparently drawn out from the core of the nucleus.
    Keywords: SPACE SCIENCES
    Type: Science; 184; June 21
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  • 63
    Publication Date: 2011-08-16
    Description: For the case of homogeneous, isotropic magnetic field fluctuations, it is shown that most theories which are based on the quasi-linear and adiabatic approximations yield the same integral for the Fokker-Planck coefficient for the pitch-angle scattering of cosmic rays. For example, despite apparent differences, the theories due to Jokipii and to Klimas and Sandri yield the same integral. It is also shown, however, that this integral in most cases has been evaluated incorrectly in the past. For small pitch angles, the errors in previous evaluations are fortuitously of minor importance. For large pitch angles, however, these errors become more significant; and for pitch angles of 90 deg, the actual Fokker-Planck coefficient contains a delta function which has been overlooked in the past. The implications of these corrections on the possibility of relating cosmic-ray diffusion coefficients to observed properties of the interplanetary magnetic field are discussed.
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal; 190; June 1
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  • 64
    Publication Date: 2011-08-16
    Description: An empirical model for energetic solar proton fluxes is presented. With this model the effects of such protons on geocentric space missions, to be flown during the next solar active period (1977-1983), and with orbits involving partial magnetospheric shielding, may be estimated. A synoptic background review is given, followed by a detailed discussion of the model's use, errors, uncertainties, and limitations, including sample calculations which demonstrate the application of specific or general project missions. Finally, for circular trajectories, percentage exposure maps are presented, depicting fractional mission times spent outside particular L shells as functions of orbit altitude and inclination.
    Keywords: SPACE RADIATION
    Type: IEEE Transactions on Aerospace and Electronic Systems; AES-10; July 197
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  • 65
    Publication Date: 2011-08-16
    Description: This work determines criteria for stability of the lunar interior to thermal convection in the case of variable viscosity. The conditions necessary for solid convection to play an important role in the moon's revolution are determined by application of the calculated stability criteria to a variety of thermal history models. Most thermal history temperature profiles would be unstable to solid convection at the present time, if currently used estimates of the viscosity function are applicable. A possible explanation of lunar seismic data is that temperatures near the melting point of silicates exist at depths greater than 800 km. If this is the case, either the lunar interior is stable, or solid convection is occurring at a rate insufficient to cool the lunar interior substantially. If the former is true, the viscosity of lunar material is higher than that usually assumed.
    Keywords: SPACE SCIENCES
    Type: Journal of Geophysical Research; 79; July 10
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  • 66
    Publication Date: 2011-08-16
    Description: Heat transfer within the lunar surface layer depends on several thermophysical properties of the lunar regolith, including the thermal conductivity, the specific heat, the thermal diffusivity, and the thermal parameter. Results of property measurements on simulated lunar materials are presented where appropriate as well as measurements made on the actual samples themselves. The variation of temperature on the moon with depth is considered, taking into account various times of the lunar day. The daily variation in temperature drops to about 1 deg at a depth of only 0.172 meters. The steady temperature on the moon below this depth is 225 K.
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  • 67
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    Publication Date: 2011-08-16
    Description: The spectral identification of CH3CN and HCN provides the first support for the hypothesis first proposed by Wurm (1943), of chemically stable 'parent molecules' for the less stable radicals and ions seen in the coma and the tail. These two molecules were among the earliest discovered in dense interstellar clouds. Circumstantial evidence for the presence of water as the dominant volatile component in the nucleus has been growing for some time. However, a much more volatile species is required to explain the observed behavior of the comet. CO, formaldehyde, or methane would quickly evaporate as the comet approached the sun.
    Keywords: SPACE SCIENCES
    Type: Nature; 249; June 7
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  • 68
    Publication Date: 2011-08-16
    Keywords: SPACE SCIENCES
    Type: Solar Physics; 35; Apr. 197
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  • 69
    Publication Date: 2011-08-16
    Description: Approximate assessments are presented for the chemical state of the shock layer with respect to the hydrogen ionization reaction for representative entries into Saturn, Uranus, and Jupiter. It is shown that, except for a steep entry into the Saturn nominal atmosphere, the computation of all entry probe gascaps for the outer planets can probably be considered on either a frozen or chemical equilibrium basis.
    Keywords: SPACE SCIENCES
    Type: AIAA Journal; 12; June 197
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  • 70
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    Publication Date: 2011-08-16
    Description: The probability with which any given solar proton fluence level will be exceeded during a space mission is computed for mission to be flown during the active phase of the next solar cycle (1977-1983). This probability is a function of fluence level, proton energy threshold, and mission duration. Calculations are based on 1966-1972 data only. In estimating mission fluences, a distinction is made between ordinary and anomalously large events. Probable numbers of each type of event are estimated from Burrell's extension of Poisson statistics. Fluences of all anomalously large events are assumed to have a spectrum given by the August 1972 event, while fluences of the ordinary events are assumed to obey a log normal distribution.
    Keywords: SPACE RADIATION
    Type: Journal of Spacecraft and Rockets; 11; June 197
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  • 71
    Publication Date: 2011-08-16
    Description: Recent measurements using the Goddard-University of New Hampshire cosmic-ray telescope on the Pioneer 10 spacecraft have revealed an anomalous spectrum of nitrogen and oxygen nuclei relative to other nuclei such as He and C, in the energy range 3-30 MeV per nucleon. The intensity of nitrogen and oxygen nuclei is enhanced by a factor of up to 20 relative to their abundance in galactic or solar cosmic rays. It is argued that this is most likely a new extrasolar component of cosmic rays.
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal; 187; Feb. 1
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  • 72
    Publication Date: 2011-08-16
    Description: The MIT X-ray detectors aboard the OSO-7 spacecraft viewed Hercules X-1 from November 14 to 24, 1972. X-ray turn-on in the 35-day cycle was observed to occur between phases 0.67 and 0.70 (November 18.64-18.70). A significant decrease in the X-ray intensity occurred near mid-orbital phase, approximately 1.5 days after X-ray turn-on. Using the 1-6 keV data obtained during the 35-day off state, we conclude that if the optical light curve is due to heating of the large star by a blackbody source of soft X-rays, then the source must be large (radius greater than 5,000 km) and cool (temperature (kT) less than 90 eV). During one eclipse period (November 20.8-21.0) we find evidence for 1-6 keV X-ray emission.
    Keywords: SPACE SCIENCES
    Type: Astrophysical Journal; 188; Feb. 15
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  • 73
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    Publication Date: 2011-08-16
    Description: New measurements of the Ca II/Ca I ratios in interstellar clouds lead to the conclusion that not only Ca, but also Na, is underabundant in these regions. Recent calculations of element depletion by accretion of atoms onto dust grains probably cannot account for the observed abundance range. The extreme underabundance of Ca, and some part of the abundance range, probably reflect the composition of the grain cores.
    Keywords: SPACE SCIENCES
    Type: Astrophysical Journal; 187; Feb. 1
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  • 74
    Publication Date: 2011-08-16
    Keywords: SPACE SCIENCES
    Type: Astrophysical Journal; 189; Apr. 1
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  • 75
    Publication Date: 2011-08-16
    Description: We present models for temperature and ionization structure of low, uniform-density (approximately 0.3 per cu cm) interstellar gas in a galactic disk which is exposed to soft X rays from supernova outbursts occurring randomly in space and time. The structure was calculated by computing the time record of temperature and ionization at a given point by Monte Carlo simulation. The calculation yields probability distribution functions for ionized fraction, temperature, and their various observable moments. These time-dependent models predict a bimodal temperature distribution of the gas that agrees with various observations. Cold regions in the low-density gas may have the appearance of clouds in 21-cm absorption. The time-dependent model, in contrast to the steady-state model, predicts large fluctuations in ionization rate and the existence of cold (approximately 30 K), ionized (ionized fraction equal to about 0.1) regions.
    Keywords: SPACE SCIENCES
    Type: Astrophysical Journal; 189; Apr. 1
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  • 76
    Publication Date: 2011-08-16
    Keywords: SPACE SCIENCES
    Type: The Moon; 9; Mar
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  • 77
    Publication Date: 2011-08-16
    Description: V-shaped ridge components of the herringbone pattern associated with lunar secondary crater chains have been simulated by simultaneous and nearly simultaneous impact of two projectiles near one another. The impact velocities and angles of the projectiles were similar to those of the fragments that produced secondary craters found at various ranges from large lunar craters. Variables found to affect the included angles of the V-shaped ridges are: relative time of impact of the projectiles, impact angle, relative projectile mass, and azimuth angle of the crater chain relative to the projection of the flight line onto the target surface. The functional relationships between the forms of the ridges and many of these variables are similar to those observed for lunar V-shaped ridges. Comparison of the magnitudes of the ridge angles of both laboratory crater pairs and secondary crater chains of the crater Copernicus implies that material was ejected from Copernicus at angles in excess of 60 deg, measured from the normal, to form many of Copernicus' satellite craters.
    Keywords: SPACE SCIENCES
    Type: The Moon; 9; Mar
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  • 78
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    Publication Date: 2011-08-16
    Description: A search for lunar features that showed characteristics of terrestrial ring dikes was conducted, using the Lunar Orbiter series of photographs. Features exhibiting one or more of the following four criteria were included as lunar analogs to terrestrial ring dikes: (1) inner ridges approximately concentric with the crater wall, (2) inner rills approximately concentric with the crater wall, (3) outer ridges and/or rills approximately concentric with the crater wall, and (4) interior and exterior slopes of the crater wall approximately equal. Features exhibiting each of the four criteria were found, and some had combinations of two or more including rills merging into ridges - e.g., in Taruntius and Posidonius. Gambart is an example of equal inner and outer slopes, while Hesiodus A and Marth are two of the best examples of complete inner rings concentric with the outer rings. Ten per cent of the candidates were probable impact craters but had subsequent volcanic activity of a ring dike nature. The initial search showed a distribution of the possible lunar ring dikes that was nonrandom and strongly associated with the margins of the maria, further implying that they are volcanic features.
    Keywords: SPACE SCIENCES
    Type: The Moon; 9; Mar
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  • 79
    Publication Date: 2011-08-16
    Description: It is shown that the increase in apparent Doppler width as the limb is approached is a natural consequence of the fact that the solar atmosphere is not homogeneous. The work on the sodium D line cores which assumes the solar atmosphere to be homogeneous is reviewed. It appears that the cores of the sodium D lines have been distorted by fluctuations in the solar atmosphere in a systematic manner. It is concluded that the increase in apparent Doppler width observed in the sodium D line is a natural consequence of the temperature fluctuations in the solar atmosphere. The presence of a velocity field is not required to produce this effect.
    Keywords: SPACE SCIENCES
    Type: Royal Astronomical Society; vol. 166
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  • 80
    Publication Date: 2011-08-16
    Description: We have detected absorption features in the far-ultraviolet spectrum of zeta Tau (B3pe), one of which corresponds to a new transition involving quasi-H/-/, and the other to a transition involving quasi-H2/+/. The former transition produces a broad absorption feature on the red wing of L-alpha. It is the result of the absorption of a photon by a ground-state hydrogen atom and colliding electron, and it leads to the excitation of both electrons to the 2p2 3Pe state of H/-/.
    Keywords: SPACE SCIENCES
    Type: Astrophysical Journal; 187; Jan. 1
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  • 81
    Publication Date: 2011-08-16
    Description: Venera 8 measurements of solar illumination within the atmosphere of Venus are quantitatively analyzed by using a multilayer model atmosphere. The analysis shows that there are at least three different scattering layers in the atmosphere of Venus and the total cloud optical thickness is about 10 or greater. However, because of the nature of the observations, it is not possible to determine the vertical distribution of absorbed solar energy, which would reveal the drive for the atmospheric dynamics and the strength of the greenhouse effect. Future spacecraft observations should be designed to (1) measure both upward and downward solar fluxes, (2) include measurements of the highest cloud layers, and (3) employ narrow-band and broad-band sensors.-
    Keywords: SPACE SCIENCES
    Type: Science; 184; May 31
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  • 82
    Publication Date: 2011-08-16
    Description: The Vela pulsar PSR 0833-45, located in the Vela X nebula, has the second shortest period of any of the known radio pulsars. Soft X-ray observations are described which place an upper limit of 0.3% on the pulsed fraction of the Vela pulsar relative to the flux from the entire Vela X Nebula, in the 0.5- to 1.0-keV energy band. The present results are about a factor of 7 below the value of 2% measured by Harnden and Gorenstein (1973) for the pulsed fraction relative to the flux from the Vela X Nebula.
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal; 189; May 1
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  • 83
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    Publication Date: 2011-08-16
    Description: The long-period V/R emission variations in three Be stars, HD 20336, 25 Ori, and beta-one Mon have been studied according to the mathematical formulation of the eccentric rotating model presented in a previous paper. The predictions of the theory fit satisfactorily the general trend of observed data. Periods, eccentricities, and sizes of the emitting ring with respect to the stellar radius are thereby derived and found to be consistent with results of the previous investigation of 105 Tauri.
    Keywords: SPACE SCIENCES
    Type: Astrophysical Journal; 189; May 1
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  • 84
    Publication Date: 2011-08-16
    Description: The O-B5 stars, supergiants, young clusters, and associations within 1 kpc of the sun populate two flat systems inclined to each other by 19 to 22 deg. The historical background, statistical significance, composition, spatial arrangement of the contents, and interstellar extinction in the two belts are discussed. A more or less random distribution in space and in age characterizes the O-B5 stars of the 'galactic belt', which is aligned nearly along the Milky Way. The 'Gould belt' is inclined to the Milky Way (north in Sco-Oph and south in Orion), and exhibits a projected distribution of O-B5 stars in its mean plane that resembles a 'dragonfly', with five major features defining it. A crude 'diameter' of the system is 750 to 1000 pc, and the sun's position is eccentric, lying toward Ophiuchus. The nuclear age of the system, while not unique, may be characterized as 30 m.y. from the spectral type of the broad main-sequence turnup near B2-5. Most of the O-B2 stars and youngest stellar groups near the sun belong to the Gould belt, but both belts have approximately equal space densities of B3-B5 stars and similar average values of interstellar extinction.-
    Keywords: SPACE SCIENCES
    Type: Astronomical Journal; 79; Apr. 197
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  • 85
    Publication Date: 2011-08-16
    Keywords: SPACE SCIENCES
    Type: Astrophysical Journal; 189; Apr. 1
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  • 86
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    In:  Other Sources
    Publication Date: 2011-08-16
    Description: In an attempt to explain the observed unexpectedly high-energy gamma-radiation over a broad region of the galactic plane in the general direction of the galactic center, a model is proposed wherein the galactic cosmic rays are preferentially located in the high-matter-density regions of galactic arm segments, as a result of the weight of the matter in these arms tying the magnetic fields and hence the cosmic rays to these regions. The presently observed longitudinal distribution of galactic gamma-rays can be explained with the current estimate of the average galactic matter density, if the average ratio of arm to interarm matter is 5:1 for the major arm segments toward the galactic center from the sun, and if the cosmic-ray density normalized to its local value is assumed to be directly proportional to the matter density.
    Keywords: SPACE SCIENCES
    Type: Astrophysical Journal; 189; Apr. 15
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  • 87
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    In:  Other Sources
    Publication Date: 2011-08-16
    Description: The atmosphere of Mars is essentially a pure carbon dioxide atmosphere that contains a small and seasonably varying amount of water vapor. A number of minor constituents which arise from the interactions of solar radiation with water vapor and carbon dioxide include carbon monoxide, atomic oxygen, molecular oxygen, ozone, and atomic hydrogen. At the surface of Mars the atmospheric pressure is less than one hundredth of the pressure at the surface of the earth. Extensive cloud systems appear on Mars. The structure of the lower Martian atmosphere is discussed together with variations in the lower atmosphere and the characteristics of the upper atmosphere. Reactions of photochemistry are considered along with the atmospheric escape and interactions between the atmosphere and the polar caps.
    Keywords: SPACE SCIENCES
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  • 88
    Publication Date: 2011-08-16
    Description: The Brans-Dicke theory of gravitation is modified by assuming that the divergence of the energy-momentum tensor is proportional to the covariant derivative of the scalar curvature. No ad hoc additions to the usual Brans-Dicke field equations are required as in Rastall's modification of the Einstein theory or as in the steady-state theories, of which this is a natural possibility. Three parameters emerge from the theory - namely, the unnormalized gravitational constant, the usual Brans-Dicke parameter, and the proportionality constant. In the post-Newtonian approximation, these parameters can be fixed by experiment. However, there exists a certain choice of the parameters for which the theory reduces to an Einstein theory with constant scalar curvature.
    Keywords: SPACE SCIENCES
    Type: Physical Review D - Particles and Fields; vol. 9
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  • 89
    Publication Date: 2011-08-16
    Keywords: SPACE SCIENCES
    Type: The Moon; 9; Mar
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  • 90
    Publication Date: 2011-08-16
    Description: As the application of sequential filters has grown, the need has arisen to evaluate the sensitivity of these filters to mismodeling of the random process. A numerically reliable square-root algorithm is developed for calculating the covariances of estimates from a sequential filter which incorrectly models process noise. Mismodeling is restricted to the correlation time and standard deviation of a random process represented as a first-order Gauss-Markov sequence. Using a computer program which employs this algorithm, a sensitivity analysis was performed for several types of earth-based tracking data from an interplanetary spacecraft.
    Keywords: SPACE SCIENCES
    Type: Journal of Spacecraft and Rockets; 11; Apr. 197
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  • 91
    Publication Date: 2011-08-16
    Keywords: SPACE SCIENCES
    Type: Astrophysics and Space Science; 27; Apr. 197
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  • 92
    Publication Date: 2011-08-16
    Description: Results of laboratory simulation studies and comparative computer analyses of infrared spectral data regarding the presence, distribution, and form of condensed-phase water in the Martian surface. The data were obtained with the aid of the Mariner 6 and 7 spacecraft which were equipped with infrared spectrometers recording the infrared spectrum from 1.9 to 14.4 microns. From the analysis of these data evidence is obtained which signifies some sort of compositional and/or particle size variability of the extent and nature of hydration. Changes are noted which could be due to ice thinly covering a small fraction of the planetary surface in particularly cold spots, possibly on partially shaded slopes. At southerly latitudes, the fraction so covered seems to increase as the polar cap edge is approached. It is therefore concluded that there is strong evidence of ice formation on the planetary surface at the edge of the polar cap.
    Keywords: SPACE SCIENCES
    Type: Journal of Geophysical Research; 79; Apr. 10
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  • 93
    Publication Date: 2011-08-16
    Description: Mercury has a heavily cratered surface containing basins up to at least 1300 kilometers diameter flooded with mare-like material. Many features are closely similar to those on the moon, but significant structural differences exist. Major chemical differentiation before termination of accretion is implied.
    Keywords: SPACE SCIENCES
    Type: Science; 184; Apr. 26
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  • 94
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    In:  Other Sources
    Publication Date: 2011-08-16
    Description: Toulon is an olivine-bronzite chondrite found near Toulon, Illinois in 1962. It contains abundant, well preserved chondrules, as well as glasses that are not well devitrified. Most of the metal has been weathered out. Olivine and pyroxene are well equilibrated. It has been classified as an H5 chondrite.
    Keywords: SPACE SCIENCES
    Type: Meteoritics; 9; Mar. 30
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  • 95
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    In:  Other Sources
    Publication Date: 2011-08-16
    Description: Data are reported which provide the first large, homogeneous set of photoelectric and infrared photometry obtained for any comet. Assuming an albedo of 0.5 (a high albedo is assumed because of the large ratio of gas to dust in Kohoutek), the diameter of the nucleus of the comet is estimated to be 10 to 15 km. Based on a comparison with the infrared spectrum of Comet Bennett, it was calculated that the latter had about 16 times as much dust as Kohoutek. The data are used to obtain an evaluation of O'Dell's (1971) expression for the albedo of cometary dust grains in terms of the integrated infrared surface brightness and the surface brightness of scattered light in the continuum.
    Keywords: SPACE SCIENCES
    Type: Nature; 248; Apr. 26
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  • 96
    facet.materialart.
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    In:  Other Sources
    Publication Date: 2011-08-16
    Description: It is pointed out that the tenuous nature of the lunar atmosphere is maintained by rapid loss of gases released at the lunar surface. The loss of gases from the lunar atmosphere in the case of a greatly increased atmospheric density is investigated. It is found that in the case of such an increase in the density of the lunar atmosphere, a point can be reached where loss occurs so slowly that it is negligible over human time scales. In the event an artificial lunar atmosphere were to be created, gases can be obtained by heating or vaporization of the lunar soil. This could be done with the aid of nuclear devices.
    Keywords: SPACE SCIENCES
    Type: Nature; 248; Apr. 19
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  • 97
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    In:  Other Sources
    Publication Date: 2011-08-16
    Description: Oscillating velocity fields can be observed on H-alpha filtergrams as a shifting pattern of intensity fluctuations known as 'the galloping chromosphere'. The characteristics of this activity are those of horizontal running waves of typical period of about 300 sec and long wavelength (about 20,000 km) that can be interpreted as acoustic-gravity waves propagating in the acoustic domain. Periods are longer in dark, structured regions, and in fibrils, and the change is quantitatively consistent with the reduction of resonance frequency in a magnetic field of 1 to 10 gauss. These easily observed fluctuations thus offer a means of estimating magnetic-field strength at specific locations in the chromosphere. Phase velocities are high, ranging upward from typical values between 50 and 100 km per sec, and tending to be lower in active regions and toward the limb.
    Keywords: SPACE SCIENCES
    Type: Solar Physics; 35; Mar. 197
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  • 98
    Publication Date: 2011-08-16
    Description: Systematic variations of the properties of the helium constituent of the solar wind in the velocity streams are described. It is found that the helium abundance varies by about a factor of 2 as the stream is crossed. The velocity of the helium differs from that of the hydrogen by a few kilometers per second throughout much of the stream structure. This velocity difference is greatest immediately after the proton density peak passes, the helium velocity being typically 20 km/sec faster than the protons at that position in the stream. A sharp dip in the helium to proton temperature ratio is centered on the proton density peak. Although it appears reasonable that at least the velocity and temperature effects are due to the dynamic interactions of the two streams, it is not yet clear exactly what physical processes are directly involved in producing the effects described here.
    Keywords: SPACE RADIATION
    Type: Journal of Geophysical Research; 79; Mar. 1
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  • 99
    Publication Date: 2011-08-16
    Description: Analysis of the light curves and color-phase and polarization-phase relations of Geographos according to observations over an eight-month period in 1969. The light curves are relatively smooth with two distinct maxima and minima. The largest amplitude of 2.03 mag is the largest observed on asteroids to date. The average B-V is 0.87 and the average U-B is 0.50. A laboratory model that best reproduced Geographos' light curves was a cylinder having hemispherical ends with a length to width ratio of 2.7; on the basis of this model and a relation of Bowell and Zellner (1973), Geographos was calculated to be approximately 1.50 km wide and 4.0 km long.
    Keywords: SPACE SCIENCES
    Type: Astronomical Journal; 79; Feb. 197
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  • 100
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    In:  Other Sources
    Publication Date: 2011-08-16
    Description: Construction of a model explaining the means by which the interplanetary magnetic field could mix with the plasma of a comet tail. It is suggested that the magnetic fields in comet tails derive from the hydromagnetic conversion of kinetic energy into magnetic energy in the nuclear region of the comet. In particular, it is shown that, if the nuclear region consists of a supplementary distributed source for the coma gases, a turbulent flow with maximum velocities of the order of thermal velocity may be expected in this region, with the necessary ordering in the turbulent velocity field provided by the rotation of the nuclear region. It is concluded that a comet, when sufficiently close to the sun, may be able to generate an appreciable magnetic field and that the magnetic fields observed in the tail may then result from processes analogous to those producing the earth's magnetotail.
    Keywords: SPACE SCIENCES
    Type: Nature; 248; Mar. 1
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