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Data on the scattering of 1-MeV electrons in aluminum for the case of non-normal incidence, electron-bremsstrahlung cross-sections in thin targets, and the production of bremstrahlung by electron interaction in thick targets, are presented both in tabular and graphic form. These results may interest physicists and radiologists.
A common problem for experimental space physicists is the determination of the attitude matrix T which transforms vectors between representations in X and X' coordinate systems according to (vector V sub X) = (T sub XX')(vector V sub X'). A straightforward, simple, and efficient solution for the transformation matrix is a double-cross transformation. It is calculated from any two directions A and B, which are vectors normalized to unit length and are known in both X and X' coordinates. The B direction need be known only well enough to define the plane in which vectors A and B lie. The problem of the intersection of two cones as applicable to attitude solutions is also discussed.
Review of the respective contributions from the atmospheric physicist, trajectory analyst, and aerothermodynamist to the design problem underlying the selection of the space-shuttle booster mode to be developed, i.e., either expendable booster, recoverable booster, or flyback booster, and the configuration and composite configuration. The interrelationships between atmospheric variables, trajectory parameters, and aerodynamic heating loads are discussed.
The available techniques were examined in the field of remote sensing (including aerial photography, infrared detection, radar, etc.) and applications to a number of problems in the wide field of public health determined. The specific areas of public health examined included: air pollution, water pollution, communicable disease, and the combined problems of urban growth and the effect of disasters on human communities. The assessment of the possible applications of remote sensing to these problems was made primarily by examination of the available literature in each field, and by interviews with health authorities, physicists, biologists, and other interested workers. Three types of programs employing remote sensors were outlined in the air pollution field: (1) proving ability of sensors to monitor pollutants at three levels of interest - point source, ambient levels in cities, and global patterns; (2) detection of effects of pollutants on the environment at local and global levels; and (3) routine monitoring.
A symposium is reported on the implications of the possibility of extraterrestrial life for social, philosophical, and humanistic impacts. The viewpoints from astronomers, biologists, physicists, anthropologists, and theologians are given. Costs involved for finding this life are discussed along with the possible benefits to society. The direct implications from radio telescopes, the Pioneer 10 plaque, and discussions between the panelists are also reported.
The characteristics of propulsion systems required for carrying out flight missions within the solar system, as desired by planetary physicists and astronomers, are reviewed. It is shown that an encouraging answer to these requirements is available in the form of electrostatic or ion propulsion systems. The design and performance characteristics of an electrostatic thrustor employing an ion source, accelerating electrode, beam neutralizer, and power source are discussed, together with those of the Kaufmann engine (electrostatic thrustor employing bombardment type ionization). More demanding missions which will become feasible with the advent of nuclear-electric power sources (such as the incore thermionic reactor) may include close orbiters around all the planets, and asteroid and cometary missions.
The computer cost of a Poisson-Vlasov iteration procedure for the numerical solution of a steady-state collisionless plasma-sheath problem depends on: (1) the nature of the chosen iterative algorithm, (2) the position of the outer boundary of the grid, and (3) the nature of the boundary condition applied to simulate a condition at infinity (as in three-dimensional probe or satellite-wake problems). Two iterative algorithms, in conjunction with three types of boundary conditions, are analyzed theoretically and applied to the computation of current-voltage characteristics of a spherical electrostatic probe. The first algorithm was commonly used by physicists, and its computer costs depend primarily on the boundary conditions and are only slightly affected by the mesh interval. The second algorithm is not commonly used, and its costs depend primarily on the mesh interval and slightly on the boundary conditions.
This catalogue of solar cosmic ray events has been prepared for the use of solar physicists and other interested scientists. It contains some 185 solar particle events detected by the Goddard Space Flight Center Cosmic Ray Experiments on IMP's IV and V (Explorer 34 and 41) for the period May 1967 - December 1972. The data is presented in the form of hourly averages for three proton energy intervals - 0.9 - 1.6 MeV; 6 - 20 MeV and 20 - 80 MeV. In addition the time histories of .5 - 1.1 MeV electrons are shown on a separate scale. To assist in the identification of related solar events, the onset time of the electron event is indicated. The details of the instrumentation and detector techniques are described. Further descriptions of data reduction procedure and on the time-history plots are given.
The Skylab Ground-Based Astronomy Program (SGAP) was conducted to enhance the data base of solar physics obtained during the Apollo Telescope Mount (ATM) mission flown in conjunction with the Skylab orbital station. Leading solar physicists from various observatories obtained data from the ground at the same time that orbital data were being acquired by ATM. The acquisition of corollary solar data from the ground simultaneously with the ATM orbital observations helped to provide a broader basis for understanding solar physics by increasing spectral coverage and by the use of additional sophisticated instruments of various types. This report briefly describes the individual tasks and the associated instrumentation selected for this ground-based program and contains as appendices, the final reports from the Principal Investigators.
The general objectives of the Zero-Gravity Atmospheric Cloud Physics Laboratory Program are to improve the level of knowledge in atmospheric cloud research by placing at the disposal of the terrestrial-bound atmospheric cloud physicist a laboratory that can be operated in the environment of zero-gravity or near zero-gravity. This laboratory will allow studies to be performed without mechanical, aerodynamic, electrical, or other techniques to support the object under study. The inhouse analysis of the Skylab 3 and 4 experiments in dynamics of oscillations, rotations, collisions and coalescence of water droplets under low gravity-environment is presented.
A convenient guide to the expected characteristics of the Space Telescope Observatory for astronomers and physicists is presented. An attempt is made to provide enough detail so that a professional scientist, observer or theorist, can plan how the observatory may be used to further his observing programs or to test theoretical models.
The paper reviews efforts undertaken to explore the moon and the results obtained, noting that such efforts have involved a successful interdisciplinary approach to solving a number of scientific problems. Attention is given to the interactions of astronomers, cartographers, geologists, geochemists, geophysicists, physicists, mathematicians and engineers. Earth based remote sensing and unmanned spacecraft such as the Ranger and Surveyor programs are discussed. Emphasis is given to the manned Apollo missions and the results obtained. Finally, the information gathered by these missions is reviewed with regards to how it has increased understanding of the moon, and future exploration is considered.
Comprehensive information on the composition and dynamics of the varied planetary atmospheres is summarized. New observations resulted in new demands for supporting laboratory studies. Spectra observed from spacecraft used to interpret planetary atmospheric structure measurements, to aid in greenhouse and cloud physics calculations, and to plan future experiments are discussed. Current findings and new ideas of physicists, chemists, and planetry astronomers relating to the knowledge of the structure of things large and small, of planets and of molecules are summarized.
By its nature, the study of the origins of life is multidisciplinary, requiring contributions from astronomers, biologists, chemists, geologists, physicists, and many others. Partial answers are provided to many questions about organic chemical evolution and the origin of life. It is observed that the gaps in our knowledge concerning the steps from the nonliving to the living are numerous. Among these gaps are: (1) a solar system formation with its accumulation of raw materials; (2) the synthesis of the life forming monomers, such as the amino acids, nucleotides, and lipids; (3) the condensation of these monomers into useful polymers, such as proteins and nucleic acids; (4) the sequestering of these materials into droplets of proteinoid or membrane-like structures; and (5) the development of a chemical memory (the genetic code) to pass on to the progeny the information acquired.
The lunar magmasphere (or magma ocean) hypothesis was originally conceived to account for the enrichment of cumulus plagioclase (Al and Ca) in the main (highlands) portion of the crust. The great age of the highlands, and the complementary pattern of Eu anomalies between the highlands and the younger mare basalts, helped convince most specialists that the magmasphere hypothesis is correct. Doubts persist, however, particularly among physicists concerned about heat sources. It was shown in 1976 that a plot of Na/Ca vs. Mg/Fe for pristine highlands cumulates manifests a profound bimodality: One group, the Mg-rich rocks, plots along a normal igneous trend of inverse correlation between Na/Ca and Mg/Fe; the other group, the ferroan anorthosites (FAN), features low Na/Ca and low Mg/Fe. Only the FAN group can be plausibly linked to plag. flotation over the magmasphere.
In the interest of exploring the cosmic ray spectrum at energies greater than 10 to the 18th power eV, where flux rates at the Earth's surface drop below 100 yr(-1) km(-2) sr(-1), cosmic ray physicists have been forced to construct ever larger detectors in order to collect useful amounts of data in reasonable lengths of time. At present, the ultimate example of this trend is the Fly's Eye system in Utah, which uses the atmosphere around an array of skyward-looking photomultiplier tubes. The air acts as a scintillator to give detecting areas as large as 5000 square kilometers sr (for highest energy events). This experiment has revealed structure (and a possible cutoff) in the ultra-high energy region above 10 o the 19th power eV. The success of the Fly's Eye experiment provides impetus for continuing the development of larger detectors to make accessible even higher energies. However, due to the rapidly falling flux, a tenfold increase in observable energy would call for a hundredfold increase in the detecting area. But, the cost of expanding the Fly's Eye detecting area will approximately scale linearly with area. It is for these reasons that the authors have proposed a new approach to using the atmosphere as a scintillator; one which will require fewer photomultipliers, less hardware (thus being less extensive), yet will provide position and shower size information.
An overview and synthesis is given of recent developments that have occurred in the areas of Forbush decreases, geomagnetic and atmospheric effects, and cosmogenic nuclides. Experimental evidence has been found for substantial differences in the effects of the various types of interplanetary perturbations on cosmic rays, and for a dependence of these effects on the three-dimensional configuration of the interplanetary medium. In order to fully understand and to be able to simulate the solar cosmic ray particle access to the polar regions of the earth we need accurate models of the magnetospheric magnetic field. These models must include all major magnetospheric current systems (in particular the field aligned currents), and they should represent magnetically quiet time periods as well as different levels of geomagnetic activity. In the evolution of magnetospheric magnetic field models, cosmic ray and magnetospheric physicists should work closely together since cosmic ray measurements are a powerful additional tool in the study of the perturbed magnetosphere. In the field of cosmogenic nuclides, finally, exciting new results and developments follow in rapid succession. Thanks to new techniques and new isotopes the analysis of cosmic ray history has entered into a new dimension.
New methods for the measurement of OH radicals were assessed as were currently available and possible future methods for the other H sub x O sub y species, HO2 and H2O2. The workshop participants were invited from different groups: modelers of atmospheric photochemistry, experimentalists measuring H sub x O y species with laser and nonlaser methods, and chemists and physicists familiar with such experiments but not involved in atmospheric monitoring. There were three major conclusions from the workshop concerning the OH radical. First, it was felt that local measurements made by laser techniques would be ready within 2 or 3 years to furnish reliable measurements at the level of 1,000,000 cu. cm. Second, measurements at this level of sensitivity and with attainable levels of precision could indeed be used to make useful and interesting tests of the fast photochemistry of the troposphere. It is important, however, that the measurements be carefully designed, with respect to spatial and temporal averaging, if there is to be a meaningful comparison between results from two experimental methods or a measurement and a model. Third, nonlocal measurements using released reactants and tracers would also be very useful. These could be made on a regional or global basis, although they still require experimental design including choice of compounds.