A temperature profile of the upper Martian atmosphere from a kinetic viewpoint
Temperature profile of upper Martian atmospheric models in terms of kinetic theory applied to ideal gases in gravitational force fields
Johnson, J. W.↗
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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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Lunar orbital science
Lunar orbital science, discussing U.S. and Soviet missions, NASA plans and results concerning remote sensing, force field and particle studies
Allenby, R. J.↗
Relative motion of two particles in elliptic orbits
Two particles relative motion in elliptical orbits in inverse square central force field
Lancaster, E. R.↗
A different look at mascons
Comparison of tracking rate residuals attributed to mascons with orbital calculation effects using error containing earth force fields
Woolston, D. S.↗
Research capabilities
Manned space station research capabilities in earth orbital environment for agravic force field, hard vacuum, cosmic radiation and spatial disposition
Keller, G. A.↗
Approximations in the theory of solar-cycle modulation
Force field model for galactic cosmic rays modulation by solar cycles, noting agreement with Fokker-Planck equation analytic and numerical solutions
Axford, W. I.↗
Activity in galaxies and quasars
Activity in galaxies and quasars is interpreted in terms of plasma processes occurring in the magnetosphere of a magnetoid model. The magnetoid is comprised of a core and an annulus rotating about a common axis with different angular velocities. It is conjectured that the transition from a closed force field configuration to an open one will be effected by an MHD eruptive instability, and that such eruptions lead to high velocity clouds of cool gas, identified with clouds producing absorption lines in quasars. The ejection of radio clouds from galaxies and quasars is attributed to galactic flares. Current sheets contain mildly relativistic electrons moving in directions partially transverse to the magnetic field. Synchrotron radiation from these electrons is held responsible for the nonthermal radiation from quasars and certain galaxies. It is proposed that minor instabilities of the current sheets are responsible for fluctuations in the nonthermal luminosity and for small scale radio bursts sometimes observed.
Sturrock, P. A.↗
Solar modulation of galactic cosmic rays. 3: Implications of the Compton-Getting coefficient
Spectra of modulated galactic cosmic rays are expressed in terms of the Compton-Getting coefficient C. This parameter can reveal the energy range over which the force field approximation is valid, and the range where convection effects dominate those of diffusion. A value of C near zero over an extended low energy range implies that the radial gradient at low energies can not be large. This small gradient may imply that the diffusion coefficient increases beyond 1 AU less rapidly than proportionally to heliocentric radial distance, and/or there is essentially no scattering for a sizeable distance from the Sun to earth. The behavior of C with rigidity (or energy) is discussed in terms of the omnidirectional distribution function f sub zero. Contours of constant f sub zero in the heliocentric distance vs rigidity plane are useful for illustrating the mean rigidity loss experienced by cosmic rays in the interplanetary medium.
Fisk, L. A.↗
Charged-particle transport in turbulent astrophysical plasmas
The effect of electromagnetic fluctuations, or plasma turbulence, on the motion of the individual particles in a plasma is investigated. Two alternative methods are used to find a general equation governing the time-evolution of a distribution of charged particles subject to both an external force field and the random fields of the fluctuations. It is found that, for the high-temperature, low-density plasmas frequently encountered in the study of astrophysics, the presence of even a small amount of turbulence can have a very important effect on the behavior of the plasma. Two problems in which turbulence plays an important role are treated.
Newman, C. E., Jr.↗
Growth of a single crystal ribbon in space
Three critical technological areas associated with adapting the method of pulling signal crystal silicon ribbon to a space environment were investigated. Basic parameters such as the magnitude of the forces required and the coupling between thermal and force are discussed. The design of a ribbon puller is described, and the problems encountered are also discussed. The force fields in the vicinity of a coil were characterized and results of attempts to pull ribbon are described. The results of the one experiment to grow a conventional float zone crystal in an external static magnetic field are presented.
Padovani, F. A.↗
Mini-arc orbit determination for the Geos C altimetry experiment.
The problem is, given simultaneous observations of an altimeter-bearing geodetic satellite, from three or more high-precision radar stations, to determine its orbit to submeter accuracy in the presence of perturbations arising from strong, localized gravitational anomalies. A new solution to this problem involves the use of an f and g series specialized to the determination of radial distance (pertinent to the satellite altimeter experiment) to process data over a very short arc (e.g., 6 sec to 10 min). Such a short arc is termed a 'mini-arc.' In this approach, the data batches are connected by dynamics, rather than by the usual curve fit to a power series in time. A nonunity value of the mass factor is introduced to serve as an 'alias' for the perturbations that affect the satellite's path during the mini arc. The essence of the mini-arc approach is to include the influence of the far, or relatively lower-order, force field analytically and to solve for the remaining fine structure with accuracies that can approach a few centimeters.
Baker, R. M. L., Jr.↗
Status report on Skylab project.
The major objectives of the Skylab project are to examine the medical aspects of what happens to man in long duration space flight, to make long-duration studies of the active and the quiet sun, and to gather data in the study of the ocean and the land masses of the earth. Corollary experiments use either the fact that they are to be performed in a complete vacuum, or the fact that the stars and the ultraviolet can be much more extensively studied. Some experiments in metal processing will make use of the zero force field.
Conrad, C., Jr.↗
Further analysis of field effects on liquids and solidification
Numerical calculations of the magnitude of external field effects on liquids are presented to describe how external fields can influence the substructure of the field. Quantitative estimates of magnetic and gravitational effects are reported on melts of metals and semiconductors. The results are condensed in tables which contain the input data for calculation of the field effects on diffusion coefficient, solidification rate and for calculation of field forces on individual molecules in the melt.
Seiler, R. F.↗
Liapunov stability analysis of hybrid dynamical systems in the neighborhood of nontrivial equilibrium
This paper is concerned with the stability of a hybrid dynamical system in the neighborhood of a nontrivial equilibrium, where the system consists of one rigid part and n elastic members. The body moves in a central-force field with its mass center describing a circular orbit. The nontrivial equilibrium is defined by steady rotation of the system at an angular velocity equal to the orbital velocity, with the elastic members being in deformed state. A Liapunov stability analysis is performed by assuming small perturbations about the nontrivial equilibrium, where the latter is generally defined by nonlinear differential equations. The theory is applied to a gravity-gradient stabilized satellite with flexible appendages.
Meirovitch, L.↗
Particle distribution functions in modulation theory
Development of a simple formulation of the cosmic ray modulation problem which involves the use of the omnidirectional part of the distribution function in phase space, and the magnitude of the momentum or the rigidity. It is shown that, by employing the proposed formulation, the Compton-Getting factor is greatly simplified, and the well-known force-field equation is reduced to a one-dimensional Vlasov equation. In addition, another Vlasov equation can be written for the very low energy galactic particles which are convected by the solar wind.
Forman, M. A.↗
Analytic approximations in the study of the solar modulation of electrons
Numerical solutions to the transport equation of galactic cosmic rays in the interplanetary medium have been used to investigate the applicability of commonly used approximate analytic solutions for electrons (10 MeV to 10 GeV). We find that for a given cosmic-ray diffusion coefficient the force-field approximation is in reasonable agreement with the numerical solution at energies above 200 MeV, but deviates significantly at lower energies, depending on the shape of the interstellar electron spectrum. The diffusion-convection approximation agrees generally with the numerical solution within a factor of 2 over the entire energy range.
Cummings, A. C.↗
Magnetic field and electric current structure in the chromosphere
The three-dimensional vector magnetic field structure in the chromosphere above an active region is deduced by using high-resolution H-alpha filtergrams together with a simultaneous digital magnetogram. An analog model of the field is made with 400 metal wires representing field lines that outline the H-alpha structure. The height extent of the field is determined from vertical field-gradient observations around sunspots, from observed fibril heights, and from an assumption that the sources of the field are largely local. The computed electric currents (typically 10 mA/sq m) are found to flow in patterns not similar to observed features and not parallel to magnetic fields. Force structures correspond to observed solar features; the dynamics to be expected include: downward motion in bipolar areas in the lower chromosphere, an outflow of the outer chromosphere into the corona with radially outward flow above bipolar plage regions, and motion of arch filament systems.
Dravins, D.↗
Studies of earth simulation experiments
The low gravity environment of earth orbit offers the potential for performing experiments involving baroclinic Geophysical Fluid Dynamics (GFD) on spherical surfaces. These experiments in turn have the potential for providing deeper understanding of large scale planetary and solar circulations. However, to perform these experiments, one requires an experimental technique whereby a radially directed body force can be generated to simulate a radial gravitational force field. One viable technique is the use of dielectric fluids with temperature dependent dielectric permittivity in a radially directed electric field. Application of the Boussinesq approximation to the equations of motion for this system and restrictions on the size of certain electrodynamic terms in the energy equations yields a set of equations which are analogous to the equations of motions of geophysical systems like the earth's atmosphere on term by term basis. The theoretical design of GFD experiments for performance in earth orbit are described along with results of preliminary tests of a prototype.
Hart, J. E.↗