Cosmic rays and dynamics of the solar wind, 2
Integro-differential equation describing cosmic ray interaction with solar wind
Dorman, I. V.↗
SEARCH · Search NASA
Results for “Solar Dynamic”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
The effect of galactic cosmic rays upon the dynamics of the solar wind
Galactic cosmic rays scattering by solar wind magnetic field fluctuations, considering energy and momentum transfer
Lenchek, A. M.↗
Dynamics of the solar wind and its interaction with bodies in the solar system
A discussion of the solar wind and its interaction with bodies of the solar system is presented. An overall unified account of the role of shock waves in the heating of the solar corona, the transmission of solar disturbances to the solar system, the flow fields of planets and natural satellites, and biological effects are provided. An analysis of magnetometer data from Explorer 33 and Vela 3A satellites to identify characteristics of solar wind shock waves is included.
Spreiter, J. R.↗
Structural evaluations and dynamic testing of solar electric propulsion components.
Results of an experimental and analytical study of selected Solar Electric Propulsion (SEP) thrust subsystem components are presented. A mass and center-of-mass mockup of an experimental power conditioning (PC) panel was used for the PC structure evaluation. Test environment was based on that specified for prooftesting the Viking spacecraft electronics. Modal frequencies were surveyed over the range of 0-2000 Hz using both conventional test equipment and the holographic interferometry technique. Results of the forced vibration tests point to the need for some additional stiffening to make the structure qualifiable.
Womack, J. R.↗
Dynamics of the solar wind and its interaction with bodies in the solar system
The results of the research related to solar winds are presented. Also included is a summary of papers and publications completed.
Source record↗
Hydrostatic and dynamic models of solar coronal holes
A description is presented of a sequence of one-dimensional fluid flow models of the transition zone and the inner corona. A hydrostatic model atmosphere in reasonable agreement with observations of closed, large-scale coronal structures found in the quiet sun is considered and various physical effects are introduced, one at a time, observing the response of the model. As a result of the investigations, a model is developed of the plasma flow in a coronal hole. It is shown that the data severely circumscribe the allowable range of possible models.
Rosner, R.↗
Dynamics of the solar transition zone
Time-resolved profiles of the 1548-A C IV line arising from the solar transition region are analyzed in order to determine whether the 300-sec oscillations characteristic of the photosphere and chromosphere penetrate into the transition zone and to measure the rms amplitude of transition-zone disturbances as well as their dependence on solar activity. The rms velocity amplitude is used to set limits on the mechanical energy flux available for solar heating. A power-spectrum analysis indicates that acoustic waves appear to have been detected in the transition zone, that at least one case of a strong 200- to 300-sec oscillation was observed, but that strong periodicities are not found on the average in either the intensity or the velocity field. It is suggested that the rms velocity that may be attributed to directly observable wave motion is between 3 and 7 km/s, depending on whether the individual emission elements seen in rocket spectra are coherent or independent in phase.
Bruner, E. C., Jr.↗
Dynamics of the solar photosphere
Current knowledge of photospheric velocity fields is summarized. A model of the solar atmosphere is described along with the methods used in solar velocity field observations. The inferences drawn from integrated Sun observations, the velocity fields of the quiet Sun, sunspots, and other magnetic structures are discussed.
Beckers, J. M.↗
What Would a Dynamo Theorist like to Know About the Dynamics of the Solar Convection Zone?
Observations about the current status of solar dynamo theory are given. The induction equation for magnetic field is solved using assumed velocities and parametric representations of the inductive or diffusive effects of velocities. The equations of motion governing these flow are not solved in parallel. Results from global compressible convection models are discussed. Differential rotation and convection are also investigated.
Gilman, P. A.↗
Urey Prize Lecture - Chaotic dynamics in the solar system
Attention is given to solar system cases in which chaotic solutions of Newton's equations are important, as in chaotic rotation and orbital evolution. Hyperion is noted to be tumbling chaotically; chaotic orbital evolution is suggested to be of fundamental importance to an accounting for the Kirkwood gaps in asteroid distribution and for the phase space boundary of the chaotic zone at the 3/1 mean-motion commensurability with Jupiter. In addition, chaotic trajectories in the 2/1 chaotic zone reach very high eccentricities by a route that carries them to high inclinations temporarily.
Wisdom, Jack↗
Analysis of the flight dynamics of the Solar Maximum Mission (SMM) off-sun scientific pointing
Algorithms are presented which were created and implemented by the Goddard Space Flight Center's (GSFC's) Solar Maximum Mission (SMM) attitude operations team to support large-angle spacecraft pointing at scientific objectives. The mission objective of the post-repair SMM satellite was to study solar phenomena. However, because the scientific instruments, such as the Coronagraph/Polarimeter (CP) and the Hard X ray Burst Spectrometer (HXRBS), were able to view objects other than the Sun, attitude operations support for attitude pointing at large angles from the nominal solar-pointing attitudes was required. Subsequently, attitude support for SMM was provided for scientific objectives such as Comet Halley, Supernova 1987A, Cygnus X-1, and the Crab Nebula. In addition, the analysis was extended to include the reverse problem, computing the right ascension and declination of a body given the off-Sun angles. This analysis led to the computation of the orbits of seven new solar comets seen in the field-of-view (FOV) of the CP. The activities necessary to meet these large-angle attitude-pointing sequences, such as slew sequence planning, viewing-period prediction, and tracking-bias computation are described. Analysis is presented for the computation of maneuvers and pointing parameters relative to the SMM-unique, Sun-centered reference frame. Finally, science data and independent attitude solutions are used to evaluate the large-angle pointing performance.
Pitone, D. S.↗
Analysis of the flight dynamics of the Solar Maximum Mission (SMM) off-sun scientific pointing
Algorithms are presented which were created and implemented by the Goddard Space Flight Center's (GSFC's) Solar Maximum Mission (SMM) attitude operations team to support large-angle spacecraft pointing at scientific objectives. The mission objective of the post-repair SMM satellite was to study solar phenomena. However, because the scientific instruments, such as the Coronagraph/Polarimeter (CP) and the Hard X-ray Burst Spectrometer (HXRBS), were able to view objects other than the Sun, attitude operations support for attitude pointing at large angles from the nominal solar-pointing attitudes was required. Subsequently, attitude support for SMM was provided for scientific objectives such as Comet Halley, Supernova 1987A, Cygnus X-1, and the Crab Nebula. In addition, the analysis was extended to include the reverse problem, computing the right ascension and declination of a body given the off-Sun angles. This analysis led to the computation of the orbits of seven new solar comets seen in the field-of-view (FOV) of the CP. The activities necessary to meet these large-angle attitude-pointing sequences, such as slew sequence planning, viewing-period prediction, and tracking-bias computation are described. Analysis is presented for the computation of maneuvers and pointing parameters relative to the SMM-unique, Sun-centered reference frame. Finally, science data and independent attitude solutions are used to evaluate the larg-angle pointing performance.
Pitone, D. S.↗
Structural dynamic interaction with solar tracking control for evolutionary Space Station concepts
The sun tracking control system design of the Solar Alpha Rotary Joint (SARJ) and the interaction of the control system with the flexible structure of Space Station Freedom (SSF) evolutionary concepts are addressed. The significant components of the space station pertaining to the SARJ control are described and the tracking control system design is presented. Finite element models representing two evolutionary concepts, enhanced operations capability (EOC) and extended operations capability (XOC), are employed to evaluate the influence of low frequency flexible structure on the control system design and performance. The design variables of the control system are synthesized using a constrained optimization technique to meet design requirements, to provide a given level of control system stability margin, and to achieve the most responsive tracking performance. The resulting SARJ control system design and performance of the EOC and XOC configurations are presented and compared to those of the SSF configuration. Performance limitations caused by the low frequency of the dominant flexible mode are discussed.
Lim, Tae W.↗
Structural dynamic interaction with solar tracking control for evolutionary Space Station concepts
The paper addresses the sun tracking control system design of the Solar Alpha Rotary Joint (SARJ) and the interaction of the control system with the flexible structure of Space Station Freedom (SSF) evolutionary concepts. The significant components of the Space Station pertaining to the SARJ control are described, and the tracking control system design is presented. Finite element models representing two evolutionary concepts, Enhanced Operations Capability (EOC) and Extended Operations Capability (XOC), are employed to evaluate the influence of low frequency flexible structure on the control system design and performance. The design variables of the control system are synthesized using a constrained optimization technique to meet design requirements, to provide a given level of control system stability margin, and to achieve the most responsive tracking performance. The resulting SARJ control system design and performance of the EOC and XOC configurations are presented and compared to those of the SSF configuration.
Lim, Tae W.↗
Dynamics of the solar chromosphere. I - Long-period network oscillations
We analyze differences in solar oscillations between the chromospheric network and internetwork regions from a 1 hr sequence of spectrograms of a quiet region near disk center. The spectrograms contain Ca II H, Ca I 422.7 nm, and various Fe I blends in the Ca II H wing. They permit vertical tracing of oscillations throughout the photosphere and into the low chromosphere. We find that the rms amplitude of Ca II H line center Doppler fluctuations is about 1.5 km/s for both network and internetwork, but that the character of the oscillations differs markedly in these two regions. Within internetwork areas the chromospheric velocity power spectrum is dominated by oscillations with frequencies at and above the acoustic cutoff frequency. They are well correlated with the oscillations in the underlying photosphere, but they are much reduced in the network. In contrast, the network Ca II H line center velocity and intensity power spectra are dominated by low-frequency oscillations with periods of 5-20 min. Their signature is much clearer in our Ca II H line center measurements than in previously used diagnostics which are contaminated by signals from deeper layers. We find that these long-period oscillations are not correlated with underlying photospheric disturbances, and we discuss their nature.
Lites, B. W.↗
Solar convection zone dynamics and rotation
Helioseismology reveals that there appears to be a discrepancy between the differential rotation profile with the radius and latitude deduced from the inversion of the observed frequency splitting of p-modes and the rotation profile anticipated from various global simulations of convection in rotating shells. The problem may be caused by deductions in numerical simulations of convection which was considered near laminar flows. A high performance computing offers paths for studying the properties of such astrophysical turbulence. A range of approaches to study the basic dynamics of convection is reviewed, along with its ability to redistribute angular momentum in rotating systems. The results of recent three-dimensional simulations of turbulent compressible convection constrained by the effects of rotation are described for the cases in spherical shells and local area f-planes. The turbulence possesses intense vortex tubes with intricate interactions and instabilities. The theoretical studies reveal that the transition to turbulent states has contributed to significant changes in flow symmetries and transports, and that such a turbulent convection can drive substantial mean flows, which are distinctly different from those in which the convection is dominantly laminar.
Toomre, Juri↗
Seismic Study of the Subsurface Structure and Dynamics of the Solar Interior from High Spatial Resolution Observations
We have carried out the data reduction and analysis of Mt. Wilson 60' solar tower high spatial resolution observations. The reduction of the 100-day-long summer of 1990 observation campaign in terms of rotational splittings was completed leading to an excess of 600,000 splittings. The analysis of these splittings lead to a new inference of the solar internal rotation rate as a function of depth and latitude.
Korzennik, Sylvain G.↗
The Structure and Dynamics of the Solar Corona
This report covers technical progress during the first year of the NASA Space Physics Theory contract between NASA and Science Applications International Corporation. Under this contract SAIC, the University of California, Irvine (UCI), and the Jet Propulsion Laboratory (JPL), have conducted research into theoretical modeling of active regions, the solar corona, and the inner heliosphere, using the MHD model. During the period covered by this report we have published 26 articles in the scientific literature. These publications are listed in Section 4 of this report. In the Appendix we have attached reprints of selected articles.
Mikic, Zoran↗