Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “wind interaction”

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.

At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Solar wind interaction with lunar magnetic fields.

Two basic interaction modes have been identified: (1) deflection currents that close above the surface, typified by a subsurface dipole with its axis perpendicular to the surface, and (2) deflection currents that intersect the lunar surface, typified by a subsurface dipole with its axis parallel to the surface. The first results in a compression of the lunar field and, if it is strong enough, can stop the wind above the surface. The extent of compression depends on how much the wind is slowed before striking the surface. The second mode results in a small deflection of the wind. In both modes, charging up of the surface is important. The effects of discharging the surface charge through the photolayer and the lunar crust are found to be unimportant for typical lunar parameters.

Siscoe, G. L.↗
NASA NTRS1997

Study of the Solar Wind Interaction with Mars

The purpose of this study is to perform the following activities: (1) Implement the HALFSHEL code on the parallel machines at NASA Ames' NAS facility; (2) Perform test simulations of "bare" Mars object and compare results with data and previous simulations that only reached to the Martian terminator; (3) Place ion production chemistry into the parallel HALFSHEL code and test; (4) Simulate Mars at least 3 Rm into the tail region and compare the results to data; and (5) Examine the changes in the Martian magnetosphere by examining time dependent variation of the solar wind parameters. This paper details the progress made during the first four months of the contract in accordance with the contract requirements.

Source record↗
NASA NTRS1988

Comet-solar wind interaction through ion-proton beam instability

The acceleration of cometary ions in the distant cometary tail by an electromagnetic beam instability, which is caused by the relative drift velocity between the cometary ions and solar protons is studied. The linear phase of the instability is analyzed by numerical evaluation of the Vlasov dispersion relation. A particle simulation is used to study the nonlinear phase of the instability. Right-hand polarized cyclotron waves are made unstable by the presence of ion beams. The cometary tail ions are accelerated mainly during the reduced-growth phase of the instability. The cyclotron waves cause momentum transfer from solar wind protons to cometary tail ions. The acceleration of cometary ions through the electromagnetic beam instability is found to be 500-5000 cm/s-squared.

Price, Channon P.↗
NASA NTRS2003

NGC7009: Testing the Wind-Wind Interaction Formation of Planetary Nebulae

We have successfully obtained the XMM-Newton observations of NGC 7009. X-ray emission is detected from the interior of NGC 7009, and it is definite resolved, indicating a plasma emission. We have carried out both a spatial analysis and a spectral analysis. The spatial analysis is limited by the angular resolution of the telescope. It is possible to confirm the existence of diffuse emission from hot gas, but the detailed distribution of the hot gas and the amount of stellar emission cannot be determined. The spectral analysis shows that the plasma temperature is only about 2 x 10(exp 6) K. This is the coolest PN interior ever detected. A mixing of shocked fast stellar wind and the cool nebular material is needed. The results of our analysis have been reported in a paper published in the Astronomy and Astrophysics Letters, as given below.

Chu, You-Hua↗
NASA NTRS1972

Structure and orientations of solar-wind interaction fronts - Pioneer 6.

An analysis is given of five stream-stream interaction events observed in the Pioneer 6 plasma and field data. That the time profiles of all the parameters are consistent among the events and with previous descriptions given in the literature substantiates the notion of a common interaction type. The velocity variations in four of the events tend to lie in planes approximately parallel to the corotation spiral; thus it is implied that the events are reasonably stationary in time in the corotating frame. The data are interpreted in terms of a corotating interaction front, which is a ridge of high pressure parallel to a corotating spiral. The increased pressure is due to radial compression of the streams. The east-west (zonal) flow directions also occur in the front and are shown to be produced by the zonal pressure gradient of the pressure ridge.

Siscoe, G. L.↗
NASA NTRS1972

Type 1 Tails: Solar Wind Interactions

The ionization of the gas emitted by a comet is discussed along with the formation of a visible tail, and the bow shock front upstream toward the sun. Questions that a cometary probe can answer are listed.

Biermann, L.↗
NASA NTRS1980

Global observations of the composition and dynamics of the ionosphere of Venus - Implications for the solar wind interaction

The in-situ measurements of the global composition and Venus ionosphere dynamics recorded by the Bennett ion mass spectrometer on the Pioneer Venus orbiter during Dec. 1978-Aug. 1979 are presented. The observations of three plasma regimes show the bowshock-ionosheath region, the thermal ionosphere, and a superthermal flowing ion layer contacting the ionosphere at the ionopause and extending outward to different heights above the planet. An abundant ionosphere dominated by O(+) above 200 km and by O2(+) down to the typical periapsis altitudes of 160 km occur during quiet periods; less disturbed data shows strong day to night changes in the distributions of ions including O(+), O2(+), CO2(+), and N(+). The ionopause is located near the subpolar point at 250-400 km; under disturbed nighttime conditions it may have randomly spaced concentration gradients in the dusk region.

Taylor, H. A., Jr.↗
NASA NTRS1987

Comet-solar wind interaction as viewed from the International Cometary Explorer Mission (ICE) and from the earth

An overview of large-scale plasma phenomena is presented based on results of the ICE spacecraft probing of comet Giacobini-Zinner and on worldwide submissions to the Large-Scale Phenomena Discipline Specialist Team of the International Halley Watch. Results indicate that the magnetic field capture and draping model, originated by Alfven, is correct. Examples of tail 'turn on' and evolution are presented with emphasis on the observed Disconnection Events (DEs). The sector boundary model of DEs is consistent with the data and a dramatic example of synergism between in situ data from the VEGAs and ground-based imagery for the DE originating March 8.6, 1986 is presented.

Brandt, John C.↗
NASA NTRS1989

On the global nature of the solar wind interaction with Comet Halley

Data obtained by two instruments of the RPA-Copernic experiment aboard Giotto during its encounter with Comet Halley are used to determine the positions of several sharp boundaries delineating transitions from one flow state to another. Production rates of the neutrals are obtained, along with ion-neutral drag coefficients. It is suggested that the cometopause observed between the shock and the ionopause coincides with the expected position of a previously proposed collisionopause.

Mendis, D. A.↗
NASA NTRS1991

The solar wind interaction with Mars - Mariner 4, Mars 2, Mars 3, Mars 5, and Phobos 2 observations of bow shock position and shape

An aggregate Mars bow shock data set using Mariner 4, Mars 2, Mars 3, Mars 5, and Phobos 2 observations has been analyzed. The results support the earlier conclusion that the mean distance to the subsolar shock at Mars is nearly 1.5 planetary radii, from which gas dynamic models predict an obstacle altitude of 500 km. The Martian bow shock does not appear to vary significantly in shape or altitude with the phase of the solar cycle. The unusually distant dayside bow shock crossings reported by Mars 2 and 3 also appear in the Phobos 3 observations, suggesting that the dayside obstacle can on rare occasions reach altitudes over 1000 km. The Martian bow shock differs from that of Venus in that its mean altitude is greater, it lacks a strong solar cycle variation, and its location is far more variable, including the occurrence of strong bow shocks over the dayside hemisphere at distances at least as great as the orbit of Phobos 2, i.e., 2.8 Mars radii.

Slavin, J. A.↗
NASA NTRS1995

The solar wind interaction with Venus: A comparison of Galileo and Pioneer Venus observations

The rudimentary measurements of the instruments on Pioneer Venus over a 14-year span have provided a strong framework for the interpretation of the observations with a more sophisticated instrument package during the Galileo Venus flyby in February 1990. In some cases the Galileo results provided independent confirmation of earlier inferences. In other cases completely new data were obtained. Nevertheless, because of limitations of the instruments and the trajectory and thermal restraints some outstanding questions were not addressed. Much has been learned but there is still much more to do.

Russell, C. T.↗
NASA NTRS1996

Co-Investigator Participation in the Mars-94 Mission Studies of the Mars-Solar Wind Interaction: Topside Sounder and Magnetometer

The purpose of this investigation has been to provide United States co-investigator support toward the preparation of the Topside Ionospheric Sounder and Magnetometer experiments on the Russian Mars-96 (previously Mars-94) mission. The main role has been to assist in the preparation of software tools for the optimum design of the investigation and the evaluation of mission operational plans and orbits.

Luhmann, Janet G.↗
NASA NTRS1999

The Effects of Magnetic Anomalies Discovered at Mars on the Structure of the Martian Ionosphere and the Solar Wind Interaction as Follows from Radio Occultation Experiments

The electron density distribution in the ionosphere of nonmagnetic (or weakly magnetized) planet depends not only on the solar ultraviolet intensity, but also on the nature of the SW interaction with this planet. Two scenarios previously have been developed based on the observations of the bow shock crossings and on the electron density distribution within the ionosphere. According to one of them Mars has an intrinsic magnetosphere produced by a dipole magnetic field and the Martian ionosphere is protected from the SW flow except during "overpressure conditions, when the planetary magnetic field can not balance the SW dynamic pressure. In the second scenario the Martian intrinsic magnetic dipole field is so weak that Mars has mainly an induced magnetosphere and a Venus-like SW/ionosphere interaction. Today the possible existence of a sufficiently strong global magnetic field that participates in the SW/Mars interaction can no longer be supported. The results obtained by the Mars-Global-Surveyor (MGS) space-craft show the existence of highly variable, but also very localized magnetic fields of crustal origin at Mars as high as 400-1500 nT. The absence of the large-scale global magnetic field at Mars makes it similar to Venus, except for possible effects of the magnetic anomalies associated with the remnant crustal magnetization. However the previous results on the Martian ionosphere obtained mainly by the radio occultation methods show that there appears to be a permanent existence of a global horizontal magnetic field in the Martian ionosphere. Moreover the global induced magnetic field in the Venus ionosphere is not typical at the solar zenith angles explored by the radio occultation methods. Additional information is contained in the original extended abstract.

Ness, N. F.↗