Solar and Space Physics Space Science in the Twenty-First Century -- Imperatives for the Decades 1995 to 2015 (1988) / Chapter Skim
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Appendix A: Workshop on Imaging of the Earth's Mangetosphere
Appendix A: Workshop on Imaging of the Earth's Mangetosphere
Pages 57-78
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From page 57... ...
This workshop was convened by the task group at the NAS Woods Hole study center during the task group meeting of July 1985. Appendix A represents the complete report.
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From page 59... ...
Appendix A Workshop on Imaging of the Earth's Magnetosphere WORKSHOP PARTICIPANTS Lyle Broadfoot, University of Arizona Andrew Cheng, Johns Hopkins University/Applied Physics Laboratory Paul Feldman, Johns Hopkins University David Gorney, Aerospace Corporation Warren Moos, Johns Hopkins University Edward Roelof, Johns Hopkins University Donald Shemansky, University of Arizona Donald Williams, Johns Hopkins University/Applied Physics I.aboratory so
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From page 60... ...
60 CONTENTS A.1 ~troducUon, 61 AN Imaging of the Aurora Oval: Present Status and Future Needs, 64 A.3 Prospects far Extreme Ultraviolet Dogleg ~ Plums in the ~agnetospbere, 66 A.4 Prospects far Neutral Particle Imaging of Planetary ~agnetospberes, 72 A.S Conclusions and Recommendatlons, 77 l
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From page 61... ...
Because of their enormous sizes and because there are largescale variations in both space and time, planetary magnetospheres pose major challenges to scientists attempting to understand global behavior an understanding that ~ necessary in a program aimed at developing quantitative predictive models of these systems. Since single-po~nt observations from an molated satellite within the magnetosphere are obviously inadequate for this task, the initial response to the challenge of studying global behavior has been to conduct sunultaneous multmatellite observations within the magnetospheric system.
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From page 62... ...
program represents a major new thrust in our attempt to understand global magnetospheric dynamics. This program, specifically designed for global studies, will place appropriately instrumented satellites in key magnetospheric locations, and simultaneous auroral imaging will be utilized to obtain data on the magnetospheric energy deposition into the atmosphere.
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From page 63... ...
hL - ~ FIGURE A.1 Ultraviolet auroral images from Dynamics Explorer.
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From page 64... ...
plasma of the plasmsphere, magnetopause, bow shock, and storm-time plasma sheet. The use of energetic neutral (generated by charge exchange)
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From page 65... ...
The ISTP polar spacecraft will carry multispectral auroral imagers that will cover visible, ultraviolet, and x-ray wavelengths, and the payload will also include advanced instrumentation for measurements of local plasma physics phenomena.
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From page 66... ...
Required integration time A = lOO cm2. A.3 PROSPECTS FOR EXTREME ULTRAVIOLET IMAGING OF PLASMA IN THE MAGNETOSPHERE Plasma temperatures above about 40,000°K generally produce ions with resonance transitions into the EUV region of the spectrum.
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From page 67... ...
BANDS . ., ~~A ~ ,' PLANETARY H Low >a lV- rev ..rA\J~ ~,f,f~ (A -C~05 FIGURE A.3 Spatially and spectrally resolved image of Jupiter and the lo plasma torus obtained by the Voyager EUV spectrometer.
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From page 68... ...
Knowledge of the solar differential flux distribution and the spectral shape of the scattered radiation allows diagnostics of bulk motion of the plasma as well as plasma temperatures. The image of the terrestrial plasmasphere obtained by a photometer coupled to an array detector is illustrated in Figure A.4; these profiles have been calculated using a specific mode!
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From page 69... ...
These global observations of the magnetosphere must clearly be linked to direct parallel measurements of solar activity, and followed through a time scale of one or more major solar cycles.
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From page 70... ...
The time scale is also about right for the study of typical solar-magnetospheric interactions. The changing aspect of the lunar orbit is important for viewing interface regions such as the
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From page 71... ...
The solar wind can also be measured continuously from the L1 station, allowing detailed study of the effect of solar wind variability on the magnetospheric system. From here one could also study changes in the solar flux spectrum and intensity; this information is of importance for atmospheric analysis, and it is also needed for the complete interpretation of the resonance emissions from the magnetospheric plasma.
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From page 72... ...
These measurements directly point the way toward an innovative class of instruments devoted to global imaging of magnetospheric neutral particle emissions. Energetic neutrals are created within the magnetosphere by charge exchange reactions between fast magnetospheric ions and ambient neutral atoms or molecules (see Figure Am.
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From page 73... ...
Analysis of ISE~1 and IMP 7,8 data has revealed energetic neutral particle emissions from charge exchanges between ring current ions and hydrogen atoms of Earth's geocorona. Figure A.7 is an example (constructed from an eigh~pixe!
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From page 74... ...
of Figure A.S then shows the line-of-sight ion flux column density for the main phase ring current distribution deduced from the measured neutral atom intensity profile in the bottom panel. Energetic neutral particles also contain specific information on the composition of the magnetospheric energetic ions.
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From page 75... ...
75 _CR~ _ ~~ 1 ~ ~ o US ·— ._ ~ I so ·m o ·_ ~ o ._ Co' ~ ., ._ o A, ~ ._ o 3 o Ce Cal b,O Al ~ ._ ~ L
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From page 76... ...
~ Near-Earth 104 lolo 0.01 0.1/sec,-10° Plasma Sheet Quiet Time 2 x 104 5 x 1011 1a O.s/~,a -2O Radiation Belh Storm Time 3x 105 5 x 1011 1Sa 7.5/s,a -2O Ring Current aEnergetic neutral intensities and count rates up to an order of magnitude greater are predicted if O dominates rather than protons. The neutral particle intensity from charge exchanges in the Earths magnetosphere is estimated from the integral along the line of sight of the product of the ion intensity, the charge exchange cross section, and the neutral density.
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From page 77... ...
At Jupiter, energetic neutral imaging fulfills a unique role. It is the only known way of continuously sampling the very intense charged particle population in the innermost region of the Jovian radiation belts, where particle detectors are saturated (and heavily damaged)
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From page 78... ...
are best ~imaged" by searching for energetic neutral atoms produced by charge exchange. The very low resolution results already obtained with the ISE~1 energetic particle analyzer verify the concept and show the power of this technique, but they also point to the need for development of instruments with higher resolution.
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