Radiation and the International Space Station Recommendations to Reduce Risk (2000) / Chapter Skim
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4 Spacecraft Sources of Operational Radiation Data
4 Spacecraft Sources of Operational Radiation Data
Pages 39-44
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From page 39... ...
Moreover, they continuously monitor the full, unshielded intensity of the solar energetic particles, which specifies the radiation intensity within the SPE zones. As an example of the radiation profiles that are relevant, Figure 4.1 shows a series of severe SPEs that included the most intense event of solar cycle 22 (that event produced some of the points in the danger area delineated in Figure 2.3~.
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From page 40... ...
, a shock wave forms ahead of it that energizes particles as it moves through the interplanetary medium. According to one model of shock acceleration, a shock can produce both a long SPE profile, lasting 1 or 2 days, and a shock spike such as that seen in the first SPE in Figure 4.1.3 The severity of a shock-generated SPE depends on the speed of the parent CME and on its launch site on the Sun; the most intense cases are associated with events that occur near the center of the visible disk, as was the case for the event shown in Figure 4.1.
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From page 41... ...
The gray area in the polar regions marks the geographic location of energetic ions observed on SAMPEX during a large SPE (in November 1992~. The gray area is offset from the ISS orbit because Earth's magnetic field is offset from the spin axis, and it can be seen that this causes some ISS orbits to pass into the gray zone of particle access, while other orbits miss it entirely.
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From page 42... ...
The High Energy Solar Spectroscopic Imager (HESSI) will be launched in mid-2000 to explore the basic physics of particle acceleration and energy release in solar flares by carrying out simultaneous, high-resolution imaging and spectroscopy of solar flares, from 3 keV X rays to 20 MeV gamma rays, with high time resolution.
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From page 43... ...
The particle cutoff latitude measured on SAMPEX moved from ~66 degrees to ~60 degrees many hours before the arrival of the shock and even before Earth' s magnetic field (heavy black line) registered a change.
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From page 44... ...
von Rosenvinge, "Geomagnetic Cutoff Variations During Solar Energetic Particle Events Implications for the Space Station," Proceedings of the 25th International Cosmic Ray Conference, 2, Space Research Unit, Department of Physics, Potchefstroom University for Christian Higher Education, South Africa, 1997, p.
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