can give flare warnings. A systematic study of CMEs and their development and effects near Earth is planned for the Solar Terrestrial Relations Observatory (STEREO) mission; however, its projected launch date of 2004 is later than the current schedule for ISS construction. The Inner Magnetospheric Explorer (IMEX) is scheduled for launch in mid-2001, just after the peak of solar cycle 23. Its mission is to study the dynamics of the inner magnetosphere during major geomagnetic storms. It will be the first mission in the inner magnetosphere to contain a full complement of field and particle detectors (especially electric fields) while there is a full-time upstream monitor in the solar wind (the ACE mission). In addition to these NASA missions there will be NOAA/DOD missions in the GOES/POES series that will include a Solar X-ray Imager (SXI).

4.4 SUMMARY AND RECOMMENDATION

A strategically placed fleet of spacecraft is currently taking data that can provide information on the radiation environment of the ISS orbit in real time and in advance of real time. Spacecraft in geostationary and L1 orbits monitor the Sun and its corona in multiple wavelengths and so can diagnose flare potency and warn of oncoming CMEs with considerable skill (see Section A.4). They also monitor SPE fluxes to give direct information on the radiation intensity within SPE zones. L1 spacecraft monitor solar wind and IMF parameters that can be used to predict the size and shape of SPE zones. Spacecraft in relatively low-altitude polar orbits monitor the flux of relativistic electrons in the outer radiation belt, which the ISS orbit transects. The information will provide flight managers with real-time, high-quality radiation-risk parameters. What is needed is a mechanism to channel the relevant information to the Space Radiation Analysis Group at Johnson Space Center.

Recommendation 4: Promptly convene a meeting of pertinent NASA Space Science Enterprise, SRAG, and SEC managers with the principal investigators of satellite instruments. The meeting would (1) consider ways to extend the capabilities of the current spacecraft fleet to provide real-time radiation data for driving models and specifying the ISS radiation environment and (2) formulate an implementation plan for swiftly channeling such data to radiation risk managers at JSC.

4.5 NOTES AND REFERENCES

1.  

R.C. Canfield, H.S. Hudson, and D.E. McKenzie, ''Sigmoidal morphology and eruptive solar activity," Geophys. Res. Lett., 26, 1999, pp. 627-630.

2.  

See articles in N.U. Crooker, J.A. Joselyn, and J. Feynman, eds., Coronal Mass Ejections, Geophys. Monogr. Ser., 99, American Geophysical Union, Washington, D.C., 1997. See especially H.V. Cane, "The current status in our understanding of energetic particles, coronal mass ejections, and flares," pp. 205-215, and D.V. Reames, "Energetic particles and the structure of coronal mass ejections," pp. 217-226. A more recent reference is D.V. Reams, "Particle acceleration at the sun and in the heliosphere," Space Sci. Rev., in press.

3.  

See the review of shock-acceleration mechanisms by M.A. Lee in Crooker, Joselyn, and Feynman, eds., Coronal Mass Ejections, 1997, pp. 227-234.

4.  

R.A. Leske, R.A. Mewaldt, E.C. Stone, and T.T. 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. 381.

         


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