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Cosmic Ray Hits in the Central Nervous System at Solar MaximumIt has been suggested that a manned mission to Mars be launched at solar maximum rather than at solar minimum to minimize the radiation exposure to galactic cosmic rays. It is true that the number of hits from highly ionizing particles to critical regions in the brain will be less at solar maximum, and it is of interest to estimate how much less. We present here calculations for several sites within the brain from iron ions (z = 26) and from particles with charge, z, greater than or equal to 15. The same shielding configurations and sites in the brain used in an earlier paper for solar minimum are employed so that direct comparison of results between the two solar activity conditions can be made. A simple pressure-vessel wall and an equipment room onboard a spacecraft are chosen as shielding examples. In the equipment room, typical results for the thalamus are that the probability of any particles with z greater than or equal to 15 and from 2.3 percent to 1.3 percent for iron ions. The extra shielding provided in the equipment room makes little difference in these numbers. We conclude that this decrease in hit frequency (less than a factor of two) does not provide a compelling reason to avoid solar minimum for a manned mission to Mars. This conclusion could be revised, however, if a very small number of hits is found to cause critical malfunction within the brain.
Document ID
20000034097
Acquisition Source
Langley Research Center
Document Type
Reprint (Version printed in journal)
Authors
Curtis, S. B.
(Hutchinson (Fred) Cancer Research Center Seattle, WA United States)
Vazquez, M. E.
(Brookhaven National Lab. Upton, NY United States)
Wilson, J. W.
(NASA Langley Research Center Hampton, VA United States)
Atwell, W.
(Boeing North American, Inc. Houston, TX United States)
Kin, M.-H. Y.
(NASA Langley Research Center Hampton, VA United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 2000
Publication Information
Publication: Advances in Space Research
Publisher: Elsevier Science Ltd.
Volume: 25
Issue: 10
ISSN: 0273-1177
Subject Category
Aerospace Medicine
Distribution Limits
Public
Copyright
Other

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