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Managing Lunar and Mars Mission Radiation RisksThis document addresses calculations of probability distribution functions (PDFs) representing uncertainties in projecting fatal cancer risk from galactic cosmic rays (GCR) and solar particle events (SPEs). PDFs are used to test the effectiveness of potential radiation shielding approaches. Monte-Carlo techniques are used to propagate uncertainties in risk coefficients determined from epidemiology data, dose and dose-rate reduction factors, quality factors, and physics models of radiation environments. Competing mortality risks and functional correlations in radiation quality factor uncertainties are treated in the calculations. The cancer risk uncertainty is about four-fold for lunar and Mars mission risk projections. For short-stay lunar missins (<180 d), SPEs present the most significant risk, but one effectively mitigated by shielding. For long-duration (>180 d) lunar or Mars missions, GCR risks may exceed radiation risk limits. While shielding materials are marginally effective in reducing GCR cancer risks because of the penetrating nature of GCR and secondary radiation produced in tissue by relativisitc particles, polyethylene or carbon composite shielding cannot be shown to significantly reduce risk compared to aluminum shielding. Therefore, improving our knowledge of space radiobiology to narrow uncertainties that lead to wide PDFs is the best approach to ensure radiation protection goals are met for space exploration.
Document ID
20050196720
Document Type
Technical Publication (TP)
Authors
Cucinotta, Francis A. (NASA Johnson Space Center Houston, TX, United States)
Kim, Myung-Hee Y. (Wyle Labs., Inc. Houston, TX, United States)
Ren, Lei (Universities Space Research Association Houston, TX, United States)
Date Acquired
September 7, 2013
Publication Date
July 1, 2005
Subject Category
Aerospace Medicine
Report/Patent Number
S-960/PT1
NASA/TP-2005-213164/PT1
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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