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Propensity and Risk Assessment for Solar Particle Events: Consideration of Integral Fluence at High Proton EnergiesFor future space missions with longer duration, exposure to large solar particle events (SPEs) with high energy levels is the major concern during extra-vehicular activities (EVAs) on the lunar and Mars surface. The expected SPE propensity for large proton fluence was estimated from a non-homogeneous Poisson model using the historical database for measurements of protons with energy > 30 MeV, Phi(sub 30). The database includes a continuous data set for the past 5 solar cycles. The resultant SPE risk analysis for a specific mission period was made including the 95% confidence level. In addition to total particle intensity of SPE, the detailed energy spectra of protons especially at high energy levels were recognized as extremely important parameter for the risk assessment, since there remains a significant cancer risks from those energetic particles for large events. Using all the recorded proton fluence of SPEs for energies >60 and >100 MeV, Phi(sub 60) and Phi(sub 100), respectively, the expected propensities of SPEs abundant with high energy protons were estimated from the same non-homogeneous Poisson model and the representative cancer risk was analyzed. The dependencies of risk with different energy spectra, for e.g. between soft and hard SPEs, were evaluated. Finally, we describe approaches to improve radiation protection of astronauts and optimize mission planning for future space missions.
Document ID
20080013376
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Kim, Myung-Hee
(Universities Space Research Association Houston, TX, United States)
Hayat, Matthew J.
(Universities Space Research Association Houston, TX, United States)
Feiveson, alan H.
(NASA Johnson Space Center Houston, TX, United States)
Cucinotta, Francis A.
(NASA Johnson Space Center Houston, TX, United States)
Date Acquired
August 24, 2013
Publication Date
January 1, 2008
Subject Category
Man/System Technology And Life Support
Meeting Information
Meeting: 37th COSPAR Scientific Assembly
Location: Montreal
Country: Canada
Start Date: July 13, 2008
End Date: July 20, 2008
Distribution Limits
Public
Copyright
Other

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