Probability Estimates of Solar Proton Doses During Periods of Low Sunspot Number for Short Duration MissionsIn an earlier paper presented at ICES in 2015, we investigated solar particle event (SPE) radiation exposures (absorbed dose) to small, thinly-shielded spacecraft during a period when the monthly smoothed sunspot number (SSN) was less than 30. Although such months are generally considered "solar-quiet", SPEs observed during these months even include Ground Level Events, the most energetic type of SPE. In this paper, we add to previous study those SPEs that occurred in 1973-2015 when the SSN was greater than 30 but less than 50. Based on the observable energy range of the solar protons, we classify the event as GLEs, sub-GLEs, and sub-sub-GLEs, all of which are potential contributors to the radiation hazard. We use the spectra of these events to construct a probabilistic model of the absorbed dose due to solar protons when SSN < 50 at various confidence levels for various depths of shielding and for various mission durations. We provide plots and tables of solar proton-induced absorbed dose as functions of confidence level, shielding thickness, and mission-duration that will be useful to system designers.
Document ID
20160008938
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Atwell, William (Boeing Research and Technology Houston, TX, United States)
Tylka, Allan J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Dietrich, William F.
Rojdev, Kristina (NASA Johnson Space Center Houston, TX, United States)
Matzkind, Courtney (Boeing Research and Technology Houston, TX, United States)
Date Acquired
July 8, 2016
Publication Date
July 10, 2016
Subject Category
Solar PhysicsSpace Radiation
Report/Patent Number
JSC-CN-35517ICES-2016-453
Meeting Information
Meeting: International Conference on Environmental Systems
Location: Vienna
Country: Austria
Start Date: July 10, 2016
End Date: July 14, 2016
Sponsors: International Conference On Environmental Systems, Inc.