Solar Proton Event Planning for Lunar and Mars Human Missions

During the past 50 years a number of extremely large solar proton events (SPEs) have occurred. It was fortuitous that the major August 1972 SPE occurred between two Apollo missions: Apollo 16 (April 1972) and Apollo 17 (December 1972). The National Oceanic and Atmospheric Administration (NOAA) provides solar “nowcasts” and forecasts and real-time solar data for mission support to NASA Johnson Space Center Mission Control personnel. This support dates back to the late Apollo program. Some of these major SPEs, which can produce an acute radiation exposure if the crew is not properly shielded, have impacted human space operations where the crews have been instructed to move to more heavily shielded locations within the vehicle to minimize their radiation exposures. In this paper, a review of the major SPEs that have occurred will be presented along with corresponding depth-dose calculations. Mission scenarios are presented for operations in free space and on the lunar and Mars surfaces. Contingency plans are discussed in detail and outlines the proposed NOAA support.