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Space Radiation Hazards and the Vision for Space Exploration: Report of a Workshop
that location. Regarding SEP events, more work is needed to understand the most appropriate models and methods that characterize these conditions, including extreme-event studies, risk-based models, and databased analysis of long-term records.
Improved models of proton and heavy-ion environments (flux, fluence, and energy spectra) in SEP events are needed because of their effects on systems. Between Earth and Mars, the data on helio-radial dependence of the flux and fluence of SEP events are needed. To better design, protect, and test electronics, new models are needed to better incorporate SEP event conditions and galactic cosmic ray models, including correct solar-cycle modulation of composition. These models need improvements that better address geometry complexity, decreasing feature size, track effects, and single-event transient effects. New physics-based modeling, incorporating particle interactions and device physics, offers improved guidance for design, selection, and protection of devices and instruments.
Real-time knowledge of space weather conditions during flights to the Moon and Mars is important for mission success, but it requires improved observations, modeling, and understanding. Without a doubt, new tools will be needed for forecasting space environmental conditions on Mars missions. Solar particle event occurrence and the expected time profile at the vehicle location are among the most serious environmental conditions to contend with, yet they are also among the most difficult to forecast. For the moment, since nowcasts are expected to be more reliable than forecasts, the ability to provide nowcasts was given greater importance by the group than forecasting. It was recognized that missions not only depend on warnings, forecasts, and nowcasts of space weather events, but they need “all-clears” so that they know when they can resume normal operations. In some situations, the time it takes for signals of solar events to propagate from the Sun to Earth and then to the vehicle, including the time for processing signals at Earth, will take far more time than is desirable for the protection of instruments and astronauts on the vehicle. Therefore, crews will want to have autonomous crew situational awareness for vehicle operations. It has been pointed out by Kunches et al. (1991) that astronauts are a “proactive group” with a “spirit of adventure and a desire to chart their own destiny.” It would therefore be advantageous to provide the crew with tools to monitor space weather from their vantage point, not only to give them the ability to rapidly respond, but for their own psychological well-being and to maintain a long-term record of actual mission radiation conditions.
Generally, the engineering approach is to harden systems against worst cases; however, the unexpected can always occur. In such circumstances, a number of actions can be taken in response to predictions of poor space weather. Sensors can be safed, noncritical systems can be shut down to prevent damage and latch-up, sensors can be oriented in a direction that is least susceptible to damage, increased attention can be given to monitoring operations and to the interpretation of sensor data, and mission activities can be limited during high-background events.
Barbieri, L.P., and R.E. Mahmot. 2004. October–November 2003’s space weather and operations lessons learned. Space Weather 2: S09002, doi:10.1029/2004SW000064.
Kunches, J.M., G.R. Heckman, E. Hildner, and S.T. Seuss. 1991. Solar Radiation Forecasting and Research to Support the SpaceExploration Initiative. Space Environment Laboratory (SEL) Special Report. National Oceanic and Atmospheric Administration SEL, Boulder, Colo. February.