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Radiation and the International Space Station: Recommendations to Reduce Risk 5 Interagency Connections 5.1 INSTITUTIONAL FACTORS LIMITING INTERAGENCY ABILITY TO PROVIDE BETTER INFORMATION FOR OPERATIONAL RADIATION RISK ASSESSMENTS The radiation monitoring and forecasting support provided to the International Space Station (ISS) is limited in its ability to accurately specify and forecast radiation doses at the location of the ISS. Flight operational safety could be improved and operations made more efficient if environmental observations made at other locations could be extrapolated in time and space to the ISS position using a model. Current (unofficial) flight rules require mission operators to base any concrete protective action on actual measurements of the radiation dose on ISS. The risk to ISS crews of exposure to excess radiation could be significantly reduced if other remote environmental measurements could be accurately applied to the ISS environment to provide advance warning of a developing radiation event. (An analogy to the present situation would be a situation in which no steps may be taken to protect people against a hurricane until a wind monitor on the beach registers a high reading.) The primary obstacle to using remote data is the lack of an accurate modeling capability. As noted throughout this report, models and sensors are available that could significantly improve extrapolation of the radiation dose. However, until they are put in place, information produced from the current space weather system will be unreliable and restricted in usefulness. Two government organizations, NOAA and NASA, are involved in collecting and analyzing remote environmental data and applying the results of the analysis to ISS operations. The NOAA Space Environment Center (SEC) collects observations of the environment made on satellites operated by NOAA, NASA, DOD, and other organizations. The observations are used to develop a wide-ranging specification of the current environment and a forecast of future conditions. The current specification data and the forecast of future changes are supplied to the NASA Space Radiation Analysis Group (SRAG) at Johnson Space Center. SRAG maintains a running record of the astronauts' exposure to radiation and provides the flight surgeon with information on current and predicted changes in the radiation environment. Flight control teams then use this information to make decisions on flight operations. Both SEC and SRAG could raise the quality of their environmental specification, data analysis, and forecast capability if they were in a position to take advantage of the scientific knowledge that is available from research programs in NASA and in the broader scientific community. Improved specification and prediction of the radiation dose to ISS crew members would lead to improved safety and efficiency.
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Radiation and the International Space Station: Recommendations to Reduce Risk A major obstacle stands in the way of implementing any such improvements. Both SRAG and SEC have all they can do just to maintain the data collection and analysis that are needed for ongoing operations. The incorporation of improvements becomes a secondary activity, and the lack of adequate resources and agency support in both organizations is limiting the rate of improvement. Currently, the incorporation of improvements lags far behind taking advantage of new capability. Figure 5.1 illustrates the backlog of models that need to be improved before the ISS radiation environment can be accurately specified and forecast. The transition to better models is virtually stalled by the full commitment of personnel to higher priority operational tasks. Whenever SRAG personnel have the time, they work on integrating improvements. NOAA SEC has introduced a rapid prototyping process in an attempt to overcome the traditionally costly and drawn-out process of "transitioning" models to operational status. This entails subjecting scientific models and results to a linear process of validation and refinement; specifying and designing the user interface; developing mission-qualified software; and "backstepping" the process to make changes necessitated by problems with the science, the validation, or operational or customer requirements. The rapid prototyping process is a dynamic, circular process in which validation, user interfaces, customer products, and software testing are performed simultaneously in the user environment. It involves the scientists who originated the models, the forecasters and other users, and systems support staff working together to reduce the integration time from years to months and to cut costs, which can amount to millions of dollars, by more than 50 percent. The problem with the rapid prototyping process is that even it needs resources beyond the baseline operations staff. SEC has reallocated its limited resources to support the rapid prototyping staff, but the contingencies of day-to-day operations have hampered progress. Figure 5.1 The number of environmental radiation models currently in operation that provide forecasting support to ISS (left column) falls short of the number of models required to provide reliable, accurate forecasts to ISS (right column). The shortfall exists for three types of forecast—forecasting the intensity and time of SPEs (top group), forecasting the area over the polar caps where SPE will reach the ISS (middle group), and forecasting the increase in radiation exposure on board ISS from growth of the trapped radiation belts associated with geomagnetic activity (bottom group).
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Radiation and the International Space Station: Recommendations to Reduce Risk 5.2 RECOMMENDATIONS Recommendation 5a: NASA, NOAA, and the USAF should cooperate to support the activities that would lead to an operational space weather forecasting capability. Recommendation 5b: NOAA should extend the range of its SPE predictions from the present ≥10 MeV to biologically effective energy ranges. Forecasts of particle energies at several steps between 10 and 100 MeV would be a significant improvement for space radiation use as well as for other users who operate satellites and systems in space.
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