Managing Space Radiation Risk in the New Era of Space Exploration (2008) / Chapter Skim
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1 Introduction
1 Introduction
Pages 7-18
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From page 7... ...
In terms of radiation, the mission could be compromised by these short-term consequences or "acute effects," which may include headaches, dizziness, nausea, fatigue, and illness ranging from mild to fatal. In addition, mission objectives could be missed because measures to avoid excess radiation exposure might restrict crew activity.
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ORGANIZATION OF THIS REPORT The first chapter of this report outlines some background information on the Vision for Space Exploration, NASA's work in radiation protection, and permissible radiation exposure limits. Chapter 2 reviews the current knowledge of the radiation environments likely to be experienced by astronauts, as well as the knowledge gaps.
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NASA determines its research portfolio in consultation with the science research community, including the National Council on Radiation Protection and Measurements (NCRP) and the Space Studies Board and other organizations within the National Research Council.
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Operational and engineering organizations within NASA also collaborate closely with the solar science and space weather community on matters of space radiation warning, monitoring, and environmental measurements. OVERVIEW OF RADIATION PROTECTION NASA develops human system standards to ensure an appropriate environment for human habitation, qualified human participants, a necessary level of medical care, and risk mitigation strategies against the deleterious effects of spaceflight.
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Figure 1-2 shows astronaut exposure rate by mission year and illustrates the variability of average daily dose rate experience through 2005. This previous human spaceflight experience Other examples: 100 Chest x-ray .005 to .02 cSv Annual limit for astronauts Cross-country round trip .005 cSv in low Earth orbit High-altitude dose rate .002 cSv/hour Effective Dose, cSv/year Effective Dose, cSv in a year Dose rates on orbit .01 to .1 cSv/day 10 Recommended limit for "radiation workers" Astronaut mission dose, measured 1 Recommended annual limit for U.S.
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From page 12... ...
Apollo missions were only a few days long, and so the radiation protection involved minimizing travel through the Van Allen radiation belts that encircle Earth in order to avoid solar particle events. There have been longer missions on the space shuttle and the International Space Station, but these took place within the protections of Earth's magnetosphere.
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Extravehicular activities (EVAs) may be scheduled for periods of reduced solar activity and no transit through radiation belts; radiation measurements are used to verify radiation exposure and provide warning for retreat to storm shelters.
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: a safety principle, as well as a regulatory requirement, that emphasizes keeping doses of and exposure to radiation as low as possible using reasonable methods, and not treating dose limits as "tolerance values"; defined at NASA as limiting radiation exposure to a level that will result in an estimated risk below the limit of the 95 percent confidence level. biological end point: effect or response being assessed, e.g., cancer, cataracts.
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risk of exposure induced death (REID) : measure of risk used by NASA as a standard for radiation protection; reflects a calculation of the probability of death due to exposure to radiation in space.
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Space Radiation Research Recommendations of 2006 Because of the unique nature of the space radiation environment beyond LEO, for which no epidemiological data on cancer incidence or mortality exist, guidance on radiation exposures to limit excess cancer mortality to some desired level, such as 3 percent, could not be provided. At the request of NASA, the NCRP published NCRP Report No.
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2.5 [0.76, 8.3] Mars surface mission, 400 days in deep space, 600 days on surface Male 3.4 [1.1, 10.8]
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2006. Information Needed to Make Radiation Protection Recommendations for Space Missions Beyond Low-Earth Orbit.
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