In space, astronauts are exposed to ionizing radiation that is quantitatively and qualitatively different from terrestrial radiation. This environment includes protons and high-Z high-energy (HZE) ions together with secondary radiation, including neutrons and recoil nuclei that are produced by nuclear reactions in spacecraft materials or tissue. Astronauts who are on missions to the ISS, the Moon or Mars are exposed to ionizing radiation with effective doses in the range of 50 to 2000 mSv (milli-Sievert) projected for possible mission scenarios. Similar doses from terrestrial radiation sources, such as gamma-rays and X-rays, are associated with an increased risk for development of cancer.
Permissible exposure limits (PEL) for Space Radiation limit the allowable mission and career exposure to the space radiation environment based on the projected risk of developing cancer. The PELs are set such that the confidence level of staying within the allowed risk limit is 95%. The use of a median risk estimate could greatly overestimate or underestimate the actual risk to crews because the uncertainties in risk projection models are significant ([95% confidence level/50% confidence level]>4).
Mission, vehicle, and crew selection requirements are outcomes of the Space Radiation PELs, including requirements on vehicle design, mission duration, and age, gender, or past mission history for crew selection.More »
|Organizations Performing Work||Role||Type||Location|
|Johnson Space Center (JSC)||Lead Organization||NASA Center||Houston, Texas|
|Prairie View A & M University||Supporting Organization||Academia||Prairie View, Texas|
|University of Nevada-Las Vegas (UNLV)||Supporting Organization||Academia||Las Vegas, Nevada|
|Wyle Laboratories, Inc.||Supporting Organization||Industry||El Segundo, California|
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