William DeCampli, M.D., Ph.D. 

 Chairperson 



Francis D. Moore, M.D. 



Mark H. Phillips, Ph.D. 



Staff Associate 



Radiation 



Long-duration manned space flight and colonization of nearby objects in the solar 

 system will involve the exposure of humans to a number of environmental 

 stresses, one of which is radiation. Such missions will result in the exposure of 

 astronauts to levels and types of radiation not often encountered on Earth. 

 Different mission scenarios involve different radiation hazards, each of which must 

 be evaluated separately. Our accumulated experience concerning radiation in 

 space, as well as knowledge of radiation hazards gathered on Earth, gives us the 

 means to evaluate some of the radiation hazards to be encountered in space and, 

 more importantly, indicates the limits of our knowledge. 



The use of radiation in medicine, and the commercial and military uses of nuclear 

 energy, have led to far-reaching attempts in the United States and other countries 

 to understand radiation and its effects on living creatures. This broad interest 

 means that NASA is not alone in searching for the answers to a number of 

 questions. For many of the relevant measurements and theoretical work, NASA 

 draws on the work of others for its answers. There are, however, a number of 

 problems more or less unique to manned space flight, particularly to missions that 

 extend beyond the Earth's magnetic field for prolonged periods of time. The 

 Earth's magnetic field acts as a shield against the radiation emitted from large solar 

 particle events (SPE's) and from a large fraction of galactic cosmic rays. The 

 radiation from these sources is different in magnitude and biological effect from 

 the radiation sources in the low-Earth orbits (LEO's). 



The Radiation Study Group has worked to determine answers to a series of 

 questions. What are the critical problems regarding the effects of space radiation 

 on humans? What is known about the problems? What needs to be known? How 

 can answers be found? This report will do the following: 1) briefly review what is 

 known about the radiation environments in space and the resulting biological 

 responses, 2) define the principal radiation hazards of different categories of 

 missions, 3) assess current research in these areas, and 4) make recommendations 

 for the resolution of outstanding problems in the precise determination of 

 radiation environments and their effects on human health. 



The information for this report was obtained from published papers and in 

 response to a solicitation by the Study Group of the views and recommendations 



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