Life Sciences in the Space Program 



lower orbit or burrowing underground. Spacecraft must be designed with a safe 

 haven (a small, very-well-shielded region where the crew may temporarily seek 

 shelter). 



Mars Colony 



Radiation risks common to those of the previous two missions would be present 

 in establishing a Mars colony. The trip to Mars with its attendant exposures, 

 coupled with the long-term exposure to GCR on the surface of the planet, 

 constitute the radiation exposure. At this point, more consideration must be given 

 to the fact that people may be spending considerable parts of their lives in the 

 colony and that childbearing is likely to occur, given the difficulty of a return trip 

 to Earth. As on the Moon, deep shelters can be built for sleep and SPE 

 protection. But the long-term carcinogenic effect and the cumulative central 

 nervous system damage from HZE particles, mutagenesis, and teratogenesis grow 

 in importance in such a scenario. 



Lifetimes in Space 



Scenarios resulting in people spending lifetimes in space bring together the 

 radiation risks discussed in practically all the prior sections. Depending on the 

 exact nature of the missions, acute effects from SPE's may be the most important, 

 or perhaps the problems associated with procreation in a radiation environment of 

 HZE particles may be dominant. While the possibility of spending a lifetime in 

 space is at the remote edge of current thinking, the previous scenarios naturally 

 lead to this consideration. 



Current Research 



As indicated by the preceding sections, a considerable amount of information is 

 available about the space radiation environment. Progress has been made in 

 determining space radiation fields and in modeling the interaction of radiation 

 with shielding, as well as in the radiobiology of both high and low LET radiation. 



Radiation Source Determination 



The space environment presents four basic categories of radiation, as mentioned 



trapped protons, trapped electrons, SPE's, and GCR. A complete 

 characterization of each type implies knowledge of the spatial distribution, particle 



ice, spectral distributions oi energy, variations in fluence (particles/area/time) 

 and spectrum with time, and (for SPE's and GCR) the relative amounts ot 

 different ion species. 



radiation interacts with the spacecraft and shielding materials. 

 ments are made within satellites or spacecraft, and it is often difficult to 

 r all the varying amounts of shielding surrounding the dosimeters. Once 

 ol the shielding are made, modification ot the radiation field as it passes 

 shielding must he accounted for in determining the free space 



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