PRINCIPAL INVESTIGATOR (S ): John E. Hewitt 



EXPERIMENT TITLE/NUMBER : Radiation Exposures During the Biosatellite II 



Flight 



PROGRAM/MISSION : Biosatellite II 



CLASSIFICATION : Animal, Plant, Microorganism 



DISCIPLINE(S) : Radiobiology 



OBJECTIVES : To determine the combined effects of radiation and weightlessness 

 on lethality and mutagenesis in a variety of living systems. 



PROTOCOL : The biologic material from each experiment was divided into four 

 groups; flight groups irradiatedgand non-irradiated, and Earth control groups 

 irradiated and non-irradiated. Sr was used as the radiation source and 

 Lithium fluoride (LiF) thermoluminescent powder was selected as the primary 

 dosimeter. The packages were placed in the capsule at different distances 

 from the source so that each would receive its correct exposure. 



EQUIPMENT : Capsule, experiment packages, nuclear emulsion package, 

 backscatter shield, heat shield, source holder Sr source, LiF powder 

 dosimeters, CaF 2 dosimeters. 



RESULTS : The radiation exposures in the control areas were quite low. Few 



were above 0.5 R. From nuclear emulsion measurements, an upper limit dose due 



to protons was 40 mB for the mission. There were 10.1 traversals of atomic 

 nuclei of Z 2 20/cm during the mission. 



CONCLUSIONS : Nuclear emulsions measurements verified that radiation doses due 

 to space radiations are very low in orbits similar to that of Biosatellite II. 

 It is highly unlikely that any difference found between the biologic responses 

 of the same experiment in the flight and Earth control capsules could be 

 attributed to radiation exposure differences, nor could any unusual results be 

 attributed to the presence in the capsules of a large component of low-energy 

 radiation produced by multiple scattering. 



PUBLICATIONS: 268 



163 



