Technical Abstract: On missions to other planets astronauts will be exposed to galactic cosmic rays which are composed of heavy particles (such as 56Fe) and protons. Exposure to these particles can affect the ability of rats to perform a variety of tasks in a manner that parallels the deficits seen in aged animals, indicating that there is the possibility that the performance capabilities of astronauts may be affected similarly to those of aged humans. Previous research has shown that diets containing blueberry or strawberry extract can ameliorate the deficits produced by aging or irradiation using a ground-based analog for exposure to cosmic rays. Rats were placed on diet containing 2% blueberry or strawberry extract for two months prior to exposure to 1.5 Gy of 1 GeV/n 56Fe particles. There were no effects on performance of any group of animals when tested on an ascending fixed-ratio operant task 6 months following exposure. When tested 12 months after exposure the performance of the radiated animals given blueberry extract did not differ from the radiated animals fed the control diet. Both groups performed significantly poorer than the non-irradiated controls. There were no differences between the non-irradiated animals fed control diet and the radiated animals fed the strawberry diet and their performance was significantly better than of the radiated rats fed the blueberry or control diets. The results indicate that diets containing strawberry extract may provide a significant level of radiation protection of exploratory class mission, as well as have some beneficial effects in aging.